Abstract:
A one-piece header tank includes side edges that are overlapped and brazed together to form a joint positioned within the interior of the tank. The tank also includes an integrally formed mounting flange that may be fabricated without jeopardizing the leak integrity of the tank.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The subject invention relates to a one-piece aluminum heat exchanger tank and a method for fabricating such a tank. 
   2. Description of the Related Art 
   Various heat exchanger tanks exist in the art that are formed from a single sheet of metallic material. These one-piece tanks are typically fabricated by rolling an aluminum-clad sheet into a structure having integrally formed sidewalls and then joining two opposed side edges of the walls together along a common joint. The resulting tank is then connected to a core subassembly using conventional nuts and gasket seals in combination with discrete mounting brackets that must be positioned on the tank before the tank is connected to the core. 
   An example of a one-piece aluminum tank which utilizes separate mounting brackets for mounting the tank to a radiator core is disclosed in U.S. Pat. No. 6,167,953 (“Kobayashi et al.”). The Kobayashi et al., tank features a cylindrical body formed by brazing opposed end edges of an aluminum sheet together to form a joint that extends along the length of the tank. Specifically, one of the end edges of the joint overlaps the other on the exterior surface of the tank. 
   Although forming a single, overlapping joint on the exterior of the Kobayashi et al., tank arguably reduces the number of steps required to fabricate the tank, it does nothing to minimize the space occupied by the tank once it has been connected to a core subassembly. It also creates a rough, marred exterior surface which is so uneven that it renders the tank unuseable. Furthermore, the process of connecting the tank to the core is complicated by the use of the discrete mounting brackets. Each bracket must be separately brazed to the exterior of the tank before the tank can be attached to the core. Given the recent attention focused on creating an aluminum radiator that eliminates the header crimp area between the core and tanks, the marred surface created by overlapping the mounting brackets and exterior joint of the Kobayashi et al., invention fails to provide a suitable solution for minimizing the space occupied by a one-piece header tank. 
   Although Kobayashi et al., and other references specifically disclose aluminum tanks having brazed joints and which are mounted onto cores using separate brackets, the references fail to provide any type of connecting joints that are strong, yet result in a tank having a space-saving and smooth exterior surface. The references also do not disclose a tank featuring such a joint in combination with an integrally-formed bracket or rail for use in connecting the tank to a core. 
   BRIEF SUMMARY OF THE INVENTION AND ADVANTAGES 
   The invention provides a heat exchanger tank formed from a single sheet of clad material. The sheet extends through a rectangular cross-section and defines a tube wall with tube holes extending therethrough. A parallel joint wall is spaced from the tube wall. Spaced parallel sidewalls interconnect the joint and tube walls to define a chamber and opposed open ends. The joint wall has an integrally formed tab that extends therefrom into the chamber. A first of the sidewalls is disposed in sealing engagement with the outside of the tab to enclose the tab within the chamber. 
   The subject invention also provides a method of fabricating a heat exchanger tank. The method includes the step of forming a single sheet of material with a cladding on at least one surface thereof to define a tank extending through a rectangular cross-section and having a tube wall, a parallel joint wall spaced from the tube wall, and spaced parallel sidewalls interconnecting the joint and tube walls to define a chamber having opposed open ends. An additional step is forming an integral tab extending from the joint wall into the chamber. A first of the sidewalls is disposed into engagement with the exterior of the tab to enclose the tab within the chamber, and brazing the first sidewall to the tab. 
   Accordingly, the subject invention overcomes the limitations of the related art by providing a one-piece heat exchanger tank specifically designed to minimize the exterior surface area occupied by the tank after it has been installed on a radiator core. This is achieved by providing a smooth exterior surface created by joining the opposed side edges of the tank in a manner that positions the overlapped edges inside the chamber of the tank, and by incorporating an integrally-formed mounting bracket on the tank without jeopardizing the leak integrity of the tank. 

   
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
     Other advantages of the present invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein: 
       FIG. 1  is a perspective view of a heat exchanger tank according to one embodiment of the present invention and showing end caps; 
       FIG. 2  is an end view of the tank of  FIG. 1 ; 
       FIG. 3  is an enlarged view of the tank shown in  FIG. 2  illustrating the interior braze joint; 
       FIG. 4  is a perspective view of a tank according to  FIG. 1  prior to forming holes, slots or recessed areas on the flange thereof, 
       FIG. 5  is an exploded end view of the tank of  FIG. 1  illustrating a method of forming the tank; 
       FIG. 6  is a perspective view of a heat exchanger tank according to an alternative embodiment of the present invention; 
       FIG. 7  is a perspective view of yet another embodiment of a tank but prior to forming holes, slots or recessed areas on the flange thereof; 
       FIG. 8  is an end view of the tank shown in  FIG. 7 ; and 
       FIG. 9  is an enlarged view of the tank shown in  FIGS. 6 ,  7  and  8  illustrating the exterior braze joint. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Referring to the Figures, wherein like numerals indicate like or corresponding parts throughout the several views, a heat exchanger tank for a cooling system is shown generally at  10  in  FIG. 1 , and at  110  in  FIG. 6 . The tank is formed from a single sheet of material having a cladding  12  on at least one surface thereof. The sheet material shown in the Figures is aluminum sheet material with 4000 series braze on the exterior surface thereof. The sheet extends through a rectangular cross-section to define a tube wall  14  and a parallel joint wall  16  spaced therefrom. Spaced parallel sidewalls  18  interconnect the joint wall  16  and tube wall  14  to define a chamber  20  and opposed open ends  22 ,  24  for permitting fluid flow through the tank  10 . The tube wall  14  includes tube holes  25  through which elongate tubes  26  are received. Each of the tubes  26  defines a passage  28  which extends through the tube  26  to permit fluid flow into the chamber  20 . End caps  30 ,  32 , are positioned for being sealingly engaged with the open ends  22 ,  24  of the tank. 
