Abstract: An exhaust gas purification apparatus for an internal combustion engine includes a filter supporting the catalyst with an oxygen storage capacity, an air fuel ratio sensor to detect an air fuel ratio of exhaust gas at the downstream side of the filter, and a controller configured to change an air fuel ratio of exhaust gas flowing into the filter, to estimate an amount of particulate matter deposited in an interior of a partition wall of the filter, estimate a maximum storable oxygen amount of the catalyst from a change of the air fuel ratio of exhaust gas obtained by the air fuel ratio sensor at the time when the air fuel ratio of exhaust gas is changed by the controller, and correct the maximum storable oxygen amount of the catalyst based on the amount of particulate matter deposited in the interior of the partition wall of the filter.

Abstract: An abnormality diagnosis system of an air-fuel ratio sensor acquires a blowby gas flow ratio showing a ratio of the flow of blowby gas to the flow of gas to a combustion chamber and an output current of an air-fuel ratio sensor during fuel cut control in which an internal combustion engine stops the feed of fuel to the combustion chamber and at a plurality of points of time of different flows of blowby gas passing through a blowby gas passage and flowing to the downstream side of a throttle valve in the intake passage, calculate an output current of the air-fuel ratio sensor corresponding to a blowby gas flow ratio smaller than the blowby gas flow ratios acquired at the plurality of points of time, based on the acquired blowby gas flow ratio and output current, and judge the air-fuel ratio sensor for abnormality based on the calculated output current.

Abstract: 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.

Abstract: An internal combustion engine comprises an exhaust purification catalyst and an air-fuel ratio sensor arranged at a downstream side of the exhaust purification catalyst, stops or decreases a feed of fuel as fuel cut control, and controls an air-fuel ratio of exhaust gas to a rich air-fuel ratio after the end of the fuel cut control as post reset rich control. The diagnosis system calculates a first characteristic of change of air-fuel ratio at the time when the output air-fuel ratio first passes a first air-fuel ratio region leaner than a stoichiometric air-fuel ratio and a second characteristic of change of air-fuel ratio at the time when the output air-fuel ratio first passes a second air-fuel ratio region including a stoichiometric air-fuel ratio. The diagnosis system diagnoses the abnormality of the air-fuel ratio sensor based on the first characteristic of change of air-fuel ratio and the second characteristic of change of air-fuel ratio.

Abstract: An object is to prevent a wrong diagnosis from being made in diagnosis of an NOx sensor provided downstream of an SCR catalyst. A diagnosis apparatus is applied to an NOx sensor provided in an exhaust system including an SCR catalyst, a reducing agent supply device, an NOx sensor, an exhaust gas purification device provided upstream of the SCR catalyst, and a controller configured to raise the temperature of the exhaust gas purification device and control supply of reducing agent so as to adjust the ammonia adsorption amount to a specific amount. The controller is further configured to perform diagnosis of the NOx sensor on the basis of the concentration of ammonia slipping out of the SCR catalyst and disallow diagnosis of the NOx sensor since the ammonia adsorption amount is adjusted to the specific amount until a specific time elapses.

Abstract: An exhaust gas purification apparatus for an internal combustion engine includes a filter supporting the catalyst with an oxygen storage capacity, an air fuel ratio sensor to detect an air fuel ratio of exhaust gas at the downstream side of the filter, and a controller configured to change an air fuel ratio of exhaust gas flowing into the filter, to estimate an amount of particulate matter deposited in an interior of a partition wall of the filter, estimate a maximum storable oxygen amount of the catalyst from a change of the air fuel ratio of exhaust gas obtained by the air fuel ratio sensor at the time when the air fuel ratio of exhaust gas is changed by the controller, and correct the maximum storable oxygen amount of the catalyst based on the amount of particulate matter deposited in the interior of the partition wall of the filter.

