基 于 循 环 功 率 流 的 变 速 器 行 星 轮 系 效 率 分 析

As the core component of automatic transmissions（AT）power transmission，the planetary wheel system has obvious advantages in transmission efficiency，ratio range and load carrying capacity，and its power flow analysis plays an important role in the optimal design. In this paper，an efficiency analysis method of trans⁃ mission planetary gear train based on circulating power flow is proposed. Firstly，the triangular hypergraph of four-row planetary gear train is established based on the hypergraph theory and the transmission power transmis⁃ sion route map. Secondly，based on the self-rotation theory of planetary gear train，the models of gear meshing friction loss and bearing friction loss are established，as well as the speed and torque matrix of the second gear of transmission. Finally，the node power and transmission ratio of the second gear as well as the cyclic power and efficiency of other gears under the condition of no loss and considering two losses are analyzed，and the output planetary gear of the 9AT transmission is tested and verified. The results show that the output power loss of the power transmission ring gear of the three-gear planetary gear train is the largest after considering the two losses，accounting for about 16% of the total output of the ring gear；The ratio of cyclic power to input power in the fourth gear increases by 4%；The experiment shows that the maximum error of efficiency is 4.62% at different speeds and torques. This method can accurately and effectively obtain the power loss and efficiency of the trans⁃ mission during operation.