Stacking-type, multi-flow, heat exchangers and methods for manufacturing such heat exchangers

Abstract

A stacking-type, multi-flow, heat exchanger includes heat transfer tubes and outer fins stacked alternatively. Each heat transfer tube is formed by connecting a pair of tube plates, and each heat transfer tube includes a raised portion fixing the pair of tube plates to each other. The raised portions are formed by elongating or raising a portion of the pair of tube plates substantially simultaneously at a position at which a pair of holes, each of which is formed through one tube plate beforehand, are aligned. Complicated steps, such as inserting a raised portion into a hole, are not necessary. The number of types of tube plates also may be reduced. Moreover, the efficiency of assembling a heat transfer tube when fixing a pair of tube plates to each other may be significantly increased.

1 . A stacking-type, multi-flow, heat exchanger comprising a plurality of heat transfer tubes and a plurality of outer fins, which are stacked alternatively, each of said heat transfer tubes comprising a pair of tube plates connected together to form a fluid passage in each of said heat transfer tubes, each of said heat transfer tubes further comprising: 
 raised portions fixing said pair of tube plates to each other, said raised portions being formed by elongating said pair of tube plates substantially simultaneously at a position at which a pair of holes, each of which is formed through one of said pair of tube plates, are aligned.    
   
   
       2 . The stacking-type, multi-flow, heat exchanger of  claim 1 , wherein each of said raised portions comprises a tip portion having an enlarged diameter.  
   
   
       3 . The stacking-type, multi-flow, heat exchanger of  claim 1 , wherein an inner fin is disposed in said fluid passage in each of said heat transfer tubes, said inner fin extending in a longitudinal direction of each of said heat transfer tubes.  
   
   
       4 . The stacking-type, multi-flow, heat exchanger of  claim 3 , wherein said inner fin is a waved fin.  
   
   
       5 . A method for manufacturing a stacking-type, multi-flow, heat exchanger comprising a plurality of heat transfer tubes and a plurality of outer fins, which are stacked alternatively, each of said heat transfer tubes being formed by connecting a pair of tube plates to form a fluid passage in each of said heat transfer tubes, said method comprising the steps of: 
 forming a hole through each of said pair of tube plates;    positioning said pair of tube plates, so that said holes of said pair of tube plates are aligned; and    elongating said pair of tube plates substantially simultaneously at a position at which said holes are aligned for fixing said pair of tube plates to each other.    
   
   
       6 . The method of  claim 5 , further comprising the steps of enlarging diameters of tip portions of raised portions, formed by said step of elongating.