Research And Optimum Design Of Vibration Isolation For Power Assembly Mounting System Of Electric Vehicle

With the energy crisis is becoming more and more serious in today's Society,the research and development of new energy vehicles has attracted more and more attention?Pure electric vehicles have the advantages of simple structure,low noise and no emission pollution,which become a trend in the automotive industry research and development,and have broad prospects for development in the future?The main vibration source of pure electric vehicle comes from the excitation of powertrain and road surface?As an important component to isolate and attenuate the vibration of powertrain,mounting system plays a very important role in improving the NVH performance of the vehicle?Therefore,the vibration analysis and optimization design of powertrain mounting system is an important link to improve and improve the NVH performance of the vehicle,which has certain engineering practical significance?Based on the NVH performance improvement project of a company's SUV pure electric vehicle,this paper studies a pure electric vehicle,aiming at the obvious increase of vibration when the steering wheel and seat guide rail are in the position of 1000-2500 RPM in the cab during acceleration test?The method of combining analysis and investigation,order analysis,modeling and simulation with experimental verification is used to find the source of the problem,and the optimization and rectification scheme is put forward?Firstly,in the semi-anechoic test room of the whole vehicle,the vibration test of the prototype car under accelerated working conditions is carried out?Through investigation and analysis,it is determined that the excessive vibration response of the cab is caused by the vibration generated by the motor transmitted through the structure?Secondly,through the vibration isolation performance test of the powertrain mounting system,it is found that the mounting elements of the powertrain have not played an ideal attenuation effect on the vibration of the active end of the powertrain within the working range of the powertrain,and the vibration isolation performance of the powertrain mounting system can not meet the requirements,so the performance analysis and improvement design of the powertrain mounting system are needed?Thirdly,based on the theory of multi-body dynamics ADAMS software modeling,the three-dimensional model of power assembly built by Catia software is imported into ADAMS through transformation,and then the virtual prototype simulation model is built?Through the frequency domain simulation analysis of the mounting system,the modal frequencies and the energy coupling distribution in six directions of the powertrain mounting system are obtained?Then,the force of the mounting element in Z direction and the displacement of the centroid of the powertrain along X,Y and Z directions are simulated and analyzed in time domain when starting and turning under typical working conditions,and the two typical mounting systems are obtained?Transient response characteristics under operating conditions?Fourthly,through experiment and simulation,combining the characteristics of pure electric vehicle?Taking the stiffness of the suspension as a variable,ADAMS and Isight software are integrated to simulate and optimize the suspension system.The energy decoupling rate of the suspension system is improved,the natural frequency of the suspension system is rationally allocated,the vibration energy of the passive end of the suspension system is reduced,and the performance of the suspension system of the test prototype vehicle is optimized and improved.Then the optimized results are imported into ADAMS for simulation and comparative analysis?Referring to the North American 28 working conditions load calculation code of power assembly,15 typical working conditions of pure electric vehicle are formulated?The working conditions load simulation is carried out by ADAMS,and the displacement and force values of the transient response of the mounting system are obtained?The non-linear stiffness design of the mounting is completed by using displacement control method,and simulated by software?Find out the corresponding curve?Finally,the suspension sample is trial-produced according to the optimized target value,and the experimental verification proves that the vibration isolation performance of the improved suspension system has been greatly improved,and the effectiveness of the optimization scheme has been determined.