Abstract: A metal terminal includes an element contacting portion which is disposed at one end of the metal terminal and is placed in contact with a sensor element, a lead wire retaining member which is disposed at another end of the metal terminal, and crimps and retains lead wires, a positioning member disposed between the one end and the other end and extending in a direction intersecting one direction, the positioning member positioning the metal terminal on a ceramic housing, and a guide member provided integrally with the positioning member at a site between the positioning member and the lead wire retaining member.

Abstract: A gas sensor includes: a sensor element; a plurality of element pads formed on a rear end portion of the sensor element; and a plurality of contact members holding the rear end portion of the sensor element and electrically connected respectively to the plurality of element pads. The plurality of contact members include contact members that each have an outer end surface protruding out from a corresponding one of end surfaces of the sensor element.

Abstract: A sensor element includes: an element body that includes a base part in an elongated plate shape and a measurement-object gas flow part; and a porous protective layer that is formed from one end and covers at least a part in the longitudinal direction of a surface of the element body. The protective layer include: an inner layer; and an outer layer covering the inner layer and a region where the inner layer is not formed. On one principal surface in a region where the inner layer is formed, a first space exists in at least a part between the inner and outer layers, and on the one principal surface in a region where the inner layer is not formed on the one principal surface on which the first space exists, a second space exists in at least a part between the one principal surface and the outer layer.

Abstract: A gas sensor includes: a laminate formed of a plurality of layers including at least one layer of a solid electrolyte; a reference gas chamber formed in the laminate and containing a reference gas; and a reference electrode partially exposed in the reference gas chamber. A portion which is not exposed in the reference gas chamber, of the reference electrode is sandwiched between, among the layers, a first layer and a second layer adjacent to the first layer. When an area of the portion sandwiched between the first layer and the second layer, of the reference electrode is defined as a first area, and an area of a portion exposed in the reference gas chamber, of the reference electrode is defined as a second area, a ratio of the first area to the second area is 0.3 or more.

Abstract: A gas sensor element capable of preventing a decrease in responsiveness despite a protective layer covering a gas introduction opening is provided. A gas sensor element according to an aspect of the present invention includes an element base having a surface in which a gas introduction opening is open, a protective layer, a buffer layer, and a gas introduction layer that is disposed between the element base and the buffer layer. The gas introduction layer covers the gas introduction opening, is in contact with the protective layer, and has a porosity that is 30% or more and is higher by 5% or more than the porosity of the buffer layer.

Abstract: A gas sensor includes an element body, a pump cell, an impedance measurer, and a calculation unit. The pump cell has an inner electrode disposed in a measurement-object gas flow section of the element body, and an outer electrode disposed outside an element body to come into contact with a measurement-object gas, the pump cell being configured to adjust an oxygen concentration in a vicinity of the inner electrode. The impedance measurer performs first measurement to measure a first impedance by applying a voltage having a first frequency to the pump cell, and second measurement to measure a second impedance by applying a voltage having a second frequency higher than the first frequency to the pump cell. The calculation unit calculates the reaction resistance index correlated with the reaction resistance of the pump cell, based on the first and second impedances.

Abstract: The probability of a heater portion of a sensor element being exposed to water is lowered. The sensor element includes a built-in heater that extends in a longitudinal direction and a surrounding housing extending in the longitudinal direction. The heater includes a heat generation portion and a lead portion. The heat generation portion has a front end and a rear end, and is positioned on the same side as a front end portion side of the sensor element. The housing includes an enlarged diameter portion having a diameter of an inner wall that increases in a direction toward the front end of the sensor. The enlarged diameter portion includes a front end portion and a rear end portion. The rear end of the heat generation portion is located closer to the front end of the sensor than the rear end portion of the enlarged diameter portion is.

Abstract: In order to suppress a deterioration in the measurement precision while also reducing the manufacturing cost of a gas sensor element, an aspect of the present invention is directed to a gas sensor element including: a stack formed by stacking a plurality of oxygen ion-conductive solid electrolyte layers, and including an internal space configured to receive a measurement target gas from the outside, a first face adjacent to the internal space, and a second face adjacent to an external space; a first pump electrode provided on the first face; a second pump electrode provided on the second face; a first lead formed on the first face so as to extend from the first pump electrode; and a second lead formed on the second face so as to extend from the second pump electrode and configured to be electrically connected to the first lead. At least one of the first and second leads has a shape with a maximum current density of 3.5 A/mm2 or less.

Abstract: Provided is a gas sensor element that can be used for relatively long period of time without leading to a problem even in a harsh usage environment. A gas sensor element according to one aspect of the present invention includes a laminate in which an internal space is provided, and a first porous layer arranged so as to face the internal space. The first porous layer is in contact with the first solid electrolyte layer and a side face of the spacer layer that faces the internal space, and has a porosity or 10% or more and 50% or less.

Abstract: A sensor element for detecting a specific gas concentration in a measurement-object gas includes: an element body provided with a measurement-object gas flow section therein, the measurement-object gas flow section introducing the measurement-object gas and causing the measurement-object gas to flow therethrough; a reference electrode disposed inside the element body; and a reference-gas introduction section that causes a reference gas to flow to the reference electrode, wherein the reference-gas introduction section has a reference-gas flow path, and one or more preliminary chambers which are disposed in a middle of the reference-gas flow path, and have a diffusion resistance lower than a diffusion resistance of the reference-gas flow path, and at least part of the reference-gas flow path is composed of a porous body so that any of the one or more preliminary chambers does not directly communicate with an outside of the element body.

