Patent ID: 7669693

Claim:
An exhaust muffling device comprising: a muffler having an expansion chamber whose length is L in an exhaust direction; an inlet pipe having a first open end and a second open end, the first open end in direct communication with an outside of the muffler and the second open end in direct communication with the expansion chamber; and an outlet pipe having a first open end face, a second open end face and a through hole formed in a peripheral wall of the outlet pipe near the first open end face, the outlet pipe having no openings in the peripheral wall from the through hole to the second open end face, wherein the first open end face is in direct communication with the expansion chamber, the through hole is in communication with an inside of the muffler, an exhaust gas is exhausted from the outlet pipe into an atmosphere, and a length of the outlet pipe from the through hole to the second open end face is approximately 2nL and is based on the length L of the expansion chamber, a natural number n, and an open end correction of the outlet pipe so as to suppress air column resonance.