The Research Of Digital Variable Displacement Pumps Based On High-speed On/Off Valve

Pumps are essential core components in hydraulic control system, which influence performance of hydraulic system directly.In order to increase the energy efficiency and the control performance of hydraulic system, variable displacement pumps are used widely.The realization of variable displacement pumps have two ways of motor variable frequency speed-regulating and change displacement. But larger inertia and slower dynamic response are in the two ways, which seriously influence the overall performance of hydraulic system.In view of the shortage of the above-mentioned variable displacement pumps, design a digital variable displacement pump to achieve the variable functionality by combining a fixed displacement pump, a high-speed on/off valve, a cartridge valve, an accumulator etc under closed loop feedback control. As cartridge valve using the high-speed on/off valve as the pilot valve instead of the stroking mechanism of ordinary variable displacement pumps, faster response can be expected by eliminating the intervening inertias of the stroking mechanism control system. Enlarge the variation range of variable displacement pumps'flow or pressure to improve efficiency and control performance of hydraulic systems by controlling the PWM signal.The related characteristics of high-speed on/off valves and cartridge valves were analyzed and the control strategy of high-speed on/off valve-controlling cartridge valve as the pilot control device of digital variable displacement pumps was elaborated. The kinder of control formula was the two-position three-way high-speed on/off valve-controlling cartridge valve, which was chosen as the pilot control device of digital variable displacement pumps by principle analysis, mathematical equation established and AMEsim software simulation. Then established the overall control formula of the digital digital variable displacement pumps, studied the feasibility of control formula and the different parameters influence on the performance of digital variable displacement pumps by principle analysis, mathematical equation established and simulation. Finally, by closed-loop feedback optimal control, decreased the ripple size of output pressure and the response time, and achieved the best control performance of the digital variable displacement pumps.