Various embodiments include a method of ascertaining the oxygen load of a catalytic converter disposed in an exhaust tract of an internal combustion engine with an exhaust gas sensor is disposed downstream of the catalytic converter comprising: generating a signal using the exhaust gas sensor indicating a proportion of nitrogen oxide and/or ammonia in the exhaust gas; and ascertaining the oxygen load of the catalytic converter at least partly on the basis of the signal from the exhaust gas sensor.

An aftertreatment system configured to reduce constituents of an exhaust gas produced by an engine comprises an aftertreatment component and an optical assembly. The optical assembly comprises an optical emitter configured to emit light onto a face of the aftertreatment component, and an optical detector configured to detect light reflected from the face of the aftertreatment component. A controller is configured to determine at least one of an amount of NOx gases or an amount of ammonia on the face of the aftertreatment component based on an optical parameter of the detected light that has reflected from the face of the aftertreatment component.

A post-treatment system includes two SCRs, a second SCR is connected to a booster in parallel, and a three-way valve is arranged before the second SCR and the booster, such that whether an exhaust gas flows through the second SCR or the booster is controlled by means of controlling the three-way valve. In the case of a low temperature, the three-way valve is controlled to close a branch of the booster, such that the exhaust gas flows through the second SCR and a first SCR that are connected in series, thereby reducing the energy loss caused by the exhaust gas flowing through the booster, and improving the NO.sub.x conversion efficiency in the case of a low temperature. In a case of a high temperature, the three-way valve is controlled to close a by-pass line, such that the exhaust gas flows through the booster and the first SCR.

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.

Method for operating an internal combustion engine which has a gas combustion system and an exhaust gas post-treatment system. Exhaust gas that leaves the gas combustion system is directed to at least one CH4 oxidation catalytic converter of the exhaust gas post-treatment system. The CH4/NO2 mole ratio in the exhaust gas is set in a defined fashion by at least one gas-combustion-system-side and/or exhaust-gas-post-treatment-system-side measure upstream of at least one CH4 oxidation catalytic converter.

An exhaust gas treatment device includes a housing having a wall. The wall of the housing defines an interior chamber. A substrate is supported by the housing within the interior chamber of the housing. The substrate extends along a longitudinal axis. The substrate includes a flow through structure that allows the flow of exhaust gas to flow through the substrate. The substrate includes a catalytic composition disposed thereon for reacting with the flow of exhaust gas. The substrate includes a cavity, extending along a cavity axis, which is transverse to the longitudinal axis of the substrate. A sensor is attached to the housing. The sensor includes a probe that at least partially extends into the cavity of the substrate, for sensing a gaseous component in the flow of exhaust gas. The cavity mixes the flow of exhaust gas and directs the exhaust gas toward the probe of the sensor.

Provided is a method for diagnosing whether an oxidation catalyst has degraded, based on an output value from one diagnostic sensor with higher accuracy. When a ratio of nitrogen monoxide that is oxidized by a catalyst and discharged downstream of the catalyst as nitrogen dioxide, with respect to nitrogen monoxide contained in an exhaust gas supplied upstream of the catalyst in an exhaust path is defined as a NO conversion rate, a diagnostic sensor configured to output an electromotive force corresponding to the NO conversion rate as a diagnostic output is provided downstream of the catalyst in the exhaust path, and whether the catalyst has degraded beyond an acceptable limit is diagnosed by comparing the diagnostic output with a threshold value predetermined depending on a temperature of the catalyst.

A method to reduce NOx breakthrough and NH3 slip is provided when the SCR system is increasing in temperature and/or increasing exhaust gas mass flow. The method includes the steps of monitoring states of parameters of the exhaust gas upstream of an SCR catalyst where the states of parameters include at least one of the inlet temperature or the exhaust gas mass flow; identifying one of a temperature increase or an increased exhaust gas mass flow at the SCR inlet; identifying a new lower ammonia set-point or storage concentration for the SCR; and identifying the rate of NH3 consumption. The method further includes the step of determining an “intervening phase” a small dosage of DEF is continued during the intervening phase.

A controller for controlling regeneration of a selective catalytic reduction (SCR) catalyst of an aftertreatment system is configured to cause increase in a SCR catalyst temperature of the SCR catalyst to a first regeneration temperature, the first regeneration temperature being lower than a high regeneration temperature that is equal to or greater than 500 degrees Celsius. The controller is configured to determine an amount of ammonia slip downstream of the SCR catalyst; and cause an increase in the SCR catalyst temperature to a second regeneration temperature greater than the first regeneration temperature but lower than the high regeneration temperature based on the determined amount of ammonia slip.