Method for manufacturing concentric double exhaust pipe for internal combustion engine

Abstract

A concentric double exhaust pipe for an internal combustion engine includes an outer pipe 10 and an inner pipe 20. The outer pipe 10 and inner pipe 20 have basal ends fixed to each other. A seal member 30 arranged between the two pipes 10 and 20 enable sliding of distal ends of the outer pipe 10 and the inner pipe 20 during thermal expansion. When manufacturing the concentric double exhaust pipe, the outer pipe 10 is compressed after attaching the seal member 30 between an inner surface of the outer pipe 10 and an outer surface of the inner pipe 20 so as to compress the seal member 30 to a predetermined outer diameter.

1 . A method for manufacturing a concentric double exhaust pipe for an internal combustion engine, the exhaust pipe including an outer pipe and inner pipe having basal ends fixed to each other, with the inner pipe arranged in the outer pipe, and a seal member arranged between the outer pipe and the inner pipe and enabling relative movement of distal ends of the outer pipe and the inner pipe during thermal expansion, the method comprising: 
 compressing the outer pipe after attaching the seal member between an inner surface of the outer pipe and an outer surface of the inner pipe so as to compress the seal member to a predetermined outer diameter.    
   
   
       2 . The method for manufacturing a concentric double exhaust pipe for an internal combustion engine according to  claim 1 , wherein the outer pipe is compressed through a spinning process.  
   
   
       3 . The method for manufacturing a concentric double exhaust pipe for an internal combustion engine according to  claim 1 , wherein the outer pipe is compressed through a pressing process.  
   
   
       4 . The method for manufacturing a concentric double exhaust pipe for an internal combustion engine according to  claim 1 , further comprising: 
 measuring thickness of the seal member when attached to the outer surface of the inner pipe and adjusting compression level of the outer pipe based on the measurement.    
   
   
       5 . The method for manufacturing a concentric double exhaust pipe for an internal combustion engine according to  claim 4 , further comprising: 
 calculating a target diameter, which is a compression target for the outer pipe, based on the outer diameter and thickness of the outer pipe and a target thickness, which is a compression target, for the seal member.    
   
   
       6 . The method for manufacturing a concentric double exhaust pipe for an internal combustion engine according to  claim 1 , wherein the seal member has an outer diameter measured when attached to the outer surface of the inner pipe that is set to be smaller than an inner diameter of the outer pipe.  
   
   
       7 . The method for manufacturing a concentric double exhaust pipe for an internal combustion engine according to  claim 1 , wherein the seal member is attached to the outer surface of the inner pipe in a state in which the seal member is widened in the radial direction.  
   
   
       8 . The method for manufacturing a concentric double exhaust pipe for an internal combustion engine according to  claim 1 , further comprising: 
 fixing a mold inside the inner pipe and pressing a roller against an outer surface of the outer pipe while rotating the outer pipe together with the inner pipe.    
   
   
       9 . The method for manufacturing a concentric double exhaust pipe for an internal combustion engine according to  claim 8 , further comprising: 
 adjusting moving velocity of the roller in the axial direction of the outer pipe and feed amount of the roller in the radial direction of the outer pipe to compress the outer pipe.    
   
   
       10 . The method for manufacturing a concentric double exhaust pipe for an internal combustion engine according to  claim 1 , wherein the seal member is a wire mesh formed from fine metal wires.  
   
   
       11 . The method for manufacturing a concentric double exhaust pipe for an internal combustion engine according to  claim 1 , wherein the outer pipe is formed from a steel metal.  
   
   
       12 . A method for manufacturing a concentric double exhaust pipe for an internal combustion engine, the exhaust pipe including an outer pipe and inner pipe having basal ends fixed to each other, with the inner pipe arranged in the outer pipe, and a seal member arranged between the outer pipe and the inner pipe and enabling relative movement of distal ends of the outer pipe and the inner pipe during thermal expansion, the method comprising: 
 performing a diameter enlargement process on the inner pipe after attaching the seal member between an inner surface of the outer pipe and an outer surface of the inner pipe so as to compress the seal member to a predetermined outer diameter.