Heat exchanger and tube therefor

Abstract

Heat exchanger tube ( 2 ), typically for an automotive heat exchanger, includes a core ( 6 ), external boundary surface ( 7 ) and internal boundary surface ( 5 ). The external boundary surface ( 7 ) includes zones devoid of material having melting point lower than the melting point of the core ( 6 ) and the internal boundary surface ( 5 ) includes material having a lower melting point than the core ( 6 ). Additionally or alternatively the external boundary surface ( 7 ) my include a layer of corrosion protection material and/or cathodic protection material.

1 . A heat exchange tube having a tube wall including a core, an external boundary surface, and an internal boundary surface, the tube comprising a strip or sheet formed to define a plurality of flow paths and an intermediate seam comprising material of the tube wall, wherein: 
 a) along its extent the external boundary surface of the tube wall is, or includes substantial zones, substantially devoid of material having a lower melting point than the core layer, (either as a cladding boundary layer or as material ingressing into the core); and,    b) the tube wall has one or more zones of the internal boundary surface which includes material having a lower melting point than the core layer (either as a cladding boundary layer or as material ingressing into the core layer).    
     
     
         2 . A heat exchange tube according to  claim 1 , for use in a brazed aluminium heat exchanger, wherein the heat exchange tube comprises at least a core aluminium alloy.  
     
     
         3 . A heat exchange tube according to  claim 1  or  claim 2 , wherein the lower melting point material comprises an aluminium alloy.  
     
     
         4 . A heat exchange tube according to any preceding claim, wherein the lower melting alloy comprises an Aluminium-Silicon alloy (typically Aluminium-Silicon hypo-eutectic alloy).  
     
     
         5 . A heat exchange tube according to any preceding claim including an external boundary layer of corrosion protection material and/or cathodic protection material.  
     
     
         6 . A heat exchange tube according to any preceding claim comprising a core aluminium alloy of high strength.  
     
     
         7 . A heat exchange tube according to  claim 6  comprising a core aluminium alloy having magnesium substantially at or above 0.05% Mg.  
     
     
         8 . A heat exchange tube according to any preceding claim of folded or roll-form construction.  
     
     
         9 . A heat exchange tube according to any preceding claim comprising a strip or sheet formed to define a plurality of flow-paths and a longitudinally running seam, the seam comprising material of the tube wall, the tube wall having an internal boundary layer or surface comprising or having one or more zones of a lower melting point material than the core wall material.  
     
     
         10 . A heat exchange tube according to any preceding claim, wherein the longitudinally running seam is positioned intermediate and separating adjacently running flow-paths.  
     
     
         11 . A heat exchange tube having a tube wall including a core, an external boundary surface, and an internal boundary surface, wherein the tube includes an external boundary layer of corrosion protection material and/or cathodic protection material, and along its extent the external boundary surface of the tube wall is, or includes substantial zones, substantially devoid of material having a lower melting point than the core layer, (either as a cladding boundary layer or as material ingressing into the core).  
     
     
         12 . A heat exchange tube according to  claim 11 , wherein the tube wall has one or more zones of the internal boundary surface which includes material having a lower melting point than the core layer (either as a cladding boundary layer or as material ingressing into the core layer).  
     
     
         13 . A heat exchange tube according to  claim 11  or  claim 12 , for use in a brazed aluminium heat exchanger, wherein the heat exchange tube comprises at least a core aluminium alloy.  
     
     
         14 . A heat exchange tube according to  claim 12  or  claim 13 , wherein the lower melting point material comprises an aluminium alloy.  
     
     
         15 . A heat exchange tube according to any of  claims 12  to  24 , wherein the lower melting alloy comprises an Aluminium-Silicon alloy (typically Aluminium-Silicon hypo-eutectic alloy).  
     
     
         16 . A heat exchange tube according to any of  claims 11  to  15  comprising a core aluminium alloy of high strength.  
     
     
         17 . A heat exchange tube according to  claim 16  comprising a core aluminium alloy having magnesium substantially at or above 0.05% Mg.  
     
     
         18 . A heat exchange tube according to any of  claims 11  to  17  comprising a strip or sheet formed to define a plurality of flow paths and an intermediate seam comprising material of the tube wall.  
     
     
         19 . A heat exchange tube according to any of  claims 11  to  18  comprising a strip or sheet formed to define a plurality of flow-paths and a longitudinally running seam, the seam comprising material of the tube wall, the tube wall having an internal boundary layer or surface comprising or having one or more zones of a lower melting point material than the core wall material.  
     
     
         20 . A heat exchange tube according to  claim 19 , wherein the longitudinally running seam is positioned intermediate and separating adjacently running flow-paths.  
     
     
         21 . A vehicle heat exchanger including a heat exchange tube according to any preceding claim.  
     
     
         22 . A vehicle heat exchanger according to  claim 21  comprising a tube plate having an aperture through which the tube extends, the tube plate having a layer or surface zone of material having a lower melting point than the core layer of the tube plate and tube.  
     
     
         23 . A vehicle heat exchanger according to  claim 21  or  claim 22  comprising a heat dissipation fin arrangement contiguous with the outer wall of the tube, the fin arrangement including a layer or surface including zones of material having a lower melting point than the core material of the fin.  
     
     
         24 . A method of forming a heat exchange tube comprising deforming strip or sheet material including a core layer and a clad layer of lower melting point material than the core material, the deforming of the strip or sheet material being such as to form tube wall portions and a longitudinally running seam defining respective flow-paths in side by side relationship, the tube wall portions having the clad layer of lower melting point material on the internal, flow-path, side of the tube.