Piezoelectrically actuated hydraulic valve design for high bandwidth and flow performance

The performance of hydraulically actuated machine systems could be improved with the use of valves that have high bandwidth and high flowrates under low pressure drops. Although high flowrates can be achieved using very large spool strokes and/or diameters, the overall bandwidth of the valve will be reduced. Research has therefore been undertaken on a prototype valve design incorporating the Horbiger plate principle, which utilizes multiple metering edges to allow high flowrates to be obtained at low pressure drops and small poppet displacements. The valve is directly activated using a piezoelectric actuator to achieve a fast dynamic response. Valve performance is assessed using a mathematical model that includes the piezoelectric actuator and power amplifier, the supply flow, fluid squeeze forces, end stop response, and valve mechanical components. The steady state relationship between valve flow, force and pressure drop, and the fluid inertance, were determined using computational fluid dynamics software. The simulation model has been validated using test data obtained from experimental tests undertaken on a prototype valve. Good agreement is obtained between the predicted and measured results and it is shown that the valve is capable of opening or closing fully in less than 1.5 ms, and can pass a flow of 65l/min at a pressure drop of 20 bar.