EXHAUST EMISSION CONTROL DEVICE FOR INTERNAL COMBUSTION ENGINE

摘要

PROBLEM TO BE SOLVED: To provide an exhaust emission control device for an internal combustion engine achieving both control over temperature of an exhaust emission control catalyst to a target temperature and sufficient conversion of NOx in exhaust gas in the exhaust emission control device for the internal combustion engine controlling the temperature of the exhaust emission control catalyst to the target temperature by bank control.

SOLUTION: This exhaust emission control device for the internal combustion engine is provided with an oxygen storage capacity determination means determining the oxygen storage capacity of a rear stage catalyst. When the temperature of the rear stage catalyst is controlled to the target temperature by the bank control, an air-fuel ratio of each cylinder of a first cylinder group and a second cylinder group is controlled by air-fuel ratio control of a first mode suitable for reducing the amount of NOx in exhaust gas led to flow into the rear stage catalyst if the oxygen storage capacity of the rear stage catalyst is larger than a predetermined capacity, and the air-fuel ratio of each cylinder of the first cylinder group and second cylinder group is controlled by air-fuel ratio control of a second mode suitable for controlling the temperature of the rear stage catalyst to the target temperature if the oxygen storage capacity of the rear stage catalyst is smaller than the predetermined capacity.

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