Dynamic Characteristics of Torsional Vibration of Urban Rail Vehicle Gear System Under the Condition During Variable Speed Process

Abstract

Urban rail vehicle works under the conditions of the variable speed, and the traditional method of gear system under constant speed condition cannot meet the needs of the dynamic characteristics analysis. Therefore, a new method of gear system under the time-varying load and speed condition is proposed to investigate the dynamic characteristics. Considering the influences of the time-varying mesh stiffness, time-varying external excitation, the static transmission error, random displacement excitation and nonlinear backlash, the torsional vibration model of the gear system is established. The calculation formula of gear meshing frequency is corrected by analyzing the meshing process of spur gears. Based on the cumulative integral method, the velocity, the rotational speed and the angle of the shaft are calculated for the conditions of the coasting, traction and braking, respectively. The results reveal that the power density of the gear torsional vibration in the traction condition is the lowest among the three working conditions. Under the coasting condition, the gear system presents fractional frequency phenomenon at low speed, and it has a trend of turning into chaos at high speed; under the traction condition, the stability of the gear system is decreased with the rotational speed; under the braking condition, the torsional vibration of the gear system does not show the influence of the meshing frequency.