Physics Book - User contributions [en]

Spark Plugs

2017-11-28T23:24:19Z

Gellis9:

Claimed By Christopher Skretkowicz
Claimed By Edward Mauger Spring 2017
'''Claimed By Geraghty Anne Ellis Fall 2017 (Edits)'''

This page chronicles the inner workings and hidden mechanisms involved with spark plug applications, and their integration with automotive ignition systems in the real world.

==Basic Engine Theory==

In order to understand how spark plugs work, there must be some background explanation for the systems that use them. Internal combustion engines are those that rely on the ignition of the air-fuel mixture to create the energy used to power most modern vehicles. [The different types [https://en.wikipedia.org/wiki/Two-stroke_engine two-stroke] and four-stroke. [https://auto.howstuffworks.com/rotary-engine4.htm Rotary engines] use the four-stroke cycle but accomplish combustion much differently. Spark plugs are used in all aforementioned applications for the same purpose. For simplicity, the four-stroke IC engine will be discussed in slightly more detail.

There are four main phases or "strokes" for each combustion chamber of the four-stroke engine: intake, compression, power, and exhaust. Regardless of how many cylinders, all of these engines have a firing order - order of which spark plugs are ignited. This sequential order, rather than all firing at once, allows for the continuous motion of the crankshaft.

[[File:IC_engine.jpg]]

[[File:4-Stroke-Engine-with-airflows.gif]] [[File:enginefiringorder.gif]]

===Intake===

Air is pulled into the engine from the environment by the air intake and stored in the plenum. From the plenum, air enters the intake manifold where fuel injectors will distribute the proper ratio of fuel to the amount of air. Naturally aspirated engines (no turbos, superchargers or anything used to force more air into the engine) typically run at a 14:1 air/fuel ratio. The intake manifold is bolted directly onto the engine so that this mixture can enter the combustion chamber or bore. Intake valves during seal the opening to the chamber on the intake side of the engine; during this phase or "stroke" however, they are opened to allow the air-fuel mixture into the bore. [https://en.wikipedia.org/wiki/Piston Pisons], which travel up and down the bore and connected to the crankshaft (see below), are towards the bottom of the bore during this stroke to allow for the most air to enter the combustion chamber and will reach [https://en.wikipedia.org/wiki/Dead_centre_(engineering)#Reciprocating_engine BDC or bottom dead center].

[[File:Ferrari_air_intake_system.jpg|400px]]

[https://en.wikipedia.org/wiki/Camshaft Camshafts] are used to control when these valves(both intake and exhaust, which will be discussed later) open and close and are directly connected to the [https://en.wikipedia.org/wiki/Crankshaft crankshaft], which in short translate the reciprocating motion of the engine to rotational motion which will eventually be translated through the drivetrain to [https://itstillruns.com/car-move-5104221.html propell the vehicle forward.]

===Compression===

In this stroke, the piston moves to the top of the bore, compressing the air-fuel mixture. Both intake and exhaust valves are shut to not allow for any air to escape. Compressing the mixture enables more energy to be expelled when it is ignited and generates heat, which enables the combustion process to happen more quickly after the mixture is ignited. This process follows the ideal gas law in that as pressure is increased and volume decreased, so must the temperature increase.

===Power===

During the power stroke, just before the piston reaches TDC, or top dead center (the very top of the bore), the spark plug ignites creating a combustion reaction. This explosion forces the piston downwards, and so the crankshaft continues to rotate.

===Exhaust===

With the piston moving back up the bore, what remains of the air-fuel mixture after combustion is no longer needed. The camshaft allows the exhaust valve to open and these exhaust gases are pushed out of the combustion chamber through the exhaust manifold, into the [https://en.wikipedia.org/wiki/Catalytic_converter catalytic converter] to lessen the amount of pollution produced, through the [https://en.wikipedia.org/wiki/Muffler muffler] to lessen the noise emitted, and out the tailpipe into the environment.
Back inside the engine, the exhaust valve closes and the intake stroke begins again.

[[File:Exhaust_system.jpg]]

==The Main Idea==

Spark plugs are essentially what their namesake says they are: plugs that screw into the cylinders of an engine and produce sparks that ignite fuel in combustion engines during the power stroke. Spark plugs take advantage of Faraday's Law and induction to create large spikes of voltage, typically around 40,000 V, across an electrode gap that would otherwise be impossible to achieve with a regular 12 volt car battery. Their two main functions are to produce spark and to remove heat from the combustion chamber.

[[File:Spark_plug.gif]]

===Mechanical Ignition===

Automotive ignition systems are either mechanically or electrically timed and powered by a 12V battery. A mechanically timed ignition system contains a distributor, coil pack, spark plugs, and wires.

[[File:220px-Car_ignition_system.svg.png]]

Each coil in the coil pack consists of a primary winding and a secondary winding, which share a common magnetic core. Both coils are connected to the battery. Additionally, the primary is connected to the distributor and the secondary coil is connected to the spark plugs through the cap and rotor within the distributor. The secondary winding has more turns in its coil, resulting in a much higher voltage that runs through it.

[[File:CarDistributor.jpg|250px]] [[File:Ls2_coil_schematic.jpg|250px]]

Initially, the [https://en.wikipedia.org/wiki/Contact_breaker contact breaker] is closed, completing the circuit and allowing current to flow from the battery, through the primary coil and contact breaker and back through the battery. This flow of current creates a [http://www.physicsbook.gatech.edu/Magnetic_field magnetic field] in the primary's core. The distributor shaft is attached to the camshaft lobes, which dictate when the contact breaker is open or closed. If open, without the current flow, there is no magnetic field. Because this connection is dependent on the cams, there is a cyclical repetition of the existence of a magnetic field. The rapid change of this field causes a large change in [http://www.physicsbook.gatech.edu/Magnetic_Flux magnetic flux]. According to [http://www.physicsbook.gatech.edu/Faraday%27s_Law Faraday's Law], this change in magnetic flux will cause a curly electric field which will induce a large voltage that will be crucial to spark plug function.

[[File:magneticfieldIgsyst.jpg|400px]]

Because the primary coil is wrapped around the secondary coil, a varying magnetic field induces an electric current to be run through the secondary coil, which in turn produces a much larger EMF due to the number of loops in the coil. This will take the inputted DC voltage (again, typically 12-24V) and output 15,000V-40,000V AC. That current is fed to the spark plugs, which have a center electrode that is isolated from grounding electrode, grounded through the spark plug casing to the engine, which shares a ground with the coil. The two electrodes have a gap between them that is set typically between .4mm and 1.7mm. A smaller gap requires less voltage from the coil, a larger gap requires more voltage from the coil. In this case, the spark plug's electrodes act as a capacitor with the air in the cylinder being a dielectric insulator. For a spark to occur, the voltage from the coil must be sufficient to cause dielectric breakdown of the air. As the current crosses the electrodes, there is a drastic raise in the temperature upwards of 60,000K, creating a small spark. When this happens, a click from the spark plug can be heard. This spark ignites the air-fuel mixture in the cylinder continuing the crankshaft motion. The distributor cap and rotor determine which cylinder receives a spark to match the firing order.

===Electronic Ignition===

An electronic ignition system, common among modern cars, solves some of the flaws of the mechanical system: wear, oxidation, and contact of breaker points. Angular sensors replace these breaker points and tell the [https://en.wikipedia.org/wiki/Engine_control_unit engine control unit(ECU)].

[[File:ElectronicIgnitionSystem.jpg]]

A common example, Hall effect sensors, relies on magnetic fields to send signals to the ECU. (See [http://www.physicsbook.gatech.edu/Hall_Effect Hall Effect] for more in-depth information on the fundamental principles behind this). Once the magnetic flux density around the sensor exceeds a certain threshold, it generates voltage, triggering a device to send a large amount of current through the coils in the coil pack. This magnetic flux is created by a rotating magnet on the distributor shaft. The impact to the spark plugs themselves is the same.

[[File:Halleffectsensor.gif]] [[File:Mag26.gif]]

===A Mathematical Model===

The primary physics equation used when analyzing spark plugs is Faraday's Law, which states <math>\mathcal{E} = -{{d\Phi_B} \over dt} \ </math>, where <math>\mathcal{E}</math> is the electromotive force(EMF) produced from the time-varying magnetic flux Φ''B''. The flux is given by <math> \int_{\Sigma} \mathbf{B} \cdot d\mathbf{A}. </math>

[[File:Faraday+s+Law+and+Ignition.jpg|500px]]

The basic equation for dielectric breakdown is given as <math>{{V_d}_b}= {{E_d}_sd}</math>

V''db'' represents the dielectric breakdown voltage and E''ds'' represents the dielectric strength of the insulator and d is the distance. The dielectric strength of air is 3x10^6 V/m, so at a gap of 1mm, the required voltage for dielectric breakdown is 30,000V.

That is a good model for the spark outside of an engine at ambient temperature but there are other variables to consider for voltage required inside of the engine because the dielectric strength will change. If it is assumed the spark plugs have no sort of buildup from carbon or oil, the other variables that effect dielectric breakdown voltage are electrical frequency, temperature, the fact that the dielectric material is not just air but a mixture of gasoline and air at a specific ratio, plus the shape, size, and thickness of the electrodes of the spark plug. The temperature inside of the combustion chamber is typically around 1500 degrees Celcius, increased temperature decreases the dielectric strength. Increased electrical frequency decreases the dielectric strength which is why some manufacturers have researched using higher frequency ignition systems. Gasoline's chemical makeup can vary but Benzene, a component of gasoline, has a dielectric strength of 163x10^6 V/m which is much higher than the dielectric strength of air.

===Further Explanation of System===

[https://www.youtube.com/watch?v=__FRCSvEYdE Ignition System Function]
[https://www.youtube.com/watch?v=sFiGsCkAMbk Description of Spark Plug]

==Examples==

http://vicsauto.net/images/anatomy_sparkplug.JPG

Anatomy of a Typical Spark Plug

https://media.boingboing.net/wp-content/uploads/2015/06/skd282544sdc_XS.jpg

Firing Spark Plug

Ex. A spark plug in a car has electrodes separated by a gap of 0.025in. To create a spark and ignite the air-fuel mixture in the engine, an electric field of 3.0x10^6 V/m is required in the gap.
a) What potential difference must be applied to the spark plug to initiate a spark?
b) If the separation between electrodes is increased, does the required potential difference increase, decrease, or stay the same? Explain.
c) Find the potential difference for a separation of 0.050 in.

[[File:Spark_plug_problem-page-001.jpg|400px]]

[[File:Spark_plug_problem-page-002.jpg|200px]]

==Connectedness==
Spark Plugs allow gasoline engines to run. The heat from the spark generated by the ignition system causes the gasoline to combust and drive the piston away to turn the crankshaft. This only works if the spark's heat is above the flashpoint of the fuel. Gasoline has a relatively low flashpoint while diesel has a relatively high flashpoint which is why gasoline engines operate at lower pressures with and with spark plugs (spark ignition) and diesels operate at much higher pressures with no spark (compression ignition). Those concepts would apply more so in a course covering thermodynamics. I am a DIY mechanic who works on both gasoline and diesel engines so understanding the physics behind the ignition system of an engine is useful for my tinkering and modifications of the vehicles I work on. A spark ignition system is mostly related to electrical engineering but as it's fundamental concepts are fairly basic in terms of electrical engineering, they are covered in the mechanical engineering curriculum. The stresses, forces and heat generated by combustion are certainly integral concepts of the mechanical engineering curriculum.

Editor 2: I also do extensive mechanic and repair work on both gasoline and diesel engines. I've interned for Cummins Engines and want to pursue a career developing performance engines for racing applications, so understanding the physics behind spark plugs and ignition systems and how this integrates within engine performance is extremely important. As a Powertrain member for GT Motorsports, understanding these concepts is critical to component design and development for competition success.

==History==
Spark plugs have been around since at least 1859. There are reports that a rudimentary version of the spark plug was originally invented by an African-American man by the name of Edmond Berger in 1839 but he did not patent it. Spark ignition was first used in an early internal combustion engine created by Belgian inventor Étienne Lenoir in 1859. British physicist Sir Oliver Lodge provided many improvements to the design in the 1880s. At the turn of the century, many patents for spark plugs were filed by Nikola Tesla, Robert Bosch, Frederick Richard Simms but Bosch is usually credited with the first commercially viable high-voltage spark plugs (1802) and Albert Champion is credited with expanding its use when he built a spark plug factory in Boston in 1805 and supplied American automobile manufacturers. Sir Oliver Lodge's children started Lodge Plug Company in Britain which allowed the British automobile industry to take off. Similarly, Bosch's spark plugs were largely used by automobile manufacturers in mainland Europe.

Throughout the years, improvements have been made such as adding resistors to the plugs to decrease radio interference, different electrode materials, and the ignition system itself has moved from points and distributors to electronic controllers. Spark plugs have been used in things other than internal combustion engines, such as the second and third stages of the Saturn V rocket.

== See also ==

[http://www.physicsbook.gatech.edu/Magnetic_Field_of_a_Solenoid Magnetic Field of a Solenoid]

[http://www.physicsbook.gatech.edu/Curly_Electric_Fields Curly Electric Fields]

[http://www.physicsbook.gatech.edu/Faraday%27s_Law Faraday's Law]

[http://www.physicsbook.gatech.edu/Inductance Inductance]

[http://www.physicsbook.gatech.edu/Transformers_from_a_physics_standpoint Transformers]

===External links===

[http://www.ngk.com.au/spark-plugs/technical-information/spark-plug-anatomy-construction Spark Plug Anatomy]

==References==

http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/ignition.html

http://auto.howstuffworks.com/spark-plugs.htm

https://www.youtube.com/watch?v=b2udCm7DMzU

http://physics.info/dielectrics/

http://www.engineeringtoolbox.com/liquid-dielectric-constants-d_1263.html

http://www.themotormuseuminminiature.co.uk/inv-jeanjoseph-etienne-lenoir.php

https://www.hemmings.com/magazine/hcc/2006/01/Albert-Champion/1281809.html

http://www.kisouman.com/spark_plug_description-1071.html

http://mechanicstips.blogspot.com/2015/06/how-four-stroke-cycle-engine-works.html

http://www.gsparkplug.com/shop/how-spark-plugs-work/

http://www.mech4study.com/2017/03/magneto-ignition-system-parts-function-working-advantages-and-disadvantages.html

https://www.slideshare.net/jesscar/piston-engines-ignition

http://www.electronics-tutorials.ws/electromagnetism/hall-effect.html

[[Category:Real Life Applications of Electromagnetic Principles]]

Spark Plugs

2017-11-28T23:23:46Z

Gellis9:

Claimed By Christopher Skretkowicz
Claimed By Edward Mauger Spring 2017
'''Claimed By Geraghty Anne Ellis Fall 2017 (Edits)'''

This page chronicles the inner workings and hidden mechanisms involved with spark plug applications, and their integration with automotive ignition systems in the real world.

==Basic Engine Theory==

In order to understand how spark plugs work, there must be some background explanation for the systems that use them. Internal combustion engines are those that rely on the ignition of the air-fuel mixture to create the energy used to power most modern vehicles. [The different types [https://en.wikipedia.org/wiki/Two-stroke_engine two-stroke] and four-stroke. [https://auto.howstuffworks.com/rotary-engine4.htm Rotary engines] use the four-stroke cycle but accomplish combustion much differently. Spark plugs are used in all aforementioned applications for the same purpose. For simplicity, the four-stroke IC engine will be discussed in slightly more detail.

There are four main phases or "strokes" for each combustion chamber of the four-stroke engine: intake, compression, power, and exhaust. Regardless of how many cylinders, all of these engines have a firing order - order of which spark plugs are ignited. This sequential order, rather than all firing at once, allows for the continuous motion of the crankshaft.

[[File:IC_engine.jpg]]

[[File:4-Stroke-Engine-with-airflows.gif]] [[File:enginefiringorder.gif]]

===Intake===

Air is pulled into the engine from the environment by the air intake and stored in the plenum. From the plenum, air enters the intake manifold where fuel injectors will distribute the proper ratio of fuel to the amount of air. Naturally aspirated engines (no turbos, superchargers or anything used to force more air into the engine) typically run at a 14:1 air/fuel ratio. The intake manifold is bolted directly onto the engine so that this mixture can enter the combustion chamber or bore. Intake valves during seal the opening to the chamber on the intake side of the engine; during this phase or "stroke" however, they are opened to allow the air-fuel mixture into the bore. [https://en.wikipedia.org/wiki/Piston Pisons], which travel up and down the bore and connected to the crankshaft (see below), are towards the bottom of the bore during this stroke to allow for the most air to enter the combustion chamber and will reach [https://en.wikipedia.org/wiki/Dead_centre_(engineering)#Reciprocating_engine BDC or bottom dead center].

[[File:Ferrari_air_intake_system.jpg|400px]]

[https://en.wikipedia.org/wiki/Camshaft Camshafts] are used to control when these valves(both intake and exhaust, which will be discussed later) open and close and are directly connected to the [https://en.wikipedia.org/wiki/Crankshaft crankshaft], which in short translate the reciprocating motion of the engine to rotational motion which will eventually be translated through the drivetrain to [https://itstillruns.com/car-move-5104221.html propell the vehicle forward.]

===Compression===

In this stroke, the piston moves to the top of the bore, compressing the air-fuel mixture. Both intake and exhaust valves are shut to not allow for any air to escape. Compressing the mixture enables more energy to be expelled when it is ignited and generates heat, which enables the combustion process to happen more quickly after the mixture is ignited. This process follows the ideal gas law in that as pressure is increased and volume decreased, so must the temperature increase.

===Power===

During the power stroke, just before the piston reaches TDC, or top dead center (the very top of the bore), the spark plug ignites creating a combustion reaction. This explosion forces the piston downwards, and so the crankshaft continues to rotate.

===Exhaust===

With the piston moving back up the bore, what remains of the air-fuel mixture after combustion is no longer needed. The camshaft allows the exhaust valve to open and these exhaust gases are pushed out of the combustion chamber through the exhaust manifold, into the [https://en.wikipedia.org/wiki/Catalytic_converter catalytic converter] to lessen the amount of pollution produced, through the [https://en.wikipedia.org/wiki/Muffler muffler] to lessen the noise emitted, and out the tailpipe into the environment.
Back inside the engine, the exhaust valve closes and the intake stroke begins again.

[[File:Exhaust_system.jpg]]

==The Main Idea==

Spark plugs are essentially what their namesake says they are: plugs that screw into the cylinders of an engine and produce sparks that ignite fuel in combustion engines during the power stroke. Spark plugs take advantage of Faraday's Law and induction to create large spikes of voltage, typically around 40,000 V, across an electrode gap that would otherwise be impossible to achieve with a regular 12 volt car battery. Their two main functions are to produce spark and to remove heat from the combustion chamber.

[[File:Spark_plug.gif]]

===Mechanical Ignition===

Automotive ignition systems are either mechanically or electrically timed and powered by a 12V battery. A mechanically timed ignition system contains a distributor, coil pack, spark plugs, and wires.

[[File:220px-Car_ignition_system.svg.png]]

Each coil in the coil pack consists of a primary winding and a secondary winding, which share a common magnetic core. Both coils are connected to the battery. Additionally, the primary is connected to the distributor and the secondary coil is connected to the spark plugs through the cap and rotor within the distributor. The secondary winding has more turns in its coil, resulting in a much higher voltage that runs through it.

[[File:CarDistributor.jpg|250px]] [[File:Ls2_coil_schematic.jpg|250px]]

Initially, the [https://en.wikipedia.org/wiki/Contact_breaker contact breaker] is closed, completing the circuit and allowing current to flow from the battery, through the primary coil and contact breaker and back through the battery. This flow of current creates a [http://www.physicsbook.gatech.edu/Magnetic_field magnetic field] in the primary's core. The distributor shaft is attached to the camshaft lobes, which dictate when the contact breaker is open or closed. If open, without the current flow, there is no magnetic field. Because this connection is dependent on the cams, there is a cyclical repetition of the existence of a magnetic field. The rapid change of this field causes a large change in [http://www.physicsbook.gatech.edu/Magnetic_Flux magnetic flux]. According to [http://www.physicsbook.gatech.edu/Faraday%27s_Law Faraday's Law], this change in magnetic flux will cause a curly electric field which will induce a large voltage that will be crucial to spark plug function.

[[File:magneticfieldIgsyst.jpg|400px]]

Because the primary coil is wrapped around the secondary coil, a varying magnetic field induces an electric current to be run through the secondary coil, which in turn produces a much larger EMF due to the number of loops in the coil. This will take the inputted DC voltage (again, typically 12-24V) and output 15,000V-40,000V AC. That current is fed to the spark plugs, which have a center electrode that is isolated from grounding electrode, grounded through the spark plug casing to the engine, which shares a ground with the coil. The two electrodes have a gap between them that is set typically between .4mm and 1.7mm. A smaller gap requires less voltage from the coil, a larger gap requires more voltage from the coil. In this case, the spark plug's electrodes act as a capacitor with the air in the cylinder being a dielectric insulator. For a spark to occur, the voltage from the coil must be sufficient to cause dielectric breakdown of the air. As the current crosses the electrodes, there is a drastic raise in the temperature upwards of 60,000K, creating a small spark. When this happens, a click from the spark plug can be heard. This spark ignites the air-fuel mixture in the cylinder continuing the crankshaft motion. The distributor cap and rotor determine which cylinder receives a spark to match the firing order.

===Electronic Ignition===

An electronic ignition system, common among modern cars, solves some of the flaws of the mechanical system: wear, oxidation, and contact of breaker points. Angular sensors replace these breaker points and tell the [https://en.wikipedia.org/wiki/Engine_control_unit engine control unit(ECU)].

[[File:ElectronicIgnitionSystem.jpg]]

A common example, Hall effect sensors, relies on magnetic fields to send signals to the ECU. (See [http://www.physicsbook.gatech.edu/Hall_Effect Hall Effect] for more in-depth information on the fundamental principles behind this). Once the magnetic flux density around the sensor exceeds a certain threshold, it generates voltage, triggering a device to send a large amount of current through the coils in the coil pack. This magnetic flux is created by a rotating magnet on the distributor shaft. The impact to the spark plugs themselves is the same.

[[File:Halleffectsensor.gif]] [[File:Mag26.gif]]

===A Mathematical Model===

The primary physics equation used when analyzing spark plugs is Faraday's Law, which states <math>\mathcal{E} = -{{d\Phi_B} \over dt} \ </math>, where <math>\mathcal{E}</math> is the electromotive force(EMF) produced from the time-varying magnetic flux Φ''B''. The flux is given by <math> \int_{\Sigma} \mathbf{B} \cdot d\mathbf{A}. </math>

[[File:Faraday+s+Law+and+Ignition.jpg|500px]]

The basic equation for dielectric breakdown is given as <math>{{V_d}_b}= {{E_d}_sd}</math>

V''db'' represents the dielectric breakdown voltage and E''ds'' represents the dielectric strength of the insulator and d is the distance. The dielectric strength of air is 3x10^6 V/m, so at a gap of 1mm, the required voltage for dielectric breakdown is 30,000V.

That is a good model for the spark outside of an engine at ambient temperature but there are other variables to consider for voltage required inside of the engine because the dielectric strength will change. If it is assumed the spark plugs have no sort of buildup from carbon or oil, the other variables that effect dielectric breakdown voltage are electrical frequency, temperature, the fact that the dielectric material is not just air but a mixture of gasoline and air at a specific ratio, plus the shape, size, and thickness of the electrodes of the spark plug. The temperature inside of the combustion chamber is typically around 1500 degrees Celcius, increased temperature decreases the dielectric strength. Increased electrical frequency decreases the dielectric strength which is why some manufacturers have researched using higher frequency ignition systems. Gasoline's chemical makeup can vary but Benzene, a component of gasoline, has a dielectric strength of 163x10^6 V/m which is much higher than the dielectric strength of air.

===Further Explanation of System===

[https://www.youtube.com/watch?v=__FRCSvEYdE Ignition System Function]
[https://www.youtube.com/watch?v=sFiGsCkAMbk Description of Spark Plug]

==Examples==

http://vicsauto.net/images/anatomy_sparkplug.JPG

Anatomy of a Typical Spark Plug

https://media.boingboing.net/wp-content/uploads/2015/06/skd282544sdc_XS.jpg

Firing Spark Plug

Ex. A spark plug in a car has electrodes separated by a gap of 0.025in. To create a spark and ignite the air-fuel mixture in the engine, an electric field of 3.0x10^6 V/m is required in the gap.
a) What potential difference must be applied to the spark plug to initiate a spark?
b) If the separation between electrodes is increased, does the required potential difference increase, decrease, or stay the same? Explain.
c) Find the potential difference for a separation of 0.050 in.

[[File:Spark_plug_problem-page-001.jpg|400px]]

[[File:Spark_plug_problem-page-002.jpg|400px]]

==Connectedness==
Spark Plugs allow gasoline engines to run. The heat from the spark generated by the ignition system causes the gasoline to combust and drive the piston away to turn the crankshaft. This only works if the spark's heat is above the flashpoint of the fuel. Gasoline has a relatively low flashpoint while diesel has a relatively high flashpoint which is why gasoline engines operate at lower pressures with and with spark plugs (spark ignition) and diesels operate at much higher pressures with no spark (compression ignition). Those concepts would apply more so in a course covering thermodynamics. I am a DIY mechanic who works on both gasoline and diesel engines so understanding the physics behind the ignition system of an engine is useful for my tinkering and modifications of the vehicles I work on. A spark ignition system is mostly related to electrical engineering but as it's fundamental concepts are fairly basic in terms of electrical engineering, they are covered in the mechanical engineering curriculum. The stresses, forces and heat generated by combustion are certainly integral concepts of the mechanical engineering curriculum.

Editor 2: I also do extensive mechanic and repair work on both gasoline and diesel engines. I've interned for Cummins Engines and want to pursue a career developing performance engines for racing applications, so understanding the physics behind spark plugs and ignition systems and how this integrates within engine performance is extremely important. As a Powertrain member for GT Motorsports, understanding these concepts is critical to component design and development for competition success.

==History==
Spark plugs have been around since at least 1859. There are reports that a rudimentary version of the spark plug was originally invented by an African-American man by the name of Edmond Berger in 1839 but he did not patent it. Spark ignition was first used in an early internal combustion engine created by Belgian inventor Étienne Lenoir in 1859. British physicist Sir Oliver Lodge provided many improvements to the design in the 1880s. At the turn of the century, many patents for spark plugs were filed by Nikola Tesla, Robert Bosch, Frederick Richard Simms but Bosch is usually credited with the first commercially viable high-voltage spark plugs (1802) and Albert Champion is credited with expanding its use when he built a spark plug factory in Boston in 1805 and supplied American automobile manufacturers. Sir Oliver Lodge's children started Lodge Plug Company in Britain which allowed the British automobile industry to take off. Similarly, Bosch's spark plugs were largely used by automobile manufacturers in mainland Europe.

Throughout the years, improvements have been made such as adding resistors to the plugs to decrease radio interference, different electrode materials, and the ignition system itself has moved from points and distributors to electronic controllers. Spark plugs have been used in things other than internal combustion engines, such as the second and third stages of the Saturn V rocket.

== See also ==

[http://www.physicsbook.gatech.edu/Magnetic_Field_of_a_Solenoid Magnetic Field of a Solenoid]

[http://www.physicsbook.gatech.edu/Curly_Electric_Fields Curly Electric Fields]

[http://www.physicsbook.gatech.edu/Faraday%27s_Law Faraday's Law]

[http://www.physicsbook.gatech.edu/Inductance Inductance]

[http://www.physicsbook.gatech.edu/Transformers_from_a_physics_standpoint Transformers]

===External links===

[http://www.ngk.com.au/spark-plugs/technical-information/spark-plug-anatomy-construction Spark Plug Anatomy]

==References==

http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/ignition.html

http://auto.howstuffworks.com/spark-plugs.htm

https://www.youtube.com/watch?v=b2udCm7DMzU

http://physics.info/dielectrics/

http://www.engineeringtoolbox.com/liquid-dielectric-constants-d_1263.html

http://www.themotormuseuminminiature.co.uk/inv-jeanjoseph-etienne-lenoir.php

https://www.hemmings.com/magazine/hcc/2006/01/Albert-Champion/1281809.html

http://www.kisouman.com/spark_plug_description-1071.html

http://mechanicstips.blogspot.com/2015/06/how-four-stroke-cycle-engine-works.html

http://www.gsparkplug.com/shop/how-spark-plugs-work/

http://www.mech4study.com/2017/03/magneto-ignition-system-parts-function-working-advantages-and-disadvantages.html

https://www.slideshare.net/jesscar/piston-engines-ignition

http://www.electronics-tutorials.ws/electromagnetism/hall-effect.html

[[Category:Real Life Applications of Electromagnetic Principles]]

Spark Plugs

2017-11-28T23:22:06Z

Gellis9:

Claimed By Christopher Skretkowicz
Claimed By Edward Mauger Spring 2017
'''Claimed By Geraghty Anne Ellis Fall 2017 (Edits)'''

This page chronicles the inner workings and hidden mechanisms involved with spark plug applications, and their integration with automotive ignition systems in the real world.

