US Patent 7669693 Exhaust muffling device

An object of the present invention is to provide an exhaust muffling device having a simple structure, which is capable of suppressing air column resonance favorably, irrespective of a length of an outlet pipe of an exhaust pipe which communicates with a muffler, and with which it is possible to achieve appropriate reductions in weight and cost. The exhaust muffling device of the present invention comprises a muffler having an expansion chamber whose length is L in an exhaust direction, and an outlet pipe being in communication with the expansion chamber and whose pipe length is approximately 2nL in which n is a natural number.