Mathematical Modeling of a Two Spool Flow Control Servovalve Using a Pressure Control Pilot

[+] Author and Article Information
Randall T. Anderson, Perry Y. Li

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

J. Dyn. Sys., Meas., Control 124(3), 420-427 (Jul 23, 2002) (8 pages) doi:10.1115/1.1485287 History: Received February 01, 2001; Online July 23, 2002
Copyright © 2002 by ASME
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Anderson,  Wayne R., 1983, “Two Member Boost Stage Valve for a Hydraulic Control,” Tech. Rep. 4537220, US Patent.
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Li,  Perry Y., 2001, “Dynamic Redesign of a Flow Control Servovalve Using a Pressure Control Pilot,” Proceedings of the ASME. Dynamic Systems and Control Division, IMECE New York, NY, Vol. IMECE2001-DSC-24563; (published in this issue) ASME J. Dyn. Syst., Meas., Control, 124(3), pp. 428–434.
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Schematic of the two spool flow control valve using a pressure control pilot
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Signal flow and subsystem interconnection diagram of the valve
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Free body diagram of the armature-flapper
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Armature magnetic circuit. R1,R2 represent the variable air-gaps; Ra,Rb represent the fixed air-gaps. N⋅i and M0 are the MMF’s due to the input current and the permanent magnet, respectively.
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Free body diagram for spool A
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Flow paths when spools are displaced from null positions
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Schematic of the experimental setup
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Steady-state response. Top: flow Qa versus input current; bottom: flow Qa versus load pressures PL at various currents i.
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Step responses. Input steps are square waves with peaks of ±10 mA, ±20 mA, and ±30 mA.
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Frequency responses measured at 20 mA D.C. input superimposed by ±3 mA sinusoid. Top: magnitude plot, bottom: phase.




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