Flat pipe comprising a return bend section and a heat exchanger constructed therewith

Abstract

The invention related to a flat tube ( 1 ) comprising a return bend section ( 3 ), inside of which the flat tube ( 1 ) is bent back in such a manner that both planar tube sections ( 2 a, 2 b ) thereof, which are connect to the return bend section, extend in a longitudinal direction with opposite flow-through directions ( 4 a, 4 b ) and with longitudinal axes ( 5 a, 5 b ) that are offset with regard to one another at least in the transverse direction (y). The invention provides that the return bend section ( 3 ) is formed in such a manner that a main bending axis (A) extends parallel to the flat tube to be plane and at a predeterminable angle to the tube longitudinal extension, whereby the flat tube plane is determined by the longitudinal and width extension of the flat tube ( 1 ).

1 . A flat tube with a return bend section ( 3 ), in which the flat tube ( 1 ) is bent around in such a way that its two planar tube sections ( 2   a,    2   b ) adjoining it run in the longitudinal direction with opposite throughflow directions ( 4   a,    4   b ) and with longitudinal axes ( 5   a,    5   b ) offset relative to one another at least in the transverse direction (y), characterized in that the return bend section ( 3 ) is formed in such a way that a main bend axis (A) runs parallel to the flat tube plane and at a predeterminable angle with respect to the tube longitudinal extent, the flat tube plane being determined by the extent of the flat tube ( 1 ) in terms of length and of width.  
   
   
       2 . The flat tube as claimed in  claim 1 , further characterized in that the predeterminable angle is 90°.  
   
   
       3 . The flat tube as claimed in  claim 1 , further characterized in that the flat tube ( 1 ) is displaced by the amount of a distance (s), parallel to the tube extent, in the flat tube plane in the region of the return bend section ( 3 ).  
   
   
       4 . The flat tube as claimed in  claim 1 , characterized in that the tube sections ( 2   a,    2   b ) merge into the return bend section ( 3 ) at a predeterminable angle (α).  
   
   
       5 . The flat tube as claimed in either  claim 1 , characterized in that the angle (a) and/or the distance (s) are/is achieved by means of at least one bending operation about at least one bend axis (B) which runs perpendicularly with respect to the flat tube plane.  
   
   
       6 . The flat tube as claimed in  claim 5 , further characterized in that the displacement of the flat tube ( 1 ) is achieved by means of two bending operations about two bend axes (B 1 , B 2 ) which are carried out before or after the main bending operation about the first bend axis (A), the first bend axis (A) running in the middle of an offset region (U).  
   
   
       7 . The flat tube as claimed in  claim 1 , further characterized in that the two planar tube sections ( 2   a,    2   b ) adjoining the return bend section ( 3 ) are arranged, with a spacing (d), perpendicularly to the stacked direction (z) in planes parallel to one another.  
   
   
       8 . The flat tube as claimed in  claim 1 , further characterized in that, in a further forming step, the return bend section ( 3 ) is formed in such a way that the two tube legs ( 2   a,    2   b ) lie next to one another and parallel, with the spacing (d), in the same plane.  
   
   
       9 . The flat tube as claimed in  claim 7 , further characterized in that the return bend section ( 3 ) is formed symmetrically or asymmetrically.  
   
   
       10 . The flat tube as claimed in  claim 1 , characterized in that the spacing (d) in the transverse direction (y) is between 0.2 mm and 20 mm.  
   
   
       11 . The flat tube as claimed in one of the preceding claims  claim 1 , characterized in that, by means of the return bend section ( 3 ), an air-facing side of the flat tube section ( 2   a ) becomes an air-facing side of the flat tube section ( 2   b ) and a side of the flat tube section ( 2   a ) facing away from the air becomes a side of the flat tube section ( 2   b ) facing away from the air.  
   
   
       12 . The flat tube as claimed in  claim 1 , characterized in that, by means of the return bend section ( 3 ), a tube underside of the tube section ( 2   a ) becomes the tube top side of the tube section ( 2   b ) and a tube top side of the tube section ( 2   a ) becomes the tube underside of the tube section ( 2   b ).  
   
   
       13 . A flat tube heat exchanger for a motor vehicle air conditioning system, with 
 a tube block ( 9 ) having one or more flat tubes ( 1 ) as claimed in  claim 1 , which are stacked one above the other in a stack direction (z).    
   
   
       14 . The flat tube heat exchanger as claimed in  claim 13 , characterized in that collecting ducts ( 7 ) which run along the stack direction (z) and into which the flat tubes ( 1 ) issue in each case at one end ( 6 ) are arranged laterally on the tube block ( 9 ).  
   
   
       15 . The flat tube heat exchanger as claimed in  claim 13 , characterized in that at least one of the two tube sections ( 2   a,    2   b ) connected to one another via the return bend section ( 3 ) forms a tube serpentine ( 12 ) wound in the stack direction (z).  
   
   
       16 . The flat tube heat exchanger as claimed in  claim 13 , characterized in that the two flat tube ends ( 6 ) lie on the same or on opposite sides, and at least one of the two tube ends ( 6   a,    6   b ) is twisted at an angle of between 0° and 90°.  
   
   
       17 . A gas cooler with a flat tube heat exchanger ( 10 ) as claimed in  claim 13 .  
   
   
       18 . An evaporator with a flat tube heat exchanger ( 10 ) as claimed in  claim 13.