Ngk Insulators, Inc.

Yusuke Watanabe

Takayuki Sekiya

Shotaro Niizuma

Toshihiro Hirakawa

Mika Kai

Hayami Aota

Takao Murase

Ryo Onishi

Shiho Iwai

Masashi Yasui

Saki Suzuki

Takashi Hino

Shota Kageyama

Daichi Ichikawa

Yuki Nakayama

Rui Sakaguchi

Kirari Takahashi

Taku Okamoto

Tomoya Seimori

Ryo Hashikawa

Yasuhide Kojima

Tetsuya Ishikawa

Kengo Terasawa

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.

Gas sensor

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.

Gas sensor element

A gas sensor includes: a laminate including at least one layer made of a solid electrolyte; a measured gas flow path formed in the laminate; and a pump electrode exposed in the measured gas flow path. In a part of a rear end side region, the pump electrode is sandwiched between a first layer and a second layer or is covered with a covering layer formed on the inner surface of the measured gas flow path. The area of a portion exposed in the measured gas flow path, of the pump electrode is 4 mmor more. The area of a portion exposed in the measured gas flow path, of the front end side region is larger than the area of a portion exposed in the measured gas flow path, of the rear end side region.

A gas sensor detects a specific gas concentration in a measurement-object gas and includes an element body and one or more pump cells. The element body includes an oxygen-ion-conductive solid electrolyte layer and is provided with a measurement-object gas flow section therein. The measurement-object gas flow section receives a measurement-object gas and allows the measurement-object gas to flow therethrough. The one or more pump cells each have an inner electrode and an outer pump electrode and pump out oxygen from around the inner electrode to around the outer pump electrode. The inner electrode is disposed in the measurement-object gas flow section and contains a catalytically-active noble metal. At least one pump cell of the one or more pump cells pumps out the oxygen by applying a repeatedly on-off controlled pump current between a measurement electrode and the outer pump electrode.

A sensor element includes: a base part containing an oxygen-ion conductive solid electrolyte as a constituent material; at least one internal space into which a measurement gas is introduced; and at least one pump cell including an internal electrode disposed to face the at least one internal space, an out-of-space pump electrode disposed at a location other than the at least one internal space, and a portion of the base part located between these electrodes, the internal electrode includes: an upper layer consisting of a noble metal, the solid electrolyte, and a pore; and a lower layer consisting of the noble metal and the solid electrolyte, and a volume ratio of the solid electrolyte in the lower layer is greater than a volume ratio of the solid electrolyte in the upper layer.

Sensor element of NOsensor and method for manufacturing sensor element of NOsensor

A gas sensor includes a sensor element and a controller. The sensor element includes an element body provided with a measurement-object gas flow section therein, a measurement electrode disposed in the measurement-object gas flow section, an outer pump electrode provided in the element body so that the outer pump electrode comes into contact with a measurement-object gas, a reference electrode, a reference-gas introduction section that causes a reference gas to flow to the reference electrode, and a reference-gas adjustment pump cell constituted by including the outer pump electrode and the reference electrode. The controller performs a moisture-absorption-state diagnosis process of diagnosing a moisture absorption state around the reference electrode based on a pump current flowing through the reference-gas adjustment pump cell when the reference-gas adjustment pump cell is controlled to pump out oxygen from a periphery of the reference electrode to a periphery of the outer pump electrode.

Gas sensor and method of diagnosing moisture absorption state of gas sensor

A casing of a gas sensor having a reference gas space therein includes: an outer tube into which an end portion of a sensor element protrudes; and a seal member fit into an end portion of the outer tube to seal the reference gas space, the sensor element includes: a first electrode lead portion including a first electrode lead to electrically connect an outside and at least one out-of-space pump electrode and a first lead insulating layer covering the first electrode lead; and a second electrode lead portion including a second electrode lead that can electrically connect the outside and a measurement electrode and a second lead insulating layer covering the second electrode lead, and A/B<1.00, where A (cm) is diffusion resistance of the first electrode lead portion, B (cm) is diffusion resistance of the second electrode lead portion.

