Unified Pressurization and Valving for Smart-Material Based Electrohydrostatic Actuators (EHAs)

Smart material-based actuators have shown promise as compact units for generating fluid power. These actuators have been successfully built to operate at high frequencies, but valve limitations have consistently reduced overall performance. Both passive and active valve concepts have been designed and tested. Passive reed-type valves are simple and compact, but fail to fully open and close during high frequency operation. Conventional active valves require additional drive and control hardware that reduces the power density advantages of this class of actuators. Unified pressurization and valving techniques will be studied as a means to overcome the limitations of the passive and conventional active valves. The unified valving concepts make use of existing architecture in the pressurization systems, employing piezoelectric, magnetostrictive, or similar smart materials, and couple compact valve sets to the assembly. Concepts will be developed using direct and levered mechanical coupling, with an alternate design using magnetic flux. Pump pressurization volumes will be modified if necessary. Computational fluid and structure modeling will support selection of a preferred design. A valve subassembly will be built and tested in conjunction with an existing pump. Phase 2 will build multiple pumps with the new valve systems and ready them for UAV flight demonstration.