PRESSURE MEASUREMENT TRANSDUCER WITH PROTECTIVE DEVICE

• US 20080168846A1
• Filed: 01/16/2007
• Published: 07/17/2008
• Est. Priority Date: 01/16/2007
• Status: Active Grant

• Current Assignee: Raytheon Company (Rtx Corporation)
• Original Assignee: Raytheon Company (Rtx Corporation)
• Inventors: Lukens, Peter C.
• Granted Patent: US 7,434,471 B2
• Time in Patent Office: Days
• US Class Current: 73/862.581
• CPC Class Codes: G01L 19/06 Means for preventing overload or deleterious influence of the measured medium on the measuring device or vice versa

Abstract

A pressure measurement device with protection from long-term loads and pressure shocks. The novel device includes a diaphragm adapted to deform in response to a pressure applied thereto, and a retractable support adapted to support the diaphragm during periods of non-operation. A strain gauge is attached to the diaphragm for measuring the deformation and the retractable support is designed to minimize stress on the strain gauge during periods of non-operation. The support is retracted during periods of operation to allow the diaphragm and strain gauge to function normally in response to the applied pressure. The diaphragm is disposed within a housing to form a first cavity, which is coupled to media to be measured, and a second cavity, which is set at a reference pressure. In an illustrative embodiment, the retractable support is a threaded plug inserted into the second cavity.

Claims

1. A device for measuring pressure comprising:

a diaphragm adapted to deform in response to a pressure applied thereto during periods of operation and

first means for minimizing deformation in said diaphragm during periods of non-operation.

2. The invention of claim 1 wherein said first means includes a retractable support adapted to support said diaphragm such that deformation is minimized during periods of non-operation and to retract to allow deformation in said diaphragm during periods of operation.

3. The invention of claim 2 wherein said device further includes second means for measuring said deformation in said diaphragm.

4. The invention of claim 3 wherein said second means includes a strain gauge attached to said diaphragm such that a deformation of said diaphragm introduces a strain in said gauge.

5. The invention of claim 4 wherein said first means is adapted to support said diaphragm such that strain on said strain gauge is minimized.

6. The invention of claim 5 wherein said device further includes a housing.

7. The invention of claim 6 wherein said diaphragm is disposed within said housing such that an interior of said housing is separated into first and second cavities.

8. The invention of claim 7 wherein said first cavity is coupled to media to be measured.

9. The invention of claim 8 wherein said second cavity is set to a reference pressure.

10. The invention of claim 9 wherein said first means includes a retractable support inserted into said second cavity.

11. The invention of claim 10 wherein said first means further includes means for moving said retractable support to support said diaphragm during periods of non-operation and retracting said support from said diaphragm during periods of operation.

12. The invention of claim 11 wherein said first means further includes third means for determining a placement of said support.

13. The invention of claim 12 wherein said third means is adapted to determine the placement of said support depending on an output signal from said strain gauge.

14. The invention of claim 13 wherein said support is inserted into said second cavity until there is a null is said output signal.

15. The invention of claim 10 wherein said device further includes means for fluid to flow in and out of said second cavity to maintain neutral pressure when said support is inserted or retracted.

16. A pressure transducer comprising:

a housing;

a diaphragm disposed within said housing to form a first cavity and a second cavity, said diaphragm adapted to deform in response to a pressure difference between said first and second cavities;

a strain gauge attached to said diaphragm such that a deformation of said diaphragm introduces a strain in said gauge, said strain gauge generating an electrical output signal in response to said strain; and

a retractable support disposed within said second cavity and adapted to support said strain gauge during periods of non-operation and retract from said strain gauge during periods of operation.

17. The invention of claim 16 wherein said retractable support is adapted to support said strain gauge such that strain on said strain gauge is minimized.

18. The invention of claim 16 wherein said first cavity is coupled to media to be measured.

19. The invention of claim 18 wherein said second cavity is set to a reference pressure.

20. The invention of claim 16 wherein said strain gauge is a solid-state strain gauge.

21. The invention of claim 16 wherein said retractable support is a threaded plug.

22. The invention of claim 21 wherein said housing includes a mating thread for said threaded plug in said second cavity.

23. The invention of claim 16 wherein said retractable support includes a gas relief channel for maintaining neutral gas pressure when said support is inserted in or retracted from said second cavity.

24. The invention of claim 16 wherein said housing includes a wiring channel for making electrical connections with said strain gauge.

25. The invention of claim 16 wherein said pressure transducer further includes a mechanism for moving said retractable support in response to a control signal.

26. The invention of claim 25 wherein said pressure transducer further includes a control system for generating said control signal.

27. The invention of claim 26 wherein said control system is adapted to generate a control signal instructing said mechanism to move said support away from said strain gauge by some predetermined amount when said transducer is to begin acquiring measurements.

28. The invention of claim 27 wherein said control system is adapted to generate a control signal instructing said mechanism to move said support towards said strain gauge by some predetermined amount when said transducer is finished acquiring measurements.

29. The invention of claim 26 wherein said control system is adapted to receive said output signal and in accordance therewith generate said control signal.

30. The invention of claim 29 wherein said control signal is adapted to instruct said mechanism to move said support towards said strain gauge until there is a null is said output signal.

31. The invention of claim 16 wherein said housing and/or retractable support include Vernier scale markings to indicate a location to which said support should be inserted.

32. The invention of claim 16 wherein said housing and/or retractable support include Vernier scale markings to indicate a location to which said support should be retracted.

33. A method for protecting a pressure transducer from long term loads and pressure shocks including the steps of:

applying a pressure to be measured to said transducer such that a diaphragm in said transducer deforms in response to said pressure;

providing a strain gauge attached to said diaphragm to measure a deformation in said diaphragm;

supporting said diaphragm and strain gauge using a retractable support to minimize stress on said strain gauge during periods of non-operation; and

retracting said support to allow said diaphragm to deform and said strain gauge to obtain deformation measurements during periods of operation.