Ngk Insulators, Inc.

Akihiro Muroguchi

Nobukazu Ikoma

Takeya Miyashita

Kenshin Kitoh

San Jae Lee

A gas sensor for measuring NOx concentration in measurement gas based on sensor output depending on an amount of the detected oxygen includes an oxygen concentration control part for controlling oxygen concentration in the measurement gas. The oxygen concentration control part allows a control of oxygen concentration in the measurement gas to set at a designated value even after being mounted on an automobile, so that dependency of the sensor output with respect to oxygen concentration can be quantitatively detected. The sensor output for detecting NOx concentration is corrected by estimating an amount of a change accompanying the sensitivity degradation of the sensor output with respect to NOx concentration on the basis of a difference between oxygen output characteristics of the sensor output of an actually-used sensor and oxygen output characteristics of a sensor in the initial state, and correcting the sensor output in accordance with the amount of the change.

Gas sensor, control device thereof and method of measuring NOx concentration

A protective cover of a gas sensor includes an inner protective cover which covers at least an end portion of a sensor element, an outer protective cover which covers the inner protective cover, and an intermediate protective cover which is installed between the inner protective cover and the outer protective cover. A/A&#x2267;1 provided that Arepresents a total opening area of the inner gas inlet holes provided for the inner protective cover, and Arepresents a total opening area of the outer gas inlet holes provided for the outer protective cover.

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Nagoya, Japan

Akihiro Muroguchi