Research Papers

Adjustable Linkage Pump: Efficiency Modeling and Experimental Validation

[+] Author and Article Information
Shawn Wilhelm

Department of Mechanical Engineering,
University of Minnesota,
111 Church St. SE,
Minneapolis, MN 55455

James Van de Ven

Assistant Professor
Department of Mechanical Engineering,
University of Minnesota,
111 Church St. SE,
Minneapolis, MN 55455

1Corresponding author.

Contributed by the Mechanisms and Robotics Committee of ASME for publication in the JOURNAL OF MECHANISMS AND ROBOTICS. Manuscript received February 3, 2014; final manuscript received July 30, 2014; published online December 4, 2014. Assoc. Editor: Philippe Wenger.

J. Mechanisms Robotics 7(3), 031013 (Aug 01, 2015) (8 pages) Paper No: JMR-14-1027; doi: 10.1115/1.4028293 History: Received February 03, 2014; Revised July 30, 2014; Online December 04, 2014

Variable displacement pumps are a key component to a variety of mobile and industrial hydraulic systems, yet the efficiency of existing pump architectures is poor at low displacement. As a solution to this issue, a new pump architecture is proposed that eliminates the planar hydrodynamic joints of a conventional architecture with rolling-element pin joints in an adjustable linkage. This new architecture uses an adjustable six-bar linkage that reaches true zero displacement and has the same top-dead-center (TDC) position regardless of displacement. In this work, the linkage kinematics and dynamics are discussed, an energy loss model is developed and used to drive design decisions of a first generation prototype, and experimental results are presented to validate the model. It is shown that this linkage-based, variable, positive displacement architecture shows promise as a highly efficient alternative to existing pump architectures across a wide range of displacements.

Copyright © 2015 by ASME
Your Session has timed out. Please sign back in to continue.


