Dynamics Characteristics Analysis And Experimental Study Of A Gearbox

Along with the development of the automotive industry, the quality level isconstantly improved, especially in recent years, introducting the international advancedvehicle technology to localization, the vibration and noise of transmission have morestrict acceptance criteria, so it is more important and urgent to do some research onNVH performance of transmission.There are many factors influencing the NVH performance of transmission,and thevibration and noise produced by gear meshing is considered to be one of the mainfactors. In recent years, many scholars have conducted widespread thorough research tothis area,it is general concluded that improving the gear machining accuracy caneffectively reduce the vibration and noise of transmission. While blindly pursuing highmachining accuracy will encounter many difficulties in production, not only result in ahigh cost,but also have not much potential. So it has been expanded to the field ofcomprehensive management to control the vibration and noise of transmission.This paper takes a domestic five gears manual transmission as the research object,and finds the main factors influencing its vibration and noise by using the method ofcombining theory with experiment.Then some optimizing work is been performed fromthe angle of bearing stiffness. The main research contents are as follows:①Expounding all dynamic incentive of the transmission gear system in detail,and simulating these incentives with numeric values, meanwhile solving thetime-varying meshing stiffness of a helical gear pair through calculating the contact linelength.②Through the stress analysis of helical gear pair, build its bending-torsion-shaft coupling vibration model, then solve its inherent characteristics and response ofsystem under undamped free vibration, and analyze the influence of bearing stiffness onthe system natural frequency.③Solving the system response under the action of internal and outside incentiveby using the ODE15S solver built-in MATLAB, then analyze the difference of systemresponse amplitude under three different bearing support.④Simplifying the model of helical gear pair to a pure torsional vibration model,then analyze the impact of ratio changes on the system response under the condition ofinvariable center distance and other input parameters. ⑤In the semi-dead room, carrying out the experimental study on a certain manualtransmission, at the same time put forward the reasonable vibration improvementscheme combined with relevant experiment results and theoretical analysis.