Heat exchanger tube

Abstract

A flat tube for a heat exchanger is fabricated from a single sheet of metal material. The sheet of metal material has a first edge and a second edge, which are arranged adjacent to one another between a pair of broad walls of the tube. Flat sections extend from the edges and are disposed against one another. A pair of rounded walls arranged at an end of the tube connect the flat sections to the broad walls, and are joined by a weld bead within a space bounded by the outer surfaces of the rounded walls.

What is claimed is: 
     
         1 . A heat exchanger tube fabricated from a single sheet of metal material, comprising:
 a pair of opposing, spaced apart broad walls defining a tube minor dimension;   a tube inner volume provided between the pair of broad walls;   a first rounded wall bounding the tube inner volume at a first end of the heat exchanger tube to connect the pair of broad walls, an outer surface of the first rounded wall having a radius equal to the tube minor dimension;   a first edge and a second edge of the sheet of metal material arranged adjacent to one another between the pair of broad walls;   a first flat section extending from the first edge of the sheet of metal material and a second flat section extending from the second edge of the sheet of metal material, the first flat section and the second flat section disposed against one another;   a second rounded wall arranged at a second end of the heat exchanger tube opposite the first end to connect the first flat section and a first one of the pair of broad walls, an outer surface of the second rounded wall having a radius equal to half of the tube minor dimension;   a third rounded wall arranged at the second end of the heat exchanger tube to connect the second flat section and a second one of the pair of broad walls, an outer surface of the third rounded wall having a radius equal to half of the tube minor dimension; and   a weld bead joining the second and third rounded walls, the weld bead being arranged within a space bounded by the outer surface of the second rounded wall and the outer surface of the third rounded wall.   
     
     
         2 . The heat exchanger tube of  claim 1 , wherein the first flat section and the second flat section are connected by a braze joint. 
     
     
         3 . The heat exchanger tube of  claim 2 , wherein the first flat section is additionally connected to the first one of the pair of broad walls by a braze joint and wherein the second flat section is additionally connected to the second one of the pair of broad walls by a braze joint. 
     
     
         4 . The heat exchanger tube of  claim 1 , wherein the tube inner volume is bounded at the second end by the first and second edges of the sheet of metal material. 
     
     
         5 . The heat exchanger tube of  claim 1 , wherein the sheet of metal material has a thickness and wherein the tube minor dimension is four times that thickness. 
     
     
         6 . The heat exchanger tube of  claim 1 , wherein the tube inner volume is bounded at the second end by the second and the third rounded walls. 
     
     
         7 . The heat exchanger tube of  claim 1 , wherein the weld bead is disposed entirely to one side of a plane that is tangent to both the outer surface of the second rounded wall and the outer surface of the third rounded wall. 
     
     
         8 . A method of making a heat exchanger tube, comprising:
 feeding a continuous flat sheet of metal material into a tube mill;   hemming opposing edges of the flat sheet of metal material in a first forming station of the tube mill to form first and second rounded ends;   forming the sheet of metal material into a cylindrical shape, thereby bringing the first and second rounded ends into contact with one another, in a second forming station of the tube mill;   creating a weld bead between the first and second rounded ends;   flattening the cylindrical shape in a third forming station of the tube mill; and   separating the heat exchanger tube from the continuous flat sheet of metal material in a cut-off station of the tube mill.   
     
     
         9 . The method of  claim 8 , wherein the step of flattening the cylindrical shape brings the edges of the sheet of metal material into contact with one another. 
     
     
         10 . The method of  claim 9 , further comprising forming braze joints between the edges of the sheet of metal material. 
     
     
         11 . The method of  claim 10 , further comprising forming braze joints between a first one of the original edges of the sheet of metal material and a first broad outer wall of the tube and between a second one of the original edges of the sheet of metal material and a second broad outer wall of the tube. 
     
     
         12 . The method of  claim 8 , wherein the weld bead is created in a welding station of the tube mill, the welding station of the tube mill located immediately downstream of the second forming station within the tube mill. 
     
     
         13 . The method of  claim 8 , further comprising:
 inserting an insert into the heat exchanger tube; and   further flattening the heat exchanger tube after insertion of the insert.   
     
     
         14 . The method of  claim 13 , wherein the step of further flattening the heat exchanger tube occurs by compressing a heat exchanger core into which the heat exchanger tube has been assembled. 
     
     
         15 . A heat exchanger tube obtained by the process of  claim 8 .