Abstract: A gas sensor includes: a sensor element; a plurality of element pads formed on a rear end portion of the sensor element; and a plurality of contact members holding the rear end portion of the sensor element and electrically connected respectively to the plurality of element pads. At least one contact member of the plurality of contact members has an end portion having a smaller width Wt than the other contact members.

Abstract: A gas sensor includes a sensor element, an elastic insulating member, a plurality of lead wires, a plurality of metal terminals, and a ceramic housing. The plurality of lead wires are inserted in the elastic insulating member. The plurality of metal terminals each have a first end electrically connected to the sensor element, and a second end electrically connected to a corresponding one of the plurality of lead wires. The ceramic housing includes a plurality of insertion portions each including a through hole in which a corresponding one of the plurality of metal terminals is inserted, and at least one of the plurality of insertion portions has a different height from other insertion portions.

Abstract: A gas sensor includes: a sensor element; a ceramic housing holding a rear end portion of the sensor element and provided with metal terminals electrically connected to the sensor element; and an elastic insulating member that is fixed in the rear of the sensor element and into which a plurality of lead wires electrically connected to the metal terminals are inserted. The elastic insulating member has one or more common spaces formed in a surface of the elastic insulating member that faces the ceramic housing. Two or more of the lead wires are arranged in each common space.

Abstract: A gas sensor includes a sensor element, a tubular body made of metal, and a sealing material. The sensor element has a surface. The tubular body has a through hole which is formed along the axial direction and through which the sensor element is inserted. The sealing material is placed inside the through hole and between the inner peripheral surface of the through hole and the sensor element. The sealing material covers a part of the surface of the sensor element. When the sensor element is viewed in cross section from a second direction perpendicular to a first direction corresponding to the longitudinal direction of the sensor element, the sealing material forms a first inclination angle of not less than 10° and not more than 80° with respect to the surface.

Abstract: A gas sensor has a sensor element, first element pads, second element pads, first contact-point members, and second contact-point members. The sensor element has first and second surfaces that are positioned on opposite sides in a first direction. The first element pads are disposed on the first surface. The second element pads are disposed on the second surface in a quantity greater than that of the first element pads. The first and second contact-point members are connected to the first and second element pads, respectively. The width (Wt) of at least one of the second contact-point members is less than the widths (Wa-Wd) of the rest of the first and second contact-point members.

Abstract: Provided is a gas sensor intended to achieve improved measurement accuracy. A gas sensor according to one aspect of the present invention includes: a gas sensor element including a gas introduction opening and a gas exhaust unit; and a protective member including a plurality of porous layers and configured to cover the gas sensor element. The plurality of porous layers include a first porous layer arranged on the innermost side and a second porous layer arranged on an outer side of the first porous layer. The first porous layer has a higher porosity than the second porous layer. The gas introduction opening and the gas exhaust unit are covered by the first porous layer. The protective member includes, between the gas introduction opening and the gas exhaust unit, a restricting portion configured to restrict the flow of gas.

Abstract: The probability of a heater portion of a sensor element being exposed to water is lowered. The sensor element includes a built-in heater that extends in a longitudinal direction and a surrounding housing extending in the longitudinal direction. The heater includes a heat generation portion and a lead portion. The heat generation portion has a front end and a rear end, and is positioned on the same side as a front end portion side of the sensor element. The housing includes an enlarged diameter portion having a diameter of an inner wall that increases in a direction toward the front end of the sensor. The enlarged diameter portion includes a front end portion and a rear end portion. The rear end of the heat generation portion is located closer to the front end of the sensor than the rear end portion of the enlarged diameter portion is.

Abstract: A sensor element includes a base part including a plurality of oxygen-ion-conductive solid electrolyte layers stacked; a measurement-object gas flow part for introduction and flow of a measurement-object gas through a gas inlet; an inner oxygen pump electrode disposed on an inner surface of the measurement-object gas flow part; and a measurement electrode disposed on the inner surface of the measurement-object gas flow part. The inner oxygen pump electrode includes: a region (A) including an electrode end close to the gas inlet, and a region (B) including an electrode end far from the gas inlet. A content rate of an activity reducing metal in a metal material in the region (A) is higher than that in the region (B). A ratio of the length of the region (A) of the inner oxygen pump electrode to the length of the inner oxygen pump electrode is 15% to 90%.

Abstract: A gas sensor includes: a laminate formed of a plurality of layers including at least one layer of a solid electrolyte; a reference gas chamber formed in the laminate and containing a reference gas; and a reference electrode partially exposed in the reference gas chamber. A portion which is not exposed in the reference gas chamber, of the reference electrode is sandwiched between, among the layers, a first layer and a second layer adjacent to the first layer. When an area of the portion sandwiched between the first layer and the second layer, of the reference electrode is defined as a first area, and an area of a portion exposed in the reference gas chamber, of the reference electrode is defined as a second area, a ratio of the first area to the second area is 0.3 or more.

Abstract: A gas sensor includes a pump electrode disposed in a measured gas flow path, an oxygen detection electrode disposed in the measured gas flow path and containing platinum and zirconia, and a reference electrode disposed in a reference gas chamber where a reference gas exists, and containing platinum and zirconia. A first position of a front end of the pump electrode is located closer to a rear end side than a second position of a front end of the oxygen detection electrode is. When the content of zirconia in the oxygen detection electrode is X [%], and a ratio of a distance between the first and second positions to a longitudinal dimension of the pump electrode is Y [%], Y?141.96e?0.031X is satisfied. The content of zirconia is not lower than that of platinum in the reference electrode.