Exhaust emission control device for internal combustion engine in bus, has burner which is operated in combustion mode to increase temperature of exhaust gas in exhaust route during forced regeneration of particulate filter

摘要

The temperature of exhaust gas in an exhaust route is increased by operating a burner in combustion mode at the time of forced regeneration of a particulate filter by a regeneration unit. Fuel is supplied to the exhaust route only after switching the burner to fuel supply mode without burning the fuel spray. A detector detects the temperature of the filter. When the detected temperature of the filter reaches the active temperature of an oxidation catalyst, during operation of the burner in combustion mode, the burner is switched to fuel supply mode. The oxidation catalytic converter is interposed at the upstream side of the filter. The regeneration unit is operated by repeating the combustion mode and fuel supply mode.