| 摘要 |
<P>PROBLEM TO BE SOLVED: To prevent a secondary-air valve 22 from causing a sticking fault or thermal degradation due to backward flow of exhaust gas. <P>SOLUTION: The secondary-air valve 22 is opened under a warm-up condition to supply secondary air from an air pump 12 to an exhaust passage via a discharge port 11 of a secondary-air gallery 10, thereby promoting the activation of a catalyst. In the present invention, the secondary-air valve 22 is opened to circulate secondary air under a predetermined high-load operating condition with a high flow rate. This stops exhaust gas from flowing back and contributes to cooling. <P>COPYRIGHT: (C)2009,JPO&INPIT |
