Abstract:
A fintube includes a body having a first fin, a second fin and a tube section. A first overlap fold is provided between the first fin and the tube section. The first overlap fold includes an open groove. A second overlap fold is provided between the second fin and the tube section. A seam includes a second overlap fold received and held in the groove of the first overlap fold. Methods for making a fintube are also disclosed.

Description:
[0001]    This patent application claims the benefit of U.S. Provisional Patent Application Ser. No. 61/463,156 filed on Feb. 14, 2011. 
     
    
     TECHNICAL FIELD 
       [0002]    This document relates generally to the solar energy field, and more particularly, to a one-piece fintube solar heating element. 
       BACKGROUND SECTION 
       [0003]    Fintubes for use as heat exchange elements, such as heating elements in solar energy systems including passive water heating systems, are known in the art. Fintubes generally include a tube for circulating a fluid for purposes of heat exchange and one or more fins for either absorbing heat from or dissipating heat into the environment. In solar water heating systems, the fins absorb heat from incident sunlight and that heat is then transfered from the fins to the tube and then from the tube to the fluid circulating in the tube. One such fintube is manufactured and sold by Thermafin Holding, LLC of Jacksonville, Fla. 
         [0004]    Disclosed herein is a fintube with a unique and simple structure. The fintube has a one-piece construction and incorporates a seam structure (1) that may be relatively easily produced, (2) that provides a long and reliable service life without leaking and (3) that allows for excellent heat exchange between the fins and the tube through which the heat exchange fluid is being circulated. In addition, two methods are disclosed for making the fintube. Advantageously, these methods can be performed utilizing relatively simple forming equipment such as a press brake available in smaller shops around the country. 
       SUMMARY SECTION 
       [0005]    A fintube comprises a body including a first fin, a second fin and a tube section. A first overlap fold is provided between the first fin and the tube section. The first overlap fold includes an open groove. A second overlap fold is provided between the second fin and the tube section. The fintube also has a seam including the second overlap fold received and held in the groove of the first overlap fold. 
         [0006]    More specifically describing the fintube, the body is made from a single continuous sheet of material. That material may be selected from a group consisting of metal, aluminum and copper. The first overlap fold is four layers of material thick. In one embodiment the second overlap fold is two layers of material thick and the seam is six layers of material thick. In another embodiment the second overlap fold is four layers of material thick and the seam is eight layers of material thick. In either embodiment the seam extends continuously along a longitudinal axis of the body. This seam may be sealed in any appropriate manner. 
         [0007]    In accordance with an additional aspect, a method is provided for forming a fintube from a single sheet of material. In a first embodiment, the method steps include: (a) forming a first overlap fold in the sheet material where the first overlap fold includes an open groove, (b) partially forming a tube and erecting a first fin, (c) forming a second overlap fold, (d) partially forming the tube and erecting a second fin and (e) inserting the second overlap fold into the groove so as to form a seam and complete forming of the tube. 
         [0008]    In a second embodiment, the method of forming a fintube from a single sheet of material includes the steps of: (a) forming the sheet into a u-shape, (b) forming a first overlap fold on a first leg of the u-shaped sheet and forming a second overlap fold on a second leg of the u-shaped sheet, (c) doubling over the first and second overlap folds so as to form a first open groove in the first overlap fold and a second open groove in the second overlap fold, and (d) engaging the first and second overlap folds to form a seam while simultaneously erecting the first and second fins and forming a tube. Either method also further includes the sealing of the seam. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]    The accompanying drawings incorporated herein and forming a part of the specification, illustrate several aspects of the fintube and its method of production and together with the description serve to explain certain principles of the fintube. In the drawings: 
           [0010]      FIG. 1  is a perspective view illustrating the fintube; 
           [0011]      FIGS. 2A-2I  illustrate step-by-step a first method for making the fintube; 
           [0012]      FIGS. 3A-3F  illustrate step-by-step a second method for making the fintube. 
       
    
    
