Abstract:

：Considering the problems that in existing technology, by using differential pressure compensator or cartridge type flow sensor to control flow will reduce the valve flow capacity and increase the system power loss and heating. The flow only can be indirectly controlled by changing valve opening area in large flow occasion and the control precision is low for the influence of load variation. The controllability is bad and dynamic response is slow when working pressure is low. The structure of three stage larger size valve is complex. So a low energy consumption, high controllable electro-hydraulic proportional valve which is structured by small displacement hydraulic pump/motor driven by servo motor and hydraulic transistor(Valvistor)is put forward. This method can enlarge the valve flow control range and improve the dynamic response of valve in low pressure condition. In research, the static mathematical model of the valve is developed firstly, and the most important factors which affect the characteristic of load flow is the size of feedback slot opening found out by theoretical analysis. Moreover the dynamic mathematical model is developed and the stability criterion of the valve is derived. According to the structure of the valve, the simulation model is established to simulate and analyze the influence of the parameters of valve on the performance of main valve. The simulation results show that reducing the size of feedback slot opening will improve the characteristic of the load flow of the valve. The main valve response speed increases along with the increasing of the pressure drop of the opening of main valve. But the stability of the valve will reduce when the pilot flow is small. The research also show that on the condition of keeping good dynamic performance, making the pilot pump/motor rotation speed change as load pressure varies so that can realize flow compensation of the valve improve the characteristic of the load flow.

Key words: flow compensation, proportional flow control valve, steady state characteristics, Valvistor