Analysis And Experimental Research On Vibration And Noise Of 6AT Transmission

Transmission is the key component of automobile transmission system.The dynamic performance of the gear transmission system inside the transmission will seriously affect the vibration and noise of the vehicle.Transmission is the transmission device of traditional fuel vehicle.The vibration and noise generated in the running process are transmitted to the vehicle through the body structure,which affects the sound quality of the whole vehicle.With the improvement of people’s requirements for vehicle quality,many automobile enterprises devote themselves to research and design low-noise transmission with the goal of improving vehicle quality and ride comfort,so it is very important to study the vibration and noise reduction of automobile transmission.This paper takes 6AT transmission as the research object,aiming at the problem of vibration and noise generated by transmission during operation,a research method is adopted to evaluate transmission noise from steady dynamic response to acoustic radiation calculation.The main research contents are as follows:Firstly,the generation mechanism and transmission path of transmission noise are analyzed,and the dynamic excitation finally acts on the housing to generate radiated noise.Using the multi-body dynamics method,according to the working principle of6 AT transmission In Lab software,a multi-body dynamic model of transmission system of the transmission including gear shaft,front planetary gear train,rear Ravina planetary gear train and reduction gear mechanism is established,the dynamic reaction force at each bearing seat is obtained,and the dynamic response characteristics of the system under different working conditions are studied.Secondly,Modal solution is used to analyze the 6AT transmission case,and the relationship between the gear meshing frequency and the natural frequency of the case is compared and analyzed.When the speed is 4000 rpm,the meshing frequency of the first reduction gear 2300 Hz under the 3rd gear working condition and the meshing frequency of the second reduction gear 1640 Hz under the 6th gear working condition are close to the fifth order natural frequency and the third order natural frequency of the housing respectively.With the dynamic response at the bearing as the excitation source,the vibration response analysis of the housing is carried out.When the gear meshing frequency is close to the natural frequency of the housing,the housing will resonate,and the vibration generated on the surface of the first reduction housing is more obvious than that of the second reduction housing.Therefore,the distribution of the radiated noise of the speed converter housing is predicted.Thirdly,based on LMS Virtual The Lab Acoustic module has established the acoustic boundary element model of the transmission case.With the vibration response data as the boundary condition,the radiated noise characteristics of the transmission in the external acoustic field are obtained based on the boundary element method.The peak values of the sound pressure level and sound power level appear at the first reduction gear meshing frequency of 2300 Hz,the second reduction gear meshing frequency of 1640 Hz and the octave frequency.The radiated noise is mainly distributed on the surface of the first reduction gear and the second reduction gear.According to the radiated noise characteristics of the transmission,the contribution of the acoustic panel of the transmission housing is analyzed.According to the calculation results of the contribution of the acoustic panel,the position of the first reduction housing is determined as the main noise source.Finally,on the basis of the above analysis of the radiated noise characteristics of6 AT transmission,the vibration and noise reduction of the transmission are studied.The comprehensive optimization method of gear modification and sound absorbing material sticking on the surface of the casing is adopted.The vibration and noise experiment of the 6AT transmission is carried out in combination with the optimization scheme.Compared with before optimization,the whistling noise level of the transmission is improved to a certain extent,and the noise is reduced by 2.32 d B and2.52 d B respectively in the third gear and sixth gear working conditions,it is confirmed that the previous simulation results are correct and the optimization scheme of vibration and noise reduction is feasible.