Ngk Insulators, Inc.

Taku Okamoto

Osamu Nakasone

Yuki Nakayama

Kosuke Monna

Noriko Hirata

Nobukazu Ikoma

Soichiro Yoshida

Kunihiko Nakagaki

Takashi Ryu

Nobuhiko Mori

Takayuki Sakurai

Ryo Hashikawa

Yoshinobu Nakada

Makoto Ohmori

Toshihiro Yoshida

Yuichiro Kondo

Yusuke Watanabe

Takayuki Sekiya

Hiroshi Hayashi

Daichi Ichikawa

Yuto Yamada

Akira Sasaki

Masaru Nishitoba

A sensor element includes first to third chambers communicating sequentially from a gas inlet, voltages are intermittently applied across inner electrodes facing the respective chambers and a reference pump electrode to perform pumping of oxygen between a measurement gas and the reference pump electrode being in contact with a reference gas, thereby to reduce HO and COin the measurement gas into Hand CO in the first chamber, to oxidize Hinto HO in the second chamber, to oxidize CO into COin the third chamber, and to identify a concentration of HO and a concentration of CObased on a pumping-in current at the time when electromotive force between an inner electrode and the reference pump electrode during non-application of a voltage is maintained at a target value.

Gas sensor and concentration measurement method using gas sensor

A gas sensor includes a sensor element including an element body, a measurement pump cell being configured to pump out oxygen from surroundings of an inner measurement electrode to surroundings of an outer measurement electrode, and a measurement voltage detection sensor cell that detects a measurement voltage between a reference electrode and the inner measurement electrode, and a pump cell controller that executes a normal time measurement pump control process of pumping out oxygen in the measurement chamber during a normal operation time of the sensor element so that the measurement voltage reaches a normal time target value, and executes a start-up time measurement pump control process of pumping out oxygen in the measurement chamber at a start-up time of the sensor element earlier than the normal operation time so that the measurement voltage reaches a start-up time target value higher than the normal time target value.

Gas sensor

A gas sensor includes a sensor element and a pump cell controller. The pump cell controller performs a normal time control process after a heater control process is started, the normal time control process including a main pump control process, an auxiliary pump control process of controlling an auxiliary pump cell so that a voltage for auxiliary pump reaches a target value, and a normal time measurement pump control process of pumping out oxygen in a measurement chamber by controlling the measurement pump cell so that a measurement voltage reaches a normal time target value. In an early stage of the normal time control process, the pump cell controller performs a correction process of correcting the target value of the voltage for auxiliary pump to a value higher than a target value in a period after the early stage.

A gas sensor includes a sensor element and a pump cell controller. During a normal operation time of the sensor element, the pump cell controller executes a normal time measurement pump control process of pumping out the oxygen in a measurement chamber by controlling a measurement pump cell so that voltage for measurement reaches a normal time target value. At the start-up time of the sensor element, the pump cell controller executes a start-up time measurement pump control process of pumping out the oxygen in the measurement chamber by controlling the measurement pump cell so that the voltage for measurement reaches a start-up time target value higher than the normal time target value. When determining that the oxygen concentration in the measurement chamber is stabilized, the pump cell controller makes switching from the start-up time measurement pump control process to the normal time measurement pump control process.

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 gas sensor includes a sensor element including an element body, a first electrode, a second electrode, and a heater; a voltage acquisition section that acquires a voltage between the first electrode and the second electrode; a heater power supply; an external common lead that serves as both at least part of an electric circuit used to acquire the voltage by providing electrical continuity between the first electrode and the voltage acquisition section and at least part of an electric circuit used to supply an electric power from the heater power supply to the heater and that is disposed outside the sensor element; and a correction section that derives a value of a voltage drop in the external common lead in accordance with a heater current and that corrects the voltage acquired by the voltage acquisition section in accordance with the derived value of the voltage drop.

A gas sensor includes a main pump cell, a storage unit that stores information about a zero point in a first correspondence relationship, where the first correspondence relationship is a linear correspondence relationship between the oxygen concentration in a measurement-object gas and the main pump current, an oxygen-concentration-detecting unit that detects the oxygen concentration in a measurement-object gas, based on a measured value p of the main pump current and the information about the zero point, and a measured-value-obtaining unit that performs a second control process and that obtains a measured value bat a measurement point Bat which a known value of the oxygen concentration and the main pump current are relevant to each other with a measurement timing. The oxygen-concentration-detecting unit makes zero point correction such that a divergence of the zero point from the first correspondence relationship is corrected based on the measured value b

A sensor element used to detect, using a limiting current method, the specific gas concentration in a rich-atmosphere measurement-object gas. The sensor element includes a layered body in which a measurement-object gas distribution portion is provided, an adjustment pump cell that has an adjustment pump electrode arranged in an oxygen concentration adjustment space in the measurement-object gas distribution portion. The adjustment pump electrode contains Pt and Au, and a Au/Pt ratio (=the area of a portion where Au is exposed/the area of a portion where Pt is exposed) measured using X-ray photoelectron spectroscopy (XPS) is greater than or equal to 0.3 but not greater than 0.63.

