| 摘要 |
<P>PROBLEM TO BE SOLVED: To reduce emission by secondary air while preventing an excessive temperature rise in a catalyst regardless of an operation condition in an internal combustion engine mounted with a secondary air supply system. <P>SOLUTION: This exhaust emission control device is provided with an upstream side secondary air supply nozzle 17 for supplying the secondary air 13 delivered from an air pump 16 to the upstream side of the catalyst 13, a downstream side secondary air supply nozzle 18 for supplying the secondary air to the downstream side of the catalyst 13 and a supply destination switching valve 19 for switching a supply destination of the secondary air. When the temperature of the catalyst 13 is not raised to the active temperature, the secondary air is supplied to the upstream side of the catalyst 13. After the temperature of the catalyst 13 rises to the active temperature, the excessive temperature rise in the catalyst 13 is prevented by stopping supply of the secondary air to the upstream side of the catalyst 13. When increasing a quantity of high load fuel, a rich component unpurified by the catalyst 13 is purified by reacting with oxygen of the secondary air by oxidation on the downstream side of the catalyst 13 by supplying the secondary air to the downstream side of the catalyst 13. <P>COPYRIGHT: (C)2007,JPO&INPIT |
