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EP0140295A2 Expired / Lapsed EP ⏱️ 0.0 years remaining

Method of operating an air-fuel ratio sensor

Assignee: Hitachi Ltd
•
Filing: 1984-10-18
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Granted: —
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Expires: 2004-10-18
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Abstract

Abstract 0 An air-fuel ratio sensor installed in exhaust gas emitted by an internal combustion engine for detecting from the exhaust composition on the air-fuel ratio in the engine becoming equal to a stoichiometric air-fuel ratio. The sensor comprises a solid electrolytic layer of zirconia (10), a pair of electrodes (20, 30) formed on both sides of the electrolytic layer, and a cover (70) provided over the electrolytic layer to enclose one of the electrodes, with a diffusion room formed between the cover and the electrolytic layer and with a gas diffusion hole (5) formed to communicate the diffusion room with the outside of the sensor. The electrode (20) in the diffusion room works as a positive electrode, while another electrode (30) works as a negative electrode to conduct a current (lp) between these electrodes so as to control the oxygen concentration in the diffusion room as a reference oxygen concentration. The fact that the air-fuel ratio has become equal to the stoichiometric air-fuel ratio is detected from a voltage (Eo) appearing between the electrodes.

Inventors

  • 👤 Masayuki Miki
  • 👤 Seikoh Suzuki
  • 👤 Takao Sasayama
  • 👤 Toshitaka Suzuki

Bibliographic Details

Application Number —
Jurisdiction EP
Data Source google_patents
Last Synchronized 2026-11-04 10:00
CPC Classifications
G; G01; G01N; G01N27/00; G01N27/26; G01N27/403; G01N27/406; G01N27/4065; G01N27/407; G01N27/4071; G01N27/4072

Claims Analysis

Total Claims: 7
Claim 1
Independent Claim 169 words
An air-fuel ratio sensor installed in exhaust gas emitted by an internal combustion engine for detecting from the exhaust gas composition that the air-fuel ratio in said engine has become a stoichiometric air-fuel ratio, said sensor comprising: a solid electrolytic layer of zirconia (10); a pair of electrodes (20, 30) formed on both sides of said solid electrolytic layer; and a cover (70) provided on said solid electrolytic layer to enclose one of said electrodes, a diffusion room being formed between said cover and said solid electrolytic layer, and a gas diffusion hole for communicating said diffusion room.with the outside of said sensor, wherein a current (Ip) is conducted between the electrode (20) in said diffusion room as a positive electrode and another electrode (30) as a negative electrode so as to control the oxygen concentration in said diffusion room as a reference oxygen concentration, and fact that the air-fuel ratio has become equal to the stoichiometric air-fuel ratio is detected from a voltage (Eo) generated between said electrodes.
Claim 2
Dependent Claim 169 words
An air-fuel ratio sensor installed in exhaust gas emitted by an internal combustion engine for detecting from the exhaust gas composition that the air-fuel ratio in said engine has become a stoichiometric air-fuel ratio, said sensor comprising: a solid electrolytic layer of zirconia (10); a pair of electrodes (20, 30) formed on both sides of said solid electrolytic layer; and a cover (70) provided on said solid electrolytic layer to enclose one of said electrodes, a diffusion room being formed between said cover and said solid electrolytic layer, and a gas diffusion hole for communicating said diffusion room.with the outside of said sensor, wherein a current (Ip) is conducted between the electrode (20) in said diffusion room as a positive electrode and another electrode (30) as a negative electrode so as to control the oxygen concentration in said diffusion room as a reference oxygen concentration, and fact that the air-fuel ratio has become equal to the stoichiometric air-fuel ratio is detected from a voltage (Eo) generated between said electrodes.
Claim 3
Dependent Claim 26 words
A sensor according to claim 1, wherein the oxygen concentration at said positive electrode in said diffusion room is controlled by the constant current excitation method.
Claim 4
Dependent Claim 24 words
A sensor according to claim 2, wherein said gas diffusion hole has a sectional area 1/100 or less the area of said negative electrode.
Claim 5
Dependent Claim 28 words
A sensor according to claim 3, wherein said gas diffusion hole has a shape of a groove and is located between said cover and said solid electrolytic layer.
Claim 6
Dependent Claim 21 words
A sensor according to claim 4, wherein said gas diffusion hole and said diffusion room are formed using an organic binder.
Claim 7
Dependent Claim 12 words
A sensor according to claim 5, wherein said sensor incorporates a heater.

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