一、引言作为船舶动力的中速四冲程柴油机,在近10至15年内功率不断上升。所用的主要方法是:高增压,增大缸径到650毫米,平均有效压力提高到21～23巴,提高转速到10转/秒(600转/分),以及爆发压力提高到130～145巴。载重汽车和机车发动机也用这些方法显著提高了功率。发动机的不同部件,如曲轴、连杆、轴承、气缸盖、气门、活塞环和活塞,因功率提高而 I. INTRODUCTION As medium-speed four-stroke diesel engine powered by ships, its power has risen in the recent 10 to 15 years. The main methods used are: high pressurization, increasing the bore diameter to 650 mm, increasing the average effective pressure to 21-23 bar, raising the speed to 10 rev / s (600 revs / min) and increasing the bursting pressure to 130- 145 bar . Heavy truck and locomotive engines also use these methods to significantly increase power. Different parts of the engine, such as crankshaft, connecting rod, bearings, cylinder head, valves, piston rings and pistons, due to increased power