| 摘要 |
PROBLEM TO BE SOLVED: To sufficiently purify NOX in the wide operation region (in particular, an operation region by extra lean combustion) of a cylinder infection type internal combustion engine, in a emission control system to perform emission control of a cylinder injection type internal combustion engine to inject fuel directly in a combustion chamber. SOLUTION: A lean NOX catalyst 9 to purify mainly NOX is provided in a cylinder injection type internal combustion engine to inject fuel directly in a combustion chamber 1 and switching premixture lean combustion and layer- from lean combustion, and disposed in the exhaust passage 3 of an engine. The lean NOX catalyst 9 comprises a high temperature type lean NOX mainly bringing NOX under emission control and catalyst 9A having a high catalyst activation temperature area; and a low temperature type lean NOX catalyst 9B having a catalyst activation temperature area being lower than that of the catalyst 9A. |
