| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an exhaust emission control device and exhaust emission control method for an internal combustion engine capable of maintaining an NOx elimination ratio as highly as possible while easily suppressing ammonia slip and of appropriately controlling ammonia addition amount regardless of deterioration of a selective reduction type NOx catalyst and variation due to individual differences, in the exhaust emission control device for the internal combustion engine having the selective reduction type NOx catalyst for selectively reducing NOx in exhaust gas using ammonia as a reducing agent. <P>SOLUTION: By using a polynomial of NOx elimination characteristics, target ammonia adsorption amount to the selective reduction type NOx catalyst is set. When a difference between a reference NOx elimination ratio and an actual NOx elimination ratio exceeds a predetermined value (S10), after ammonia adsorbed in the selective reduction type NOx catalyst is removed once (S16), adaptive estimation calculation of the polynomial is performed based on an actual measurement value of a parameter while injecting urea-water from an injector to update the polynomial (S18, 20). <P>COPYRIGHT: (C)2008,JPO&INPIT |
