基于CFD方法的轮毂电驱动行星齿轮搅油功率损失仿真与分析

Simulation and Analysis of Oil Churning Power Loss in Electric Drive Planetary Gears Based on the CFD Method

轮毂电驱动技术的研究是未来新能源驱动体系研究的重要方向。随着轮毂电驱动对转速的要求越来越高,搅油功率损失成为不可忽略的部分,甚至高达功率总损失的50%~80%。现有的计算搅油损失的方法主要是采用简单的经验公式,无法适用于复杂的行星齿轮传动。为此,采用计算流体力学(Computational Fluid Dynamics,CFD)软件与C语言用户自定义函数(User Defined Function,UDF)对两级行星齿轮传动飞溅润滑进行联合仿真,实现了油-气两相瞬态流场可视化;通过提取表面的压力和黏性力,得到了太阳轮、行星轮及行星架的搅油损失;对25种工况进行仿真与分析,得到了搅油功率损失随转速和浸油深度的变化趋势。结果表明,搅油功率损失随转速和浸油深度的增加而增大,且无明显的拐点,实现最小搅油损失应当在保证充分润滑的前提下取最小的浸油深度。

The research on electric drive wheel technology is an important direction of the research on the new energy drive system in the future.With the increasing requirements of the electric drive wheel on the speed,the oil churning power loss has become a non-negligible part,even up to 50%-80%of the total power loss.The existing calculation method of churning loss mainly adopts simple empirical formula,which cannot be applied to complex planetary gear transmission.The splash lubrication of the two-stage planetary gear drive is simulated by computational fluid dynamics(CFD)software and C language user defined function(UDF),and the visualization of oil gas two-phase transient flow field is realized;by extracting the surface pressure and the viscous force,the churning loss of the sun gears,planet gears and planet carriers are obtained;the simulation and analysis of the 25 working conditions show that the churning loss varies with the immersion depth and speed;the results show that the oil churning power loss increases with the oil immersion depth and the speed,and there is no obvious inflection point.To achieve the minimum oil stirring loss,the minimum oil immersion depth should be taken on the premise of ensuring full lubrication.