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US 4,850,805 AGranted
Pump control system
AssigneeCritikon, Inc.
InventorsKay Madsen, Frans Ludding
Life of this patent
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AssigneeCritikon, Inc.
InventorsKay Madsen, Frans Ludding
Estimating the term…
A pump control system is described in which the pumping mechanism causes corresponding movement of a pair of capacitor plates. The plates are energized by an a.c. signal, and the signal produced by the plates is amplitude detected, with the amplitude modulation representing pumping force. The pumping force is converted to pumping pressure. The pumping pressure peak during pumping and the pressure minimum during filling are detected to determine the portion of a pumping cycle required to make the transition between these two pressure levels. The difference between the two pressure levels divided by the transition portion of the pumping cycle gives a measure of the compliance of the pump chamber. The ratio of the compliance measure to the total cycle, when multiplied by the nominal chamber volume, gives a measure of unpumped volume, which is subtracted from the nominal volume to give the volume actually pumped during a pump cycle. The volume pumped is compared with a desired flow rate to determine a speed control value for the motor of the pumping mechanism. A motor control signal is developed by subtracting from a constant number a value which is a factor of the spaced control value and the position of the motor.
In a liquid pumping system, including a pump chamber which may exhibit compliance and which is operable in a filling cycle and in a pumping cycle, apparatus comprising:
A method for measuring the compliance of a liquid pumping chamber in which for displacing liquid is moved into and out of said chamber in alternating pumping and filling cycles comprising the steps of:
The method of claim 13, further comprising the step of:
A method of operating a liquid pumping system which includes a pump chamber having an inlet and an outlet, with a valve located at said outlet which opens upon the attainment of a given pressure level within said chamber, said pumping system being operable in a filling operation during which said chamber is filled with liquid, and in a pumping operation during which pressure is applied to the liquid within said chamber, comprising:
In a liquid pumping system, apparatus for controlling the speed of a continuous D.C. pump motor which is energized by a continuous D.C. voltage comprising:
Dependencies are inferred from the claim text.