| 摘要 |
PROBLEM TO BE SOLVED: To effectively utilize exhaust pulsation to improve exhaust emission. SOLUTION: In an exhaust pipe 12 of an engine 11, two catalysts 13, 14 are arranged in series. The upstream catalyst 13 is separated into an upstream catalyst block 17 and a downstream catalyst block 18 to form a space 19 between the catalyst blocks 17, 18. Thereby, the exhaust pulsation generated in an exhaust manifold 15 is propagated in the space 19 between the catalyst blocks 17, 18. The exhaust pulsation causes the exhaust gas in the space 19 to repeatedly flow into downstream portion of the upstream catalyst block 17 and an upstream portion of the downstream catalyst block 18. The carrying amount of noble metal disposed in at least one of the downstream portion of the upstream catalyst block 17 and the upstream portion of the downstream catalyst block 18 is increased. Accordingly, the exhaust pulsation generated in the space 19 between the catalyst blocks 17, 18 is effectively utilized to increase exhaust gas purification rate.
|
