EXHAUST PURIFICATION APPARATUS FOR INTERNAL COMBUSTION ENGINE

摘要

The purpose of the present invention is to suppress degradation of a PM sensor and a decrease in detection accuracy of the amount of PM in a configuration in which a urea addition unit and a selective reduction type NOx catalyst (NOx catalyst) are provided downstream of a particulate filter (filter) in an internal combustion engine exhaust passageway, the PM sensor being disposed downstream of the filter. According to the present invention, in an exhaust passageway (2) of an internal combustion engine (1), a first NOx catalyst (4) and a second NOx catalyst (5) are disposed downstream of a filter (3) successively from the upstream side along the flow of exhaust. A urea addition unit (6) is disposed between the filter (3) and the first NOx catalyst (4). A PM sensor (7) is disposed between the first NOx catalyst (4) and the second NOx catalyst (5).