Introduction to the intake and exhaust valves of automobile engines

The function of the automobile valve is to input air into the engine and exhaust the exhaust gas after combustion. The valve consists of the head and stem of the valve. The valve head temperature is very high, but it also bears air pressure. The valve spring force, inertia force of transmission components, and poor lubrication and cooling conditions require the valve to have a certain degree of strength, stiffness, heat resistance, and wear resistance. The intake valve is generally made of alloy steel (chromium steel, nickel chromium steel), and the exhaust valve is made of heat resistant alloy (silicon chromium steel).

Sometimes, in order to save heat resistant alloy, the exhaust valve head is made of heat resistant alloy, the rod is made of chromium steel, and then both are welded. The valve head has a flat top, a ball top, and a horn top. Generally, flat roofs are used. The flat top valve head has simple structure, convenient manufacturing, small heat absorption area, and small mass, and can be used for intake and exhaust valves. The ball top valve is suitable for exhaust valves, with high strength, small exhaust resistance, and good exhaust gas elimination effect. However, it has a large heating area, large mass and inertia, and complex processing. The horn type has a certain streamlined shape, which can reduce the intake resistance, but the head heating area is large, which is only suitable for the intake valve.

The valve cone angle is the angle of the valve sealing surface, which is generally 45 °, and some are 30 ° (CA1091 automobile 6102 engine). The 30 ° valve has the same lift, small valve taper, large valve end face, and low intake resistance. However, due to small taper, thin valve head edge, low stiffness, and poor sealing and thermal conductivity, it is generally used for intake valves.

The thickness of the valve edge is generally 1-3 mm to prevent impact damage or high-temperature combustion with the valve seat during operation. In order to reduce the intake resistance and improve the intake efficiency of the cylinder, most engine intake valves are larger than exhaust valves. The colors of the intake and exhaust valves used also vary.