The invention relates to a method for monitoring a NOx sensor (10) having an oxygen-ion-conducting solid electrolyte and having at least one cavity (12), wherein at least one cavity (12) of the NOx sensor is flooded with a defined oxygen concentration during a self-diagnosis of the NOx sensor. The gradient of a pump current resulting therefrom is evaluated and, in the case of a deviation in comparison with reference values, possibly impaired dynamics of the NOx sensor are inferred.

An abnormality detection device for an air-fuel ratio sensor is provided. An air-fuel ratio sensor is provided in an exhaust passage. A storage device stores mapping data specifying a mapping. The mapping outputs an abnormality determination variable using first time series data and second time series data as an input. The first time series data is time series data of an excess amount variable in a first predetermined period. The excess amount variable is a variable corresponding to an excess amount of fuel actually discharged to the exhaust passage in relation to an amount of fuel reacting without excess or deficiency with oxygen contained in a fluid discharged to the exhaust passage. The second time series data is time series data of an air-fuel ratio detection variable in a second predetermined period.

A method for monitoring a gas sensor (14) which comprises two electrochemical measuring cells (20, 30) and which is arranged in an exhaust tract (10) of an internal combustion engine (11), wherein the sensor elements (20, 30) exhibit a substantially identical sensitivity towards a first gas component and a different sensitivity towards a second gas component and are insensitive towards further gas components. In an operating state in which an exhaust gas stream at the gas sensor (14) contains less of the second gas component than of the first gas component a concentration of the first gas component is calculated from each of the sensor signals from the sensor elements (20, 30) and a defect in a sensor element (20, 30) is deduced from the concentrations of the first gas component.

A honeycomb body having a porous ceramic honeycomb structure with a first end, a second end, and a plurality of walls having wall surfaces defining a plurality of inner channels. A highly porous layer is disposed on one or more of the wall surfaces of the honeycomb body. The highly porous layer has a porosity greater than 90%, and has an average thickness of greater than or equal to 0.5 m and less than or equal to 10 m. A method of making a honeycomb body includes depositing a layer precursor on a ceramic honeycomb body and binding the layer precursor to the ceramic honeycomb body to form the highly porous layer.

An abnormality detection device determines abnormality in an exhaust gas sensor, disposed in an exhaust passage of an engine to detect a component in exhaust gas. The abnormality detection device includes: a responsiveness determination unit configured to calculate responsiveness of the exhaust gas sensor on the basis of a timewise change of output values of the exhaust gas sensor; and an abnormality determination unit configured to determine that the exhaust gas sensor has abnormality when the responsiveness calculated by the responsiveness determination unit is lower than a predetermined responsiveness threshold. The abnormality determination unit determines if the exhaust gas sensor has abnormality, excluding an excluded period during which a slope of the output values becomes zero or is inversed with respect to a preceding trend of the timewise change while the output values of the exhaust gas sensor timewisely change between a predetermined first and second determination values.

An abnormality detection device for an air-fuel ratio sensor is provided. An air-fuel ratio sensor is provided in an exhaust passage. A storage device stores mapping data specifying a mapping. The mapping outputs an abnormality determination variable using first time series data and second time series data as an input. The first time series data is time series data of an excess amount variable in a first predetermined period. The excess amount variable is a variable corresponding to an excess amount of fuel actually discharged to the exhaust passage in relation to an amount of fuel reacting without excess or deficiency with oxygen contained in a fluid discharged to the exhaust passage. The second time series data is time series data of an air-fuel ratio detection variable in a second predetermined period.

An exhaust gas sensor is diagnosed with high accuracy as much as possible while maintaining the function of an exhaust system of an internal combustion engine. In a diagnostic apparatus for an exhaust gas sensor which is applied to an internal combustion engine including an exhaust gas sensor, a fuel supplier, a controller configured to carry out predetermined fuel supply processing and predetermined oxygen concentration processing, and which diagnoses the exhaust gas sensor based on an output value thereof, provision is made for the controller that sets as a diagnostic output value a first output value, which is an output value at the side of the highest oxygen concentration in the output value of the exhaust gas sensor in a measurement period, and performs the diagnosis of the exhaust gas sensor based on the diagnostic output value, when predetermined fuel supply processing is carried out in the measurement period.

The present invention relates to an exhaust gas sensor arrangement structure comprising: an exhaust pipe 6 extending from an engine 3 to form a part of an exhaust flow path; an exhaust valve 7 that adjusts an aperture of the exhaust flow path; and a first exhaust gas sensor 8a that detects a predetermined component in an exhaust gas flowing through the exhaust flow path. The first exhaust gas sensor has a detector 80 arranged to protrude into the exhaust flow path. The exhaust valve includes a plate-like valve body 70 that expands and reduces a flow path cross section of the exhaust flow path, and a rotating shaft 71 extending in a direction intersecting with an axial direction of the exhaust flow path and serving as a rotation center of the valve body. A downstream end of the valve body approaches the detector as the valve body is rotated in a direction of reducing the flow path cross section.

A honeycomb body having a porous ceramic honeycomb structure with a first end, a second end, and a plurality of walls having wall surfaces defining a plurality of inner channels. A highly porous layer is disposed on one or more of the wall surfaces of the honeycomb body. The highly porous layer has a porosity greater than 90%, and has an average thickness of greater than or equal to 0.5 m and less than or equal to 10 m. A method of making a honeycomb body includes depositing a layer precursor on a ceramic honeycomb body and binding the layer precursor to the ceramic honeycomb body to form the highly porous layer.

A control apparatus is provided for controlling an exhaust gas sensor. The exhaust gas sensor includes a first cell, a second cell configured to output electric current depending on the concentration of a measurement target component in exhaust gas from which oxygen has been removed by the first cell, and a heater configured to heat the first and second cells. The control apparatus includes a heater controlling unit, a current detecting unit configured to detect the electric current outputted from the second cell, and a deterioration determining unit. The deterioration determining unit causes the heater controlling unit to change output of the heater and thereby changes the temperature of the first cell. During the change in the output of the heater, the deterioration determining unit determines, based on an amount of change in the electric current detected by the current detecting unit, whether or not the second cell is deteriorated.