Numerical investigation to vibro-acoustic responses of HEV transmission with compound planetary gear train

Abstract

A deep hybrid electric vehicle (DHEV) equipped with a Ravigneaux compound planetary gear train (PGT) encounters severe gear whine noises during acceleration in EV drive mode. For the analysis of vibro-acoustic sources, a 5DOF lumped-parameter vibration model for the PGT dynamic system is established as well as sound pressures radiated from the transmission on test bench are measured for data processing and recognition. By comparison between numerical and experimental analyses, natural vibration modes of the PGT are examined and the high frequency modal resonances in association with the planetary gears are observed only to cause a narrow band whine noises. Furthermore, a 2DOF reduced dynamic model for the planetary gears with consideration of nonlinearities such as time-varying mesh stiffness and backlash is proposed and numerical solutions to bifurcations and dynamic in stabilities of the two sets of planetary gears are obtained. It is found that nonlinear vibration behaviors of the long and short planets are major causes of shock and vibration of the hybrid transmission. Severe vibro-acoustic noises excited dominantly by the planetary gear system are alleviated after implementing micro modifications for the PGT.