The Influence Research Of Main Reducer Gear System Support Stiffness On Drive System

Mini-car rear axle, as the drive axle, is at the end of the power transmission system. Gear drive system of the main reducer is the bridge of power transmission in mini-car rear axle, and changes the transmission direction, reduces the speed and increase the torque of power form the drive shaft to the left, right half shaft, finally to the wheel, to make the vehicle run normally. Gear drive system an important component of the main reducer, and its vibration and noise situation directly affects the driving stability and riding comfort. With the rapid increase of China’s city and rural people’s living standard and the substantial growth of domestic mini-car manufacturing industry, consumers are not only to pursue of bargain price and multi-function, and put forward the higher requirements of the car comfort and safety. Today, the performance of NVH has become one of the important indexes for evaluating the comprehensive performance of mini car.In paper, based on the vibration response of the system, gear pair and bearing, bearing support stiffness is one of the main influence factors of system vibration under the present technological level.The bearing support stiffness is deeply studied through theoretical calculation, simulation analysis and experimental demonstration, to achieve the system stiffness optimization design for the gear drive system.Firstly, the theoretical dynamic model is established, using the iterative calculation method and transfer matrix method, to obtain the reasonable span between the supporting bearing of the gear drive system.During the iterative calculation, The solution of the maximum stiffness of system is transformed into solving minimum deflection. Considering the elasticity of the gear shaft and bearings, the deflection formulas are respectively established, caused by the contact deformation of bearing and gear shaft bending deformation, and are combined simultaneously to achieve the total deflection formula. the bearing support span of the minimum deflection is figured out, with the iterative principle.During the transfer matrix calculation, based on the structure characteristics of components, the system is discretized into several feature unit. The bearing support stiffness is introduced into the elastic support unit. The transfer matrix of the feature units are respectively established, and are combined simultaneously to achieve the total transfer matrix. The system natural frequency and vibration mode under the different bearing span is solved by Matlab software, with the the free end as constraint conditions and are verified by Ansys analysis. Compared to the system resonance frequency, the reasonable bearing span is found out, which is as much as possible to avoid the system resonance and behaves the best vibration situation.Secondly, the system vibration response under the different bearing span is solved by Adams dynamics simulation analysis. Finally, the vibration and noise situations of the before and after the improvement of bearing support span are compared through vibration and noise test system. The theoretical calculation of the optimal bearing support span is further proved through the simulation and test analysis and the improvement measures is acquired, to optimize the support stiffness of the gear drive system.