Ultra-high pressure transducer

• US 5,329,819 A
• Filed: 05/06/1993
• Issued: 07/19/1994
• Est. Priority Date: 05/06/1993
• Status: Expired due to Fees

• Current Assignee: Kavlico Corporation (Sensata Technologies Holding Plc)
• Original Assignee: Kavlico Corporation (Sensata Technologies Holding Plc)
• Inventors: Tirmizi, Abrar A., Park, Kyong M.
• Primary Examiner(s): Woodiel, Donald
• Application Number:
  US08/057,541
• Time in Patent Office: 439 Days
• Field of Search: 73/718, 73/724, 73/706, 361/283.1, 361/283.2, 361/283.3, 361/283.4
• US Class Current: 73/724
• CPC Class Codes: G01L 9/0075 using a ceramic diaphragm, e.g. alumina, fused quartz, glass

Abstract

A simple, reliable and inexpensive ultra high pressure transducer includes a basic capacitive transducer, made of two closely spaced insulating plates whose opposed faces contain conductive layers, and one of which plates is a thin and flexible diaphragm of low mechanical hysteresis. In mechanical coupling proximity with this insulating diaphragm is a thick metal diaphragm which is a part of the ultra high pressure coupling component. The flexure of this thick metal diaphragm under ultra high pressures, which are applied only on the side opposite the insulating diaphragm, determines the magnitude of the deflection of both diaphragms, and, corresponding to the resultant output capacitance level, provides a measure of the ultra high pressure level.

Claims

1. A simple and reliable ultra high pressure transducer comprising:

a capacitive pressure transducer made of two closely spaced insulating plates of low mechanical hysteresis material, said plates each having a layer of conductive material on their opposed faces forming electrodes which are spaced slightly apart from one-another, and at least one of said plates being a thin diaphragm which is flexible under applied deflection forces to deflect toward the other plate and change the capacitance between said electrodes, said thin diaphragm being mounted to and spaced apart from the other insulating plate at the facing surfaces of the outer peripheries thereof;

an ultra high pressure fitting including an ultra high pressure input coupling part for connecting to a source of ultra high pressure fluid, and a thick, flat flexible metal diaphragm integral with said fitting and in mechanical coupling proximity with said thin diaphragm over the greater portion of the active areas of said thin and thick diaphragms;

said thick metal diaphragm constituting means for determining the magnitude of the deflection of said thin and thick diaphragms as pressure to said ultra high pressure input coupling part is varied; and

an ultra high pressure chamber adjacent to and having an extent comparable to that of said thick metal diaphragm, said chamber being connected to said input coupling part;

whereby, when the ultra high pressure applied to said input coupling part changes, the corresponding pressure change in said chamber causes the deflection of said thin and thick diaphragms to change correspondingly, and the resultant changed output capacitance of the transducer indicates the new ultra high pressure level.

2. An ultra high pressure transducer as defined in claim 1 wherein said insulating plates are made of alumina.

3. An ultra high pressure transducer as defined in claim 1 wherein said fitting and said thick metal diaphragm are made of steel.

4. An ultra high pressure transducer as defined in claim 1 wherein said thin insulating diaphragm is of the order of 0.005 to 0.070 inch thick.

5. An ultra high pressure transducer as defined in claim 1 wherein said thick metal diaphragm is in the order of 0.020 to 0.500 inch thick.

6. An ultra high pressure transducer as defined in claim 1 wherein said thin diaphragm and said thick metal diaphragm are bonded together by means of a high-temperature, high strength, low mechanical hysteresis epoxy applied to their cleaned mating surfaces with care to exclude trapped air or foreign substances.

7. An ultra high pressure transducer as defined in claim 1 wherein said two insulating plates and said thick metal diaphragm are circular in configuration.

8. An ultra high pressure transducer as defined in claim 1 wherein said insulating plates are formed of high compressive strength material.

9. An ultra high pressure transducer as defined in claim 1 wherein the diameter of said thick metal diaphragm is in the order of 0.25 inch to 2.00 inches.

