Taking the high-speedtransmission of an electric vehicle reducer as the research object, firstly, the time-varying meshing stiffness of the gear is calculated by the improved LTCA method, and the meshing impact curve is obtained by using the geometric relationship and mechanical model. Secondly, the bending torsion shaft coupling dynamic model of Helical Gear Considering time-varying meshing stiffness and meshing impact is established and solved. Then, the vibration characteristics of single-stage high-speed helical gear drive are studied, including time-varying meshing stiffness excitation, meshing impact excitation and combined excitation. The main characteristics of vibration characteristics of two-stage high-speed helical gear transmission and the difference between the two-stage high-speed helical gear transmission and single-stage helical gear transmission are discussed. Finally, the vibration reduction of high-speed helical gear transmission by two kinds of tooth surface modification is analyzed effect. The research results of this paper provide a theoretical basis for the design and analysis of high-speed gear transmission, and have guiding significance for its practical application. The main conclusions are as follows
(1) Under the excitation of time-varying meshing stiffness alone, at 1 / 3 and 1 / 2 resonance speeds In the non resonance region, the root mean square value of the relative vibration acceleration does not increase significantly with the increase of the rotational speed; in the over resonance region, the influence of the speed change on the vibration characteristics of the system is not significant; the increase of the average meshing stiffness of the gear pair will reduce the vibration of the system and change the resonance speed of the system; the increase of the amplitude of the time-varying meshing stiffness will cause the vibration of the system to decrease and change the resonance speed of the system The vibration of the gear pair is intensified, but the resonance speed of the system is not changed.
(2) In the non resonant region, the root mean square value of gear relative vibration acceleration increases significantly with the increase of rotational speed; the vibration response of the system varies greatly with different meshing impact time; the longer the meshing impact time is, the greater the vibration response of the system is.
(3) Under the comprehensive excitation, the root mean square value of the relative vibration acceleration of the system increases significantly with the increase of the rotational speed in the non resonant region, but the increase of the system vibration under the comprehensive excitation is smaller than that under the single excitation of the meshing impact; in the over resonance region, the impact of the meshing impact on the system is greater than that of the time-varying meshing stiffness; the higher the speed, the less the influence of the time-varying meshing stiffness on the system vibration, and the meshing impact is smaller Impact is the main incentive component of the system.
(4) In the two-stage helical gear transmission, the vibration of two pairs of teeth affects each other. The vibration response of two pairs of teeth appears the tooth frequency of another tooth pair and the superposition of two frequencies. Moreover, the vibration of input stage tooth pair has greater influence on the output stage tooth pair, which makes the vibration response of the system more complex.
(5) In the second stage helical gear transmission, the input tooth pair has better vibration reduction effect than the output end pair; after the modification of the output end tooth pair, the output end tooth pair only has a good vibration reduction effect on itself, and the input end tooth pair has no obvious vibration reduction effect; therefore, the secondary gear train has a good vibration reduction effect on the input end tooth pair The input gear should be paid more attention to in the design of tooth surface modification of gear system and multi-stage gear system.