Denso Corporation

Shota Imada

Tomotaka Mouri

Toru Takeuchi

Satoshi Suzuki

Hirofumi Suzuki

Makoto Nakae

Hiroshi Araki

Takumi Ushikubo

The sensor element of a gas sensor includes an element body, a surface protective layer provided at the outermost surface position of a tip portion of the element body, in the longitudinal direction of the element body, and an internal protective layer provided between the surface protective layer and the element body. The internal protective layer has a lower thermal conductivity and a higher average porosity than the surface protective layer, and is disposed between the surface protective layer and the element body. In the internal protective layer, a first protective layer portion of the internal protective layer is located on a side that faces the heater, and at least the base position is positioned closer in the longitudinal direction to the tip end of the element body than is the maximum temperature position on the element body.

Gas sensor and method of manufacture thereof

A gas sensor element for detecting a specific gas component in a measured gas, comprising: an element body in the form of a long plate having a gas detection part at an end thereof on a distal end face side in a longitudinal direction; and a porous protective layer covering an outer periphery of the end on said end face side of the element body, wherein in a cross section including two adjacent ones of the end face and side faces connected to the end face, an outer surface of the protective layer facing an element corner where the two faces meet has a shape with a corner part, and a ratio of an assumed diameter of a water droplet contained in the measured gas in a use environment to an effective length of the corner part in the cross section is equal to or larger than 1.5.

Gas sensor element and gas sensor

A gas sensor includes a sensor element, and the sensor element includes a bottomed tubular solid electrolyte, a detection electrode provided on an outer surface of the solid electrolyte, a reference electrode provided on an inner surface of the solid electrolyte. The detection electrode of the sensor element includes a detection electrode section provided at a position on a tip side of an axial direction, an attachment electrode section provided at a position on a base end side of the axial direction, and a lead electrode section provided at a position where the detection electrode section is connected to the attachment electrode section. An insulating layer is provided between a tube of the solid electrolyte and each of the attachment electrode section and the lead electrode section.

Gas sensor

A gas sensor element comprising a long plate-like element body and a porous protective layer protecting a surface of the element body, wherein the element body has a gas detection part at an end thereof on one end face side in a longitudinal direction, and the protective layer includes an end face part covering the one end face in laminate, side face parts covering side faces connected to the one end face in laminate, and corner parts where two adjacent ones of the end face part and the side face parts meet. An outer surface of one or more of the end face part and the side face parts has a concave shape that is smoothly continuous with the corner parts and configured such that a layer thickness increases toward the corner parts.

An alumina sintered body has a main phase made of alumina crystals, a first dispersed phase made of MgAlOdispersed in the main phase, and a second dispersed phase made of SiOand/or CaO dispersed in the main phase. A content ratio of the main phase is within a range from not less than 98% to less than 98%. The alumina sintered body satisfies a relationship of 100&#xd7;I/I&#x2267;5.5%, where Iindicates a maximum peak height intensity derived from alumina, and Iindicates a maximum peak height intensity derived from MgAlOin a X-ray diffraction of the alumina sintered body. An area ratio of the second dispersed phase on a surface of the alumina sintered body is not more than 15.2%. A spark plug has a central electrode, a ground electrode and an insulator made of the alumina sintered body having the specific features previously described.

Alumina sintered body and spark plug using the same

An alumina sintered body contains a main phase consisting of alumina crystal, and crystalline phases dispersed in the main phase. The crystalline phases consist of at least one selected from a group consisting of MgAlO, 2MgO.2AlO.5SiO, 2MgO.SiOand MgO.SiO. The average grain size of the crystalline phases is 0.4 &#x3bc;m to 5.3 &#x3bc;m. In an arbitrary area having a size of 100 &#x3bc;m&#xd7;100 &#x3bc;m in a cross-section of the alumina sintered body, the number of the crystalline phases having grain sizes 1 &#x3bc;m to 5 &#x3bc;m is 8 to 412.

Growing community of inventors

Kariya, Japan

Shota Imada