Pressure sensor system

• US 4,875,369 A
• Filed: 09/08/1987
• Issued: 10/24/1989
• Est. Priority Date: 09/08/1987
• Status: Expired due to Fees

• Current Assignee: Panex Corporation Sugar Land Texas
• Original Assignee: Panex Corporation
• Inventors: Delatorre, Leroy C.
• Primary Examiner(s): LaRoche, Eugene R.
• Assistant Examiner(s): NOT, DEFINED
• Application Number:
  US07/102,020
• Time in Patent Office: 777 Days
• Field of Search: 73/718, 73/724, 73/708, 73/151, 73/862.62, 73/862.63, 361/283
• US Class Current: 73/152.52
• CPC Class Codes: E21B 47/017 Protecting measuring instruments
• CPC Class Codes: E21B 47/06 Measuring temperature or pressure
• CPC Class Codes: G01L 9/0075 using a ceramic diaphragm, e.g. alumina, fused quartz, glass

Abstract

A measurement transducer with a functionally integral quartz material construction to provide spacing measurement gaps transverse to one another with metallized film surfaces defining capacitance plates and electrically conductive paths. The transducer is mounted under compression independent of a protective case and compensates for temperature changes to provide accurate measurements.

Claims

1. A transducer for measuring the displacement of an elastic support member under compression as a function of an applied compressive force comprising:

a support member constructed of a material which responds to forces to be measured with repeatable elastic characteristics and which responds to changes in temperature within a range of operating temperatures with retraceable characteristics and which has a low temperature coefficient of expansion;

said support member having a first set of first facing surfaces defining a first spacing gap where said first facing surfaces are displacable relative to one another as a function of compression of said support member;

first capacitor plate means on said first facing surfaces for deriving a first capacitance measurement as a function of displacement of said first facing surfaces;

said support member having a second set of second facing surfaces defining a second spacing gap located transversely relative to said first spacing gap in said support member; and

second capacitor plate means on said second facing surfaces for deriving a second capacitance measurement as a function of displacement of said second facing surfaces where said first and second capacitance measurements are interrelated functions of the temperature of said support member and where said first and second capacitance measurements are interrelated functions of the displacement of said first facing surfaces and said second facing surfaces.

2. The transducer as defined in claim 1 wherein said member is constructed of quartz material.

3. The transducer as set forth in claim 1 wherein said second set of second facing surfaces are annular and extend over a vertical length "l" and where the outer surface of said support member over said vertical length "l" is cylindrical so that the length "l" is the active measurement length which changes in response to temperature and compression.

4. The transducer as set forth in claim 3 where the active measurement length "l" is equal to the radius of the outer annular second facing surface from a central diameter location.

5. A transducer for measuring the displacement of an elastic material under the compression as a function of applied compressive force comprising:

a cylindrically shaped integral support member constructed of a material which responds to forces to be measured with repeatable elastic characteristics and which responds to changes in temperatures within a range of operating temperatures with retraceable characteristics and which has a low temperature coefficient of expansion;

said support member having upper and lower annular ring portions and a cylindrically shaped central portion;

said central portion having cylindrically shaped upper and lower facing surfaces in parallel planes for defining a first spacing gap, said parallel planes being transverse to the central axis for said support member;

said central portion having an annular space defining inner and outer cylindrically shaped and facing wall surfaces for defining a second spacing gap with a vertical length "l"; and

capacitor plate means on said cylindrical wall surfaces and on said upper and lower facing surfaces for providing at least two electrical capacitors respectively in transverse planes where displacement of said first and second spacing gaps is a function of compression force applied to said ring portions and where the spacing of said first and second spacing gaps is a function of temperature over the vertical length "l".

6. The transducer as defined in claim 5 wherein said member is constructed of quartz material.

7. The transducer as defined in claim 6 wherein a transverse plane to the central axis of said support member bisects the spacing gap between said upper and lower facing surfaces, and said member has a mirror image construction with respect to said transverse plane.

8. The transducer as defined in claim 7 wherein said support member has a uniform construction about the central axis of said member.

9. The transducer as defined in claim 5 wherein said capacitor plate means include thin metalized films.

10. The transducer as defined in claim 5 where the length "l" is equal to the radius for said outer wall surface.

11. A transducer for measuring a compressive force while compensating for temperature effects comprising:

a cylindrically shaped support member constructed with upper and lower components integrally joined together at a transverse plane to a central axis of said support member, said upper and lower components having central facing surfaces and defining a first spacing gap between said facing surfaces;

each of said components being constructed of a ring member part, a toroid member part and a flanged member part where said toroid member part is integrally joined with a flange portion of said flanged member part and said ring member part is integrally joined with said flange member part for defining an annular spacing gap between annular facing surfaces on said toroid part member and said ring part member where said annular spacing gap has an active measurement length "l"; and

capacitor plate means on each of said facing surfaces for providing at least two electrical capacitors.

12. The transducer as defined in claim 11 wherein said support member is constructed of a material which responds to forces to be measured with repeatable elastic characteristics, and which responds to temperature within a range of operating temperatures with retraceable characteristics and which has a low temperature coefficient of expansion.

13. The transducer as defined in claim 12 wherein said member is constructed of quartz material.

14. The transducer as defined in claim 12 wherein

said support member is constructed of quartz material;

said capacitor plate means include thin metalized films;

said toroid member part and said flange member part have access openings for electrical conductor means; and

electrical conductor means connected to said thin metalized films for connection of said capacitor plate means to electrical circuitry.

15. The transducer as defined in claim 14 and further including a layer of metalized film on the end surface of a flange part member.

16. The transducer as defined in claim 14 wherein said electrical conductor means include metalized films.

17. The transducer as defined in claim 14 wherein the flanged member part has an annular depending ring portion which has an internally located lower curved surface joining the inner cylindrical wall of the depending ring portion and which has an annular semi-circular groove located in the surface of the flange portion in a position in vertical alignment with said lower curved surface.

18. The transducer as defined in claim 12 wherein said toroid member part has an annular outer groove.

19. The transducer as defined in claim 12 wherein the length "l" is equal to the radius of the outermost annular surface.