Synthesis of multi-row and multi-speed planetary gear mechanism for automatic transmission

The multi-speed planetary gear automatic transmission (AT) can improve the engine fuel economy and the vehicle ride comfort. And multi-speed AT could be achieved by multi-row planetary gear mechanism (PGM). A systematic design method is explored to synthesize the configuration schemes of multi-row and multi-speed AT based on the lever analogy in this paper. Hybrid connection (HC) of 3-row is selected as preferred connection and taken as an example to deduce the synthesis process based on the analysis of connection of 2-row and 3-row PGM. Lever output of the HC of 3-row PGM is analyzed when it is split into a single-row PGM (SPGM) and a double-row parallel PGM (DPGM) lever. SPGM and DPGM lever are properly matched with components. And the matching criterion of DPGM is summarized in light of the infeasible matching schemes. Furthermore, the lever schemes of 3-row PGM AT are synthesized by arranging the power and link elements. It is proved that the lever schemes can be used to design multi-row and multi-speed AT not only for single power vehicle but also for hybrid power vehicle. This paper will provide theoretical reference for design of multi-row and multi-speed AT.