The load sharing structure design and FE analysis of planetary gearbox with flexible pin

Abstract

The paper first introduced the unequally load sharing in the planetary gear set and explained the cause of unequally load sharing in traditional design. Then a new floating structure of planetary gear with flexible pin has been designed to improve unequally load sharing of planetary gear set. In order to verify the flexible pin structure effects on the load sharing, two integrated finite element models have been built. Each one consists of two coupled planetary gear sets. One finite element model has been built with flexible pin structure and the other with fixed pin. The same load and boundary conditions have been applied to the two different finite element models. After analysis, the vonmises stresses of different parts such as ring gear, planetary gear, bearing and pin etc. in two different models have been compared. From the analysis result verification, the maximum vonmises stress of flexible pin of planetary gear set is much higher than that of planetary gear set with fixed pin in different mesh position. Although it is in the design range of material strength, its increase indicates that flexible pin structure makes the higher unequal mesh load of planetary gear shared with other pinions, the deflection of flexible pin make the load sharing with other pinions possible. Whereas the maximum vonmises stresses of other parts such as ring gear, planetary gear, bearing and sun gear decreases in a certain degree with the flexible pin deflection. It really indicates that the effect of flexible pin in the planetary gear set is obvious against fixed pin. When the higher unequally sharing load becomes smaller, maximum vonmises stresses of all planetary gear set parts except flexible pin become smaller and safer.