Spark Plug

Spark Plug

Study It

of a Spark Plug

consists of a central electrode enclosed in a ceramic insulator. The other electrode is attached to the underside of a metallic shell provided with a rust resistance finish on its exterior. The lower part of the shell body is provided with threads to fit into the combustion chamber wall.

The

insulator is made pressure-tight in the body by an internal gasket. For making joint b/w combustion chamber & shell body an external copper gasket is used.  The insulators & central electrodes are subjected to high combustion chamber temp. Thus heat must flow from insulator to the metallic shell and then to the combustion chamber wall which is cooled by engine coolent.

Introduction The function of spark plug is to provide a gap in the combustion chamber for the discharge of a high voltage electric pulse that will ignite the air fuel mixture at the desired point in the cycle.

Requirements for Effective Working of Spark Plug • • •

A gap should be maintained fro smooth running of engine every situation. Temp. of any part of the spark plug must . not exceed the pre-ignition temp.(i.e.950 C). Erosion from electric discharge b/w electrodes & that due to chemical action of combustion product is minimum.

Firing

end of the spark plug should have adequate resistance to fouling. Spark plug should withstand fluctuating pressure in the engine cylinder. The spark plug when fitted must be gas tight. It should be capable of conducting high tension current and voltage.

Spark

Plug heat Range