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

Brandon K. Beckstrand, James D Van De Ven

Research output: Contribution to journalArticle

Abstract

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.

Original languageEnglish (US)
Article number061006
JournalJournal of Dynamic Systems, Measurement and Control, Transactions of the ASME
Volume140
Issue number6
DOIs
StatePublished - Jun 1 2018

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switches
Switches
Pumps
pumps
throttling
Energy dissipation
Networks (circuits)
energy dissipation
prototypes
hydraulic control
Piston displacement
Hydraulics
control valves
cycles
commands
pistons
hydraulics
travel
locking
Numerical models

Cite this

Design and Validation of a Soft Switch for a Virtually Variable Displacement Pump. / Beckstrand, Brandon K.; Van De Ven, James D.

In: Journal of Dynamic Systems, Measurement and Control, Transactions of the ASME, Vol. 140, No. 6, 061006, 01.06.2018.

Research output: Contribution to journalArticle

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