PURPOSE: To improve the suction efficiency and scavenging efficiency by arranging the conical guide cylinder and reflection cylinder in an expansion guide at the downstream edge of an exhaust pipe so that the opened port parts having each expanded diameter are opposed and attaching and separating the both cylinders according to the engine operation state.
CONSTITUTION: In an expansion chamber 16 formed at the downstream edge of an exhaust pipe 5, a conical guide cylinder 14 in which a movable cylinder part 17 slidingly contacts a fixed cylinder part 16 and a conical reflection cylinder 25 in which a collar 26 slidingly contacts the second exhaust pipe 8 are installed so as to be shiftable in the exhaust flowing direction 15, and negative pressure waves are generated by the guide cylinder 14, and the positive waves are generated by the reflection cylinder 25. A controller 37 drives servomotors 23 and 34 according to the operation state of an engine 1, and shifts the 34 according to the operation state of the engine 1, and shifts the guide cylinder 14 and the reflection cylinder 25 through the driving members 19 and 30, and changes the generation positions of the negative and positive pressure waves. Thus, the driving parts of the guide cylinder and the reflection cylinder can be made small-sized and lightweight, improving the suction efficiency and scavenging efficiency of the engine body.
SUGIZAKI TEIICHI
NAKAJIMA KOJI
TOTTORI TAKUMI
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