曲轴轴向运动对粗糙表面曲轴主轴承润滑性能影响的研究

内燃机实际工作中，在多种影响因素综合影响下，曲轴进行旋转运动的同时，还存在沿轴承轴线方向的运动. 以某四缸四冲程内燃机曲轴-轴承系统为研究对象，综合考虑曲轴轴向运动、曲轴变形和摩擦表面粗糙度，基于平均Reynolds方程，建立了耦合曲轴轴向运动的粗糙表面主轴承润滑分析模型，着重研究了倾斜曲轴轴向运动对主轴承润滑特性的影响. 分析中，采用试验法实测曲轴沿轴承轴线方向的运动规律，应用有限单元法求解曲轴受载变形导致轴颈在轴承孔中倾斜状况. 结果表明:曲轴轴向运动对粗糙表面内燃机主轴承润滑特性影响显著；计及曲轴轴向运动时内燃机各主轴承轴颈轴心轨迹均为1条不封闭的三维空间曲线；曲轴轴向运动对主轴承润滑特性的影响程度与摩擦表面粗糙度直接相关；计及曲轴轴向运动时摩擦表面粗糙度对主轴承润滑特性影响趋势及程度均发生明显变化. 

Influence of Axial Motion of Crankshaft on Lubrication Performance of Rough Crankshaft Main Bearing

Under the combined influence of various influencing factors, the crankshaft will have axial motion along the axis direction of main bearings while it rotates in the actual operation of an IC engine. Taking the crankshaft-bearing system of a four-cylinder four-stroke IC engine as the research object, considering the axial motion, crankshaft deformation and surface roughness, a new lubrication model of the crankshaft main bearing was established based on the average Reynolds equation. The influence of axial motion of crankshaft on lubrication performance of crankshaft main bearing was studied. In the analysis, the motion law of the crankshaft along the bearing axis was measured by the test method, and the finite element method was applied to solve the tilting of the crankshaft in the bearing bore caused by the crankshaft deformation. The results show that the axial motion of crankshaft had a significant influence on lubrication of crankshaft main bearing with a rough surface. The journal center trajectory of main bearing was an unclosed three-dimensional space curve when the axial motion of crankshaft was taken into account. The degree of influence of the axial motion of crankshaft on the lubrication characteristics of the main bearing was directly related to the surface roughness. The influence trend and degree of the surface roughness on the lubrication characteristics of main bearing were obviously changed when considering the axial motion of crankshaft.