Research And Optimization Of Torsional Vibration Characteristics Of FR Automobile Powertrain

In recent years,the market of multi-purpose vehicle(MPV)has been booming,followed by the vibration and noise problems caused by the lightweight structure of multi-purpose vehicles and the large power engines.As people's requirements for comfort are becoming higher and higher,the related laws and regulations on vibration and noise issued by the state are becoming stricter and stricter.Therefore,it is very necessary to further research the problem of vibration and noise reduction of multi-purpose vehicles.At present,a multipurpose vehicle has the problem of vibration and noise,which affects the service life of components and ride comfort.This paper takes the powertrain of a FR MPV as the research object.In view of the torsional vibration problem of the object,this paper researches the torsional vibration characteristics and the optimization measures of the powertrain.Finally,the comprehensive optimization measure considering both of the torsional vibration of the powertrain and the power performance of the automobile is proposed.The main research contents are as follows:Firstly,the mechanism of the booming noise in the vehicle caused by the torsional vibration of the powertrain has been studied through experimental tests.These experiments include vibration and noise test,the powertrain torsional vibration test,coherent analysis test of vibration signal and noise signal and the transmission path analysis test.These experimental tests find out the reason why the booming noise in the vehicle is generated and also provide comparable experimental data for subsequent modeling.Secondly,the torsional vibration equivalent model of the powertrain has been established.The free vibration model has been established and the modal frequencies and modal shapes of the system have been calculated.Then the forced vibration model has been established and the torsional vibration response of the system has been calculated.The accuracy of the model is verified by comparison between simulation calculation data and experimental test data.The establishment of the torsional vibration model provides the basis for the further analysis of torsional vibration characteristics and optimization measures.Thirdly,the torsional vibration characteristics of the powertrain have been studied and the torsional vibration optimization measures have been proposed.On the base of the torsional vibration model of the powertrain,the influence of the parameters of the powertrain on the torsional vibration characteristics has been obtained through the sensitivity analysis,and the key parameters which have great influence are found out.Then,based on the idea of multiobjective optimization method,the genetic algorithm is used to optimize the torsional vibration problem,and some torsional vibration optimization measures such as optimization of the parameters of the powertrain,the installation of the dual-mass flywheel and torsional vibration damper are proposed.Finally,a comprehensive optimization measure for torsional vibration considering the vehicle power performance has been proposed.The indexes of power performance before and after the implementation of the torsional vibration optimization measures have been calculated and compared,and whether the proposed torsional vibration optimization measures will have an impact on the vehicle power performance have been researched.It was found that adjusting the main reduction ratio has a great influence on the vehicle power performance,therefore the gearbox transmission ratio should be adjusted at the same time.Finally,a comprehensive optimization measure of torsional vibration including installing the dual-mass flywheel and adjusting the transmission ratio was proposed.In summary,this paper has found out the reason of the booming noise in the vehicle through experiments,established the equivalent model of the powertrain,analyzed the torsional vibration characteristics of the powertrain and proposed some torsional vibration optimization measures,studied the influence of the torsional vibration optimization measures on the power performance of the vehicle,and put forward a comprehensive optimization measure of torsional vibration considering the power performance of the vehicle.The above work can not only directly conduct the rectification of object vehicle,but also provide reference to analyze and solve the similar problems.