Patent US4347495A successfully refreshed from Google Patents.
US4347495A
Expired / Lapsed
US
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Method of detecting oxygen and an oxygen sensor therefor
Assignee: Emerson Process Management Ltd
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Filing: 1980-01-31
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Granted: 1982-08-31
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Expires: 2000-01-31
Abstract
Abstract An oxygen sensing element has a body of chromium-rich zinc chromite and electrodes in contact with it for sensing the electrical resistance. At elevated temperatures, the resistance varies with oxygen concentration. A rare earth oxide dopant, preferably 15% mole percent Lanthanum 10 oxide, stabilizes and improves performance.
Inventors
- 👤 Donald N. Hunter
- 👤 Richard J. Brook
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 14:17
CPC Classifications
G; G01; G01N; G01N27/00; G01N27/02; G01N27/04; G01N27/12
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
43 words
A sensing element for an oxygen detector, comprising a body of chromium-rich zinc chromite having in excess of a stoichiometric proportion of chromium in zinc chromite, and means for making electrical contact with the body of zinc chromite to sense its electrical resistance.
Claim 2
Dependent Claim
43 words
A sensing element for an oxygen detector, comprising a body of chromium-rich zinc chromite having in excess of a stoichiometric proportion of chromium in zinc chromite, and means for making electrical contact with the body of zinc chromite to sense its electrical resistance.
Claim 3
Dependent Claim
25 words
An element as claimed in claim 1, wherein chromium is present in approximately 0.2% molar excess of the stoichiometric proportion needed to produce zinc chromite.
Claim 4
Dependent Claim
46 words
An element as claimed in claim 1 or claim 2, wherein the chromium-rich zinc chromite contains up to 25 mole percent of a rare earth oxide dopant (calculated as MO based on the total weight of the doped material, wherein M is the rare earth metal).
Claim 5
Dependent Claim
25 words
An element as claimed in claim 3 wherein the chromium-rich zinc chromite contains between 5 and 20 mole percent of a rare earth oxide dopant.
Claim 6
Dependent Claim
23 words
An element as claimed in claim 4 wherein the chromium-rich zinc chromite contains about 15 mole percent of a rare earth oxide dopant.
Claim 7
Dependent Claim
18 words
An element as claimed in claim 3 wherein the rare earth oxide of the dopant is lanthanum oxide.
Claim 8
Dependent Claim
39 words
An element as claimed in claim 1 wherein the means for making electrical contact includes a pair of electrical conductors provided on the surface of an electrical insulator, the conductors being bridged by said body of chromium-rich zinc chromite.
Claim 9
Dependent Claim
13 words
An element as claimed in claim 7 wherein the conductors are interdigitated combs.
Claim 10
Dependent Claim
80 words
An element as claimed in claim 7 or claim 8 and comprising a substrate of insulating material, a pair of spaced electrodes on a surface of the substrate, a layer of the chromium-rich zinc chromite over said surface with the electrodes, means for heating the substrate and layer to an elevated temperature at which the chromium-rich zinc chromite is responsive to oxygen concentration, and means for connecting the electrodes to a measuring circuit for measuring the resistance between the electrodes.
Claim 11
Independent Claim
64 words
A method of detecting oxygen concentration comprising providing a body of chromium rich zinc chromite having in excess of a stoichiometric proportion of chromium in zinc chromite, heating the body to a temperature at which the resistance of the material of the body is responsive to variations in oxygen concentration in the ambient atmosphere of the body, and measuring the resistance of the material.
Claim 12
Independent Claim
64 words
A method of detecting oxygen concentration comprising providing a body of chromium rich zinc chromite having in excess of a stoichiometric proportion of chromium in zinc chromite, heating the body to a temperature at which the resistance of the material of the body is responsive to variations in oxygen concentration in the ambient atmosphere of the body, and measuring the resistance of the material.
Claim 13
Dependent Claim
32 words
A method as claimed in claim 10 wherein a rare earth oxide dopant is introduced by including a rare earth oxide among the reactants for the preparation of the chromium-rich zinc chromite.
Claim 14
Dependent Claim
26 words
Chromium-rich zinc chromite having in excess of a stoichiometric proportion of chromium in zinc chromite including up to 25 mole percent of a rare earth oxide.
Claim 15
Dependent Claim
26 words
Chromium-rich zinc chromite having in excess of a stoichiometric proportion of chromium in zinc chromite including up to 25 mole percent of a rare earth oxide.
References Cited (Backward Citations)
US3695848A
Cited
US4007435A
Cited
US3932246A
Cited
US4045764A
Cited
FR2331015B1
Cited
US4086556A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1985-08-30 | 1986-03-01 | 1986-08-31 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1989-08-30 | 1990-03-01 | 1990-08-31 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1993-08-30 | 1994-03-01 | 1994-08-31 | $7700.00 | Window Closed / Lapsed |