Brief introduction of spark plug
Spark plug, commonly known as burner, uses pulse high-voltage electric discharge from high-voltage line (burner line) to break through the air between the two electrodes of spark plug and produce electric spark to ignite the mixture in the cylinder. The main types are quasi-spark plugs, edge protruding spark plugs, electrode spark plugs, seat spark plugs, pole spark plugs and surface jumping spark plugs.
The spark plug is installed on the side or top of the engine. In the early days, the spark plug was connected to the distributor through the cylinder pipeline. In recent ten years, the engines in automobiles have basically been changed into ignition coils, which are directly connected with spark plugs. The working voltage of the spark plug is at least 10000V, and the high voltage electricity is generated by the ignition coil 12V and then transmitted to the spark plug.
Under the action of high voltage, the air between the center electrode and the side electrode of the spark plug will ionize rapidly, forming positively charged ions and negatively charged free electrons. When the voltage between the electrodes reaches a certain value, the number of ions and electrons in the gas will increase like an avalanche, thus making the air lose its insulation.
This gap forms a discharge channel and "breakdown" occurs. At this time, the gas forms a luminous body, that is, a "spark". With its thermal expansion, there is a "snap". The temperature of this electric spark can be as high as 2000 ~ 3000℃, which is enough to ignite the mixed gas in the combustion chamber of the cylinder.