Denso Corporation

Denso Corpora Tion

Yusuke Todo

Mitsunobu Nakato

Takashi Araki

Hiroki Ichikawa

Ryozo Kayama

Yuki Murayama

Manabu Yoshidome

Hiroaki Yoto

Tatsuya Yoshikawa

Yuji Kawasaki

A gas sensor includes a sensor element including a solid electrolyte, a gas chamber, a pump electrode, a sensor electrode, and a reference electrode. The pump electrode and sensor electrode are provided in the solid electrolyte in a state in which the pump electrode and the sensor electrode are housed in the gas chamber. The reference electrode is provided in the solid electrolyte. The pump electrode and the sensor electrode contain Au. Au content in a surface layer is equal to or greater than 1 mass % and higher than Au content in a reference layer. The surface layer is an area from a surface of the sensor electrode to a depth of 0.3 nanometers. The reference layer is an area located at depths ranging from 2 or more to 3 or less nanometers beneath the surface of the sensor electrode.

Gas sensor

A gas sensor element including a solid electrolyte body, a sensor electrode, and a reference electrode is provided. The solid electrolyte body has oxygen ion conductivity and includes a measurement gas surface to be exposed to a measurement gas introduced from the exterior and a reference gas surface to be exposed to a reference gas introduced from the exterior. The sensor electrode is provided on the measurement gas surface of the solid electrolyte body. The reference electrode is provided on the reference gas surface of the solid electrolyte body. The sensor electrode includes a porous body containing a solid electrolyte having oxygen ion conductivity and a precious metal, the peak pore size of the sensor electrode being 0.03 &#x3bc;m to 0.3 &#x3bc;m.

Gas sensor element and gas sensor

It is to determine whether a temperature rise condition of a first cell or a second cell is satisfied based on whether a first parameter has exceeded a predetermined first threshold or a second parameter has exceeded a predetermined second threshold. After satisfaction of the temperature rise condition, it is to determine that an exhaust gas sensor is in an active state upon determination that a corresponding time condition is satisfied.

Control apparatus

A microcomputer includes a voltage application unit that selectively applies a normal voltage and a removal voltage higher than the normal voltage to a first cell of the exhaust gas sensor. The first cell is configured to remove, based on the removal voltage, oxygen in an exhaust gas from an internal combustion engine. The microcomputer includes an element temperature measurement unit that measures an element temperature parameter indicative of a temperature of the first cell. The microcomputer includes a termination determination unit that determines, based on the element temperature parameter, a termination time of terminating the application of the removal voltage to the first cell by the voltage application unit.

A gas sensor element of the present disclosure includes a measurement gas chamber, a solid electrolyte body, and a sensor electrode. The sensor electrode has a noble metal region which contains at least Rh and Pt, an electrolyte region which is formed by a solid electrolyte, and a mixed region in which the noble metal and the solid electrolyte are mixed. With respect to a correlation curve which represents a correlation between a mass percentage concentration c of Rh and a thickness d of the mixed region, when a reaction resistance to a measured gas in the sensor electrode is 40 k&#x3a9;, the concentration c of Rh and the thickness d are set so that at coordinates (c, d), the concentration c has a positive coordinate point and the thickness d has a positive coordinate point.

Gas sensor element and gas sensor unit

A gas sensor device is equipped with a diffusion controlling portion, a pump cell, and a sensor cell. The diffusion controlling portion is formed to face a major surface of a solid electrolyte body and works to control a rate of diffusion of a measurement gas entering a measurement gas chamber. The pump cell has a pump electrode which contains gold and is formed on the major surface. The pump electrode is located downstream of the diffusion controlling portion in a gas flow direction. The pump cell works to regulate a concentration of oxygen in the measurement gas upon application of voltage to the pump electrode. The sensor cell has a sensor electrode formed on the major surface downstream of the diffusion controlling portion in the gas flow direction. The sensor cell works to measure a concentration of nitrogen oxide contained in the measurement gas upon application of voltage to the sensor electrode. The pump electrode is disposed upstream of the sensor electrode at a distance of 0.2 mm or more downstream away from the diffusion controlling portion in the gas flow direction. This enhances the accuracy in measuring the concentration of NOx.

A gas sensor element of the present disclosure includes a measurement gas chamber, a pump cell, a sensor cell including a sensor electrode, and a pump-cell controller. When the gas sensor element is activated before detecting a concentration of a gas, in order to remove oxygen occluded in the sensor electrode, the pump-cell controller applies a removing voltage to the pump cell so that a reducing gas is generated. The sensor electrode has a plurality of noble metal regions which are made of noble metal and electrolyte regions which are distributed so that an interface is generated between a part of a solid electrolyte body and the plurality of noble metal regions. The sensor electrode has an open pore which extends from an electrode surface of the sensor electrode and reaches at least one of the plurality of noble metal regions.

A gas sensor includes a sensor element. The sensor element includes; a solid electrolyte body that has oxygen ion conductivity and includes a first main surface exposed to a gas to be measured and a second main surface exposed to a reference gas; a sensor electrode that is provided on the first main surface and detects a specific gas component in the gas to be measured; and a reference electrode that is provided on the second main surface. The sensor electrode is made of a Pt&#x2014;Rh alloy that contains 30 mass % to 70 mass % Pt and 70 mass % to 30 mass % Rh, when an overall noble metal component is 100 mass %. A variation amount of the Rh content of the Pt&#x2014;Rh alloy from an outermost surface to a depth of 350 nm in a thickness direction of the sensor electrode is within a range of up to 10 mass %.

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Kariya, Japan

Yusuke Todo