Analysis And Research On Vibration And Noise Characteristics Of Automobile Gearbox

As a load bearing device of power input and output,gearbox is indispensable in both traditional internal combustion engine vehicles and emerging new energy vehicles.Planetary gear transmission is widely used in gearbox because of its strong bearing capacity,high transmission efficiency and large transmission ratio.Gearbox noise is one of the main noise sources of antomobile,which has a great influence on the performance of noise and vibration(NVH).Therefore,the estimation and control of its radiated noise are paid close attention to by researchers.In this paper,the planetary gearbox carried by an electric vehicle is taken as the research object,By means of theoretical anslysis,numerical simulation,test and other means,a vibration and noise estimation method for the gearbox considering the flexibility of the box and the floating of the sun gear is proposed to estimate and optimize its vibration and noise performance at high speed.It provides a research idea to solve the NVH problem of gearbox.The mean research work of this paper includes:1)Dynamics analysis of rigid-flexible coupling of planetary gearbox.By exploring the meachanism of planetary gearbox,combining the finite element and multi-body dynamics method,considering the floating characteristics of the solar wheel and the flexibility of the box body,the rigid-flexible coupling dynamics model was established by using ADAMS to analyze the time-frequency characteristics of gear meshing force and bearing dynamic load.2)Vibration response analysis of gearbox based on mode superposition method.By establishing the finite element model of the system considering the action of the motor,the inherent vibration characteristics of the gearbox are analyzed.By applying the bearing excitation force to the finite element model and using the modal superposition method to obtain the vibration data of it,it is found that the internal flexible structure and the outer end face of the planetary frame are the weak parts of vibration.3)Estimation of radiated noise from planetary gearboxes.Taking the vibration velocity of the outer suface as the input condition,an IBEM was used to establish the prediction model of the radiation noise of the box.At the same time,acoustic transfer vector method was used to further study the acoustic contribution of the cabinert panel,it is found that the structure of planetary frame,inner ring and large gear contribute much to noise.4)Multi-working condition analysis and structure optimization of gearbox.Based on the study of the influence of rotating speed and load changing conditions on the vibration noise of the gearbox,it is shown that the fluctuation of rotating speed will lead to the increase of the side band component of the gear meshing frequency and increase the radiation noise.The amplitude of full frequency band is affected by load variation.At the same time,according to the above results,the optimized design of the box was carried out,and the noise reduction effect of the stiffened and sound-absorbing materials on the box was analyzed.