| abstract |
The invention relates to a method for exhaust aftertreatment of an internal combustion engine (10) at whose outlet (12) an exhaust system (20) is connected. Here, in the exhaust system (20) downstream of the outlet (12) close to the engine, a first catalyst (22), preferably a three-way catalyst (26) and downstream of the first catalyst (22), preferably in Unterbodenlage the motor vehicle, a second catalyst (24), in particular a four-way catalyst (28). In the flow direction of an exhaust gas through the exhaust system (20) downstream of the first catalyst (22) and upstream of the second catalyst (24) a discharge point (42) is provided for secondary air, at the point of introduction (42) secondary air is blown into the exhaust system, if a substoichiometric exhaust gas is detected downstream of the first catalyst (22). In this case, the injection of secondary air is terminated when a stoichiometric exhaust gas is detected upstream of the first catalyst (22) or when a displacement of the exhaust air ratio lean in the exhaust system (20) downstream of the first catalyst (22) and upstream of the second catalyst (24 The invention further relates to an exhaust aftertreatment system which is adapted to carry out such a method. |