       [0013]    Reference will now be made in detail to the present preferred embodiments of the fintube, examples of which are illustrated in the accompanying drawings. 
       DETAILED DESCRIPTION 
       [0014]    Reference is now made to  FIG. 1  illustrating a fintube  10  including a body  12 . The body  12  includes a first fin  14 , a second fin  16  and a tube section  18 . The body  12  is formed from a single sheet of material such as metal, aluminum or copper. The first fin  14 , the second fin  16  and the tube section  18  are all joined together at a seam  20  that runs continuously along the length of the longitudinal axis L of the fintube body  12 . 
         [0015]    The fintube  10  may be utilized as a heat exchange element in, for example, a solar water heater. In which a fluid is circulated through the tube section  18  for purposes of heat exchange. The first and second fins  14 ,  16  are positioned and directed or aligned so as to receive incident sunlight. That sunlight heats the fins  14 ,  16  which transfer heat through the seam  20  through the tube section  18  into the fluid being circulated through that section. 
         [0016]    The fintube  10  may be utilized as a solar heating element in, for example, a passive solar water heater as said forth and described in U.S. Pat. No. 4,505,262 the full disclosure of which is incorporated herein by reference. 
         [0017]    The fintube  10  may be made or manufactured in accordance with a method illustrated in  FIGS. 2A-2I . As illustrated in  FIGS. 2A-2I , the fintube  10  may be formed from a single sheet  22  of material. As illustrated in  FIGS. 2A-2C , a first overlap fold  24  is formed in the sheet material  22 . The first overlap fold includes an open groove  26 . The first overlap fold  24  and open groove  26  are made by folding the first fin  14  over the portion  18  of the sheet material that will eventually form the tube section  18  (see  FIG. 2A ). That initial fold is then doubled over (see action arrows in  FIG. 2B ) and then folded back open (see action arrows in  FIG. 2C ) in order to form the open groove  26 . 
         [0018]    This step is then followed by the partial forming of the tube section  18  and the erecting of the first fin  14  (see particularly  FIGS. 2D and 2E ). Next is the forming of a second overlap fold  28  (see  FIG. 2F ). This is done by folding the second fin  16  so as to overlap a portion of the tube section  18  and then forming a 90° bend (see also  FIG. 2G ). This is then followed by partially folding the tube section  18  and erecting a second fin  16  (see particularly  FIG. 2H ). Next is the step of inserting the second overlap fold  28  into the open groove  26  of the first overlap fold  24  so as to form the seam  20  and complete the forming of the tube section  18  (See  FIG. 2I ). 
         [0019]    The forming steps may be completed by any appropriate means including, for example, a press break or roll former. The seam  20  is also sealed in accordance with any appropriate process including, for example, riveting, cold welding or soldering. In accordance with the first method illustrated in  FIGS. 2A-2I , the resulting fintube  10  includes a first overlap fold  24  that is four layers of material thick, a second overlap fold  28  that is two layers of material thick and a seam  20  that is six layers of material thick. 
         [0020]    A second method for making the fintube  10  is illustrated in  FIGS. 3A-3F . As illustrated in  FIG. 3A , the sheet material  22  is first formed into a u-shape. This is followed by forming a first overlap fold  24  on the first leg  30  of the u-shaped sheet  22  and forming the second overlap fold  28  on the second leg  32  of the u-shaped sheet. See  FIG. 3B . Next is the doubling over of the first and second overlap folds  24 ,  28  so as to form a first open groove  34  in the first overlap fold  24  and a second open groove  36  in the second overlap fold  28  (see  FIG. 3C ). 
         [0021]    This is then followed by the step of engaging the first and second overlap folds  24 ,  28  and first and second grooves  34 ,  36  to form the seam  20  while simultaneously erecting the first and second fins  14 ,  16  and forming the completed tube section  18 . (See  FIGS. 3D and 3E ). 
         [0022]    In accordance with this second method, the first overlap fold  24  is four layers of material thick, the second overlap fold  28  is four layers of material thick and the seam  20  is eight layers of material thick (see particularly  FIG. 3E ). 
         [0023]    As with the first method, the second method illustrated in  FIGS. 3A-3F  may be performed using, for example, a press break or roll former. Further the sealing of the seam  20  may be completed in accordance with any appropriate process including, but not limited to, riveting, soldering and cold welding. 
         [0024]    In accordance with yet another method, one completes the step noted above to go from the structure illustrated in  FIG. 3A  to the structure illustrated in  FIG. 3B . Next one continues to form the tube section  18  until the fins  14 ,  16  one erected and the fins and the overlap folds  24 ,  28  all lie in the same plane. Thus, one goes directly from  FIG. 3B  to  FIG. 3F . The resulting seam  20  of four layers of material may then be rivoted and soldered to seal the seam. 
         [0025]    The foregoing description of preferred embodiments of the fintube and the method of making the same have been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the fintube and methods to the precise form disclosed. Obvious modifications or variations are possible in light of the above teachings. The embodiments were chosen and described to provide the best illustration of the principles of the fintube and its method of production and its practical application to thereby enable one of ordinary skill in the art to utilize the fintube and method of production in various embodiments and with various modifications as are suited to the particular use contemplated. All such modifications and variations are within the scope of the claims in this document when interpreted in accordance with the breadth to which they are fairly, legally and equitably entitled. The drawings and preferred embodiments do not and are not intended to limit the ordinary meaning of the claims in their fair and broad interpretation in any way.