Design and numerical simulation of a continuable and bidirectional piezo-hydraulic servo pump

Hydraulic servo pump is extremely important to achieve high dynamic performance and large power density of distributed actuation systems in modern aircrafts. In this study, a piezo-hydraulic servo pump (PHSP) with multiple piezoelectric stacks (PZT stacks) is proposed. The key feature of this design is the development of a mutual active valve rectification method. Based on the novel rectification technology, the PZT stacks operate in phases to acquire a continuable oil supply of PHSP, which is unreachable in conventional single PZT stack driven pump. Moreover, the flow rate and flow direction of this pump can be adjusted as demanded rapidly and conveniently. The mutual active valve rectification method is also available when more PZT stacks are incorporated into the pump to achieve larger power output. This paper presents the design concept and working principle of PHSP. A dynamic model is formulated analytically to validate the system principle. The simulation results are acquired to evaluate the pump performance. A research prototype is developed for experimental purpose and control implementation.