曲轴平衡块配置对曲轴动力润滑特性影响的仿真研究

A Simulation Investigation of Effect of Counterweight Configurations on Dynamical Behavior and Lubrication Characteristics of Crankshaft Systems

基于多体动力学与弹性流体动力润滑理论,在考虑内燃机轴瓦与轴承座的弹性变形、轴瓦与轴颈粗糙度的基础上,建立了四缸柴油机主轴承仿真模型,研究了四缸机曲轴不同平衡块配置方案对主轴动力学与润滑特性的影响.研究结果表明:随着平衡率增加,MB1(第一)、MB3(第三)、MB5(第五)主轴承最大载荷增加,平均轴承载荷减小,MB5的最大弯矩、平均弯矩相比较大,容易出现偏磨现象;随着平衡率增加,MB5的最小油膜厚度减小,平均油膜厚度增加,主轴承的峰值油膜压力平均值减小,总摩擦功耗减小,轴承端泄流量减小;平衡率相同时,曲轴采用四块或八块平衡块对轴承载荷及润滑特性影响较小,四块平衡块的曲轴相比八块平衡块,MB1、MB3、MB5最大弯矩平均小5%,平均弯矩平均大2%,MB5轴承平均端泄量平均增加4%.

By considering the elastic deformation of bearings and bearing houses in engine and the roughness of bearings and journal, a main bearings＇ simulation model of a 4 - cylinder diesel engine is established, based on multi body dynamic and elastohydrodynamic （EHD） lubrication theory. The effect of counterweight configurations on dynamical behavior and lubrication characteristics of crankshaft systems is researched. The result indicates that maximum bearing forces at main bearing 1 （ short for MB1 ） , MB3 and MB5 increase, while average bearing forces at these bearings decrease. In addition, maximum and average bearing moments at MB5 are relative bigger than other beatings so that it could be easily to cause partial wear. As the balancing rate increases, minimum oil film thickness at MB5 decreases, but average oil film thickness at MB5 increases, average peak oil film pres- sure, total friction power losses and oil outflow at MB5 all reduces. Crankshafts with 4 counterweights or 8 coun- terweights have few differences in bearing forces and lubrication characteristics. Compared with crankshaft with 8 counterweights, maximum bearing moments at MB1, MB3 and MB5 are 5% less, average bearing moments at these bearings are 2% more, while average oil outflow at MB5 increases 4% in crankshaft with 4 counterweights