Study On Influence Of The Flexible Gear Of Main Reducer On Vibration Characteristic Of Vehicle

With the development of society and the progress of science and technology,the performance of automobile has been greatly improved,and people are paying more attention to the comfort of the MPV vehicle.Torsional vibration of driveline and body vibration are important research objects in the automotive NVH problem,and the main reducer is an important coupling way between the two.In order to study the influence of the gear flexibility of the main reducer on the vibration characteristics of the whole vehicle,this paper takes a post drive MPV vehicle as the research object,and studied the influence of the gear flexible body model of the main reducer on the vibration response of the whole vehicle,and compares the simulation results with the experimental test results.Through the analysis of the mechanism of the gear meshing impact force,the meshing force and impact force of the gear are calculated,and the relationship between the gear meshing impact force and the gear meshing force is studied.It is concluded that the meshing impact force is the main cause of the gear meshing force fluctuation.After comparing and analyzing with the rigid-body gear model simulation results and experimental test results,it is found that the rigid-body model simulation results are less accurate and less consistent with the experimental test results,and it is difficult to provide a reliable reference in automotive vibration noise control optimization.In order to verify the superiority and accuracy of the flexible body gear in the simulation calculation,a rigid body multi body dynamic model of the gear of the main reducer is set up,and the multi body dynamic model of the flexible body gear is established by the finite element method.The two models are simulated by dynamic simulation,and the meshing force of gear is calculated theoretically,and the three forces of gear meshing force are obtained respectively.The simulation results of the two models are compared with the theoretical calculation results.It is found that the three direction meshing force of the flexible somatic gear is closer to the theoretical calculation.And compared with the rigid body model,the rotational speed fluctuation of the flexible somatic gear is more in line with the true situation of the gear meshing rotation.The stiffness of the flexible body model was changed by adjusting the elastic modulus of the model,and the dynamic simulation results of the flexible body model with different stiffnesses were studied.It was found that the higher the stiffness,the smaller the fluctuation of the gear meshing force,which is consistent with the theoretical formula.Simplifying related components and establishing rigid body flexible coupling model for vehicle body dynamics including flexible main reducer gear.Through the vehicle vibration coupling theoretical model,it is verified again that the main reducer gear is an important way of coupling between torsional vibration and body vibration.Through the modal calculation of the flexible body,we get the vibration mode and vibration mode of the vehicle body,so as to prepare for the coupling vibration analysis of the transmission system and the car body.The forced vibration simulation of the whole vehicle vibration model including the flexible body gear was performed,and the vibration response at the same position as the actual measured measurement point was obtained.The simulation results were compared with the rigid body model simulation results and the experimental measurement results.The results showed in the whole vehicle vibration simulation which contains the flexible gear model,the vibration response amplitude and resonant speed of the actual test results are more consistent with the experimental test results.The effects of the stiffness of the rubber bushing and the stiffness of the coil spring on the acceleration response of the vehicle body were investigated.The dynamic vibration simulation was performed by changing the stiffness of the bushing and the coil spring.The results show that the damping scheme is correct and effective,and can provide reference for the Formulating of optimal control strategy for automotive vibration and noise problem.