Abstract: The abnormality diagnosis system of an air-fuel ratio sensor comprising an exhaust purification catalyst, an upstream side air-fuel ratio sensor provided at an upstream side of the exhaust purification catalyst, a downstream air-fuel ratio sensor provided at a downstream side of the exhaust purification catalyst, and a diagnosis device diagnosing the downstream air-fuel ratio sensor for abnormality based on outputs of these air-fuel ratio sensors. The diagnosis device judges that the downstream air-fuel ratio sensor suffers from an abnormality if the output air-fuel ratio of the upstream side air-fuel ratio sensor has become a rich air-fuel ratio richer than a stoichiometric air-fuel ratio, and the output air-fuel ratio of the downstream air-fuel ratio sensor air-fuel ratio has changed from an air-fuel ratio richer than a lean judged reference air-fuel ratio to an air-fuel ratio leaner than the lead judged reference air-fuel ratio.

Abstract: An oil dilution rate calculation system of an internal combustion engine acquires a blowby gas flow ratio showing the ratio of the flow of blowby gas to the flow of gas to the combustion chamber and an output current of the air-fuel ratio sensor during fuel cut control in which the internal combustion engine stops the feed of fuel to the combustion chamber and at a plurality of points of time of different flows of blowby gas passing through the blowby gas passage and flowing to the downstream side of the throttle valve in the intake passage, and calculate an oil dilution rate based on the acquired blowby gas flow ratio and output current.

Abstract: An abnormality diagnosis system of an air-fuel ratio sensor is provided with an exhaust purification catalyst, an upstream side air-fuel ratio sensor which is provided at an upstream side of the exhaust purification catalyst, a downstream side air-fuel ratio sensor which is provided at a downstream side of the exhaust purification catalyst, and a diagnosis device which uses the outputs of these air-fuel ratio sensors as the basis to diagnose abnormality of the downstream side air-fuel ratio sensor.

Abstract: The present invention provides a deterioration diagnosis apparatus for an exhaust gas purification apparatus, including a first sensor that measures the oxygen concentration of the exhaust gas flowing into the exhaust gas purification apparatus, a second sensor that measures the oxygen concentration of the exhaust gas flowing out of the exhaust gas purification apparatus, and diagnosing means for diagnosing deterioration of the exhaust gas purification apparatus on the basis of a difference that appears between a measurement value of the first sensor and a measurement value of the second sensor when the air-fuel ratio of the exhaust gas flowing into the exhaust pas purification apparatus is switched from a lean air-fuel ratio to a rich air-fuel ratio, wherein, when the air-fuel ratio of the exhaust gas is switched from a lean air-fuel ratio to a rich air-fuel ratio, a water-gas shift reaction is generated upstream of the first sensor.

Abstract: An oil dilution rate calculation system of an internal combustion engine acquires a blowby gas flow ratio showing the ratio of the flow of blowby gas to the flow of gas to the combustion chamber and an output current of the air-fuel ratio sensor during fuel cut control in which the internal combustion engine stops the feed of fuel to the combustion chamber and at a plurality of points of time of different flows of blowby gas passing through the blowby gas passage and flowing to the downstream side of the throttle valve in the intake passage, and calculate an oil dilution rate based on the acquired blowby gas flow ratio and output current.

Abstract: 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.

Abstract: An apparatus according to the present invention is adapted to calculate an NOX storage rate defined as the rate of the quantity of NOX stored into the NSR catalyst to the quantity of NOX flowing into the NSR catalyst, based on quantity of NOX flowing into the NSR catalyst and the quantity of NOX flowing out of the NSR catalyst in a state in which the amount of NOX stored in the NSR catalyst is equal to or larger than the breakthrough start amount of a criterion catalyst and the flow rate of exhaust gas flowing through the NSR catalyst is equal to or higher than a predetermined lower limit flow rate. The apparatus diagnoses the NSR catalyst as normal if the NOX storage rate thus calculated is equal to or higher than a predetermined threshold and as abnormal if the NOX storage rate is lower than the predetermined threshold.

Abstract: An internal combustion engine comprises an exhaust purification catalyst arranged in an exhaust passage of the internal combustion engine; an upstream side air-fuel ratio sensor for detecting an air-fuel ratio of exhaust gas flowing into the exhaust purification catalyst; and a downstream side air-fuel ratio sensor for detecting an air-fuel ratio of exhaust gas flowing out from the exhaust purification catalyst. An abnormality diagnosis system of air-fuel ratio sensors judges that at least one of the air-fuel ratio sensors has become abnormal when a difference or ratio between an output value of said upstream side air-fuel ratio sensor and an output value of said downstream side air-fuel ratio sensor becomes outside a predetermined range of normal difference or predetermined range of normal ratio during atmospheric gas introduction control where the exhaust gas flowing into the exhaust purification catalyst becomes atmospheric gas.

