Pinion Assembly Strategies for Planetary Gear Sets

Abstract

Previous works illustrate that the orientation of pinion run-out errors has strong effect on the load sharing behavior of floating planetary gear sets. To minimize the inequality of load sharing, an in-phase rule for assembling pinions is recommended by other researchers, while a theoretical proof is still lacking. In this paper, not only the orientation but also the assembly sequence of the pinions is under scrutiny. A generalized mathematical model is developed in order to study the best load sharing conditions and floating gear sets with 4-6 pinions are specially treated. Through statistical calculation, several pinion sequence rules and orientation rules are extracted. By numerical simulation, four different pinion assembly strategies, which originate from the combinations of the existing rules and methods, are compared with each other. The most effective assembly strategies for systems with 4-6 pinions are proposed. The statistical analysis indicates that the proposed strategies significantly improve the load sharing behavior if only pinion run-out errors are considered and retain their effectiveness when pinhole position errors and tooth thickness errors are introduced as interference factors.