JPS57102508A - Muffler - Google Patents

Abstract

PURPOSE:To enable silencing over a wide range of operation of an engine, by fitting an open area setting pipe slidably on an exhaust gas inlet pipe and by using the pressure of exhaust to change the open area of the exhaust gas expansion/contraction holes of the exhaust gas inlet pipe. CONSTITUTION:The exhust gas of an engine flows through a pipe 15 and the front 2 of a silencer 1 and enters into a pipe 5 having numerous holes 7. When the exhaust gas goes out of the holes 7, interference takes place in an expansion chamber. When the exhaust gas enters into a pipe 6 having holes 8, the gas contracts so that noises are eliminated. After that, exhaust gas is released to the outside through the rear 3. The pipes 5, 6 are an indentical pipe provided with a partition wall 13 inside. An open area setting pipe 10 is provided on the peripheral surface of the pipes 5, 6 to shut off the holes 7, 8. The open area setting pipe 10 is caused to slide by a diaphragm-type control valve driven by the exhaust pressure through a rod 18. When the engine rotates slowly and its exhaust pressure is low, the open area of the holes 7, 8 is reduced. When the engine rotates rapidly, the open area is augmented by the exhaust pressure to effectually eliminate a high-frequency range of noises.