A two-stroke engine has no moving valves, and the spark plug fires each time the piston hits the top of its cycle.

二冲程发动机没有移动的阀，火花塞每次点火活塞到达循环顶端。

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However, in a compressed air engine, no additional energy is gained if the air in the cylinder is compressed on the upward stroke of the piston.

然而，在压缩空气引擎，不需要额外的能源是涨，如果空气中的气缸压缩的向上中风活塞。

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With the piston now at BDC and all the gases having been burnt, it is important to remove all the burnt gases from the cylinder on the fourth and final stroke of the cycle of operations.

随着活塞现在位于下止点且所有气体已经燃烧，重要的是要在工作循环的第四个即最后一个冲程中将所有的已燃废气从气缸中排出。

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Conventional four-stroke engines produce power by moving a piston up and down using rapid explosions of fuel and air in a cylindrical chamber.

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