脂润滑轮毂轴承弹流润滑数值分析

Numerical Analysis on Elastohydrodynamic Lubrication of Automotive Wheel Bearings Lubricated with Grease

基于Ostwald模型建立脂润滑控制方程,运用多重网格法求得等温线接触脂润滑弹性流体动力润滑数值解,得到钢球-沟道的压力分布、油膜形状及最小油膜厚度。针对轿车轮毂轴承的典型应用工况条件,分析工况参数对油膜压力分布和油膜形状的影响。结果表明:脂润滑弹流膜具有与油润滑膜相同的二次压力峰和出口颈缩现象。在轿车轮毂轴承可能的承载条件下,随着载荷的减小,二次压力峰的高度降低,其位置向入口区移动;一定承载条件下,速度增加时,膜厚相应增加,油膜的平行部分缩短,二次压力峰的高度增加,其位置也向入口区移动;一定承载和卷吸速度下,润滑脂流变参数增大时,二次压力峰的高度升高,其位置向入口区移动,膜厚相应增加。

The constitutive equation of grease lubrication based on the Ostwald model was established and the numerical solution of isothermal line contact grease elastohydrodynamic lubrication was calculated with multiple - grid method. Oil film shape, pressure distribution and minimum film thickness of ball-channel were obtained. Effect of parameters on lubrication film shape and pressure distribution was analyzed for the typical working conditions of automotive wheel bearings. Results show that grease elastohydrodynamic lubrication film possesses the same pressure spikes and outlet necking phenomenon as the oil elastohydrodynamic lubrication film. Under the bearing conditions of automotive wheel bearings, the height of pressure spikes reduces with the increase of load,and its location shifts to the entrance. Under certain load, the film thichness and the height of pressure spikes increase with the increase of speed, and the location of pressure spikes shifts to the entrance. Under certain load and entrainment velocity, the height of pressure spikes and the film thichness increase with the increase of grease rheological parameter,and the location of pressure spikes shifts to the entrance.