The Parameter Design Of CVT Hydraulic System With Reflux Power

Continuously variable transmission (short as CVT) with reflux power is super wide in ratio coverage and rather high in transmission efficiency. Moreover, it can continuously regulate speed in its ratio coverage, which leads to engine works at optimum fuel economy curve all along. Therefore, CVT with reflux power will be very promising for research and application.Carried out by national natural science foundation (NNSF), design method for the system of CVT with reflux power has been studied in this paper. The main contents are following.â‘ By discussing characteristics and working conditions of some kinds of electro-hydraulic control system, designing CVT hydraulic control system scheme building hydraulic system flux model, and establishing mathematical model of control valve clamping force, the control process characteristics of hydraulic control system due to system main pressure and speed ratio were analyzedâ‘¡In order to realize the ratio being fast response to satisfy the requirements from driving environment, the dynamic simulation model, which was based on CVT's work characteristic, was established. A design flow and method for calculating the rate of ratio for avoiding energy loss caused by flux overrunning in the hydraulic pump was educed by analyzing the distributing law of the rate of the ratio. The rate of the ratio was the integrated result of the simulation by the car SC7130 in the cases of ECE city cycle driving, EUDC suburb cycle driving, American FTP city and highway cycle driving. The design flow and method established the base for flux model, which is a must for designing hydraulic systems.â‘¢In order to prevent the metal pushing V-Belt skidding and guarantee the engine torque is transmitted efficiently and reliably, by analyzing the forces acting on the metal ring and the metal block, the torque transmitting mode was worked out, and the axial forces acting on driven wheel needed for transmitting torque was calculated.â‘£On the purpose of comparison between CVT with reflux power and metal push belt continuously variable transmission and dual-state continuously variable transmission, the simulation models for such three different CVT have been built, with which the advantages of CVT with reflux power were found contrast to the other two kinds of CVT . through simulation contrast analysis on their performance in the cases of ECE city cycle driving and the steady operation point of engine under different working conditions.