Sensor element and gas sensor

A gas sensor detects the concentration of a specific gas on the basis of a pump current that flows when oxygen is pumped out from a measurement chamber, so that an oxygen concentration in the measurement chamber becomes a predetermined low concentration, the oxygen that is pumped out being oxygen that is generated when the specific gas is reduced in measurement chamber in a case where the specific gas is an oxide or being oxygen that is generated when a gas obtained as a result of conversion of the specific gas to an oxide is reduced in the measurement chamber in a case where the specific gas is a non-oxide. Further, the gas sensor corrects the pump current or the concentration of the specific gas on the basis of the oxygen concentration of the measurement-object gas when the measurement-object gas is in a rich atmosphere.

A gas sensor includes an element body, an inner main pump electrode, an inner auxiliary pump electrode, an inner preliminary pump electrode, a measurement electrode, a reference electrode, a measurement voltage detection device, a specific gas concentration detection device. The inner preliminary pump electrode, the inner main pump electrode, the inner auxiliary pump electrode and the measurement electrode include each contain a noble metal having catalytic activity. At least one of the inner preliminary pump electrode and the inner main pump electrode contains no noble metal having a catalytic activity suppression ability, the catalytic activity suppression ability being an ability to suppress the catalytic activity of the noble metal having the catalytic activity from being exhibited to the specific gas. The inner auxiliary pump electrode contains a noble metal having the catalytic activity suppression ability.

Gas sensor and sensor element

A catalyst deterioration diagnosis method is a method for a system. The system includes a stepped transmission or a continuously variable transmission connected to an internal combustion engine, a catalyst into which an exhaust gas from the internal combustion engine is introduced, and a gas sensor having sensitivity to ammonia that outputs a detection value corresponding to a component of an exhaust gas that has passed through the catalyst. The catalyst deterioration diagnosis method includes the following steps. Monitoring of temporary increase of a detection value of the gas sensor is started, and thereby a temporarily increased amount of the detection value of the gas sensor is acquired. The monitoring is started when upshifting of the stepped transmission or pseudo-upshifting of the continuously variable transmission is performed. Whether or not the temporarily increased amount is larger than a threshold amount is determined.

Catalyst deterioration diagnosis method and catalyst deterioration diagnosis system

In a gas sensor configured to measure the concentrations of a plurality of components in the presence of oxygen, in the interior of a structural body made from an oxygen ion conductive solid electrolyte, a preliminary chamber having a mixed potential electrode, an oxygen concentration adjustment chamber having a main pump electrode, and a measurement chamber having a measurement electrode are formed in a manner communicating in this order. While oxygen within the gas to be measured is being discharged by the main pump electrode and the measurement electrode, the NHconcentration within the gas to be measured is measured by a mixed potential Vof the mixed potential electrode.

Gas sensor and gas concentration measurement method

A gas sensor includes a structural body made up from a solid electrolyte that exhibits oxygen ion conductivity, a gas introduction port formed in the structural body, a preliminary chamber communicating with the gas introduction port and equipped with a preliminary pump electrode, a main chamber communicating with the preliminary chamber and equipped with a main pump electrode, and a measurement chamber communicating with the main chamber and equipped with a measurement electrode. In the gas sensor, at least a surface of the preliminary pump electrode is made of a material which exhibits a low activity with respect to a reaction between ammonia and oxygen.

Gas sensor and method of producing gas sensor

In a method of performing active control between a lean operation state and a rich operation state on a vehicle engine including a three way catalyst in an exhaust path, on a downstream side with respect to the three way catalyst in the exhaust path, a limited current type NOx sensor having NHinterference and also capable of detecting a change in an oxygen concentration on the downstream side is disposed, and an operation state of the vehicle engine is switched between a lean operation state and a rich operation state at a timing when a detection of a change in an oxygen concentration in an exhaust air flowing out from the three way catalyst or a detection of NOx or NHis performed first by the NOx sensor.

Operation control method of vehicle engine and vehicle system

A system of diagnosing a deterioration of a catalyst, which includes a precious metal component and a ceramic part and purifies an exhaust gas emitted from an engine, includes: a diagnosis means comparing a diagnosis object value corresponding to an output from an NOx sensor provided on a downstream side with respect to the catalyst and a predetermined diagnosis threshold value stored in a storage means, thereby diagnosing a degree of deterioration of the catalyst, wherein the diagnosis threshold value is previously determined based on a correlationship between the diagnosis object value and a total weight value of NOx and THC in the exhaust gas through the catalyst in a state where the vehicle travels under a constant threshold value setting condition, and the diagnosis means diagnoses that a deterioration occurs in the precious metal component when the diagnosis object value exceeds the diagnosis threshold value.

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Nagoya, Japan

Taku Okamoto