Ngk Insulators, Inc.

Ryo Hashikawa

Yusuke Watanabe

Taku Okamoto

Soichiro Yoshida

Takayuki Sekiya

Daichi Ichikawa

A sensor element includes: a plurality of internal spaces which sequentially communicate from a gas inlet, and in which respective inner electrodes are arranged; an outer electrode; a porous body region covering the outer electrode; and a plurality of electrochemical pump cells capable of pumping in or out oxygen between the internal spaces and an outside, and a ratio A/B is 0.07 or more, where A is a magnitude of a limiting current when a main pump cell including a main pump electrode in a first internal space located closest to the inlet and the outer pump electrode pumps in oxygen to the first internal space in a case where a pump in current evaluation gas is introduced, B is a magnitude of a limiting current when oxygen is pumped out from the first internal space in a case where a pump-out current evaluation gas is introduced.

Gas sensor

A gas sensor that detects a specific gas concentration in a measurement-object gas, the gas sensor includes: a sensor element having an element body provided with a measurement-object gas flow section therein, the measurement-object gas flow section introducing the measurement-object gas, a measurement electrode disposed in the measurement-object gas flow section, a measurement-object-gas side electrode provided on the element body, 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 measurement-object-gas side electrode and the reference electrode; and a controller that performs a moisture-concentration decrease process of controlling the reference-gas adjustment pump cell so that oxygen is pumped out from a periphery of the reference electrode to a periphery of the measurement-object-gas side electrode to decrease a moisture concentration around the reference electrode.

Gas sensor and method of controlling 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 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.

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 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.

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Nagoya, Japan

Ryo Hashikawa