==Basic Engine Theory==

In order to understand how spark plugs work, there must be some background explanation for the systems that use them. Internal combustion engines are those that rely on the ignition of the air-fuel mixture to create the energy used to power most modern vehicles. [The different types [https://en.wikipedia.org/wiki/Two-stroke_engine two-stroke] and four-stroke. [https://auto.howstuffworks.com/rotary-engine4.htm Rotary engines] use the four-stroke cycle but accomplish combustion much differently. Spark plugs are used in all aforementioned applications for the same purpose. For simplicity, the four-stroke IC engine will be discussed in slightly more detail.

There are four main phases or "strokes" for each combustion chamber of the four-stroke engine: intake, compression, power, and exhaust. Regardless of how many cylinders, all of these engines have a firing order - order of which spark plugs are ignited. This sequential order, rather than all firing at once, allows for the continuous motion of the crankshaft.

[[File:IC_engine.jpg]]

[[File:4-Stroke-Engine-with-airflows.gif]] [[File:enginefiringorder.gif]]

===Intake===

Air is pulled into the engine from the environment by the air intake and stored in the plenum. From the plenum, air enters the intake manifold where fuel injectors will distribute the proper ratio of fuel to the amount of air. Naturally aspirated engines (no turbos, superchargers or anything used to force more air into the engine) typically run at a 14:1 air/fuel ratio. The intake manifold is bolted directly onto the engine so that this mixture can enter the combustion chamber or bore. Intake valves during seal the opening to the chamber on the intake side of the engine; during this phase or "stroke" however, they are opened to allow the air-fuel mixture into the bore. [https://en.wikipedia.org/wiki/Piston Pisons], which travel up and down the bore and connected to the crankshaft (see below), are towards the bottom of the bore during this stroke to allow for the most air to enter the combustion chamber and will reach [https://en.wikipedia.org/wiki/Dead_centre_(engineering)#Reciprocating_engine BDC or bottom dead center].

[[File:Ferrari_air_intake_system.jpg|400px]]

[https://en.wikipedia.org/wiki/Camshaft Camshafts] are used to control when these valves(both intake and exhaust, which will be discussed later) open and close and are directly connected to the [https://en.wikipedia.org/wiki/Crankshaft crankshaft], which in short translate the reciprocating motion of the engine to rotational motion which will eventually be translated through the drivetrain to [https://itstillruns.com/car-move-5104221.html propell the vehicle forward.]

===Compression===

In this stroke, the piston moves to the top of the bore, compressing the air-fuel mixture. Both intake and exhaust valves are shut to not allow for any air to escape. Compressing the mixture enables more energy to be expelled when it is ignited and generates heat, which enables the combustion process to happen more quickly after the mixture is ignited. This process follows the ideal gas law in that as pressure is increased and volume decreased, so must the temperature increase.

===Power===

During the power stroke, just before the piston reaches TDC, or top dead center (the very top of the bore), the spark plug ignites creating a combustion reaction. This explosion forces the piston downwards, and so the crankshaft continues to rotate.

===Exhaust===

With the piston moving back up the bore, what remains of the air-fuel mixture after combustion is no longer needed. The camshaft allows the exhaust valve to open and these exhaust gases are pushed out of the combustion chamber through the exhaust manifold, into the [https://en.wikipedia.org/wiki/Catalytic_converter catalytic converter] to lessen the amount of pollution produced, through the [https://en.wikipedia.org/wiki/Muffler muffler] to lessen the noise emitted, and out the tailpipe into the environment.
Back inside the engine, the exhaust valve closes and the intake stroke begins again.

[[File:Exhaust_system.jpg]]

==The Main Idea==

Spark plugs are essentially what their namesake says they are: plugs that screw into the cylinders of an engine and produce sparks that ignite fuel in combustion engines during the power stroke. Spark plugs take advantage of Faraday's Law and induction to create large spikes of voltage, typically around 40,000 V, across an electrode gap that would otherwise be impossible to achieve with a regular 12 volt car battery. Their two main functions are to produce spark and to remove heat from the combustion chamber.

[[File:Spark_plug.gif]]

===Mechanical Ignition===

Automotive ignition systems are either mechanically or electrically timed and powered by a 12V battery. A mechanically timed ignition system contains a distributor, coil pack, spark plugs, and wires.

[[File:220px-Car_ignition_system.svg.png]]

Each coil in the coil pack consists of a primary winding and a secondary winding, which share a common magnetic core. Both coils are connected to the battery. Additionally, the primary is connected to the distributor and the secondary coil is connected to the spark plugs through the cap and rotor within the distributor. The secondary winding has more turns in its coil, resulting in a much higher voltage that runs through it.

[[File:CarDistributor.jpg|250px]] [[File:Ls2_coil_schematic.jpg|250px]]

Initially, the [https://en.wikipedia.org/wiki/Contact_breaker contact breaker] is closed, completing the circuit and allowing current to flow from the battery, through the primary coil and contact breaker and back through the battery. This flow of current creates a [http://www.physicsbook.gatech.edu/Magnetic_field magnetic field] in the primary's core. The distributor shaft is attached to the camshaft lobes, which dictate when the contact breaker is open or closed. If open, without the current flow, there is no magnetic field. Because this connection is dependent on the cams, there is a cyclical repetition of the existence of a magnetic field. The rapid change of this field causes a large change in [http://www.physicsbook.gatech.edu/Magnetic_Flux magnetic flux]. According to [http://www.physicsbook.gatech.edu/Faraday%27s_Law Faraday's Law], this change in magnetic flux will cause a curly electric field which will induce a large voltage that will be crucial to spark plug function.

[[File:magneticfieldIgsyst.jpg|400px]]

Because the primary coil is wrapped around the secondary coil, a varying magnetic field induces an electric current to be run through the secondary coil, which in turn produces a much larger EMF due to the number of loops in the coil. This will take the inputted DC voltage (again, typically 12-24V) and output 15,000V-40,000V AC. That current is fed to the spark plugs, which have a center electrode that is isolated from grounding electrode, grounded through the spark plug casing to the engine, which shares a ground with the coil. The two electrodes have a gap between them that is set typically between .4mm and 1.7mm. A smaller gap requires less voltage from the coil, a larger gap requires more voltage from the coil. In this case, the spark plug's electrodes act as a capacitor with the air in the cylinder being a dielectric insulator. For a spark to occur, the voltage from the coil must be sufficient to cause dielectric breakdown of the air. As the current crosses the electrodes, there is a drastic raise in the temperature upwards of 60,000K, creating a small spark. When this happens, a click from the spark plug can be heard. This spark ignites the air-fuel mixture in the cylinder continuing the crankshaft motion. The distributor cap and rotor determine which cylinder receives a spark to match the firing order.

===Electronic Ignition===

An electronic ignition system, common among modern cars, solves some of the flaws of the mechanical system: wear, oxidation, and contact of breaker points. Angular sensors replace these breaker points and tell the [https://en.wikipedia.org/wiki/Engine_control_unit engine control unit(ECU)].

[[File:ElectronicIgnitionSystem.jpg]]

A common example, Hall effect sensors, relies on magnetic fields to send signals to the ECU. (See [http://www.physicsbook.gatech.edu/Hall_Effect Hall Effect] for more in-depth information on the fundamental principles behind this). Once the magnetic flux density around the sensor exceeds a certain threshold, it generates voltage, triggering a device to send a large amount of current through the coils in the coil pack. This magnetic flux is created by a rotating magnet on the distributor shaft. The impact to the spark plugs themselves is the same.

[[File:Halleffectsensor.gif]] [[File:Mag26.gif]]

===A Mathematical Model===

The primary physics equation used when analyzing spark plugs is Faraday's Law, which states <math>\mathcal{E} = -{{d\Phi_B} \over dt} \ </math>, where <math>\mathcal{E}</math> is the electromotive force(EMF) produced from the time-varying magnetic flux Φ''B''. The flux is given by <math> \int_{\Sigma} \mathbf{B} \cdot d\mathbf{A}. </math>

[[File:Faraday+s+Law+and+Ignition.jpg|500px]]

The basic equation for dielectric breakdown is given as <math>{{V_d}_b}= {{E_d}_sd}</math>

V''db'' represents the dielectric breakdown voltage and E''ds'' represents the dielectric strength of the insulator and d is the distance. The dielectric strength of air is 3x10^6 V/m, so at a gap of 1mm, the required voltage for dielectric breakdown is 30,000V.

That is a good model for the spark outside of an engine at ambient temperature but there are other variables to consider for voltage required inside of the engine because the dielectric strength will change. If it is assumed the spark plugs have no sort of buildup from carbon or oil, the other variables that effect dielectric breakdown voltage are electrical frequency, temperature, the fact that the dielectric material is not just air but a mixture of gasoline and air at a specific ratio, plus the shape, size, and thickness of the electrodes of the spark plug. The temperature inside of the combustion chamber is typically around 1500 degrees Celcius, increased temperature decreases the dielectric strength. Increased electrical frequency decreases the dielectric strength which is why some manufacturers have researched using higher frequency ignition systems. Gasoline's chemical makeup can vary but Benzene, a component of gasoline, has a dielectric strength of 163x10^6 V/m which is much higher than the dielectric strength of air.

===Further Explanation of System===

[https://www.youtube.com/watch?v=__FRCSvEYdE Ignition System Function]
[https://www.youtube.com/watch?v=sFiGsCkAMbk Description of Spark Plug]

==Examples==

http://vicsauto.net/images/anatomy_sparkplug.JPG

Anatomy of a Typical Spark Plug

https://media.boingboing.net/wp-content/uploads/2015/06/skd282544sdc_XS.jpg

Firing Spark Plug

Ex. A spark plug in a car has electrodes separated by a gap of 0.025in. To create a spark and ignite the air-fuel mixture in the engine, an electric field of 3.0x10^6 V/m is required in the gap.
a) What potential difference must be applied to the spark plug to initiate a spark?
b) If the separation between electrodes is increased, does the required potential difference increase, decrease, or stay the same? Explain.
c) Find the potential difference for a separation of 0.050 in.

[[File:Spark_plug_problem-page-001.jpg]]

[[File:Spark_plug_problem-page-002.jpg]]

==Connectedness==
Spark Plugs allow gasoline engines to run. The heat from the spark generated by the ignition system causes the gasoline to combust and drive the piston away to turn the crankshaft. This only works if the spark's heat is above the flashpoint of the fuel. Gasoline has a relatively low flashpoint while diesel has a relatively high flashpoint which is why gasoline engines operate at lower pressures with and with spark plugs (spark ignition) and diesels operate at much higher pressures with no spark (compression ignition). Those concepts would apply more so in a course covering thermodynamics. I am a DIY mechanic who works on both gasoline and diesel engines so understanding the physics behind the ignition system of an engine is useful for my tinkering and modifications of the vehicles I work on. A spark ignition system is mostly related to electrical engineering but as it's fundamental concepts are fairly basic in terms of electrical engineering, they are covered in the mechanical engineering curriculum. The stresses, forces and heat generated by combustion are certainly integral concepts of the mechanical engineering curriculum.

Editor 2: I also do extensive mechanic and repair work on both gasoline and diesel engines. I've interned for Cummins Engines and want to pursue a career developing performance engines for racing applications, so understanding the physics behind spark plugs and ignition systems and how this integrates within engine performance is extremely important. As a Powertrain member for GT Motorsports, understanding these concepts is critical to component design and development for competition success.

==History==
Spark plugs have been around since at least 1859. There are reports that a rudimentary version of the spark plug was originally invented by an African-American man by the name of Edmond Berger in 1839 but he did not patent it. Spark ignition was first used in an early internal combustion engine created by Belgian inventor Étienne Lenoir in 1859. British physicist Sir Oliver Lodge provided many improvements to the design in the 1880s. At the turn of the century, many patents for spark plugs were filed by Nikola Tesla, Robert Bosch, Frederick Richard Simms but Bosch is usually credited with the first commercially viable high-voltage spark plugs (1802) and Albert Champion is credited with expanding its use when he built a spark plug factory in Boston in 1805 and supplied American automobile manufacturers. Sir Oliver Lodge's children started Lodge Plug Company in Britain which allowed the British automobile industry to take off. Similarly, Bosch's spark plugs were largely used by automobile manufacturers in mainland Europe.

Throughout the years, improvements have been made such as adding resistors to the plugs to decrease radio interference, different electrode materials, and the ignition system itself has moved from points and distributors to electronic controllers. Spark plugs have been used in things other than internal combustion engines, such as the second and third stages of the Saturn V rocket.

== See also ==

[http://www.physicsbook.gatech.edu/Magnetic_Field_of_a_Solenoid Magnetic Field of a Solenoid]

[http://www.physicsbook.gatech.edu/Curly_Electric_Fields Curly Electric Fields]

[http://www.physicsbook.gatech.edu/Faraday%27s_Law Faraday's Law]

[http://www.physicsbook.gatech.edu/Inductance Inductance]

[http://www.physicsbook.gatech.edu/Transformers_from_a_physics_standpoint Transformers]

===External links===

[http://www.ngk.com.au/spark-plugs/technical-information/spark-plug-anatomy-construction Spark Plug Anatomy]

==References==

http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/ignition.html

http://auto.howstuffworks.com/spark-plugs.htm

https://www.youtube.com/watch?v=b2udCm7DMzU

http://physics.info/dielectrics/

http://www.engineeringtoolbox.com/liquid-dielectric-constants-d_1263.html

http://www.themotormuseuminminiature.co.uk/inv-jeanjoseph-etienne-lenoir.php

https://www.hemmings.com/magazine/hcc/2006/01/Albert-Champion/1281809.html

http://www.kisouman.com/spark_plug_description-1071.html

http://mechanicstips.blogspot.com/2015/06/how-four-stroke-cycle-engine-works.html

http://www.gsparkplug.com/shop/how-spark-plugs-work/

http://www.mech4study.com/2017/03/magneto-ignition-system-parts-function-working-advantages-and-disadvantages.html

https://www.slideshare.net/jesscar/piston-engines-ignition

http://www.electronics-tutorials.ws/electromagnetism/hall-effect.html

[[Category:Real Life Applications of Electromagnetic Principles]]

File:Spark plug problem-page-002.jpg

2017-11-28T23:21:59Z

Gellis9:

File:Spark plug problem-page-001.jpg

2017-11-28T23:21:22Z

Gellis9:

Spark Plugs

2017-11-28T23:07:07Z

Gellis9:

Claimed By Christopher Skretkowicz
Claimed By Edward Mauger Spring 2017
'''Claimed By Geraghty Anne Ellis Fall 2017 (Edits)'''

This page chronicles the inner workings and hidden mechanisms involved with spark plug applications, and their integration with automotive ignition systems in the real world.

==Basic Engine Theory==

In order to understand how spark plugs work, there must be some background explanation for the systems that use them. Internal combustion engines are those that rely on the ignition of the air-fuel mixture to create the energy used to power most modern vehicles. [The different types [https://en.wikipedia.org/wiki/Two-stroke_engine two-stroke] and four-stroke. [https://auto.howstuffworks.com/rotary-engine4.htm Rotary engines] use the four-stroke cycle but accomplish combustion much differently. Spark plugs are used in all aforementioned applications for the same purpose. For simplicity, the four-stroke IC engine will be discussed in slightly more detail.

There are four main phases or "strokes" for each combustion chamber of the four-stroke engine: intake, compression, power, and exhaust. Regardless of how many cylinders, all of these engines have a firing order - order of which spark plugs are ignited. This sequential order, rather than all firing at once, allows for the continuous motion of the crankshaft.

[[File:IC_engine.jpg]]

[[File:4-Stroke-Engine-with-airflows.gif]] [[File:enginefiringorder.gif]]

===Intake===

Air is pulled into the engine from the environment by the air intake and stored in the plenum. From the plenum, air enters the intake manifold where fuel injectors will distribute the proper ratio of fuel to the amount of air. Naturally aspirated engines (no turbos, superchargers or anything used to force more air into the engine) typically run at a 14:1 air/fuel ratio. The intake manifold is bolted directly onto the engine so that this mixture can enter the combustion chamber or bore. Intake valves during seal the opening to the chamber on the intake side of the engine; during this phase or "stroke" however, they are opened to allow the air-fuel mixture into the bore. [https://en.wikipedia.org/wiki/Piston Pisons], which travel up and down the bore and connected to the crankshaft (see below), are towards the bottom of the bore during this stroke to allow for the most air to enter the combustion chamber and will reach [https://en.wikipedia.org/wiki/Dead_centre_(engineering)#Reciprocating_engine BDC or bottom dead center].

[[File:Ferrari_air_intake_system.jpg|400px]]

[https://en.wikipedia.org/wiki/Camshaft Camshafts] are used to control when these valves(both intake and exhaust, which will be discussed later) open and close and are directly connected to the [https://en.wikipedia.org/wiki/Crankshaft crankshaft], which in short translate the reciprocating motion of the engine to rotational motion which will eventually be translated through the drivetrain to [https://itstillruns.com/car-move-5104221.html propell the vehicle forward.]

===Compression===

In this stroke, the piston moves to the top of the bore, compressing the air-fuel mixture. Both intake and exhaust valves are shut to not allow for any air to escape. Compressing the mixture enables more energy to be expelled when it is ignited and generates heat, which enables the combustion process to happen more quickly after the mixture is ignited. This process follows the ideal gas law in that as pressure is increased and volume decreased, so must the temperature increase.

===Power===

During the power stroke, just before the piston reaches TDC, or top dead center (the very top of the bore), the spark plug ignites creating a combustion reaction. This explosion forces the piston downwards, and so the crankshaft continues to rotate.

===Exhaust===

With the piston moving back up the bore, what remains of the air-fuel mixture after combustion is no longer needed. The camshaft allows the exhaust valve to open and these exhaust gases are pushed out of the combustion chamber through the exhaust manifold, into the [https://en.wikipedia.org/wiki/Catalytic_converter catalytic converter] to lessen the amount of pollution produced, through the [https://en.wikipedia.org/wiki/Muffler muffler] to lessen the noise emitted, and out the tailpipe into the environment.
Back inside the engine, the exhaust valve closes and the intake stroke begins again.

[[File:Exhaust_system.jpg]]

==The Main Idea==

Spark plugs are essentially what their namesake says they are: plugs that screw into the cylinders of an engine and produce sparks that ignite fuel in combustion engines during the power stroke. Spark plugs take advantage of Faraday's Law and induction to create large spikes of voltage, typically around 40,000 V, across an electrode gap that would otherwise be impossible to achieve with a regular 12 volt car battery. Their two main functions are to produce spark and to remove heat from the combustion chamber.

[[File:Spark_plug.gif]]

===Mechanical Ignition===

Automotive ignition systems are either mechanically or electrically timed and powered by a 12V battery. A mechanically timed ignition system contains a distributor, coil pack, spark plugs, and wires.

[[File:220px-Car_ignition_system.svg.png]]

Each coil in the coil pack consists of a primary winding and a secondary winding, which share a common magnetic core. Both coils are connected to the battery. Additionally, the primary is connected to the distributor and the secondary coil is connected to the spark plugs through the cap and rotor within the distributor. The secondary winding has more turns in its coil, resulting in a much higher voltage that runs through it.

[[File:CarDistributor.jpg|250px]] [[File:Ls2_coil_schematic.jpg|250px]]

Initially, the [https://en.wikipedia.org/wiki/Contact_breaker contact breaker] is closed, completing the circuit and allowing current to flow from the battery, through the primary coil and contact breaker and back through the battery. This flow of current creates a [http://www.physicsbook.gatech.edu/Magnetic_field magnetic field] in the primary's core. The distributor shaft is attached to the camshaft lobes, which dictate when the contact breaker is open or closed. If open, without the current flow, there is no magnetic field. Because this connection is dependent on the cams, there is a cyclical repetition of the existence of a magnetic field. The rapid change of this field causes a large change in [http://www.physicsbook.gatech.edu/Magnetic_Flux magnetic flux]. According to [http://www.physicsbook.gatech.edu/Faraday%27s_Law Faraday's Law], this change in magnetic flux will cause a curly electric field which will induce a large voltage that will be crucial to spark plug function.

[[File:magneticfieldIgsyst.jpg|400px]]

Because the primary coil is wrapped around the secondary coil, a varying magnetic field induces an electric current to be run through the secondary coil, which in turn produces a much larger EMF due to the number of loops in the coil. This will take the inputted DC voltage (again, typically 12-24V) and output 15,000V-40,000V AC. That current is fed to the spark plugs, which have a center electrode that is isolated from grounding electrode, grounded through the spark plug casing to the engine, which shares a ground with the coil. The two electrodes have a gap between them that is set typically between .4mm and 1.7mm. A smaller gap requires less voltage from the coil, a larger gap requires more voltage from the coil. In this case, the spark plug's electrodes act as a capacitor with the air in the cylinder being a dielectric insulator. For a spark to occur, the voltage from the coil must be sufficient to cause dielectric breakdown of the air. As the current crosses the electrodes, there is a drastic raise in the temperature upwards of 60,000K, creating a small spark. When this happens, a click from the spark plug can be heard. This spark ignites the air-fuel mixture in the cylinder continuing the crankshaft motion. The distributor cap and rotor determine which cylinder receives a spark to match the firing order.

===Electronic Ignition===

An electronic ignition system, common among modern cars, solves some of the flaws of the mechanical system: wear, oxidation, and contact of breaker points. Angular sensors replace these breaker points and tell the [https://en.wikipedia.org/wiki/Engine_control_unit engine control unit(ECU)].

[[File:ElectronicIgnitionSystem.jpg]]

A common example, Hall effect sensors, relies on magnetic fields to send signals to the ECU. (See [http://www.physicsbook.gatech.edu/Hall_Effect Hall Effect] for more in-depth information on the fundamental principles behind this). Once the magnetic flux density around the sensor exceeds a certain threshold, it generates voltage, triggering a device to send a large amount of current through the coils in the coil pack. This magnetic flux is created by a rotating magnet on the distributor shaft. The impact to the spark plugs themselves is the same.

[[File:Halleffectsensor.gif]] [[File:Mag26.gif]]

===A Mathematical Model===

The primary physics equation used when analyzing spark plugs is Faraday's Law, which states <math>\mathcal{E} = -{{d\Phi_B} \over dt} \ </math>, where <math>\mathcal{E}</math> is the electromotive force(EMF) produced from the time-varying magnetic flux Φ''B''. The flux is given by <math> \int_{\Sigma} \mathbf{B} \cdot d\mathbf{A}. </math>

[[File:Faraday+s+Law+and+Ignition.jpg|500px]]

The basic equation for dielectric breakdown is given as <math>{{V_d}_b}= {{E_d}_sd}</math>

V''db'' represents the dielectric breakdown voltage and E''ds'' represents the dielectric strength of the insulator and d is the distance. The dielectric strength of air is 3x10^6 V/m, so at a gap of 1mm, the required voltage for dielectric breakdown is 30,000V.

That is a good model for the spark outside of an engine at ambient temperature but there are other variables to consider for voltage required inside of the engine because the dielectric strength will change. If it is assumed the spark plugs have no sort of buildup from carbon or oil, the other variables that effect dielectric breakdown voltage are electrical frequency, temperature, the fact that the dielectric material is not just air but a mixture of gasoline and air at a specific ratio, plus the shape, size, and thickness of the electrodes of the spark plug. The temperature inside of the combustion chamber is typically around 1500 degrees Celcius, increased temperature decreases the dielectric strength. Increased electrical frequency decreases the dielectric strength which is why some manufacturers have researched using higher frequency ignition systems. Gasoline's chemical makeup can vary but Benzene, a component of gasoline, has a dielectric strength of 163x10^6 V/m which is much higher than the dielectric strength of air.

===Further Explanation of System===

[https://www.youtube.com/watch?v=__FRCSvEYdE Ignition System Function]
[https://www.youtube.com/watch?v=sFiGsCkAMbk Description of Spark Plug]

==Examples==

http://vicsauto.net/images/anatomy_sparkplug.JPG

Anatomy of a Typical Spark Plug

https://media.boingboing.net/wp-content/uploads/2015/06/skd282544sdc_XS.jpg

Firing Spark Plug

==Connectedness==
Spark Plugs allow gasoline engines to run. The heat from the spark generated by the ignition system causes the gasoline to combust and drive the piston away to turn the crankshaft. This only works if the spark's heat is above the flashpoint of the fuel. Gasoline has a relatively low flashpoint while diesel has a relatively high flashpoint which is why gasoline engines operate at lower pressures with and with spark plugs (spark ignition) and diesels operate at much higher pressures with no spark (compression ignition). Those concepts would apply more so in a course covering thermodynamics. I am a DIY mechanic who works on both gasoline and diesel engines so understanding the physics behind the ignition system of an engine is useful for my tinkering and modifications of the vehicles I work on. A spark ignition system is mostly related to electrical engineering but as it's fundamental concepts are fairly basic in terms of electrical engineering, they are covered in the mechanical engineering curriculum. The stresses, forces and heat generated by combustion are certainly integral concepts of the mechanical engineering curriculum.

Editor 2: I also do extensive mechanic and repair work on both gasoline and diesel engines. I've interned for Cummins Engines and want to pursue a career developing performance engines for racing applications, so understanding the physics behind spark plugs and ignition systems and how this integrates within engine performance is extremely important. As a Powertrain member for GT Motorsports, understanding these concepts is critical to component design and development for competition success.

==History==
Spark plugs have been around since at least 1859. There are reports that a rudimentary version of the spark plug was originally invented by an African-American man by the name of Edmond Berger in 1839 but he did not patent it. Spark ignition was first used in an early internal combustion engine created by Belgian inventor Étienne Lenoir in 1859. British physicist Sir Oliver Lodge provided many improvements to the design in the 1880s. At the turn of the century, many patents for spark plugs were filed by Nikola Tesla, Robert Bosch, Frederick Richard Simms but Bosch is usually credited with the first commercially viable high-voltage spark plugs (1802) and Albert Champion is credited with expanding its use when he built a spark plug factory in Boston in 1805 and supplied American automobile manufacturers. Sir Oliver Lodge's children started Lodge Plug Company in Britain which allowed the British automobile industry to take off. Similarly, Bosch's spark plugs were largely used by automobile manufacturers in mainland Europe.

Throughout the years, improvements have been made such as adding resistors to the plugs to decrease radio interference, different electrode materials, and the ignition system itself has moved from points and distributors to electronic controllers. Spark plugs have been used in things other than internal combustion engines, such as the second and third stages of the Saturn V rocket.

== See also ==

[http://www.physicsbook.gatech.edu/Magnetic_Field_of_a_Solenoid Magnetic Field of a Solenoid]

[http://www.physicsbook.gatech.edu/Curly_Electric_Fields Curly Electric Fields]

[http://www.physicsbook.gatech.edu/Faraday%27s_Law Faraday's Law]

[http://www.physicsbook.gatech.edu/Inductance Inductance]

[http://www.physicsbook.gatech.edu/Transformers_from_a_physics_standpoint Transformers]

===External links===

[http://www.ngk.com.au/spark-plugs/technical-information/spark-plug-anatomy-construction Spark Plug Anatomy]

==References==

http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/ignition.html

http://auto.howstuffworks.com/spark-plugs.htm

https://www.youtube.com/watch?v=b2udCm7DMzU

http://physics.info/dielectrics/

http://www.engineeringtoolbox.com/liquid-dielectric-constants-d_1263.html

http://www.themotormuseuminminiature.co.uk/inv-jeanjoseph-etienne-lenoir.php

https://www.hemmings.com/magazine/hcc/2006/01/Albert-Champion/1281809.html

http://www.kisouman.com/spark_plug_description-1071.html

http://mechanicstips.blogspot.com/2015/06/how-four-stroke-cycle-engine-works.html

http://www.gsparkplug.com/shop/how-spark-plugs-work/

http://www.mech4study.com/2017/03/magneto-ignition-system-parts-function-working-advantages-and-disadvantages.html

https://www.slideshare.net/jesscar/piston-engines-ignition

http://www.electronics-tutorials.ws/electromagnetism/hall-effect.html

[[Category:Real Life Applications of Electromagnetic Principles]]

Spark Plugs

2017-11-28T23:01:59Z

Gellis9:

Claimed By Christopher Skretkowicz
Claimed By Edward Mauger Spring 2017
'''Claimed By Geraghty Anne Ellis Fall 2017 (Edits)'''

This page chronicles the inner workings and hidden mechanisms involved with spark plug applications, and their integration with automotive ignition systems in the real world.

