Air fuel ratio sensor
AssigneeNgk Spark Plug Co., Ltd.
InventorsNobuhiro Hayakawa, Tessho Yamada
Life of this patent
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Abstract
The invention provides an air/fuel ratio sensor, including an electrochemical sensor cell and an electrochemical pump cell, which shows both a quick response and a stable limiting current. This is realized by limiting the ratio of the area a of a region A to the area b of a region B on the inner electrode of the electrochemical sensor within a specified range, 0<a/b.ltoreq.0.1. Here, the region A corresponds to a region C within a 0.5 mm distance from the end of the gas diffusion hole except on the 0.5 mm distance line on the inner electrode of the electrochemical pump cell, and the region B corresponds to a region D or the complement of the region C on the inner electrode of the electrochemical pump cell.
Claims19
An air/fuel ratio sensor comprising:
- (a) an electrochemical pump cell having porous inner and outer electrodes on respective sides of a solid electrolyte base;
- (b) an electrochemical sensor cell having porous inner and outer electrodes on respective sides of a solid electrolyte base, said inner electrode of said electrochemical sensor cell facing said inner electrode of said electrochemical pump cell on opposite sides of a gas diffusion chamber;
- and,
- (c) a gas diffusion conduit connecting said gas diffusion chamber to an atmosphere;
- (d) a Vs electrode, wherein the Vs electrode is the inner electrode of the electrochemical sensor cell;
- (e) an area "a" of the Vs electrode has a ratio with respect to an area "b" on said Vs electrode of said electrochemical sensor cell within the range, 0<a/b<0.1;
- (f) wherein "a" is the total area of the Vs electrode which extends a distance of within less then 0.5 mm from an end of the gas diffusion chamber;
- (g) said area "b" is the total area of the Vs electrode minus the area "a".
An air/fuel ratio sensor comprising:
- (a) an electrochemical pump cell having porous inner and outer electrodes on respective sides of a solid electrolyte base;
- (b) an electrochemical sensor cell having porous inner and outer electrodes on respective sides of a solid electrolyte base, said inner electrode of said electrochemical sensor cell facing said inner electrode of said electrochemical pump cell on opposite sides of a gas diffusion chamber;
- and,
- (c) a gas diffusion conduit connecting said gas diffusion chamber to an atmosphere;
- wherein,
- (d) said gas diffusion chamber is elongated having a length longer than a width thereof;
- (e) said conduit communicates with said gas diffusion chamber at a center portion thereof;
- and,
- (f) said inner electrode of said electrochemical sensor is elongated having a length longer than a width thereof, said inner electrode of said electrochemical sensor being positioned within said gas diffusion chamber with length axes thereof in alignment
- (g) a Vs electrode, wherein the Vs electrode is the inner electrode of the electrochemical sensor cell, and further wherein said air/fuel ratio sensor has the characteristics of:
- (h) an area "a" of the Vs electrode has a ratio with respect to an area "b" on said Vs electrode of said electrochemical sensor cell within the range, 0<a/b<0.1;
- (i) wherein "a" is the total area of the Vs electrode which extends a distance of within less than 0.5 mm from the end of the gas diffusion chamber;;
- (j) said area "b" is the total area of the Vs electrode minus the area "a".
Dependencies are inferred from the claim text.