Dynamic Modeling of Planetary Gear Train for Vibration Characteristic Analysis

In this paper, a torsional-translational coupled nonlinear dynamic model for planetary gear train with three planet gears is developed to investigate its vibration characteristic. In this lumped-parameter model, gears and carrier all have three degrees of freedom: two translations and one rotation. The equations of motion of the dynamic model are built in consideration of gear elastic deformation and time-varying mesh stiffness. Gear elastic compatibility equations are developed to describe the relationship between displacements, elastic deformations and transmission errors. Thus, dynamic equations of the planetary gear train consist of equations of motion and gear elastic compatibility equations can be found and the effects of support stiffness and flexible planet pin on vibration characteristic have been addressed. The results show floating central gear and flexible planet pin can avoid critical operating conditions, which provides a theoretical guideline for the design of planetary gear train.