Taking the high-speedtransmission of an electric vehicle reducer as the research object, the vibration characteristics of the system under three excitation modes of time-varying meshing stiffness single excitation, meshing impact single excitation and both comprehensive excitation are analyzed; the difference of vibration characteristics between single-stage helical gear transmission and two-stage helical gear transmission and the phenomenon of mutual influence of two teeth on vibration are studied; the tooth surface modification pair is discussed The influence of the system on the vibration reduction effect. The main research work of this paper is as follows
1.The status quo of high-speed development of electric vehicle industry in recent years, as well as the problems caused by high-speed input of electric vehicle reducer, put forward the research background of higher requirements for the development and design of reducer; on the basis of consulting a large number of literature, the vibration characteristics of gear transmission under time-varying meshing stiffness excitation and gear transmission vibration characteristics under meshing impact excitation are analyzed At present, the research status at home and abroad is analyzed from three aspects: vibration characteristics of electric vehicle reducer, high-speed gear transmission system, and mutual transmission of vibration between multi-stage gear systems.
2.Calculation of time-varying meshing stiffness of helical gear. The formation mechanism of time-varying meshing stiffness is analyzed, and the time-varying meshing stiffness of helical gear transmission of electric vehicle reducer is calculated by material mechanics method, finite element method and improved load contact analysis method, and the calculation results of the three methods are compared. Thus, the feasibility of calculating the time-varying meshing stiffness based on the improved load-bearing contact analysis method is verified.
3.Meshing impact analysis and calculation of helical gear transmission. Firstly, the formation mechanism of meshing impact is analyzed, and the influence of meshing impact on the vibration characteristics of helical gear transmission system is determined. Secondly, the meshing impact time is derived from the geometric relationship of gear line engagement impact, and the influence of system parameters on the meshing impact time is discussed. The meshing impact velocity and the meshing impact force amplitude are calculated by using the relevant theoretical relations in impact mechanics. Finally, according to the meshing impact time and the meshing impact force amplitude, the meshing impact force curve is expressed by sawtooth wave.
4.Vibration characteristics of single-stage high-speed helical gear transmission. Based on the time-varying meshing stiffness curve and meshing impact force curve obtained, the vibration characteristics of single-stage helical gear drive with time-varying meshing stiffness, meshing impact and combined excitation are analyzed. The influence of time-varying meshing stiffness and meshing impact on the vibration of helical gear transmission is compared size.
5.Vibration characteristics of two-stage high-speed helical gear transmission. The dynamic model of two-stage helical gear transmission is established. The vibration characteristics of two-stage helical gear transmission under time-varying meshing stiffness excitation and meshing impact excitation are studied. The main characteristics of vibration response of two-stage helical gear transmission are analyzed, and the characteristics of mutual influence and transmission of vibration between two teeth of two-stage helical gear transmission system are proved.
6.Influence of tooth surface modification on vibration characteristics of high speed helical gear transmission. This paper describes the basic principle and common methods of tooth surface modification The software establishes the dynamic simulation model of high-speed helical gear transmission of electric vehicle, and carries out tooth surface modification, simulates the bearing transmission error of the modified gear, and then obtains the time-varying meshing stiffness of the modified gear; the simulation results of the tooth surface load before and after the repair are obtained, and the simulation results are compared; finally, the comparison and analysis of the two-stage helical gear transmission is only for the input end of the tooth pair repair The results of the vibration response of the system are obtained under the condition of two kinds of training forms, i.e. the form and only the output tooth pair modification.