EXHAUST EMISSION CONTROL DEVICE OF INTERNAL COMBUSTION ENGINE

摘要

PROBLEM TO BE SOLVED: To provide an exhaust emission control device of an internal combustion engine which maintains the temperature of a catalyst in an adequate range when controlling decomposition and removal of SOx or the like deposited on a NOx catalyst in an exhaust system of the internal combustion engine.

SOLUTION: An ECU 90 to collectively control a running condition of an engine 1 decomposes and emits SOx deposited on the NOx catalyst by performing the control to feed a large volume of fuel through a reducing agent applying valve 17 to the upstream side of the NOx catalyst in the exhaust system 40 while establishing a condition that the bed temperature of the NOx catalyst is maintained at 600°C or over. Based on the property of the NOx catalyst and the exhaust characteristic in performing the control, the optimum fuel feed and stop timing is set taking into consideration the responsiveness of the NOx catalyst bed temperature to the operation of the reducing agent applying valve 17. By constructing this control structure, the catalyst is reliably prevented from being excessively heated while efficiently emitting SOx deposited on the NOx catalyst.

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