| 摘要 |
PROBLEM TO BE SOLVED: To promote activation of a catalyst device without causing deterioration of fuel economy while securing an ejector effect of a dynamic pressure exhaust system in the case where lean combustion is performed by an engine and other cases.SOLUTION: An exhaust system includes: an exhaust system body that is connected to a plurality of independent exhaust passages connected to an engine; and a catalyst device connected to the exhaust system body. The exhaust system body includes: nozzle portions communicated with the plurality of independent exhaust passages, respectively and including a plurality of nozzle inner passages having downstream portions of which flow passage areas become smaller from the upstream sides toward the downstream sides while downstream ends in the exhaust gas flowing direction are bundled; a cylindrical peripheral wall portion that covers the entire circumferences of the nozzle portions and forms annular gas flow passages on the outer peripheries of the nozzle portions; a gas introduction portion for introducing assist gas for securing performance of the catalyst device to the gas flow passages; and restriction portions each of which is provided downstream of the nozzle portion, has a diameter reduced from the upstream side to the downstream side in the exhaust gas flowing direction and scavenges exhaust gas from other nozzle inner passages and the assist gas from the gas flow passages.SELECTED DRAWING: Figure 1 |