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 one end part in a longitudinal direction of the base part; a main pump cell including an inner main pump electrode disposed on an inner surface of the measurement-object gas flow part, and an outer pump electrode; a target-gas-decomposing pump cell including a target-gas-decomposing pump electrode disposed at a position farther from the one end part than the inner main pump electrode, and an outer pump electrode; a residual-oxygen-measuring pump cell including a residual-oxygen-measuring electrode disposed at a position farther from the one end part than the inner main pump electrode, and an outer pump electrode; and a reference electrode. The target-gas-decomposing pump electrode comprises a metal material that has catalytic activity of decomposing a target gas to be measured.

Sensor element and gas detection method using sensor element

A sensor element includes: a base part containing an oxygen-ion conductive solid electrolyte as a constituent material; at least one internal space into which a measurement gas is introduced; and at least one pump cell including an internal electrode disposed to face the internal space, an out-of-space pump electrode disposed at a location other than the internal space, and a portion of the base part located between these electrodes, the internal electrode includes a noble metal, the solid electrolyte, and a pore, and, in the internal electrode, a degree of variation of a boundary of a first region formed of the base part or the solid electrolyte contiguous with the base part and a second region occupied by the noble metal and the pore in a thickness direction of the element is 0.5 μm or more and 6.5 μm or less.

Sensor element of NOx sensor

A sensor element includes a base part containing a solid electrolyte as a constituent material; at least one internal space into which a measurement gas is introduced; and at least one pump cell including an internal space electrode disposed to face the internal space, an out-of-space pump electrode disposed at a location other than the internal space, and a portion of the base part located between these electrodes, the internal space electrode includes a noble metal, the solid electrolyte, and a pore, and, in the internal space electrode, a ratio of a length of a boundary of a first region formed of the base part or the solid electrolyte contiguous with the base part and a second region occupied by the noble metal and the pore to a length of a boundary of the solid electrolyte and the internal space electrode is 1.1 or more.

Sensor element of gas sensor

A gas sensor element includes an element body including an oxygen-ion-conductive solid electrolyte layer; and a protective layer that covers at least part of the element body, and has a thermal conductivity ratio R of 1.6 or higher, the thermal conductivity ratio R (=λs/λt) being a surface direction thermal conductivity λs [W/m K] to a thickness direction thermal conductivity λt [W/m K].

Gas sensor element and gas sensor

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.

A controller of the gas sensor can perform diagnostic processing of diagnosing a situation of control to the gas sensor in a case that the gas sensor in an operation state is determined to satisfy a predetermined diagnostic condition and adjustment processing of adjusting a condition for controlling the gas sensor in accordance with a result of diagnosis. In the diagnostic processing, a main pump voltage and a diagnostic threshold as a value of a voltage not causing decomposition of NOx in the main pump cell are compared. In the adjustment processing, temperature adjustment processing to cause, in a case that the main pump voltage is diagnosed to be equal to the threshold or more, the main pump voltage to be less than the threshold, at least in a way that the heater part increases the element driving temperature in the operation state by a predetermined increase amount is performed.

Gas sensor and gas sensor operation control method

A sensor element includes: an element base including a gas distribution part communicating from a gas inlet; and a leading-end protective layer including an inner layer covering an end portion and four side surfaces of the element base and an outer layer covering the inner layer and having a lower porosity than the inner layer, and a total thickness representative value, defined as an average of total thicknesses of the protective layer at a plurality of positions including a starting point, an intermediate position, and an innermost end of the gas distribution part, is 250 μm or more, and a film thickness variation degree, defined as a ratio of a difference between a maximum value and a minimum value of the total thicknesses with respect to the total thickness representative value when the value is based at 100, is 20 or less.

In a sensor element for a limiting-current type gas sensor measuring concentration of NOx in a measurement gas, an inner pump electrode located to face a first internal space communicating with a gas inlet through which the measurement gas is introduced from an external space under predetermined diffusion resistance is made of a cermet of a Pt—Au alloy and zirconia, and the inner pump electrode is located, from among surfaces defining the first internal space, at least on a surface farthest from a heater part in a thickness direction of the element, and is not located on a surface closest to the heater part in the thickness direction.

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Nagoya, Japan

Yusuke Watanabe