Abstract: A method for operating an internal combustion engine having a lean NOx trap connected downstream is provided. The method comprises in a normal operating mode, operating the internal combustion engine with a lean fuel/air mixture, and in a special operating mode, operating the internal combustion engine with a rich fuel/air mixture in order to bring about regeneration of the lean NOx trap, wherein a changeover from the normal operating mode to the special operating mode takes place when switching off of the internal combustion engine is expected.

Abstract: Methods and systems are provided for regenerating a particulate filter in an engine exhaust, where burning of soot is initiated by introducing additional oxygen into the exhaust gas upstream of the particulate filter where an exhaust temperature exceeds a threshold, a soot burn rate controlled by adjusting pulsing of the additional oxygen. Further, the pulsing of the additional oxygen is introduced via a high-pressure EGR passage during boosted engine conditions.

Abstract: Embodiments for reducing ammonia slip are provided. In one example, a method for reduction of ammonia emissions from an engine exhaust gas aftertreatment device with an SCR catalyst comprises determining a concentration of NOx and/or ammonia in the exhaust gas aftertreatment device, comparing a determined value of NOx and/or ammonia concentration with a nominal value for NOx and ammonia, respectively, and if an actual or shortly forecasted ammonia concentration is above the respective nominal value, triggering engine conditions with higher exhaust NOx concentration. In this way, ammonia slip may be reduced without degrading fuel economy.

Abstract: Systems and methods for estimating an efficiency of a catalyst placed in an exhaust path of a combustion engine are disclosed. In one example approach, a method comprises: ageing the catalyst consecutively at different temperatures for definite time periods; measuring the catalyst conversion efficiency after each ageing step; calculating the ageing factor for each step of the ageing procedure and the accumulative value of the ageing factors for all steps of the ageing procedure; estimating catalyst efficiency correlation factors related to the measured catalyst conversion efficiency for each temperature point and for all ageing conditions; determining a correlation between the catalyst efficiency correlation factors and the accumulative value of the ageing factors; and calculating the conversion efficiency of the aged catalyst based on a predetermined correlation between the accumulative ageing factor and the catalyst efficiency correlation factor.

Abstract: A method for operating an internal combustion engine having a lean NOx trap connected downstream is provided. The method comprises in a normal operating mode, operating the internal combustion engine with a lean fuel/air mixture, and in a special operating mode, operating the internal combustion engine with a rich fuel/air mixture in order to bring about regeneration of the lean NOx trap, wherein a changeover from the normal operating mode to the special operating mode takes place when switching off of the internal combustion engine is expected.

Abstract: Methods and systems are provided for regenerating a particulate filter in an engine exhaust, where burning of soot is initiated by introducing additional oxygen into the exhaust gas upstream of the particulate filter where an exhaust temperature exceeds a threshold, a soot burn rate controlled by adjusting pulsing of the additional oxygen. Further, the pulsing of the additional oxygen is introduced via a high-pressure EGR passage during boosted engine conditions.

Abstract: Systems and methods for estimating an efficiency of a catalyst placed in an exhaust path of a combustion engine are disclosed. In one example approach, a method comprises: ageing the catalyst consecutively at different temperatures for definite time periods; measuring the catalyst conversion efficiency after each ageing step; calculating the ageing factor for each step of the ageing procedure and the accumulative value of the ageing factors for all steps of the ageing procedure; estimating catalyst efficiency correlation factors related to the measured catalyst conversion efficiency for each temperature point and for all ageing conditions; determining a correlation between the catalyst efficiency correlation factors and the accumulative value of the ageing factors; and calculating the conversion efficiency of the aged catalyst based on a predetermined correlation between the accumulative ageing factor and the catalyst efficiency correlation factor.

Abstract: Embodiments for reducing ammonia slip are provided. In one example, a method for reduction of ammonia emissions from an engine exhaust gas aftertreatment device with an SCR catalyst comprises determining a concentration of NOx and/or ammonia in the exhaust gas aftertreatment device, comparing a determined value of NOx and/or ammonia concentration with a nominal value for ammonia and NOx, respectively, and if an actual or shortly forecasted ammonia concentration is above the respective nominal value, triggering engine conditions with higher exhaust NOx concentration. In this way, ammonia slip may be reduced without degrading fuel economy.

Abstract: The present application relates to a method of controlling urea dosing in an exhaust system of a vehicle. The method includes adjusting the urea dosing based on the severity of urea deposition on an SCR catalyst, where the urea dosing is reduced as the severity increases.