| 摘要 |
PROBLEM TO BE SOLVED: To increase purification efficiency in steps by including a close- coupled(CC) catalyst maximizing the activity at a low temperature, an HC adsorption unit catalyst device removing HC, an electrically heated catalyst(EHC) removing the HC desorbed at a high temperature, and a light-off catalyst. SOLUTION: The exhaust gas passing through an exhaust manifold 30 passes through a close-coupled(CC) catalyst 40 removing HC. The HC exhausted due to deficient activation at a low temperature is removed by an HC adsorbing unit catalyst device 50 fitted at an underfloor position. The HC adsorbing unit catalyst device 50 is combined with an HC adsorbing unit capable of efficiently adsorb HC to remove it and a three-way catalyst for increasing purification efficiency for HC and NOx. An electrically heated catalyst(EHC) 60 and a fast light-off catalyst 70 are fitted behind the HC adsorbing unit catalyst device 50. When the HC is desorbed from the adsorbing unit and discharged as the temperature of the exhaust gas is increased, the HC and NOx can be effectively removed.
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