Pressure monitoring apparatus having a Hall-effect detector

• US 4,745,811 A
• Filed: 10/28/1985
• Issued: 05/24/1988
• Est. Priority Date: 10/28/1985
• Status: Expired due to Term

• Current Assignee: Entegris Incorporated
• Original Assignee: SPAN Instruments, Inc.
• Inventors: Gray, Tommy L.
• Primary Examiner(s): Woodiel, Donald O.
• Application Number:
  US06/792,150
• Time in Patent Office: 939 Days
• Field of Search: 73/733, 73/734, 73/735, 73/708, 73/741, 73/DIG. 3, 340/58, 340/688, 338/32 H
• US Class Current: 73/708
• CPC Class Codes: G01L 9/0029 using variations in inductance
• CPC Class Codes: G01L 9/14 involving the displacement of magnets, e.g. electromagnets

Abstract

A pressure responsive apparatus having a Hall-effect detector is described. The apparatus preferably includes a pressure gauge having a Bourdon tube responsive to an external pressure. The Bourdon tube has mounted thereto a pair of magnets supported on, or attached to, an end thereof for generating a low power, magnetic flux field. The Hall-effect detector is mounted in proximity to the pair of magnets and generates an output voltage having values corresponding to movement of the magnets with respect to the detector. A processing circuit receives the output voltage from the Hall-effect detector, and in response thereto generates a plurality of output signals proportional to the sensed pressure variations in the Bourdon tube.

Claims

1. A condition responsive apparatus, comprising:

a control member movable in response to variations in a physical condition;

magnetic means supported by said control member for movement therewith in response to said variations in the physical condition;

a Hall-effect detector mounted in proximity to said magnetic means for generating a signal proportional to movement of said magnetic means with respect to said detector; and

signal processing means including means for generating a temperature-compensating reference voltage, said processing means receiving the signal from said Hall-effect detector and the generated temperature compensated reference voltage and in response thereto generating at least one of the outputs, a floating voltage output, a ground referenced voltage output or a current output, each output proportional to variations in the external pressure.

2. A condition responsive apparatus, comprising:

a Bourdon tube having a free end movable in response to variations in an external pressure;

magnetic means mounted to the free end of said Bourdon tube for movement therewith in response to said variations in the external pressure;

a Hall-effect detector mounted in proximity to said magnetic means for generating a signal proportional to movement of said magnetic means with respect to said detector; and

signal processing means for receiving the signal from said Hall-effect detector and in response thereto generating at least one of the following outputs, a floating voltage output, a ground referenced voltage output, or a current output, each output varying proportional to variations in the external pressure.

3. The condition responsive apparatus as described in claim 2 wherein said magnetic means includes a pair of magnets for generating a low power, magnetic flux field proximate said Hall-effect detector.

4. A pressure responsive apparatus, comprising:

a pressure gauge having a Bourdon tube including a free end responsive to variations in an external pressure;

magnetic means mounted to the free end of said Bourdon tube for movement therewith in response to said variations in the external pressure;

a Hall-effect detector mounted in proximity to said magnetic means for generating a signal varying in accordance with movement of said magnetic means with respect to said detector; and

signal processing means for receiving said signal from said detector and in response thereto generating at least one of the following outputs, a floating voltage output, a ground referenced voltage output, or a current output, each output proportional to variations in the external pressure.

5. A condition responsive apparatus, comprising:

a control member movable in response to variations in a physical condition;

magnetic means supported by said control member for movement therewith in response to variations in the physical condition;

a Hall-effect detector mounted in proximity to said magnetic means for generating a signal proportional to movement of said magnetic means with respect to said detector; and

signal processing means including means for generating a temperature compensating reference voltage and means for comparing said temperature compensated reference voltage with the signal from said detector, and in response thereto generating at least one of the following outputs, a floating voltage output, a ground referenced voltage output, or a current output, each output proportional to variations in the physical condition.

6. The condition responsive apparatus as described in claim 5 wherein said signal processing means further includes means for comparing said temperature-compensated reference voltage with said floating voltage output, and in response thereto generating the ground referenced output voltage V₂ proportional to variations in the physical condition.

7. The condition responsive apparatus as described in claim 6 wherein said signal processing means further includes voltage-to-current conversion means for comparing an externally applied voltage and said ground referenced output voltage, and in response thereto generating the current output that varies proportional to variations in the physical condition.

8. The condition responsive apparatus as described in claim 7 wherein said voltage-to-current conversion means includes a comparator for receiving said external voltage and said ground referenced output voltage, and a current circuit to said comparator and having a pair of current resistors, wherein said current sinking resistors establishes a current in proportion to said ground referenced output voltage to generate said current output.

9. A pressure responsive apparatus, comprising:

a pressure gauge having a Bourdon tube responsive to variations in an external pressure;

a support assembly attached to said Bourdon tube for movement therewith in response to said variations in the external pressure;

a pair of magnets supported on said support assembly for generating a low power, magnetic flux field;

a Hall-effect detector mounted in proximity to said pair of magnets for generating a voltage having values corresponding to the movement of the pair of magnets with respect to said detector; and

a processing circuit for receiving said voltage from said Hall-effect detector and in response thereto generating a floating output voltage, a ground referenced output voltage and a current output proportional to variations in the external pressure.

10. The pressure responsive apparatus as described in claim 9 wherein said processing circuit includes:

a temperature compensation network for receiving a regulated supply voltage and in response thereto generating a temperature-compensated reference voltage; and

a comparator for comparing the voltage from said detector with the temperature-compensated reference voltage, and in response thereto generating the floating output voltage.

11. The pressure responsive apparatus as described in claim 10 wherein said processing circuit further includes:

a comparator for comparing the temperature-compensated reference voltage with the floating output voltage, and in response thereto generating the ground-referenced output voltage.

12. The pressure responsive apparatus as described in claim 11 wherein said processing circuit further includes:

a voltage-to-current converter for comparing an externally applied voltage with the ground-referenced output voltage, and in response thereto generating the current output.

13. A pressure responsive apparatus, comprising:

a pressure gauge having a Bourdon tube responsive to variations in an external pressure;

a pair of magnets attached to said Bourdon tube for movement therewith in response to variations in the external pressure;

a Hall-effect detector mounted in proximity to said pair of magnets for generating a voltage having values corresponding to movement of the pair of magnets with respect to said detector; and

a processing circuit, comprising;

means for generating a temperature-compensated reference voltage;

means for comparing the voltage from said Hall-effect detector with the temperature-compensated reference voltage, and in response thereto generating a first output voltage;

means for comparing the temperature-compensated reference voltage with the first output voltage, and in response thereto generating a second output voltage; and

means for comparing an externally applied voltage and the second output voltage, and in response thereto generating an output current;

wherein the first and second output voltages and the output current are proportional to the variations in the external pressure applied to said Bourdon tube.

14. The condition responsive apparatus as described in claim 13 wherein each of said magnets is formed of a rare earth material.

15. The pressure responsive apparatus as described in claim 13 wherein said means for generating a temperature-compensated reference voltage comprises a temperature compensation network including a temperature sensitive element and zero adjust resistor means for setting the reference voltage when zero pressure is applied to said pressure gauge.

16. The pressure responsive apparatus as described in claim 13 wherein said means for comparing the voltage from said detector with the temperature-compensated reference voltage includes a comparator having gain adjustment means for setting the first output voltage when full scale pressure is applied to said pressure gauge.