Finite Element Analysis And Lightweight Design Of Coaxial Integrated Electric Rear Axle For Electrical Vehicle

The pure electric vehicle has been paid more and more attention by the country for its low noise,no pollution,clean energy and low emission.As an important branch of the pure electric vehicles,electric business vehicles can be widely used in many fields,such as electric logistics vehicles,electric light truck and so on.However,with the market demand for electric business vehicles increasing,its problems have been presented in reality,of which the integration of rear axle is particularly serious.As the main bearing and transmitting part,not only rear axle needs an integrated structure to minimize the volume for arranging electric car battery easily,but also it needs a higher carrying capacity to meet the demand of goods for electric vehicle.Therefore,it is important to design a kind of electric rear axle to meet the above requirements for electric business vehicles.This paper proposes a novel coaxial integrated electrical rear axle system relied on a Chongqing Automobile Co.,Ltd.funded project ——the research on electric vehicle rear axle system And its strength,stiffness,fatigue life are analyzed and its structural lightweight optimization is studied.Firstly,the existing structure of electric vehicle rear axle is analyzed and based on the existing structure,a coaxial integrated electrical rear axle system is proposed.Then the parameters of the driving motor and transmission system are matched based the new configuration of electrical rear axle and the actual vehicle parameters.Finally,the 3D geometric model of the electrical drive rear axle is constructed.Secondly,the finite element model is established based on the geometric model of coaxial integrated electrical rear axle.The loading and constraint conditions of electrical rear axle under the four limited driving condition are studied.The strength,stiffness of electrical rear axle are simulated under the four limited driving condition based on ANSYS Workbench simulation platform.Thirdly,with the consideration of electric rear axle house material characteristics and its actual processing method,S-N of the material were revised.Then the fatigue life of rear axle house analysis and fatigue safety coefficient distribution analysis are carried based on the modified S-N curve.The modal analysis of the integrated electrical drive rear axle is carried out,and the natural frequency of 1-6 is obtained,which is compared with the actual operating frequency to avoid the resonance failure.Finally the structure of the rear axle promotes according to the simulation results of the strength,stiffness and fatigue life.Fourthly,Lightweight optimization model of electrical drive rear axle is constructed,which regards rear axle sleeve thickness and the middle axle house thickness as variables,the maximum displacement and maximum stress of rear axle as constraint conditions,the total rear axle house quality as the objective function.The goal-driven optimization scheme is used to solve the lightweight model and the response surface relationship between each variable and constraint condition and objective function is determined.Finally,based on improved structure and lightweight design results,the sample of coaxial integrated electrical rear axle is completed.And the driving motor test system of rear axle is developed,on which the characteristic curve of the motor in electrical rear axle is tested and the running test of the rear axle system assembly is accomplished.