| 摘要 |
PROBLEM TO BE SOLVED: To reduce exhaust quantity of HC(hydrocarbon) reserved in a suction air passage while an engine stops to the atmospheric air. SOLUTION: An HC adsorbent 18 is provided in a surge tank 15, and an opening and closing valve 20 to change a contact degree of intake air and the HC adsorbent 18 is provided on the upstream side of this HC adsorbent 18. Residual HC in a suction air passage is adsorbed by the HC adsorbent 18 while the engine stops, and HC is release from the HC adsorbent 18 by increasing the contact degree of the intake air and the HC adsorbent 18 by opening the opening and closing valve 20 after a catalyst 22 comes to be in an active state after starting. Consequently, it is possible to purify HC by the catalyst 22 in the active state even when HC released from the HC adsorbent 18 is not sufficiently burnt in a cylinder and discharged to an exhaust pipe 21. Additionally, HC release reduces and corrects fuel injection quantity in accordance with release quantity of HC from the HC adsorbent 18 and prevents slippage of an air-fuel ratio of exhaust gas from a target air-fuel ratio (purifying window of the catalyst 22). |
