考虑非稳态传热的高速汽油机主轴承润滑分析

Lubrication Analysis of Main Bearing for High Speed Gasoline Engine Based on Non-stationary Heat Transfer

针对一款高速汽油机主轴承内部润滑与摩擦磨损问题,考虑到轴承承载不均导致的轴瓦与润滑油非稳态传热,基于弹性流体动力润滑(EHD)和轴承动力学理论方法,通过迭代计算,得出该高速汽油机具有代表性的第三主轴承在最大转速(9 500r/min)时轴承内部精确的温度场与热变形,并以此为轴承新的几何轮廓边界条件分析轴承的实际润滑情况。结果表明,与未考虑轴瓦温度场及热变形相比,轴承润滑状态明显恶化,具体表现为轴承最小油膜厚度减小、最大油膜压力增大,且出现较严重的磨损。最后通过发动机台架试验测得轴承的实际工作情况,并与计算结果进行对比,计算结果与实际摩擦磨损情况吻合,验证了所用方法和所得研究结论的正确性。

In order to solve the lubrication and wear problems of main bearing of a high speed gasoline engine ,the non-station-ary heat transfer of bearing bush and lube oil due to the uneven bearing was first taken into account .Based on the theory of e-lastic hydrodynamic lubrication and bearing dynamic ,the internal temperature field and thermal distortion of the third bearing at engine speed of 9500 r/min were obtained by iterative computation .The actual lubrication of bearing was analyzed according to the determined geometry contour boundary .The results show that the actual lubrication state is worse obviously when taking bushing temperature field and thermal distortion into account .The minimum oil film thickness decreases ,the maximum oil film pressure increases and the severe wear occurs .Finally ,the actual state of bearing is measured through the bench test and com-pared with the calculated results .The test and calculated results agree well ,which verifies the feasibility of the analysis method .