Powertrain Torsional Vibration Of A Certain-FR MPV

The vehicle powertrain is a typical multiple degree-of-freedom torsional vibration system.The torsional vibration response of powertrain has an important influence on the NVH performance.It is of great significance to the design of power transmission system to predict the torsional vibration response,reduce vibration and noise through the establishment of a torsional vibration model and the optimization of relevant parameters.According to the problems of abnormal vibration and noise for the MPV in a 3rd gear WOT transient,experiments of vibration and noise under different working conditions were carried out to discuss the sources of abnormal vibration and noise with the combination of subjective evaluation.In order to investigate the influence of moment of inertia of flywheel on powertrain torsional vibration,the torsional vibration experiments were carried out in a second time by replacing flywheel with a large moment of inertia.The results show that the angular acceleration of the flywheel and the transmission input shaft have an important influence on the response of torsional vibration.The powertrain torsional vibration can be suppressed with the increase of moment of inertia of flywheel by 18%.In a 3rd gear WOT transient,the peak value of the angular acceleration of flywheel is reduced by 10% and the angular acceleration of the transmission input shaft is decreased by 8%.Based on the analysis of multibody system dynamics,with consideration of the structure of engine,clutch,transmission,drive shaft and drive axle,a torsional vibration model for a FR MPV was established to analyze the abnormal vibration and noise in a 3rd gear WOT transient.The dynamic simulation was carried out by using the measured cylinder pressure of the engine under a 3rd gear WOT transient and the accuracy of the model was verified by comparing the results with experiments.Based on the dynamic response of Powertrain,the angular acceleration of the flywheel,the transmission input shaft,drive shaft and half shaft are investigated,and the influence of flywheel inertia,clutch stiffness,clutch damping and half shaft torsional stiffness on powertrain torsional vibration have been discussed,which can provide theoretical support for the optimization of torsional vibration response for powertrain with the change of relevant parameters.The results show that the powertrain torsional vibration can be suppressed by increasing the flywheel inertia,clutch damping and half shaft torsional stiffness and decreasing the clutch stiffness.However,the optimization of the parameters should be combined with the actual conditions of vibration and noise due to the difference of the influence of each parameter on powertrain torsional vibration.