Abstract: A deterioration diagnosis apparatus for an exhaust gas purification apparatus according to the invention performs an induction process when an internal combustion engine is operating at a lean air-fuel ratio, measures the air-fuel ratio of the exhaust gas flowing into the SCR catalyst and the air-fuel ratio of the exhaust gas flowing out of the SCR catalyst by the air-fuel ratio sensor during the period through which the induction process is performed, and diagnoses deterioration of the SCR catalyst based on the difference between the air-fuel ratios thus measured. The diagnosis apparatus adjusts the quantity of reducing agent supplied to a hydrogen production catalyst during the period through which the induction process is performed, taking account of the degree of deterioration of the hydrogen production catalyst.

Abstract: A deterioration diagnosis apparatus for an exhaust gas purification apparatus according to the invention performs an induction process when an internal combustion engine is operating at a lean air-fuel ratio, measures the air-fuel ratio of the exhaust gas flowing into the SCR catalyst and the air-fuel ratio of the exhaust gas flowing out of the SCR catalyst by the air-fuel ratio sensor during the period through which the induction process is performed, and diagnoses deterioration of the SCR catalyst based on the difference between the air-fuel ratios thus measured. The diagnosis apparatus adjusts the quantity of reducing agent supplied to a hydrogen production catalyst during the period through which the induction process is performed, taking account of the degree of deterioration of the hydrogen production catalyst.

Abstract: An object is to prevent a wrong diagnosis from being made in diagnosis of an NOx sensor provided downstream of an SCR catalyst. A diagnosis apparatus is applied to an NOx sensor provided in an exhaust system including an SCR catalyst, a reducing agent supply device, an NOx sensor, an exhaust gas purification device provided upstream of the SCR catalyst, and a controller configured to raise the temperature of the exhaust gas purification device and control supply of reducing agent so as to adjust the ammonia adsorption amount to a specific amount. The controller is further configured to perform diagnosis of the NOx sensor on the basis of the concentration of ammonia slipping out of the SCR catalyst and disallow diagnosis of the NOx sensor since the ammonia adsorption amount is adjusted to the specific amount until a specific time elapses.

Abstract: In a deterioration diagnosis apparatus for a selective catalytic reduction (SCR) catalyst in which when an air fuel ratio of a mixture to be combusted in an internal combustion engine is a lean air fuel ratio, inducement processing is executed which is to induce a water gas shift reaction in a pre-stage catalyst, by changing the air fuel ratio of the mixture from the lean air fuel ratio to a predetermined rich air fuel ratio, and diagnosis processing is executed which is to diagnose deterioration of the SCR catalyst based on an output difference between two air fuel ratio sensors at the time of the execution of the inducement processing, when the SCR catalyst is in a state of being subjected to sulfur poisoning resulting from the execution of the S purge processing of the pre-stage catalyst, diagnosis processing is not executed.

Abstract: Deterioration of a selective catalytic reduction (SCR) catalyst can be diagnosed with sufficient accuracy, by making use of a sensor for measuring an air fuel ratio of exhaust gas flowing into an exhaust gas purification apparatus, which is equipped with the SCR catalyst, and a sensor for measuring an air fuel ratio of exhaust gas flowing out from the exhaust gas purification apparatus.

Abstract: The internal combustion engine comprises an exhaust purification catalyst 20, a downstream side sensor 41, an air-fuel ratio control unit, and an oxygen storage amount calculating unit for calculating the oxygen excess/deficiency of the inflowing exhaust gas in an air-fuel ratio maintenance time period and cumulatively adding the calculated oxygen excess/deficiency to calculate a maximum oxygen storage amount of the exhaust purification catalyst. The oxygen storage amount calculating unit uses a point of time that an absolute value of an output slope of the downstream side sensor finally becomes less than a threshold value in the air-fuel ratio maintenance time period as an end point of cumulative addition of the oxygen excess/deficiency. The threshold value is made larger when a maximum value of the absolute value of the output slope in the air-fuel ratio maintenance time period is relatively large compared to when the maximum value is relatively small.