Valve System（配气机构）

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汽车专业英语——Valve System（配气机构）

Valve System（配气机构）

      Inlet Valve Timing（进气配气定时）
      If the inlet valve opened at TDC of the intake stroke and closed at BDC of that stroke, it would have a duration of 180°.It would have remained open for half of a complete 360° revolution, or 180°. However, it takes some time for the valve to open to its full position. It also takes time for it to close tightly. Therefore the valve is opened before TDC (BTDC) and closed after BDC (ABDC).
      如果进口门在进气行程的上止点打开并且在这次行程的下止点关闭，它将有180°的开度。气门在180°转角内完全打开。然而气门达到全开位置需要一定时间，完全关闭也需要一定时间。因此阀门在上止点(BTDC)之前被打开，在下止点(ABDC)之后关闭。

      Exhaust Valve Timing（排气配气定时）
      If the exhaust valve opened at BDC at the beginning of the exhaust stroke and closed at TDC at the end of the exhaust stroke, it would have a duration of 180°. But like the inlet valve, the exhaust valve needs time to reach the full-open position, It also needs time to reach the full-closed position. So the exhaust valve opens before BDC and closes after TDC.
      如果排气门在排气行程的下止点打开并且在这次行程的上止点关闭，它将有180°的持续。但是像进气门一样，排气门需要时间到达充分打开和关闭的位置。因此排气门在下止点之前打开，在上止点之后关闭。

      Valve Overlap（气门重叠）
      The intake opens at 17° BTDC and the exhaust closes at 17° ATDC. Thus, for a period of 34°, both of the valves are open: (17° + 17° =34°). This period of time is known as valve overlap. The closing of the exhaust valve laps over the opening of the intake valve. During this time, the first of the new mixture pushes the last of the burned gases out the exhaust valve. Valve overlap is held to a minimum on turbo-charged engines. This prevents the intake charge from being blown out the exhaust.
      进气门在上止点前17°打开，排气门在上止点后17°关闭。 因此，有34°的一段时期，两个阀门都是开的：(17°+ 17°= 34°)。这时期被称为气门重叠。排气门的关闭和进气门的开启重叠。在这个时候，新的混合气推动燃烧后