Exhaust emission purification device for internal combustion engine

摘要

In order to suppress the deterioration of the detection accuracy of a PM sensor (17), provided is an exhaust emission purification device for an internal combustion engine comprising a NOx catalyst (7) that is provided in an exhaust channel (3) of an internal combustion engine (1) and reduces NOx by way of a supplied reducing agent, a supply device (6) that supplies urea to the NOx catalyst (7) from the upstream-side of the NOx catalyst (7), and a PM sensor (17) that detects the amount of particulate matter in the exhaust downstream from the NOx catalyst (7), wherein a control unit (10) is provided that controls the supply of urea from the supply device (6) when the amount of particulate matter adhering to the NOx catalyst (7) is greater than or equal to a threshold value.