Abstract: A multi-gas sensor controller 9 is provided in an urea SCR system 1 with an SCR catalyst 4, an aqueous urea injector 5 and a multi-gas sensor 8 (ammonia sensor unit and NOx sensor unit). The multi-gas sensor controller 9 determines the concentration of ammonia in exhaust gas flowing out of the SCR catalyst 4, as a downstream ammonia concentration value, based on a detection result of the ammonia detection unit. The multi-gas sensor controller 9 controls the aqueous urea injector 5 to supply urea to the SCR catalyst 4 in a fuel-cut state. Further, the multi-gas sensor controller 9 correct the determined downstream ammonia concentration value based on a detection result of the NOx detection unit and an oxygen concentration of the exhaust gas after the supply of urea to the SCR catalyst with the control of the aqueous urea injector 5 by the controller 9.

Abstract: In a multi-gas sensor control apparatus 1, the concentrations of ammonia, NO2, and NO contained in a gas under measurement are computed as a result of execution of gas concentration computation processing by a CPU 61 of a microcomputer 60. In the gas concentration computation processing, depending on whether or not a correction permission condition is satisfied (S200), the CPU 61 switches its operation between an operation of storing the latest corrected ammonia concentration as a value of “NH3 concentration (this time)” (S170) and an operation of storing a value of “NH3 concentration (reference)” as a value of “NH3 concentration (this time)” (S210). The multi-gas sensor control apparatus 1 can suppress a decrease in the accuracy of detection of the ammonia concentration performed through use of a multi-gas sensor 2.

Abstract: A deterioration diagnosis device for an oxidation catalyst includes: a multi-gas sensor disposed in an exhaust passage downstream of an oxidation catalyst, the multi-gas sensor including a NO2 sensor unit and a NOX sensor unit, the NO2 sensor unit directly detecting a NO2 concentration in exhaust gas after passing through the oxidation catalyst, and the NOX sensor unit directly detecting a NOX concentration in the exhaust gas; an NO concentration calculation unit configured to calculate an NO concentration in the exhaust gas after passing through the oxidation catalyst based on the NO2 concentration and the NOX concentration; and a deterioration judgment unit configured to determine a deterioration degree of the oxidation catalyst from an evaluation value based on the NO concentration calculated by the NO concentration calculation unit.

Abstract: A multigas sensor (200A) includes a multigas sensor element portion (100A) having: a NOx sensor portion (30A) which detects the concentration of NOx; and first and second ammonia sensor portions (42x, 42y) having different ratios between a sensitivity of ammonia and a sensitivity of NOx. The multigas sensor element portion has a plate-like shape which extends in the direction of the axis O. A temperature detecting portion (6) used for controlling the temperature of the NOx sensor portion is disposed in the multigas sensor element portion. The first and second ammonia sensor portions are disposed on the outer surface of the NOx sensor portion so that at least parts of the first and second ammonia sensor portions overlap with a first region (6s) which is defined in the width direction by ends in the axial direction of the temperature detecting portion.

Abstract: A deterioration diagnosis device for an oxidation catalyst includes: a multi-gas sensor disposed in an exhaust passage downstream of an oxidation catalyst, the multi-gas sensor including a NO2 sensor unit and a NOX sensor unit, the NO2 sensor unit directly detecting a NO2 concentration in exhaust gas after passing through the oxidation catalyst, and the NOX sensor unit directly detecting a NOX concentration in the exhaust gas; an NO concentration calculation unit configured to calculate an NO concentration in the exhaust gas after passing through the oxidation catalyst based on the NO2 concentration and the NOX concentration; and a deterioration judgment unit configured to determine a deterioration degree of the oxidation catalyst from an evaluation value based on the NO concentration calculated by the NO concentration calculation unit.

Abstract: A deterioration diagnosis device for an oxidation catalyst includes: a multi-gas sensor disposed in an exhaust passage downstream of an oxidation catalyst, the multi-gas sensor including a NO2 sensor unit and a NOX sensor unit, the NO2 sensor unit directly detecting a NO2 concentration in exhaust gas after passing through the oxidation catalyst, and the NOX sensor unit directly detecting a NOX concentration in the exhaust gas; an NO concentration calculation unit configured to calculate an NO concentration in the exhaust gas after passing through the oxidation catalyst based on the NO2 concentration and the NOX concentration; and a deterioration judgment unit configured to determine a deterioration degree of the oxidation catalyst from an evaluation value based on the NO concentration calculated by the NO concentration calculation unit.

