Abstract: Auto transmission is one of the complicated mechanical mechanisms behaving multi freedom degrees under different working conditions. The present models of auto transmission used for intelligent computing are limited by adaptability, intelligence and consistency from design to characteristics analysis. Therefore, a more efficient, intelligent and systematic method based on graph theory is proposed in this paper. Firstly, the general topological model and shifting topological transformation model of vehicle auto transmission under different working conditions are constructed in the sense of relative speed. And shifting process is mathematically interpreted to judge the topological characteristics of different shifts. Secondly, the general system graph model of planetary gear transmission is established in the sense of absolute speed. The mathematic rules of graph theory model topological transformation are defined. And the transmission characteristics analysis method of planetary gear mechanism is proposed based on graph theory. Finally, the proposed method is proved to be feasible and correct according to the demonstration analysis. Moreover, the research results provide the references for more efficient, intelligent and systematic design of vehicle auto transmission.

Key words: graph theory, topological transformation, transmission characteristics, auto transmission, planetary gear transmission