Design And Simulation Of Hydro-Mechanical Continuously Variable Transmission

HMCVT is combined properly by hydraulic and mechanical transmission, which has characteristics with variable speed of hydraulic transmission and high efficiency of mechanical transmission. The adoption of the device can greatly improve vehicle's power> economy and the level of automation. Based on the introduction about the classification,characteristics and current development status of variable transmission, it shows the purpose and significance of studying HMCVT. This paper analyzed the structure features,principle and various characteristics, which provided the theoretical support for designing this system.On this basis, putting dongfanghong C702 series-tractor as a target, then designed the HMCVT. The structure of this system has three forward blocks,two back blocks withal fixed axis gear shunt and planet row collective cent. Meanwhile, combine to the actual working demands of tractor, the structural Parameters of HMCVT are obtained by optimization design method. The stepless speed characteristics, torque characteristics, Power split characteristics,power flow characteristics, efficiency characteristics of HMCVT are analyzed.Tractor requires frequent braking in the course of its work. In this process, it will loss much energy, so braking energy recovery is an effective energy-saving method. On the basis of HMCVT, I designed a set of braking energy recovery system, simultaneously, using the energy of this part to start the tractor. This is equivalent to pure hydraulic launch, which is more favorable for the start of vehicles. The program not only achieves the purpose of energy saving but also improves the dynamic performance of vehicles.Create the physical model of the HMCVT with AMEsim. Then, simulate the stepless speed characteristics, torque characteristics, Power split characteristics,power flow characteristics, efficiency characteristics. Simulation results show that:this HMCVT with braking energy recovery meets the design requirements, meanwhile, it has excellent characteristics,higher transmission efficiency and significant energy recovery which can be used for vehicle's starts.