Design And Experimental Research On Intermediate Support Of Automobile Transmission Shaft

Consumers’ cognition and requirements for the overall performance of automobiles are getting higher and higher,not only in the performance of power,braking,acceleration,etc.,but also in the performance of car noise,vibration and harshness(NVH),which has become one of the important considerations of current automobile buyers.Therefore,solving NVH problem of automobile is an important performance to provide automobile product quality.The drive shaft is the main part of the vehicle’s power transmission,which is responsible for transferring the power output from engine to gearbox to the rear axle drive wheel in the process of automobile running.However,due to the mechanical characteristics of the transmission shaft structure itself,and the working condition of high speed,the vibration phenomenon will inevitably appear,which will affect the NVH performance and ride comfort of the vehicle.In this paper,the vibration characteristics of a vehicle transmission shaft intermediate support and transmission system are studied.The main work of the paper is as follows:(1)The mechanical characteristics of the universal joint of the cross shaft are analyzed,and the force of the intermediate support in the transmission shaft is deduced.The resonance frequency with the vibration of the transmission shaft is avoided by changing the stiffness of the intermediate support.The finite element method is used to calculate the free modal frequency of the transmission shaft and convert it to the corresponding critical speed,and the value range of the stiffness K of the intermediate support is solved.(2)Dynamic simulation software ADAMS was used to establish the dynamic model of the drive shaft assembly,and the influence of single and double layer vibration isolation intermediate support on the vibration of the drive shaft was simulated and compared.Taking the stiffness of the intermediate support as the design variable and the minimum RMS value of the vibration acceleration of the intermediate support seat as the objective function,the dynamic model of the transmission shaft was simulated and optimized.The influence of the variation of the stiffness value of the intermediate support on the vibration of the transmission shaft is studied,and the optimal elastic stiffness value of the intermediate support is obtained.(3)Design the intermediate support structure,and then divide the intermediate support rubber parts through the pre-processing module of the finite element analysis software Hypermesh,and the complete finite element model is established by ABAQUS for the mesh model,and perform finite element simulation calculation and analysis;The static characteristics of the intermediate support samples were tested and compared with the static stiffness results obtained by simulation.(4)Through the vehicle vibration test,extract the vibration signals at the intermediate support and the rear axle housing,processing and analysis them.Compare the impact of the intermediate support stiffness of the transmission shaft on the vibration of the vehicle before and after optimization,and use the root-mean-square value of the vibration acceleration of the driving seat rail as the vibration evaluation index of the vehicle to evaluate the vibration performance of the test vehicle.