Analysis And Optimization On Riding Comfort Of Three-axle In-wheel Motor Vehicle

At present,the in-wheel motor is more and more used in wheeled vehicles,but the study found that the wheel motor increased the unsprung mass of the vehicle,so that its ride comfort significantly deteriorated.In this paper,the ride comfort analysis and optimization of a suspension system of a three-axle in-wheel motor vehicle are carried out.Firstly,a nine-degree-of-freedom vehicle vibration model is established.The vibration response of the vehicle body acceleration,the relative dynamic load of the wheel and the suspension displacement is analyzed and simulated to evaluate its ride comfort.Then,the parameters of unsprung mass are analyzed.The results show that the mean square root of the relative dynamic load of the wheel increases sharply with the increase of the unsprung mass;the root mean square of the vertical acceleration of the vehicle decreases a little;root mean square value of suspension displacement did not change significantly.The root mean square value of the vertical acceleration is optimized by the genetic algorithm toolbox in MATLAB/Simulink.The optimization results show that if the vertical acceleration of the vehicle changed from 0.8367m/s2 to 0.7767 m/s2,down by 7.2%;the first axle suspension displacement improved by 5%;the relative tire dynamic load of the first axle improved by 7%.After optimization the vehicle ride comfort has improved a lot.According to vehicle parameters and the requirements of suspension design,the design of single trailing arm independent suspension is completed.The position of each hard spot is determined by kinematics analysis,and then the vehicle force analysis is carried out.And the variable stiffness spring and the damper are designed.Based on the principle of topology optimization,ANSYS software is used to optimize the suspension structure.The optimization results show that the mass of the single wheel suspension system reduced by 20%,and the suspension strength is analyzed under three kinds of conditions,The maximum stress of the structure is 565MPa,which is smaller than the yield strength of 30CrMnSi,885MPa.The single trailing arm independent suspension engineering prototype and the corresponding test bench were designed,and the basic performance of the single trailing arm independent suspension was conducted by bench test.The test results show that the engineering prototype of single trailing arm independent suspension has reached the engineering design requirements.