==Basic Engine Theory==

In order to understand how spark plugs work, there must be some background explanation for the systems that use them. Internal combustion engines are those that rely on the ignition of the air-fuel mixture to create the energy used to power most modern vehicles. [The different types [https://en.wikipedia.org/wiki/Two-stroke_engine two-stroke] and four-stroke. [https://auto.howstuffworks.com/rotary-engine4.htm Rotary engines] use the four-stroke cycle but accomplish combustion much differently. Spark plugs are used in all aforementioned applications for the same purpose. For simplicity, the four-stroke IC engine will be discussed in slightly more detail.

There are four main phases or "strokes" for each combustion chamber of the four-stroke engine: intake, compression, power, and exhaust. Regardless of how many cylinders, all of these engines have a firing order - order of which spark plugs are ignited. This sequential order, rather than all firing at once, allows for the continuous motion of the crankshaft.

[[File:IC_engine.jpg]]

[[File:4-Stroke-Engine-with-airflows.gif]] [[File:enginefiringorder.gif]]

===Intake===

Air is pulled into the engine from the environment by the air intake and stored in the plenum. From the plenum, air enters the intake manifold where fuel injectors will distribute the proper ratio of fuel to the amount of air. Naturally aspirated engines (no turbos, superchargers or anything used to force more air into the engine) typically run at a 14:1 air/fuel ratio. The intake manifold is bolted directly onto the engine so that this mixture can enter the combustion chamber or bore. Intake valves during seal the opening to the chamber on the intake side of the engine; during this phase or "stroke" however, they are opened to allow the air-fuel mixture into the bore. [https://en.wikipedia.org/wiki/Piston Pisons], which travel up and down the bore and connected to the crankshaft (see below), are towards the bottom of the bore during this stroke to allow for the most air to enter the combustion chamber and will reach [https://en.wikipedia.org/wiki/Dead_centre_(engineering)#Reciprocating_engine BDC or bottom dead center].

[[File:Ferrari_air_intake_system.jpg|400px]]

[https://en.wikipedia.org/wiki/Camshaft Camshafts] are used to control when these valves(both intake and exhaust, which will be discussed later) open and close and are directly connected to the [https://en.wikipedia.org/wiki/Crankshaft crankshaft], which in short translate the reciprocating motion of the engine to rotational motion which will eventually be translated through the drivetrain to [https://itstillruns.com/car-move-5104221.html propell the vehicle forward.]

===Compression===

In this stroke, the piston moves to the top of the bore, compressing the air-fuel mixture. Both intake and exhaust valves are shut to not allow for any air to escape. Compressing the mixture enables more energy to be expelled when it is ignited and generates heat, which enables the combustion process to happen more quickly after the mixture is ignited. This process follows the ideal gas law in that as pressure is increased and volume decreased, so must the temperature increase.

===Power===

During the power stroke, just before the piston reaches TDC, or top dead center (the very top of the bore), the spark plug ignites creating a combustion reaction. This explosion forces the piston downwards, and so the crankshaft continues to rotate.

===Exhaust===

With the piston moving back up the bore, what remains of the air-fuel mixture after combustion is no longer needed. The camshaft allows the exhaust valve to open and these exhaust gases are pushed out of the combustion chamber through the exhaust manifold, into the [https://en.wikipedia.org/wiki/Catalytic_converter catalytic converter] to lessen the amount of pollution produced, through the [https://en.wikipedia.org/wiki/Muffler muffler] to lessen the noise emitted, and out the tailpipe into the environment.
Back inside the engine, the exhaust valve closes and the intake stroke begins again.

[[File:Exhaust_system.jpg]]

==The Main Idea==

Spark plugs are essentially what their namesake says they are: plugs that screw into the cylinders of an engine and produce sparks that ignite fuel in combustion engines during the power stroke. Spark plugs take advantage of Faraday's Law and induction to create large spikes of voltage, typically around 40,000 V, across an electrode gap that would otherwise be impossible to achieve with a regular 12 volt car battery. Their two main functions are to produce spark and to remove heat from the combustion chamber.

[[File:Spark_plug.gif]]

===Mechanical Ignition===

Automotive ignition systems are either mechanically or electrically timed and powered by a 12V battery. A mechanically timed ignition system contains a distributor, coil pack, spark plugs, and wires.

[[File:220px-Car_ignition_system.svg.png]]

Each coil in the coil pack consists of a primary winding and a secondary winding, which share a common magnetic core. Both coils are connected to the battery. Additionally, the primary is connected to the distributor and the secondary coil is connected to the spark plugs through the cap and rotor within the distributor. The secondary winding has more turns in its coil, resulting in a much higher voltage that runs through it.

[[File:CarDistributor.jpg|250px]] [[File:Ls2_coil_schematic.jpg|250px]]

Initially, the [https://en.wikipedia.org/wiki/Contact_breaker contact breaker] is closed, completing the circuit and allowing current to flow from the battery, through the primary coil and contact breaker and back through the battery. This flow of current creates a [http://www.physicsbook.gatech.edu/Magnetic_field magnetic field] in the primary's core. The distributor shaft is attached to the camshaft lobes, which dictate when the contact breaker is open or closed. If open, without the current flow, there is no magnetic field. Because this connection is dependent on the cams, there is a cyclical repetition of the existence of a magnetic field. The rapid change of this field causes a large change in [http://www.physicsbook.gatech.edu/Magnetic_Flux magnetic flux]. According to [http://www.physicsbook.gatech.edu/Faraday%27s_Law Faraday's Law], this change in magnetic flux will cause a curly electric field which will induce a large voltage that will be crucial to spark plug function.

[[File:magneticfieldIgsyst.jpg|400px]]

Because the primary coil is wrapped around the secondary coil, a varying magnetic field induces an electric current to be run through the secondary coil, which in turn produces a much larger EMF due to the number of loops in the coil. This will take the inputted DC voltage (again, typically 12-24V) and output 15,000V-40,000V AC. That current is fed to the spark plugs, which have a center electrode that is isolated from grounding electrode, grounded through the spark plug casing to the engine, which shares a ground with the coil. The two electrodes have a gap between them that is set typically between .4mm and 1.7mm. A smaller gap requires less voltage from the coil, a larger gap requires more voltage from the coil. In this case, the spark plug's electrodes act as a capacitor with the air in the cylinder being a dielectric insulator. For a spark to occur, the voltage from the coil must be sufficient to cause dielectric breakdown of the air. As the current crosses the electrodes, there is a drastic raise in the temperature upwards of 60,000K, creating a small spark. When this happens, a click from the spark plug can be heard. This spark ignites the air-fuel mixture in the cylinder continuing the crankshaft motion. The distributor cap and rotor determine which cylinder receives a spark to match the firing order.

===Electronic Ignition===

An electronic ignition system, common among modern cars, solves some of the flaws of the mechanical system: wear, oxidation, and contact of breaker points. Angular sensors replace these breaker points and tell the [https://en.wikipedia.org/wiki/Engine_control_unit engine control unit(ECU)].

[[File:ElectronicIgnitionSystem.jpg]]

A common example, Hall effect sensors, relies on magnetic fields to send signals to the ECU. (See [http://www.physicsbook.gatech.edu/Hall_Effect Hall Effect] for more in-depth information on the fundamental principles behind this). Once the magnetic flux density around the sensor exceeds a certain threshold, it generates voltage, triggering a device to send a large amount of current through the coils in the coil pack. This magnetic flux is created by a rotating magnet on the distributor shaft. The impact to the spark plugs themselves is the same.

[[File:Halleffectsensor.gif]] [[File:Mag26.gif]]

===A Mathematical Model===

The primary physics equation used when analyzing spark plugs is Faraday's Law, which states <math>\mathcal{E} = -{{d\Phi_B} \over dt} \ </math>, where <math>\mathcal{E}</math> is the electromotive force(EMF) produced from the time-varying magnetic flux Φ''B''. The flux is given by <math> \int_{\Sigma} \mathbf{B} \cdot d\mathbf{A}. </math>

[[File:Faraday+s+Law+and+Ignition.jpg|500px]]

The basic equation for dielectric breakdown is given as <math>{{V_d}_b}= {{E_d}_sd}</math>

V''db'' represents the dielectric breakdown voltage and E''ds'' represents the dielectric strength of the insulator and d is the distance. The dielectric strength of air is 3x10^6 V/m, so at a gap of 1mm, the required voltage for dielectric breakdown is 30,000V.

That is a good model for the spark outside of an engine at ambient temperature but there are other variables to consider for voltage required inside of the engine because the dielectric strength will change. If it is assumed the spark plugs have no sort of buildup from carbon or oil, the other variables that effect dielectric breakdown voltage are electrical frequency, temperature, the fact that the dielectric material is not just air but a mixture of gasoline and air at a specific ratio, plus the shape, size, and thickness of the electrodes of the spark plug. The temperature inside of the combustion chamber is typically around 1500 degrees Celcius, increased temperature decreases the dielectric strength. Increased electrical frequency decreases the dielectric strength which is why some manufacturers have researched using higher frequency ignition systems. Gasoline's chemical makeup can vary but Benzene, a component of gasoline, has a dielectric strength of 163x10^6 V/m which is much higher than the dielectric strength of air.

===Further Explanation of System===

[https://www.youtube.com/watch?v=__FRCSvEYdE Ignition System Function]
[https://www.youtube.com/watch?v=sFiGsCkAMbk Description of Spark Plug]

==Examples==

http://vicsauto.net/images/anatomy_sparkplug.JPG

Anatomy of a Typical Spark Plug

https://media.boingboing.net/wp-content/uploads/2015/06/skd282544sdc_XS.jpg

Firing Spark Plug

==Connectedness==
Spark Plugs allow gasoline engines to run. The heat from the spark generated by the ignition system causes the gasoline to combust and drive the piston away to turn the crankshaft. This only works if the spark's heat is above the flashpoint of the fuel. Gasoline has a relatively low flashpoint while diesel has a relatively high flashpoint which is why gasoline engines operate at lower pressures with and with spark plugs (spark ignition) and diesels operate at much higher pressures with no spark (compression ignition). Those concepts would apply more so in a course covering thermodynamics. I am a DIY mechanic who works on both gasoline and diesel engines so understanding the physics behind the ignition system of an engine is useful for my tinkering and modifications of the vehicles I work on. A spark ignition system is mostly related to electrical engineering but as it's fundamental concepts are fairly basic in terms of electrical engineering, they are covered in the mechanical engineering curriculum. The stresses, forces and heat generated by combustion are certainly integral concepts of the mechanical engineering curriculum.

==History==
Spark plugs have been around since at least 1859. There are reports that a rudimentary version of the spark plug was originally invented by an African-American man by the name of Edmond Berger in 1839 but he did not patent it. Spark ignition was first used in an early internal combustion engine created by Belgian inventor Étienne Lenoir in 1859. British physicist Sir Oliver Lodge provided many improvements to the design in the 1880s. At the turn of the century, many patents for spark plugs were filed by Nikola Tesla, Robert Bosch, Frederick Richard Simms but Bosch is usually credited with the first commercially viable high-voltage spark plugs (1802) and Albert Champion is credited with expanding its use when he built a spark plug factory in Boston in 1805 and supplied American automobile manufacturers. Sir Oliver Lodge's children started Lodge Plug Company in Britain which allowed the British automobile industry to take off. Similarly, Bosch's spark plugs were largely used by automobile manufacturers in mainland Europe.

Throughout the years, improvements have been made such as adding resistors to the plugs to decrease radio interference, different electrode materials, and the ignition system itself has moved from points and distributors to electronic controllers. Spark plugs have been used in things other than internal combustion engines, such as the second and third stages of the Saturn V rocket.

== See also ==

[http://www.physicsbook.gatech.edu/Magnetic_Field_of_a_Solenoid Magnetic Field of a Solenoid]

[http://www.physicsbook.gatech.edu/Curly_Electric_Fields Curly Electric Fields]

[http://www.physicsbook.gatech.edu/Faraday%27s_Law Faraday's Law]

[http://www.physicsbook.gatech.edu/Inductance Inductance]

[http://www.physicsbook.gatech.edu/Transformers_from_a_physics_standpoint Transformers]

===External links===

[http://www.ngk.com.au/spark-plugs/technical-information/spark-plug-anatomy-construction Spark Plug Anatomy]

==References==

http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/ignition.html

http://auto.howstuffworks.com/spark-plugs.htm

https://www.youtube.com/watch?v=b2udCm7DMzU

http://physics.info/dielectrics/

http://www.engineeringtoolbox.com/liquid-dielectric-constants-d_1263.html

http://www.themotormuseuminminiature.co.uk/inv-jeanjoseph-etienne-lenoir.php

https://www.hemmings.com/magazine/hcc/2006/01/Albert-Champion/1281809.html

http://www.kisouman.com/spark_plug_description-1071.html

http://mechanicstips.blogspot.com/2015/06/how-four-stroke-cycle-engine-works.html

http://www.gsparkplug.com/shop/how-spark-plugs-work/

http://www.mech4study.com/2017/03/magneto-ignition-system-parts-function-working-advantages-and-disadvantages.html

https://www.slideshare.net/jesscar/piston-engines-ignition

http://www.electronics-tutorials.ws/electromagnetism/hall-effect.html

[[Category:Real Life Applications of Electromagnetic Principles]]

File:Faraday+s+Law+and+Ignition.jpg

2017-11-28T23:01:13Z

Gellis9:

Spark Plugs

2017-11-28T23:00:32Z

Gellis9:

Claimed By Christopher Skretkowicz
Claimed By Edward Mauger Spring 2017
'''Claimed By Geraghty Anne Ellis Fall 2017 (Edits)'''

This page chronicles the inner workings and hidden mechanisms involved with spark plug applications, and their integration with automotive ignition systems in the real world.

==Basic Engine Theory==

In order to understand how spark plugs work, there must be some background explanation for the systems that use them. Internal combustion engines are those that rely on the ignition of the air-fuel mixture to create the energy used to power most modern vehicles. [The different types [https://en.wikipedia.org/wiki/Two-stroke_engine two-stroke] and four-stroke. [https://auto.howstuffworks.com/rotary-engine4.htm Rotary engines] use the four-stroke cycle but accomplish combustion much differently. Spark plugs are used in all aforementioned applications for the same purpose. For simplicity, the four-stroke IC engine will be discussed in slightly more detail.

There are four main phases or "strokes" for each combustion chamber of the four-stroke engine: intake, compression, power, and exhaust. Regardless of how many cylinders, all of these engines have a firing order - order of which spark plugs are ignited. This sequential order, rather than all firing at once, allows for the continuous motion of the crankshaft.

[[File:IC_engine.jpg]]

[[File:4-Stroke-Engine-with-airflows.gif]] [[File:enginefiringorder.gif]]

===Intake===

Air is pulled into the engine from the environment by the air intake and stored in the plenum. From the plenum, air enters the intake manifold where fuel injectors will distribute the proper ratio of fuel to the amount of air. Naturally aspirated engines (no turbos, superchargers or anything used to force more air into the engine) typically run at a 14:1 air/fuel ratio. The intake manifold is bolted directly onto the engine so that this mixture can enter the combustion chamber or bore. Intake valves during seal the opening to the chamber on the intake side of the engine; during this phase or "stroke" however, they are opened to allow the air-fuel mixture into the bore. [https://en.wikipedia.org/wiki/Piston Pisons], which travel up and down the bore and connected to the crankshaft (see below), are towards the bottom of the bore during this stroke to allow for the most air to enter the combustion chamber and will reach [https://en.wikipedia.org/wiki/Dead_centre_(engineering)#Reciprocating_engine BDC or bottom dead center].

[[File:Ferrari_air_intake_system.jpg|400px]]

[https://en.wikipedia.org/wiki/Camshaft Camshafts] are used to control when these valves(both intake and exhaust, which will be discussed later) open and close and are directly connected to the [https://en.wikipedia.org/wiki/Crankshaft crankshaft], which in short translate the reciprocating motion of the engine to rotational motion which will eventually be translated through the drivetrain to [https://itstillruns.com/car-move-5104221.html propell the vehicle forward.]

===Compression===

In this stroke, the piston moves to the top of the bore, compressing the air-fuel mixture. Both intake and exhaust valves are shut to not allow for any air to escape. Compressing the mixture enables more energy to be expelled when it is ignited and generates heat, which enables the combustion process to happen more quickly after the mixture is ignited. This process follows the ideal gas law in that as pressure is increased and volume decreased, so must the temperature increase.

===Power===

During the power stroke, just before the piston reaches TDC, or top dead center (the very top of the bore), the spark plug ignites creating a combustion reaction. This explosion forces the piston downwards, and so the crankshaft continues to rotate.

===Exhaust===

With the piston moving back up the bore, what remains of the air-fuel mixture after combustion is no longer needed. The camshaft allows the exhaust valve to open and these exhaust gases are pushed out of the combustion chamber through the exhaust manifold, into the [https://en.wikipedia.org/wiki/Catalytic_converter catalytic converter] to lessen the amount of pollution produced, through the [https://en.wikipedia.org/wiki/Muffler muffler] to lessen the noise emitted, and out the tailpipe into the environment.
Back inside the engine, the exhaust valve closes and the intake stroke begins again.

[[File:Exhaust_system.jpg]]

==The Main Idea==

Spark plugs are essentially what their namesake says they are: plugs that screw into the cylinders of an engine and produce sparks that ignite fuel in combustion engines during the power stroke. Spark plugs take advantage of Faraday's Law and induction to create large spikes of voltage, typically around 40,000 V, across an electrode gap that would otherwise be impossible to achieve with a regular 12 volt car battery. Their two main functions are to produce spark and to remove heat from the combustion chamber.

[[File:Spark_plug.gif]]

===Mechanical Ignition===

Automotive ignition systems are either mechanically or electrically timed and powered by a 12V battery. A mechanically timed ignition system contains a distributor, coil pack, spark plugs, and wires.

[[File:220px-Car_ignition_system.svg.png]]

Each coil in the coil pack consists of a primary winding and a secondary winding, which share a common magnetic core. Both coils are connected to the battery. Additionally, the primary is connected to the distributor and the secondary coil is connected to the spark plugs through the cap and rotor within the distributor. The secondary winding has more turns in its coil, resulting in a much higher voltage that runs through it.

[[File:CarDistributor.jpg|250px]] [[File:Ls2_coil_schematic.jpg|250px]]

Initially, the [https://en.wikipedia.org/wiki/Contact_breaker contact breaker] is closed, completing the circuit and allowing current to flow from the battery, through the primary coil and contact breaker and back through the battery. This flow of current creates a [http://www.physicsbook.gatech.edu/Magnetic_field magnetic field] in the primary's core. The distributor shaft is attached to the camshaft lobes, which dictate when the contact breaker is open or closed. If open, without the current flow, there is no magnetic field. Because this connection is dependent on the cams, there is a cyclical repetition of the existence of a magnetic field. The rapid change of this field causes a large change in [http://www.physicsbook.gatech.edu/Magnetic_Flux magnetic flux]. According to [http://www.physicsbook.gatech.edu/Faraday%27s_Law Faraday's Law], this change in magnetic flux will cause a curly electric field which will induce a large voltage that will be crucial to spark plug function.

[[File:magneticfieldIgsyst.jpg|400px]]

Because the primary coil is wrapped around the secondary coil, a varying magnetic field induces an electric current to be run through the secondary coil, which in turn produces a much larger EMF due to the number of loops in the coil. This will take the inputted DC voltage (again, typically 12-24V) and output 15,000V-40,000V AC. That current is fed to the spark plugs, which have a center electrode that is isolated from grounding electrode, grounded through the spark plug casing to the engine, which shares a ground with the coil. The two electrodes have a gap between them that is set typically between .4mm and 1.7mm. A smaller gap requires less voltage from the coil, a larger gap requires more voltage from the coil. In this case, the spark plug's electrodes act as a capacitor with the air in the cylinder being a dielectric insulator. For a spark to occur, the voltage from the coil must be sufficient to cause dielectric breakdown of the air. As the current crosses the electrodes, there is a drastic raise in the temperature upwards of 60,000K, creating a small spark. When this happens, a click from the spark plug can be heard. This spark ignites the air-fuel mixture in the cylinder continuing the crankshaft motion. The distributor cap and rotor determine which cylinder receives a spark to match the firing order.

===Electronic Ignition===

An electronic ignition system, common among modern cars, solves some of the flaws of the mechanical system: wear, oxidation, and contact of breaker points. Angular sensors replace these breaker points and tell the [https://en.wikipedia.org/wiki/Engine_control_unit engine control unit(ECU)].

[[File:ElectronicIgnitionSystem.jpg]]

A common example, Hall effect sensors, relies on magnetic fields to send signals to the ECU. (See [http://www.physicsbook.gatech.edu/Hall_Effect Hall Effect] for more in-depth information on the fundamental principles behind this). Once the magnetic flux density around the sensor exceeds a certain threshold, it generates voltage, triggering a device to send a large amount of current through the coils in the coil pack. This magnetic flux is created by a rotating magnet on the distributor shaft. The impact to the spark plugs themselves is the same.

[[File:Halleffectsensor.gif]] [[File:Mag26.gif]]

===A Mathematical Model===

The primary physics equation used when analyzing spark plugs is Faraday's Law, which states <math>\mathcal{E} = -{{d\Phi_B} \over dt} \ </math>, where <math>\mathcal{E}</math> is the electromotive force(EMF) produced from the time-varying magnetic flux Φ''B''. The flux is given by <math> \int_{\Sigma} \mathbf{B} \cdot d\mathbf{A}. </math>

[[File:Faraday+s+Law+and+Ignition.jpg]]

The basic equation for dielectric breakdown is given as <math>{{V_d}_b}= {{E_d}_sd}</math>

V''db'' represents the dielectric breakdown voltage and E''ds'' represents the dielectric strength of the insulator and d is the distance. The dielectric strength of air is 3x10^6 V/m, so at a gap of 1mm, the required voltage for dielectric breakdown is 30,000V.

That is a good model for the spark outside of an engine at ambient temperature but there are other variables to consider for voltage required inside of the engine because the dielectric strength will change. If it is assumed the spark plugs have no sort of buildup from carbon or oil, the other variables that effect dielectric breakdown voltage are electrical frequency, temperature, the fact that the dielectric material is not just air but a mixture of gasoline and air at a specific ratio, plus the shape, size, and thickness of the electrodes of the spark plug. The temperature inside of the combustion chamber is typically around 1500 degrees Celcius, increased temperature decreases the dielectric strength. Increased electrical frequency decreases the dielectric strength which is why some manufacturers have researched using higher frequency ignition systems. Gasoline's chemical makeup can vary but Benzene, a component of gasoline, has a dielectric strength of 163x10^6 V/m which is much higher than the dielectric strength of air.

===Further Explanation of System===

[https://www.youtube.com/watch?v=__FRCSvEYdE Ignition System Function]
[https://www.youtube.com/watch?v=sFiGsCkAMbk Description of Spark Plug]

==Examples==

http://vicsauto.net/images/anatomy_sparkplug.JPG

Anatomy of a Typical Spark Plug

https://media.boingboing.net/wp-content/uploads/2015/06/skd282544sdc_XS.jpg

Firing Spark Plug

==Connectedness==
Spark Plugs allow gasoline engines to run. The heat from the spark generated by the ignition system causes the gasoline to combust and drive the piston away to turn the crankshaft. This only works if the spark's heat is above the flashpoint of the fuel. Gasoline has a relatively low flashpoint while diesel has a relatively high flashpoint which is why gasoline engines operate at lower pressures with and with spark plugs (spark ignition) and diesels operate at much higher pressures with no spark (compression ignition). Those concepts would apply more so in a course covering thermodynamics. I am a DIY mechanic who works on both gasoline and diesel engines so understanding the physics behind the ignition system of an engine is useful for my tinkering and modifications of the vehicles I work on. A spark ignition system is mostly related to electrical engineering but as it's fundamental concepts are fairly basic in terms of electrical engineering, they are covered in the mechanical engineering curriculum. The stresses, forces and heat generated by combustion are certainly integral concepts of the mechanical engineering curriculum.

==History==
Spark plugs have been around since at least 1859. There are reports that a rudimentary version of the spark plug was originally invented by an African-American man by the name of Edmond Berger in 1839 but he did not patent it. Spark ignition was first used in an early internal combustion engine created by Belgian inventor Étienne Lenoir in 1859. British physicist Sir Oliver Lodge provided many improvements to the design in the 1880s. At the turn of the century, many patents for spark plugs were filed by Nikola Tesla, Robert Bosch, Frederick Richard Simms but Bosch is usually credited with the first commercially viable high-voltage spark plugs (1802) and Albert Champion is credited with expanding its use when he built a spark plug factory in Boston in 1805 and supplied American automobile manufacturers. Sir Oliver Lodge's children started Lodge Plug Company in Britain which allowed the British automobile industry to take off. Similarly, Bosch's spark plugs were largely used by automobile manufacturers in mainland Europe.

Throughout the years, improvements have been made such as adding resistors to the plugs to decrease radio interference, different electrode materials, and the ignition system itself has moved from points and distributors to electronic controllers. Spark plugs have been used in things other than internal combustion engines, such as the second and third stages of the Saturn V rocket.

== See also ==

[http://www.physicsbook.gatech.edu/Magnetic_Field_of_a_Solenoid Magnetic Field of a Solenoid]

[http://www.physicsbook.gatech.edu/Curly_Electric_Fields Curly Electric Fields]

[http://www.physicsbook.gatech.edu/Faraday%27s_Law Faraday's Law]

[http://www.physicsbook.gatech.edu/Inductance Inductance]

[http://www.physicsbook.gatech.edu/Transformers_from_a_physics_standpoint Transformers]

===External links===

[http://www.ngk.com.au/spark-plugs/technical-information/spark-plug-anatomy-construction Spark Plug Anatomy]

==References==

http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/ignition.html

http://auto.howstuffworks.com/spark-plugs.htm

https://www.youtube.com/watch?v=b2udCm7DMzU

http://physics.info/dielectrics/

http://www.engineeringtoolbox.com/liquid-dielectric-constants-d_1263.html

http://www.themotormuseuminminiature.co.uk/inv-jeanjoseph-etienne-lenoir.php

https://www.hemmings.com/magazine/hcc/2006/01/Albert-Champion/1281809.html

http://www.kisouman.com/spark_plug_description-1071.html

http://mechanicstips.blogspot.com/2015/06/how-four-stroke-cycle-engine-works.html

http://www.gsparkplug.com/shop/how-spark-plugs-work/

http://www.mech4study.com/2017/03/magneto-ignition-system-parts-function-working-advantages-and-disadvantages.html

https://www.slideshare.net/jesscar/piston-engines-ignition

http://www.electronics-tutorials.ws/electromagnetism/hall-effect.html

[[Category:Real Life Applications of Electromagnetic Principles]]

Spark Plugs

2017-11-28T22:55:33Z

Gellis9:

Claimed By Christopher Skretkowicz
Claimed By Edward Mauger Spring 2017
'''Claimed By Geraghty Anne Ellis Fall 2017 (Edits)'''

This page chronicles the inner workings and hidden mechanisms involved with spark plug applications, and their integration with automotive ignition systems in the real world.

==Basic Engine Theory==

In order to understand how spark plugs work, there must be some background explanation for the systems that use them. Internal combustion engines are those that rely on the ignition of the air-fuel mixture to create the energy used to power most modern vehicles. [The different types [https://en.wikipedia.org/wiki/Two-stroke_engine two-stroke] and four-stroke. [https://auto.howstuffworks.com/rotary-engine4.htm Rotary engines] use the four-stroke cycle but accomplish combustion much differently. Spark plugs are used in all aforementioned applications for the same purpose. For simplicity, the four-stroke IC engine will be discussed in slightly more detail.

