Optimization Design Of The Mounting System Based On Vibration And Noise Control Of Vehicle Level

With the continuous improvement of customer comfort requirements and the use of high-power engines,the effective control of engine vibration transmission to the body,to improve the vehicle NVH performance plays a vital role.The mounting system,as the vibration isolation device of engine and body,needs further study to obtain the ideal vibration isolation performance.In this thesis,the function and design requirements of the mounting system are described and analyzed.Then,the calculation formula of powertrain excitation is deduced,and considering the influence of suspension and tire,the whole vehicle dynamics model of 13 degrees of freedom is established.The effect of vibration characteristics of the powertrain mounting system on vibration isolation is expounded.Finally,a design method of the mounting system satisfying the transfer characteristics is proposed from the viewpoint of the transmission characteristics of the mounting.This method takes the mounting stiffness as design variables,the natural frequency and decoupling rate as the constraint conditions,mounting force as the objective function to meet the transmission characteristics,and ultimately achieve the target vehicle response minimum goal,for the control of vehicle vibration noise mounting system design provides a theoretical and technical support is based on some theoretical significance and engineering value.Through the optimization design case of a car mounting system,the process and method of the mounting system design in the early stage of product development are introduced.Firstly,the traditional mounting system method is adopted to design,and then the whole vehicle target response is calculated through the vehicle finite element model with powertrain mounting system and the powertrain excitation.According to the analysis of the mounting transmission characteristics of the response peak,the design optimization direction of the mounting system is obtained.In the optimization design process of mounting system,the weight coefficient of mounting reaction force optimization is determined by the contribution of mounting transmission.With the natural frequency and decoupling rate as constraint.By optimizing the mounting stiffness,the mounting reaction force is obtained to meet the vehicle response.Finally,in order to evaluate the design effect of the mounting system in the early stage of product development,the performance of the mounting system is tested byusing a prototype vehicle,and the effectiveness of the proposed design method is proved.In the process of the performance test of the mounting system,the test procedure and method of the required equipment and common working conditions are described.The test results are evaluated,and the comparison between the test results and the simulation results is given.