Heat exchangers comprising winglet tubes, winglet tubes and method for producing same

Abstract

Disclosed is a heat exchanger, in particular for motor vehicles, having a large number of flat tubes which contain indentations (“winglets”) and through which a fluid cooling medium can flow, and having corrugated fins which are associated with these flat tubes and to which environmental air or other media can be applied. In addition, there is disclosed a method for producing flat tubes of this type (“winglet tubes”) and for assembling these flat tubes into heat exchangers.

1 . A method for producing a flat tube for a motor vehicle heat exchanger, wherein the tube has a central portion and end portions, comprising: 
 forming a pattern of indentations on a sheet, in areas that correspond to the central portion and at least one end portion of a tube to be produced;    at least substantially flattening out at least a portion of the raised surface of at least one indentation in the area corresponding to the at least one end portion of the tube, to form an at least substantially flat region on the area of the sheet corresponding to the at least one end region; and    forming the sheet into the shape of a tube having a substantially flat region at at least one end portion.    
   
   
       2 . A method according to  claim 1 , wherein said forming comprises a continuous procedure applied to an endless length of metal sheet, and the method further comprises cutting the tube in an intermediate portion of the substantially flat region, to form a tube having a predetermined length and a substantially flat region at at least one end portion.  
   
   
       3 . A method according to  claim 1 , wherein the indentations comprise winglets.  
   
   
       4 . A method according to  claim 3 , wherein the plurality of indentations comprise a plurality of winglets.  
   
   
       5 . A method according to  claim 1 , wherein the step of forming indentations comprises forming two linear, parallel indentations and wherein the step of forming the metal sheet into a tube comprises forming an hour-glass tube.  
   
   
       6 . A method according to  claim 1 , wherein the step of forming indentations comprises forming a steg.  
   
   
       7 . A tube for a motor vehicle heat exchanger produced by the method according to  claim 1 .  
   
   
       8 . A tube for a motor vehicle heat exchanger produced by the method according to  claim 4 .  
   
   
       9 . A tube for a motor vehicle heat exchanger produced by the method according to  claim 5 .  
   
   
       10 . A tube for a motor vehicle heat exchanger produced by the method according to  claim 6 .  
   
   
       11 . A method for producing a heat exchanger for a motor vehicle, comprising: 
 (a) producing a flat tube by a method according to  claim 1;     (b) inserting the substantially flat end portion of the tube into a header; and    (c) brazing to form a fluid-tight seal at the junction between the flat tube and header.    
   
   
       12 . A method according to  claim 1 , comprising producing a plurality of flat tubes, inserting a plurality of substantially flat ends of tubes into a header, and brazing to form a plurality of fluid-tight seals at the junctions between the flat tubes and the header.  
   
   
       13 . A heat exchanger produced according to the method of  claim 11 .  
   
   
       14 . A motor vehicle comprising a heat exchanger according to  claim 12.