10. A simple and reliable ultra high pressure transducer comprising:

a capacitive pressure transducer made of two closely spaced insulating plates of low mechanical hysteresis material, said plates each having a layer of conductive material on their opposed faces forming electrodes which are spaced slightly from one-another, and at least one of said plates being a thin diaphragm which is flexible under applied deflection forces to deflect toward the other plate and change the capacitance between said electrodes, said thin diaphragm being mounted to and spaced apart from the other insulating plate at the facing surfaces of the outer peripheries thereof;

an ultra high pressure fitting including an ultra high pressure input coupling part for handling pressures in excess of 20,000 psi and for connecting to a source of ultra high pressure fluid, and a thick, flat flexible metal diaphragm integral with said fitting and bonded to said thin diaphragm over the greater portion of the active areas of said thin and thick diaphragms;

said thick metal diaphragm constituting means for determining the magnitude of the deflection of said bonded thin and thick diaphragms as pressure to said ultra high pressure input coupling part is varied; and

an ultra high pressure chamber adjacent to and having an extent comparable to that of said thick metal diaphragm, said chamber being connected to said input coupling part;

whereby, when the ultra high pressure applied to said input coupling part changes the corresponding pressure change in said chamber causes the deflection of said bonded thick and thin diaphragms to change correspondingly, and the resultant changed output capacitance of the transducer indicates the new ultra high pressure level.

11. An ultra high pressure transducer as defined in claim 10 wherein said insulating plates are made of alumina.

12. An ultra high pressure transducer as defined in claim 10 wherein said fitting and said thick metal diaphragm are made of steel.

13. An ultra high pressure transducer as defined in claim 10 wherein said thin insulating diaphragm is of the order of 0.005 to 0.070 inch thick.

14. An ultra high pressure transducer as defined in claim 10 wherein said thick metal diaphragm is in the order of 0.020 to 0.500 inch thick.

15. An ultra high pressure transducer as defined in claim 10 wherein said insulating diaphragm and said thick metal diaphragm are bonded together by means of a high-temperature, high strength, low mechanical hysteresis epoxy applied to their cleaned mating surfaces with care to exclude trapped air or foreign substances.

16. An ultra high pressure transducer as defined in claim 10 wherein said two insulating plates and said thick metal diaphragm are circular in configuration.

17. An ultra high pressure transducer as defined in claim 10 wherein said insulating plates are formed of high compressive strength material.

18. An ultra high pressure transducer as defined in claim 10 wherein the diameter of said thick metal diaphragm is in the order of 0.25 inch to 2.00 inches.

19. A simple and reliable ultra high pressure transducer comprising:

a capacitive pressure transducer made of two closely spaced insulating plates of low mechanical hysteresis material, said plates each having a layer of conductive material on their opposed faces forming electrodes which are spaced slightly apart from one-another, and at least one of said plates being a thin diaphragm which is flexible under applied deflection forces to deflect toward the other plate and change the capacitance between said electrodes, said thin diaphragm being mounted to and spaced apart from the other insulating plate at the facing surfaces of the outer peripheries thereof;

an ultra high pressure fitting including an ultra high pressure input coupling part for handling pressures in excess of 20,000 psi and for connecting to a source of ultra high pressure fluid, and a thick, flat flexible metal diaphragm joined integrally with said fitting and bonded to said thin diaphragm over the greater portion of the active areas of said thin and thick diaphragms;

said thick metal diaphragm constituting means for determining the magnitude of the deflection of said bonded thin and thick diaphragms as pressure to said ultra high pressure input coupling part is varied; and

an ultra high pressure chamber adjacent to and having an extent comparable to that of said thick metal diaphragm, said chamber being connected to said input coupling part;

whereby, when the ultra high pressure applied to said input coupling part changes, the corresponding pressure change in said chamber causes the deflection of said bonded thin and thick diaphragms to change correspondingly, and the resultant changed output capacitance of the transducer indicates the new ultra high pressure level.

20. An ultra high pressure transducer as defined in claim 19 wherein said integral joining of said metal diaphragm and said fitting is achieved by means of a technique selected from the class consisting of:

(a) friction welding of two flat, contiguous metal surfaces; and

(b) extended threaded engagement combined with brazing of the threaded surfaces using silver solder.