Dual pipe exhaust manifold

Abstract

A dual pipe exhaust manifold includes an inner pipe, an outer pipe and a plurality of spacers. The inner pipe includes a plurality of branch pipes and a plurality of collector pipes. The collector pipes are slidably connected to each other. One end of each of the branch pipe is fixed to a flange section configured and arranged to be attached to a cylinder head of an engine, and the other end of each of the branch pipe is slidably connected to a corresponding one of the collector pipes so that each of the collector pipes is connected to a plural number of the branch pipes. The outer pipe covers a circumference of the inner pipe. The spacers are disposed between the outer pipe and the inner pipe to form a gap therebetween.

1 . A dual pipe exhaust manifold comprising:
 an inner pipe including a plurality of branch pipes and a plurality of collector pipes, the collector pipes being slidably connected to each other, one end of each of the branch pipes being fixed to a flange section configured and arranged to be attached to a cylinder head of an engine, and the other end of each of the branch pipes being slidably connected to a corresponding one of the collector pipes so that each of the collector pipes is connected to a plural number of the branch pipes;   an outer pipe covering a circumference of the inner pipe; and   a plurality of spacers disposed between the outer pipe and the inner pipe to form a gap therebetween.   
     
     
         2 . The dual pipe exhaust manifold according to  claim 1 , wherein
 the collector pipes are fitted to each other so as to be slidable with respect to each other in a direction parallel to the flange section.   
     
     
         3 . The dual pipe exhaust manifold according to  claim 1 , wherein
 each of the branch pipes is fitted in the corresponding one of the collector pipes from one of a direction parallel to the flange section and a direction perpendicular to the flange section.   
     
     
         4 . The dual pipe exhaust manifold according to  claim 1 , wherein
 each of the collector pipes is an integrally press-formed pipe in which opposing end portions are disposed on an opposite side from a surface to be hit by exhaust gas that has flowed into the collector pipe.   
     
     
         5 . The dual pipe exhaust manifold according to  claim 2 , wherein
 at least two of the branch pipes are respectively fitted in corresponding ones of the collector pipes in a direction parallel to the flange section and in directions opposed to each other.   
     
     
         6 . The dual pipe exhaust manifold according to  claim 1 , wherein
 a tip end of each of the collector pipes and the branch pipes which is slidably inserted into a corresponding one of the collector pipes and the branch pipes is extended in a radial direction toward an inner circumferential surface of the corresponding one of the collector pipes and the branch pipes and folded back to reduce leakage of exhaust gas.