Test of a Novel Moving Magnet Actuated Seat Valve for Digital Displacement Fluid Power Machines

The emerging digital displacement (DD) fluid power technology requires a new class of high-performance valves that can operate in harsh high-pressure conditions. To overcome the switching performance limitations of solenoids and to avoid the mechanical complexity of moving coil actuators, a novel electronically-controlled moving magnet actuated (MMA) annular seat valve is proposed, designed, built, and tested rigorously in the laboratory. The actuator is energized using one coil only, it has bidirectional force capability and it utilizes magnetic latching to keep it open instead of a spring. The annular seat valve has two metering edges; the static pressure drop is 0.11/0.31 bar at -142/108 L/min, respectively. The valve closing time is 4-6 ms depending on the flow rate. The MMA valve is tested experimentally in both standalone test rigs besides in situ tests in a fully operational DD prototype machine. Measurements provided for pumping and motoring operation at 800 r/min/100 bar demonstrate that the proposed MMA valve topology is a promising candidate for energy-efficient digital displacement machines. Key characteristics include little power consumption, good switching performance, and a simple mechanical design.