Electrochemical element and process of manufacturing the same

Claim 2

An electrochemical element, comprising: a planar solid electrolyte body; at least one pair of electrodes including a first electrode and a second electrode which are disposed on said planar solid electrolyte body; means for defining a thin flat space which has a predetermined diffusion resistance to a measurement gas and which communicates with a measurement-gas space in which said measurement gas exists, said first electrode being substantially exposed to said measurement gas in said thin flat space, said means for defining a thin. flat space including two opposed flat surfaces perpendicular to a plane of said thin flat space; and ceramic bridging means disposed in said thin flat space, for bridging a gap between said two opposed flat. surfaces and thereby substantially determining a thickness of said thin flat space.

Claim 3

An electrochemical element according to claim 1, wherein said first electrode is spaced a predetermined distance away from an inlet of said thin flat space through which said measurement gas is introduced into said thin flat space, said ceramic bridging means being disposed at least in an area of said thin flat space corresponding to said predetermined distance.

Claim 4

An electrochemical element according to claim 1 or 2, wherein one of opposite major surfaces of said planar solid electrolyte body on which said first electrode is disposed comprises one of said two opposed flat surfaces of said means for defining a thin flat space.

Claim 5

An electrochemical element according to claim 3, further comprising another solid electrolyte body having a major surface which comprises the other of said two opposed flat surfaces of said means for defining a thin flat space.

Claim 6

An electrochemical element according to claim 1 or 2, further comprising a protective layer disposed so as to cover said first electrode on said planar solid electrolyte body, one of opposite major surfaces of said protective layer remote from said first electrode comprising one of said two opposed flat surfaces of said means for defining a thin flat space.

Claim 7

An electrochemical element according to claim 5, further comprising another layer made of a material similar to that of said protective layer, one of opposite major surfaces of said another layer on the side of said protective layer comprising the other of said two opposed flat surfaces of said means for defining a thin flat space.

Claim 8

An electrochemical element according to claim 1, wherein said means for defining a thin flat space comprises two members which have said two opposed flat surfaces and which are made of substantially the same material, said ceramic bridging means being made of the same material as the material of said two members having said two opposed flat surfaces.

Claim 9

An electrochemical element according to any one of claims 1-7, wherein said ceramic bridging means consists of a plurality of mutually spaced-apart ceramic members which are disposed at least in an area of said thin flat space adjacent to an inlet of said thin flat space through which said measurement gas is introduced into said thin flat space.

Claim 10

An electrochemical element according to any one of claims 1-8, wherein said ceramic bridging means consists of a plurality of ceramic grains having a diameter which is substantially equal to the thickness of said thin flat space.

Claim 11

An electrochemical element according to any one of claims 1-9, wherein said planar solid electrolyte body, and said first and second electrodes constitute a first electrochemical cell, and further comprising a second electrochemical cell which includes another planar solid electrolyte body, and another pair of electrodes, said thin flat space being formed between said first and second electrochemical cells.

Claim 12

ll. A process of manufacturing an electrochemical element which comprises a planar solid electrolyte body, at least one pair of electrodes including a first and a second electrode which are disposed. on said planar solid electroyte body, means for defining a thin flat space which has a predetermined diffusion resistance to a measurement gas and which communicates with a measurement-gas space in which said measurement gas exists, said first electrode being substantially exposed to said thin flat space, said means for defining a thin flat space including two opposed flat surfaces perpendicular to a plane of said thin flat space, and ceramic bridging means disposed in said thin flat space, for. bridging a gap between said two opposed flat surfaces and thereby substantially determining a thickness of said thin flat space, said process comprising the steps of: preparing a mixture which consists of a filler material which disappears upon firing thereof, and ceramic grains; applying said mixture in the form of a layer having a predetermined thickness, so as to occupy at least a portion of said thin flat space to be formed; firing said layer of said mixture so that said filler material disappears and contributes to forming a part of said portion of said thin flat space, while said ceramic grains are fired into said ceramic bridging means which connects said two opposed flat surfaces to each other and substantially detemines the thickness of said thin flat space over an entire area of said thin flat space from an inlet thereof to extremities thereof remote from said inlet.

Claim 13

ll. A process of manufacturing an electrochemical element which comprises a planar solid electrolyte body, at least one pair of electrodes including a first and a second electrode which are disposed. on said planar solid electroyte body, means for defining a thin flat space which has a predetermined diffusion resistance to a measurement gas and which communicates with a measurement-gas space in which said measurement gas exists, said first electrode being substantially exposed to said thin flat space, said means for defining a thin flat space including two opposed flat surfaces perpendicular to a plane of said thin flat space, and ceramic bridging means disposed in said thin flat space, for. bridging a gap between said two opposed flat surfaces and thereby substantially determining a thickness of said thin flat space, said process comprising the steps of: preparing a mixture which consists of a filler material which disappears upon firing thereof, and ceramic grains; applying said mixture in the form of a layer having a predetermined thickness, so as to occupy at least a portion of said thin flat space to be formed; firing said layer of said mixture so that said filler material disappears and contributes to forming a part of said portion of said thin flat space, while said ceramic grains are fired into said ceramic bridging means which connects said two opposed flat surfaces to each other and substantially detemines the thickness of said thin flat space over an entire area of said thin flat space from an inlet thereof to extremities thereof remote from said inlet.

Claim 14

A process of manufacturing an electrochemical element according to claim 11, further comprising providing said two opposed flat surfaces by forming two ceramic members of substantially the same material and firing said two ceramic members at a firing temperature, said ceramic grains being fired into said ceramic bridging means at a temperature lower than said firing temperature of said two ceramic members.

Claim 15

A process of 'manufacturing an electrochemical element according to claim 11 or 12, wherein said ceramic grains which form said ceramic bridging means have a diameter substantially equal to the thickness of said thin flat space.