Exhaust emission control device of internal combustion engine

摘要

An exhaust gas purification device of an internal combustion engine arranging a catalyst (22) suitable for reduction of NOx in exhaust gas by ammonia in the presence of excess oxygen in an engine exhaust passage, said device comprising: feeding means (31,32,33) for feeding a liquid (30) containing an ammonia generating compound to the catalyst; feed control means (40) for controlling the amount of feed of the liquid; decision means (40) for deciding if the temperature of the catalyst is in an ammonia generating compound storage region or if the temperature of the catalyst is in an ammonia release region which causes the ammonia to be released a little at a time from the stored ammonia generating compound; wherein said feed control means (40) feeds a sufficient amount of the liquid required to the catalyst in the form of pulses at time intervals when the temperature of the catalyst is in the ammonia generating compound storage region, said sufficient amount of the liquid being necessary to store in the catalyst in advance enough of the ammonia generating compound for releasing the amount of ammonia required when the temperature of the catalyst becomes the ammonia release region.