Exhaust emission control system of engine

An exhaust emission control system of an engine is provided including a NOx catalyst for oxidizing HC and storing NOx within exhaust gas when an air-fuel ratio of the exhaust gas is lean, and reducing the NOx when the air-fuel ratio is approximately stoichiometric or rich. The system includes a SCR...

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Bibliographische Detailangaben
Hauptverfasser: Tetsuno, Masayuki, Kanno, Masanobu, Yamaguchi, Takayuki
Format: Patent
Sprache:eng
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Zusammenfassung:An exhaust emission control system of an engine is provided including a NOx catalyst for oxidizing HC and storing NOx within exhaust gas when an air-fuel ratio of the exhaust gas is lean, and reducing the NOx when the air-fuel ratio is approximately stoichiometric or rich. The system includes a SCR catalyst for purifying NOx by causing a reaction with NH3, a urea injector, a fuel injection controlling module, and a processor configured to execute a NOx reduction controlling module for performing a NOx reduction control to enrich the air-fuel ratio to reach a target ratio. When the urea injection is determined to be abnormal, the NOx reduction controlling module performs a NH3-supplied NOx reduction control in a state where a larger amount of unburned fuel than the amount of unburned fuel in the exhaust passage in the NOx reduction control is supplied to the exhaust passage.