Spark plug action

What is the role of the spark plug, in fact, it is the ignition coil generated more than 2W volts of high voltage into the engine cylinder, the electrode between the small spark can ignite the mixture in the cylinder to make the engine work normally. The working environment of the spark plug is unimaginably harsh, its "pressure resistance" ability must be strong, the engine does work in four strokes, the temperature is 50-60℃ at the intake stroke, and the pressure is about 90KPa; At the time of ignition, the temperature will instantly rise to about 2000-3000 ° C, and the pressure will also soar to 4000KPa. It should also be able to withstand at least 50 kg/cm2 of explosive force and chemical corrosion of gasoline or gas. This is just a stroke, and the spark plug needs to alternate frequently in such a rapidly heating and cooling environment, not only to be "resistant" but also to be insulated.

Spark plug structure

Spark plug looks small, but the material requirements are very high, the whole is divided into insulation part and metal part. This part of the metal needs to have a certain thread, so that it can be easily screwed into the cylinder. Then the insulator part (generally ceramic body) is pierced with a central electrode, the upper end of which has a wiring nut to carry the pressure wire, and the lower end is welded with a ground electrode. Generally, there is a gap between the center electrode and the ground electrode of 0.6-1.0 mm, and the high voltage electricity through this gap will generate a spark to ignite the mixture. The most critical part of the spark plug is the insulator, if the insulator does not work, the high voltage will "take the path" and avoid the polar area and cannot generate sparks. Therefore, the insulator must have a good resistance to high voltage, high temperature impact, chemical corrosion and other capabilities, many spark plugs are made of alumina based ceramics.

Spark plug type

As long as the size of the engine spark plug is the same, but some screw parts are long, some are shorter. However, there are two types of spark plugs, cold type and hot type. When the spark plug insulator is maintained at a temperature of 500-600 ° C, the oil droplets falling on the insulator can be immediately burned off without forming carbon deposits, higher than this temperature will ignite early, and lower than this temperature there will be carbon deposits. Some insulators have a small heating area, fast heat dissipation and low temperature, which are called cold spark plugs, suitable for high-power engines with high speed and high compression ratio, and some slender and long heating area, slow heat dissipation and high temperature, which are called hot spark plugs, suitable for low-power engines with low compression ratio at medium and low speed. The calorific value of the spark plug represents its heat dissipation speed, the greater the value of the heat dissipation faster, different engines require the use of matching spark plugs, generally fast, high speed, cylinder compression ratio of high need to use a high calorific value of the spark plug, and vice versa. In the new era, there is also a resistance spark plug, which is to install a ceramic resistor of about 5 euros inside the spark plug, which can effectively reduce the ECU on the electric injector to be damaged by interference.

Spark plug number interpretation

Many spark plugs have a string of numbers and letter combinations of numbers, many people do not know what it means. Take F8RTC for example, F indicates the type of spark plug structure; 8 indicates the spark plug heat value, generally 5-8 indicates from hot to cold; R represents resistance type; T represents insulator protrusion type; C indicates that the central electrode conforms to the electrode type of nickel copper.

How about Iridium platinum spark plug

Platinum spark plug is the use of precious metal platinum in the central electrode, the price is more expensive than ordinary spark plugs, its central electrode is quite thin, can effectively improve the ignition ability, help the motorcycle gasoline fully burn, promote the engine stable rotation. And after a long time of use can still maintain this performance, the durability is much higher. There are also iridium gold spark plugs, which have high ignition efficiency and high temperature resistance without thermal degradation.

Spark plug use judgment

When we remove the spark plug to inspect, we can judge by looking at the spark plug surface. By observing the working condition of the spark plug electrode, you can roughly judge whether the engine is working normally.

1: If the spark plug surface is clean and the electrode color is brown, yellow or yellow-white, it indicates good condition.

2: If the electrode surface is wet, it indicates that the gasoline is not fully burned, and it is difficult to start after extinguishing. This often happens after a long period of idling and flailing the throttle.

3: If there is oil stains on the surface of the electrode, it indicates that other oil such as oil has entered the combustion chamber, such as the cylinder, piston and piston ring wear is more serious, the crankcase ventilation device is blocked, causing the oil to slip.

4: If the spark plug surface is black with burning spots, carbon deposits or white indicating that the spark plug is overheating and carbon deposits need to be replaced. It is caused by the mixture being too strong or running under low load conditions for a long time. There is carbon accumulation on the spark plug, which is equivalent to a shunt resistor in parallel between the two electrodes, resulting in premature leakage or weak high-voltage spark.

5: If there is water on the surface of the electrode, it indicates that there is water intrusion in the cylinder, often because the cylinder gasket is not tightly sealed or damaged; The cylinder or cylinder cap is cracked, causing cooling water to enter the cylinder or gasoline mixed with water.

In short, the spark plug is a very critical component, and the performance of the spark plug also directly affects the performance of the vehicle. If the ignition performance of the spark plug is not good, it will not only be difficult to start, the vehicle is weak, and the oil and gas combustion is incomplete, but it will also lead to increased fuel consumption in the long run, and even seriously affect the service life of the engine.

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