What is the purpose of a spark plug?

[DerekRose]

Spark plugs are a crucial component of the ignition system in gasoline engines. They introduce high-voltage electricity into the combustion chamber and generate a spark by jumping the electrode gap, thereby igniting the combustible air-fuel mixture in the cylinder. Working principle of spark plugs: The ground electrode of the spark plug is connected to the metal shell, which is threaded into the engine block via the cylinder head. The insulator primarily serves to isolate the metal shell from the center electrode. The terminal nut is the part of the spark plug that contacts the high-voltage coil. When current passes through the terminal nut and the center electrode, it ionizes the medium between the center electrode and the ground electrode, producing a spark to ignite the air-fuel mixture in the cylinder. Spark plugs mainly consist of a terminal nut, insulator, terminal stud, center electrode, side electrode, and metal shell. The main types of spark plugs include: standard spark plugs, projected insulator spark plugs, electrode-type spark plugs, seat-type spark plugs, pole-type spark plugs, and surface-gap spark plugs.