Patent ID: 8083025

Claim:
A silencer provided on an exhaust pipe of a vehicle engine, the silencer comprising: an inner cylinder disposed at an intermediate position of the exhaust pipe; a housing that accommodates the inner cylinder and defines an expansion chamber between the inner cylinder and the housing; and a partition cylinder accommodated in the housing and sectioning the expansion chamber into an inner expansion-chamber section at an inner region in a radial direction and an outer expansion-chamber section at an outer region in the radial direction, the outer expansion-chamber section being filled with an acoustic material, the partition cylinder having a group of partition-cylinder small holes through which the inner expansion-chamber section and the outer expansion-chamber section communicate with each other, wherein the inner cylinder has a group of inner-cylinder small holes through which an inside of the inner cylinder communicates with the inner expansion-chamber section, wherein the group of partition-cylinder small holes and the group of inner-cylinder small holes do not overlap each other in an axial direction and are separated from each other by a predetermined distance in the axial direction, and wherein the partition cylinder includes a downstream portion that is adjacent to an outlet of said silencer and has a diameter that is larger than a diameter of a remaining portion of the partition cylinder.