The spark plug is an important part of supporting the work of the gasoline engine (diesel engine is compression ignition to do work, there is no spark plug), but the body is not big, but the inside knowledge is not small, today we will talk about the basic knowledge of replacing the spark plug need to pay attention to facilitate you in the election When buying spark plugs, they choose to be more accurate and have more bottom in their hearts. â—Working principle The role of the spark plug is to pulsate the high-voltage pulse released by the ignition coil into a spark at the tip to ignite the gas-oil mixture in the cylinder to do work. In the most general terms, it is equivalent to the flint of a lighter, an activated component. The main structure of the spark plug is: 1, wiring screw; 2, central electrode; 3, grounding electrode; 4, metal shell; 5, insulator, the most important of which is the two electrodes. More basic knowledge This article will not go into details, I would like to know more spark plug knowledge I recommend you to read this article: "Practical Technical Manual (4) spark plug technology Secret." Let's talk about what we need to know before replacing the spark plug. ★ Choose the hard index of spark plug 1, size Replace spark plugs must choose the size suitable for their own vehicles, length and diameter should be consistent, this does not really have to say how to judge, if you buy the wrong model is not installed, even if you can live on to install, the size of the subtle differences will also be performance Causes adverse effects, and severe injuries can damage the engine. Each spark plug has its model printed on it. The second letter of the string represents the size of the spark plug, which also includes the diameter and length of the thread. Thread diameter Thread diameters are mainly 10mm, 12mm, and 14mm. In China, 14mm is the most popular size, but as the engine design becomes more and more compact, various parts will also be miniaturized. It is no exception, the trend of smaller tapering has been set, and the next 10mm, 12mm and other finer spark plugs will become the mainstream. Thread length There is also an important size is the length of the thread, there are many friends commonly known as it "tooth length", there are many kinds of models in the list, but for the average user to remember these models is too difficult, not too much Meaning, you just need to remember what size spark plugs your car needs to change. A friend will ask what model my car is? This problem has been found in the product descriptions of the major spark plug manufacturers. Finding the spark plug model corresponding to their own model is all right. It is not difficult. 2, heat value The calorific value is also very important. The most common explanation is the spark plug's own heat dissipation capability. However, different manufacturers have different rules for naming the spark plug's calorific value, so it cannot be summarized as “high†or “low†calorific value. It can be simply It is divided into "cold" spark plugs with good heat dissipation and "hot" spark plugs suitable for low-speed engines. For example, the spark plug of the championship means that the larger the value is, the more the spark plug is biased toward the "hot type", and the larger the value of the NGK spark plug is, the more the month is biased towards the "cold type." When selecting the spark plug, it must be selected according to the matching heating value of the vehicle. If the choice is not consistent, the performance of the engine will be affected. Cold spark plug: The higher the spark plug's heat value, the better the cooling capacity. This type of spark plug is more suitable for high-powered engines. The disadvantage of this kind of spark plug is that due to faster heat dissipation, it is easier for a small-displacement engine to produce a product. Carbon, and the most serious consequence of carbon deposition is ignition misfire. If you are driving a high-powered car or a high-speed "speed car," you can consider this kind of spark plug. Thermal spark plugs: At the same operating temperature, carbon deposition is not easy, but the heat dissipation capability is relatively poor, and is suitable for use in household cars that do not pursue dynamic performance. The disadvantage is that if the thermal value of the thermal spark plug is too high, pre-ignition and knock may occur. Different engines have different requirements for the heat value of spark plugs. High-power engines and good power are recommended to choose cold type spark plugs for good heat dissipation; small-displacement engines are recommended to select hot spark plugs, which are not prone to carbon deposition. It should be noted that different spark plug manufacturers have different ways of expressing calorific value. For example, the higher the value of a champion brand is, the more it is biased toward the model. The larger the value of NGK brand is, the more it is biased toward the cold type. Therefore, when purchasing a spark plug, it must be based on The spark plugs are selected according to the calorific value of different models in the product catalog. After the two parameters of size and calorific value are determined, it can be ensured that the spark plug can meet the normal use. As for the performance and life expectancy, it depends on the material and other parameters. ★The effect of spark plug material on performance The spark plug is composed of two parts, the iron shell and the central ceramic body. The ceramic body also contains the wiring screw and the electrode. The "some gold" that we normally choose when talking about the spark plug is the material of the small electrode. The material of other components is negligible for engine performance. The electrode materials commonly found in the market today are copper, nickel alloys, platinum, and osmium gold (both platinum and yttrium are commonly referred to as precious metals). The conductivity of metals increases from left to right (copper, nickel alloy, platinum, and gold). ) The voltage required for ignition decreases from left to right (copper> nickel alloy> platinum> Sheet Metal), so the noble metal spark plug has a smaller load on the engine, which is beneficial to reduce fuel consumption; in addition, the precious metal has a longer service life, of course, the price Also with the increase of performance, the price of sheet metal spark plugs is generally more than one hundred yuan. Casting aluminum is a kind of aluminum alloy which is filled with molten metal to obtain blank of various shape parts.It has the advantages of low density, high specific strength, good corrosion resistance and casting technology, and is limited by the structural design of parts.It is divided into medium strength alloys based on al-si and al-si-mg-cu.High strength alloy based on al-cu;Al-mg based corrosion resistant alloy;Al-Re - based hot - strength alloy.Most heat treatment is required to strengthen the alloy, eliminate the internal stress of the casting, stabilize the structure and size of the parts.Used for making beam, fuel turbine blade, pump body, hanger, wheel hub, intake port and engine casing etc.It is also used for making cylinder cover, gearbox and piston of automobile, shell of instrument meter and pump of supercharger. 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