There are four main phases or "strokes" for each combustion chamber of the four-stroke engine: intake, compression, power, and exhaust. Regardless of how many cylinders, all of these engines have a firing order - order of which spark plugs are ignited. This sequential order, rather than all firing at once, allows for the continuous motion of the crankshaft.

[[File:IC_engine.jpg]]

[[File:4-Stroke-Engine-with-airflows.gif]] [[File:enginefiringorder.gif]]

===Intake===

Air is pulled into the engine from the environment by the air intake and stored in the plenum. From the plenum, air enters the intake manifold where fuel injectors will distribute the proper ratio of fuel to the amount of air. Naturally aspirated engines (no turbos, superchargers or anything used to force more air into the engine) typically run at a 14:1 air/fuel ratio. The intake manifold is bolted directly onto the engine so that this mixture can enter the combustion chamber or bore. Intake valves during seal the opening to the chamber on the intake side of the engine; during this phase or "stroke" however, they are opened to allow the air-fuel mixture into the bore. [https://en.wikipedia.org/wiki/Piston Pisons], which travel up and down the bore and connected to the crankshaft (see below), are towards the bottom of the bore during this stroke to allow for the most air to enter the combustion chamber and will reach [https://en.wikipedia.org/wiki/Dead_centre_(engineering)#Reciprocating_engine BDC or bottom dead center].

[[File:Ferrari_air_intake_system.jpg|400px]]

[https://en.wikipedia.org/wiki/Camshaft Camshafts] are used to control when these valves(both intake and exhaust, which will be discussed later) open and close and are directly connected to the [https://en.wikipedia.org/wiki/Crankshaft crankshaft], which in short translate the reciprocating motion of the engine to rotational motion which will eventually be translated through the drivetrain to [https://itstillruns.com/car-move-5104221.html propell the vehicle forward.]

===Compression===

In this stroke, the piston moves to the top of the bore, compressing the air-fuel mixture. Both intake and exhaust valves are shut to not allow for any air to escape. Compressing the mixture enables more energy to be expelled when it is ignited and generates heat, which enables the combustion process to happen more quickly after the mixture is ignited. This process follows the ideal gas law in that as pressure is increased and volume decreased, so must the temperature increase.

===Power===

During the power stroke, just before the piston reaches TDC, or top dead center (the very top of the bore), the spark plug ignites creating a combustion reaction. This explosion forces the piston downwards, and so the crankshaft continues to rotate.

===Exhaust===

With the piston moving back up the bore, what remains of the air-fuel mixture after combustion is no longer needed. The camshaft allows the exhaust valve to open and these exhaust gases are pushed out of the combustion chamber through the exhaust manifold, into the [https://en.wikipedia.org/wiki/Catalytic_converter catalytic converter] to lessen the amount of pollution produced, through the [https://en.wikipedia.org/wiki/Muffler muffler] to lessen the noise emitted, and out the tailpipe into the environment.
Back inside the engine, the exhaust valve closes and the intake stroke begins again.

[[File:Exhaust_system.jpg]]

==The Main Idea==

Spark plugs are essentially what their namesake says they are: plugs that screw into the cylinders of an engine and produce sparks that ignite fuel in combustion engines during the power stroke. Spark plugs take advantage of Faraday's Law and induction to create large spikes of voltage, typically around 40,000 V, across an electrode gap that would otherwise be impossible to achieve with a regular 12 volt car battery. Their two main functions are to produce spark and to remove heat from the combustion chamber.

[[File:Spark_plug.gif]]

===Mechanical Ignition===

Automotive ignition systems are either mechanically or electrically timed and powered by a 12V battery. A mechanically timed ignition system contains a distributor, coil pack, spark plugs, and wires.

[[File:220px-Car_ignition_system.svg.png]]

Each coil in the coil pack consists of a primary winding and a secondary winding, which share a common magnetic core. Both coils are connected to the battery. Additionally, the primary is connected to the distributor and the secondary coil is connected to the spark plugs through the cap and rotor within the distributor. The secondary winding has more turns in its coil, resulting in a much higher voltage that runs through it.

[[File:CarDistributor.jpg|250px]] [[File:Ls2_coil_schematic.jpg|250px]]

Initially, the [https://en.wikipedia.org/wiki/Contact_breaker contact breaker] is closed, completing the circuit and allowing current to flow from the battery, through the primary coil and contact breaker and back through the battery. This flow of current creates a [http://www.physicsbook.gatech.edu/Magnetic_field magnetic field] in the primary's core. The distributor shaft is attached to the camshaft lobes, which dictate when the contact breaker is open or closed. If open, without the current flow, there is no magnetic field. Because this connection is dependent on the cams, there is a cyclical repetition of the existence of a magnetic field. The rapid change of this field causes a large change in [http://www.physicsbook.gatech.edu/Magnetic_Flux magnetic flux]. According to [http://www.physicsbook.gatech.edu/Faraday%27s_Law Faraday's Law], this change in magnetic flux will cause a curly electric field which will induce a large voltage that will be crucial to spark plug function.

[[File:magneticfieldIgsyst.jpg|400px]]

Because the primary coil is wrapped around the secondary coil, a varying magnetic field induces an electric current to be run through the secondary coil, which in turn produces a much larger EMF due to the number of loops in the coil. This will take the inputted DC voltage (again, typically 12-24V) and output 15,000V-40,000V AC. That current is fed to the spark plugs, which have a center electrode that is isolated from grounding electrode, grounded through the spark plug casing to the engine, which shares a ground with the coil. The two electrodes have a gap between them that is set typically between .4mm and 1.7mm. A smaller gap requires less voltage from the coil, a larger gap requires more voltage from the coil. In this case, the spark plug's electrodes act as a capacitor with the air in the cylinder being a dielectric insulator. For a spark to occur, the voltage from the coil must be sufficient to cause dielectric breakdown of the air. As the current crosses the electrodes, there is a drastic raise in the temperature upwards of 60,000K, creating a small spark. When this happens, a click from the spark plug can be heard. This spark ignites the air-fuel mixture in the cylinder continuing the crankshaft motion. The distributor cap and rotor determine which cylinder receives a spark to match the firing order.

===Electronic Ignition===

An electronic ignition system, common among modern cars, solves some of the flaws of the mechanical system: wear, oxidation, and contact of breaker points. Angular sensors replace these breaker points and tell the [https://en.wikipedia.org/wiki/Engine_control_unit engine control unit(ECU)].

[[File:ElectronicIgnitionSystem.jpg]]

A common example, Hall effect sensors, relies on magnetic fields to send signals to the ECU. (See [http://www.physicsbook.gatech.edu/Hall_Effect Hall Effect] for more in-depth information on the fundamental principles behind this). Once the magnetic flux density around the sensor exceeds a certain threshold, it generates voltage, triggering a device to send a large amount of current through the coils in the coil pack. This magnetic flux is created by a rotating magnet on the distributor shaft. The impact to the spark plugs themselves is the same.

[[File:Halleffectsensor.gif]] [[File:Mag26.gif]]

===A Mathematical Model===

The primary physics equation used when analyzing spark plugs is Faraday's Law, which states <math>\mathcal{E} = -{{d\Phi_B} \over dt} \ </math>, where <math>\mathcal{E}</math> is the electromotive force(EMF) produced from the time-varying magnetic flux Φ''B''. The flux is given by <math> \int_{\Sigma} \mathbf{B} \cdot d\mathbf{A}. </math>

The basic equation for dielectric breakdown is given as <math>{{V_d}_b}= {{E_d}_sd}</math>

V''db'' represents the dielectric breakdown voltage and E''ds'' represents the dielectric strength of the insulator and d is the distance. The dielectric strength of air is 3x10^6 V/m, so at a gap of 1mm, the required voltage for dielectric breakdown is 30,000V.

That is a good model for the spark outside of an engine at ambient temperature but there are other variables to consider for voltage required inside of the engine because the dielectric strength will change. If it is assumed the spark plugs have no sort of buildup from carbon or oil, the other variables that effect dielectric breakdown voltage are electrical frequency, temperature, the fact that the dielectric material is not just air but a mixture of gasoline and air at a specific ratio, plus the shape, size, and thickness of the electrodes of the spark plug. The temperature inside of the combustion chamber is typically around 1500 degrees Celcius, increased temperature decreases the dielectric strength. Increased electrical frequency decreases the dielectric strength which is why some manufacturers have researched using higher frequency ignition systems. Gasoline's chemical makeup can vary but Benzene, a component of gasoline, has a dielectric strength of 163x10^6 V/m which is much higher than the dielectric strength of air.

===Further Explanation of System===

[https://www.youtube.com/watch?v=__FRCSvEYdE Ignition System Function]
[https://www.youtube.com/watch?v=sFiGsCkAMbk Description of Spark Plug]

==Examples==

http://vicsauto.net/images/anatomy_sparkplug.JPG

Anatomy of a Typical Spark Plug

https://media.boingboing.net/wp-content/uploads/2015/06/skd282544sdc_XS.jpg

Firing Spark Plug

==Connectedness==
Spark Plugs allow gasoline engines to run. The heat from the spark generated by the ignition system causes the gasoline to combust and drive the piston away to turn the crankshaft. This only works if the spark's heat is above the flashpoint of the fuel. Gasoline has a relatively low flashpoint while diesel has a relatively high flashpoint which is why gasoline engines operate at lower pressures with and with spark plugs (spark ignition) and diesels operate at much higher pressures with no spark (compression ignition). Those concepts would apply more so in a course covering thermodynamics. I am a DIY mechanic who works on both gasoline and diesel engines so understanding the physics behind the ignition system of an engine is useful for my tinkering and modifications of the vehicles I work on. A spark ignition system is mostly related to electrical engineering but as it's fundamental concepts are fairly basic in terms of electrical engineering, they are covered in the mechanical engineering curriculum. The stresses, forces and heat generated by combustion are certainly integral concepts of the mechanical engineering curriculum.

==History==
Spark plugs have been around since at least 1859. There are reports that a rudimentary version of the spark plug was originally invented by an African-American man by the name of Edmond Berger in 1839 but he did not patent it. Spark ignition was first used in an early internal combustion engine created by Belgian inventor Étienne Lenoir in 1859. British physicist Sir Oliver Lodge provided many improvements to the design in the 1880s. At the turn of the century, many patents for spark plugs were filed by Nikola Tesla, Robert Bosch, Frederick Richard Simms but Bosch is usually credited with the first commercially viable high-voltage spark plugs (1802) and Albert Champion is credited with expanding its use when he built a spark plug factory in Boston in 1805 and supplied American automobile manufacturers. Sir Oliver Lodge's children started Lodge Plug Company in Britain which allowed the British automobile industry to take off. Similarly, Bosch's spark plugs were largely used by automobile manufacturers in mainland Europe.

Throughout the years, improvements have been made such as adding resistors to the plugs to decrease radio interference, different electrode materials, and the ignition system itself has moved from points and distributors to electronic controllers. Spark plugs have been used in things other than internal combustion engines, such as the second and third stages of the Saturn V rocket.

== See also ==

[http://www.physicsbook.gatech.edu/Magnetic_Field_of_a_Solenoid Magnetic Field of a Solenoid]

[http://www.physicsbook.gatech.edu/Curly_Electric_Fields Curly Electric Fields]

[http://www.physicsbook.gatech.edu/Faraday%27s_Law Faraday's Law]

[http://www.physicsbook.gatech.edu/Inductance Inductance]

[http://www.physicsbook.gatech.edu/Transformers_from_a_physics_standpoint Transformers]

===External links===

[http://www.ngk.com.au/spark-plugs/technical-information/spark-plug-anatomy-construction Spark Plug Anatomy]

==References==

http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/ignition.html

http://auto.howstuffworks.com/spark-plugs.htm

https://www.youtube.com/watch?v=b2udCm7DMzU

http://physics.info/dielectrics/

http://www.engineeringtoolbox.com/liquid-dielectric-constants-d_1263.html

http://www.themotormuseuminminiature.co.uk/inv-jeanjoseph-etienne-lenoir.php

https://www.hemmings.com/magazine/hcc/2006/01/Albert-Champion/1281809.html

http://www.kisouman.com/spark_plug_description-1071.html

http://mechanicstips.blogspot.com/2015/06/how-four-stroke-cycle-engine-works.html

http://www.gsparkplug.com/shop/how-spark-plugs-work/

http://www.mech4study.com/2017/03/magneto-ignition-system-parts-function-working-advantages-and-disadvantages.html

https://www.slideshare.net/jesscar/piston-engines-ignition

http://www.electronics-tutorials.ws/electromagnetism/hall-effect.html

[[Category:Real Life Applications of Electromagnetic Principles]]

Spark Plugs

2017-11-28T22:46:53Z

Gellis9:

Claimed By Christopher Skretkowicz
Claimed By Edward Mauger Spring 2017
'''Claimed By Geraghty Anne Ellis Fall 2017 (Edits)'''

This page chronicles the inner workings and hidden mechanisms involved with spark plug applications, and their integration with automotive ignition systems in the real world.

==Basic Engine Theory==

In order to understand how spark plugs work, there must be some background explanation for the systems that use them. Internal combustion engines are those that rely on the ignition of the air-fuel mixture to create the energy used to power most modern vehicles. [The different types [https://en.wikipedia.org/wiki/Two-stroke_engine two-stroke] and four-stroke. [https://auto.howstuffworks.com/rotary-engine4.htm Rotary engines] use the four-stroke cycle but accomplish combustion much differently. Spark plugs are used in all aforementioned applications for the same purpose. For simplicity, the four-stroke IC engine will be discussed in slightly more detail.

There are four main phases or "strokes" for each combustion chamber of the four-stroke engine: intake, compression, power, and exhaust. Regardless of how many cylinders, all of these engines have a firing order - order of which spark plugs are ignited. This sequential order, rather than all firing at once, allows for the continuous motion of the crankshaft.

[[File:IC_engine.jpg]]

[[File:4-Stroke-Engine-with-airflows.gif]] [[File:enginefiringorder.gif]]

===Intake===

Air is pulled into the engine from the environment by the air intake and stored in the plenum. From the plenum, air enters the intake manifold where fuel injectors will distribute the proper ratio of fuel to the amount of air. Naturally aspirated engines (no turbos, superchargers or anything used to force more air into the engine) typically run at a 14:1 air/fuel ratio. The intake manifold is bolted directly onto the engine so that this mixture can enter the combustion chamber or bore. Intake valves during seal the opening to the chamber on the intake side of the engine; during this phase or "stroke" however, they are opened to allow the air-fuel mixture into the bore. [https://en.wikipedia.org/wiki/Piston Pisons], which travel up and down the bore and connected to the crankshaft (see below), are towards the bottom of the bore during this stroke to allow for the most air to enter the combustion chamber and will reach [https://en.wikipedia.org/wiki/Dead_centre_(engineering)#Reciprocating_engine BDC or bottom dead center].

[[File:Ferrari_air_intake_system.jpg|400px]]

[https://en.wikipedia.org/wiki/Camshaft Camshafts] are used to control when these valves(both intake and exhaust, which will be discussed later) open and close and are directly connected to the [https://en.wikipedia.org/wiki/Crankshaft crankshaft], which in short translate the reciprocating motion of the engine to rotational motion which will eventually be translated through the drivetrain to [https://itstillruns.com/car-move-5104221.html propell the vehicle forward.]

===Compression===

In this stroke, the piston moves to the top of the bore, compressing the air-fuel mixture. Both intake and exhaust valves are shut to not allow for any air to escape. Compressing the mixture enables more energy to be expelled when it is ignited and generates heat, which enables the combustion process to happen more quickly after the mixture is ignited. This process follows the ideal gas law in that as pressure is increased and volume decreased, so must the temperature increase.

===Power===

During the power stroke, just before the piston reaches TDC, or top dead center (the very top of the bore), the spark plug ignites creating a combustion reaction. This explosion forces the piston downwards, and so the crankshaft continues to rotate.

===Exhaust===

With the piston moving back up the bore, what remains of the air-fuel mixture after combustion is no longer needed. The camshaft allows the exhaust valve to open and these exhaust gases are pushed out of the combustion chamber through the exhaust manifold, into the [https://en.wikipedia.org/wiki/Catalytic_converter catalytic converter] to lessen the amount of pollution produced, through the [https://en.wikipedia.org/wiki/Muffler muffler] to lessen the noise emitted, and out the tailpipe into the environment.
Back inside the engine, the exhaust valve closes and the intake stroke begins again.

[[File:Exhaust_system.jpg]]

==The Main Idea==

Spark plugs are essentially what their namesake says they are: plugs that screw into the cylinders of an engine and produce sparks that ignite fuel in combustion engines during the power stroke. Spark plugs take advantage of Faraday's Law and induction to create large spikes of voltage, typically around 40,000 V, across an electrode gap that would otherwise be impossible to achieve with a regular 12 volt car battery. Their two main functions are to produce spark and to remove heat from the combustion chamber.

===Mechanical Ignition===

Automotive ignition systems are either mechanically or electrically timed and powered by a 12V battery. A mechanically timed ignition system contains a distributor, coil pack, spark plugs, and wires.

[[File:220px-Car_ignition_system.svg.png]]

Each coil in the coil pack consists of a primary winding and a secondary winding, which share a common magnetic core. Both coils are connected to the battery. Additionally, the primary is connected to the distributor and the secondary coil is connected to the spark plugs through the cap and rotor within the distributor. The secondary winding has more turns in its coil, resulting in a much higher voltage that runs through it.

[[File:CarDistributor.jpg|250px]] [[File:Ls2_coil_schematic.jpg|250px]]

Initially, the [https://en.wikipedia.org/wiki/Contact_breaker contact breaker] is closed, completing the circuit and allowing current to flow from the battery, through the primary coil and contact breaker and back through the battery. This flow of current creates a [http://www.physicsbook.gatech.edu/Magnetic_field magnetic field] in the primary's core. The distributor shaft is attached to the camshaft lobes, which dictate when the contact breaker is open or closed. If open, without the current flow, there is no magnetic field. Because this connection is dependent on the cams, there is a cyclical repetition of the existence of a magnetic field. The rapid change of this field causes a large change in [http://www.physicsbook.gatech.edu/Magnetic_Flux magnetic flux]. According to [http://www.physicsbook.gatech.edu/Faraday%27s_Law Faraday's Law], this change in magnetic flux will cause a curly electric field which will induce a large voltage that will be crucial to spark plug function.

[[File:magneticfieldIgsyst.jpg|400px]]

Because the primary coil is wrapped around the secondary coil, a varying magnetic field induces an electric current to be run through the secondary coil, which in turn produces a much larger EMF due to the number of loops in the coil. This will take the inputted DC voltage (again, typically 12-24V) and output 15,000V-40,000V AC. That current is fed to the spark plugs, which have a center electrode that is isolated from grounding electrode, grounded through the spark plug casing to the engine, which shares a ground with the coil. The two electrodes have a gap between them that is set typically between .4mm and 1.7mm. A smaller gap requires less voltage from the coil, a larger gap requires more voltage from the coil. In this case, the spark plug's electrodes act as a capacitor with the air in the cylinder being a dielectric insulator. For a spark to occur, the voltage from the coil must be sufficient to cause dielectric breakdown of the air. As the current crosses the electrodes, there is a drastic raise in the temperature upwards of 60,000K, creating a small spark. When this happens, a click from the spark plug can be heard. This spark ignites the air-fuel mixture in the cylinder continuing the crankshaft motion. The distributor cap and rotor determine which cylinder receives a spark to match the firing order.

===Electronic Ignition===

An electronic ignition system, common among modern cars, solves some of the flaws of the mechanical system: wear, oxidation, and contact of breaker points. Angular sensors replace these breaker points and tell the [https://en.wikipedia.org/wiki/Engine_control_unit engine control unit(ECU)].

[[File:ElectronicIgnitionSystem.jpg]]

A common example, Hall effect sensors, relies on magnetic fields to send signals to the ECU. (See [http://www.physicsbook.gatech.edu/Hall_Effect Hall Effect] for more in-depth information on the fundamental principles behind this). Once the magnetic flux density around the sensor exceeds a certain threshold, it generates voltage, triggering a device to send a large amount of current through the coils in the coil pack. This magnetic flux is created by a rotating magnet on the distributor shaft. The impact to the spark plugs themselves is the same.

[[File:Halleffectsensor.gif]] [[File:Mag26.gif]]

===A Mathematical Model===

The primary physics equation used when analyzing spark plugs is Faraday's Law, which states <math>\mathcal{E} = -{{d\Phi_B} \over dt} \ </math>, where <math>\mathcal{E}</math> is the electromotive force(EMF) produced from the time-varying magnetic flux Φ''B''. The flux is given by <math> \int_{\Sigma} \mathbf{B} \cdot d\mathbf{A}. </math>

The basic equation for dielectric breakdown is given as <math>{{V_d}_b}= {{E_d}_sd}</math>

V''db'' represents the dielectric breakdown voltage and E''ds'' represents the dielectric strength of the insulator and d is the distance. The dielectric strength of air is 3x10^6 V/m, so at a gap of 1mm, the required voltage for dielectric breakdown is 30,000V.

That is a good model for the spark outside of an engine at ambient temperature but there are other variables to consider for voltage required inside of the engine because the dielectric strength will change. If it is assumed the spark plugs have no sort of buildup from carbon or oil, the other variables that effect dielectric breakdown voltage are electrical frequency, temperature, the fact that the dielectric material is not just air but a mixture of gasoline and air at a specific ratio, plus the shape, size, and thickness of the electrodes of the spark plug. The temperature inside of the combustion chamber is typically around 1500 degrees Celcius, increased temperature decreases the dielectric strength. Increased electrical frequency decreases the dielectric strength which is why some manufacturers have researched using higher frequency ignition systems. Gasoline's chemical makeup can vary but Benzene, a component of gasoline, has a dielectric strength of 163x10^6 V/m which is much higher than the dielectric strength of air.

===Explanation of System===
[[File:Spark_plug.gif]]

[https://www.youtube.com/watch?v=__FRCSvEYdE Ignition System Function]
[https://www.youtube.com/watch?v=sFiGsCkAMbk Description of Spark Plug]

==Examples==

http://vicsauto.net/images/anatomy_sparkplug.JPG

Anatomy of a Typical Spark Plug

https://media.boingboing.net/wp-content/uploads/2015/06/skd282544sdc_XS.jpg

Firing Spark Plug

==Connectedness==
Spark Plugs allow gasoline engines to run. The heat from the spark generated by the ignition system causes the gasoline to combust and drive the piston away to turn the crankshaft. This only works if the spark's heat is above the flashpoint of the fuel. Gasoline has a relatively low flashpoint while diesel has a relatively high flashpoint which is why gasoline engines operate at lower pressures with and with spark plugs (spark ignition) and diesels operate at much higher pressures with no spark (compression ignition). Those concepts would apply more so in a course covering thermodynamics. I am a DIY mechanic who works on both gasoline and diesel engines so understanding the physics behind the ignition system of an engine is useful for my tinkering and modifications of the vehicles I work on. A spark ignition system is mostly related to electrical engineering but as it's fundamental concepts are fairly basic in terms of electrical engineering, they are covered in the mechanical engineering curriculum. The stresses, forces and heat generated by combustion are certainly integral concepts of the mechanical engineering curriculum.

==History==
Spark plugs have been around since at least 1859. There are reports that a rudimentary version of the spark plug was originally invented by an African-American man by the name of Edmond Berger in 1839 but he did not patent it. Spark ignition was first used in an early internal combustion engine created by Belgian inventor Étienne Lenoir in 1859. British physicist Sir Oliver Lodge provided many improvements to the design in the 1880s. At the turn of the century, many patents for spark plugs were filed by Nikola Tesla, Robert Bosch, Frederick Richard Simms but Bosch is usually credited with the first commercially viable high-voltage spark plugs (1802) and Albert Champion is credited with expanding its use when he built a spark plug factory in Boston in 1805 and supplied American automobile manufacturers. Sir Oliver Lodge's children started Lodge Plug Company in Britain which allowed the British automobile industry to take off. Similarly, Bosch's spark plugs were largely used by automobile manufacturers in mainland Europe.

Throughout the years, improvements have been made such as adding resistors to the plugs to decrease radio interference, different electrode materials, and the ignition system itself has moved from points and distributors to electronic controllers. Spark plugs have been used in things other than internal combustion engines, such as the second and third stages of the Saturn V rocket.

== See also ==

[http://www.physicsbook.gatech.edu/Magnetic_Field_of_a_Solenoid Magnetic Field of a Solenoid]

[http://www.physicsbook.gatech.edu/Curly_Electric_Fields Curly Electric Fields]

[http://www.physicsbook.gatech.edu/Faraday%27s_Law Faraday's Law]

[http://www.physicsbook.gatech.edu/Inductance Inductance]

[http://www.physicsbook.gatech.edu/Transformers_from_a_physics_standpoint Transformers]

===External links===

[http://www.ngk.com.au/spark-plugs/technical-information/spark-plug-anatomy-construction Spark Plug Anatomy]

==References==

http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/ignition.html

http://auto.howstuffworks.com/spark-plugs.htm

https://www.youtube.com/watch?v=b2udCm7DMzU

http://physics.info/dielectrics/

http://www.engineeringtoolbox.com/liquid-dielectric-constants-d_1263.html

http://www.themotormuseuminminiature.co.uk/inv-jeanjoseph-etienne-lenoir.php

https://www.hemmings.com/magazine/hcc/2006/01/Albert-Champion/1281809.html

http://www.kisouman.com/spark_plug_description-1071.html

http://mechanicstips.blogspot.com/2015/06/how-four-stroke-cycle-engine-works.html

http://www.gsparkplug.com/shop/how-spark-plugs-work/

http://www.mech4study.com/2017/03/magneto-ignition-system-parts-function-working-advantages-and-disadvantages.html

https://www.slideshare.net/jesscar/piston-engines-ignition

http://www.electronics-tutorials.ws/electromagnetism/hall-effect.html

[[Category:Real Life Applications of Electromagnetic Principles]]

Spark Plugs

2017-11-28T22:37:00Z

Gellis9:

Claimed By Christopher Skretkowicz
Claimed By Edward Mauger Spring 2017
'''Claimed By Geraghty Anne Ellis Fall 2017 (Edits)'''

This page chronicles the inner workings and hidden mechanisms involved with spark plug applications, and their integration with automotive ignition systems in the real world.

==Basic Engine Theory==

In order to understand how spark plugs work, there must be some background explanation for the systems that use them. Internal combustion engines are those that rely on the ignition of the air-fuel mixture to create the energy used to power most modern vehicles. [The different types [https://en.wikipedia.org/wiki/Two-stroke_engine two-stroke] and four-stroke. [https://auto.howstuffworks.com/rotary-engine4.htm Rotary engines] use the four-stroke cycle but accomplish combustion much differently. Spark plugs are used in all aforementioned applications for the same purpose. For simplicity, the four-stroke IC engine will be discussed in slightly more detail.

There are four main phases or "strokes" for each combustion chamber of the four-stroke engine: intake, compression, power, and exhaust. Regardless of how many cylinders, all of these engines have a firing order - order of which spark plugs are ignited. This sequential order, rather than all firing at once, allows for the continuous motion of the crankshaft.

[[File:IC_engine.jpg]]

[[File:4-Stroke-Engine-with-airflows.gif]] [[File:enginefiringorder.gif]]

===Intake===

Air is pulled into the engine from the environment by the air intake and stored in the plenum. From the plenum, air enters the intake manifold where fuel injectors will distribute the proper ratio of fuel to the amount of air. Naturally aspirated engines (no turbos, superchargers or anything used to force more air into the engine) typically run at a 14:1 air/fuel ratio. The intake manifold is bolted directly onto the engine so that this mixture can enter the combustion chamber or bore. Intake valves during seal the opening to the chamber on the intake side of the engine; during this phase or "stroke" however, they are opened to allow the air-fuel mixture into the bore. [https://en.wikipedia.org/wiki/Piston Pisons], which travel up and down the bore and connected to the crankshaft (see below), are towards the bottom of the bore during this stroke to allow for the most air to enter the combustion chamber and will reach [https://en.wikipedia.org/wiki/Dead_centre_(engineering)#Reciprocating_engine BDC or bottom dead center].

[[File:Ferrari_air_intake_system.jpg|400px]]

[https://en.wikipedia.org/wiki/Camshaft Camshafts] are used to control when these valves(both intake and exhaust, which will be discussed later) open and close and are directly connected to the [https://en.wikipedia.org/wiki/Crankshaft crankshaft], which in short translate the reciprocating motion of the engine to rotational motion which will eventually be translated through the drivetrain to [https://itstillruns.com/car-move-5104221.html propell the vehicle forward.]

