Patent EP0517366A1 successfully refreshed from Google Patents.
EP0517366A1
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EP
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Method and apparatus for sensing oxides of Nitrogen
Assignee: Ford-Werke GmbH
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Filing: 1992-04-30
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Granted: —
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Expires: 2012-04-30
Abstract
Abstract The present invention relates to a structure and a method for sensing oxides of nitrogen in a gas, for example, the exhaust gas of an internal combustion engine. The measurement gas along with oxygen provided by a solid state electrochemical oxygen pumping cell (10) is passed through an oxidation catalyst (17) to oxidise and remove any reducing species in the gas, e.g., carbon monoxide, hydrocarbons, and hydrogen. The oxides of nitrogen are then sensed by a gas sensor (19) which otherwise would respond to both oxides of nitrogen and reducing species in the gas.
Inventors
- 👤 Eleftherios M. Logothetis
- 👤 Richard E. Soltis
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-04 12:31
CPC Classifications
G; G01; G01N; G01N27/00; G01N27/26; G01N27/416; G01N27/417; G01N27/419; G01N27/403; G01N27/406; G01N27/407; G01N27/4073; G01N27/4074
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
142 words
A method of sensing oxides of nitrogen in a measurement gas also containing reducing gases including the steps of: positioning an oxidisation catalyst (17) dispersed in a supporting matrix between said measurement gas and an oxides of nitrogen semiconductor sensor (19); isolating said oxides of nitrogen semiconductor sensor (19) from the measurement gas; providing oxygen for diffusion into the matrix comprising the oxidation catalyst (17) by means of a solid state electrochemical oxygen pumping cell (10), exposing the oxidation catalyst (17) to the measurement gas and the oxygen; passing the measurement gas through the oxidisation catalyst (17) which oxidises the reducing gases without affecting any NO₂ present; and passing the gaseous output from the oxidation catalyst (17) to the oxides of nitrogen semiconductor sensor (19) to detect the amount of oxides of nitrogen by sensing the change in resistance of the sensor.
Claim 2
Dependent Claim
23 words
A method according to claim 1, further comprising the step of heating the oxidisation catalyst to a temperature in excess of about 200/C.
Claim 3
Dependent Claim
35 words
A method according to claim 2 wherein the measurement gas is the exhaust gas of an internal combustion engine and oxygen is generated by the dissociation of carbon dioxide and water in the exhaust gas.
Claim 4
Dependent Claim
29 words
A method according to claim 1 further comprising the step of providing an ambient air atmosphere in contact with an electrode of the solid state electrochemical oxygen pumping cell.
Claim 5
Independent Claim
167 words
An apparatus for sensing oxides of nitrogen in a measurement gas also containing reducing gases comprising: a solid state electrochemical oxygen pumping cell (10) capable of providing oxygen comprising an electrode layer (12,13) on each of two opposite side of an oxygen-ion conducting solid electrolyte member (11); an oxidation catalyst means (17), dispersed in a porous matrix and located adjacent the solid state electrochemical oxygen pumping cell (10), for accepting and passing the measurement gas and the oxygen and oxidising any reducing species present in the measurement gas without affecting any NO₂ present; a semiconductor sensor means (19) located adjacent the oxidation catalyst means (17) and shielded from the measurement gas so as to be exposed to an oxidised gas passed by the oxidation catalyst means (17) and generating an output signal responsive to oxides of nitrogen in the oxidised gas so that the sensor means is substantially isolated from the reducing species in the measurement gas and the output is a function of oxides of nitrogen.
Claim 6
Dependent Claim
26 words
An apparatus according to claim 5, wherein the matrix is an inert ceramic with metal oxidation catalyst particles deposited on walls of pores of the ceramic.
Claim 7
Dependent Claim
22 words
An apparatus according to claim 6, wherein the metal oxidation catalyst particles are selected from the group consisting of palladium and platinum.
Claim 8
Dependent Claim
17 words
An apparatus according to claim 5, wherein the semiconductor sensor means is fabricated from SnO₂ and ZnO.
Claim 9
Dependent Claim
11 words
An apparatus according to claim 5, wherein the electrolyte is ZrO₂.
Claim 10
Dependent Claim
31 words
An apparatus according to claim 5, wherein the solid state electrochemical oxygen pumping cell, the oxidation catalyst means and the sensor means are formed as one integrated structure, in that order.
References Cited (Backward Citations)
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