0
Research Papers

Design and Validation of a Soft Switch for a Virtually Variable Displacement Pump

[+] Author and Article Information
Brandon K. Beckstrand

Department of Mechanical Engineering,
University of Minnesota,
111 Church Street SE,
Minneapolis, MN 55455
e-mail: becks033@umn.edu

James D. Van de Ven

Department of Mechanical Engineering,
University of Minnesota,
111 Church Street SE,
Minneapolis, MN 55455
e-mail: vandeven@umn.edu

Contributed by the Dynamic Systems Division of ASME for publication in the JOURNAL OF DYNAMIC SYSTEMS, MEASUREMENT, AND CONTROL. Manuscript received September 23, 2015; final manuscript received September 27, 2017; published online December 22, 2017. Assoc. Editor: Umesh Vaidya.

J. Dyn. Sys., Meas., Control 140(6), 061006 (Dec 22, 2017) (11 pages) Paper No: DS-15-1460; doi: 10.1115/1.4038536 History: Received September 23, 2015; Revised September 27, 2017

Switch-mode hydraulic control is a compact and theoretically efficient alternative to throttling valve control or variable displacement pump control. However, a significant source of energy loss in switch-mode circuits is due to throttling during valve transitions. Hydraulic soft switching was previously proposed as a method of reducing the throttling energy loss, by absorbing, in a small variable volume chamber, the flow that would normally be throttled across the transitioning high-speed valve. An active locking mechanism was previously proposed that overcomes the main challenge with soft switching, which is a lock mechanism that releases quickly and with precise timing. This prior work demonstrated a reduction in energy losses by 66% compared to a control circuit. In this paper, a numerical model is developed for a switch-mode virtually variable displacement pump (VVDP) circuit, utilizing the proposed soft switch. The model is then used as a means of designing a proof of concept prototype to validate the model. The prototype design includes methods for controlling the soft switch spring preload, travel distance, piston displacement required to unlock the soft switch, valve command duty cycle, switching cycle period, and load pressure. Testing demonstrated that the soft switch circuit performed as expected in a baseline condition. The operating region for this prototype was found to be quite narrow. However, the model does a good job of predicting the displacement of the soft switch.

Copyright © 2018 by ASME
Your Session has timed out. Please sign back in to continue.

References

Li, P. Y. , Li, C. Y. , and Chase, T. R. , 2005, “ Software Enabled Variable Displacement Pumps,” ASME Paper No. IMECE2005-81376.
Mohan, N. , Undeland, T. M. , and Robbins, W. P. , 2003, Power Electronics: Converters, Applications, and Design, Wiley, Hoboken, NJ, pp. 161–178.
Rannow, M. B. , Tu, H. C. , Li, P. Y. , and Chase, T. R. , 2006, “ Software Enabled Variable Displacement Pumps: Experimental Studies,” ASME Paper No. IMECE2006-14973.
Batdorff, M. A. , and Lumkes, J. H. , 2006, “ Virtually Variable Displacement Hydraulic Pump Including Compressability and Switching Losses,” ASME Paper No. IMECE2006-14838.
Lumkes, J. H. , Batdorff, M. A. , and Mahrenholz, J. R. , 2009, “ Model Development and Experimental Analysis of a Virtually Variable Displacement Pump System,” Int. J. Fluid Power, 10(3), pp. 17–27. [CrossRef]
Cao, J. , Gu, L. , Wang, F. , and Qiu, M. , 2005, “ Switchmode Hydraulic Power Supply Theory,” ASME Paper No. IMECE2005-79019.
Tu, H. C. , Rannow, M. B. , Van de Ven, J. D. , Wang, M. , Li, P. Y. , and Chase, T. R. , 2007, “ High Speed Rotary Pulse Width Modulated On/Off Valve,” ASME Paper No. IMECE2007-42559.
Rannow, M. B. , and Li, P. Y. , 2012, “ Soft Switching Approach to Reducing Transition Losses in an On/Off Hydraulic Valve,” ASME J. Dyn. Sys. Meas. Control, 134(6), p. 064501. [CrossRef]
Van de Ven, J. , 2014, “ Soft Switch Lock-Release Mechanism for a Switch-Mode Hydraulic Pump Circuit,” ASME J. Dyn. Sys. Meas. Control, 136(3), p. 031003. [CrossRef]
Cho, B.-H. , Lee, H.-W. , and Oh, J.-S. , 2002, “ Estimation Technique of Air Content in Automatic Transmission Fluid by Measuring Effective Bulk Modulus,” KSAE Int. J. Autom. Technol., 3(2), pp. 57–61. http://www.dbpia.co.kr/Journal/ArticleDetail/NODE00525535
Çengel, Y. A. , and Cimbala, J. M. , 2010, Fluid Mechanics: Fundamentals and Applications, McGraw-Hill, New York.
Chapra, S. C. , and Canale, R. P. , 2006, Numerical Methods for Engineers, McGraw-Hill, New York, pp. 16–17.
ISO, 1992, “ Industrial Liquid Lubricants—ISO Viscosity Classification,” International Organization for Standardization, Geneva, Switzerland, Standard No. ISO 3448:1992. https://www.iso.org/standard/8774.html
Yudell, A. C. , and Van de Ven, J. D. , 2015, “ Predicting Solenoid Valve Spool Displacement Through Current Analysis,” Int. J. Fluid Power, 16(3), pp. 133–140.

