Pressure sensor assembly structure to insulate a pressure sensing device from harsh environments

• US 6,439,055 B1
• Filed: 11/15/1999
• Issued: 08/27/2002
• Est. Priority Date: 11/15/1999
• Status: Expired due to Term

• Current Assignee: Weatherford Technology Holdings, LLC (Weatherford International PLC)
• Original Assignee: Weatherford/Lamb Incorporated (Weatherford International PLC)
• Inventors: Talmadge, George J., Daigle, Guy, Chipman, Christopher T., Niezgorski, Richard M., Currier, Bradley A., Maron, Robert J., Gumprecht, Peter
• Primary Examiner(s): OEN, WILLIAM L
• Application Number:
  US09/440,555
• Time in Patent Office: 1,016 Days
• Field of Search: 356/4.09, 356/32, 356/345, 250/227.14, 250/227.18, 250/227.19, 250/227.21, 250/227.23, 250/227.27, 250/237.R, 250/237.G, 737/05, 738/00, 737/06, 367/149, 367/154, 367/166, 367/169, 367/171
• US Class Current: 73/705
• CPC Class Codes: E21B 47/013 Devices specially adapted for supporting measuring instruments on drill bits
• CPC Class Codes: E21B 47/06 Measuring temperature or pressure
• CPC Class Codes: E21B 47/135 using light waves, e.g. infrared or ultraviolet waves
• CPC Class Codes: G01L 11/025 using a pressure-sensitive optical fibre
• CPC Class Codes: G01L 9/06 of piezo-resistive devices

Abstract

A pressure sensor assembly for determining the pressure of a fluid in a harsh environment includes a pressure sensor suspended within a fluid filled housing. The assembly includes a pressure transmitting device which transmits the pressure of the fluid to sensor and maintains the fluid within the housing in a void free condition. The pressure sensor assembly maintains the sensor in a near zero base strain condition and further protects the sensor from shock and vibration. The pressure sensor assembly further includes bumpers that limit the movement of the sensor within the housing.

Claims

1. A pressure sensor assembly for measuring a pressure of a first fluid, comprising:

a housing containing a second fluid;

a fiber optic-based pressure sensing element disposed in the second fluid within the housing; and

a pressure transmission device coupled to the housing and disposed in contact with the first fluid, wherein the pressure transmission device transmits the pressure of the first fluid to the second fluid and maintains the second fluid at a predetermined minimum pressure.

2. The pressure sensor assembly of claim 1, wherein the sensing element floats within the second fluid within the housing.

3. The pressure sensor assembly of claim 2, wherein the predetermined minimum pressure is sufficient to maintain the sensing element at a near zero base strain condition.

4. The pressure sensor assembly of claim 1, wherein the pressure transmission device comprises a bellows.

5. The pressure sensor assembly of claim 1, wherein the pressure transmission device comprises a pressure sensitive valve.

6. The pressure sensor assembly of claim 1, wherein the pressure transmission device comprises an inlet tube having a predetermined inside diameter.

7. The pressure sensor assembly of claim 1, wherein the pressure transmission device comprises a diaphragm.

8. The pressure sensor assembly of claim 1, further comprising a tube in fluid communication with the first fluid.

9. The pressure sensor assembly of claim 1, wherein the pressure sensor assembly further comprises:

a seal disposed in the housing; and

a signal transmission cable coupled to the sensing element and extending through the seal to the outside of the housing.

10. The pressure sensor assembly of claim 9, wherein the signal transmission cable further comprises a strain relief portion between the seal and the sensing element.

11. The pressure sensor assembly of claim 9, wherein the signal transmission cable comprises a fiber optic cable.

12. The pressure sensor assembly of claim 1, wherein the pressure transmission device is disposed within a pressure housing, and wherein the pressure housing is disposed in fluid communication with the first fluid.

13. The pressure sensor assembly of claim 1, wherein the pressure sensing element comprises a glass element.

14. The pressure sensor assembly of claim 1, wherein the pressure sensing element comprises a Bragg grating.

15. The pressure sensor assembly of claim 1, further comprising a bumper element disposed within the housing to limit movement of the sensing element within the housing.

16. The pressure sensor assembly of claim 15, wherein the bumper element is positioned on the sensing element.

17. The pressure sensor assembly of claim 1, wherein the pressure sensor assembly further comprises:

at least one tang positioned on an inside wall of the housing;

at least one bumper element positioned on the sensing element, the bumper element having a groove disposed therein; and

wherein the groove cooperates with the tang to limit the movement of the sensing element within the housing.

18. The pressure sensor assembly of claim 1, wherein the pressure sensor assembly further comprises:

at least one tang positioned on the sensing element;

at least one bumper element positioned on an inside wall of the housing, the bumper element having a groove disposed therein; and

wherein the groove cooperate with the tang to limit the movement of the sensing element within the housing.

19. The pressure sensor assembly of claim 1, wherein the second fluid is void free.

20. A pressure sensor assembly for measuring a pressure of a fluid, comprising:

a housing containing the fluid;

a fiber optic-based pressure sensing element disposed in the fluid within the housing;

a pressure transmission device coupled to the housing and disposed in contact with the fluid, wherein the pressure transmission device transmits the pressure of the fluid to the pressure sensing element and maintains the fluid at a predetermined minimum pressure.

21. The pressure sensor assembly of claim 20, wherein the fluid maintains the sensing element at a near zero base strain condition.

22. The pressure sensor assembly of claim 20, wherein the pressure transmission device comprises an inlet tube having a predetermined inside diameter.

23. The pressure sensor assembly of claim 20, wherein the pressure transmission device comprises a pressure sensitive valve.

24. The pressure sensor assembly of claim 20, further comprising a tube in fluid communication with the fluid.

25. The pressure sensor assembly of claim 20, wherein the pressure sensor assembly further comprises:

a seal disposed in the housing; and

a signal transmission cable coupled to the sensing element and extending through the seal to the outside of the housing.

26. The pressure sensor assembly of claim 25, wherein the signal transmission cable further comprises a strain relief portion between the seal and the sensing element.

27. The pressure sensor assembly of claim 25, wherein the signal transmission cable comprises a fiber optic cable.

28. The pressure sensor assembly of claim 20, wherein the pressure transmission device is disposed within a pressure housing, and wherein the pressure housing is disposed in fluid communication with the fluid.

29. The pressure sensor assembly of claim 20, wherein the pressure transmission device maintains the fluid within the housing substantially void free.

30. The pressure sensor assembly of claim 20, wherein the sensing element floats within the fluid within the housing.

31. The pressure sensor assembly of claim 20, further comprising a bumper element disposed within the housing to limit movement of the sensing element within the housing.

32. The pressure sensor assembly of claim 31, wherein the bumper element is positioned on the sensing element.

33. The pressure sensor assembly of claim 20, wherein the pressure sensor assembly further comprises:

at least one tang positioned on an inside wall of the housing;

at least one bumper element positioned on the sensing element, the bumper element having a groove disposed therein; and

wherein the groove cooperates with the tang to limit the movement of the sensing element within the housing.

34. The pressure sensor assembly of claim 20, wherein the pressure sensor assembly further comprises:

at least one tang positioned on the sensing element;

at least one bumper element positioned on an inside wall of the housing, the bumper element having a groove disposed therein; and

wherein the groove cooperate with the tang to limit the movement of the sensing element within the housing.

35. The pressure sensor assembly of claim 20, wherein the pressure sensing element comprises a Bragg grating.