不同曲轴平衡率下柴油机主轴承润滑特性分析及变壁厚优化设计

Lubrication Characteristics Analysis and Variable Wall Thickness Optimization Design of a Diesel Engine Main Bearing Under Different Crankshaft Balance Ratios

基于弹性流体动压润滑及多体动力学理论,以某船用大功率柴油机主轴承为研究对象,考虑曲轴主轴承的弹性变形、表面粗糙度、供油特性等因素,建立主轴承的弹性液体动力学仿真分析模型;通过试验对该模型建立方法进行了验证。基于该模型,分析了曲轴平衡率对主轴承最小油膜厚度、最大油膜压力、轴心轨迹及滑油填充率等润滑特性参数的影响规律,并就主轴承边缘接触压力较大的现象进行了变壁厚设计优化。研究表明:曲轴平衡率从0增大到100%,主轴承最大油膜压力平均值减小60%,最小油膜厚度平均值增大5倍,轴心轨迹偏心率减小;通过变壁厚优化设计,主轴承最小油膜厚度最小值增大24%,最大粗糙接触压力减小40%,粗糙边缘承载较大的现象得到有效改善。

Based on the theory of elastohydrodynamic lubrication and multi-body dynamics,the elasto-hydrodynamics lubrication model of the main bearing in a high-power marine diesel engine was established,and the elastic deformation,surface roughness,oil supply characteristics of the main bearing were considered.The method of establishing this lubrication model was verified by experiments.Based on this model,the influence of the crankshaft balance rate on the lubrication performance of the main bearing's minimum oil film thickness,maximum oil film pressure,shaft trajectory,and oil filling rate was analyzed.And the change of the bearing profiles was carried out to reduce the contact pressure on the bearing edge.The results showed that with the increase of the balance rate from 0 to 100%,the average maximum oil film pressure of main bearing decreased by 60%,and the average minimum oil film thickness increased by 5 times,and the eccentricity of axis track decreased.Through the optimized design of the bearing bush,the minimum oil film thickness of main bearing increased by 24%,and the maximum rough contact pressure decreased by 40%,which reduced edge wear.