Ngk Insulators, Inc.

Mika Kai

Yusuke Watanabe

Ryo Onishi

Saki Suzuki

Takashi Hino

Shiho Iwai

Tomoya Seimori

A sensor element includes: an element base including: a ceramic body made of an oxygen-ion conductive solid electrolyte, and having an inlet at one end portion thereof; at least one internal chamber located inside the ceramic body, and communicating with the inlet under predetermined diffusion resistance; an electrochemical pump cell including an electrode located on an outer surface of the ceramic body, an electrode facing the internal chamber, and a solid electrolyte located therebetween; and a heater buried in the ceramic body; and a porous leading-end protective layer surrounding a first range at least including a leading end surface and a region to be coped with water-induced cracking specified in advance. A single heat insulating space is interposed between the leading-end protective layer and a whole side surface of the element base at least in the above region.

Sensor element

A sensor element includes: an inner protective layer having a porosity of 30% to 65% on two main surfaces; an intermediate protective layer having a porosity of 25% to 80%, which is equal to or smaller than the porosity of the inner layer; and an outer protective layer surrounding an element base on an outermost periphery on the one end portion of the element, and having a porosity of 15% to 30%, which is smaller than the porosity of the intermediate layer, wherein these layers are laminated in this order at least in a range in which the at least one inner chamber is provided in the element base, the outer is in contact with the inner layer in a range in which the at least one inner chamber is not provided, and a difference of porosity between the inner layer and the outer layer is 10% to 50%.

A sensor element includes: an inner protective layer having a porosity of 30% to 65% on two main surfaces; an intermediate protective layer, at least a part of which has contact with the inner layer, and having a porosity of 25% to 80%, which is equal to or smaller than the porosity of the inner layer; and an outer protective layer surrounding an element base on an outermost periphery on the one end portion of the sensor element, having contact with the intermediate and the inner layer, having contact with a leading end surface of the element base or the intermediate layer on the leading end surface, and having a porosity of 15% to 30%, which is smaller than the porosity of the intermediate layer, wherein a difference of porosity between the inner and the outer layer is 10% to 50%.

A sensor element includes: an element base including: a ceramic body made of an oxygen-ion conductive solid electrolyte, and having an inlet at one end portion thereof; at least one internal chamber located inside the ceramic body, and communicating with the gas inlet; and an electrochemical pump cell including an outer electrode, an inner electrode facing the chamber, and a solid electrolyte therebetween, and a porous leading-end protective layer covering a leading end surface and four side surfaces in a predetermined range of the element base on the one end portion, wherein the protective layer has an extension extending into the gas inlet and fixed to an inner wall surface of the ceramic body demarcating the gas inlet, and a gap communicating with the gas inlet is located in the protective layer, with demarcated by a portion of the protective layer continuous with the extension.

A sensor element includes: an element base including: a ceramic body made of an oxygen-ion conductive solid electrolyte, and having a gas inlet at one end portion thereof; at least two internal chambers located inside the ceramic body, and communicating with the gas inlet under predetermined diffusion resistance; an electrochemical pump cell including an electrode located on an outer surface of the ceramic body, an electrode facing the internal chambers, and solid electrolytes located therebetween; and a heater buried in the ceramic body; and a porous leading-end protective layer surrounding a first range at least including a part from a leading end surface to two internal chambers close to the gas inlet of the element base. A single heat insulating space is interposed between the leading-end protective layer and a portion of the element base in which the two internal chambers are located.

A sensor element includes: an element base including: a ceramic body made of an oxygen-ion conductive solid electrolyte, and having a gas inlet at one end portion thereof; at least one internal chamber located inside the ceramic body, and communicating with the gas inlet under predetermined diffusion resistance; an electrochemical pump cell including an electrode located on an outer surface of the ceramic body, an electrode facing the chamber, and a solid electrolyte located therebetween; and a heater buried in the ceramic body, and an leading-end protective layer being porous, and covering a leading end surface and four side surfaces in a predetermined range of the element base on the one end portion. The leading-end protective layer has an extension extending into the gas inlet, and fixed to an inner wall surface of the ceramic body demarcating the gas inlet.

A sensor element includes: an element base including: a ceramic body made of an oxygen-ion conductive solid electrolyte, and having a gas inlet at one end portion thereof; at least one internal chamber located inside the ceramic body, and communicating with the gas inlet under predetermined diffusion resistance; an electrochemical pump cell including an electrode located on an outer surface of the ceramic body, an electrode facing the internal chamber, and a solid electrolyte located therebetween; and a heater buried in the ceramic body, and a leading-end protective layer being porous, and covering a leading end surface and four side surfaces in a predetermined range of the element base on the one end portion. The leading-end protective layer has an extension extending into a widened portion included in the gas inlet, and fixed to an inner wall surface of the widened portion.

A gas sensor includes a structural body made from an oxygen ion conductive solid electrolyte, a gas introduction passage which is formed in the structural body and into which a gas to be measured is introduced, a main adjustment chamber that communicates with the gas introduction passage, and a measurement chamber that communicates with the main adjustment chamber. A buffer space that communicates with the gas introduction passage, and at least two diffusion rate control members that communicate with the buffer space, are provided between the gas introduction passage and the main adjustment chamber. The respective widths Wband Wbof the diffusion rate control members are less than the respective widths Wa, Wc, and Wd of the gas introduction passage, the buffer space, and the main adjustment chamber.

Gas sensor

A first leading-end protective layer surrounding a first range at least including a leading end surface of an element base is included on a side of one end portion. A single heat insulating space is interposed between the first layer and the element base in the first range. The element base further includes a second leading-end protective layer having a larger porosity than the first layer, and located on a whole side surface at least in the first range. An end portion of the first layer opposite the one end portion is a fixed portion to the second layer. A portion where the fixed portion is in contact with the second layer is 10% to 50%, in area, of the first range. The fixed portion and the second layer make an end portion angle of 5&#xb0; to 15&#xb0; in an end portion of the heat insulating space.

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Nagoya, Japan

Mika Kai