Abstract: The flow-control method of pressure compensation is widely used and reliable. But limited by the mechanical structure,there are some shortcomings, such as low control accuracy, single control function, limited flow range and so on, which are difficult to meet the development of intelligent host equipment. Therefore, this study proposes a variable-gain flow-control principle based on active differential pressure regulation. A force control unit is added on the compensator to change the force balance state of the compensator spool, enabling active adjustment of the main valve pressure differential and achieving the purpose of changing gain to control flow. In the study, the principle of variable gain flow control with pressure difference regulation is theoretically analyzed, and a proportional electromagnetic direct drive scheme is given. Then a disturbance compensation strategy is designed to solve the technical problem of the compensator low control accuracy, and a nonlinear flow correction strategy is designed to set the valve flow characteristic curve customize. Finally, experiments are used to verify the feasibility of the proposed principle and designed control strategy. The experimental results show that by continuously controlling the output force of the proportional electromagnet, the differential pressure and flow of the main valve can be changed in proportion, and by changing the differential pressure in real time,the main valve can obtain different flow gains and flow ranges; compensating the flow force, the accuracy of flow control is improved,and the flow control deviation under steady-state load is reduced from 27% to about 4%; adopting the nonlinear flow correction strategy, the main valve flow curve can be set independently, and multiple throttle flow control effects based on the same throttle groove are realized.

Key words: pressure compensator, flow-control method, differential pressure regulation, variable flow gain, flow force compensation, nonlinear flow correction