In a sensor element 101, oxygen contained in a gas to be measured introduced into a first internal space 20 through a first diffusion control part 11 is pumped out by applying voltage between an inner pump electrode 22 and an outer pump electrode 23. After the oxygen is pumped out, NOx in the gas to be measured generates oxygen by being reduced by a measurement electrode 44. This oxygen is pumped by applying voltage between the measurement electrode 44 and the outer pump electrode 23. On the basis of current generated according to the amount of oxygen thus pumped, the NOx gas concentration is calculated. A slit width of the first diffusion control part 11 on an entrance side is larger than a slit width on an exit side.

Provided is a flat plate-type oxygen sensor element. The flat plate-type oxygen sensor element according to an exemplary embodiment of the present invention includes: a first electrolyte layer having a sensing electrode exposed to a target gas; a second electrolyte layer on which a reference electrode is disposed; and a heating unit having a heating resistor surrounded by an insulating layer and disposed between the sensing electrode and the reference electrode, wherein the heating unit is disposed so that the heating resistor is located at a position ranging from 40 to 60% of a total height from an upper surface of the first electrolyte layer to a lower surface of the second electrolyte layer.

Provided is a method of manufacturing a porous protective layer for a gas sensor. The porous protective layer according to one Example of the present invention is manufactured by a method of manufacturing a porous protective layer for a gas sensor including (1) a step of introducing a composition for forming a porous protective layer including a pore former and a ceramic powder, which includes particles having a degree of deformation of 1.5 or more expressed by the following Relational Formula 1 according to the present invention, onto a sensing electrode for a gas sensor, and (2) a step of sintering the introduced composition for forming a porous protective 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 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 control method of a gas sensor including a sensor element and an activity determining part includes a temperature raising step of heating the sensor element by a heater of the sensor element to raise a temperature of the sensor element up to an active temperature at which the activity determining part determines that the sensor element is in a measurable active state; a prior driving step of raising the temperature of the sensor element by the heater from the active temperature up to a steady driving temperature, and operating a main pump cell and a measurement pump cell of the sensor element to detect NOx in the measurement-object gas; and a steady driving step of maintaining the temperature of the sensor element by the heater at the steady driving temperature, and operating the main pump cell and the measurement pump cell to continuously detect NOx in the measurement-object gas.

An intake sensor includes a detection element, a heater, a housing, and a protector. The protector has two or more tubular portions spaced from one another in the radial direction. Of any two adjacent tubular portions, a second tubular portion on the outer side has tubular walls present in the penetration direction of first through holes of a first tubular portion on the inner side. Second through holes of the second tubular portion have an area equal to or greater than that of the first through hole. When the intake sensor is disposed in a model gas mixture of butane and air having air-fuel ratio of about 13, pressure of about 0.11 MPa, temperature of about 20° C., and flow rate of about 0 m/sec, and the heater heats the solid electrolyte member to the target temperature, no combustion flame is visually recognized on the outer surface of the protector.

A gas concentration detection apparatus is provided with a measuring gas chamber, a solid electrolyte body, a pump cell, a sensor cell, a pump cell controller and a sensor cell detection section. The pump cell controller applies an elimination voltage to the pump cell at a start-up point, before a gas concentration is detected. The water in the measuring gas chamber is decomposed and hydrogen is generated by application of the elimination voltage. Oxygen occluded in a sensor electrode of the sensor cell is removed by the hydrogen.

A gas sensor unit includes a gas sensor and a control unit. The gas sensor unit includes: a first oxygen pump cell having a pair of electrodes and controlling the oxygen concentration; a second oxygen pump cell controlling the oxygen concentration; and a sensor cell that detects the concentration of a specific gas component in a measurement target gas. The control unit is electrically connected to the gas sensor and sets a voltage between the pair of electrodes of the first oxygen pump cell to a predetermined set value, and performs energization control to control the introduction or discharge of oxygen while changing a voltage applied between a pair of electrodes of the second oxygen pump cell so that an oxygen pump current of the first oxygen pump cell is maintained within a predetermined range of IL≦I≦IH.

A heater unit includes a heater 72 having first bend portions 95 (95a to 95d) and second bend portions 96 (96a to 96f). The first bend portions 95 are turns present in a maximum-temperature area (first area 90a) where the maximum temperature is reached during heating among areas 88 where the turns have a narrower pitch and having apexes facing each other in the short-length direction (left-right direction) of a ceramic substrate. The second bend portions 96 are turns present in areas 89 where the turns have a wider pitch and having apexes facing each other in the short-length direction. The distance X1 [mm] between the first bend portions 95 facing each other is larger than the distance X2 [mm] between the second bend portions 96 facing each other.