Software enabled variable displacement pumps - Experimental studies

Michael B. Rannow, Haink C. Tu, Perry Y. Li, Thomas R. Chase

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

29 Scopus citations


The majority of hydraulic systems are controlled using a metering valve or the use of variable displacement pumps. Metering valve control is compact and has a high control bandwidth, but it is energy inefficient due to throttling losses. Variable displacement pumps are far more efficient as the pump only produces the required flow, but comes with the cost of additional bulk, sluggish response, and added cost. In a previous paper [1], a hydromechanical analog of an electronic switch-mode power supply was proposed to create the functional equivalent of a variable displacement pump. This approach combines a fixed displacement pump with a pulse-width-modulated (PWM) on/off valve, a check valve, and an accumulator. The effective pump displacement can be varied by adjusting the PWM duty ratio. Since on/off valves exhibit low loss when fully open or fully closed, the proposed system is potentially more energy efficient than metering valve control, while achieving this efficiency without many of the shortcomings of traditional variable displacement pumps. The system also allows for a host of programmable features that can be implemented via control of the PWM duty ratio. This paper presents initial experimental validation of the concept as well as an investigation of the system efficiency. The experimental apparatus was built using available off-the-shelf components and uses a linear proportional spindle valve as the PWM valve. Experimental results confirm that the proposed approach can achieve variable control function more efficiently than a valve controlled system, and that by increasing the PWM frequency and adding closed-loop control can decrease system response times and of the output ripple magnitude. Sources of inefficiency and their contributions are also investigated via modeling, simulation and are validated by experiments. These indicate design parameters for improving inefficiency.

Original languageEnglish (US)
Title of host publicationProceedings of 2006 ASME International Mechanical Engineering Congress and Exposition, IMECE2006 - Fluid Power Systems and Technology Division
PublisherAmerican Society of Mechanical Engineers (ASME)
ISBN (Print)0791837904, 9780791837900
StatePublished - 2006
Event2006 ASME International Mechanical Engineering Congress and Exposition, IMECE2006 - Chicago, IL, United States
Duration: Nov 5 2006Nov 10 2006

Publication series

NameAmerican Society of Mechanical Engineers, The Fluid Power and Systems Technology Division, FPST
ISSN (Print)1071-6947


Conference2006 ASME International Mechanical Engineering Congress and Exposition, IMECE2006
Country/TerritoryUnited States
CityChicago, IL


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