Exhaust member

Abstract

An exhaust member having two or more exhaust ports separated by a partition wall extending between an inner wall of a tubular portion, wherein said partition wall has the minimum thickness A in a range within ½ of the length of said partition wall from its longitudinal middle point as a center, when viewed in an arbitrary transverse cross section of said tubular portion (including an opening end surface) having said partition wall; wherein said partition wall becomes gradually wider outside said range; and wherein each cuter surface of said partition wall exists in a region sandwiched by (a) an inner line comprising a parallel line H 1, H 2 separate from the longitudinal centerline of said partition wall by a distance of A/2, and an arc R 1, R 2 tangentially connected to said parallel line H 1, H 2 and said inner wall and having a radius r 1, r 2, wherein both r 1 and r 2 are ⅓×A or more, meeting r 1 +r 2 =1.9A, and (b) outer line comprising a parallel line H 3, H 4 separate from the longitudinal centerline of said partition wall by a distance of 3/2×A, and an arc R 3, R 4 tangentially connected to said parallel line H 3, H 4 and said inner wall and having a radius r 3, r 4, wherein both r 3 and r 4 are ⅓×A or more, meeting r 3 +r 4 =4A.

1 . An exhaust member having two or more exhaust ports separated by a partition wall extending between an inner wall of a tubular portion, wherein said partition wall has the minimum thickness A in a range within ½ of the length of said partition wall from its longitudinal middle point as a center, when viewed in an arbitrary transverse cross section of said tubular portion (including an opening end surface) having said partition wall, and wherein each outer surface of said partition wall exists in a region sandwiched by ( a ) an inner line comprising a parallel line H 1 , H 2  separate from a longitudinal centerline of said partition wall by a distance of A/ 2 , and an arc R 1 , R 2  tangentially connected to said parallel line H 1 , H 2  and said inner wall and having a radius r 1 , r 2 , wherein both r 1  and r 2  are ⅓×A or more, meeting r 1 +r 2 =1.9A, and ( b ) an outer line comprising a parallel line H 3 , H 4  separate from the longitudinal centerline of said partition wall by a distance of 3/2×A, and an arc R 3 , R 4  tangentially connected to said parallel line H 3 , H 4  and said inner wall and having a radius r 3 , r 4 , wherein both r 3  and r 4  are ⅓×A or more, meeting r 3 +r 4 =4A. 
   
   
       2 . The exhaust member according to  claim 1 , wherein radii r 1 , r 2  of said arcs R 1 , R 2  meet the condition of r 1 +r 2 =2.5A. 
   
   
       3 . The exhaust member according to  claim 1 , wherein the minimum thickness A of said partition wall is 2-10 mm, and wherein each outer surface of said partition wall is tangentially connected to said inner wall with an arc having a radius of 2-13 mm in an arbitrary transverse cross section of said tubular portion. 
   
   
       4 . The exhaust member according to  claim 2 , wherein the minimum thickness A of said partition wall is 2-10 mm, and wherein each outer surface of said partition wall is tangentially connected to said inner wall with an arc having a radius of 2-13 mm in an arbitrary transverse cross section of said tubular portion.