Gas distribution phaseIs the actual opening and closing time of inlet and exhaust doors, usually relative toOn,Lower dead pointCrankthrowPositioncrankshaftCircular graph of corner.

Engine in the ventilation process, if the exhaust can be completely, full intake, you can improve the inflation coefficient, increase engine output power.Four strokeFor each working stroke, the crankshaft must turn 180 degrees.Modern engineSpeed is very high, a trip experience a short time (such as Shanghai)SantanaThe four stroke engine, the maximum power of the engine speed up to 5600r/min, a trip time only 0.0054s). Such a short period of intake and exhaust process tends to make the engine inflated or exhaust is not clean, so that engine power down. Therefore, now the engine extends the intake and exhaust time, that is, the valve opening and closing time is not exactlypistonBe inTop dead pointAnd the time of the next stop point, but respectively in advance or delay certaincrankshaftAngle to improve the inlet and exhaust conditions, thereby improving the engineDynamic property。