Classification of spark plugs

According to the calorific value, there are cold type and hot type; According to electrode materials, there are nickel alloys, silver alloys, and platinum alloys; If more professional, there are generally several types of spark plugs:
1. Standard spark plug: Its insulation skirt is slightly shrunk into the end face of the housing, and the side electrode is outside the end face of the housing, making it the most widely used type
2. Edge protruding spark plug: The insulation skirt is longer and protrudes beyond the end face of the housing. It has the advantages of large heat absorption capacity, good anti fouling ability, and can be directly cooled by the intake air to lower the temperature, so it is not easy to cause hot ignition, so the thermal adaptation range is wide
3. Electrode type spark plug: Its electrode is very thin, characterized by strong spark and good ignition ability. It can also ensure rapid and reliable engine starting in severe cold seasons, with a wide thermal range and can meet various purposes.
4. Seat type spark plug: Its housing and screw thread are made into a cone, so it can maintain good sealing without gaskets, thereby reducing the volume of the spark plug and making it more advantageous for engine design.
5. Pole type spark plug: The side electrode is generally two or more, with the advantage of reliable ignition and no need for frequent adjustment of the gap. Therefore, it is often used in some gasoline engines where the electrode is prone to erosion and the spark plug gap cannot be adjusted frequently
6. Face Spark Plug: Refers to the surface gap type, which is the coldest type of spark plug. The gap between the center electrode and the end face of the housing is concentric
7. Standard and protruding spark plugs
The standard spark plug is a single electrode spark plug with an insulator skirt end slightly lower than the threaded end face of the housing. It adopts the traditional ignition end structure that is most widely used in side mounted valve engines. To distinguish it from the later "protruding type", this structure is called the "standard type"
The protruding spark plug was originally designed for overhead valve engines. Its insulation skirt protrudes from the threaded end face of the shell and extends into the combustion chamber. Absorbs more heat in the combustion mixture, and has a higher working temperature during combustion to avoid fouling; At high speeds, due to the valve being placed overhead, the airflow drawn in is directed towards the insulator skirt, cooling it and not increasing the maximum temperature much, resulting in a larger thermal range. The protruding spark plug is not suitable for side mounted valve engines due to the large number of bends in the intake duct, and the airflow has little cooling effect on the insulation skirt.
8. Single pole and multi pole spark plugs
Traditional single pole spark plugs have a significant flaw, which is that the side electrode covers the center electrode. When high-voltage discharge occurs between the two poles, the mixture at the spark gap will absorb spark heat and be activated by ionization to form a "fire core". The location where the fire core is formed is generally close to the side electrode, and the heat will be more absorbed by the side electrode, which is the "flame suppression effect" of the electrode. It reduces the spark energy and reduces the ignition performance.