Gas sensor
AssigneeNgk Spark Plug Co., Ltd.
InventorsKouji Matsuo, Shoji Akatsuka, Shoichi Ohtsuki, Satoshi Ishikawa
Life of this patent
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Abstract
In a gas sensor, a casing which accommodates a sensing element includes an inner cylindrical member and an outer cylindrical member which are caulked together by means of a caulked portion. The Vickers hardness H1 of the inner cylindrical member is Hv 250 to 430; the Vickers hardness H2 of the outer cylindrical member is Hv 160 to 330; and the hardness difference “H1-H2” is not less than 30. Through employment of the above ranges of H1 and H2, the caulked portion can maintain good airtightness even in a working environment involving, for example, thermal shocks.
Claims8
A gas sensor comprising:
- a sensing element having a sensing portion adapted to detect a component in a gas being measured;
- a ceramic separator having a flange-shaped support portion at an axially intermediate position;
- and
- a casing covering the sensing element while the gas being measured is permitted to flow through the casing to the sensing portion, the casing including at least two axially adjacent members, the at least two axially adjacent members having an inner member having a tip end portion and an outer member having an end portion, the tip end portion of the inner member disposed within the corresponding end portion of the outer member to thereby form an overlap zone, an inner surface of the tip end portion directly abutted to an outer surface of the flange-shaped support portion, wherein the inner member has a Vickers hardness H1 in the range of from Hv 250 to 430, the outer member has a Vickers hardness H2 in the range of from Hv 160 to 330, and the hardness difference “H1−H2” therebetween is not less than 30, and wherein in the overlap zone, the inner member and the outer member are circumferentially caulked in an airtight manner.
Dependencies are inferred from the claim text.