Figures

Grahic Jump Location
Fig. 4

Three-way valve orifice area as a function of time, with a 60% duty cycle and a period of 0.15 s

Grahic Jump Location
Fig. 2

Virtually variable displacement pumping circuit

Grahic Jump Location
Fig. 1

Soft switch concept as proposed by Van de Ven (Adapted from Ref. [9])

Grahic Jump Location
Fig. 5

Open area of check valves corresponds to the dotted cylindrical surface area between the check valve disk and seat

Grahic Jump Location
Fig. 6

Open area of the soft switch internal port to tank. The port is comprised of 6 radial holes through the cylinder sleeve.

Grahic Jump Location
Fig. 3

Graphical representation of high-speed valve spool displacement relative to tank and load port openings

Grahic Jump Location
Fig. 8

Numerical model performance plots, showing the behavior of the soft switch for one complete switching cycle

Grahic Jump Location
Fig. 9

Cross-sectional view of the assembled soft switch, including three-way control valve and manifold

Grahic Jump Location
Fig. 10

Soft switch test bed setup with component labels

Grahic Jump Location
Fig. 11

The soft switch hydraulic test circuit layout. Three pressure transducers and two flow meters gathered pertinent information regarding system behavior.

Grahic Jump Location
Fig. 7

Leakage flow paths past the soft switch piston. The path represented by the dotted line goes from the switched volume at the front of the piston to the volume behind the piston. The path represented by the dashed lines travel from the back of the soft switch to tank via two paths, as a result of the internal porting of the piston.

Grahic Jump Location
Fig. 14

Experimentally measured high and low system load pressure cases resulting in operation failure: (a) high load pressure of 5.72 MPa and (b) low load pressure of 5.52 MPa

Grahic Jump Location
Fig. 15

Experimentally measured high and low valve switching period cases resulting in operation failure: (a) high valve switching period of 0.152 s and (b) low valve switching period of 0.138 s

Grahic Jump Location
Fig. 16

Comparison between the experimental measurements and the numerical model for the baseline case

Grahic Jump Location
Fig. 17

Comparison between the experimental measurements and the numerical model for the high switching period case. The switched volume pressure is not accurately predicted due to slow unlocked piston movement.

Grahic Jump Location
Fig. 12

Experimentally measured switched volume pressure profile for control case with the soft switch locked. The switched volume pressure spike reaches 9.02 MPa.

Grahic Jump Location
Fig. 13

Experimentally measured soft switch piston displacement and pressure profiles for baseline parameters

Tables

Errata

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