===Compression===

In this stroke, the piston moves to the top of the bore, compressing the air-fuel mixture. Both intake and exhaust valves are shut to not allow for any air to escape. Compressing the mixture enables more energy to be expelled when it is ignited and generates heat, which enables the combustion process to happen more quickly after the mixture is ignited. This process follows the ideal gas law in that as pressure is increased and volume decreased, so must the temperature increase.

===Power===

During the power stroke, just before the piston reaches TDC, or top dead center (the very top of the bore), the spark plug ignites creating a combustion reaction. This explosion forces the piston downwards, and so the crankshaft continues to rotate.

===Exhaust===

With the piston moving back up the bore, what remains of the air-fuel mixture after combustion is no longer needed. The camshaft allows the exhaust valve to open and these exhaust gases are pushed out of the combustion chamber through the exhaust manifold, into the [https://en.wikipedia.org/wiki/Catalytic_converter catalytic converter] to lessen the amount of pollution produced, through the [https://en.wikipedia.org/wiki/Muffler muffler] to lessen the noise emitted, and out the tailpipe into the environment.
Back inside the engine, the exhaust valve closes and the intake stroke begins again.

[[File:Exhaust_system.jpg]]

==The Main Idea==

Spark plugs are essentially what their namesake says they are: plugs that screw into the cylinders of an engine and produce sparks that ignite fuel in combustion engines during the power stroke. Spark plugs take advantage of Faraday's Law and induction to create large spikes of voltage, typically around 40,000 V, across an electrode gap that would otherwise be impossible to achieve with a regular 12 volt car battery. Their two main functions are to produce spark and to remove heat from the combustion chamber.

===Mechanical Ignition===

Automotive ignition systems are either mechanically or electrically timed and powered by a 12V battery. A mechanically timed ignition system contains a distributor, coil pack, spark plugs, and wires.

[[File:220px-Car_ignition_system.svg.png]]

Each coil in the coil pack consists of a primary winding and a secondary winding, which share a common magnetic core. Both coils are connected to the battery. Additionally, the primary is connected to the distributor and the secondary coil is connected to the spark plugs through the cap and rotor within the distributor. The secondary winding has more turns in its coil, resulting in a much higher voltage that runs through it.

[[File:CarDistributor.jpg|250px]] [[File:Ls2_coil_schematic.jpg|250px]]

Initially, the [https://en.wikipedia.org/wiki/Contact_breaker contact breaker] is closed, completing the circuit and allowing current to flow from the battery, through the primary coil and contact breaker and back through the battery. This flow of current creates a [http://www.physicsbook.gatech.edu/Magnetic_field magnetic field] in the primary's core. The distributor shaft is attached to the camshaft lobes, which dictate when the contact breaker is open or closed. If open, without the current flow, there is no magnetic field. Because this connection is dependent on the cams, there is a cyclical repetition of the existence of a magnetic field. The rapid change of this field causes a large change in [http://www.physicsbook.gatech.edu/Magnetic_Flux magnetic flux]. According to [http://www.physicsbook.gatech.edu/Faraday%27s_Law Faraday's Law], this change in magnetic flux will cause a curly electric field which will induce a large voltage that will be crucial to spark plug function.

[[File:magneticfieldIgsyst.jpg|400px]]

Because the primary coil is wrapped around the secondary coil, a varying magnetic field induces an electric current to be run through the secondary coil, which in turn produces a much larger EMF due to the number of loops in the coil. This will take the inputted DC voltage (again, typically 12-24V) and output 15,000V-40,000V AC. That current is fed to the spark plugs, which have a center electrode that is isolated from grounding electrode, grounded through the spark plug casing to the engine, which shares a ground with the coil. The two electrodes have a gap between them that is set typically between .4mm and 1.7mm. A smaller gap requires less voltage from the coil, a larger gap requires more voltage from the coil. In this case, the spark plug's electrodes act as a capacitor with the air in the cylinder being a dielectric insulator. For a spark to occur, the voltage from the coil must be sufficient to cause dielectric breakdown of the air. As the current crosses the electrodes, there is a drastic raise in the temperature upwards of 60,000K, creating a small spark. When this happens, a click from the spark plug can be heard. This spark ignites the air-fuel mixture in the cylinder continuing the crankshaft motion. The distributor cap and rotor determine which cylinder receives a spark to match the firing order.

===Electronic Ignition===

An electronic ignition system, common among modern cars, solves some of the flaws of the mechanical system: wear, oxidation, and contact of breaker points. Angular sensors replace these breaker points and tell the [https://en.wikipedia.org/wiki/Engine_control_unit engine control unit(ECU)].

[[File:ElectronicIgnitionSystem.jpg]]

A common example, Hall effect sensors, relies on magnetic fields

[[File:Halleffectsensor.gif]] [[File:Mag26.gif]]

===A Mathematical Model===

The primary physics equation used when analyzing spark plugs is Faraday's Law, which states <math>\mathcal{E} = -{{d\Phi_B} \over dt} \ </math>, where <math>\mathcal{E}</math> is the emf produced from the time-varying magnetic flux Φ''B''. The flux is given by <math> \int_{\Sigma} \mathbf{B} \cdot d\mathbf{A}. </math>

The basic equation for dielectric breakdown is given as <math>{{V_d}_b}= {{E_d}_sd}</math>

V''db'' represents the dielectric breakdown voltage and E''ds'' represents the dielectric strength of the insulator and d is the distance. The dielectric strength of air is 3x10^6 V/m, so at a gap of 1mm, the required voltage for dielectric breakdown is 30,000V.

That is a good model for the spark outside of an engine at ambient temperature but there are other variables to consider for voltage required inside of the engine because the dielectric strength will change. If it is assumed the spark plugs have no sort of buildup from carbon or oil, the other variables that effect dielectric breakdown voltage are electrical frequency, temperature, the fact that the dielectric material is not just air but a mixture of gasoline and air at a specific ratio, plus the shape, size, and thickness of the electrodes of the spark plug. The temperature inside of the combustion chamber is typically around 1500 degrees Celcius, increased temperature decreases the dielectric strength. Increased electrical frequency decreases the dielectric strength which is why some manufacturers have researched using higher frequency ignition systems. Gasoline's chemical makeup can vary but Benzene, a component of gasoline, has a dielectric strength of 163x10^6 V/m which is much higher than the dielectric strength of air.

===Explanation of System===
[[File:Spark_plug.gif]]

[https://www.youtube.com/watch?v=__FRCSvEYdE Ignition System Function]
[https://www.youtube.com/watch?v=sFiGsCkAMbk Description of Spark Plug]

==Examples==

http://vicsauto.net/images/anatomy_sparkplug.JPG

Anatomy of a Typical Spark Plug

https://media.boingboing.net/wp-content/uploads/2015/06/skd282544sdc_XS.jpg

Firing Spark Plug

==Connectedness==
Spark Plugs allow gasoline engines to run. The heat from the spark generated by the ignition system causes the gasoline to combust and drive the piston away to turn the crankshaft. This only works if the spark's heat is above the flashpoint of the fuel. Gasoline has a relatively low flashpoint while diesel has a relatively high flashpoint which is why gasoline engines operate at lower pressures with and with spark plugs (spark ignition) and diesels operate at much higher pressures with no spark (compression ignition). Those concepts would apply more so in a course covering thermodynamics. I am a DIY mechanic who works on both gasoline and diesel engines so understanding the physics behind the ignition system of an engine is useful for my tinkering and modifications of the vehicles I work on. A spark ignition system is mostly related to electrical engineering but as it's fundamental concepts are fairly basic in terms of electrical engineering, they are covered in the mechanical engineering curriculum. The stresses, forces and heat generated by combustion are certainly integral concepts of the mechanical engineering curriculum.

==History==
Spark plugs have been around since at least 1859. There are reports that a rudimentary version of the spark plug was originally invented by an African-American man by the name of Edmond Berger in 1839 but he did not patent it. Spark ignition was first used in an early internal combustion engine created by Belgian inventor Étienne Lenoir in 1859. British physicist Sir Oliver Lodge provided many improvements to the design in the 1880s. At the turn of the century, many patents for spark plugs were filed by Nikola Tesla, Robert Bosch, Frederick Richard Simms but Bosch is usually credited with the first commercially viable high-voltage spark plugs (1802) and Albert Champion is credited with expanding its use when he built a spark plug factory in Boston in 1805 and supplied American automobile manufacturers. Sir Oliver Lodge's children started Lodge Plug Company in Britain which allowed the British automobile industry to take off. Similarly, Bosch's spark plugs were largely used by automobile manufacturers in mainland Europe.

Throughout the years, improvements have been made such as adding resistors to the plugs to decrease radio interference, different electrode materials, and the ignition system itself has moved from points and distributors to electronic controllers. Spark plugs have been used in things other than internal combustion engines, such as the second and third stages of the Saturn V rocket.

== See also ==

[http://www.physicsbook.gatech.edu/Magnetic_Field_of_a_Solenoid Magnetic Field of a Solenoid]

[http://www.physicsbook.gatech.edu/Curly_Electric_Fields Curly Electric Fields]

[http://www.physicsbook.gatech.edu/Faraday%27s_Law Faraday's Law]

[http://www.physicsbook.gatech.edu/Inductance Inductance]

[http://www.physicsbook.gatech.edu/Transformers_from_a_physics_standpoint Transformers]

===External links===

[http://www.ngk.com.au/spark-plugs/technical-information/spark-plug-anatomy-construction Spark Plug Anatomy]

==References==

http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/ignition.html

http://auto.howstuffworks.com/spark-plugs.htm

https://www.youtube.com/watch?v=b2udCm7DMzU

http://physics.info/dielectrics/

http://www.engineeringtoolbox.com/liquid-dielectric-constants-d_1263.html

http://www.themotormuseuminminiature.co.uk/inv-jeanjoseph-etienne-lenoir.php

https://www.hemmings.com/magazine/hcc/2006/01/Albert-Champion/1281809.html

http://www.kisouman.com/spark_plug_description-1071.html

http://mechanicstips.blogspot.com/2015/06/how-four-stroke-cycle-engine-works.html

http://www.gsparkplug.com/shop/how-spark-plugs-work/

http://www.mech4study.com/2017/03/magneto-ignition-system-parts-function-working-advantages-and-disadvantages.html

https://www.slideshare.net/jesscar/piston-engines-ignition

http://www.electronics-tutorials.ws/electromagnetism/hall-effect.html

[[Category:Real Life Applications of Electromagnetic Principles]]

File:Mag26.gif

2017-11-28T22:35:38Z

Gellis9:

File:Halleffectsensor.gif

2017-11-28T22:33:21Z

Gellis9:

File:ElectronicIgnitionSystem.jpg

2017-11-28T22:27:30Z

Gellis9:

Spark Plugs

2017-11-28T22:26:52Z

Gellis9: /* Electrical Ignition */

Claimed By Christopher Skretkowicz
Claimed By Edward Mauger Spring 2017
'''Claimed By Geraghty Anne Ellis Fall 2017 (Edits)'''

This page chronicles the inner workings and hidden mechanisms involved with spark plug applications in the real world.

==Basic Engine Theory==

In order to understand how spark plugs work, there must be some background explanation for the systems that use them. Internal combustion engines are those that rely on the ignition of the air-fuel mixture to create the energy used to power most modern vehicles. [The different types [https://en.wikipedia.org/wiki/Two-stroke_engine two-stroke] and four-stroke. [https://auto.howstuffworks.com/rotary-engine4.htm Rotary engines] use the four-stroke cycle but accomplish combustion much differently. Spark plugs are used in all aforementioned applications for the same purpose. For simplicity, the four-stroke IC engine will be discussed in slightly more detail.

There are four main phases or "strokes" for each combustion chamber of the four-stroke engine: intake, compression, power, and exhaust. Regardless of how many cylinders, all of these engines have a firing order - order of which spark plugs are ignited. This sequential order, rather than all firing at once, allows for the continuous motion of the crankshaft.

[[File:IC_engine.jpg]]

[[File:4-Stroke-Engine-with-airflows.gif]] [[File:enginefiringorder.gif]]

===Intake===

Air is pulled into the engine from the environment by the air intake and stored in the plenum. From the plenum, air enters the intake manifold where fuel injectors will distribute the proper ratio of fuel to the amount of air. Naturally aspirated engines (no turbos, superchargers or anything used to force more air into the engine) typically run at a 14:1 air/fuel ratio. The intake manifold is bolted directly onto the engine so that this mixture can enter the combustion chamber or bore. Intake valves during seal the opening to the chamber on the intake side of the engine; during this phase or "stroke" however, they are opened to allow the air-fuel mixture into the bore. [https://en.wikipedia.org/wiki/Piston Pisons], which travel up and down the bore and connected to the crankshaft (see below), are towards the bottom of the bore during this stroke to allow for the most air to enter the combustion chamber and will reach [https://en.wikipedia.org/wiki/Dead_centre_(engineering)#Reciprocating_engine BDC or bottom dead center].

[[File:Ferrari_air_intake_system.jpg|400px]]

[https://en.wikipedia.org/wiki/Camshaft Camshafts] are used to control when these valves(both intake and exhaust, which will be discussed later) open and close and are directly connected to the [https://en.wikipedia.org/wiki/Crankshaft crankshaft], which in short translate the reciprocating motion of the engine to rotational motion which will eventually be translated through the drivetrain to [https://itstillruns.com/car-move-5104221.html propell the vehicle forward.]

===Compression===

In this stroke, the piston moves to the top of the bore, compressing the air-fuel mixture. Both intake and exhaust valves are shut to not allow for any air to escape. Compressing the mixture enables more energy to be expelled when it is ignited and generates heat, which enables the combustion process to happen more quickly after the mixture is ignited. This process follows the ideal gas law in that as pressure is increased and volume decreased, so must the temperature increase.

===Power===

During the power stroke, just before the piston reaches TDC, or top dead center (the very top of the bore), the spark plug ignites creating a combustion reaction. This explosion forces the piston downwards, and so the crankshaft continues to rotate.

===Exhaust===

With the piston moving back up the bore, what remains of the air-fuel mixture after combustion is no longer needed. The camshaft allows the exhaust valve to open and these exhaust gases are pushed out of the combustion chamber through the exhaust manifold, into the [https://en.wikipedia.org/wiki/Catalytic_converter catalytic converter] to lessen the amount of pollution produced, through the [https://en.wikipedia.org/wiki/Muffler muffler] to lessen the noise emitted, and out the tailpipe into the environment.
Back inside the engine, the exhaust valve closes and the intake stroke begins again.

[[File:Exhaust_system.jpg]]

==The Main Idea==

Spark plugs are essentially what their namesake says they are: plugs that screw into the cylinders of an engine and produce sparks that ignite fuel in combustion engines during the power stroke. Spark plugs take advantage of Faraday's Law and induction to create large spikes of voltage, typically around 40,000 V, across an electrode gap that would otherwise be impossible to achieve with a regular 12 volt car battery. Their two main functions are to produce spark and to remove heat from the combustion chamber.

===Mechanical Ignition===

Automotive ignition systems are either mechanically or electrically timed and powered by a 12V battery. A mechanically timed ignition system contains a distributor, coil pack, spark plugs, and wires.

[[File:220px-Car_ignition_system.svg.png]]

Each coil in the coil pack consists of a primary winding and a secondary winding, which share a common magnetic core. Both coils are connected to the battery. Additionally, the primary is connected to the distributor and the secondary coil is connected to the spark plugs through the cap and rotor within the distributor. The secondary winding has more turns in its coil, resulting in a much higher voltage that runs through it.

[[File:CarDistributor.jpg|250px]] [[File:Ls2_coil_schematic.jpg|250px]]

Initially, the [https://en.wikipedia.org/wiki/Contact_breaker contact breaker] is closed, completing the circuit and allowing current to flow from the battery, through the primary coil and contact breaker and back through the battery. This flow of current creates a [http://www.physicsbook.gatech.edu/Magnetic_field magnetic field] in the primary's core. The distributor shaft is attached to the camshaft lobes, which dictate when the contact breaker is open or closed. If open, without the current flow, there is no magnetic field. Because this connection is dependent on the cams, there is a cyclical repetition of the existence of a magnetic field. The rapid change of this field causes a large change in [http://www.physicsbook.gatech.edu/Magnetic_Flux magnetic flux]. According to [http://www.physicsbook.gatech.edu/Faraday%27s_Law Faraday's Law], this change in magnetic flux will cause a curly electric field which will induce a large voltage that will be crucial to spark plug function.

[[File:magneticfieldIgsyst.jpg|400px]]

Because the primary coil is wrapped around the secondary coil, a varying magnetic field induces an electric current to be run through the secondary coil, which in turn produces a much larger EMF due to the number of loops in the coil. This will take the inputted DC voltage (again, typically 12-24V) and output 15,000V-40,000V AC. That current is fed to the spark plugs, which have a center electrode that is isolated from grounding electrode, grounded through the spark plug casing to the engine, which shares a ground with the coil. The two electrodes have a gap between them that is set typically between .4mm and 1.7mm. A smaller gap requires less voltage from the coil, a larger gap requires more voltage from the coil. In this case, the spark plug's electrodes act as a capacitor with the air in the cylinder being a dielectric insulator. For a spark to occur, the voltage from the coil must be sufficient to cause dielectric breakdown of the air. As the current crosses the electrodes, there is a drastic raise in the temperature upwards of 60,000K, creating a small spark. When this happens, a click from the spark plug can be heard. This spark ignites the air-fuel mixture in the cylinder continuing the crankshaft motion. The distributor cap and rotor determine which cylinder receives a spark to match the firing order.

===Electronic Ignition===

===A Mathematical Model===

The primary physics equation used when analyzing spark plugs is Faraday's Law, which states <math>\mathcal{E} = -{{d\Phi_B} \over dt} \ </math>, where <math>\mathcal{E}</math> is the emf produced from the time-varying magnetic flux Φ''B''. The flux is given by <math> \int_{\Sigma} \mathbf{B} \cdot d\mathbf{A}. </math>

The basic equation for dielectric breakdown is given as <math>{{V_d}_b}= {{E_d}_sd}</math>

V''db'' represents the dielectric breakdown voltage and E''ds'' represents the dielectric strength of the insulator and d is the distance. The dielectric strength of air is 3x10^6 V/m, so at a gap of 1mm, the required voltage for dielectric breakdown is 30,000V.

That is a good model for the spark outside of an engine at ambient temperature but there are other variables to consider for voltage required inside of the engine because the dielectric strength will change. If it is assumed the spark plugs have no sort of buildup from carbon or oil, the other variables that effect dielectric breakdown voltage are electrical frequency, temperature, the fact that the dielectric material is not just air but a mixture of gasoline and air at a specific ratio, plus the shape, size, and thickness of the electrodes of the spark plug. The temperature inside of the combustion chamber is typically around 1500 degrees Celcius, increased temperature decreases the dielectric strength. Increased electrical frequency decreases the dielectric strength which is why some manufacturers have researched using higher frequency ignition systems. Gasoline's chemical makeup can vary but Benzene, a component of gasoline, has a dielectric strength of 163x10^6 V/m which is much higher than the dielectric strength of air.

===Explanation of System===
[[File:Spark_plug.gif]]

[https://www.youtube.com/watch?v=__FRCSvEYdE Ignition System Function]
[https://www.youtube.com/watch?v=sFiGsCkAMbk Description of Spark Plug]

==Examples==

http://vicsauto.net/images/anatomy_sparkplug.JPG

Anatomy of a Typical Spark Plug

https://media.boingboing.net/wp-content/uploads/2015/06/skd282544sdc_XS.jpg

Firing Spark Plug

==Connectedness==
Spark Plugs allow gasoline engines to run. The heat from the spark generated by the ignition system causes the gasoline to combust and drive the piston away to turn the crankshaft. This only works if the spark's heat is above the flashpoint of the fuel. Gasoline has a relatively low flashpoint while diesel has a relatively high flashpoint which is why gasoline engines operate at lower pressures with and with spark plugs (spark ignition) and diesels operate at much higher pressures with no spark (compression ignition). Those concepts would apply more so in a course covering thermodynamics. I am a DIY mechanic who works on both gasoline and diesel engines so understanding the physics behind the ignition system of an engine is useful for my tinkering and modifications of the vehicles I work on. A spark ignition system is mostly related to electrical engineering but as it's fundamental concepts are fairly basic in terms of electrical engineering, they are covered in the mechanical engineering curriculum. The stresses, forces and heat generated by combustion are certainly integral concepts of the mechanical engineering curriculum.

==History==
Spark plugs have been around since at least 1859. There are reports that a rudimentary version of the spark plug was originally invented by an African-American man by the name of Edmond Berger in 1839 but he did not patent it. Spark ignition was first used in an early internal combustion engine created by Belgian inventor Étienne Lenoir in 1859. British physicist Sir Oliver Lodge provided many improvements to the design in the 1880s. At the turn of the century, many patents for spark plugs were filed by Nikola Tesla, Robert Bosch, Frederick Richard Simms but Bosch is usually credited with the first commercially viable high-voltage spark plugs (1802) and Albert Champion is credited with expanding its use when he built a spark plug factory in Boston in 1805 and supplied American automobile manufacturers. Sir Oliver Lodge's children started Lodge Plug Company in Britain which allowed the British automobile industry to take off. Similarly, Bosch's spark plugs were largely used by automobile manufacturers in mainland Europe.

Throughout the years, improvements have been made such as adding resistors to the plugs to decrease radio interference, different electrode materials, and the ignition system itself has moved from points and distributors to electronic controllers. Spark plugs have been used in things other than internal combustion engines, such as the second and third stages of the Saturn V rocket.

== See also ==

[http://www.physicsbook.gatech.edu/Magnetic_Field_of_a_Solenoid Magnetic Field of a Solenoid]

[http://www.physicsbook.gatech.edu/Curly_Electric_Fields Curly Electric Fields]

[http://www.physicsbook.gatech.edu/Faraday%27s_Law Faraday's Law]

[http://www.physicsbook.gatech.edu/Inductance Inductance]

[http://www.physicsbook.gatech.edu/Transformers_from_a_physics_standpoint Transformers]

===External links===

[http://www.ngk.com.au/spark-plugs/technical-information/spark-plug-anatomy-construction Spark Plug Anatomy]

==References==

http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/ignition.html

http://auto.howstuffworks.com/spark-plugs.htm

https://www.youtube.com/watch?v=b2udCm7DMzU

http://physics.info/dielectrics/

http://www.engineeringtoolbox.com/liquid-dielectric-constants-d_1263.html

http://www.themotormuseuminminiature.co.uk/inv-jeanjoseph-etienne-lenoir.php

https://www.hemmings.com/magazine/hcc/2006/01/Albert-Champion/1281809.html

http://www.kisouman.com/spark_plug_description-1071.html

http://mechanicstips.blogspot.com/2015/06/how-four-stroke-cycle-engine-works.html

http://www.gsparkplug.com/shop/how-spark-plugs-work/

http://www.mech4study.com/2017/03/magneto-ignition-system-parts-function-working-advantages-and-disadvantages.html

[[Category:Real Life Applications of Electromagnetic Principles]]

Spark Plugs

2017-11-28T22:24:28Z

Gellis9:

Claimed By Christopher Skretkowicz
Claimed By Edward Mauger Spring 2017
'''Claimed By Geraghty Anne Ellis Fall 2017 (Edits)'''

This page chronicles the inner workings and hidden mechanisms involved with spark plug applications in the real world.

==Basic Engine Theory==

In order to understand how spark plugs work, there must be some background explanation for the systems that use them. Internal combustion engines are those that rely on the ignition of the air-fuel mixture to create the energy used to power most modern vehicles. [The different types [https://en.wikipedia.org/wiki/Two-stroke_engine two-stroke] and four-stroke. [https://auto.howstuffworks.com/rotary-engine4.htm Rotary engines] use the four-stroke cycle but accomplish combustion much differently. Spark plugs are used in all aforementioned applications for the same purpose. For simplicity, the four-stroke IC engine will be discussed in slightly more detail.

There are four main phases or "strokes" for each combustion chamber of the four-stroke engine: intake, compression, power, and exhaust. Regardless of how many cylinders, all of these engines have a firing order - order of which spark plugs are ignited. This sequential order, rather than all firing at once, allows for the continuous motion of the crankshaft.

[[File:IC_engine.jpg]]

[[File:4-Stroke-Engine-with-airflows.gif]] [[File:enginefiringorder.gif]]

===Intake===

Air is pulled into the engine from the environment by the air intake and stored in the plenum. From the plenum, air enters the intake manifold where fuel injectors will distribute the proper ratio of fuel to the amount of air. Naturally aspirated engines (no turbos, superchargers or anything used to force more air into the engine) typically run at a 14:1 air/fuel ratio. The intake manifold is bolted directly onto the engine so that this mixture can enter the combustion chamber or bore. Intake valves during seal the opening to the chamber on the intake side of the engine; during this phase or "stroke" however, they are opened to allow the air-fuel mixture into the bore. [https://en.wikipedia.org/wiki/Piston Pisons], which travel up and down the bore and connected to the crankshaft (see below), are towards the bottom of the bore during this stroke to allow for the most air to enter the combustion chamber and will reach [https://en.wikipedia.org/wiki/Dead_centre_(engineering)#Reciprocating_engine BDC or bottom dead center].

[[File:Ferrari_air_intake_system.jpg|400px]]

[https://en.wikipedia.org/wiki/Camshaft Camshafts] are used to control when these valves(both intake and exhaust, which will be discussed later) open and close and are directly connected to the [https://en.wikipedia.org/wiki/Crankshaft crankshaft], which in short translate the reciprocating motion of the engine to rotational motion which will eventually be translated through the drivetrain to [https://itstillruns.com/car-move-5104221.html propell the vehicle forward.]

===Compression===

In this stroke, the piston moves to the top of the bore, compressing the air-fuel mixture. Both intake and exhaust valves are shut to not allow for any air to escape. Compressing the mixture enables more energy to be expelled when it is ignited and generates heat, which enables the combustion process to happen more quickly after the mixture is ignited. This process follows the ideal gas law in that as pressure is increased and volume decreased, so must the temperature increase.

===Power===

During the power stroke, just before the piston reaches TDC, or top dead center (the very top of the bore), the spark plug ignites creating a combustion reaction. This explosion forces the piston downwards, and so the crankshaft continues to rotate.

===Exhaust===

With the piston moving back up the bore, what remains of the air-fuel mixture after combustion is no longer needed. The camshaft allows the exhaust valve to open and these exhaust gases are pushed out of the combustion chamber through the exhaust manifold, into the [https://en.wikipedia.org/wiki/Catalytic_converter catalytic converter] to lessen the amount of pollution produced, through the [https://en.wikipedia.org/wiki/Muffler muffler] to lessen the noise emitted, and out the tailpipe into the environment.
Back inside the engine, the exhaust valve closes and the intake stroke begins again.

[[File:Exhaust_system.jpg]]

==The Main Idea==

Spark plugs are essentially what their namesake says they are: plugs that screw into the cylinders of an engine and produce sparks that ignite fuel in combustion engines during the power stroke. Spark plugs take advantage of Faraday's Law and induction to create large spikes of voltage, typically around 40,000 V, across an electrode gap that would otherwise be impossible to achieve with a regular 12 volt car battery. Their two main functions are to produce spark and to remove heat from the combustion chamber.

===Mechanical Ignition===

Automotive ignition systems are either mechanically or electrically timed and powered by a 12V battery. A mechanically timed ignition system contains a distributor, coil pack, spark plugs, and wires.

[[File:220px-Car_ignition_system.svg.png]]

Each coil in the coil pack consists of a primary winding and a secondary winding, which share a common magnetic core. Both coils are connected to the battery. Additionally, the primary is connected to the distributor and the secondary coil is connected to the spark plugs through the cap and rotor within the distributor. The secondary winding has more turns in its coil, resulting in a much higher voltage that runs through it.

[[File:CarDistributor.jpg|250px]] [[File:Ls2_coil_schematic.jpg|250px]]

Initially, the [https://en.wikipedia.org/wiki/Contact_breaker contact breaker] is closed, completing the circuit and allowing current to flow from the battery, through the primary coil and contact breaker and back through the battery. This flow of current creates a [http://www.physicsbook.gatech.edu/Magnetic_field magnetic field] in the primary's core. The distributor shaft is attached to the camshaft lobes, which dictate when the contact breaker is open or closed. If open, without the current flow, there is no magnetic field. Because this connection is dependent on the cams, there is a cyclical repetition of the existence of a magnetic field. The rapid change of this field causes a large change in [http://www.physicsbook.gatech.edu/Magnetic_Flux magnetic flux]. According to [http://www.physicsbook.gatech.edu/Faraday%27s_Law Faraday's Law], this change in magnetic flux will cause a curly electric field which will induce a large voltage that will be crucial to spark plug function.

