Dynamic characteristics of the floating non-loaded ring gear with external spline teeth in Ravigneaux planetary gear sets

Abstract

When analyzing the dynamic characteristics of Ravigneaux planetary gear sets, the vibration of loaded parts is often paid more attention than non-loaded part since that it is theoretically believed to transfer no power. However, a failure problem is found that the non-loaded part does vibrate seriously and so causes the crack in the middle zone between two spline tooth roots when driving the clutch friction plates to rotate synchronously. The finite element method is applied to model the whole Ravigneaux planetary gear set with two ring gears. The simulated result proves that the floating non-loaded ring gear burdens transient high-frequency acceleration and deceleration impact from planet gears. The sectional stress distribution is analyzed for the floating ring gear under the impact. The middle zone between two internal tooth roots has large stress, and the same characteristics exists for the external spline teeth. This vibration of the floating non-loaded ring gear is the final excitation source for the clutch friction plates driven by the floating ring gear. This work is of high value for controlling the vibration level of the floating ring gear and solving the fracture fatigue problem of its matching friction plates in Ravigneaux planetary gear sets.