Valve timing and area profile selection for hydraulic pumps and motors

Grey C. Boyce-Erickson, Thomas R. Chase, James D. Van De Ven

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

A significant amount of research has been conducted to select valve timing and area profiles that create efficient and quiet hydraulic pumps and motors. Numerous active valve architectures have been modeled and optimized, but the rationale for the final solution is often unclear. The solution is usually highly dependent on the modeled valve geometry constraints and the duty cycle of the pump or motor for which the valve was optimized. In contrast, this paper proposes a methodology for designing efficient valving that is not constrained to any specific valve geometry, operating point, parameterization, or physical system limitation. An idealized valve area profile is formulated using a piston-cylinder model with variable valve openings. A working fluid that has a pressure dependent bulk modulus is utilized in the model. The valve timing is idealized by constraining it to produce a specified constant pressure drop across the valve. The idealized area profile is synthesized by modeling the piston-cylinder as a pump with passive (check) valves. A representation of the idealized timing is demonstrated for positive pressure differential and positive rotation direction, also known as the first quadrant. The effect of varying pressure on valve timing is shown for the first quadrant, but the trend can be extrapolated for all quadrants of operation. The idealized valve area profile is implemented as fixed valve timing in a pump-motor, meaning the valve area is only a function of the timing angle of the rotating group. Fixed valve timing is preferred to variable valve timing as it can often be implemented mechanically, increasing reliability. The pumpmotor is simulated in one rotation direction through a pressure range. Performance is high in pumping operation, but when the pressure differential is reversed, cylinder pressure spikes ensue. Two strategies to modify an idealized valve area profile are presented: timing grooves and a pressure shifted valve timing. Timing grooves reduce pressure spikes and cavitation in the cylinder but generally increase throttling losses. A pressure shifted valve timing has lower throttling energy losses, making it the favored solution.

Original languageEnglish (US)
Title of host publicationBATH/ASME 2020 Symposium on Fluid Power and Motion Control, FPMC 2020
PublisherAmerican Society of Mechanical Engineers
ISBN (Electronic)9780791883754
DOIs
StatePublished - 2020
EventBATH/ASME 2020 Symposium on Fluid Power and Motion Control, FPMC 2020 - Virtual, Online
Duration: Sep 9 2020Sep 11 2020

Publication series

NameBATH/ASME 2020 Symposium on Fluid Power and Motion Control, FPMC 2020

Conference

ConferenceBATH/ASME 2020 Symposium on Fluid Power and Motion Control, FPMC 2020
CityVirtual, Online
Period9/9/209/11/20

Bibliographical note

Funding Information:
This material is based upon work supported by the U.S. Department of Energy’s Office of Energy Efficiency and Renewable Energy (EERE) under the Vehicle Technologies Office Award Number DE-EE0008335.

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