Parameter Design Of Power-cycling Hydraulic Mechanical Variable Transmission

In the Power-cycling Variable Transmission(PCVT) system, the torque convert is installed contrary in the reflux line using the power spilt/converging and speed converging inherent characteristics of planetary line, and the ratio of PCVT is changed by the continuous ratio of torque convert and the fixed ratio of mechanical transmission. the PCVT system has higher transmission efficiency and can change its ratio continuously in all range of ratio comparing with the hydrodynamic transmission, friction transmission, and electrical drives etc. what’s more, the engine can be maintained on the optimal operation line by the PCVT. The PCVT system not only increases torque in low speed but also improves the fuel economy performance of vehicle. Hence, it is very worthy to study on the PCVT system. In this paper it is designed that the structural parameters and hydraulic control system of PCVT. The main contents of this paper are as follows:① The basic structure and working principle of PCVT system are introduced. The ratio and efficiency characteristic of PCVT system are analyzed and calculated. The numerical models of engine and torque convert are built to lay a foundation for the structural parameters design and hydraulic control system design.② Based on the design prototype of SC7130 made by Changan Automobile co., LTD, the PCVT is used to its drive train without changing the dynamic performance. The step ratios and the maximum allowable torque capacity are confirmed through calculation and optimum seeking. The structure of PCVT system is designed and it consists of transmission device with fixed gear ratio design, planetary line structure choosing and wet clutch structure design.③ The research on the performance matching and parameter design of hydraulic system is carried out according to the performance requirements of PCVT system. It is proposed that the performance parameter design method of the clutch hydraulic system and the cooling and lubricating hydraulic system, and the displacement of oil pump is selected.④ Based on the required target pressure of clutch in the process of shifting of PCVT, it is analyzed in detail that the change rule and control strategy of following pressure provided by the clutch hydraulic cylinder. The dynamic performance of electric-hydraulic proportional and the basic principle of PID control are introduced. The dynamic performance of clutch hydraulic system is verified by the responses of step signal, ramp signal and sinusoidal signal. The required target pressure of clutch, in the process of shifting, is set as the input pressure in the co-simulation using full vehicle model of Simulink and the hydraulic control system of AMEsim. The simulation results show that the dynamic performance of clutch hydraulic control system is good enough to meet the pressure requirements of the PCVT system on clutch.