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 suppressing an end of an addition valve exposed to an inside of an injection passage from being exposed to high temperature exhaust gas and overheated.SOLUTION: The exhaust emission control device includes an exhaust passage 10, a selective reduction catalyst 30, and an injection passage 11 branched from a portion on an upstream side of the selective reduction catalyst 30 in the exhaust passage 10. A urea addition valve 40 is attached to the injection passage 11. A communication passage 12 directly communicating a portion on the upstream side of a branch part in which the injection passage 11 is branched in the exhaust passage 10 with the injection passage 11 without passing through the branch part is provided in the exhaust emission control device. The exhaust emission control device further includes a cooling device 50 for cooling exhaust gas flowing through the communication passage 12, a cooling water pump 51 for circulating the cooling water to the cooling device 50, and a control device 100 for controlling the cooling water pump 51. The control device 100 controls the cooling water pump 51 so that a temperature in the injection passage 11 is maintained to a prescribed level.