[[File:magneticfieldIgsyst.jpg|400px]]

Because the primary coil is wrapped around the secondary coil, a varying magnetic field induces an electric current to be run through the secondary coil, which in turn produces a much larger EMF due to the number of loops in the coil. This will take the inputted DC voltage (again, typically 12-24V) and output 15,000V-40,000V AC. That current is fed to the spark plugs, which have a center electrode that is isolated from grounding electrode, grounded through the spark plug casing to the engine, which shares a ground with the coil. The two electrodes have a gap between them that is set typically between .4mm and 1.7mm. A smaller gap requires less voltage from the coil, a larger gap requires more voltage from the coil. In this case, the spark plug's electrodes act as a capacitor with the air in the cylinder being a dielectric insulator. For a spark to occur, the voltage from the coil must be sufficient to cause dielectric breakdown of the air. As the current crosses the electrodes, there is a drastic raise in the temperature upwards of 60,000K, creating a small spark. When this happens, a click from the spark plug can be heard. This spark ignites the air-fuel mixture in the cylinder continuing the crankshaft motion. The distributor cap and rotor determine which cylinder receives a spark to match the firing order.

===Electrical Ignition===

===A Mathematical Model===

The primary physics equation used when analyzing spark plugs is Faraday's Law, which states <math>\mathcal{E} = -{{d\Phi_B} \over dt} \ </math>, where <math>\mathcal{E}</math> is the emf produced from the time-varying magnetic flux Φ''B''. The flux is given by <math> \int_{\Sigma} \mathbf{B} \cdot d\mathbf{A}. </math>

The basic equation for dielectric breakdown is given as <math>{{V_d}_b}= {{E_d}_sd}</math>

V''db'' represents the dielectric breakdown voltage and E''ds'' represents the dielectric strength of the insulator and d is the distance. The dielectric strength of air is 3x10^6 V/m, so at a gap of 1mm, the required voltage for dielectric breakdown is 30,000V.

That is a good model for the spark outside of an engine at ambient temperature but there are other variables to consider for voltage required inside of the engine because the dielectric strength will change. If it is assumed the spark plugs have no sort of buildup from carbon or oil, the other variables that effect dielectric breakdown voltage are electrical frequency, temperature, the fact that the dielectric material is not just air but a mixture of gasoline and air at a specific ratio, plus the shape, size, and thickness of the electrodes of the spark plug. The temperature inside of the combustion chamber is typically around 1500 degrees Celcius, increased temperature decreases the dielectric strength. Increased electrical frequency decreases the dielectric strength which is why some manufacturers have researched using higher frequency ignition systems. Gasoline's chemical makeup can vary but Benzene, a component of gasoline, has a dielectric strength of 163x10^6 V/m which is much higher than the dielectric strength of air.

===Explanation of System===
[[File:Spark_plug.gif]]

[https://www.youtube.com/watch?v=__FRCSvEYdE Ignition System Function]
[https://www.youtube.com/watch?v=sFiGsCkAMbk Description of Spark Plug]

==Examples==

http://vicsauto.net/images/anatomy_sparkplug.JPG

Anatomy of a Typical Spark Plug

https://media.boingboing.net/wp-content/uploads/2015/06/skd282544sdc_XS.jpg

Firing Spark Plug

==Connectedness==
Spark Plugs allow gasoline engines to run. The heat from the spark generated by the ignition system causes the gasoline to combust and drive the piston away to turn the crankshaft. This only works if the spark's heat is above the flashpoint of the fuel. Gasoline has a relatively low flashpoint while diesel has a relatively high flashpoint which is why gasoline engines operate at lower pressures with and with spark plugs (spark ignition) and diesels operate at much higher pressures with no spark (compression ignition). Those concepts would apply more so in a course covering thermodynamics. I am a DIY mechanic who works on both gasoline and diesel engines so understanding the physics behind the ignition system of an engine is useful for my tinkering and modifications of the vehicles I work on. A spark ignition system is mostly related to electrical engineering but as it's fundamental concepts are fairly basic in terms of electrical engineering, they are covered in the mechanical engineering curriculum. The stresses, forces and heat generated by combustion are certainly integral concepts of the mechanical engineering curriculum.

==History==
Spark plugs have been around since at least 1859. There are reports that a rudimentary version of the spark plug was originally invented by an African-American man by the name of Edmond Berger in 1839 but he did not patent it. Spark ignition was first used in an early internal combustion engine created by Belgian inventor Étienne Lenoir in 1859. British physicist Sir Oliver Lodge provided many improvements to the design in the 1880s. At the turn of the century, many patents for spark plugs were filed by Nikola Tesla, Robert Bosch, Frederick Richard Simms but Bosch is usually credited with the first commercially viable high-voltage spark plugs (1802) and Albert Champion is credited with expanding its use when he built a spark plug factory in Boston in 1805 and supplied American automobile manufacturers. Sir Oliver Lodge's children started Lodge Plug Company in Britain which allowed the British automobile industry to take off. Similarly, Bosch's spark plugs were largely used by automobile manufacturers in mainland Europe.

Throughout the years, improvements have been made such as adding resistors to the plugs to decrease radio interference, different electrode materials, and the ignition system itself has moved from points and distributors to electronic controllers. Spark plugs have been used in things other than internal combustion engines, such as the second and third stages of the Saturn V rocket.

== See also ==

[http://www.physicsbook.gatech.edu/Magnetic_Field_of_a_Solenoid Magnetic Field of a Solenoid]

[http://www.physicsbook.gatech.edu/Curly_Electric_Fields Curly Electric Fields]

[http://www.physicsbook.gatech.edu/Faraday%27s_Law Faraday's Law]

[http://www.physicsbook.gatech.edu/Inductance Inductance]

[http://www.physicsbook.gatech.edu/Transformers_from_a_physics_standpoint Transformers]

===External links===

[http://www.ngk.com.au/spark-plugs/technical-information/spark-plug-anatomy-construction Spark Plug Anatomy]

==References==

http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/ignition.html

http://auto.howstuffworks.com/spark-plugs.htm

https://www.youtube.com/watch?v=b2udCm7DMzU

http://physics.info/dielectrics/

http://www.engineeringtoolbox.com/liquid-dielectric-constants-d_1263.html

http://www.themotormuseuminminiature.co.uk/inv-jeanjoseph-etienne-lenoir.php

https://www.hemmings.com/magazine/hcc/2006/01/Albert-Champion/1281809.html

http://www.kisouman.com/spark_plug_description-1071.html

http://mechanicstips.blogspot.com/2015/06/how-four-stroke-cycle-engine-works.html

http://www.gsparkplug.com/shop/how-spark-plugs-work/

http://www.mech4study.com/2017/03/magneto-ignition-system-parts-function-working-advantages-and-disadvantages.html

[[Category:Real Life Applications of Electromagnetic Principles]]

File:Enginefiringorder.gif

2017-11-28T22:24:16Z

Gellis9:

Spark Plugs

2017-11-28T22:08:46Z

Gellis9:

Claimed By Christopher Skretkowicz
Claimed By Edward Mauger Spring 2017
'''Claimed By Geraghty Anne Ellis Fall 2017 (Edits)'''

This page chronicles the inner workings and hidden mechanisms involved with spark plug applications in the real world.

==Basic Engine Theory==

In order to understand how spark plugs work, there must be some background explanation for the systems that use them. Internal combustion engines are those that rely on the ignition of the air-fuel mixture to create the energy used to power most modern vehicles. [The different types [https://en.wikipedia.org/wiki/Two-stroke_engine two-stroke] and four-stroke. [https://auto.howstuffworks.com/rotary-engine4.htm Rotary engines] use the four-stroke cycle but accomplish combustion much differently. Spark plugs are used in all aforementioned applications for the same purpose. For simplicity, the four-stroke IC engine will be discussed in slightly more detail.

There are four main phases or "strokes" of the four-stroke: intake, compression, power, and exhaust.

[[File:IC_engine.jpg]]

[[File:4-Stroke-Engine-with-airflows.gif]]

===Intake===

Air is pulled into the engine from the environment by the air intake and stored in the plenum. From the plenum, air enters the intake manifold where fuel injectors will distribute the proper ratio of fuel to the amount of air. Naturally aspirated engines (no turbos, superchargers or anything used to force more air into the engine) typically run at a 14:1 air/fuel ratio. The intake manifold is bolted directly onto the engine so that this mixture can enter the combustion chamber or bore. Intake valves during seal the opening to the chamber on the intake side of the engine; during this phase or "stroke" however, they are opened to allow the air-fuel mixture into the bore. [https://en.wikipedia.org/wiki/Piston Pisons], which travel up and down the bore and connected to the crankshaft (see below), are towards the bottom of the bore during this stroke to allow for the most air to enter the combustion chamber and will reach [https://en.wikipedia.org/wiki/Dead_centre_(engineering)#Reciprocating_engine BDC or bottom dead center].

[[File:Ferrari_air_intake_system.jpg|400px]]

[https://en.wikipedia.org/wiki/Camshaft Camshafts] are used to control when these valves(both intake and exhaust, which will be discussed later) open and close and are directly connected to the [https://en.wikipedia.org/wiki/Crankshaft crankshaft], which in short translate the reciprocating motion of the engine to rotational motion which will eventually be translated to [https://itstillruns.com/car-move-5104221.html propell the vehicle forward.]

===Compression===

In this stroke, the piston moves to the top of the bore, compressing the air-fuel mixture. Both intake and exhaust valves are shut to not allow for any air to escape. Compressing the mixture enables more energy to be expelled when it is ignited and generates heat, which enables the combustion process to happen more quickly after the mixture is ignited. This process follows the ideal gas law in that as pressure is increased and volume decreased, so must the temperature increase.

===Power===

During the power stroke, just before the piston reaches TDC, or top dead center (the very top of the bore), the spark plug ignites creating a combustion reaction. This explosion forces the piston downwards, and so the crankshaft continues to rotate.

===Exhaust===

With the piston moving back up the bore, what remains of the air-fuel mixture after combustion is no longer needed. The camshaft allows the exhaust valve to open and these exhaust gases are pushed out of the combustion chamber through the exhaust manifold, into the [https://en.wikipedia.org/wiki/Catalytic_converter catalytic converter] to lessen the amount of pollution produced, through the [https://en.wikipedia.org/wiki/Muffler muffler] to lessen the noise emitted, and out the tailpipe into the environment.
Back inside the engine, the exhaust valve closes and the intake stroke begins again.

[[File:Exhaust_system.jpg]]

==The Main Idea==

Spark plugs are essentially what their namesake says they are: plugs that screw into the cylinders of an engine and produce sparks that ignite fuel in combustion engines during the power stroke. Spark plugs take advantage of Faraday's Law and induction to create large spikes of voltage, typically around 40,000 V, across an electrode gap that would otherwise be impossible to achieve with a regular 12 volt car battery. Their two main functions are to produce spark and to remove heat from the combustion chamber.

===A Mathematical Model===

The primary physics equation used when analyzing spark plugs is Faraday's Law, which states <math>\mathcal{E} = -{{d\Phi_B} \over dt} \ </math>, where <math>\mathcal{E}</math> is the emf produced from the time-varying magnetic flux Φ''B''. The flux is given by <math> \int_{\Sigma} \mathbf{B} \cdot d\mathbf{A}. </math>

===Mechanical Ignition===

Automotive ignition systems are either mechanically or electrically timed and powered by a 12V battery. A mechanically timed ignition system contains a distributor, coil pack, spark plugs, and wires.

[[File:220px-Car_ignition_system.svg.png]]

Each coil in the coil pack consists of a primary winding and a secondary winding, which share a common magnetic core. Both coils are connected to the battery. Additionally, the primary is connected to the distributor and the secondary coil is connected to the spark plugs through the cap and rotor within the distributor. The secondary winding has more turns in its coil, resulting in a much higher voltage that runs through it.

[[File:CarDistributor.jpg|250px]] [[File:Ls2_coil_schematic.jpg|250px]]

Initially, the [https://en.wikipedia.org/wiki/Contact_breaker contact breaker] is closed, completing the circuit and allowing current to flow from the battery, through the primary coil and contact breaker and back through the battery. This flow of current creates a [http://www.physicsbook.gatech.edu/Magnetic_field magnetic field] in the primary's core. The distributor shaft is attached to the camshaft lobes, which dictate when the contact breaker is open or closed. If open, without the current flow, there is no magnetic field. Because this connection is dependent on the cams, there is a cyclical repetition of the existence of a magnetic field. The rapid change of this field causes a large change in [http://www.physicsbook.gatech.edu/Magnetic_Flux magnetic flux]. According to [http://www.physicsbook.gatech.edu/Faraday%27s_Law Faraday's Law], this change in magnetic flux will cause a curly electric field which will induce a large voltage that will be crucial to spark plug function.

[[File:magneticfieldIgsyst.jpg|400px]]

Because the primary coil is wrapped around the secondary coil, a varying magnetic field induces an electric current to be run through the secondary coil, which in turn produces a much larger EMF due to the number of loops in the coil. This will take the inputted DC voltage (again, typically 12-24V) and output 15,000V-40,000V AC. That current is fed to the spark plugs, which have a center electrode that is isolated from grounding electrode which is grounded through the spark plug casing to the engine, which shares a ground with the coil. The two electrodes have a gap between them that is set typically between .4mm and 1.7mm. A smaller gap requires less voltage from the coil, a larger gap requires more voltage from the coil. In this case, the spark plug's electrodes act as a capacitor with the air in the cylinder being a dielectric insulator. For a spark to occur, the voltage from the coil must be sufficient to cause dielectric breakdown of the air. The spark created ignites the fuel in the cylinder which pushes the piston away which turns the crankshaft to create angular momentum which is then transferred through the drivetrain to the wheels of the vehicle.

The basic equation for dielectric breakdown is given as <math>{{V_d}_b}= {{E_d}_sd}</math>

V''db'' represents the dielectric breakdown voltage and E''ds'' represents the dielectric strength of the insulator and d is the distance. The dielectric strength of air is 3x10^6 V/m, so at a gap of 1mm, the required voltage for dielectric breakdown is 30,000V.

That is a good model for the spark outside of an engine at ambient temperature but there are other variables to consider for voltage required inside of the engine because the dielectric strength will change. If it is assumed the spark plugs have no sort of buildup from carbon or oil, the other variables that effect dielectric breakdown voltage are electrical frequency, temperature, the fact that the dielectric material is not just air but a mixture of gasoline and air at a specific ratio, plus the shape, size, and thickness of the electrodes of the spark plug. The temperature inside of the combustion chamber is typically around 1500 degrees Celcius, increased temperature decreases the dielectric strength. Increased electrical frequency decreases the dielectric strength which is why some manufacturers have researched using higher frequency ignition systems. Gasoline's chemical makeup can vary but Benzene, a component of gasoline, has a dielectric strength of 163x10^6 V/m which is much higher than the dielectric strength of air.

===Explanation of System===
[[File:Spark_plug.gif]]

[https://www.youtube.com/watch?v=__FRCSvEYdE Ignition System Function]
[https://www.youtube.com/watch?v=sFiGsCkAMbk Description of Spark Plug]

==Examples==

http://vicsauto.net/images/anatomy_sparkplug.JPG

Anatomy of a Typical Spark Plug

https://media.boingboing.net/wp-content/uploads/2015/06/skd282544sdc_XS.jpg

Firing Spark Plug

==Connectedness==
Spark Plugs allow gasoline engines to run. The heat from the spark generated by the ignition system causes the gasoline to combust and drive the piston away to turn the crankshaft. This only works if the spark's heat is above the flashpoint of the fuel. Gasoline has a relatively low flashpoint while diesel has a relatively high flashpoint which is why gasoline engines operate at lower pressures with and with spark plugs (spark ignition) and diesels operate at much higher pressures with no spark (compression ignition). Those concepts would apply more so in a course covering thermodynamics. I am a DIY mechanic who works on both gasoline and diesel engines so understanding the physics behind the ignition system of an engine is useful for my tinkering and modifications of the vehicles I work on. A spark ignition system is mostly related to electrical engineering but as it's fundamental concepts are fairly basic in terms of electrical engineering, they are covered in the mechanical engineering curriculum. The stresses, forces and heat generated by combustion are certainly integral concepts of the mechanical engineering curriculum.

==History==
Spark plugs have been around since at least 1859. There are reports that a rudimentary version of the spark plug was originally invented by an African-American man by the name of Edmond Berger in 1839 but he did not patent it. Spark ignition was first used in an early internal combustion engine created by Belgian inventor Étienne Lenoir in 1859. British physicist Sir Oliver Lodge provided many improvements to the design in the 1880s. At the turn of the century, many patents for spark plugs were filed by Nikola Tesla, Robert Bosch, Frederick Richard Simms but Bosch is usually credited with the first commercially viable high-voltage spark plugs (1802) and Albert Champion is credited with expanding its use when he built a spark plug factory in Boston in 1805 and supplied American automobile manufacturers. Sir Oliver Lodge's children started Lodge Plug Company in Britain which allowed the British automobile industry to take off. Similarly, Bosch's spark plugs were largely used by automobile manufacturers in mainland Europe.

Throughout the years, improvements have been made such as adding resistors to the plugs to decrease radio interference, different electrode materials, and the ignition system itself has moved from points and distributors to electronic controllers. Spark plugs have been used in things other than internal combustion engines, such as the second and third stages of the Saturn V rocket.

== See also ==

[http://www.physicsbook.gatech.edu/Magnetic_Field_of_a_Solenoid Magnetic Field of a Solenoid]

[http://www.physicsbook.gatech.edu/Curly_Electric_Fields Curly Electric Fields]

[http://www.physicsbook.gatech.edu/Faraday%27s_Law Faraday's Law]

[http://www.physicsbook.gatech.edu/Inductance Inductance]

[http://www.physicsbook.gatech.edu/Transformers_from_a_physics_standpoint Transformers]

===External links===

[http://www.ngk.com.au/spark-plugs/technical-information/spark-plug-anatomy-construction Spark Plug Anatomy]

==References==

http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/ignition.html

http://auto.howstuffworks.com/spark-plugs.htm

https://www.youtube.com/watch?v=b2udCm7DMzU

http://physics.info/dielectrics/

http://www.engineeringtoolbox.com/liquid-dielectric-constants-d_1263.html

http://www.themotormuseuminminiature.co.uk/inv-jeanjoseph-etienne-lenoir.php

https://www.hemmings.com/magazine/hcc/2006/01/Albert-Champion/1281809.html

http://www.kisouman.com/spark_plug_description-1071.html

http://mechanicstips.blogspot.com/2015/06/how-four-stroke-cycle-engine-works.html

http://www.gsparkplug.com/shop/how-spark-plugs-work/

http://www.mech4study.com/2017/03/magneto-ignition-system-parts-function-working-advantages-and-disadvantages.html

[[Category:Real Life Applications of Electromagnetic Principles]]

File:CarDistributor.jpg

2017-11-28T22:03:50Z

Gellis9:

Spark Plugs

2017-11-28T22:00:53Z

Gellis9:

Claimed By Christopher Skretkowicz
Claimed By Edward Mauger Spring 2017
Claimed By Geraghty Anne Ellis Fall 2017 (Edits)

This page chronicles the inner workings and hidden mechanisms involved with spark plug applications in the real world.

==Basic Engine Theory==

In order to understand how spark plugs work, there must be some background explanation for the systems that use them. Internal combustion engines are those that rely on the ignition of the air-fuel mixture to create the energy used to power most modern vehicles. [The different types [https://en.wikipedia.org/wiki/Two-stroke_engine two-stroke] and four-stroke. [https://auto.howstuffworks.com/rotary-engine4.htm Rotary engines] use the four-stroke cycle but accomplish combustion much differently. Spark plugs are used in all aforementioned applications for the same purpose. For simplicity, the four-stroke IC engine will be discussed in slightly more detail.

There are four main phases or "strokes" of the four-stroke: intake, compression, power, and exhaust.

[[File:IC_engine.jpg]]

[[File:4-Stroke-Engine-with-airflows.gif]]

===Intake===

Air is pulled into the engine from the environment by the air intake and stored in the plenum. From the plenum, air enters the intake manifold where fuel injectors will distribute the proper ratio of fuel to the amount of air. Naturally aspirated engines (no turbos, superchargers or anything used to force more air into the engine) typically run at a 14:1 air/fuel ratio. The intake manifold is bolted directly onto the engine so that this mixture can enter the combustion chamber or bore. Intake valves during seal the opening to the chamber on the intake side of the engine; during this phase or "stroke" however, they are opened to allow the air-fuel mixture into the bore. [https://en.wikipedia.org/wiki/Piston Pisons], which travel up and down the bore and connected to the crankshaft (see below), are towards the bottom of the bore during this stroke to allow for the most air to enter the combustion chamber and will reach [https://en.wikipedia.org/wiki/Dead_centre_(engineering)#Reciprocating_engine BDC or bottom dead center].

[[File:Ferrari_air_intake_system.jpg]]

[https://en.wikipedia.org/wiki/Camshaft Camshafts] are used to control when these valves(both intake and exhaust, which will be discussed later) open and close and are directly connected to the [https://en.wikipedia.org/wiki/Crankshaft crankshaft], which in short translate the reciprocating motion of the engine to rotational motion which will eventually be translated to [https://itstillruns.com/car-move-5104221.html propell the vehicle forward.]

===Compression===

In this stroke, the piston moves to the top of the bore, compressing the air-fuel mixture. Both intake and exhaust valves are shut to not allow for any air to escape. Compressing the mixture enables more energy to be expelled when it is ignited and generates heat, which enables the combustion process to happen more quickly after the mixture is ignited. This process follows the ideal gas law in that as pressure is increased and volume decreased, so must the temperature increase.

===Power===

During the power stroke, just before the piston reaches TDC, or top dead center (the very top of the bore), the spark plug ignites creating a combustion reaction. This explosion forces the piston downwards, and so the crankshaft continues to rotate.

===Exhaust===

With the piston moving back up the bore, what remains of the air-fuel mixture after combustion is no longer needed. The camshaft allows the exhaust valve to open and these exhaust gases are pushed out of the combustion chamber through the exhaust manifold, into the [https://en.wikipedia.org/wiki/Catalytic_converter catalytic converter] to lessen the amount of pollution produced, through the [https://en.wikipedia.org/wiki/Muffler muffler] to lessen the noise emitted, and out the tailpipe into the environment.
Back inside the engine, the exhaust valve closes and the intake stroke begins again.

[[File:Exhaust_system.jpg]]

==The Main Idea==

Spark plugs are essentially what their namesake says they are: plugs that screw into the cylinders of an engine and produce sparks that ignite fuel in combustion engines during the power stroke. Spark plugs take advantage of Faraday's Law and induction to create large spikes of voltage, typically around 40,000 V, across an electrode gap that would otherwise be impossible to achieve with a regular 12 volt car battery. Their two main functions are to produce spark and to remove heat from the combustion chamber.

===A Mathematical Model===

The primary physics equation used when analyzing spark plugs is Faraday's Law, which states <math>\mathcal{E} = -{{d\Phi_B} \over dt} \ </math>, where <math>\mathcal{E}</math> is the emf produced from the time-varying magnetic flux Φ''B''. The flux is given by <math> \int_{\Sigma} \mathbf{B} \cdot d\mathbf{A}. </math>

===Mechanical Ignition===

Automotive ignition systems are either mechanically or electrically timed and powered by a 12V battery. A mechanically timed ignition system contains a distributor, coil pack, spark plugs, and wires.

[[File:220px-Car_ignition_system.svg.png]]

Each coil in the coil pack consists of a primary winding and a secondary winding, which share a common magnetic core. Both coils are connected to the battery. Additionally, the primary is connected to the distributor and the secondary coil is connected to the spark plugs through the cap and rotor within the distributor. The secondary winding has more turns in its coil, resulting in a much higher voltage that runs through it.

[[File:Distributor.jpg]]

[[File:Ls2_coil_schematic.jpg]]

Initially, the [https://en.wikipedia.org/wiki/Contact_breaker contact breaker] is closed, completing the circuit and allowing current to flow from the battery, through the primary coil and contact breaker and back through the battery. This flow of current creates a [http://www.physicsbook.gatech.edu/Magnetic_field magnetic field] in the primary's core. The distributor shaft is attached to the camshaft lobes, which dictate when the contact breaker is open or closed. If open, without the current flow, there is no magnetic field. Because this connection is dependent on the cams, there is a cyclical repetition of the existence of a magnetic field. The rapid change of this field causes a large change in [http://www.physicsbook.gatech.edu/Magnetic_Flux magnetic flux]. According to [http://www.physicsbook.gatech.edu/Faraday%27s_Law Faraday's Law], this change in magnetic flux will cause a curly electric field which will induce a large voltage that will be crucial to spark plug function.

[[File:magneticfieldIgsyst.jpg]]

Because the primary coil is wrapped around the secondary coil, a varying magnetic field induces an electric current to be run through the secondary coil, which in turn produces a much larger EMF due to the number of loops in the coil. This will take the inputted DC voltage (again, typically 12-24V) and output 15,000V-40,000V AC. That current is fed to the spark plugs, which have a center electrode that is isolated from grounding electrode which is grounded through the spark plug casing to the engine, which shares a ground with the coil. The two electrodes have a gap between them that is set typically between .4mm and 1.7mm. A smaller gap requires less voltage from the coil, a larger gap requires more voltage from the coil. In this case, the spark plug's electrodes act as a capacitor with the air in the cylinder being a dielectric insulator. For a spark to occur, the voltage from the coil must be sufficient to cause dielectric breakdown of the air. The spark created ignites the fuel in the cylinder which pushes the piston away which turns the crankshaft to create angular momentum which is then transferred through the drivetrain to the wheels of the vehicle.

The basic equation for dielectric breakdown is given as <math>{{V_d}_b}= {{E_d}_sd}</math>

V''db'' represents the dielectric breakdown voltage and E''ds'' represents the dielectric strength of the insulator and d is the distance. The dielectric strength of air is 3x10^6 V/m, so at a gap of 1mm, the required voltage for dielectric breakdown is 30,000V.

That is a good model for the spark outside of an engine at ambient temperature but there are other variables to consider for voltage required inside of the engine because the dielectric strength will change. If it is assumed the spark plugs have no sort of buildup from carbon or oil, the other variables that effect dielectric breakdown voltage are electrical frequency, temperature, the fact that the dielectric material is not just air but a mixture of gasoline and air at a specific ratio, plus the shape, size, and thickness of the electrodes of the spark plug. The temperature inside of the combustion chamber is typically around 1500 degrees Celcius, increased temperature decreases the dielectric strength. Increased electrical frequency decreases the dielectric strength which is why some manufacturers have researched using higher frequency ignition systems. Gasoline's chemical makeup can vary but Benzene, a component of gasoline, has a dielectric strength of 163x10^6 V/m which is much higher than the dielectric strength of air.

===Explanation of System===
[[File:Spark_plug.gif]]

[https://www.youtube.com/watch?v=__FRCSvEYdE Ignition System Function]
[https://www.youtube.com/watch?v=sFiGsCkAMbk Description of Spark Plug]

==Examples==

http://vicsauto.net/images/anatomy_sparkplug.JPG

Anatomy of a Typical Spark Plug

https://media.boingboing.net/wp-content/uploads/2015/06/skd282544sdc_XS.jpg

Firing Spark Plug

==Connectedness==
Spark Plugs allow gasoline engines to run. The heat from the spark generated by the ignition system causes the gasoline to combust and drive the piston away to turn the crankshaft. This only works if the spark's heat is above the flashpoint of the fuel. Gasoline has a relatively low flashpoint while diesel has a relatively high flashpoint which is why gasoline engines operate at lower pressures with and with spark plugs (spark ignition) and diesels operate at much higher pressures with no spark (compression ignition). Those concepts would apply more so in a course covering thermodynamics. I am a DIY mechanic who works on both gasoline and diesel engines so understanding the physics behind the ignition system of an engine is useful for my tinkering and modifications of the vehicles I work on. A spark ignition system is mostly related to electrical engineering but as it's fundamental concepts are fairly basic in terms of electrical engineering, they are covered in the mechanical engineering curriculum. The stresses, forces and heat generated by combustion are certainly integral concepts of the mechanical engineering curriculum.

