Evaluation,Analysis And Optimization Of Automotive Powertrain Vibration Isolation System

The design of powertrain vibration isolation system has an important influence on the performance of NVH.The hybrid vehicle vibration isolation system needed to be improved with the development of hybrid vehicles.This paper has done the following analysis and design:Firstly,the evaluation index of the powertrain vibration isolation system is studied and based on it,a powertrain mounting system model is established which included rubber suspension and hydraulic suspension.The main evaluation indexes of the powertrain vibration isolation system include the natural frequency of the powertrain mounting system,the modal decoupling rate index,the suspended vibration transmission rate index and the suspension system displacement control.Secondly,the test of vibration isolation ratio is the method of evaluating the powertrain evaluation index in experiment.But more attention is paid to the natural frequency and modal decoupling rate in the simulation design.This paper presents optimization design method of powertrain mounting system with displacement(force)transfer rate target,natural frequency and modal decoupling rate constraint.Particle swarm optimization(PSO)algorithm is used to establish different evaluation indexes in this paper.The optimization method is applied to rubber suspension and hydraulic suspension system.The vibration isolation performance of each optimization design method is compared and analyzed.Modal decoupling rate of strengthening the frequency of the vibration isolation design method,all aspects are more reasonable and effective.In order to improve the vibration isolation performance,this paper establishes a two-stage vibration isolation model of the powertrain-subframe and analyzes the influence of the subframe,that transmits the force of the powertrain to the foundation.The results show that adding the subframe can obviously improve the vibration isolation.The optimal design idea of the single layer model is applied to the two-layer model,and the constraints of the natural frequency of the subframe are added to obtain the optimization result.The modal decoupling rate of the powertrain in the two-layer model is improved,performance.Finally,it is found that there are obvious time domain vibration problems when the hybrid powertrain is started.The way to improve the problem is to change the three suspension to four suspension.The effectiveness of the proposed optimization method is verified by the different working modes of the hybrid powertrain,that is,the response of suspension points before and after optimization in different working modes is calculated.The results show that the optimal response time can be obtained result.It is proved that the optimization design method proposed in this paper can be combined with the experimental practice,which can guide the design of different powertrain vibration isolation.