Abstract: Hydro-mechanical continuously variable transmission is a new kind of transmission,with the features of continuously speed regulation and high efficiency.According to a new type of hydro-mechanical continuously variable transmission,the design of hydraulic control system is carried out,through the analysis of the open hydraulic circuit and the closed hydraulic circuit,combined with the actual control needs of transmission,the closed hydraulic system is more suitable for the transmission. Using the AMESim for the modeling and simulation of the hydraulic system respectively,by analyzing the pressure-flow characteristic of the pump-motor system,the system power split-flow and the efficiency characteristic of the system both of the open and closed circuit hydraulic system,confirmed the rationality of the closed hydraulic system.

Key words: continuously variable transmission, power split-flow, efficiency characteristic