Study on the Design Method of a New Hydro-Mechanical Continuously Variable Transmission System

A design method for a new power-cycling hydro-mechanical continuously variable transmission (PCHMCVT) system is proposed in this study. The transmission efficiency in this method is defined to be the design standard. The design target ensures the maintenance of the transmission efficiency at more than 80% in different driving modes. In this study, the primary structural parameters are first calculated with respect to the PCHMCVT for the Dongfanghong 1302R tractor, based on the tractor's required traction. Moreover, the original transmission structure is improved for the purpose of improving transmission efficiency in the reverse gear mode through the simulation analysis. Thereafter, according to the speed requirement of the tractor and the speed ratio continuous condition of PCHMCVT, two gears and five working modes (four forward modes and one reverse mode) are designed to maintain the tractor to operate high efficiency at different driving modes. Finally, PCHMCVT has more powerful low-speed torque-increasing characteristics and vehicle power commutation characteristics based on the simulation analysis of the tractor's basic characteristics and then proved the feasibility of PCHMCVT design method.