The function of the valve is to input the air into the engine and exhaust the waste gas after combustion. The valves are divided into intake valves and exhaust valves, from the engine structure. The purpose of the intake valve is to draw air into the engine and mix it with fuel for combustion; and the function of the exhaust valve is to exhaust the waste gas after combustion and dissipate heat.The valve is composed of a valve head and a rod. Valve head temperature is very high (intake valve 570~670K, exhaust valve 1050~1200K). And they also bear the gas pressure, valve spring force and transmission component inertia force. The poor lubrication and cooling condition requires that the valve must have a certain strength, stiffness, heat and wear resistance.
