The present invention relates to a method for adaption of an exhaust treatment system arranged for treating an exhaust stream produced by an engine, where the exhaust treatment system includes at least a first additive dosage device, a first selective catalytic reduction catalyst arranged downstream of the first additive dosage device, a second additive dosage device arranged downstream of the first selective catalytic reduction catalyst, and a second selective catalytic reduction catalyst arranged downstream of the second additive dosage device. The method includes initiating an adaption of the second selective catalytic reduction catalyst, and controlling, during the adaption of the second selective catalytic reduction catalyst, the first additive dosage device to inject additive in accordance with at least one injection rule being designed for the adaption.

A method for diagnosing NOx sensors in an exhaust aftertreatment system includes suspending reductant dosing in an exhaust aftertreatment system; purging a reductant deposit in a selective catalytic reduction (SCR) system of the exhaust aftertreatment system; adjusting at least one of an ignition timing and an engine speed for an engine to adjust an engine out nitrogen oxide (NOx) amount; receiving measured SCR inlet NOx data from a SCR inlet NOx sensor and measured SCR outlet NOx data from a SCR outlet NOx sensor; determining a phase shift between the measured SCR inlet and SCR outlet NOx data; applying the determined phase shift to the SCR outlet NOx data; and determining a diagnostic feature based on the SCR inlet NOx data and the phase shifted SCR outlet NOx data regarding a state of the SCR inlet and outlet NOx sensors.

A control device for an internal combustion engine is provided with a target air-fuel ratio setting part including a first setting control part performing normal control alternately switching a target air-fuel ratio between a predetermined first lean air-fuel ratio and a predetermined first rich air-fuel ratio and a second setting control part performing control for restoration of the storage amount stopping normal control and increasing the oxygen storage amount of a second catalyst when an output air-fuel ratio of a third air-fuel ratio sensor becomes a predetermined rich judgment air-fuel ratio or less. Further, the second setting control part is configured to set the target air-fuel ratio to a predetermined second lean air-fuel ratio larger than the first lean air-fuel ratio at the time of start of the control for restoration of the storage amount and set the target air-fuel ratio to a predetermined third lean air-fuel ratio smaller than the second lean air-fuel ratio after an exhaust with a larger air-fuel ratio than the stoichiometric air-fuel ratio flows out from the first catalyst in the time period of setting the target air-fuel ratio to the second lean air-fuel ratio.

A controller for controlling operation of an aftertreatment system that is configured to treat constituents of an exhaust gas produced by an engine, the aftertreatment system including a selective catalytic reduction (SCR) catalyst, the controller configured to: generate a short-term cumulative degradation estimate of the SCR catalyst corresponding to reversible degradation of the SCR catalyst due to sulfur and/or hydrocarbons based on a SCR catalyst temperature parameter; generate a long-term cumulative degradation estimate of the SCR catalyst corresponding to thermal aging of the SCR catalyst based on the SCR catalyst temperature parameter; generate a combined degradation estimate of the SCR catalyst based on the short-term cumulative degradation estimate and the long-term cumulative degradation estimate; and adjust an amount of reductant and/or an amount of hydrocarbons inserted into the aftertreatment system based on the combined degradation estimate of the SCR catalyst.

A first gas sensor having a first sensor element includes a first protective cover that protects the first sensor element, and a second gas sensor having a second sensor element includes a second protective cover that protects the second sensor element. The first protective cover is coated with an oxidation catalyst for one target component from among a plurality of target components, and the second protective cover is coated with an inert catalyst for the one target component.

The invention relates to a method (200) for operating an internal combustion engine (110) having at least one catalytic converter (122), wherein control interventions of a lambda control for controlling an exhaust gas composition of the internal combustion engine are deactivated, comprising ascertaining a current exhaust gas composition upstream of the at least one catalytic converter (122), determining a current oxygen fill level of the at least one catalytic converter (122) on the basis of the ascertained current exhaust gas composition, ascertaining (210) a planned control intervention on a composition of an air-fuel mixture supplied to the internal combustion engine (110) on the basis of the determined current oxygen fill level of the at least one catalytic converter, ascertaining a current exhaust gas composition (123) downstream of the at least one catalytic converter (122), ascertaining a future exhaust gas composition (123) downstream of the at least one catalytic converter (122) resulting on the basis of an air-fuel mixture already supplied to the internal combustion engine (110), and reactivating the lambda control and specifying (260) a control intervention to be carried out as a function of the planned control intervention and the current exhaust gas composition (123) downstream of the at least one catalytic converter (122), and/or as a function of the planned control intervention and the future exhaust gas composition. Furthermore, a processing unit (130) and a computer program for carrying out such a method (200) are proposed.

A method for diagnosing a NOx sensor is provided. The method includes receiving data indicative of operating conditions of an engine or an aftertreatment system; determining, during a first period of time, that an amount of NOx output from the aftertreatment system satisfies a low NOx operating mode condition; determining, during a second period of time, that operating conditions for ammonia slip are present based on data regarding operation of the aftertreatment system; responsive to the determination that operating conditions for ammonia slip are present, determining that the amount of NOx output from the aftertreatment system satisfies a high NOx operating mode condition; comparing a difference between a minimum value from the first period of time and a maximum value from a second period of time to a diagnostic threshold; and responsive to the difference being less than the diagnostic threshold, setting an alert.

A method for ascertaining an exhaust gas composition of an exhaust gas of an internal combustion engine with regard to an ammonia fraction and a nitrogen oxides fraction in an exhaust gas system including an SCR catalytic converter. The method includes detecting, using a sensor, a first signal whose magnitude is a function of the nitrogen oxides fraction of the exhaust gas upstream from the SCR catalytic converter, detecting using a sensor a second signal whose magnitude is a function of the ammonia fraction and the nitrogen oxides fraction of the exhaust gas downstream from the SCR catalytic converter, storing the two signals over an observation period, and ascertaining the ammonia fraction and optionally the nitrogen oxides fraction of the exhaust gas downstream from the at least one SCR catalytic converter using a calculation rule that uses the two signals during the observation period as input variables.

An exhaust gas aftertreatment system for an internal combustion engine has an exhaust system that can be connected to an outlet of the internal combustion engine. A three-way catalytic converter that is situated close to the engine and, downstream from the three-way catalytic converter that is situated close to the engine, a second catalytic converter and a particle reduction device are arranged in the direction in which an exhaust gas of the internal combustion engine flows through an exhaust gas channel of the exhaust system. A fuel injector is arranged on the exhaust gas channel so as to inject fuel downstream from the three-way catalytic converter that is situated close to the engine and upstream from the second catalytic converter, and the exhaust system comprises a secondary air system with which secondary air can be blown into the exhaust gas channel downstream from the three-way catalytic converter that is situated close to the engine and upstream from the second catalytic converter.

An internal combustion engine arrangement includes an internal combustion engine, a catalytic converter, and a controller. The controller is configured to determine a maximum H.sub.2 production capacity of the catalytic converter. The catalytic converter is arranged downstream of the internal combustion engine. The controller is configured and adapted to determine the maximum H.sub.2 production capacity of the catalytic converter based on a first function that correlates an H.sub.2 production of the internal combustion engine with first internal combustion engine parameters.