Ngk Insulators, Inc.

Yosuke Adachi

Koichi Masuda

Tomoya Seimori

Takeshi Omori

Miyoshi Makino

Takashi Hino

Ryo Onishi

Kenji Isaka

Tetsuya Ishikawa

Jumpei Tanaka

A gas sensor includes a sensor element, an inner protective cover having one or more element chamber inlets and including a first member and a second member, and an outer protective cover having one or more outer inlets. A first gas chamber between the outer protective cover and the inner protective cover has a first space and a second space. A cross-sectional area Cs that is a flow channel cross-sectional area in the second space when the measurement-object gas passes from an outside of the second member toward an inside of the second member just above the second member is greater than or equal to 14.0 mm, and a cross-sectional area Ds that is a cross-sectional area perpendicular to a circumferential direction of the inner protective cover in the second space is greater than or equal to 0.5 mmand less than or equal to 6.4 mm.

Gas sensor and protective cover

Gas concentration detection sensor

A gas sensor includes a sensor element, an inner protective cover having inside a sensor element chamber and having an element chamber inlet and an element chamber outlet, and an outer protective cover having an outer inlet and an outer outlet. A total cross-sectional area A [mm] of the outer inlet, a total cross-sectional area B [mm] of the element chamber inlet, a total cross-sectional area C [mm] of the element chamber outlet, and a total cross-sectional area D [mm] of the outer outlet satisfy B&#x3e;A&#x3e;C&#x3e;D, a cross-sectional area ratio A/D is greater than a value of 2.0 and less than or equal to a value of 5.0, and A&#xd7;B&#xd7;C&#xd7;D is greater than or equal to a value of 3000 and less than or equal to a value of 8500.

In a gas sensor, a powder compact seals a void space between an inner peripheral surface of metal-made main hardware and a sensor element, and the inner peripheral surface has arithmetic average roughness of 0.5 to 5 &#x3bc;m. The gas sensor includes supporters, which are arranged in a penetration hole of the main hardware, which allow the sensor element to penetrate therethrough, and which press the powder compact in sandwiching relation from both sides in an axial direction. A surface of at least one of the supporters has the arithmetic average roughness of not more than 0.5 &#x3bc;m.

Gas sensor

A method of measuring adhesive strength between an element body and a porous protection layer that are included in a sensor element includes (a) a step of holding a portion of the element body where the porous protection layer is absent with an elastic force exerted by a holding jig, and placing a peeling jig at a position between the porous protection layer and the holding jig in the longitudinal direction such that the element body is allowed to move in the longitudinal direction while the porous protection layer is prevented from moving in the longitudinal direction toward the holding jig; and (b) a step of moving, after the step (a), the peeling jig pushes the porous protection layer in the longitudinal direction, and measuring the adhesive strength of the porous protection layer.

Method of measuring adhesive strength

An inner protective coverof a gas sensor forms an element-chamber inlethaving a first outside opening, a second outside opening, and an element-side opening. The second outside openingis disposed such that the path of a measurement-object gas from the first outside openingto the element-side openingof the element-chamber inletcommunicates in the middle thereof with a first gas chamber, and that there is a path shorter than the shortest path of the measurement-object gas extending from an outer inletthrough the first outside openingto a gas inlet

In a gas sensor, a powder compactseals a void space between an inner peripheral surfaceof metal-made main hardwareand a sensor element, and the inner peripheral surfacehas arithmetic average roughness Ra of 0.5 to 5 &#x3bc;m. The gas sensorincludes supportersand, which are arranged in a penetration hole of the main hardware, which allow the sensor elementto penetrate therethrough, and which press the powder compactin sandwiching relation from both sides in an axial direction. A surface of at least one of the supportersandhas the arithmetic average roughness Ra of not more than 0.5 &#x3bc;m.

In a holding portion of a contact fitting, in a state before crimping of core wires, the thickness of a first distal end portion and the thickness of a second distal end portion are both 70% or less of the thickness of the bottom portion. The thicknesses are both smaller than the diameter of core wires of a lead wire to be crimped. The first distal end portion and the second distal end portion are formed by compression processing. Using the holding portion, a first side portion and a second side portion are curved such that they face the bottom portion, and the plurality of core wires are surrounded and crimped with the bottom portion, the first side portion, and the second side portion.

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Nagoya, Japan

Yosuke Adachi