EXHAUST PURIFICATION SYSTEM

摘要

The present invention makes it possible to prevent an excessive exhaust temperature increase when HC is supplied to an oxidation catalyst, and to effectively suppress thermal degradation of an SCR catalyst. The invention is provided with: a first oxidation catalyst (31) that is provided in an exhaust system of an internal combustion engine (10); a second oxidation catalyst (32) that is provided in the exhaust system downstream of the first oxidation catalyst (31); a selective reduction catalyst (41) that is provided in the exhaust system downstream of the second oxidation catalyst (32) and reduces and purifies NOx in the exhaust using NH3 generated from urea water as a reducing agent; a third exhaust temperature sensor (53) that detects the temperature of the exhaust flowing into the selective reduction catalyst (41); a temperature increase control unit (62) that periodically implements temperature increase control in which HC is supplied to the first oxidation catalyst (31) to increase the exhaust temperature detected by the third exhaust temperature sensor (53) to a prescribed target temperature; and a target temperature correction unit (63) that, on the basis of the difference between the target temperature and the exhaust temperature detected by the third exhaust temperature sensor (53) during the implementation of temperature increase control, corrects the target temperature for the temperature increase control that is to be implemented following the aforementioned temperature increase control.