| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a control device for an internal combustion engine capable of regenerating a particulate collection filter without increasing emission of nitrogen oxide. <P>SOLUTION: This control device includes an upstream air-fuel ratio sensor 66, an upstream catalyst 53, the particulate collection filter 54, a downstream air-fuel ratio sensor 67, and a downstream catalyst 55 successively disposed in an exhaust passage of an internal combustion engine 10 from the upstream side toward the downstream side. In a period after completion of fuel cut operation, the control device controls averaged air-fuel ratio of the engine to a first air-fuel ratio which falls within a window of the downstream catalyst 55 and is shifted toward the rich side from the stoichiometric air-fuel ratio. When the downstream catalyst is determined to have reached a reduced state in which the downstream catalyst can remove a predetermined amount of nitrogen oxides, the control device controls the averaged air-fuel ratio of the engine to a second air-fuel ratio shifted toward the lean side from the stoichiometric air-fuel ratio. With this operation, oxygen is supplied to the particulate collection filter, whereby particulates therein are burned, and nitrogen oxides are removed by the downstream catalyst. <P>COPYRIGHT: (C)2009,JPO&INPIT</p> |
