Ngk Spark Plug Company, Limited

Niterra Co., Ltd.

Yuji Shimazaki

Kentaro Mori

Takayoshi Atsumi

Yasuhiro Fujita

Hironari Furuta

Kunihiko Yonezu

Masayuki Yoshida

A gas sensor including: a sensor element; a metallic shell; and a single-wall tubular protector. The protector has a gas introduction hole and a gas discharge hole disposed on a forward end side in relation to the gas introduction hole. The metallic shell has a fixing portion whose outer surface is fixed to a pipe, and a larger-diameter tool engagement portion located on a rear end side of the fixing portion and used to attach the gas sensor. A distance Lin the axial O direction between the gas introduction hole and the gas discharge hole is greater than a distance Lin the axial direction between the tool engagement portion and the gas introduction hole; and a forward end (a) of the sensor element is located on the forward end side in relation to the gas introduction hole.

Gas sensor and gas sensor attached structure

A gas sensor includes a sensing element, a metal shell that is tubular and that surrounds the sensing element, and a protector made of a metal and fixed to the metal shell. A back end portion of the protector is joined to an outer surface of the metal shell to form a joined portion. A coefficient of thermal expansion of a material of the protector at 800 degrees Celsius is higher than a coefficient of thermal expansion of a material of the metal shell at 800 degrees Celsius. In a cross section of a portion of the gas sensor including the joined portion, a minimum distance tbetween the outer surface of the metal shell and an outer surface of the protector and a minimum distance tbetween the outer surface of the metal shell and an inner surface of the metal shell satisfy 0.6&#x2264;(t/t)&#x2264;2.0.

Gas sensor

A protector has a two-stage structure that includes a large-diameter portion and a small-diameter portion. The large-diameter portion includes a cylindrical first peripheral wall and a first front end wall. The small-diameter portion includes a cylindrical second peripheral wall connected to the first front end wall and a second front end wall connected to a front end portion of the second peripheral wall. Opening portions are not formed in the first and second peripheral walls. First opening portions, which are opened toward only first recessed portions and an inner surface of the first peripheral wall, are formed at the first front end wall. A second recessed portion and second opening portions, which are formed in the second recessed portion and are opened toward an inner surface of the second peripheral wall, are formed in the second front end wall.

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Nagoya, Japan

Yuji Shimazaki