Compensated pressure transducer

• US 3,962,921 A
• Filed: 09/07/1973
• Issued: 06/15/1976
• Est. Priority Date: 02/04/1972
• Status: Expired due to Term

• Current Assignee: The Garrett Corporation
• Original Assignee: The Garrett Corporation
• Inventors: Lips, Donald C.
• Primary Examiner(s): Woodiel, Donald O.
• Application Number:
  US05/395,320
• Time in Patent Office: 1,012 Days
• Field of Search: 73/398 R, 73/388, 73/398 C, 73/393, 73/407 R, 317/246
• US Class Current: 73/724
• CPC Class Codes: G01L 19/02 Arrangements for preventing, or for compensating for, effects of inclination or acceleration of the measuring device; Zero-setting means for aneroid barometers G01L7/14
• CPC Class Codes: G01L 9/0072 using variations in capacitance
• CPC Class Codes: G01L 9/0075 using a ceramic diaphragm, e.g. alumina, fused quartz, glass

Abstract

A pair of diaphragms with substantially equal natural frequencies are superposed for movement in phase and in unison under accelerating forces, with electrical capacitor plates deposited on adjacent surfaces which provide an electrical measure of the differential diaphragm stressing with one of the diaphragms subject to a fluid pressure differential.

Claims

1. A transducer comprising first and second stress force sensing deflection diaphragms mounted in face-to-face relationship for deflection thereof by application thereto of first and second stress forces, the diaphragms having edges in sealing engagement, one of the diaphragms having a recessed deflection surface;

means for maintaining zero pressure differential across one of said diaphragms; and

signal means electrically coupled with said diaphragms for providing an electrical output related to the deflection of one of said diaphragms to said second stress force, electrical output related to the deflection of said one of said diaphragms to said first stress force being substantially prevented by the deflection of the other of said diaphragms to said first stress force.

2. The transducer of claim 1 wherein said recessed deflection surface of said diaphragm comprises a concave surface.

3. A transducer comprising first and second stress force sensing deflection diaphragms disposed in face-to-face relationship;

means mounting said diaphragms for deflection thereof by application thereto of first and second stress forces;

means for maintaining zero pressure differential across one of said diaphragms, and signal means comprising first and second capacitor electrode elements disposed on said diaphragms in face-to-face relationship, a dielectric medium disposed between said capacitor electrode elements, and an inductance coil coupled with said capacitor electrode elements to form a tank circuit for providing an electrical output related to the deflection of one of said diaphragms to said second stress force, electrical outputs related to the deflection of said one of said diaphragms to said first stress force being substantially prevented by the deflection of the other of said diaphragms to said first stress force.

4. The transducer of claim 3 wherein said diaphragms are disposed outside of said inductance coil.

5. A transducer comprising first and second stress force sensing deflection diaphragms disposed in face-to-face relationship;

means mounting said diaphragms for deflection thereof by application thereto of first and second stress forces;

means for maintaining zero pressure differential across one of said diaphragms; and

signal means comprising first and second capacitor electrode elements disposed on said diaphragms in face-to-face relationship and a third capacitor element disposed on one of said diaphragms in side-by-side relationship to one of said capacitor elements and in face-to-face relationship to said other capacitor element, each of the capacitor electrode elements being movable with its respective diaphragm, and a dielectric medium disposed between said capacitor electrode elements for providing an electrical output related to the deflection of one of said diaphragms to said second stress force, electrical output related to the deflection of said one of said diaphragms to said first stress force being substantially prevented by the deflection of the other of said diaphragms to said first stress force.

6. The transducer of claim 5 in which said dielectric medium between said capacitor electrode elements has a dielectric constant of as great as one.

7. The transducer of claim 5 further comprising an inductance coil, said inductance coil being coupled with said capacitor electrode elements to form a tank circuit.

8. The transducer of claim 7 in which said first and third capacitor electrode elements are electrically wired to said inductance coil.

9. The transducer of claim 7 in which said diaphragms are disposed outside of said coil.

10. A transducer comprising first and second stress force sensing deflection diaphragms disposed in face-to-face relationship;

means mounting said diaphragms for deflection thereof by application thereto of first and second stress forces;

means for maintaining zero pressure differential across one of said diaphragms; and

signal means comprising first and second capacitor electrode elements disposed on said diaphragms in face-to-face relationship, each of the capacitor electrode elements being movable with its respective diaphragm, a dielectric medium disposed between said capacitor electrode elements, an inductance coil, a cup-like transducer housing disposed about said coil and joined therewith, said housing being further joined to said means mounting said diaphragms, and means for electrically coupling said coil to said capacitor electrode elements to form a tank circuit for providing an electrical output related to the deflection of one of said diaphragms to said second stress force, electrical output related to the deflection of said one of said diaphragms to said first stress force being substantially prevented by the deflection of the other of said diaphragms to said first stress force.

11. The transducer of claim 10 in which the inside wall of said housing is grooved for receiving said coil body.

12. The transducer of claim 11 in which said coil is bonded to the wall of said groove.

13. The transducer of claim 10 in which said dielectric medium between said capacitor electrode elements has a dielectric constant of as great as one.