| 摘要 |
<P>PROBLEM TO BE SOLVED: To prevent outward discharge of ammonia produced by sublimation of a deposit, by enabling reliable removal of deposit produced and accumulated in an urea decomposition process. <P>SOLUTION: An exhaust emission control device of an internal combustion engine, which has an NOx selective-reduction catalyst (36) provided in an exhaust passage (18), includes: an exhaust air reflux passage (44) which bypasses the NOx selective-reduction catalyst; a reflux control valve (48) which opens/closes the exhaust air reflux passage; an amount-of-accumulated-deposit estimation means (58) for estimating the amount of accumulated deposit formed along with decomposition of a reductant solution; and a deposit sublimation means (57) for sublimating the accumulated deposit by heating it. When the amount of accumulated deposit, which is estimated by the amount-of-accumulated-deposit estimation means, exceeds a threshold, the accumulated deposit is heated and sublimated by the deposit sublimation means, and a state of the reflux control valve is switched to a valve-opened state. <P>COPYRIGHT: (C)2013,JPO&INPIT |
