Vibration And Noise Prediction And Optimization Analysis Of A Passenger Car Transmission

In the automobile transmission system,the automobile gearbox is a very important part,only to ensure the good performance of the automobile gearbox can guarantee the performance of the whole vehicle.From the perspective of the transmission system as a whole,the working environment of the gearbox is very demanding for the gears.If the gears work in a bad environment for a long time,it will inevitably lead to the noise and vibration of the gearbox.Now,people’s requirements for the car have changed,for the car quality requirements are getting higher and higher,so the car work noise has become the key concern of each car company.In this paper,a model of transmission as the research object,by collating a lot of about the development status and trend of transmission research both at home and abroad literature,analyzed the cause of vibration,also focuses on the interior of the gear system,including the stiffness excitation,error excitation and meshing shock excitation,analysis the main gearbox under transmission error excitation vibration noise characteristics.The dynamic model of gear transmission system was established,and the multi-body dynamic analysis was carried out to analyze the transmission error in the third gear and sixth gear working conditions.The rotational speed was 3000r/min and the torque was 260 N﹒m under the working conditions.The bearing dynamic force under the transmission error is obtained.The finite element mesh of the geometric gearbox is divided,the finite element model of the gearbox is obtained,and the modal analysis under the constraint state is carried out to simulate the real working state of the gearbox,the natural frequency and mode of vibration under each mode are analyzed,and the parts of the shell that are prone to vibration are determined.Conclusion by multi-body dynamics to solve the dynamic force bearing under different working conditions,in order to get the bearing dynamic force as boundary conditions,the vibration response of shell finite element model is imported into the gearbox,through LMS Virtual Lab software based on the modal superposition method to analyze vibration response of transmission box,the vibration acceleration response on the surface of the finite element model to calculate the transmission box,and vibration acceleration nephogram and test points of vibration acceleration spectrum.Its acoustic boundary element model based on casing finite element model,using the vibration acceleration response on the surface of body gets as boundary conditions,through the rule of mapping data mapping to the boundary element model,using the method of modal acoustic transmission gearbox shell for radiation noise analysis,analysis of gearbox shell radiation sound power level and the sites of sound pressure level.By analyzing the modal participation factor and modal acoustic contribution of the gearbox housing,the modal order which contributes more to the vibration and acoustic contribution of the housing is obtained.By optimizing the shell structure and comparing the vibration characteristics and radiated noise of the gearbox shell before and after the optimization,the scheme has obvious effect on reducing the vibration noise of the shell.