柴油机缸内机油消耗量的仿真计算及影响因素分析

为了降低发动机的机油消耗量,分析了发动机缸内机油消耗的4种主要模式,并以某柴油机为例,通过仿真的方法对某些常用工况下这4种模式的机油消耗量进行了计算,发现其中缸壁蒸发的机油量占了大部分.然后分析了柴油机不同运行工况、第2道活塞环闭口间隙及各道活塞环切向弹力对机油消耗的4种模式的影响规律.结果表明,缸壁蒸发量主要由发动机运行工况决定;第2道环闭口间隙的增大会降低顶环开口窜油量和增大漏气量;活塞环弹力的增加会减小剩余油膜厚度,进而降低顶环甩油及活塞顶刮油量,但同时会增大活塞环与缸套之间的摩擦损失.最后进行了柴油机台架机油消耗量实验,一定程度上验证了仿真计算结果的正确性.

Simulation of Oil Consumption in Diesel Engine Cylinder and Analysis of Affecting Factors

In order to reduce the lubrication consumption of the engines, four main modes of lubricating oil con- sumption in cylinder are first analyzed and then the oil consumption rates under common working conditions are cal- culated for the four modes based on an engine. The result shows that most of the lubricating oil consumption derives from the evaporation of liner surface. Furthermore, the factors that influence the lubricating oil consumption such as working conditions, the second ring closed gaps, the elastic forces of the piston rings are also investigated for the four modes. Three findings are demonstrated. Firstly, the oil evaporation from the liner is determined by the working condition of the engine. Secondly, the increase of the ring closed gap reduces the oil blow through the top ring end gap and increases blow-by. Thirdly, the increase of the elastic force of the ring reduces the left oil film thickness, and the oil throw off at the top ring and the oil scraping of piston top edge are consequently decreased while the fric- tion loss between the rings and the liner is increased. In the end, the measurement of oil consumption based on ex- periment partly provides the validity of the simulation results.