==History==
Spark plugs have been around since at least 1859. There are reports that a rudimentary version of the spark plug was originally invented by an African-American man by the name of Edmond Berger in 1839 but he did not patent it. Spark ignition was first used in an early internal combustion engine created by Belgian inventor Étienne Lenoir in 1859. British physicist Sir Oliver Lodge provided many improvements to the design in the 1880s. At the turn of the century, many patents for spark plugs were filed by Nikola Tesla, Robert Bosch, Frederick Richard Simms but Bosch is usually credited with the first commercially viable high-voltage spark plugs (1802) and Albert Champion is credited with expanding its use when he built a spark plug factory in Boston in 1805 and supplied American automobile manufacturers. Sir Oliver Lodge's children started Lodge Plug Company in Britain which allowed the British automobile industry to take off. Similarly, Bosch's spark plugs were largely used by automobile manufacturers in mainland Europe.

Throughout the years, improvements have been made such as adding resistors to the plugs to decrease radio interference, different electrode materials, and the ignition system itself has moved from points and distributors to electronic controllers. Spark plugs have been used in things other than internal combustion engines, such as the second and third stages of the Saturn V rocket.

== See also ==

[http://www.physicsbook.gatech.edu/Magnetic_Field_of_a_Solenoid Magnetic Field of a Solenoid]

[http://www.physicsbook.gatech.edu/Curly_Electric_Fields Curly Electric Fields]

[http://www.physicsbook.gatech.edu/Faraday%27s_Law Faraday's Law]

[http://www.physicsbook.gatech.edu/Inductance Inductance]

[http://www.physicsbook.gatech.edu/Transformers_from_a_physics_standpoint Transformers]

===External links===

[http://www.ngk.com.au/spark-plugs/technical-information/spark-plug-anatomy-construction Spark Plug Anatomy]

==References==

http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/ignition.html

http://auto.howstuffworks.com/spark-plugs.htm

https://www.youtube.com/watch?v=b2udCm7DMzU

http://physics.info/dielectrics/

http://www.engineeringtoolbox.com/liquid-dielectric-constants-d_1263.html

http://www.themotormuseuminminiature.co.uk/inv-jeanjoseph-etienne-lenoir.php

https://www.hemmings.com/magazine/hcc/2006/01/Albert-Champion/1281809.html

http://www.kisouman.com/spark_plug_description-1071.html

http://mechanicstips.blogspot.com/2015/06/how-four-stroke-cycle-engine-works.html

http://www.gsparkplug.com/shop/how-spark-plugs-work/

[[Category:Real Life Applications of Electromagnetic Principles]]

File:MagneticfieldIgsyst.jpg

2017-11-28T21:59:52Z

Gellis9:

File:Ls2 coil schematic.jpg

2017-11-28T21:42:54Z

Gellis9:

Spark Plugs

2017-11-28T20:52:02Z

Gellis9:

Claimed By Christopher Skretkowicz
Claimed By Edward Mauger Spring 2017
Claimed By Geraghty Anne Ellis Fall 2017 (Edits)

This page chronicles the inner workings and hidden mechanisms involved with spark plug applications in the real world.

==Basic Engine Theory==

In order to understand how spark plugs work, there must be some background explanation for the systems that use them. Internal combustion engines are those that rely on the ignition of the air-fuel mixture to create the energy used to power most modern vehicles. [The different types [https://en.wikipedia.org/wiki/Two-stroke_engine two-stroke] and four-stroke. [https://auto.howstuffworks.com/rotary-engine4.htm Rotary engines] use the four-stroke cycle but accomplish combustion much differently. Spark plugs are used in all aforementioned applications for the same purpose. For simplicity, the four-stroke IC engine will be discussed in slightly more detail.

There are four main phases or "strokes" of the four-stroke: intake, compression, power, and exhaust.

[[File:IC_engine.jpg]]

[[File:4-Stroke-Engine-with-airflows.gif]]

===Intake===

Air is pulled into the engine from the environment by the air intake and stored in the plenum. From the plenum, air enters the intake manifold where fuel injectors will distribute the proper ratio of fuel to the amount of air. Naturally aspirated engines (no turbos, superchargers or anything used to force more air into the engine) typically run at a 14:1 air/fuel ratio. The intake manifold is bolted directly onto the engine so that this mixture can enter the combustion chamber or bore. Intake valves during seal the opening to the chamber on the intake side of the engine; during this phase or "stroke" however, they are opened to allow the air-fuel mixture into the bore. [https://en.wikipedia.org/wiki/Piston Pisons], which travel up and down the bore and connected to the crankshaft (see below), are towards the bottom of the bore during this stroke to allow for the most air to enter the combustion chamber and will reach [https://en.wikipedia.org/wiki/Dead_centre_(engineering)#Reciprocating_engine BDC or bottom dead center].

[[File:Ferrari_air_intake_system.jpg]]

[https://en.wikipedia.org/wiki/Camshaft Camshafts] are used to control when these valves(both intake and exhaust, which will be discussed later) open and close and are directly connected to the [https://en.wikipedia.org/wiki/Crankshaft crankshaft], which in short translate the reciprocating motion of the engine to rotational motion which will eventually be translated to [https://itstillruns.com/car-move-5104221.html propell the vehicle forward.]

===Compression===

In this stroke, the piston moves to the top of the bore, compressing the air-fuel mixture. Both intake and exhaust valves are shut to not allow for any air to escape. Compressing the mixture enables more energy to be expelled when it is ignited and generates heat, which enables the combustion process to happen more quickly after the mixture is ignited. This process follows the ideal gas law in that as pressure is increased and volume decreased, so must the temperature increase.

===Power===

During the power stroke, just before the piston reaches TDC, or top dead center (the very top of the bore), the spark plug ignites creating a combustion reaction. This explosion forces the piston downwards, and so the crankshaft continues to rotate.

===Exhaust===

With the piston moving back up the bore, what remains of the air-fuel mixture after combustion is no longer needed. The camshaft allows the exhaust valve to open and these exhaust gases are pushed out of the combustion chamber through the exhaust manifold, into the [https://en.wikipedia.org/wiki/Catalytic_converter catalytic converter] to lessen the amount of pollution produced, through the [https://en.wikipedia.org/wiki/Muffler muffler] to lessen the noise emitted, and out the tailpipe into the environment.
Back inside the engine, the exhaust valve closes and the intake stroke begins again.

[[File:Exhaust_system.jpg]]

==The Main Idea==

Spark plugs are essentially what their namesake says they are: plugs that screw into the cylinders of an engine and produce sparks that ignite fuel in combustion engines during the power stroke. Spark plugs take advantage of Faraday's Law and induction to create large spikes of voltage, typically around 40,000 V, across an electrode gap that would otherwise be impossible to achieve with a regular 12 volt car battery. Their two main functions are to produce spark and to remove heat from the combustion chamber.

===A Mathematical Model===

The primary physics equation used when analyzing spark plugs is Faraday's Law, which states <math>\mathcal{E} = -{{d\Phi_B} \over dt} \ </math>, where <math>\mathcal{E}</math> is the emf produced from the time-varying magnetic flux Φ''B''. The flux is given by <math> \int_{\Sigma} \mathbf{B} \cdot d\mathbf{A}. </math>

===Mechanical Ignition===

Automotive ignition systems are either mechanically or electrically timed and powered by a 12V battery. A mechanically timed ignition system contains a distributor, coil pack, spark plugs, and wires.

[[File:220px-Car_ignition_system.svg.png]]

The coil pack, which is grounded to the car, typically consists of 2 coils, a primary coil and a much larger secondary coil, which share a common magnetic core. Both coils are connected to the battery. Current runs from the car battery runs through the primary coil, it is interrupted by a device timed to the camshaft, which varies the electric current running through the circuit. Because the primary coil is wrapped around the secondary coil, a varying magnetic field induces an electric current to be run through the secondary coil, which in turn produces a much larger EMF due to the number of loops in the coil. This will take the inputted DC voltage (again, typically 12-24V) and output 15,000V-40,000V AC. That current is fed to the spark plugs, which have a center electrode that is isolated from grounding electrode which is grounded through the spark plug casing to the engine, which shares a ground with the coil. The two electrodes have a gap between them that is set typically between .4mm and 1.7mm. A smaller gap requires less voltage from the coil, a larger gap requires more voltage from the coil. In this case, the spark plug's electrodes act as a capacitor with the air in the cylinder being a dielectric insulator. For a spark to occur, the voltage from the coil must be sufficient to cause dielectric breakdown of the air. The spark created ignites the fuel in the cylinder which pushes the piston away which turns the crankshaft to create angular momentum which is then transferred through the drivetrain to the wheels of the vehicle.

The basic equation for dielectric breakdown is given as <math>{{V_d}_b}= {{E_d}_sd}</math>

V''db'' represents the dielectric breakdown voltage and E''ds'' represents the dielectric strength of the insulator and d is the distance. The dielectric strength of air is 3x10^6 V/m, so at a gap of 1mm, the required voltage for dielectric breakdown is 30,000V.

That is a good model for the spark outside of an engine at ambient temperature but there are other variables to consider for voltage required inside of the engine because the dielectric strength will change. If it is assumed the spark plugs have no sort of buildup from carbon or oil, the other variables that effect dielectric breakdown voltage are electrical frequency, temperature, the fact that the dielectric material is not just air but a mixture of gasoline and air at a specific ratio, plus the shape, size, and thickness of the electrodes of the spark plug. The temperature inside of the combustion chamber is typically around 1500 degrees Celcius, increased temperature decreases the dielectric strength. Increased electrical frequency decreases the dielectric strength which is why some manufacturers have researched using higher frequency ignition systems. Gasoline's chemical makeup can vary but Benzene, a component of gasoline, has a dielectric strength of 163x10^6 V/m which is much higher than the dielectric strength of air.

===Explanation of System===
[[File:Spark_plug.gif]]

[https://www.youtube.com/watch?v=__FRCSvEYdE Ignition System Function]
[https://www.youtube.com/watch?v=sFiGsCkAMbk Description of Spark Plug]

==Examples==

http://vicsauto.net/images/anatomy_sparkplug.JPG

Anatomy of a Typical Spark Plug

https://media.boingboing.net/wp-content/uploads/2015/06/skd282544sdc_XS.jpg

Firing Spark Plug

==Connectedness==
Spark Plugs allow gasoline engines to run. The heat from the spark generated by the ignition system causes the gasoline to combust and drive the piston away to turn the crankshaft. This only works if the spark's heat is above the flashpoint of the fuel. Gasoline has a relatively low flashpoint while diesel has a relatively high flashpoint which is why gasoline engines operate at lower pressures with and with spark plugs (spark ignition) and diesels operate at much higher pressures with no spark (compression ignition). Those concepts would apply more so in a course covering thermodynamics. I am a DIY mechanic who works on both gasoline and diesel engines so understanding the physics behind the ignition system of an engine is useful for my tinkering and modifications of the vehicles I work on. A spark ignition system is mostly related to electrical engineering but as it's fundamental concepts are fairly basic in terms of electrical engineering, they are covered in the mechanical engineering curriculum. The stresses, forces and heat generated by combustion are certainly integral concepts of the mechanical engineering curriculum.

==History==
Spark plugs have been around since at least 1859. There are reports that a rudimentary version of the spark plug was originally invented by an African-American man by the name of Edmond Berger in 1839 but he did not patent it. Spark ignition was first used in an early internal combustion engine created by Belgian inventor Étienne Lenoir in 1859. British physicist Sir Oliver Lodge provided many improvements to the design in the 1880s. At the turn of the century, many patents for spark plugs were filed by Nikola Tesla, Robert Bosch, Frederick Richard Simms but Bosch is usually credited with the first commercially viable high-voltage spark plugs (1802) and Albert Champion is credited with expanding its use when he built a spark plug factory in Boston in 1805 and supplied American automobile manufacturers. Sir Oliver Lodge's children started Lodge Plug Company in Britain which allowed the British automobile industry to take off. Similarly, Bosch's spark plugs were largely used by automobile manufacturers in mainland Europe.

Throughout the years, improvements have been made such as adding resistors to the plugs to decrease radio interference, different electrode materials, and the ignition system itself has moved from points and distributors to electronic controllers. Spark plugs have been used in things other than internal combustion engines, such as the second and third stages of the Saturn V rocket.

== See also ==

[http://www.physicsbook.gatech.edu/Magnetic_Field_of_a_Solenoid Magnetic Field of a Solenoid]

[http://www.physicsbook.gatech.edu/Curly_Electric_Fields Curly Electric Fields]

[http://www.physicsbook.gatech.edu/Faraday%27s_Law Faraday's Law]

[http://www.physicsbook.gatech.edu/Inductance Inductance]

[http://www.physicsbook.gatech.edu/Transformers_from_a_physics_standpoint Transformers]

===External links===

[http://www.ngk.com.au/spark-plugs/technical-information/spark-plug-anatomy-construction Spark Plug Anatomy]

==References==

http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/ignition.html

http://auto.howstuffworks.com/spark-plugs.htm

https://www.youtube.com/watch?v=b2udCm7DMzU

http://physics.info/dielectrics/

http://www.engineeringtoolbox.com/liquid-dielectric-constants-d_1263.html

http://www.themotormuseuminminiature.co.uk/inv-jeanjoseph-etienne-lenoir.php

https://www.hemmings.com/magazine/hcc/2006/01/Albert-Champion/1281809.html

http://www.kisouman.com/spark_plug_description-1071.html

http://mechanicstips.blogspot.com/2015/06/how-four-stroke-cycle-engine-works.html

http://www.gsparkplug.com/shop/how-spark-plugs-work/

[[Category:Real Life Applications of Electromagnetic Principles]]

File:220px-Car ignition system.svg.png

2017-11-28T20:40:29Z

Gellis9:

Spark Plugs

2017-11-28T20:17:45Z

Gellis9:

Claimed By Christopher Skretkowicz
Claimed By Edward Mauger Spring 2017
Claimed By Geraghty Anne Ellis Fall 2017 (Edits)

This page chronicles the inner workings and hidden mechanisms involved with spark plug applications in the real world.

==Basic Engine Theory==

In order to understand how spark plugs work, there must be some background explanation for the systems that use them. Internal combustion engines are those that rely on the ignition of the air-fuel mixture to create the energy used to power most modern vehicles. [The different types [https://en.wikipedia.org/wiki/Two-stroke_engine two-stroke] and four-stroke. [https://auto.howstuffworks.com/rotary-engine4.htm Rotary engines] use the four-stroke cycle but accomplish combustion much differently. Spark plugs are used in all aforementioned applications for the same purpose. For simplicity, the four-stroke IC engine will be discussed in slightly more detail.

There are four main phases or "strokes" of the four-stroke: intake, compression, power, and exhaust.

[[File:IC_engine.jpg]]

[[File:4-Stroke-Engine-with-airflows.gif]]

===Intake===

Air is pulled into the engine from the environment by the air intake and stored in the plenum. From the plenum, air enters the intake manifold where fuel injectors will distribute the proper ratio of fuel to the amount of air. Naturally aspirated engines (no turbos, superchargers or anything used to force more air into the engine) typically run at a 14:1 air/fuel ratio. The intake manifold is bolted directly onto the engine so that this mixture can enter the combustion chamber or bore. Intake valves during seal the opening to the chamber on the intake side of the engine; during this phase or "stroke" however, they are opened to allow the air-fuel mixture into the bore. [https://en.wikipedia.org/wiki/Piston Pisons], which travel up and down the bore and connected to the crankshaft (see below), are towards the bottom of the bore during this stroke to allow for the most air to enter the combustion chamber and will reach [https://en.wikipedia.org/wiki/Dead_centre_(engineering)#Reciprocating_engine BDC or bottom dead center].

[[File:Ferrari_air_intake_system.jpg]]

[https://en.wikipedia.org/wiki/Camshaft Camshafts] are used to control when these valves(both intake and exhaust, which will be discussed later) open and close and are directly connected to the [https://en.wikipedia.org/wiki/Crankshaft crankshaft], which in short translate the reciprocating motion of the engine to rotational motion which will eventually be translated to [https://itstillruns.com/car-move-5104221.html propell the vehicle forward.]

===Compression===

In this stroke, the piston moves to the top of the bore, compressing the air-fuel mixture. Both intake and exhaust valves are shut to not allow for any air to escape. Compressing the mixture enables more energy to be expelled when it is ignited and generates heat, which enables the combustion process to happen more quickly after the mixture is ignited. This process follows the ideal gas law in that as pressure is increased and volume decreased, so must the temperature increase.

===Power===

During the power stroke, just before the piston reaches TDC, or top dead center (the very top of the bore), the spark plug ignites creating a combustion reaction. This explosion forces the piston downwards, and so the crankshaft continues to rotate.

===Exhaust===

With the piston moving back up the bore, what remains of the air-fuel mixture after combustion is no longer needed. The camshaft allows the exhaust valve to open and these exhaust gases are pushed out of the combustion chamber through the exhaust manifold, into the [https://en.wikipedia.org/wiki/Catalytic_converter catalytic converter] to lessen the amount of pollution produced, through the [https://en.wikipedia.org/wiki/Muffler muffler] to lessen the noise emitted, and out the tailpipe into the environment.
Back inside the engine, the exhaust valve closes and the intake stroke begins again.

[[File:Exhaust_system.jpg]]

==The Main Idea==

Spark plugs are essentially what their namesake says they are: plugs that screw into the cylinders of an engine and produce sparks that ignite fuel in combustion engines. Spark plugs take advantage of Faraday's Law and induction to create large spikes of voltage, typically around 40,000 V, across an electrode gap that would otherwise be impossible to achieve with a regular 12 volt car battery.
===A Mathematical Model===

The primary physics equation used when analyzing spark plugs is Faraday's Law, which states <math>\mathcal{E} = -{{d\Phi_B} \over dt} \ </math>, where <math>\mathcal{E}</math> is the emf produced from the time-varying magnetic flux Φ''B''. The flux is given by <math> \int_{\Sigma} \mathbf{B} \cdot d\mathbf{A}. </math>

The ignition system essentially consists of a coil pack and the spark plugs. The coil pack, which is grounded, typically consists of 2 coils, a primary coil and a much larger secondary coil. As current, typically 12V DC, from the car battery runs through the primary coil, it is interrupted by a device timed to the camshaft, which varies the electric current running through the circuit. Because the primary coil is wrapped around the secondary coil, a varying magnetic field induces an electric current to be run through the secondary coil, which in turn produces a much larger EMF due to the number of loops in the coil. This will take the inputted DC voltage (again, typically 12-24V) and output 15,000V-40,000V AC. That current is fed to the spark plugs, which have a center electrode that is isolated from grounding electrode which is grounded through the spark plug casing to the engine, which shares a ground with the coil. The two electrodes have a gap between them that is set typically between .4mm and 1.7mm. A smaller gap requires less voltage from the coil, a larger gap requires more voltage from the coil. In this case, the spark plug's electrodes act as a capacitor with the air in the cylinder being a dielectric insulator. For a spark to occur, the voltage from the coil must be sufficient to cause dielectric breakdown of the air. The spark created ignites the fuel in the cylinder which pushes the piston away which turns the crankshaft to create angular momentum which is then transferred through the drivetrain to the wheels of the vehicle.

The basic equation for dielectric breakdown is given as <math>{{V_d}_b}= {{E_d}_sd}</math>

V''db'' represents the dielectric breakdown voltage and E''ds'' represents the dielectric strength of the insulator and d is the distance. The dielectric strength of air is 3x10^6 V/m, so at a gap of 1mm, the required voltage for dielectric breakdown is 30,000V.

That is a good model for the spark outside of an engine at ambient temperature but there are other variables to consider for voltage required inside of the engine because the dielectric strength will change. If it is assumed the spark plugs have no sort of buildup from carbon or oil, the other variables that effect dielectric breakdown voltage are electrical frequency, temperature, the fact that the dielectric material is not just air but a mixture of gasoline and air at a specific ratio, plus the shape, size, and thickness of the electrodes of the spark plug. The temperature inside of the combustion chamber is typically around 1500 degrees Celcius, increased temperature decreases the dielectric strength. Increased electrical frequency decreases the dielectric strength which is why some manufacturers have researched using higher frequency ignition systems. Gasoline's chemical makeup can vary but Benzene, a component of gasoline, has a dielectric strength of 163x10^6 V/m which is much higher than the dielectric strength of air.

===Explanation of System===
[[File:Spark_plug.gif]]

[https://www.youtube.com/watch?v=__FRCSvEYdE Ignition System Function]
[https://www.youtube.com/watch?v=sFiGsCkAMbk Description of Spark Plug]

==Examples==

http://vicsauto.net/images/anatomy_sparkplug.JPG

Anatomy of a Typical Spark Plug

https://media.boingboing.net/wp-content/uploads/2015/06/skd282544sdc_XS.jpg

Firing Spark Plug

==Connectedness==
Spark Plugs allow gasoline engines to run. The heat from the spark generated by the ignition system causes the gasoline to combust and drive the piston away to turn the crankshaft. This only works if the spark's heat is above the flashpoint of the fuel. Gasoline has a relatively low flashpoint while diesel has a relatively high flashpoint which is why gasoline engines operate at lower pressures with and with spark plugs (spark ignition) and diesels operate at much higher pressures with no spark (compression ignition). Those concepts would apply more so in a course covering thermodynamics. I am a DIY mechanic who works on both gasoline and diesel engines so understanding the physics behind the ignition system of an engine is useful for my tinkering and modifications of the vehicles I work on. A spark ignition system is mostly related to electrical engineering but as it's fundamental concepts are fairly basic in terms of electrical engineering, they are covered in the mechanical engineering curriculum. The stresses, forces and heat generated by combustion are certainly integral concepts of the mechanical engineering curriculum.

==History==
Spark plugs have been around since at least 1859. There are reports that a rudimentary version of the spark plug was originally invented by an African-American man by the name of Edmond Berger in 1839 but he did not patent it. Spark ignition was first used in an early internal combustion engine created by Belgian inventor Étienne Lenoir in 1859. British physicist Sir Oliver Lodge provided many improvements to the design in the 1880s. At the turn of the century, many patents for spark plugs were filed by Nikola Tesla, Robert Bosch, Frederick Richard Simms but Bosch is usually credited with the first commercially viable high-voltage spark plugs (1802) and Albert Champion is credited with expanding its use when he built a spark plug factory in Boston in 1805 and supplied American automobile manufacturers. Sir Oliver Lodge's children started Lodge Plug Company in Britain which allowed the British automobile industry to take off. Similarly, Bosch's spark plugs were largely used by automobile manufacturers in mainland Europe.

Throughout the years, improvements have been made such as adding resistors to the plugs to decrease radio interference, different electrode materials, and the ignition system itself has moved from points and distributors to electronic controllers. Spark plugs have been used in things other than internal combustion engines, such as the second and third stages of the Saturn V rocket.

== See also ==

[http://www.physicsbook.gatech.edu/Magnetic_Field_of_a_Solenoid Magnetic Field of a Solenoid]

[http://www.physicsbook.gatech.edu/Curly_Electric_Fields Curly Electric Fields]

[http://www.physicsbook.gatech.edu/Faraday%27s_Law Faraday's Law]

[http://www.physicsbook.gatech.edu/Inductance Inductance]

[http://www.physicsbook.gatech.edu/Transformers_from_a_physics_standpoint Transformers]

===External links===

[http://www.ngk.com.au/spark-plugs/technical-information/spark-plug-anatomy-construction Spark Plug Anatomy]

==References==

http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/ignition.html

http://auto.howstuffworks.com/spark-plugs.htm

https://www.youtube.com/watch?v=b2udCm7DMzU

http://physics.info/dielectrics/

http://www.engineeringtoolbox.com/liquid-dielectric-constants-d_1263.html

http://www.themotormuseuminminiature.co.uk/inv-jeanjoseph-etienne-lenoir.php

https://www.hemmings.com/magazine/hcc/2006/01/Albert-Champion/1281809.html

http://www.kisouman.com/spark_plug_description-1071.html

http://mechanicstips.blogspot.com/2015/06/how-four-stroke-cycle-engine-works.html

[[Category:Real Life Applications of Electromagnetic Principles]]

File:Exhaust system.jpg

2017-11-28T20:13:45Z

Gellis9:

Spark Plugs

2017-11-28T19:45:14Z

Gellis9:

Claimed By Christopher Skretkowicz
Claimed By Edward Mauger Spring 2017
Claimed By Geraghty Anne Ellis Fall 2017 (Edits)

This page chronicles the inner workings and hidden mechanisms involved with spark plug applications in the real world.

==Basic Engine Theory==

In order to understand how spark plugs work, there must be some background explanation for the systems that use them. Internal combustion engines are those that rely on the ignition of the air-fuel mixture to create the energy used to power most modern vehicles. [The different types [https://en.wikipedia.org/wiki/Two-stroke_engine two-stroke] and four-stroke. [https://auto.howstuffworks.com/rotary-engine4.htm Rotary engines] use the four-stroke cycle but accomplish combustion much differently. Spark plugs are used in all aforementioned applications for the same purpose. For simplicity, the four-stroke IC engine will be discussed in slightly more detail.

There are four main phases or "strokes" of the four-stroke: intake, compression, power, and exhaust.

[[File:IC_engine.jpg]]

===Intake===

Air is pulled into the engine from the environment by the air intake and stored in the plenum. From the plenum, air enters the intake manifold where fuel injectors will distribute the proper ratio of fuel to the amount of air. Naturally aspirated engines (no turbos, superchargers or anything used to force more air into the engine) typically run at a 14:1 air/fuel ratio. The intake manifold is bolted directly onto the engine so that this mixture can enter the combustion chamber or bore. Intake valves during seal the opening to the chamber on the intake side of the engine; during this phase or "stroke" however, they are opened to allow the air-fuel mixture into the bore. [https://en.wikipedia.org/wiki/Piston Pisons], which travel up and down the bore and connected to the crankshaft (see below), are towards the bottom of the bore during this stroke to allow for the most air to enter the combustion chamber and will reach [https://en.wikipedia.org/wiki/Dead_centre_(engineering)#Reciprocating_engine BDC or bottom dead center].

[[File:Ferrari_air_intake_system.jpg]]

[https://en.wikipedia.org/wiki/Camshaft Camshafts] are used to control when these valves(both intake and exhaust, which will be discussed later) open and close and are directly connected to the [https://en.wikipedia.org/wiki/Crankshaft crankshaft], which in short translate the reciprocating motion of the engine to rotational motion which will eventually be translated to [https://itstillruns.com/car-move-5104221.html propell the vehicle forward.]

===Compression===

In this stroke, the piston moves to the top of the bore, compressing the air-fuel mixture. Both intake and exhaust valves are shut to not allow for any air to escape. Compressing the mixture enables more energy to be expelled when it is ignited and generates heat, which enables the combustion process to happen more quickly after the mixture is ignited. This process follows the ideal gas law in that as pressure is increased and volume decreased, so must the temperature increase.

===Power===

==The Main Idea==

Spark plugs are essentially what their namesake says they are: plugs that screw into the cylinders of an engine and produce sparks that ignite fuel in combustion engines. Spark plugs take advantage of Faraday's Law and induction to create large spikes of voltage, typically around 40,000 V, across an electrode gap that would otherwise be impossible to achieve with a regular 12 volt car battery.
===A Mathematical Model===

The primary physics equation used when analyzing spark plugs is Faraday's Law, which states <math>\mathcal{E} = -{{d\Phi_B} \over dt} \ </math>, where <math>\mathcal{E}</math> is the emf produced from the time-varying magnetic flux Φ''B''. The flux is given by <math> \int_{\Sigma} \mathbf{B} \cdot d\mathbf{A}. </math>

The ignition system essentially consists of a coil pack and the spark plugs. The coil pack, which is grounded, typically consists of 2 coils, a primary coil and a much larger secondary coil. As current, typically 12V DC, from the car battery runs through the primary coil, it is interrupted by a device timed to the camshaft, which varies the electric current running through the circuit. Because the primary coil is wrapped around the secondary coil, a varying magnetic field induces an electric current to be run through the secondary coil, which in turn produces a much larger EMF due to the number of loops in the coil. This will take the inputted DC voltage (again, typically 12-24V) and output 15,000V-40,000V AC. That current is fed to the spark plugs, which have a center electrode that is isolated from grounding electrode which is grounded through the spark plug casing to the engine, which shares a ground with the coil. The two electrodes have a gap between them that is set typically between .4mm and 1.7mm. A smaller gap requires less voltage from the coil, a larger gap requires more voltage from the coil. In this case, the spark plug's electrodes act as a capacitor with the air in the cylinder being a dielectric insulator. For a spark to occur, the voltage from the coil must be sufficient to cause dielectric breakdown of the air. The spark created ignites the fuel in the cylinder which pushes the piston away which turns the crankshaft to create angular momentum which is then transferred through the drivetrain to the wheels of the vehicle.

