Muffler

Abstract

Provided is a muffler having a double pipe portion formed therein in which an end portion of a first tubular member is inserted into a second tubular member from an end portion thereof. A leading end portion of the second tubular member is joined to an outer periphery of the first tubular member. A portion that forms the double pipe portion of the second tubular member comprises a first portion located closer to an end of the first tubular member, and a second portion that is located closer to an end of the second tubular member and that has an enlarged diameter compared with the first portion. A resonance chamber is formed between the first tubular member and the second portion. A communication path that allows communication between an exhaust flow path and the resonance chamber is formed between the first tubular member and the first portion.

1 . A muffler comprising:
 a first tubular member that forms an exhaust flow path of an internal combustion engine; and   a second tubular member that is connected to the first tubular member and forms the exhaust flow path together with the first tubular member,   wherein a double pipe portion is formed in which an end portion of the first tubular member is inserted into the second tubular member from an end portion thereof,   wherein a leading end portion of the second tubular member is joined to an outer periphery of the first tubular member,   wherein a portion that forms the double pipe portion of the second tubular member comprises a first portion located closer to an end of the first tubular member, and a second portion that is located closer to an end of the second tubular member and that has an enlarged diameter compared with the first portion,   wherein a resonance chamber is formed between the first tubular member and the second portion,   wherein a communication path that allows communication between the exhaust flow path and the resonance chamber is formed between the first tubular member and the first portion, and   wherein a Helmholtz type resonant system is formed by the resonance chamber and the communication path.   
     
     
         2 . The muffler according to  claim 1 ,
 wherein a spacer that inhibits contact between the first tubular member and the second tubular member is provided in the communication path, and   wherein the spacer is arranged so as to secure an air passage on an outer circumference of the first tubular member so that the communication path is not blocked.   
     
     
         3 . The muffler according to  claim 1 ,
 wherein each of the first tubular member and the second tubular member is formed as a single part.   
     
     
         4 . The muffler according to  claim 1 ,
 wherein the second tubular member is connected to an end portion in the downstream side of the first tubular member.   
     
     
         5 . The muffler according to  claim 4 ,
 wherein the first tubular member is a member comprising a reduced diameter portion, which is a portion formed by reducing in diameter a portion having a specified length from a downstream-side end of a circular pipe part, and a body portion, which is a non-reduced-diameter portion,   wherein the second tubular member is a member comprising an enlarged diameter portion, which is a portion formed by enlarging in diameter a portion having a specified length from an upstream-side end of a circular pipe part, and a body portion, which is a non-enlarged-diameter portion,   wherein a downstream-side end portion including an entirety of the reduced diameter portion and part of the body portion of the first tubular member is inserted into the second tubular member,   wherein the resonance chamber, which is a dead-end space that communicates with the exhaust flow path, is formed between the body portion of the first tubular member and the enlarged diameter portion of the second tubular member, and   wherein the communication path is formed between the reduced diameter portion of the first tubular member and the body portion of the second tubular member, the communication path being a space, a cross-sectional area of which orthogonal to an axial direction is smaller than that of the resonance chamber and which allows communication between the exhaust flow path and the resonance chamber.   
     
     
         6 . The muffler according to  claim 1 ,
 wherein the second portion is shaped such that the second portion is gradually increased in outside diameter from a position a length L 2  apart from the end toward the end, becomes largest in outside diameter at a position a length L 3  apart from the end (L 3 <L 2 ), and is gradually decreased in outside diameter from a position a length L 4  apart from the end (L 4 <L 3 ) toward the end.