Love, L., Lanke, E., and Alles, P., 2012, Estimating the Impact (Energy, Emissions and Economics) of the U.S. Fluid Power Industry, Oak Ridge National Laboratory (ORNL), Oak Ridge, TN.
Salter, S., and Rea, M., 1984, “Hydraulics for Wind,” European Wind Energy Conference, Hamburg, Germany, Oct. 22–26, pp. 534–541.
Van de Ven, J. D., Olson, M. W., and Li, P. Y., 2008, “Development of a Hydro-Mechanical Hydraulic Hybrid Drive Train With Independent Wheel Torque Control for an Urban Passenger Vehicle,” National Conference on Fluid Power, Las Vegas, NV, Mar. 11–15, pp. 503–514.
Comellas, M., Pijuan, J., Potau, X., Nogués, M., and Roca, J., 2013, “Efficiency Sensitivity Analysis of a Hydrostatic Transmission for an Off-Road Multiple Axle Vehicle,” Int. J. Automot. Technol., 14(1), pp. 151–161. [CrossRef]
Williamson, C., Zimmerman, J., and Ivantysynova, M., 2008, “Efficiency Study of an Excavator Hydraulic System Based on Displacement-Controlled Actuators,” Bath/ASME Symposium on Fluid Power and Motion Control, Bath, UK, Sept. 10–12, pp. 291–307.
Wieczorek, U., and Ivantysynova, M., 2002, “Computer Aided Optimization of Bearing and Sealing Gaps in Hydrostatic Machines: The Simulation Tool CASPAR,” Int. J. Fluid Power, 3(1), pp. 7–20. [CrossRef]
Manring, N. D., 2003, “Valve-Plate Design for an Axial Piston Pump Operating at Low Displacements,” ASME J. Mech. Des., 125(1), pp. 200–205. [CrossRef]
Inaguma, Y., and Hibi, A., 2007, “Reduction of Friction Torque in Vane Pump by Smoothing Cam Ring Surface,” Proc. Inst. Mech. Eng., Part C, 221(5), pp. 527–534. [CrossRef]
Rannow, M., Tu, H., Li, P. Y., and Chase, T., 2006, “Software Enabled Variable Displacement Pumps: Experimental Studies,” ASME Paper No. IMECE2006-14973. [CrossRef]
Tu, H., Rannow, M. B.,Wang, M., Li, P. Y., and Chase, T. R., 2009, “Modeling and Validation of a High Speed Rotary PWM On/Off Valve,” ASME Paper No. DSCC2009-2763. [CrossRef]
M.Wang, Li, P. Y., Chase, T. R., and Van de Ven, J. D., 2012, “Design, Modeling, and Validation of a High-Speed Rotary Pulse-Width-Modulation On/Off Hydraulic Valve,” ASME J. Dyn. Syst. Meas. Control, 134(6), p. 061002. [CrossRef]
Ehsan, M., Rampen, W., and Salter, S., 2000, “Modeling of Digital-Displacement Pump-Motors and Their Application as Hydraulic Drives for Nonuniform Loads,” ASME J. Dyn. Syst. Meas. Control, 122(1), pp. 210–215. [CrossRef]
Linjama, M., 2011, “Digital Fluid Power: State of the Art,” 12th Scandinavian International Conference on Fluid Power, Tampere, Finland, May 18–20, pp. 331–353.
Yigen, C., 2012, “Control of a Digital Displacement Pump,” Masters thesis, Department of Energy Technology, Aalborg University, Aalborg, Denmark.
Pierce, J., 1914, “Variable Stroke Mechanism,” U.S. Patent No. 1,112,832.
Pouliot, H. N., Delameter, W. R., and Robinson, C. W., 1977, “A Variable Displacment Spark-Ignition Engine,” SAE Paper No. 770114. [CrossRef]
Nelson, C. D., 1985, “Variable Stroke Engine,” U.S. Patent No. 4517931.
Yamin, J. A. A., and Dado, M. H., 2004, “Performance Simulation of a Four-Stroke Engine With Variable Stroke-Length and Compression Ratio,” Appl. Energy, 77(4), pp. 447–463. [CrossRef]
Freudenstein, F., and Maki, E. R., 1983, “Development of an Optimum Variable-Stroke Internal-Combustion Engine Mechanism From the Viewpoint of Kinematic Structure,” ASME J. Mech. Transm. Autom. Des., 105(2), pp. 259–266. [CrossRef]
Freudenstein, F., and Maki, E., 1984, “Kinematic Structure of Mechanisms for Fixed and Variable-Stroke Axial-Piston Reciprocating Machines,” ASME J. Mech. Transm. Autom. Des., 106(3), pp. 355–364. [CrossRef]
Freudenstein, F., and Maki, E. R., 1981, “Variable Displacement Piston Engine,” U.S. Patent No. 4270495.
Wilhelm, S., and Van de Ven, J. D., 2011, “Synthesis of a Variable Displacement Linkage for a Hydraulic Transformer,” ASME Paper No. DETC2011-47339. [CrossRef]
Wilhelm, S. R., and Van de Ven, J. D., 2013, “Design and Testing of an Adjustable Linkage for a Variable Displacement Pump,” ASME J. Mech. Rob., 5(4), p. 041008. [CrossRef]
Norton, R. L., 2008, Design of Machinery: An Introduction to the Synthesis and Analysis of Mechanisms and Machines, McGraw-Hill, Boston.
Ivantysyn, J., and Ivantysynova, M., 2001, Hydrostatic Pumps and Motors, Academic Books International, New Dehli, India.
Beardmore, R., 2013, “ROYMECH Friction Factors,” accessed Nov. 26, 2013, http://www.roymech.co.uk/Useful_Tables/Tribology/co_of_frict.htm
Beardmore, R., 2010, “Roller Bearing Friction,” accessed Nov. 23, 2012, http://www.roymech.co.uk/Useful_Tables/Tribology/Bearing%20Friction.html


Grahic Jump Location
Fig. 1

Schematic of the adjustable linkage

Grahic Jump Location
Fig. 2

Vector loop diagram of linkage for position analysis

Grahic Jump Location
Fig. 3

Free body diagram of the moving components of the linkage showing forces and centers of mass

Grahic Jump Location
Fig. 4

Coulomb friction diagram showing pin joints relative to various links

Grahic Jump Location
Fig. 5

Prototype variable displacement linkage pump used for low power experimental validation

Grahic Jump Location
Fig. 6

(a) Hydraulic circuit diagram displaying the experimental setup. (b) Image of the experimental setup showing the prototype.

Grahic Jump Location
Fig. 7

Work output experimental data plotted against model at various frequencies and pressures

Grahic Jump Location
Fig. 8

Work input experimental data plotted against model at various frequencies and pressures

Grahic Jump Location
Fig. 9

Contributions of various loss terms as a function of displacement at 2.4 MPa and 3 Hz of present design

Grahic Jump Location
Fig. 10

Contour plot of model efficiency at constant pressure and varying system frequencies of present design

Grahic Jump Location
Fig. 11

Contour plot of model efficiency at constant pumping frequency and varying pressures of present design

Grahic Jump Location
Fig. 12

Efficiency curve versus displacement for a pump with rolling element bearings at 21 MPa and 30 Hz




Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Related Journal Articles
Related eBook Content
Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In