1. Type Valve
From the structure of the engine, into intake valve (intakevalve) and an exhaust valve (exhaustvalve). The intake valve action is air drawn into the engine, the fuel is mixed with combustion; exhaust valves effect the exhaust gas after combustion is discharged and heat dissipation. Classification from the finished valve structure, usually divided into the whole root valve, the valve and the hollow double metal welding charge valve sodium and the like.