| 摘要 |
An object of the present invention is to reduce oxide stored in an NOx catalyst in a more preferable manner. According to the present invention, when oxide stored in the NOx catalyst is to be reduced, the combustion mode of the internal combustion engine is switched into a low air-fuel ratio mode in which the air-fuel ratio of the air-fuel mixture in the internal combustion engine is low, and supply of fuel is executed at a time when the air-fuel ratio of the exhaust gas has been made low by the switching of the combustion mode.
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