| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an exhaust emission control device capable of reducing the discharge level of HC and NOx by reasonably supplying oxygen corresponding to desorption of HC when providing an HC adsorptive catalyst which adsorbs HC under exhaust in a cooled condition and desorbs and purifies HC at the temperature not lower than the HC desorption starting temperature T1 in an exhaust passage of an engine. <P>SOLUTION: The temperature of an HC adsorption catalyst is detected or estimated. The air-fuel ratio is gradually shifted to the lean side from the HC desorption starting temperature T1 so as to respond to the increase of the desorption. The lean-shift quantity of the air-fuel ratio is maintained at a predetermined maximum value between the temperature T2 at which the desorption reaches a peak and the temperature T3 at which the desorption is started to decrease. The lean-shift quantity is gradually reduced so as to return to stoichiometric amount of air at the desorption completion temperature T4. <P>COPYRIGHT: (C)2005,JPO&NCIPI |
