Vibration Characteristics And Noise Analysis For A Planetary Reducer Of Distributed Electric-drive System

With the diversified development of electric vehicle driving forms,at present,distributed electric driving has become one of the main research directions due to its unique advantages such as simple structure,short transmission chain,and high mechanical efficiency.As an important configuration of the distributed electric drive,the reduction-drive type hub electric drive is easy to produce vibration and noise problems in the planetary reducer mounted on it.The planetary transmission system has a large amount of nonlinear excitation,which makes it difficult to construct an accurate dynamics model and estimate the radiated noise of the reducer.Therefore,this paper takes an planetary reducer which is used on a wheel motor-reducer-type distributed electric drive system as the research object,and combines the theoretical knowledge of elastic mechanics,gear dynamics,finite element / boundary element,and so on to analyze its vibration characteristics and radiation noise,The major research content is as follows:（1）Analyze and calculate the time-varying meshing stiffness,bearing stiffness and planetary pin stiffness inside the gear reducer using the knowledge of elastic mechanics,finite element method,etc.For the planetary transmission system with flexible pins,establish an 18-degree-of-freedom translation-torsional dynamic model with internal factors such as time-varying meshing stiffness,meshing damping,pin flexibility,manufacturing errors and mounting errors of the gear.Deduce and calculate the dynamic meshing force of the gear pair,at the same time,figure out the effect of such as manufacturing error,mounting errors,pin shaft flexibility and other factors on the average value and fluctuation of the gear pair meshing force.（2）Based on the theory of modal analysis,the overall free modal and mode shapes of the reducer in the frequency range of 0 to 3000 Hz are calculated and analyzed.The free modal test was performed on the entire reducer by percussion method,and the test results were compared and verified with the finite element results to initially verify the accuracy of the modal analysis settings.Based on the real situation,a fixed constraint was added to the free modal analysis model to finish constrain Modal calculation.Based on the modal superposition method,frequency response calculation and analysis are performed on the reducer to preliminarily judge the possible noise peak frequency.According to the acoustic radiation theory,the radiated noise of the reducer under the high-speed 4000 r / min operating condition is estimated.Through the analysis of the contribution of the board,the main noise radiation parts on the surface of the reducer box are obtained（3）According to the dynamic model established above,the effects of pin compliance in the dynamic parameters on the vibration characteristics and noise of a6-stage planetary gear reducer were studied.The optimal design of the reducer was performed according to the analysis results of the plate surface contribution,and compared with the original plan,verify the effectiveness of the optimized design.This research provides theoretical basis for the dynamics modeling,radiation noise estimation and structural noise reduction optimization of the reducer,and has certain theoretical and practical application values.