Analysis And Optimization Of Gear Whine Of Transmission

Transmission is one of the important parts of automobile transmission system,its performance directly affects the performance of the whole vehicle.Transmission noise has become one of the increasing NVH problems reported by vehicle users.Therefore,it is urgent for the automotive industry to address transmission noise.Aiming at the noise problem of the dual clutch transmission produced by a certain enterprise,this paper studies the influence of the macro basic parameters and the micro modification parameters of the gear on the whine by means of experiment and simulation analysis,and solves the noise problem of the transmission from the aspect of excitation source.The main work of this paper is as follows:In order to find the excitation source of gear whine,road test,bench test,gear contact pattern test and test data analysis were carried out on the transmission.According to the transmission structure parameters and order analysis method,the vehicle road test data are calculated and analyzed.The results show that the gear whine of transmission is mainly the21st order noise of the second gear.By extracting the order slice,the highest order sub-sound pressure level is found to be about 46d B（A）,which is 6d B higher than the enterprise standard.In order to eliminate the interference of external factors during the vehicle road test,the single transmission bench test was carried out,and the results were consistent with the vehicle test.In order to understand the meshing condition between gears,the contact spot test was carried out.The results showed that the load distribution of the gear contact pattern test on the tooth surface of the second gear was not uniform,indicating that the meshing effect between gears was not good.In order to solve the problem of transmission noise,the transmission dynamics simulation model is established based on Romax software,and the accuracy of the model is proved by the test.Firstly,the modeling and assembly of shafting,gears,bearings and other components were completed.The finite element model of gearbox box established by Hypermesh software was imported into Romax.In order to improve calculation efficiency,the model was dynamically polycondensation,and then the tooth stiffness and transmission error of the second gear pair were simulated and calculated.As the internal excitation of the gear transmission system,the left and rear mount vibration acceleration response curves of the transmission were calculated and compared with the transmission single bench test results.The variation trend of the two was basically the same,which verified the reliability of the built model and laid a model foundation for subsequent research.The meshing stiffness of helical gears was solved by slicing method,and the influence of contact degree on meshing stiffness of helical gears was studied by changing the macroscopic basic parameters of gears.The results show that the fluctuation of meshing stiffness is small when the transverse contact ratio or the overlap contact ratio approaches the integer,while when the the overlap contact ratio and the transverse contact ratio are not close to the integer,but when the total contact ratio approaches the integer,the fluctuation of meshing stiffness is large.Based on the above research results,the gear macro parameters were optimized,and the transmission error peaking value and first-order harmonic amplitude were reduced by 0.53μm and 0.25μm,respectively,and the mean value and fluctuation value of meshing stiffness were reduced by 6.33×10⁶/（N/m）and4.95×10⁷/（N/m）,respectively.In order to control the whine of gear,the tooth profile and tooth orientation of gear were modified by orthogonal design and tolerance analysis method.By orthogonal design of microscopic modification parameters of gear,the optimal modification quantity of comprehensive tooth profile oblique modification f _Hα,comprehensive tooth profile drum C_α,comprehensive tooth profile oblique modification f _Hβand comprehensive tooth profile drum C_βare 11.1μm,6.7μm,13.3μm and-23.3μm,respectively.The simulation results show that the transmission error is reduced by 0.25μm before and after gear modification,the gear contact pattern are more evenly distributed in the middle of tooth surface and the contact spots area is increased,and the load per unit length of tooth surface is reduced by60.1N/mm.The tolerance of gear micro modification parameters was analyzed and the manufacturing tolerance range of each parameter satisfying the optimization purpose was determined.The results of simulation analysis after optimization are compared with the results before optimization.The results show that the acceleration of left and rear mount vibration decreases by 3.4m/s²and 3.8m/s²on average.The test results show that the gear whine of the transmission can be reduced and the noise evaluation standard of the gear can be satisfied.In this paper,the mechanism of transmission noise is studied by the method of experiment and simulation,and the macro-parameters and micro-modification parameters of gear are optimized,which provides reference for similar problems in practical engineering.