Denso Corporation

Kabushiki Kaisha Toyota Chuo Kenkyusho

Mitsunobu Nakatou

Takashi Araki

Keigo Mizutani

Takehito Kimata

Yuusuke Toudou

Tadashi Nakamura

Kumi Sawaguchi

On a cross sectional surface Xof a pump electrodein a gas sensor element forming a gas sensor, a noble metal areahaving Pt&#x2014;Au aggregations, a solid electrolyte areahaving solid electrolyte aggregations, a mixture area in which Pt&#x2014;Au alloy and solid electrolyte are distributed, and pores. The mixture areais formed within a range of 30 to 90% in an overall area of the cross sectional surface X, excepting the pores. The pores are formed adjacent to the mixture area

Pump electrode and reference electrode for gas sensor

A gas sensor is equipped with a sensor element which detects a specific gas concentration within a gas that is being measured, a housing having the sensor element disposed in the interior thereof and retained therein, and an element cover disposed at an axial-direction tip end of the housing. The tip of the sensor element is provided with a gas introduction part. The element cover has an inner cover and an outer cover, with a space opened between the inner cover and outer cover. Inner side flow holes provided in the inner cover are disposed closer to an axial-direction base end than is a tapered-diameter step part. The distance between the tip of the sensor element and the inner-side flow holes of the inner cover, with respect to an axial direction, is less than or equal to 1.6 mm.

Gas sensor

A gas sensor includes a solid electrolyte, a gas chamber, a reference gas chamber, a pump cell, a monitor cell, and a sensor cell. The gas chamber has a spatial width Wconstant in a width direction W orthogonal to the direction of flow of a gas in a position where the pump electrode, the monitor electrode, and the sensor electrode are provided on the solid electrolyte. An amount of shift &#x394;Xof a central position Oof a gap S in the width direction W between the monitor electrode and the sensor electrode from a central position Oin the width direction of the pump electrode has relationship of &#x394;X&#x2264;&#xbc; Wwhere the pump electrode has a width W. In addition, positions &#x394;Yof a of a side surface of the monitor electrode and of a side surface of the sensor electrode from the central position Oin the width direction W of the pump electrode have relationship of &#x394;Y&#x2264;&#xbd; W

Gas sensor for detecting concentration of specific gas component

A gas sensor device is equipped with the sensor cell, the pump cell, the inner void space, and the gas inlet. The sensor cell is created by a portion of the solid electrolyte body and a pair of sensor electrodes disposed on the solid electrolyte body. The pump cell is created by a portion of the solid electrolyte body and a pair of pump electrodes disposed on the solid electrolyte body. The inner void space faces the sensor electrode and the pump electrode. If a dimension of said gas inlet in a direction in which the measurement gas flows in the gas inlet is defined as L, a sectional area of the gas inlet taken perpendicular to the direction of flow of the measurement gas in the gas inlet is defined as S, a distance between the gas inlet and the sensor cell is defined as L, and a sectional area of the inner void space taken perpendicular to a direction in which the pump cell and the sensor cell are aligned with each other is defined as S, a relation of 1000&#x2264;(L/S)&#xd7;(L/S)&#x2264;5000 is met.

Gas sensor device

A NOx sensor is provided which decreases a change rate of an oxygen ion current in a sensor electrode and shortens an activation time of the sensor electrode. The NOx sensor is equipped with a solid electrolyte body, a pump electrode working to regulate an oxygen concentration in measurement gas G, and a sensor electrode working to measure the concentration of NOx in the measurement gas G. A metallic component of the sensor electrode is a Pt&#x2014;Rh alloy. The mass ratio of Pt to Rh in the whole of the sensor electrode is Pt:Rh=70:30 to 35:65. The percentage of Rh in the Pt&#x2014;Rh alloy in a surface layer of the sensor electrode is higher than that in the whole of the sensor electrode by an atomic composition percentage of 4 to 10 atom %.

NOx sensor

Provided is a gas sensor element that can increase detection accuracy of a specific gas component concentration by means of a sensor cell by reflecting changes in the operating temperature of a gas sensor element. The gas sensor element is provided with a solid electrolyte body having oxygen ion conductivity, a heater stacked to the solid electrolyte body via a reference gas space, a pump cell adjusting oxygen concentration in a measuring gas space, a sensor cell detecting specific gas component concentration in the measuring gas space, and an electronic conduction detector cell detecting current resulting from electronic conduction due to the heater. The electronic conduction detector cell includes an electronic conductor electrode which is provided to a measuring gas side surface of the solid electrolyte body and covered with an insulator.

Gas sensor element

A gas sensor is provided which constitutes a pump celland a sensor cellusing a single solid electrolyte body, a pump electrode, a sensor electrode, and a reference electrodeand is designed to decrease power consumed by a heater and permit a size thereof to be reduced. A ratio of a minimum distance Lbetween the pump electrodeand the sensor electrodeto a thickness d of the solid electrolyte bodyis set to be three or more, thereby enabling the gas sensorto make the pump celland the sensor cellusing the single solid electrolyte body, the pump electrode, the sensor electrode, and the reference electrode. Only either of the gas chamber or the reference gas chamber is, therefore, located between the solid electrolyte body and the heater, thereby decreasing distances of the pump cell and the sensor cell to the heater. This facilitates the ease with which the heater heats up the pump cell and the sensor cell.

Growing community of inventors

Kariya, Japan

Mitsunobu Nakatou