Liquid level sensing and control

• US 4,744,808 A
• Filed: 10/30/1986
• Issued: 05/17/1988
• Est. Priority Date: 10/30/1986
• Status: Expired due to Term

• Current Assignee: Gambro, Inc. (DaVita Incorporated)
• Original Assignee: Cobe Cardiovascular Incorporated (LivaNova Plc)
• Inventors: Treu, Dennis M.
• Primary Examiner(s): SPITZER, ROBERT H
• Application Number:
  US06/925,736
• Time in Patent Office: 565 Days
• Field of Search: 55/160, 55/165-170, 55/208, 55/216, 55/219, 73/290 R, 73/308, 73/313, 137/173, 137/412, 340/624, 340/618, 340/623
• US Class Current: 96/158
• CPC Class Codes: B01D 19/0063 Regulation, control including valves and floats for construction and details of valves F16K
• CPC Class Codes: G01F 23/74 for sensing changes in level only at discrete points
• CPC Class Codes: Y10T 137/7368 Servo relay operation of control

Abstract

A fluid flow chamber including a housing defining a chamber, a chamber inlet and a chamber outlet for flow of liquid therethrough, a float in the chamber, and a magnet and magnetic position sensor, one of which is carried by the float for movement with the change in liquid level in the chamber, the other of which is fixedly mounted with respect to the housing.

Claims

1. A fluid flow chamber and a controller for flow therethrough comprising

a housing defining a chamber, a chamber inlet and a chamber outlet for flow of liquid therethrough,

a float in said chamber,

a magnet,

a magnetic position sensor that provides an output signal with a magnitude related to the strength of a magnetic field to which it is subjected,

one of said magnet and magnetic position sensor being carried by said float for movement with the change in liquid level in said chamber,

the other of said magnet and magnetic position sensor being fixedly mounted with respect to said housing,

said magnet being oriented with respect to said sensor so as to subject said sensor to a magnetic field that continuously varies in strength as a function of level of liquid in said chamber,

thereby causing an output signal at said sensor that continuously varies in magnitude as a function of level,

an actuator hydraulically connected to said chamber so as to affect flow through said chamber, and

an electronic controller connected to receive said output signal of said sensor and to provide a control signal to said actuator based upon the magnitude of said output signal.

2. The fluid flow chamber and controller of claim 1 further comprising a vertically oriented guide support along which said float travels as the liquid level in said chamber rises and falls.

3. The chamber and controller of claim 2 wherein said float has an opening through which said guide support passes.

4. The chamber and controller of claim 3 wherein said magnetic position sensor is carried by said guide support, and there are two magnets carried by said float on opposite sides of said magnetic position sensor.

5. The chamber and controller of claim 4 wherein said magnets have north and south poles vertically oriented with respect to each other and spaced from each other by a gap between them along vertical axes, and one said magnet has its north pole on the top, and the other said magnet has its north pole on the bottom.

6. The chamber and controller of claim 4 wherein said magnets are each made of individual magnetic elements mounted on a vertically oriented shunt bar, one said individual magnetic element having its north pole against a said shunt bar and the other said individual magnetic element having its south pole against said shunt bar.

7. The chamber and controller of claim 3 wherein said guide support has stop members larger in size than said opening to retain said float between them.

8. The chamber and controller of claim 2 wherein said guide support is mounted at the top of said housing.

9. The chamber of claim 1 wherein said chamber and controller has a gas outlet at the top of said housing for removing gas volatilized from said liquid.

10. The chamber and controller of claim 9 further comprising a divider in said chamber dividing it into a deaeration zone including said float and an upstream heater zone.

11. The chamber and controller of claim 1 wherein said actuator comprises a valve that controls flow into said inlet, and wherein said control signal controls a duty cycle of said valve so as to be open a portion of the duty cycle depending upon the liquid level indicated by the magnitude of said output signal.

12. A fluid flow chamber comprising

a housing defining a chamber, a chamber inlet and a chamber outlet for flow of liquid therethrough,

a float in said chamber,

a magnet,

a magnetic position sensor that provides an output signal with a magnitude related to the strength of a magnetic field to which it is subjected,

one of said magnet and magnetic position sensor being carried by said float for movement with the change in liquid level in said chamber,

the other of said magnet and magnetic position sensor being fixedly mounted with respect to said housing,

said magnet being oriented with respect to said sensor so as to subject said sensor to a magnetic field that continuously varies in strength as a function of level of liquid in said chamber,

thereby causing an output signal at said sensor that continuously varies in magnitude as a function of level,

said magnet having its north and south poles vertically oriented with respect to each other and spaced from each other by a gap between them along a vertical axis.

13. The chamber of claim 12 wherein there are two said magnets, one on each side of said sensor, and wherein one said magnet has its north pole on the top, and the other said magnet has its north pole on the bottom.