   Each tank also includes a tab  34  integrally formed with the joint wall  16 . The tab  34  extends into the chamber  20 . A first sidewall  36  of the sidewalls  18  is disposed in sealing engagement with the outside of the tab  34  and encloses the tab  34  within the chamber  20 . In particular, the first sidewall  36  includes an interior joint surface  38  positioned within the chamber  20 . The tab  34  includes an exterior surface  40  with the cladding  12  thereon. The cladding  12  seals the exterior surface  40  into engagement with the joint surface  38  to define an internal braze joint  42  within the chamber  20 . 
   The first sidewall  36  extends above the joint wall  16  and the tab  34  to define a mounting flange  44 . The flange  44  includes a plurality of holes  46  for receiving complementary fasteners therethrough for mounting the tank  10  on the cooling system. The flange  44  has a peripheral edge  48  from which spaced slots  50  extend toward the tab  34 . Like the holes  46 , the slots  50  are used to mount the tank  10  to structure of the cooling system. Recessed areas  52 ,  54  extend from the peripheral edge  48  toward each of the ends  22 ,  24  of the tank for positioning the flange  44  in closely-conforming relation to the cooling system. 
   A heat exchanger tank according to another embodiment of the invention is shown generally at  110  in  FIG. 6 . With the exception of the flange, the tank  110  includes the same components and is formed from the same materials as the tank  10 . 
   The flange  44  of the tank  110  is formed from a double thickness of the sheet material to define primary and reinforcing walls  114  and  116 . The reinforcing wall  116  overlaps the primary wall  114  on the interior thereof and extends transversely over the joint wall  16  on the exterior thereof The cladding  12  on the joint wall  16  seals the reinforcing wall  116  into engagement the joint wall  16  to define an exterior braze joint  118 . A U-shaped fold  120  integrally joins the reinforcing wall  116  with the primary wall  114 . 
   Other than extending through a double thickness of sheet material rather than a single thickness, the holes  122 , slots  124  and recessed areas  126 ,  128  on the tank  110  are identical to the respective holes  46 , slots  50  and recessed areas  52 ,  54  of the tank  10 . Furthermore, other than extending across the double thickness of the sheet material, the peripheral edge  130  from which the slots  124  extend is identical to the peripheral edge  48  of the tank  10 . 
   The subject invention also includes a method of fabricating a heat exchanger tank. The method includes the steps of forming a single sheet of material having a cladding  12  on at least one surface thereof to define a tank  10  extending through a rectangular cross-section and having a tube wall  14  with a parallel joint wall  16  spaced from the tube wall  14 . Spaced parallel sidewalls  18  interconnect the joint and tube walls  16  and  14  to define a chamber  20  having opposed open ends  22 ,  24 . The joint wall  16  and tube wall  14  are interconnected by forming an integral tab  34  that extends from the joint wall  14  into the chamber  20 , and a first sidewall  36  of the sidewalls  18  is disposed into engagement with the exterior of the tab  34  to enclose the tab  34  within the chamber  20 . The first sidewall  36  is then brazed to the tab  34 . 
   The method is further defined as extending the first sidewall  36  upwardly above the joint wall  14  and the tab  34  to project outwardly from the joint wall  14  to define a flange  44 . Still another step is extending holes  46  through the flange  44  for receiving fasteners therethrough to mount the tank  10  on the cooling system. Spaced slots  50  are also formed on the flange  44  and extend from a peripheral edge  48  thereof toward the tab  34  for connecting the tank  10  to the cooling system. In addition, the method includes the step of forming a recessed area  52 ,  54  on each end of the flange  44  that extends from the peripheral edge  44  thereof toward an adjacent end  22 ,  24  of the tank  10 . 
   The method continues in an alternative way by doubling the sheet defining the flange  44  to further define a primary wall  114  and a reinforcing wall  116 . The method is further defined by forming a U-shaped fold  120  which integrally joins the primary wall  114  and reinforcing wall  116 . The method also includes the step of overlapping the primary wall  114  and the joint wall  16  with the reinforcing wall  116 . The reinforcing wall  116  is then brazed to the primary wall  114  and the joint wall  16 . 
   A final step is sealing end caps  30 ,  32  with the open ends  22 ,  24  on each of the tanks  10 , and  110 . 
   Obviously, many modifications and variations of the present invention are possible in light of the teachings set forth above. The invention may be practiced other than as specifically described within the scope of the claims. Furthermore, the foregoing description of the preferred embodiment of the invention and the best mode for practicing the invention are provided for the purpose of illustration only and not for the purpose of limitation—the invention being defined by the claims.