Development of piezohydraulic actuator driven by piezomembrane pump

A piezohydraulic actuator (piezopump-driven cylinder system) has the advantage over the conventional contact/non-contact piezoelectric motors in terms of achieving large thrust, high velocity, and long traveling distance. In this study, a serial-connection 5-chamber piezomembrane pump (SCCPP) was introduced and used for replacing piezostack pumps so as to decrease cost of piezohydraulic actuators. The border-upon piezomembranes work in anti-phase, a SCCPP is equivalent to several single-chamber pumps running in series. The theoretical study suggests that the performance of a SCCPP-driven actuator depends mainly on the efficiency of check valves, structural parameters of piezomembrane/pump chamber/cylinder, the number of pump chambers, and liquid bulk modulus. A piezomembrane has an optimal thickness ratio (metal to piezoelectric) for the actuator to achieve maximal power. A SCCPP-driven actuator was fabricated and tested under three/four/five chambers running. The testing results show that the thrust, velocity, power, and even optimal frequency of the piezohydraulic actuator all increase linearly with number of working chambers and driving voltage. At 180 V and 280 Hz, the achieved thrust, velocity, power, and step length from the actuator under five piezomembranes running are 75 N, 9.8 mm/s, 184.5 mW, and 35.2 µm, respectively, which are about 2.1/2.7/5.7/2.7 times than those of three piezomembranes running.