Solenoid cassette pump with servo controlled volume detection

US6942469B2 · kind B2 · utility

Assignee

• Crystal Investments, Inc. · BB

Inventors

• Joseph B. Seale · Gorham, US
• Gary Bergstrom · Moreland Hills, US

Key dates

• Filing date: Jan 30, 2001
• Grant date: Sep 13, 2005
• Expiry date: Jan 30, 2021

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y02T10/12
• WIPO field: Engines, pumps, turbines
• WIPO sector: Mechanical engineering

Abstract

Servo controlled solenoids provide actuation of a pump piston and valves, and electronic LC resonance measurements to determine liquid volume and gas bubble volume. Third order nonlinear servo control is split into nested control loops: a fast nonlinear first-order inner loop causing flux to track a target by varying a voltage output, and a slower almost linear second-order outer loop causing magnetic gap to track a target by controlling the flux target or the inner loop. The inner loop uses efficient switching regulation, preferably based on controlled feedback instabilities, to control voltage output. The outer loop achieves damping and accurate convergence using proportional, time-integral, and time-derivative gain terms. The time-integral feedback may be based on measured and target solenoid drive currents, adjusting the magnetic gap for force balance at the target current.