The gas sensor is equipped with a sensor device, a plurality of electrode springs contacting with electrodes and of the sensor device, an insulator retaining the electrode springs, and a plurality of leads connected to the respective electrode springs. Each of the electrode springs includes a retained portion retained by the insulator and a contact portion which is bent and inclined from the retained portion toward a front end side of the sensor device in the lengthwise direction. The contact portion is elastically deformed in contact with the electrode. Each of the electrode springs also includes a bent portion between the contact portion and the retained portion. The bent portion constitutes a base end of the contact portion and is oriented toward the base end side of the gas sensor in the lengthwise direction, thereby enabling the length of the sensor device to be decreased and improving the heat resistance of the electrode springs.

The gas sensor is equipped with a sensor device, a plurality of electrode springs contacting with electrodes and of the sensor device, an insulator retaining the electrode springs, and a plurality of leads connected to the respective electrode springs. Each of the electrode springs includes a retained portion retained by the insulator and a contact portion which is bent and inclined from the retained portion toward a front end side of the sensor device in the lengthwise direction. The contact portion is elastically deformed in contact with the electrode. Each of the electrode springs also includes a bent portion between the contact portion and the retained portion. The bent portion constitutes a base end of the contact portion and is oriented toward the base end side of the gas sensor in the lengthwise direction, thereby enabling the length of the sensor device to be decreased and improving the heat resistance of the electrode springs.

A method for producing a gas sensor element, for covering a detection portion (150) by an inner protection layer (21) and an outer protection layer (22), including: a first dipping step of dipping the gas sensor element into a first slurry S1 for the inner protection layer, to form a first coating film (700) on a front end surface (100c) and a peripheral surface (100d); a drying step of drying and solidifying the first coating film; a second dipping step of dipping, without removing the first coating film, the gas sensor element into a second slurry S2 for the outer protection layer, to form a second coating film (800) on a surface of the solidified first coating film; and a scraping-off step of performing scraping-off on the second coating film so as not to scrape-off the first coating film, to remove a part of the second coating film.

A method for producing a gas sensor element, for covering a detection portion (150) by an inner protection layer (21) and an outer protection layer (22), including: a first dipping step of dipping the gas sensor element into a first slurry S1 for the inner protection layer, to form a first coating film (700) on a front end surface (100c) and a peripheral surface (100d); a drying step of drying and solidifying the first coating film; a second dipping step of dipping, without removing the first coating film, the gas sensor element into a second slurry S2 for the outer protection layer, to form a second coating film (800) on a surface of the solidified first coating film; and a scraping-off step of performing scraping-off on the second coating film so as not to scrape-off the first coating film, to remove a part of the second coating film.

A method for manufacturing a sensor element for detecting (i) a gas component in a measuring gas or (ii) a temperature of the measuring gas includes: introducing at least one functional element into at least one slip at least once in such a way that a slip layer is applied to the functional element, the functional element including at least one solid electrolyte and at least one functional layer; sintering the slip layer on the functional element; grinding the slip layer at least in the area of the at least one functional layer; impregnating the slip layer; and thermally treating the impregnated slip layer.

A method for manufacturing a sensor element for detecting (i) a gas component in a measuring gas or (ii) a temperature of the measuring gas includes: introducing at least one functional element into at least one slip at least once in such a way that a slip layer is applied to the functional element, the functional element including at least one solid electrolyte and at least one functional layer; sintering the slip layer on the functional element; grinding the slip layer at least in the area of the at least one functional layer; impregnating the slip layer; and thermally treating the impregnated slip layer.

A multi-gas detection apparatus is configured such that electric power supplied from a power supply to a heater is controlled by pulse width modulation so as to control the temperature of a first solid electrolyte body. The multi-gas detection apparatus detects the concentration of ammonia by using a first ammonia detection section in which an electromotive force is generated between a first reference electrode and a first detection electrode in accordance with the concentration of ammonia in the exhaust gas. The multi-gas detection apparatus calculates the amount of a change (i.e., offset voltage) in the ammonia electromotive force caused by change in the output voltage of the power supply. The multi-gas detection apparatus corrects the ammonia electromotive force generated in the first ammonia detection section through use of the calculated change amount.

A multi-gas detection apparatus is configured such that electric power supplied from a power supply to a heater is controlled by pulse width modulation so as to control the temperature of a first solid electrolyte body. The multi-gas detection apparatus detects the concentration of ammonia by using a first ammonia detection section in which an electromotive force is generated between a first reference electrode and a first detection electrode in accordance with the concentration of ammonia in the exhaust gas. The multi-gas detection apparatus calculates the amount of a change (i.e., offset voltage) in the ammonia electromotive force caused by change in the output voltage of the power supply. The multi-gas detection apparatus corrects the ammonia electromotive force generated in the first ammonia detection section through use of the calculated change amount.

A gas sensor according to the present invention includes a sensor element made of a solid electrolyte and having at least a cylindrical portion arranged coaxially with an axis of the sensor element and a front end portion closing a front end of the cylindrical portion and a heater formed into either a cylindrical shape or a cylindrical column shape and located inside the sensor element to heat the sensor element by heat generation thereof, wherein a front end portion of the heater is in contact with an inner surface of the front end portion of the sensor element; and wherein a lateral portion of the heater is in contact with an inner circumferential surface of the cylindrical portion of the sensor element.

A gas sensor according to the present invention includes a sensor element made of a solid electrolyte and having at least a cylindrical portion arranged coaxially with an axis of the sensor element and a front end portion closing a front end of the cylindrical portion and a heater formed into either a cylindrical shape or a cylindrical column shape and located inside the sensor element to heat the sensor element by heat generation thereof, wherein a front end portion of the heater is in contact with an inner surface of the front end portion of the sensor element; and wherein a lateral portion of the heater is in contact with an inner circumferential surface of the cylindrical portion of the sensor element.