An Augmented Lever Analogy Method for Kinematic Analysis of Dual-Input Planetary/Epicyclic Gear Sets Involving Planet Gear

The lever analogy method (LAM) is a translational system representation for the rotating components and is widely used for the kinematic analysis of PGSs/EGSs. However, it includes only the sun gear, ring gear, and carrier, and ignores the kinematic information of the planet gear. The planet gear kinematic information is vital for its bearing life prediction, and speed sequence, power flow, and efficiency analysis of dual-input PGSs/EGSs. The traditional LAM doesn’t work when involving the planet gear kinematic information, because the kinematic information of planet gear is eliminated during the process of merging similar items. In this paper, an augmented lever analogy method (ALAM) is proposed to make up for the lack of traditional LAM in analyzing planet gear kinematic information, and analyze the kinematic relationship between planet gear to other components for the dual-input PGSs/EGSs. In this method, the new nodes and lever lengths representing the planet gear are added to the LAM by analyzing peripheral velocity relationships at the meshing points of PGSs/EGSs. In addition, not all the dual-input compound PGSs/EGSs (e.g. the compound PGSs/EGSs with planet gears in series, etc.) can be analyzed by the traditional LAM. The proposed method can easily establish the augmented lever models for all of them and derive the corresponding kinematic expressions. The results show that the proposed ALAM has good visibility and greater versatility, and can accurately and efficiently calculate the rotating speed of planet gears for calculating the speed sequence, power flow, and efficiency of PGSs/EGSs, which can cover all kinds of the PGSs/EGSs, and greatly reduce the technical threshold and time for their kinematic analysis.