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Spark Plug, Main Parts & Types of spark plug - Mechanical Education

Spark Plug:

Spark Plug: A Spark Plug is one of the main part of the engine which is provided on the top of the cylinder, without the spark plug, petrol engines don't ignite the air-fuel mixture which is supplied to the cylinder. with the help of spark plug, a high voltage can be generated in the cylinder and makes the fuel to burn. a spark plug should be made with strong material and high-temperature resistance. this is also works as an airtight fitting on the cylinder which does not allow to escape the air-fuel burning from the cylinder.

Spark Plug is used to produce an electric spark which used to ignite the compressed air-fuel mixture in a closed cylinder. this is only used in spark ignition engines.
To produce an high voltage current in spark plug it is connected to a current carrying coil and is spark is produced by the help of a battery system.
This is placed on the top of the cylinder, the spark is produced between the electrodes by supplying the high voltage current to it.
Spark Plug is made with metal which consists of electrodes in it. these electrodes are used to insulated with each other this is because to avoid short circuit.
To produce a spark in the plug the gap between the grounded electrode and the center electrode plays an important role and there is an important consideration of plug tip, depending upon the temperature present in the cylinder the tip of the plug gets heated and this leads to pre-ignition and knocking.

Main parts of Spark Plug:

The Following are the main Parts of  Spark Plug:
  • Ribs
  • Insulator
  • Central Electrode
  • Shell
  • Sealing Matreial
  • Gap
This are used to work as an electrical insulator and this is used to prevent the leaking of electrical energy.

Due to the high temperature developed in the cylinder insulator supports the center electrode.

Central electrode:
This is used to flow the electrons and this should have ability to resist from corrosion and erosion.

This is the cover part of the plug which protects the outer surface from damages.

Sealing material:
This is used to protect from leakages which is protecting the cylinder from leakage losses.

This is the area between center electrode and ground electrode.

Spark plug is used only in petrol engines due to the self-ignition temperature is 240degress.
According to the weather condition or working process, there are few types.

Types of Spark Plugs:

The following are the different types of Spark Plug
  • Hot Plug
  • Cold Plug
Hot plug is used in cold weather conditions
Cold plugs are used to avoid pre-ignition and where there is high output power.
And also according to the thread length, there is the short type and long type.
This spark plug should withstand to maximum pressure.
This should have high resistance to erosion to do not get damages to it.
It should have high thermal resistance and there should be gas-tight joints between parts.
All the petrol engines required this plug to ignite the air-fuel mixture, in petrol engine the compression ratio is less than diesel due to this the air-fuel mixture does not compressed highly but burns with the help of spark produced by the spark plug.
This type of process helps to produce less vibration in the cylinder.


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