Research On Dynamic Response And Contact Fatigue Performance Of Torsional Stiffness Of Scissors Gear To Gear System

In today’s society,Noise,Vibration,and Harshness(NVH)performances are increasingly being valued by automobile drivers.The vibration response of automobile engine and gearbox system,as the most important excitation port of automobile NVH,has become a research topic of all major machinery factories and scientific research institutions.Gear transmission is the most important transmission mode in automobile gearboxes.Therefore,the dynamic vibration response of the gear transmission structure system directly affects the NVH performance of manual gearboxes and even the entire vehicle system.This paper mainly studies the torsional stiffness of the scissors gear to the dynamic response characteristics of the gear train.Firstly,the theoretical analysis of the gear mesh stiffness is carried out.On the basis of the theoretical analysis,the dynamic model of the gear system is constructed and solved,and then the different effects of the rigid scissors gear on the rear axle of the air compressor is simulated and the force distribution is studied.Finally,the NVH performance test and analysis will be carried out by simplifying the model.The main research contents of this paper are as follows:(1)The theoretical analysis of gear meshing stiffness was carried out,and the stiffness calculation formula under Hertz contact energy,bending energy,shear energy and axial extrusion energy was constructed.Assumed that the number of teeth of the meshing gear is Z1 = Z2 = 30 and Z1 = Z2 = 60,the results of the proposed basic energy method were compared with the standard model.It was found that when the number of teeth of the active and passive gears was equal to 30,the single tooth calculated by the basic energy method,finding that the meshing stiffness was relatively large,and when the number of teeth of the active and passive gears was equal to 60,the stiffness calculation model that only considers the transition fillet deformation of the tooth root was smaller than the standard stiffness.(2)Constructed a 12-degree-of-freedom dynamic model of a quadratic standard cylindrical gear,and proposed a gear system dynamic model with geometric eccentricity error to determine whether there was eccentric coupling based on two considerations and problems.Consider the dynamic model of coupling terms.Research conclusion: The Runge-Kutta method of the general solution of differential equations was used to solve the dynamic model with or without coupling terms.According to the results of the solution,it was found that the model considering the coupling term was better than the model without considering the coupling term.The coupling term only affected amplitude modulation influence,the coupling term had no obvious influence on the position of the correlation peak in the spectrum.(3)The simulation of the influence of scissors gears with different stiffness on the rear gears of the air compressor crankshaft was studied.Through simulation and comparison of the contact curves between the rear gear of the crankshaft and the imported and domestic scissor gears,it can be seen that the imported scissor gear with high torsional stiffness meshes better with the rear gear of the crankshaft,while the domestic scissor gear with low stiffness had more non-contact during the meshing process.Indicating that there were more collisions between meshing gears.Comparing the force diagram,it can be seen that the maximum force on the slice during meshing with domestic scissors gear was 323 N,and the maximum force on the slice during meshing with imported scissors gear was 327N;comparing the tooth surface contact pressure diagram,it can be seen that it meshes with domestic scissors gear The maximum contact pressure on the slice during the process was 905 MPa,and the maximum contact pressure on the slice during the meshing process with the imported scissors gear was 911 MPa.(4)The vibration mechanics and abrasion performance of plates with different stiffness were analyzed through simplified models.The research showed that the rapid decay response to the free vibration decay curve of different stiffness can get the larger the initial amplitude of the material with the greater stiffness,and the faster the amplitude attenuation speed,indicating that it was more difficult to cause its own vibration by external excitation.The power density function(MSA)of vibration obtained by fast Fourier transform(FFT)can be obtained at the same vibration frequency,the greater the stiffness of the material,the power density function had a lower response value.The stiffness of the material itself had a direct effect on its vibration performance.The greater the stiffness of the material,the better its vibration resistance.The wear test results showed that the wear amount of imported steel gears with greater stiffness was significantly less than that of domestic steel gears with lower stiffness.The microscopic surface morphology was also more complete,indicating that gears with greater stiffness had less wear.