The basic equation for dielectric breakdown is given as <math>{{V_d}_b}= {{E_d}_sd}</math>

V''db'' represents the dielectric breakdown voltage and E''ds'' represents the dielectric strength of the insulator and d is the distance. The dielectric strength of air is 3x10^6 V/m, so at a gap of 1mm, the required voltage for dielectric breakdown is 30,000V.

That is a good model for the spark outside of an engine at ambient temperature but there are other variables to consider for voltage required inside of the engine because the dielectric strength will change. If it is assumed the spark plugs have no sort of buildup from carbon or oil, the other variables that effect dielectric breakdown voltage are electrical frequency, temperature, the fact that the dielectric material is not just air but a mixture of gasoline and air at a specific ratio, plus the shape, size, and thickness of the electrodes of the spark plug. The temperature inside of the combustion chamber is typically around 1500 degrees Celcius, increased temperature decreases the dielectric strength. Increased electrical frequency decreases the dielectric strength which is why some manufacturers have researched using higher frequency ignition systems. Gasoline's chemical makeup can vary but Benzene, a component of gasoline, has a dielectric strength of 163x10^6 V/m which is much higher than the dielectric strength of air.

===Explanation of System===
[[File:Spark_plug.gif]]

[https://www.youtube.com/watch?v=__FRCSvEYdE Ignition System Function]
[https://www.youtube.com/watch?v=sFiGsCkAMbk Description of Spark Plug]

==Examples==

http://vicsauto.net/images/anatomy_sparkplug.JPG

Anatomy of a Typical Spark Plug

https://media.boingboing.net/wp-content/uploads/2015/06/skd282544sdc_XS.jpg

Firing Spark Plug

==Connectedness==
Spark Plugs allow gasoline engines to run. The heat from the spark generated by the ignition system causes the gasoline to combust and drive the piston away to turn the crankshaft. This only works if the spark's heat is above the flashpoint of the fuel. Gasoline has a relatively low flashpoint while diesel has a relatively high flashpoint which is why gasoline engines operate at lower pressures with and with spark plugs (spark ignition) and diesels operate at much higher pressures with no spark (compression ignition). Those concepts would apply more so in a course covering thermodynamics. I am a DIY mechanic who works on both gasoline and diesel engines so understanding the physics behind the ignition system of an engine is useful for my tinkering and modifications of the vehicles I work on. A spark ignition system is mostly related to electrical engineering but as it's fundamental concepts are fairly basic in terms of electrical engineering, they are covered in the mechanical engineering curriculum. The stresses, forces and heat generated by combustion are certainly integral concepts of the mechanical engineering curriculum.

==History==
Spark plugs have been around since at least 1859. There are reports that a rudimentary version of the spark plug was originally invented by an African-American man by the name of Edmond Berger in 1839 but he did not patent it. Spark ignition was first used in an early internal combustion engine created by Belgian inventor Étienne Lenoir in 1859. British physicist Sir Oliver Lodge provided many improvements to the design in the 1880s. At the turn of the century, many patents for spark plugs were filed by Nikola Tesla, Robert Bosch, Frederick Richard Simms but Bosch is usually credited with the first commercially viable high-voltage spark plugs (1802) and Albert Champion is credited with expanding its use when he built a spark plug factory in Boston in 1805 and supplied American automobile manufacturers. Sir Oliver Lodge's children started Lodge Plug Company in Britain which allowed the British automobile industry to take off. Similarly, Bosch's spark plugs were largely used by automobile manufacturers in mainland Europe.

Throughout the years, improvements have been made such as adding resistors to the plugs to decrease radio interference, different electrode materials, and the ignition system itself has moved from points and distributors to electronic controllers. Spark plugs have been used in things other than internal combustion engines, such as the second and third stages of the Saturn V rocket.

== See also ==

[http://www.physicsbook.gatech.edu/Magnetic_Field_of_a_Solenoid Magnetic Field of a Solenoid]

[http://www.physicsbook.gatech.edu/Curly_Electric_Fields Curly Electric Fields]

[http://www.physicsbook.gatech.edu/Faraday%27s_Law Faraday's Law]

[http://www.physicsbook.gatech.edu/Inductance Inductance]

[http://www.physicsbook.gatech.edu/Transformers_from_a_physics_standpoint Transformers]

===External links===

[http://www.ngk.com.au/spark-plugs/technical-information/spark-plug-anatomy-construction Spark Plug Anatomy]

==References==

http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/ignition.html

http://auto.howstuffworks.com/spark-plugs.htm

https://www.youtube.com/watch?v=b2udCm7DMzU

http://physics.info/dielectrics/

http://www.engineeringtoolbox.com/liquid-dielectric-constants-d_1263.html

http://www.themotormuseuminminiature.co.uk/inv-jeanjoseph-etienne-lenoir.php

https://www.hemmings.com/magazine/hcc/2006/01/Albert-Champion/1281809.html

http://www.kisouman.com/spark_plug_description-1071.html

[[Category:Real Life Applications of Electromagnetic Principles]]

Spark Plugs

2017-11-28T19:36:56Z

Gellis9:

Claimed By Christopher Skretkowicz
Claimed By Edward Mauger Spring 2017
Claimed By Geraghty Anne Ellis Fall 2017 (Edits)

This page chronicles the inner workings and hidden mechanisms involved with spark plug applications in the real world.

==Basic Engine Theory==

In order to understand how spark plugs work, there must be some background explanation for the systems that use them. Internal combustion engines are those that rely on the ignition of the air-fuel mixture to create the energy used to power most modern vehicles. [The different types [https://en.wikipedia.org/wiki/Two-stroke_engine two-stroke] and four-stroke. [https://auto.howstuffworks.com/rotary-engine4.htm Rotary engines] use the four-stroke cycle but accomplish combustion much differently. Spark plugs are used in all aforementioned applications for the same purpose. For simplicity, the four-stroke IC engine will be discussed in slightly more detail.

There are four main phases or "strokes" of the four-stroke: intake, compression, power, and exhaust.

[[File:IC_engine.jpg]]

===Intake===

Air is pulled into the engine from the environment by the air intake and stored in the plenum. From the plenum, air enters the intake manifold where fuel injectors will distribute the proper ratio of fuel to the amount of air. Naturally aspirated engines (no turbos, superchargers or anything used to force more air into the engine) typically run at a 14:1 air/fuel ratio. The intake manifold is bolted directly onto the engine so that this mixture can enter the combustion chamber or bore. Intake valves during seal the opening to the chamber on the intake side of the engine; during this phase or "stroke" however, they are opened to allow the air-fuel mixture into the bore.

[[File:Ferrari_air_intake_system.jpg]]

[https://en.wikipedia.org/wiki/Camshaft Camshafts] are used to control when these valves(both intake and exhaust, which will be discussed later) open and close and are directly connected to the [https://en.wikipedia.org/wiki/Crankshaft crankshaft], which in short translate the reciprocating motion of the engine to rotational motion which will eventually be translated to [https://itstillruns.com/car-move-5104221.html propell the vehicle forward.]

===Compression===

I

==The Main Idea==

Spark plugs are essentially what their namesake says they are: plugs that screw into the cylinders of an engine and produce sparks that ignite fuel in combustion engines. Spark plugs take advantage of Faraday's Law and induction to create large spikes of voltage, typically around 40,000 V, across an electrode gap that would otherwise be impossible to achieve with a regular 12 volt car battery.
===A Mathematical Model===

The primary physics equation used when analyzing spark plugs is Faraday's Law, which states <math>\mathcal{E} = -{{d\Phi_B} \over dt} \ </math>, where <math>\mathcal{E}</math> is the emf produced from the time-varying magnetic flux Φ''B''. The flux is given by <math> \int_{\Sigma} \mathbf{B} \cdot d\mathbf{A}. </math>

The ignition system essentially consists of a coil pack and the spark plugs. The coil pack, which is grounded, typically consists of 2 coils, a primary coil and a much larger secondary coil. As current, typically 12V DC, from the car battery runs through the primary coil, it is interrupted by a device timed to the camshaft, which varies the electric current running through the circuit. Because the primary coil is wrapped around the secondary coil, a varying magnetic field induces an electric current to be run through the secondary coil, which in turn produces a much larger EMF due to the number of loops in the coil. This will take the inputted DC voltage (again, typically 12-24V) and output 15,000V-40,000V AC. That current is fed to the spark plugs, which have a center electrode that is isolated from grounding electrode which is grounded through the spark plug casing to the engine, which shares a ground with the coil. The two electrodes have a gap between them that is set typically between .4mm and 1.7mm. A smaller gap requires less voltage from the coil, a larger gap requires more voltage from the coil. In this case, the spark plug's electrodes act as a capacitor with the air in the cylinder being a dielectric insulator. For a spark to occur, the voltage from the coil must be sufficient to cause dielectric breakdown of the air. The spark created ignites the fuel in the cylinder which pushes the piston away which turns the crankshaft to create angular momentum which is then transferred through the drivetrain to the wheels of the vehicle.

The basic equation for dielectric breakdown is given as <math>{{V_d}_b}= {{E_d}_sd}</math>

V''db'' represents the dielectric breakdown voltage and E''ds'' represents the dielectric strength of the insulator and d is the distance. The dielectric strength of air is 3x10^6 V/m, so at a gap of 1mm, the required voltage for dielectric breakdown is 30,000V.

That is a good model for the spark outside of an engine at ambient temperature but there are other variables to consider for voltage required inside of the engine because the dielectric strength will change. If it is assumed the spark plugs have no sort of buildup from carbon or oil, the other variables that effect dielectric breakdown voltage are electrical frequency, temperature, the fact that the dielectric material is not just air but a mixture of gasoline and air at a specific ratio, plus the shape, size, and thickness of the electrodes of the spark plug. The temperature inside of the combustion chamber is typically around 1500 degrees Celcius, increased temperature decreases the dielectric strength. Increased electrical frequency decreases the dielectric strength which is why some manufacturers have researched using higher frequency ignition systems. Gasoline's chemical makeup can vary but Benzene, a component of gasoline, has a dielectric strength of 163x10^6 V/m which is much higher than the dielectric strength of air.

===Explanation of System===
[[File:Spark_plug.gif]]

[https://www.youtube.com/watch?v=__FRCSvEYdE Ignition System Function]
[https://www.youtube.com/watch?v=sFiGsCkAMbk Description of Spark Plug]

==Examples==

http://vicsauto.net/images/anatomy_sparkplug.JPG

Anatomy of a Typical Spark Plug

https://media.boingboing.net/wp-content/uploads/2015/06/skd282544sdc_XS.jpg

Firing Spark Plug

==Connectedness==
Spark Plugs allow gasoline engines to run. The heat from the spark generated by the ignition system causes the gasoline to combust and drive the piston away to turn the crankshaft. This only works if the spark's heat is above the flashpoint of the fuel. Gasoline has a relatively low flashpoint while diesel has a relatively high flashpoint which is why gasoline engines operate at lower pressures with and with spark plugs (spark ignition) and diesels operate at much higher pressures with no spark (compression ignition). Those concepts would apply more so in a course covering thermodynamics. I am a DIY mechanic who works on both gasoline and diesel engines so understanding the physics behind the ignition system of an engine is useful for my tinkering and modifications of the vehicles I work on. A spark ignition system is mostly related to electrical engineering but as it's fundamental concepts are fairly basic in terms of electrical engineering, they are covered in the mechanical engineering curriculum. The stresses, forces and heat generated by combustion are certainly integral concepts of the mechanical engineering curriculum.

==History==
Spark plugs have been around since at least 1859. There are reports that a rudimentary version of the spark plug was originally invented by an African-American man by the name of Edmond Berger in 1839 but he did not patent it. Spark ignition was first used in an early internal combustion engine created by Belgian inventor Étienne Lenoir in 1859. British physicist Sir Oliver Lodge provided many improvements to the design in the 1880s. At the turn of the century, many patents for spark plugs were filed by Nikola Tesla, Robert Bosch, Frederick Richard Simms but Bosch is usually credited with the first commercially viable high-voltage spark plugs (1802) and Albert Champion is credited with expanding its use when he built a spark plug factory in Boston in 1805 and supplied American automobile manufacturers. Sir Oliver Lodge's children started Lodge Plug Company in Britain which allowed the British automobile industry to take off. Similarly, Bosch's spark plugs were largely used by automobile manufacturers in mainland Europe.

Throughout the years, improvements have been made such as adding resistors to the plugs to decrease radio interference, different electrode materials, and the ignition system itself has moved from points and distributors to electronic controllers. Spark plugs have been used in things other than internal combustion engines, such as the second and third stages of the Saturn V rocket.

== See also ==

[http://www.physicsbook.gatech.edu/Magnetic_Field_of_a_Solenoid Magnetic Field of a Solenoid]

[http://www.physicsbook.gatech.edu/Curly_Electric_Fields Curly Electric Fields]

[http://www.physicsbook.gatech.edu/Faraday%27s_Law Faraday's Law]

[http://www.physicsbook.gatech.edu/Inductance Inductance]

[http://www.physicsbook.gatech.edu/Transformers_from_a_physics_standpoint Transformers]

===External links===

[http://www.ngk.com.au/spark-plugs/technical-information/spark-plug-anatomy-construction Spark Plug Anatomy]

==References==

http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/ignition.html

http://auto.howstuffworks.com/spark-plugs.htm

https://www.youtube.com/watch?v=b2udCm7DMzU

http://physics.info/dielectrics/

http://www.engineeringtoolbox.com/liquid-dielectric-constants-d_1263.html

http://www.themotormuseuminminiature.co.uk/inv-jeanjoseph-etienne-lenoir.php

https://www.hemmings.com/magazine/hcc/2006/01/Albert-Champion/1281809.html

http://www.kisouman.com/spark_plug_description-1071.html

[[Category:Real Life Applications of Electromagnetic Principles]]

File:Ferrari air intake system.jpg

2017-11-28T19:10:15Z

Gellis9: Ferrari 360 Air Intake System

Ferrari 360 Air Intake System

File:IC engine.jpg

2017-11-28T19:02:50Z

Gellis9:

File:Spark plug.gif

2017-11-28T18:53:14Z

Gellis9:

Spark Plugs

2017-11-28T18:52:04Z

Gellis9:

Claimed By Christopher Skretkowicz
Claimed By Edward Mauger Spring 2017
Claimed By Geraghty Anne Ellis Fall 2017 (Edits)

This page chronicles the inner workings and hidden mechanisms involved with spark plug applications in the real world.

==The Main Idea==

Spark plugs are essentially what their namesake says they are: plugs that screw into the cylinders of an engine and produce sparks that ignite fuel in combustion engines. Spark plugs take advantage of Faraday's Law and induction to create large spikes of voltage, typically around 40,000 V, across an electrode gap that would otherwise be impossible to achieve with a regular 12 volt car battery.

===A Mathematical Model===

The primary physics equation used when analyzing spark plugs is Faraday's Law, which states <math>\mathcal{E} = -{{d\Phi_B} \over dt} \ </math>, where <math>\mathcal{E}</math> is the emf produced from the time-varying magnetic flux Φ''B''. The flux is given by <math> \int_{\Sigma} \mathbf{B} \cdot d\mathbf{A}. </math>

The ignition system essentially consists of a coil pack and the spark plugs. The coil pack, which is grounded, typically of 2 coils, a primary coil and a much larger secondary coil. As current, typically 12V DC, from the car battery runs through the primary coil, it is interrupted by a device timed to the camshaft, which varies the electric current running through the circuit. Because the primary coil is wrapped around the secondary coil, a varying magnetic field induces an electric current to be run through the secondary coil, which in turn produces a much larger EMF due to the number of loops in the coil. This will take the inputted DC voltage (again, typically 12-24V) and output 15,000V-40,000V AC. That current is fed to the spark plugs, which have a center electrode that is isolated from grounding electrode which is grounded through the spark plug casing to the engine, which shares a ground with the coil. The two electrodes have a gap between them that is set typically between .4mm and 1.7mm. A smaller gap requires less voltage from the coil, a larger gap requires more voltage from the coil. In this case, the spark plug's electrodes act as a capacitor with the air in the cylinder being a dielectric insulator. For a spark to occur, the voltage from the coil must be sufficient to cause dielectric breakdown of the air. The spark created ignites the fuel in the cylinder which pushes the piston away which turns the crankshaft to create angular momentum which is then transferred through the drivetrain to the wheels of the vehicle.

The basic equation for dielectric breakdown is given as <math>{{V_d}_b}= {{E_d}_sd}</math>

V''db'' represents the dielectric breakdown voltage and E''ds'' represents the dielectric strength of the insulator and d is the distance. The dielectric strength of air is 3x10^6 V/m, so at a gap of 1mm, the required voltage for dielectric breakdown is 30,000V.

That is a good model for the spark outside of an engine at ambient temperature but there are other variables to consider for voltage required inside of the engine because the dielectric strength will change. If it is assumed the spark plugs have no sort of buildup from carbon or oil, the other variables that effect dielectric breakdown voltage are electrical frequency, temperature, the fact that the dielectric material is not just air but a mixture of gasoline and air at a specific ratio, plus the shape, size, and thickness of the electrodes of the spark plug. The temperature inside of the combustion chamber is typically around 1500 degrees Celcius, increased temperature decreases the dielectric strength. Increased electrical frequency decreases the dielectric strength which is why some manufacturers have researched using higher frequency ignition systems. Gasoline's chemical makeup can vary but Benzene, a component of gasoline, has a dielectric strength of 163x10^6 V/m which is much higher than the dielectric strength of air.

===Explanation of System===
[[File:http://www.kisouman.com/images/books/1023/sjdee3003l.gif]]

[https://www.youtube.com/watch?v=__FRCSvEYdE Ignition System Function]
[https://www.youtube.com/watch?v=sFiGsCkAMbk Description of Spark Plug]

==Examples==

http://vicsauto.net/images/anatomy_sparkplug.JPG

Anatomy of a Typical Spark Plug

https://media.boingboing.net/wp-content/uploads/2015/06/skd282544sdc_XS.jpg

Firing Spark Plug

==Connectedness==
Spark Plugs allow gasoline engines to run. The heat from the spark generated by the ignition system causes the gasoline to combust and drive the piston away to turn the crankshaft. This only works if the spark's heat is above the flashpoint of the fuel. Gasoline has a relatively low flashpoint while diesel has a relatively high flashpoint which is why gasoline engines operate at lower pressures with and with spark plugs (spark ignition) and diesels operate at much higher pressures with no spark (compression ignition). Those concepts would apply more so in a course covering thermodynamics. I am a DIY mechanic who works on both gasoline and diesel engines so understanding the physics behind the ignition system of an engine is useful for my tinkering and modifications of the vehicles I work on. A spark ignition system is mostly related to electrical engineering but as it's fundamental concepts are fairly basic in terms of electrical engineering, they are covered in the mechanical engineering curriculum. The stresses, forces and heat generated by combustion are certainly integral concepts of the mechanical engineering curriculum.

==History==
Spark plugs have been around since at least 1859. There are reports that a rudimentary version of the spark plug was originally invented by an African-American man by the name of Edmond Berger in 1839 but he did not patent it. Spark ignition was first used in an early internal combustion engine created by Belgian inventor Étienne Lenoir in 1859. British physicist Sir Oliver Lodge provided many improvements to the design in the 1880s. At the turn of the century, many patents for spark plugs were filed by Nikola Tesla, Robert Bosch, Frederick Richard Simms but Bosch is usually credited with the first commercially viable high-voltage spark plugs (1802) and Albert Champion is credited with expanding its use when he built a spark plug factory in Boston in 1805 and supplied American automobile manufacturers. Sir Oliver Lodge's children started Lodge Plug Company in Britain which allowed the British automobile industry to take off. Similarly, Bosch's spark plugs were largely used by automobile manufacturers in mainland Europe.

Throughout the years, improvements have been made such as adding resistors to the plugs to decrease radio interference, different electrode materials, and the ignition system itself has moved from points and distributors to electronic controllers. Spark plugs have been used in things other than internal combustion engines, such as the second and third stages of the Saturn V rocket.

== See also ==

[http://www.physicsbook.gatech.edu/Magnetic_Field_of_a_Solenoid Magnetic Field of a Solenoid]

[http://www.physicsbook.gatech.edu/Curly_Electric_Fields Curly Electric Fields]

[http://www.physicsbook.gatech.edu/Faraday%27s_Law Faraday's Law]

[http://www.physicsbook.gatech.edu/Inductance Inductance]

[http://www.physicsbook.gatech.edu/Transformers_from_a_physics_standpoint Transformers]

===External links===

[http://www.ngk.com.au/spark-plugs/technical-information/spark-plug-anatomy-construction Spark Plug Anatomy]

==References==

http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/ignition.html

http://auto.howstuffworks.com/spark-plugs.htm

https://www.youtube.com/watch?v=b2udCm7DMzU

http://physics.info/dielectrics/

http://www.engineeringtoolbox.com/liquid-dielectric-constants-d_1263.html

http://www.themotormuseuminminiature.co.uk/inv-jeanjoseph-etienne-lenoir.php

https://www.hemmings.com/magazine/hcc/2006/01/Albert-Champion/1281809.html

[[Category:Real Life Applications of Electromagnetic Principles]]

Spark Plugs

2017-11-28T18:39:50Z

Gellis9:

Claimed By Christopher Skretkowicz
Claimed By Edward Mauger Spring 2017
Claimed By Geraghty Anne Ellis Fall 2017 (Edits)

This page chronicles the inner workings and hidden mechanisms involved with spark plug applications in the real world.

==The Main Idea==

Spark plugs are essentially what their namesake says they are: plugs that screw into the cylinders of an engine and produce sparks that ignite fuel in combustion engines. Spark plugs take advantage of Faraday's Law and induction to create large spikes of voltage that would otherwise be impossible to achieve with a regular 12 volt car battery.

===A Mathematical Model===

The primary physics equation used when analyzing spark plugs is Faraday's Law, which states <math>\mathcal{E} = -{{d\Phi_B} \over dt} \ </math>, where <math>\mathcal{E}</math> is the emf produced from the time-varying magnetic flux Φ''B''. The flux is given by <math> \int_{\Sigma} \mathbf{B} \cdot d\mathbf{A}. </math>

The ignition system essentially consists of a coil pack and the spark plugs. The coil pack, which is grounded, typically of 2 coils, a primary coil and a much larger secondary coil. As current, typically 12V DC, from the car battery runs through the primary coil, it is interrupted by a device timed to the camshaft, which varies the electric current running through the circuit. Because the primary coil is wrapped around the secondary coil, a varying magnetic field induces an electric current to be run through the secondary coil, which in turn produces a much larger EMF due to the number of loops in the coil. This will take the inputted DC voltage (again, typically 12-24V) and output 15,000V-40,000V AC. That current is fed to the spark plugs, which have a center electrode that is isolated from grounding electrode which is grounded through the spark plug casing to the engine, which shares a ground with the coil. The two electrodes have a gap between them that is set typically between .4mm and 1.7mm. A smaller gap requires less voltage from the coil, a larger gap requires more voltage from the coil. In this case, the spark plug's electrodes act as a capacitor with the air in the cylinder being a dielectric insulator. For a spark to occur, the voltage from the coil must be sufficient to cause dielectric breakdown of the air. The spark created ignites the fuel in the cylinder which pushes the piston away which turns the crankshaft to create angular momentum which is then transferred through the drivetrain to the wheels of the vehicle.

The basic equation for dielectric breakdown is given as <math>{{V_d}_b}= {{E_d}_sd}</math>

V''db'' represents the dielectric breakdown voltage and E''ds'' represents the dielectric strength of the insulator and d is the distance. The dielectric strength of air is 3x10^6 V/m, so at a gap of 1mm, the required voltage for dielectric breakdown is 30,000V.

That is a good model for the spark outside of an engine at ambient temperature but there are other variables to consider for voltage required inside of the engine because the dielectric strength will change. If it is assumed the spark plugs have no sort of buildup from carbon or oil, the other variables that effect dielectric breakdown voltage are electrical frequency, temperature, the fact that the dielectric material is not just air but a mixture of gasoline and air at a specific ratio, plus the shape, size, and thickness of the electrodes of the spark plug. The temperature inside of the combustion chamber is typically around 1500 degrees Celcius, increased temperature decreases the dielectric strength. Increased electrical frequency decreases the dielectric strength which is why some manufacturers have researched using higher frequency ignition systems. Gasoline's chemical makeup can vary but Benzene, a component of gasoline, has a dielectric strength of 163x10^6 V/m which is much higher than the dielectric strength of air.

===Explanation of System===

[https://www.youtube.com/watch?v=__FRCSvEYdE Ignition System Function]
[https://www.youtube.com/watch?v=sFiGsCkAMbk Description of Spark Plug]

==Examples==

http://vicsauto.net/images/anatomy_sparkplug.JPG

Anatomy of a Typical Spark Plug

https://media.boingboing.net/wp-content/uploads/2015/06/skd282544sdc_XS.jpg

Firing Spark Plug

==Connectedness==
Spark Plugs allow gasoline engines to run. The heat from the spark generated by the ignition system causes the gasoline to combust and drive the piston away to turn the crankshaft. This only works if the spark's heat is above the flashpoint of the fuel. Gasoline has a relatively low flashpoint while diesel has a relatively high flashpoint which is why gasoline engines operate at lower pressures with and with spark plugs (spark ignition) and diesels operate at much higher pressures with no spark (compression ignition). Those concepts would apply more so in a course covering thermodynamics. I am a DIY mechanic who works on both gasoline and diesel engines so understanding the physics behind the ignition system of an engine is useful for my tinkering and modifications of the vehicles I work on. A spark ignition system is mostly related to electrical engineering but as it's fundamental concepts are fairly basic in terms of electrical engineering, they are covered in the mechanical engineering curriculum. The stresses, forces and heat generated by combustion are certainly integral concepts of the mechanical engineering curriculum.

==History==
Spark plugs have been around since at least 1859. There are reports that a rudimentary version of the spark plug was originally invented by an African-American man by the name of Edmond Berger in 1839 but he did not patent it. Spark ignition was first used in an early internal combustion engine created by Belgian inventor Étienne Lenoir in 1859. British physicist Sir Oliver Lodge provided many improvements to the design in the 1880s. At the turn of the century, many patents for spark plugs were filed by Nikola Tesla, Robert Bosch, Frederick Richard Simms but Bosch is usually credited with the first commercially viable high-voltage spark plugs (1802) and Albert Champion is credited with expanding its use when he built a spark plug factory in Boston in 1805 and supplied American automobile manufacturers. Sir Oliver Lodge's children started Lodge Plug Company in Britain which allowed the British automobile industry to take off. Similarly, Bosch's spark plugs were largely used by automobile manufacturers in mainland Europe.

Throughout the years, improvements have been made such as adding resistors to the plugs to decrease radio interference, different electrode materials, and the ignition system itself has moved from points and distributors to electronic controllers. Spark plugs have been used in things other than internal combustion engines, such as the second and third stages of the Saturn V rocket.

== See also ==

[http://www.physicsbook.gatech.edu/Magnetic_Field_of_a_Solenoid Magnetic Field of a Solenoid]

[http://www.physicsbook.gatech.edu/Curly_Electric_Fields Curly Electric Fields]

[http://www.physicsbook.gatech.edu/Faraday%27s_Law Faraday's Law]

[http://www.physicsbook.gatech.edu/Inductance Inductance]

[http://www.physicsbook.gatech.edu/Transformers_from_a_physics_standpoint Transformers]

===External links===

[http://www.ngk.com.au/spark-plugs/technical-information/spark-plug-anatomy-construction Spark Plug Anatomy]

==References==

http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/ignition.html

http://auto.howstuffworks.com/spark-plugs.htm

https://www.youtube.com/watch?v=b2udCm7DMzU

http://physics.info/dielectrics/

http://www.engineeringtoolbox.com/liquid-dielectric-constants-d_1263.html

http://www.themotormuseuminminiature.co.uk/inv-jeanjoseph-etienne-lenoir.php

https://www.hemmings.com/magazine/hcc/2006/01/Albert-Champion/1281809.html

[[Category:Real Life Applications of Electromagnetic Principles]]