Patent ID: 6394225
Filing Date: 2002-05-28
Classification: F01N

Abstract:
A muffler structure in which a sound absorbing material is laid on the inside surface of an outer tube; said sound absorbing material is retained by an inner tube made of a metal that is punched with a plurality of holes; said inner tube is separated into a plurality of expansion chambers; and exhaust gas from an engine is directed into a first of said plurality of expansion chambers by an inlet pipe, being discharged out after being supplied to others of said plurality of expansion chambers one after another through at least one connecting pipe, said muffler structure comprises:said inner tube is made of an approximately flat metal that is punched with a plurality of holes by bending the metal into a circular form until its opposite edges are butted to each other to form a butt portion that is not jointed, said inner tube being fitted in said outer tube, so that said butt portion is positioned behind said connecting pipe when viewed from said inlet pipe side.