Vibration Isolation Analysis Of Passenger Vehicle Powertrain Mount System And Optimization Design

With the development of automobile technology and the continuous progress of vehicle design level,the performance of automobile is also constantly improved.With the gradual improvement of road traffic conditions,the vibration of automobile engine has an increasingly obvious influence on the ride comfort of drivers and passengers.Therefore,improving the vibration isolation performance of the powertrain mounting system is particularly important to improve the ride comfort of the vehicle.First of all,the general research situation of the suspension system is described,and the main functions of the suspension system are introduced.After that,the theoretical and experimental research progress of the domestic and foreign people is described.The excitation force and torque of single cylinder crank connecting rod mechanism and four-cylinder engine are deduced,and the mathematical model of vibration isolation system is established to derive the kinetic energy,potential energy and dissipative energy of the system respectively.The position of the torque axis is calculated by using the torque axis decoupling method.Secondly,3d modeling is carried out on the powertrain mounting system through 3D modeling software CATIA,and the established model is imported into ADAMS.In ADAMS software,parametric modeling is carried out on the whole system,and appropriate simplification and constraints are carried out on the model,so that the mounting system has six degrees of freedom.Then the system is simulated to obtain the natural frequency of the system,the decoupling rate of each order,and the vertical transfer force of the mounting element.The position of the torque axis is calculated,and five sets of data are taken from the top and bottom of the theoretical position for simulation,so as to determine the actual position of the torque axis.The analysis results show that the decoupling rate of the fourth order rotation direction of the system around the Z-axis is too low,which should be optimized in the following paper.Thirdly,on the basis of the six degrees of freedom model of the suspension system,thirteen degrees of freedom of four wheels moving up and down and thirteen degrees of freedom of body roll,pitch,and up and down vibration are added,and the model is built.The dynamic simulation of the whole system is carried out under the whole vehicle model,and the response characteristics of the whole system in time domain and frequency domain are obtained by substituting the derived formula of engine excitation force and excitation torque.It can be seen from the results that in idle speed condition,the vibration is mainly second-order and peaks at the frequency domain as shown in FIG.25 HZ.Then,the vehicle vibration test was carried out,the measured data was collected and processed by LMS software,and the test data were compared with the simulation data.After comparison,it was found that both sets of data reached the vibration amplitude near the position of 25 HZ and the trend was basically the same,which proved the accuracy of the simulation model.Finally,Isight software was used to optimize the existing suspension system.The layout position and stiffness in each direction of the suspension components were taken as design variables,and the decoupling rate of each order of the system and the vertical support reaction force of the suspension components were taken as optimization objectives.According to the optimization results,the decoupling rates of each order reached more than 90%,the vertical transmission force at each position decreased,and the vibration isolation rate also increased significantly,reaching the optimization goal.