Patent US4198670A successfully refreshed from Google Patents.
US4198670A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Capacitive pressure transducer
Assignee: Motors Liquidation Co
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Filing: 1978-11-20
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Granted: 1980-04-15
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Expires: 1998-11-20
Abstract
Abstract A variable capacitor includes a metal diaphragm arranged to flex in response to an applied pressure differential serving as a movable capacitor plate and a fixed capacitor plate closely spaced from the diaphragm. At least one of the two capacitor plates has an insulating layer of metal oxide formed thereon to prevent electrical contact therebetween. By making the capacitor plate of an iron-chrome-aluminum alloy and heating the capacitor plate, an aluminum oxide layer is formed thereon. The fixed capacitor plate is formed in a hat-shaped configuration with the brim portion spaced far from the diaphragm by an insulating spacer to minimize the fixed capacitance around the edge of the capacitor assembly.
Inventors
- 👤 Gamdur S. Mann
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 03:08
CPC Classifications
G; G01; G01L; G01L9/00; G01L9/0041; G01L9/0072
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
170 words
A capacitive pressure transducer comprising a pressure responsive movable capacitor plate assembly including a metal diaphragm attached to support means at its periphery, a fixed hat-shaped capacitor plate having a central surface closely spaced from the diaphragm to form with said diaphragm a capacitor of substantial value which is variable according to the position of the diaphragm and further having a peripheral surface widely spaced from the said support means to form a capacitor of fixed capacitance which is small relative to the said variable capacitance, an insulating layer of metal oxide formed on at least one of the diaphragms and the fixed capacitor plate for preventing electrical contact therebetween, an insulating spacer between the peripheral surface of the fixed capacitor plate and the said assembly, conductive leads connected to the fixed capacitor plate and the movable capacitor plate assembly, and means for applying a pressure differential across the diaphragm whereby when pressure is applied the diaphragm flexes to vary the capacitance according to the value of the pressure differential.
Claim 2
Dependent Claim
170 words
A capacitive pressure transducer comprising a pressure responsive movable capacitor plate assembly including a metal diaphragm attached to support means at its periphery, a fixed hat-shaped capacitor plate having a central surface closely spaced from the diaphragm to form with said diaphragm a capacitor of substantial value which is variable according to the position of the diaphragm and further having a peripheral surface widely spaced from the said support means to form a capacitor of fixed capacitance which is small relative to the said variable capacitance, an insulating layer of metal oxide formed on at least one of the diaphragms and the fixed capacitor plate for preventing electrical contact therebetween, an insulating spacer between the peripheral surface of the fixed capacitor plate and the said assembly, conductive leads connected to the fixed capacitor plate and the movable capacitor plate assembly, and means for applying a pressure differential across the diaphragm whereby when pressure is applied the diaphragm flexes to vary the capacitance according to the value of the pressure differential.
Claim 3
Dependent Claim
181 words
A capacitive pressure transducer comprising a pressure responsive movable capacitor plate assembly including a metal diaphragm welded to metal support means at its periphery, the diaphragm comprising an iron-chromium-aluminum alloy with its surface oxidized to form thereon an insulating coating of aluminum oxide, a fixed hat-shaped capacitor plate having a central surface closely spaced from the diaphragm to form with said diaphragm a capacitor of substantial value which is variable according to the position of the diaphragm and protected from electrical contact therewith by the said insulating oxide coating, the fixed capacitor plate further having a peripheral surface widely spaced from the said support means to form a capacitor of fixed capacitance which is small relative to the said variable capacitance, an insulating spacer between the peripheral surface of the fixed capacitor plate and the said assembly, conductive leads connected to the fixed capacitor plate and the movable capacitor plate assembly, and means for applying a pressure differential across the diaphragm whereby when pressure is applied the diaphragm flexes to vary the capacitance according to the value of the pressure differential.
Claim 4
Dependent Claim
181 words
A capacitive pressure transducer comprising a pressure responsive movable capacitor plate assembly including a metal diaphragm welded to metal support means at its periphery, the diaphragm comprising an iron-chromium-aluminum alloy with its surface oxidized to form thereon an insulating coating of aluminum oxide, a fixed hat-shaped capacitor plate having a central surface closely spaced from the diaphragm to form with said diaphragm a capacitor of substantial value which is variable according to the position of the diaphragm and protected from electrical contact therewith by the said insulating oxide coating, the fixed capacitor plate further having a peripheral surface widely spaced from the said support means to form a capacitor of fixed capacitance which is small relative to the said variable capacitance, an insulating spacer between the peripheral surface of the fixed capacitor plate and the said assembly, conductive leads connected to the fixed capacitor plate and the movable capacitor plate assembly, and means for applying a pressure differential across the diaphragm whereby when pressure is applied the diaphragm flexes to vary the capacitance according to the value of the pressure differential.
Claim 5
Dependent Claim
219 words
A capacitive pressure transducer comprising cup-shaped support means having an annular rim about its opening a pressure responsive movable capacitor plate assembly including the said support means and a metal diaphragm attached and sealed to the annular rim of the support means to define a closed chamber, a gas within the closed chamber at a preset reference pressure, the diaphragm having an insulating layer of metal oxide formed on the surface thereof, a fixed hat-shaped capacitor plate mounted outside the closed chamber and having a central surface closely spaced from the diaphragm to form with said diaphragm a capacitor of substantial value which is variable according to the position of the diaphragm and protected from electrical contact therewith by the said insulating oxide layer, the fixed capacitor plate further having a peripheral surface widely spaced from the said support means to form a capacitor of fixed capacitance which is small relative to the said variable capacitance, an insulating spacer between the peripheral surface of the fixed capacitor plate and the said assembly, conductive leads connected to the fixed capacitor plate and the movable capacitor plate assembly, and means for applying a pressure on the diaphragm outside the closed chamber whereby when pressure is applied the diaphragm flexes to vary the capacitance according to the value of the applied pressure.
Claim 6
Dependent Claim
219 words
A capacitive pressure transducer comprising cup-shaped support means having an annular rim about its opening a pressure responsive movable capacitor plate assembly including the said support means and a metal diaphragm attached and sealed to the annular rim of the support means to define a closed chamber, a gas within the closed chamber at a preset reference pressure, the diaphragm having an insulating layer of metal oxide formed on the surface thereof, a fixed hat-shaped capacitor plate mounted outside the closed chamber and having a central surface closely spaced from the diaphragm to form with said diaphragm a capacitor of substantial value which is variable according to the position of the diaphragm and protected from electrical contact therewith by the said insulating oxide layer, the fixed capacitor plate further having a peripheral surface widely spaced from the said support means to form a capacitor of fixed capacitance which is small relative to the said variable capacitance, an insulating spacer between the peripheral surface of the fixed capacitor plate and the said assembly, conductive leads connected to the fixed capacitor plate and the movable capacitor plate assembly, and means for applying a pressure on the diaphragm outside the closed chamber whereby when pressure is applied the diaphragm flexes to vary the capacitance according to the value of the applied pressure.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1983-04-15 | 1983-10-15 | 1984-04-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1987-04-15 | 1987-10-15 | 1988-04-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1991-04-15 | 1991-10-15 | 1992-04-15 | $7700.00 | Window Closed / Lapsed |