A new design of the variable-pressure hydraulic pump

The conventional variable-pressure hydraulic pump can only work at two or three pressure levels. The outlet pressure is conducted to a piston changing the angle of the wash plate inside the pump by a control valve. A novel design proposed here makes the pump be capable of changing the pressure level continuously. The basic idea is adding a proportional solenoid into the control valve, and the stable pressure level can be determined by the input current rate. Some novel structures are designed to reduce the driving force upon the valve spool. The detailed mathematical model is established, and the dynamics of the system is carefully studied. Using the multi-disciplinary modeling and simulation, the effectiveness of the proposed design is validated and a good performance of changing pressure level is obtained.