Ngk Spark Plug Company, Limited

Toru Iwano

Masaki Onkawa

Takeshi Mitsuoka

Kuniharu Tanaka

Satoshi Teramoto

Masaki Mizutani

Shun Sakuma

Tatsuhiko Muraoka

Shigehiro Ohtsuka

Shigehiro Otsuka

Sigehiro Otsuka

A gas sensor element has a protection layer smaller in heat capacity than a conventional protection layer formed by a dipping process. A gas sensor includes the gas sensor element. The gas sensor element is manufactured by a method of manufacturing. The gas sensor element includes at least one space formed between a protection layer and an element body. The space is positioned over at least one of four vertexes of a forward end of the element body at a location at which the thickness of the protection layer is likely to become small. Therefore, it is possible to restrain breakage of the vertexes of the forward end of the element body which could otherwise result from thermal shock stemming from adhesion of water. The protection layer of the gas sensor element can be reduced in thickness and thus in heat capacity as compared with a conventional protection layer.

Gas sensor element, gas sensor, and method of manufacturing gas sensor element

A gas sensor element in an air/fuel ratio sensor includes an element body and a protection layer having two layers (a first layer and a second layer). The gas sensor element has at least one separation portion in the form of a space between the first layer and the second layer. The gas sensor element can temporarily accumulate, in the at least one separation portion, water which adheres to the surface of the protection layer and penetrates into the protection layer. Thus, as compared with a protection layer which is identical in thickness to the protection layer, but does not have separation portions, water adhering to the protection layer is less likely to reach the element body. Therefore, there can be restrained breakage of an end of the element body which could otherwise result from thermal shock stemming from adhesion of water.

A gas sensor element comprises an elongated plate-like element including, at a forward end portion, a detecting section comprising a solid electrolyte body having an outer surface and a back surface, a detection electrode on the outer surface and a reference electrode on the back surface, and a porous layer covering the detection electrode. The coating layer includes a first protection layer entirely covering the detecting section, and a second protection layer circumferentially covering the first protection layer and extending at least from a forward end of the first protection layer to a position located rearward of the porous layer. The thickness of the first protection layer on the porous layer is larger than that of the first protection layer rearward of the porous layer. The thickness of the second protection layer rearward of the porous layer is larger than that of the second protection layer above the porous layer.

Gas sensor with porous protection layers

A gas sensor element and a gas sensor incorporating the gas sensor element. The gas sensor element () includes a detection portion () including a solid electrolyte body () and a pair of electrodes () and () disposed on the solid electrolyte body; and a porous protection layer () covering the detection portion. The porous protection layer includes an inner porous layer () and an outer porous layer (). The inner porous layer has a higher porosity than the outer porous layer. Further, the inner porous layer contains, as main components, ceramic particles (), and ceramic fiber filaments (), and the amount of the ceramic fiber filaments is 25 to 75 vol % based on the total amount of the ceramic particles and the ceramic fiber filaments taken as 100 vol %.

Gas sensor element and gas sensor

A gas sensor element () including a detection portion () including a solid electrolyte body () and a pair of electrodes () and () disposed on the solid electrolyte body; and a porous protection layer () covering the detection portion. The porous protection layer includes an inner porous layer () and an outer porous layer (); the inner porous layer is higher in porosity than the outer porous layer; the inner porous layer contains, as main components, ceramic particles (), and ceramic fiber filaments () which are mainly formed of a ceramic material and which have a mean fiber length of 70 to 200 &#x3bc;m; and the amount of the ceramic fiber filaments is 25 to 75 vol % on the basis of the total amount of the ceramic particles and the ceramic fiber filaments, the total amount being taken as 100 vol %.

Gas sensor element, and gas sensor

A gas sensor element () includes a laminate of a detection element () and a heater (), and a porous protection layer () covering a forward end portion thereof. The laminate has a measuring chamber () into which a gas-to-be-measured is introduced via a diffusion resistor (). The porous protection layer includes an inner porous layer (), and an outer porous layer (). The inner porous layer has a higher porosity than the outer porous layer and the diffusion resistor. As viewed in a plurality of 100 &#x3bc;m&#xd7;100 &#x3bc;m regions ato aand bto bon sections of the inner porous layer and the diffusion resistor, respectively, a pore diameter greater than the greatest pore diameter Cin the regions of the diffusion resistor exists in each of the regions of the inner porous layer.

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Komaki, Japan

Toru Iwano