EXHAUST EMISSION CONTROL DEVICE FOR INTERNAL COMBUSTION ENGINE, AND DEVICE AND METHOD FOR CONTROLLING EXHAUST EMISSION CONTROL DEVICE

PROBLEM TO BE SOLVED: To provide a control device and a control method for an exhaust emission control device for an internal combustion engine capable of preventing actual adsorption quantity from getting extremely lower than a saturated adsorption quantity curve even if the catalyst temperature shifts to the low temperature side continuously for a predetermined period of time or longer, and preventing drop of reduction efficiency of NOXcatalyst. SOLUTION: This device is provided with a temperature transition determination means estimating temperature transition of the NOXcatalyst and determining whether temperature of the NOXcatalyst drops continuously for the predetermined period of time or longer, a first injection control means injecting reducer according to first target adsorption quantity of a value smaller than saturated adsorption quantity of reducer corresponding to temperature of the NOXcatalyst when it is determined that temperature of the NOXcatalyst does not drop continuously for the predetermined period of time or longer, and a second injection control means injecting reducer according to a second target adsorption quantity of a value smaller than the saturated adsorption quantity and larger than the first target adsorption quantity when it is determined that temperature of the NOXcatalyst drops continuously for the predetermined period of time or longer. COPYRIGHT: (C)2009,JPO&INPIT