Abstract: A multi-gas sensor controller 9 is provided in an urea SCR system 1 with an SCR catalyst 4, an aqueous urea injector 5 and a multi-gas sensor 8 (ammonia sensor unit and NOx sensor unit). The multi-gas sensor controller 9 determines the concentration of ammonia in exhaust gas flowing out of the SCR catalyst 4, as a downstream ammonia concentration value, based on a detection result o the ammonia detection unit. The multi-gas sensor controller 9 controls the aqueous urea injector 5 to supply urea to the SCR catalyst 4 in a fuel-cut state. Further, the multi-gas sensor controller 9 correct the determined downstream ammonia concentration value based on a detection result of the NOx detection unit and an oxygen concentration of the exhaust gas after the supply of urea to the SCR catalyst with the control of the aqueous urea injector 5 by the controller 9.

Abstract: In a multi-gas sensor control apparatus 1, the concentrations of ammonia, NO2, and NO contained in a gas under measurement are computed as a result of execution of gas concentration computation processing by a CPU 61 of a microcomputer 60. In the gas concentration computation processing, depending on whether or not a correction permission condition is satisfied (S200), the CPU 61 switches its operation between an operation of storing the latest corrected ammonia concentration as a value of “NH3 concentration (this time)” (S170) and an operation of storing a value of “NH3 concentration (reference)” as a value of “NH3 concentration (this time)” (S210). The multi-gas sensor control apparatus 1 can suppress a decrease in the accuracy of detection of the ammonia concentration performed through use of a multi-gas sensor 2.

Abstract: A multigas sensor (200A) includes a multigas sensor element portion (100A) having: a NOx sensor portion (30A) which detects the concentration of NOx; and first and second ammonia sensor portions (42x, 42y) having different ratios between a sensitivity of ammonia and a sensitivity of NOx. The multigas sensor element portion has a plate-like shape which extends in the direction of the axis O. A temperature detecting portion (6) used for controlling the temperature of the NOx sensor portion is disposed in the multigas sensor element portion. The first and second ammonia sensor portions are disposed on the outer surface of the NOx sensor portion so that at least parts of the first and second ammonia sensor portions overlap with a first region (6s) which is defined in the width direction by ends in the axial direction of the temperature detecting portion.

Abstract: A deterioration diagnosis device for an oxidation catalyst includes: a multi-gas sensor disposed in an exhaust passage downstream of an oxidation catalyst, the multi-gas sensor including a NO2 sensor unit and a NOX sensor unit, the NO2 sensor unit directly detecting a NO2 concentration in exhaust gas after passing through the oxidation catalyst, and the NOX sensor unit directly detecting a NOX concentration in the exhaust gas; an NO concentration calculation unit configured to calculate an NO concentration in the exhaust gas after passing through the oxidation catalyst based on the NO2 concentration and the NOX concentration; and a deterioration judgment unit configured to determine a deterioration degree of the oxidation catalyst from an evaluation value based on the NO concentration calculated by the NO concentration calculation unit.

Abstract: An ammonium gas sensor is provided. The ammonium gas sensor includes: a solid electrolyte layer having oxygen ion conductivity; a detection electrode formed on one surface of the solid electrolyte layer; a reference electrode that is a counter electrode of the detection electrode; a selective reaction layer covering the detection electrode; and a protection layer covering the selective reaction layer and made from a porous material; wherein the detection electrode includes a noble metal as a main component; the selective reaction layer includes oxide represented by AxMyOz as a main component, where A is one or more kind(s) of metal, M is vanadium, tungsten, or molybdenum and x, y, z are atomic ratios; and the protection layer includes the oxide that is in an amount smaller than a content of the oxide included in the selective reaction layer.

Abstract: An ammonium gas sensor is provided. The ammonium gas sensor includes: a solid electrolyte layer having oxygen ion conductivity; a detection electrode formed on one surface of the solid electrolyte layer; a reference electrode that is a counter electrode of the detection electrode; a selective reaction layer covering the detection electrode; and a protection layer covering the selective reaction layer and made from a porous material; wherein the detection electrode includes a noble metal as a main component; the selective reaction layer includes oxide represented by AxMyOz as a main component, where A is one or more kind(s) of metal, M is vanadium, tungsten, or molybdenum and x, y, z are atomic ratios; and the protection layer includes the oxide that is in an amount smaller than a content of the oxide included in the selective reaction layer.

