Span line pressure effect compensation for diaphragm pressure sensor

• US 9,316,553 B2
• Filed: 03/26/2014
• Issued: 04/19/2016
• Est. Priority Date: 03/26/2014
• Status: Active Grant

• Current Assignee: Rosemount Incorporated (Emerson Electric Company)
• Original Assignee: Rosemount Incorporated (Emerson Electric Company)
• Inventors: Willcox, Charles Ray
• Primary Examiner(s): Caputo, Lisa
• Assistant Examiner(s): PLUMB, NIGEL H
• Application Number:
  US14/225,763
• Publication Number:
  US 20150276528A1
• Time in Patent Office: 755 Days
• Field of Search: 737/18, 737/16, 737/17, 737/24, 737/53, 737/15, 73/92, 73/90, 737/00
• US Class Current: 1/1
• CPC Class Codes: G01L 19/02 Arrangements for preventing, or for compensating for, effects of inclination or acceleration of the measuring device; Zero-setting means for aneroid barometers G01L7/14
• CPC Class Codes: G01L 9/0041 Transmitting or indicating the displacement of flexible diaphragms
• CPC Class Codes: G01L 9/0072 using variations in capacitance

Abstract

A differential pressure sensor for sensing a differential pressure of a process fluid, includes a sensor body having a sensor cavity formed therein with a cavity profile. A diaphragm in the sensor cavity deflects in response to an applied differential pressure. The diaphragm has a diaphragm profile. A gap formed between the cavity profile and the diaphragm profile changes as a function of the differential pressure. At least one of the cavity profile and diaphragm profile changes as a function of a line pressure to compensate for changes in the gap due to deformation of the sensor body from the line pressure.

Claims

1. A differential pressure sensor for sensing a differential pressure of a process fluid, comprising:

a sensor body having a sensor cavity formed therein having a cavity profile; and

a diaphragm in the sensor cavity configured to deflect in response to an applied differential pressure, the diaphragm having a diaphragm profile wherein a gap between the cavity profile and the diaphragm profile changes as a function of the differential pressure;

wherein at least one of the cavity profile and diaphragm profile changes as a function of a line pressure, wherein the at least one of the cavity profile and diaphragm profile changes to compensate for changes in the gap due to radial deformation of the sensor body due to the line pressure and thereby reduce errors in differential pressure measurements due to the line pressure.

2. The differential pressure sensor of claim 1, wherein the sensor body includes a sensor body deformation cavity which deforms in response to the line pressure.

3. The differential pressure sensor of claim 2, including at least one vent port which couples to the sensor body deformation cavity.

4. The differential pressure sensor of claim 2, wherein the sensor body deformation cavity is annular.

5. The differential pressure sensor of claim 2, including a second sensor body deformation cavity.

6. The differential pressure sensor of claim 1, wherein the diaphragm includes a diaphragm deformation cavity which deforms in response to the line pressure.

7. The differential pressure sensor of claim 6, wherein the diaphragm deformation cavity is annular.

8. The differential pressure sensor of claim 6, including at least one vent port which couples to the diaphragm deformation cavity.

9. The differential pressure sensor of claim 1, including at least one capacitor electrode carried on the cavity profile.

10. The differential pressure sensor of claim 9, including measuring the differential pressure based upon a capacitance formed between at least one capacitor electrode and the diaphragm.

11. The differential pressure sensor of claim 1, including at least two annular capacitor plate electrodes carried on the sensor body profile.

12. The differential pressure sensor of claim 2, wherein the sensor body deformation cavity is larger in a radial direction.

13. The differential pressure sensor of claim 6, wherein the diaphragm deformation cavity is larger in a radial direction.

14. The differential pressure sensor of claim 1, wherein the diaphragm is fabricated of metal.

15. The differential pressure sensor of claim 1, wherein the diaphragm is fabricated of a ceramic.

16. The differential pressure sensor of claim 1, wherein the sensor body is fabricated of metal.

17. The differential pressure sensor of claim 1, wherein the sensor body is fabricated of an insulator.

18. The differential pressure sensor of claim 1, wherein the sensor body is fabricated of a metal and an insulator.

19. A method of sensing a differential pressure of a process fluid, comprising:

applying a first and second process pressure to a sensor body, the sensor body having a sensor cavity formed therein with a cavity profile;

placing a diaphragm in the sensor cavity of the sensor body configured to deflect in response to a pressure difference between the first applied pressure and the second applied pressure, the diaphragm having a diaphragm profile which forms a gap between the cavity profile and the diaphragm profile and wherein deflection of the diaphragm causes the gap to change as a function of the pressure difference;

compensating for differential pressure measurement inaccuracies due to a line pressure applied to the sensor body by changing at least one of the cavity profile and diaphragm profile as a function of the line pressure, and thereby reduce errors in differential pressure measurements due to the line pressure; and

measuring differential pressure based upon deflection of the diaphragm within the sensor body.

20. The method of claim 19, including forming a sensory body deformation cavity in the sensor body.

21. The method of claim 19, including forming a diaphragm deformation cavity in the diaphragm.