Patent ID: 7946108

Claim:
A method for regenerating a nitrogen oxide storage catalytic converter arranged in an exhaust pipe of an internal combustion engine, said method comprising: in a first regeneration mode, setting a constant value for an air/fuel ratio λ M of an air/fuel mixture burned in the internal combustion engine when nitrogen oxide concentration in exhaust gas on an output side of the nitrogen oxide storage catalytic converter exceeds a predeterminable triggering threshold value, which triggers a regeneration of the nitrogen oxide storage catalytic converter; and after the first regeneration mode; implementing a second regeneration mode in which a variable value is provided for the air/fuel ratio λ M such that the time rate of change d λ M /dt of the air/fuel ratio λ M is set as a function of one of i) mass flow of the exhaust gas flowing through the nitrogen oxide storage catalytic converter, and ii) an internal combustion engine operating variable linked with the mass flow of the exhaust gas; wherein rising values of the air/fuel ratio λ M are assigned to a higher exhaust gas mass flow than dropping values of the air/fuel ratio λ M .