Patent ID: 7797097

Claim:
An exhaust purification device of an internal combustion engine that has a rich combustion means for lengthening a period of fuel injection or for performing a subsidiary injection immediately after the fuel injection, a reducing agent addition means for adding a reducing agent directly upstream of a NOx occlusion reduction type catalyst, and a post-injection means for performing a subsidiary injection in an expansion stroke or an exhaust stroke after the fuel injection and that switches between the rich combustion means and the reducing agent addition means or the post-injection means in accordance with engine rotation speed and a load, whereby the exhaust purification device controls the catalyst, the exhaust purification device comprising: a particulate matter discharge quantity measurement section for measuring a discharge quantity of particulate matters; a particulate matter discharge quantity determination means for determining whether the discharge quantity of the particulate matters measured with the particulate matter discharge quantity measurement section is greater than a first predetermined value; and a second catalyst reduction setting means for changing the engine rotation speed and the load for performing the rich combustion means to a low rotation speed side or a low load side when the particulate matter discharge quantity determination means determines that the discharge quantity of the particulate matters is greater than the first predetermined value.