| 摘要 |
PROBLEM TO BE SOLVED: To perform a superior sound adjustment at an exhaust muffler in which a sound muffling characteristic is made variable due to variation in a flowing passage for exhaust gas discharged out of an internal combustion engine.SOLUTION: A down-stream chamber 36 and an up-stream chamber 37 are formed within a casing 26, exhaust gas discharged out of an internal combustion engine can be fed into one end part of a first conduit 28 and one end part of a second conduit 29 provided with a punched hole part 40 composed of a plurality of communication holes 39 communicated with the down-stream chamber 36, the other ends of the first and second conduits 28 and 29 are opened at the up-stream chamber 37, valve means 30 placed more up-stream side than the punched hole part 40 enabling the first conduit 28 to be opened or closed and the second conduit 29 to be opened or closed changes over a short passage state in which the exhaust gas discharged out of an internal combustion engine is discharged to outside from at least the first conduit 28 through the punched hole part 40, the down-stream chamber 36 and an exhaust pipe 27 and a long passage state in which the exhaust gas discharged out of the internal combustion engine is discharged to outside from the second conduit 29 through the up-stream chamber 37, the punched hole part 40, the down-stream chamber 36 and the exhaust pipe 27 and driven by valve driving means 31.SELECTED DRAWING: Figure 2 |
