Operating Method for a Motor Vehicle Diesel Engine Having an Exhaust Emission Control System

An operating method is provided for a motor vehicle diesel engine having an exhaust emission control system that includes a three-way catalytic converter and an SCR catalytic converter situated one behind the other in the flow direction of the exhaust gas. The diesel engine is operated, at least int...

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Hauptverfasser: BALTHES ORTWIN, KEPPELER BERTHOLD, MUELLER SIEGFRIED
Format: Patent
Sprache:eng
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Beschreibung
Zusammenfassung:An operating method is provided for a motor vehicle diesel engine having an exhaust emission control system that includes a three-way catalytic converter and an SCR catalytic converter situated one behind the other in the flow direction of the exhaust gas. The diesel engine is operated, at least intermittently, with an air-fuel ratio of approximately lambda=1.0 in a first operating range in which the SCR catalytic converter falls below a predefinable minimum temperature and with excess air that is typical for normal diesel engine operation in a second operating range in which the SCR catalytic converter exceeds the predefinable minimum temperature. An output signal of an exhaust gas sensor situated downstream from the three-way catalytic converter and which is correlated with a NOx concentration of the exhaust gas is used to set the air-fuel ratio in the first operating range.