Gas sensor element and gas sensor

Patent metadata

Field	Value
Publication number	US-9696274-B2
Application number	US-201514613251-A
Country	US
Kind code	B2
Filing date	Feb 3, 2015
Priority date	Feb 6, 2014
Publication date	Jul 4, 2017
Grant date	Jul 4, 2017

Abstract

A gas sensor element of an air/fuel ratio sensor has a structure in which at least a part of an end portion of a porous electrode is sandwiched between a porous member and a solid electrolyte member. Therefore, it is possible to restrain shrinkage of the porous electrode during manufacture of the gas sensor element, which shrinkage would otherwise occur at the time of heating in a debindering step or at the beginning of a firing step, whereby occurrence of green breakage in the solid electrolyte member is restrained. Thus, cracking due to green breakage is restrained from occurring in the solid electrolyte member produced through firing. Since the end portion of the porous electrode can receive oxygen through the porous member, blackening of the solid electrolyte member can be prevented.

First claim

What is claimed is:

1. A gas sensor element comprising:
a plate-shaped ceramic solid electrolyte member having a pair of electrodes formed primarily of a metal and disposed on the solid electrolyte member; and
a ceramic dense member layered on the solid electrolyte member and forming at least a portion of a wall surface of a hollow cavity into which gas to be measured or the atmosphere is introduced,
the gas sensor element being adapted to detect a particular gas contained in the gas to be measured, wherein
one of the pair of electrodes is a cavity side electrode disposed to face the hollow cavity;
the cavity side electrode is spaced from the wall surface of the hollow cavity; and
at least one ceramic porous member is provided in the hollow cavity, the ceramic porous member partially covering the cavity side electrode such that the cavity side electrode is partially exposed to the hollow cavity and extending from a position on the cavity side electrode, beyond an end or peripheral edge portion of the cavity side electrode, to a position on a surface of the solid electrolyte member exposed to the hollow cavity.

2. A gas sensor element according to claim 1 , wherein the ceramic porous member for partially covering the cavity side electrode comprises two sections which are provided at each of two positions corresponding to opposite ends of the cavity side electrode in a longitudinal direction thereof, and the opposite ends of the cavity side electrode are sandwiched between the sections of the ceramic porous member and the solid electrolyte member.

3. A gas sensor element according to claim 1 , wherein the ceramic porous member for partially covering the cavity side electrode is formed by at least two separate ceramic porous members which are provided at each of two positions corresponding to opposite ends of the cavity side electrode in a longitudinal direction thereof, and the opposite ends of the cavity side electrode are sandwiched between the ceramic porous member and the solid electrolyte member.

4. A gas sensor element according to claim 1 , further comprising a porous diffusion resistance portion provided in a gas introduction passage extending from an outer wall surface of the gas sensor element to the hollow cavity, wherein the ceramic porous member has a diffusion resistance equal to or smaller than that of the porous diffusion resistance portion.

5. A gas sensor element according to claim 4 , wherein the cavity side electrode is a porous electrode, and has a diffusion resistance equal to or larger than that of the porous diffusion resistance portion.

6. A gas sensor element according to claim 1 , wherein the hollow cavity is a measuring chamber into which the gas to be measured is introducible.

7. A gas sensor element according to claim 1 , wherein the hollow cavity is an atmospheric chamber into which the atmosphere is introducible.

8. A gas sensor element according to claim 1 , wherein the ceramic porous member only covers the peripheral edge portion of the cavity side electrode while leaving a central portion of the cavity side electrode uncovered.

9. A gas sensor comprising a gas sensor element for detecting a particular gas contained in gas to be measured, wherein the gas sensor element is a gas sensor element according to claim 1 .

Assignees

• Ngk Spark Plug Co

Inventors

• Shimizu Yasumitsu
• Oya Seiji

Classifications

• G01N27/4071 Primary

  using sensor elements of laminated structure · CPC title

• G01N27/41

  Oxygen pumping cells · CPC title

• G01N27/409

  Oxygen concentration cells · CPC title

• G01N27/4072

  characterized by the diffusion barrier · CPC title

• G01N27/4073

  Composition or fabrication of the solid electrolyte · CPC title