内燃机 diesel engine 柴油机在四个冲程中，只有一个冲程即第二冲程产生功率，这就是为什么柴 油机需要有若干个汽缸，其数目从用于小功率调车机车的4 缸，到用于大功 率干线机车的 16 缸或 16缸以上。各个汽缸的曲柄互相排列成一定的角度， 把柴油机工作周期划分为相应数目的相等部分，这样就保证了曲轴的扭矩十 分均匀It is during one stroke only out of the four, the second, that the engine develops its power, and this is why the diesel engine requires a number of cylinders, from four in a small shunter to sixteen or more in a main line unit of high power, with their cranks set at angles which divided up the circle into a corresponding number of equal parts, so ensuring a perfectly even torque of the crankshaft. 较大功率的汽缸往往按 V 形排列，汽缸在中线的左侧或右侧，以一定角度交 错安排，汽缸以V形排列的柴油机比全部汽缸单列的柴油机更能缩短其总长 度。In the V-type cylinder arrangement, often adopted in the larger diesel engines, setting the cylinders alternately at angle right or left of the centre- line, in a “V” formation, makes possible a reduction in total length as compared with an engine that has all the cylinders in line.也有两冲程的柴油发动机，它的工作循环仅由活塞用一个来回的行程就完成 了。There is also the two-stroke engine, in which the cycle of operation is completed in a single return stroke of the piston.当接近燃烧冲程的末端时，活塞打开一个排气孔，让已用过的废气排出去， 活塞再进一步运动，打开进气孔，空气通过进气孔随着活塞在压力下进入汽 缸。一旦活塞在回程中通过了这两个气孔，就开始压缩空气，刚好在活塞到 达上止点之前，喷射燃油。Near the end of the combustion stroke the piston uncovers an exhaust port, which allows the spent gases to escape, and a further piston movement uncovers the inlet port, through which a charge of air under pressure enters the cylinder behind the piston. As soon as the piston has passed the two ports on the return stroke compression begins, and the oil is injected just before the piston reaches the top of the stroke.两冲程发动机的活塞每次回程都产生燃烧，不像四冲程的活塞每隔一次回程 才产生燃烧，但其功率并不是按比例增大，因为两冲程发动机的效率比四冲 程的效率要低。The power of a two-stroke engine does not go up in proportion to the fact that combustion takes place on every return stroke of the piston, instead of on every alternate return stroke, because the two-stroke engine is less efficient than the four-stroke. 在柴油机的复杂设备中，实际上其核心部分是喷油泵。它是由主轴通过独立 轴上的一系列凸轮驱动的，每个凸轮推动一个汽缸喷油泵的柱塞，那柱塞封 住少量的燃油，并以细雾状射入汽缸活塞上方，然后喷油泵的弹簧使柱塞回 到“停止”位置。Of the complicated equipment of a diesel engine, the most important constituentin effect, the nerve centre is the fuel injection pump. It is driven off the main crankshaft by a series of cams on an independent shaft, and each cam actuates the plunger of one of the cylinders. This plunger traps a small quantity of fuel oil, and delivers it as fine spray into the cylinder above the prison, after which a spring restores the plunger to its out-of-action position. 每隔冲程喷射燃油的数量可以变化，这就使发动机产生的功率发生相应的变 化。The amount of fuel delivered per stroke can be varied, with a proportionate variation in the power developed by the engine.两冲程发动机的凸轮轴转动速度与主轴旋转速度相同，而四冲程发动机则为 主轴转速的一半。另外有一根凸轮轴控制气阀，它准确、及时的打开与关闭 汽缸的进气气孔。In a two-stroke engine the camshaft is rotated at the same speed as the main crankshaft, and in a four-stroke engine at half the speed. Another camshaft works the valves which open and close the cylinder ports at precisely the right moments.校正定时的工作是极其重要，而准确的精密度也是极其重要的，对喷油泵与 气阀某些部件的研磨精密度可达到两万分之一英寸。Correct timing is of the utmost importance, and also extreme accuracy, down to a twenty-thousandth part of an inch, in the grinding of certain parts of the fuel injection pump and the valves. 如果不采取有效的冷却措施，柴油机的器官变得过热就会产生危险。The cylinders of a diesel engine would become dangerously overheated if effective measures were not taken to cool them. 因而每隔器官都围着一个水套，水套形成循环水路的一部分，由水泵驱动水 在回路中不断地流动，并由大型旋转风扇从外部鼓入空气使水冷却。大型旋 转风扇是由主曲轴带动的，而在大型电力传动内燃机车上则由副主电动机来 带动。Each cylinder therefore is encased in a water jacket, which forms part of a circuit through which water is pumped continuously, and cooled by means of air drawn in from the outside atmosphere by large rotary fans, which are worked by the main crankshaft, or in the larger dieselelectric locomotives, by auxiliary motors.在风扇的空气入口处，通常装有带活动叶片的百叶窗，叶片受恒温器控制能 自动的开闭，以保持汽缸温度尽可能稳定。当发动机加大负荷工作时，进来 的空气就多些，而在发动机空转时，进来的空气就少些。The fans are often fitted with movable shutters to their air intakes, which open and close automatically, under the control of thermostats, to keep the cylinder temperature as even as possible, admitting more air when the engine is working hard, and less when it is idling.