EXHAUST EMISSION CONTROL DEVICE FOR INTERNAL COMBUSTION ENGINE

摘要

PROBLEM TO BE SOLVED: To provide an exhaust emission control device for an internal combustion engine, capable of precisely detecting deposition of urea.SOLUTION: An ECU 12 of an exhaust emission control device 2 comprises a determination unit 13 for determining deterioration of an SCR catalyst 8. The determination unit 13 comprises: an NOx amount calculation part 15 for calculating a purification NOx amount purified by the SCR catalyst 8; a consumption ammonia amount calculation part 30 for calculating an NHamount required for the purification of the purification NOx amount; a urea amount calculation part 17 for calculating an effective urea amount required for the generation of the NHamount; a supply ammonia amount calculation part 27 for calculating the NHamount slipped in the SCR catalyst 8; a supply urea amount calculation part 19 for calculating a supply urea amount required for the generation of the slipped NHamount; a urea utilization ratio calculation part 33 for calculating a urea utilization ratio of NHon the basis of the supply urea amount and the effective urea amount; a deposition determination part 35 for determining the deterioration of the SCR catalyst 8 on the basis of the urea utilization ratio.