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Electropermanent magnetic (EPM) valves consist of two permanent magnets, one with high coercivity and one with relatively low coercivity, which are able to rapidly redirect the flux within a magnetic circuit. When combined with magnetorheological (MR) fluid, they provide the ability to rapidly switch flow in a hydraulic circuit on or off. EPM valves contain no moving parts and draw no power except when changing state. These facts, along with their scalability, make them an attractive option for distributed flow control in small hydraulic systems. Current examples of EPM valves are often restricted to relatively low-pressure or low-flow operation. Miniaturization of small-scale hydraulic robots, both soft and rigid, is limited by the availability of sufficiently lightweight, compact, and efficient components which are capable of directing fluid at pressures greater than 700 kPa. This research proposes an EPM valve which leverages the magnetic properties of MR fluid to channel magnetic flux through the fluid. To evaluate the proposed geometry, an exploratory prototype was constructed and evaluated using a test-bench capable of evaluating the valve as a flow resistance. Simulations were conducted to evaluate the design and validate the use of simulation for future design iteration. To be of use in robotic systems, this valve needs to be capable of rapidly switching relatively high pressures while maintaining a highly compact and easily manufactured form factor. Due to its size and low power consumption, it is suitable for distributed hydraulic control in miniature systems such as hydraulically-actuated robots, including soft robots.
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Compressible Flow Through Flat Valve Seals at Microscale Displacements
Abstract Existing analytical flow models for predicting flow rates at microscale seal displacements are limited to two separate domains. The first assumes a small channel length to height aspect ratio at relatively large seal displacements. The second assumes a large channel length to height aspect ratio at relatively small seal displacements. A piecewise analytical model for compressible flow is developed here to enable predicting flow rates in valves with fluid pathways of any aspect ratio. The new model is validated by numerical studies and experiment. The results are applicable to flat valve seals having a cylindrical seal boss feature with fluid passage length to height aspect ratios ranging from 3.3 to 800. The new model is particularly useful for the design of microvalves and macroscale valves with small actuator displacements.
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- Award ID(s):
- 2016330
- PAR ID:
- 10569924
- Publisher / Repository:
- American Society of Mechanical Engineers (ASME)
- Date Published:
- Journal Name:
- Journal of Fluids Engineering
- Volume:
- 146
- Issue:
- 11
- ISSN:
- 0098-2202
- Subject(s) / Keyword(s):
- compressible flow flow modeling flow control valve
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1115/1.4065383
