轿车轮毂轴承实际工况下的弹流脂润滑数值分析

Numerical Analysis of Grease Elastohydrodynamic Lubrication of Automotive Wheel Hub Bearing Under Actual Working Conditions

轿车轮毂轴承实际工况下的脂润滑因基础黏度大、非牛顿特性强烈、当量接触曲率半径小,其弹性流体动力润滑计算有很大困难.文中在推导脂润滑弹流润滑计算基本方程的基础上,对方程进行了无量纲化和差分求解,求得轮毂轴承脂润滑弹流润滑的数值解,得到了润滑膜的压力分布和膜厚形状.结果表明:轮毂轴承脂润滑弹流润滑膜具有与油润滑类似的二次压力峰和出口膜厚颈缩现象;较小的载荷、较高的速度或较大的流变指数会形成较厚的润滑膜,相应的二次压力峰也更加明显;滚珠与滚道间的润滑实际处于弹流润滑和边界润滑交替变换的状态.

Due to the high initial viscosity,obvious non-Newtonian property and small equivalent radius in the grease lubrication of automotive wheel hub bearing under actual working conditions,great difficulties arise in the corresponding elastohydrodynamic lubrication （EHL）calculation.In order to solve this problem,basic grease lu-brication equations are derived,non-dimensionalized and difference-solved sequentially.After that,the numerical solutions of EHL of greased and lubricated wheel hub bearing,such as the pressure distribution and the thickness shape of lubrication film,are obtained.The results show that （1 ）in greased and lubricated wheel hub bearings, there exist a second pressure peak and thickness necking similar to those under oil lubricated condition;（2）light load,high velocity and large rheological exponent all help to form thicker lubrication film with a more obvious se-cond pressure peak;and （3 ）the lubrication between the rolling ball and the rolling cave is actually in an alternate state of EHL and boundary lubrication.