| 摘要 |
<P>PROBLEM TO BE SOLVED: To securely release NOx from a NOx occlusion catalyst without increasing the amount of addition of hydrocarbons. <P>SOLUTION: A fuel injection valve 3 which directly injects fuel into a cylinder is provided, and an HC adsorption catalyst 11 and the NOx occlusion catalyst 12 are arranged in the order directed toward the downstream side within an exhaust passage of an internal combustion engine. Then the HC adsorption catalyst 11 has the function of gradually vaporizing the fine-grain-shaped fuel after adsorbing and retaining the fine-grain-shaped fuel added to the exhaust gases. At the time when NOx should be released from the NOx occlusion catalyst 12, auxiliary fuel is injected from the fuel injection valve 3 into an expansion process or an exhaust process of the internal combustion engine so that the air/fuel ratio of a gaseous ingredient in the exhaust gases leaking from the HC adsorption catalyst 11 becomes rich. When the temperature of the HC adsorption catalyst 11 is high, the injection timing of the auxiliary fuel is retard-angle corrected. <P>COPYRIGHT: (C)2006,JPO&NCIPI |
