| 摘要 |
<P>PROBLEM TO BE SOLVED: To prevent deterioration of exhaust emission caused by a temporary temperature drop of a main catalyst converter during an engine start. <P>SOLUTION: A small bypass catalytic converter is provided in a bypass passage in parallel with a part of a main passage provided with a main catalytic converter at a downstream thereof as an exhaust emission control device, and a channel change over valve opens and closes the main passage. It is determined that the main catalytic converter is activated and the channel change over valve is opened when main catalyst temperature CATOUT reaches catalyst activation temperature VOPENTEMP1 during cold start or the like. Determination of activation is prohibited and the change over valve is kept close until the main catalyst temperature gets to the minimum point CATOUTmin at which the main catalyst temperature changes from drop to rise when catalyst temperature drop conditions where the main catalyst temperature temporally drops. <P>COPYRIGHT: (C)2010,JPO&INPIT |
