Nickel Alloy/Platinum iridium alloy
Electrode type spark plug, the side electrode is two or more spark plugs.
Its electrodes are very thin, which is characterized by strong sparks and good ignition ability. It can also ensure that the engine starts quickly and reliably in severe cold seasons. It has a wide thermal range and can meet various purposes.
The advantage is that the ignition is reliable and the gap does not need to be adjusted often, so it is often used on some gasoline engines where the electrode is easy to ablate and the spark plug gap cannot be adjusted often.
The gap between the spark plug electrodes has a great impact on the work of the spark plug. If the gap is too small, the spark is weak and it is easy to leak electricity due to carbon deposits. If the gap is too large, the required breakdown voltage is increased, the engine is not easy to start, and at high speeds The “missing” phenomenon is prone to occur, so the spark plug gap should be appropriate. The spark plug gap used in general battery ignition systems is 0.7 ~ 0.8mm, and the individual spark plug gap can reach more than 1.0mm.
Temperature requirements The spark plug insulator skirt (referring to the tapered part of the insulator outside the center electrode of the spark plug) directly contacts the high-temperature gas in the combustion chamber and absorbs a large amount of heat, and the absorbed heat is transmitted to the cylinder head and the atmosphere through the shell, respectively. Experiments show that to ensure the normal operation of the automobile engine, the spark plug insulator skirt should be maintained at a temperature of 500-600 ° C (this temperature is called the self-cleaning temperature of the spark plug). If the temperature is lower than this value, a product will be formed in the insulator skirt. Carbon causes leakage between the electrodes and affects spark plug flashover. If the temperature of the insulator is too high (over 900 ° C), when the mixture comes into contact with such a hot insulator, hot ignition will occur, resulting in premature combustion of the engine. The normal working temperature of the spark plug is between 450 and 870 ° C. The spark plug is now tan. If the working temperature of the spark plug is lower than 450 ℃ for a long time, there will be a lot of carbon deposits around the spark plug, and the spark plug will be black.
Performance requirements The main requirements of spark plugs are thermal characteristics, tensile strength, heat resistance, electrical conductivity, insulation strength, sealing, and corrosion resistance. The spark plug must be heat-resistant. Put the screwed part into a crucible electric furnace or muffle electric furnace that has been heated to 700 ° C for 10 minutes, and then cool it in air. There should be no cracks or seeds on the surface of the insulator. . Spark plug sealing performance requirements: After the heat resistance test, when the air pressure difference is 1 MPa, the air leakage is not allowed to exceed 40 cm3 per minute (if the center electrode is glued with a conductive sealing material, the air leakage is not allowed to exceed 5 cm2 per minute ). Sparks insulator assembly should be able to withstand the power frequency (50Hz) voltage of 2200vV (effective value), which lasts for 30s.