Pressure sensor with deflectable diaphragm

• US 7,415,886 B2
• Filed: 12/20/2005
• Issued: 08/26/2008
• Est. Priority Date: 12/20/2005
• Status: Active Grant

• Current Assignee: Rosemount Incorporated (Emerson Electric Company)
• Original Assignee: Rosemount Incorporated (Emerson Electric Company)
• Inventors: Klosinski, Andrew, Schumacher, Mark
• Primary Examiner(s): Allen; Andre J
• Application Number:
  US11/312,062
• Publication Number:
  US 20070151349A1
• Time in Patent Office: 980 Days
• Field of Search: 737/18, 737/24
• US Class Current: 73/718
• CPC Class Codes: G01L 13/025 using diaphragms
• CPC Class Codes: G01L 9/0075 using a ceramic diaphragm, e.g. alumina, fused quartz, glass

Abstract

A pressure sensor for sensing a pressure of a process fluid includes a sensor body having a cavity formed therein. A deflectable diaphragm is positioned in the cavity and deflects in response to a pressure applied to the cavity. An electrode on the diaphragm forms a variable capacitor with the pressure sensor body. The capacitance varies in response to the applied pressure.

Claims

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

a sensor body having a cavity formed therein;

a pressure connection extending through the cavity into the body;

a deflectable diaphragm in the cavity configured to deflect in response to a pressure applied to the cavity through the pressure connection;

an electrode carried by the diaphragm configured to form a variable capacitor with the pressure sensor body having a capacitance which varies in response to the applied pressure; and

an electrical connection to the electrode which extends to outside of the pressure sensor body wherein the sensor body is formed from two sensor body halves.

2. The apparatus of claim 1 wherein the deflectable diaphragm comprises a rigid material.

3. The apparatus of claim 1 wherein the deflectable diaphragm comprises a crystal material.

4. The apparatus of claim 1 wherein the deflectable diaphragm comprises a material selected from the group of materials consisting of silicon, quartz, sapphire and spinel.

5. The apparatus of claim 1 wherein the sensor body comprises a conductive material.

6. The apparatus of claim 1 wherein the sensor body comprises a metal.

7. The apparatus of claim 1 wherein the diaphragm is formed from two diaphragms halves.

8. The apparatus of claim 1 including a second electrode carried by the diaphragm configured to form a second variable capacitor with the pressure sensor body.

9. The apparatus of claim 8 wherein the electrode and the second electrode are on opposite sides of the diaphragm.

10. The apparatus of claim 1 wherein two electrodes are positioned on one side of the diaphragm and two electrodes are positioned on an opposite side of the diaphragm.

11. The apparatus of claim 1 wherein the diaphragm includes an internal diaphragm cavity configured to deform in response to a line pressure applied to the cavity of the sensor body.

12. The apparatus of claim 11 wherein the internal diaphragm cavity includes electrodes configured to form a variable capacitance which changes based upon the applied line pressure.

13. The apparatus of claim 1 wherein the cavity of the sensor body receives a differential pressure and deflection of the diaphragm is based upon the differential pressure.

14. The apparatus of claim 1 including a temperature sensor configured to measure a temperature of the sensor body or diaphragm.

15. The apparatus of claim 1 including a protrusion from the diaphragm which carries the electrical connections from the diaphragm to outside of the pressure sensor body.

26. The apparatus of claim 1 wherein the deflectable diaphragm comprises an insulator.

28. The apparatus of claim 1 wherein the electrode is deposited on a surface of the diaphragm.

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

providing an electrode carried by a deflectable diaphragm;

placing the deflectable diaphragm in a sensor body;

applying a pressure to the deflectable diaphragm through the sensor body to thereby cause deflection;

measuring changes in a capacitance between the electrode on the deflectable diaphragm and the sensor body; and

determining pressure based upon changes in the measured capacitance wherein the sensor body is formed from two sensor body halves.

17. The method of claim 16 wherein the deflectable diaphragm comprises a rigid material.

18. The method of claim 16 wherein the deflectable diaphragm comprises a crystal material.

19. The method of claim 16 wherein the deflectable diaphragm comprises a material selected from the group of materials consisting of silicon, quartz, sapphire and spinel.

20. The method of claim 16 wherein the sensor body comprises a conductive material.

21. The method of claim 16 wherein the diaphragm is formed from two diaphragms halves.

22. The method of claim 16 including providing a second electrode on the diaphragm configured to form a second variable capacitor with the pressure sensor body.

23. The method of claim 16 including forming a diaphragm internal cavity in the diaphragm configured to deform in response to a line pressure applied to the cavity of the sensor body.

24. The method of claim 23 including providing electrodes in the diaphragm internal cavity configured to form a variable capacitance which changes based upon the applied line pressure.

25. The method of claim 16 including providing a temperature sensor configured to measure a temperature of the sensor body or diaphragm.

27. The method of claim 16 wherein the deflectable diaphragm comprises an insulator.

29. The method of claim 16 including depositing the electrode on a surface of the diaphragm.