Dynamic Analysis of Ravigneaux Planetary Gear Set with Floating Sun Gear

Ravigneaux planetary gear set (RPGS) is widely used in transmission systems. The RPGS studied in this paper consists of two ring gears, a double-planet sharing a carrier and a floating sun gear. Due to the complex meshing relationship, the dynamic characteristics and modulation sidebands of the RPGS are still unclear. This paper proposed a lumped parameter dynamic model of the RPGS. The phase relation of each meshing gear pair is derived based on the geometric position relationship, and the periodic change of the dynamic meshing force vector sum of all planetary gear pairs is considered. Then, the dynamic model is solved numerically by Runge–Kutta method, and the vibration responses of the fixed ring gear and the floating sun gear are analysed respectively. The contribution of this paper is to establish a nonlinear dynamics model of the RPGS and analyze the modulation laws of the meshing phase difference and the periodicity of the meshing force combination on the vibration signals of the ring gear. The results show that the planetary carrier rotation frequency can modulate the meshing frequency and its harmonics of the RPGS system. The force between the wide planet gear and the floating sun gear is alternately positive and negative, and the floating sun gear affects the frequency spectrum of the vibration signal of the fixed ring gear.