Engine exhaust noise suppressor

摘要

The inner area of a muffler of an engine is partitioned into an expansion chamber, a first volume chamber and a second volume chamber. An inlet tube and the first volume chamber are connected by a first passage. The first volume chamber and a second volume chamber are connected by a second passage, and the second volume chamber and expansion chamber are connected by a third passage. The flow of exhaust gas reaching the expansion chamber via the first passage, second passage and third passage is blocked by a valve which opens according to a pressure rise of the exhaust gas. One of the two acoustic paths formed when the valve is open functions as a resonator having two degrees of freedom relative to the other path so that a high muffling effect is obtained.