Analysis And Improvement Measures Of Vibration And Noise For Automobile Drive Axle

The problem of automotive vibration&noise is a comprehensive problem to measure the manufacturing quality of the automobile.According to statistics,automobile manufacturers invest 20%of R&D funds to solve the problem of the automotive vibration&noise.As one of the automobiles vibration&noise sources,the drive axle has a great influence on the automobile NVH performance.Therefore,it’s of great significance to study the vibration&noise of the automobiles drive axle.In this paper,the research methods and improvement measures for the drive axle’s vibration&noise are valuable for the analysis of other components’vibration&noise.The study of this paper are as follows:Firstly,the transmission of vibration&noise excitation and the radiation noise of the drive axle were analyzed.The final reducer gear pair was simplified to a single degree of freedom vibration model.Then,transmission error excitation,meshing stiffness excitation and meshing impact excitation were analyzed.On the basis of Helmholtz theory,the surface of the drive axle was discretized by the boundary element method.The sound pressure,sound intensity and sound power in the radiation noise field were predicted.This part is the theoretical basis of simulation analysis.Secondly,the finite element model was established,and the modal of the drive axle was analyzed.After establishing a finite element model of the drive axle,the finite model calculation method was used to analyze the modal of the drive axle.Then,the modal of the drive axle was analyzed by modal test.The modal calculation results and test results were compared and analyzed.The study found that they were consistent,which verified the correctness of the finite element modal.Then,the drive axle vibration was studied,and the radiation noise was predicted.The drive axle vibration at the constant speed of 80km/h and 120km/h was simulated.The study found:the final gear meshing excitation is pulsed excitation;the drive axle vibration is periodic;the Z-axis vibration of the axle housing rear cover is the most severe of the drive axle;the vibration of the drive axle at 120km/h is more severe than 80km/h.Then,the boundary element method was used to simulate the radiated noise of the drive axle.By analyzing the sound pressure cloud diagram and the sound pressure level time domain map,it was found that the radiated noise of the drive axle was centered on the rear cover of the axle housing which spread radially outward.The sound pressure level at the 120km/h was about 6dB higher than the 80km/h.Next,the vibration&noise of the drive axle was studied through tests.The vibration and noise bench test program was referred to QC/T 533-1999.Because the bench test results were consistent with the simulation result,the correctness of the simulation method was proved.The road test studied the vibration&noise of the drive axle in the acceleration and gliding conditions of the 4^th and 5^th gear.The analysis results show:when the input shaft speed of 4^th gear was 2700rpm,the drive axle resonated.Finally,the improvement measures of vibration reduction and noise reduction were proposed.In view of the problem conditions,this paper proposed to install damping dynamic damper for the drive axle and spray 2mm waterborne damping coating on the axle housing surface.The simulation analysis method was used to analyze the vibration&noise reduction effects.The results show that the improvement measures can reduce the vibration of the drive axle by 40%and reduce the noise sound pressure level by 2.88dB.