Study On Meshing Characteristics And Vibration Reduction Of Transmission Helical Gear System

With the popularity of automobiles,automobile comfort has gradually become an evaluation index considered by the public.Its vibration and noise is the main aspect that affects automobile comfort.Therefore,the large vibration and noise of automobiles will affect consumer’s purchase expectations.Vehicle vibration and noise are related to vehicle NVH problems,and transmission NVH problem is one of the main sources of vehicle NVH problems.In order to meet the needs of consumers,transmission vibration and noise reduction research came into being.Gear profile modification is a main method of vibration reduction and noise reduction,which is of great significance for reducing transmission NVH.In view of this,this paper takes the first reduction gear set of a 6AT transmission as the research object,studies the mechanism of vibration and noise generation of the gear set,constructs the analytical model of helical gear meshing stiffness and transmission error for gear modification,carries out double-objective optimization based on this model,and then constructs the dynamic model of gear system coupled with gear-bearing-rotor,and combines the modification parameters of the optimization scheme with the dynamic model to calculate the low The main research contents of the vibration characteristics of the modification scheme under high torque conditions are as follows:First of all,analyze the gear contact situation in the process of helical gear engagement,consider the variation law of the meshing stiffness on the helical gear tooth profile surface and the evolution law of the helical gear engagement line,propose an analytical model of the nonlinear meshing stiffness of helical gears with large contact ratio based on the energy accumulation method,and establish the analytical model of transmission error,verify the accuracy and accuracy of the model through the finite element simulation software,analyze the internal The influence of external excitation on the transmission error of helical gears lays a foundation for the research of gear modification.Secondly,the theory of tooth profile modification and tooth alignment modification is introduced.By combining the tooth surface parameter coordinate system,the tooth profile modification and tooth alignment modification parameters are introduced into the analytical model of helical gear transmission error.Considering the variability of torque and the uncertainty of surface roughness in gear manufacturing,the robust optimization strategy for tooth surface modification is designed based on NSGA-III algorithm,The influence of different modification schemes on the peak to peak value of transmission error and contact load of tooth surface is analyzed.Thirdly,the primary reduction gear set is divided into gear mesh units and other units of the transmission(including shaft,bearing and box foundation units).Each unit is coupled through the finite element method to build its bending torsional shaft pendulum fully coupled helical gear system dynamic model.The scheme parameters are optimized in parallel through Newmark-β Method for iterative solution;Based on this model,the natural frequency and time domain response characteristics of the system are analyzed,and the influence of different gear modification schemes on the vibration characteristics of the system is analyzed.Finally,an experimental platform is built to locate the vibration source and sound source of the transmission based on the order tracking theory,and the vibration and noise experiments under different working conditions are designed to analyze the order noise conditions of the third and sixth gears before and after the modification,and verify that the modified first reduction gear set can effectively improve the NVH performance of a 6AT transmission.