best quality Engine Assembly intake exhaust engine valve
2022-02-22
Engine function The function of the valve is to input air into the engine and discharge the exhaust gas after combustion. From the structure of the engine, it is divided into intake valve and exhaust valve. The function of the intake valve is to suck air into the engine and mix it with the fuel; the function of the exhaust valve is to discharge the burned exhaust gas and dissipate heat. composition The valve is composed of a valve head and a stem. The temperature of the valve head is very high (intake valve 570~670K, exhaust valve 1050~1200K), and it also bears the pressure of gas, the force of valve spring and the inertial force of transmission components, its lubrication and cooling conditions are poor, and the valve must be It has certain 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, and the stem is made of chrome steel, and then the two are welded together. The shape of the valve head includes a flat top, a spherical top and a horn top. Usually flat tops are used. The flat top valve head has the advantages of simple structure, convenient manufacture, small heat absorbing area and small mass, and can be used for both Intake And Exhaust Valves. Spherical top valve is suitable for exhaust valve, which has high strength, small exhaust resistance and good exhaust gas elimination effect, but its heating area is large, its mass and inertia are large, and its processing is complicated. The trumpet type has a certain streamlined shape, which can reduce the intake resistance, but its head has a large heating area and 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 type automobile 6102 engine). The 30° valve is considered to have the same lift, the valve taper is small, the valve passing end face is large, and the intake resistance is small, but due to the small taper, the valve head edge is thinner, the stiffness is small, and the sealing and thermal conductivity are poor. on the intake valve. The thickness of the valve edge is generally 1~3mm to prevent damage to the valve seat during work or being burned out by high temperature. In order to reduce the intake resistance and improve the intake efficiency of the cylinder, the intake valve of most engines is larger than the exhaust valve. The used intake and exhaust valves are also different colors. The valve stem has a cylindrical shape, reciprocating continuously in the valve guide, and its surface must be heat treated and polished. The shape of the end of the valve stem depends on the fixing form of the valve spring. The commonly used structure is two halves of the locking piece to fix the spring seat, the end of the valve stem has a ring groove to install the locking piece, and some are fixed with a lock pin. There is a hole for installing the lock pin.