Abstract: An ammonia gas sensor (200A) having an oxygen ion conductive solid electrolyte member (22A); a detection electrode (2A) and a reference electrode (4A) which are disposed on the solid electrolyte member; and an intermediate layer (5A) interposing between the detection electrode and the solid electrolyte member; wherein the intermediate layer contains the oxygen ion conductive solid electrolyte component in an amount of 50 wt % or more, and a first metal oxide which is an oxide of at least one metal selected from the group consisting of Co, Mn, Cu, Ni, and Ce, and the detection electrode contains Au in an amount of 70 wt % or higher and no first metal oxide.

Abstract: A method and apparatus for controlling a multi-gas sensor, including an NOX sensor section and an ammonia sensor section. The NOX sensor section includes a first pumping cell adapted to pump oxygen into or out of a gas under measurement introduced into a first measurement chamber, and a second pumping cell communicating with the first measurement chamber and configured such that a second pumping current Ip2 corresponds to an NOX concentration of the gas under measurement. Oxygen concentration is calculated on the basis of a first pumping current flowing through the first pumping cell, and a corrected ammonia concentration is calculated on the basis of the oxygen concentration and the ammonia concentration output of the ammonia sensor section.

Abstract: A multigas sensor (200A) including a gas sensor element (100A) extending in an axial direction (O) and having an NOx sensor portion (30) and an ammonia sensor portion (42); a metallic shell (138); and a closed-bottomed tubular protector (141) having gas introduction holes (143a) formed in its side wall (143d), and a gas discharge hole (143b) formed in its front end wall (143t). At least a subportion of the ammonia sensor portion (42) is disposed within a positional range along the axial direction (O) between the gas introduction holes (143a) and the gas discharge hole (143b). The shortest distance (d1) between the gas introduction hole (143a) and the ammonia sensor portion (42) is shorter than the shortest distance (d2) between the gas introduction hole (143a) and the gas diffusion hole (8a).

Abstract: An ammonia gas sensor including a reference electrode (320) is formed on the back surface of a solid electrolyte member (310), and a detection electrode (335) is formed on the front surface of the solid electrolyte member (310). A detection lead (350) is provided on the front surface of the solid electrolyte member (310) such that the detection lead (350) is connected to the detection electrode (335). An insulating layer (340), (380) is provided between the detection lead (350) and the solid electrolyte member (310), or on the detection lead (350).

Abstract: A method and apparatus for controlling a multi-gas sensor, including an NOX sensor section and an ammonia sensor section. The NOX sensor section includes a first pumping cell adapted to pump oxygen into or out of a gas under measurement introduced into a first measurement chamber, and a second pumping cell communicating with the first measurement chamber and configured such that a second pumping current Ip2 corresponds to an NOX concentration of the gas under measurement. Oxygen concentration is calculated on the basis of a first pumping current flowing through the first pumping cell, and a corrected ammonia concentration is calculated on the basis of the oxygen concentration and the ammonia concentration output of the ammonia sensor section.

Abstract: An ammonium gas sensor is provided. The ammonium gas sensor includes: a solid electrolyte layer having oxygen ion conductivity; a detection electrode formed on one surface of the solid electrolyte layer; a reference electrode that is a counter electrode of the detection electrode; a selective reaction layer covering the detection electrode; and a protection layer covering the selective reaction layer and made from a porous material; wherein the detection electrode includes a noble metal as a main component; the selective reaction layer includes oxide represented by AxMyOz as a main component, where A is one or more kind(s) of metal, M is vanadium, tungsten, or molybdenum and x, y, z are atomic ratios; and the protection layer includes the oxide that is in an amount smaller than a content of the oxide included in the selective reaction layer.

Abstract: An ammonia gas sensor including a reference electrode (320) is formed on the back surface of a solid electrolyte member (310), and a detection electrode (335) is formed on the front surface of the solid electrolyte member (310). A detection lead (350) is provided on the front surface of the solid electrolyte member (310) such that the detection lead (350) is connected to the detection electrode (335). An insulating layer (340), (380) is provided between the detection lead (350) and the solid electrolyte member (310), or on the detection lead (350).

Abstract: An ammonia gas sensor which includes a solid electrolyte member (310) extending in an axial direction; a reference electrode (320) provided on the solid electrolyte member (310); and a detection electrode (331) and a selective reaction layer (340) provided on the solid electrolyte member (310). The detection electrode serves as a counterpart of the reference electrode (320). The detection electrode (331) contains a noble metal as a predominant component, and the selective reaction layer (340) contains a metal oxide as a predominant component.