EXHAUST PURIFICATION DEVICE FOR INTERNAL COMBUSTION ENGINE

摘要

In order to prevent a decrease in the accuracy with which filter malfunctions are determined due to a decrease in the detection accuracy of a PM sensor, the present invention is equipped with: a filter that is provided in the exhaust passage of an internal combustion engine, and that traps particulate matter in the exhaust; a selective reduction NOx catalyst that is provided downstream from the filter, and that reduces NOx by means of a supplied reduction agent; a supply device that supplies the reduction agent to the selective reduction NOx catalyst from the upstream side of the selective reduction NOx catalyst; a PM sensor that is downstream from the selective reduction NOx catalyst, and that detects the amount of particulate matter in the exhaust; and a prohibition unit that prohibits the use of the detection value of the PM sensor when the reduction agent supplied from the supply device passes through the selective reduction NOx catalyst.