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。
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.
本文的研究对象，是一台由四气缸母型机变形后的三气缸发动机曲轴圆角设计。
In this paper, we will study a three-cylinder engine which is reformed from a four-cylinder prototype engine.
在发动机气缸里发生的动作，可以分为四个过程或冲程。
The actions taking place in the engine cylinder can be divided into four events or strokes.
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