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Development of a Plastic 3D Printed Valve for Small-Scale Electrohydrostatic Actuator Applications

Date

2022-12-16

Journal Title

Journal ISSN

Volume Title

Publisher

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Type

Thesis

Degree Level

Masters

Abstract

Electrohydrostatic actuators (EHA’s) are well-known for their high power densities (ratio of actuator weight to actuator power) and good dynamic performance. While EHA’s dominate in high-power systems, lower-powered systems (< 100W) typically employ electromechanical type actuators, such as screw actuators, due to the unavailability of low-cost hydraulic components on an appropriate scale. Recently, the radio-controlled hobby industry has started producing small- scale hydraulic pumps and cylinders for model construction equipment. These hobby grade pumps and cylinders may be repurposed in an EHA configuration for use in more demanding applications but limiting this is the fact that no appropriate method of handling the unbalanced cylinder flows of a typical single-rod cylinder exist. An inverse shuttle valve is a simple and efficient solution to compensate for this mismatch of cylinder flows, and the recent progression of 3D printed plastics enables such a valve to be produced for a very low cost. This thesis develops the small-scale 3D printed plastic inverse shuttle valve concept and improves upon prototypes developed within the Fluid Power Research Group at the University of Saskatchewan. Presented in this thesis is a wide variety of experiments investigating and improving the performance potential of such a 3D printed inverse shuttle valve in a small-scale EHA application. The sealing capabilities of 3D printed plastic poppets and the effects of print orientation, surface lapping, valve size, fluid pressure and sealing time were experimentally assessed. The pressure drops of the flow paths in a prototype design were measured and reduced by an informed selection of tubing and fittings. Finally, a series of experiments explored the steady state, dynamic response, and thermal performance of an EHA designed with the newly developed inverse shuttle valve. Satisfactory poppet sealing performance was obtained by utilizing a lapping procedure to smooth the sealing surfaces and selecting sealing element geometries insensitive to misalignment. A low- restriction flow path between the pump and valve was identified to improve power efficiency and reduce the potential for pump cavitation. Testing of the EHA revealed impressive performance, with high force and velocity capabilities, good energy efficiency, and very fast dynamic responses. These results satisfied the research objectives, demonstrating that the use of a 3D printed inverse shuttle valve in a small-scale EHA system is a viable concept.

Description

Keywords

Electrohydrostatic Actuator, EHA, hydraulics, 3D printing

Citation

Degree

Master of Science (M.Sc.)

Department

Mechanical Engineering

Program

Mechanical Engineering

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DOI

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