Control Of Automotive Gearbox Whine Based On Gear Tooth Modification

Automotive gearbox is an important part of the automobile transmission system and also a main source of noise and vibration,thus has a significant influence on the NVH performance of the vehicle.So far,no domestic automotive company has mastered a reliable method for the control of noise and vibration of gearbox,and it has long been an obstacle to the development of domestic automobile industry.In this paper,a manual gearbox is studied in order to understand the test,dynamic modeling and model verification process of gearbox,and also the transmission error optimization method based on genetic algorithm and gear modification is explored.The analysis of the vehicle test shows that the contribution of the gear order noise to the noise of the transmission and the vehicle is quite considerable,and the sensitivity of the different positions in the vehicle to the order noise is different.The experiment also finds that the tooth frequency and its harmonics is much more difficult to isolated by noise-proof measures than other noise like gear rattle.A bench test is carried out for further study of the gearbox noise.The noise are analyzed in different directions,different distances and different working conditions,the 3rd and 5th gear are the focus of analysis and the effect of gear order noise on overall noise level is discussed.Static transmission error under various operating conditions are tested.The transmission error signal is processed by band pass filtering and fast Fourier transform,and the components of the tooth frequency and its harmonics are extracted.Correlation coefficients show a relevance between STE and tooth frequency noise in low speed range.Modal test of the gearbox housing find that there are too many local modals of the front housing in low frequency,in order to reduce the response reinforcement measures should be taken to improve the stiffness of the front housing.A dynamic model of the gearbox is built using the Romax Designer a software developed by Romax Technology,the housing of the gearbox of is introduced into Romax Designer by means of FEA using Hypermesh to take housing compliance into consideration.Model analysis is carried out in Romax Designer,the result is compared to test result to confirm the model building process.The dynamic response of the gearbox under 3rd gear condition is simulated using the model built,prediction of static transmission error and the following vibration of the housing are compared to test data,and the results are satisfactory enough.A static transmission error calculation model is established based on the slice method,with which the static transmission error and tooth surface stress can be calculated.Influence of load and modification parameters on the transmission error is explored,and these influence laws can be used as reference for the modification work.Furthermore,the optimization of gear modification become possible by using genetic algorithm,and the results prove to be practical after validate in dynamic model.This method can provide strong support for the determination of low noise gear modification combined with dynamic model.