| abstract |
Micropore zones ZMI are defined at upstream sides of partition walls 72 of a particulate filter and macropore zones ZMA are defined at downstream sides of partition walls. The pore size of the partition walls at the micropore zones is set so that the particulate matter and the ash can be trapped by the partition walls at the micropore zones, while the pore size of the partition walls at the macropore zones is set so that the ash can pass through the partition walls at the macropore zones. When a quantity of trapped particulate matter is smaller than a limit quantity, control for increasing gas which temporarily increases the flow rate of the gas which flows into the particulate filter in order to remove the ash from the particulate filter, is performed. |