Abstract:
A heat exchanger having at least one of side plates embodying a polygonal aperture through the planar base thereof, located at a predetermined position, and at least two corresponding shear-apertures located at the interface between the planar base and a first wall and a second wall of the side plate, each adjacent to the base aperture, providing at least one flexing location to accommodate thermal expansion of the heat exchanger during thermal cycling.

Description:
FIELD 
       [0001]    The present disclosure relates to heat exchangers, and more particularly thermal expansion of heat exchangers. 
       BACKGROUND 
       [0002]    This section provides background information related to the present disclosure which is not necessarily prior art. In the past, it has been known that a core structure of a heat exchanger  5  comprises of a plurality of tubes  7  through the inside of which an internal heat exchange medium passes, a plurality of fins alternately stacked with the tubes  7  and increasing the heat transfer of said heat exchange medium, end tanks  6  to which the two ends of the tubes are connected, and side plates  10  arranged at the outsides in the stacking direction from the end fins arranged at the outermost sides in the stacking direction of the fins and connected to the end tanks  6  (see  FIG. 1 ). 
         [0003]    In this types of core structure of a heat exchanger, the tubes and the corrugated fins are alternately arranged between the two end tanks arranged facing each other across a predetermined distance. The two ends of the two end tanks are bridged by the side plates  10 . Further, the two ends of the tubes  7  and the side plates  10  are inserted into tube holes located in core plates (not shown) of the end tanks  6  and subsequently brazed. 
         [0004]    However, in the aforementioned heat exchanger, when the heat exchange medium begins to pass through the tubes  7 , the difference between the amount of heat expansion of the tubes  7  and the core plates which directly receive the effect of the heat exchange medium and the amount of heat expansion of the side plates  10  which do not directly receive the effect of the heat exchange medium causes thermal stress accompanied with thermal strain in the tubes  7  and the side plates  10 . Further, if thermal stress is repeatedly generated, there is the problem of fatigue breakage in the vicinities of the tube and core plate interface. 
         [0005]    As a countermeasure, there is the art described in U.S. Pat. No. 7,198,095. In this patent, there is a thermal expansion ‘break-off zone’ provided on the side plates. This design enables a predetermined breaking point, adapted to break when subjected to thermally-induced stress caused in the tubes during operation of the heat exchanger. 
         [0006]    However, in this design, the complete breakage of the side plate provides a location for buckling of the corrugated fins and tubes adjacent to the side plates, creating a dimensional error of the core unit assembly. 
         [0007]    U.S. Pat. No. 7,389,810 improves on this, by providing a flexible zone to accommodate thermal expansion, but further requires a cutting process of the base portion during manufacturing, which must be accomplished prior to assembly of the heat exchanger. This cutting step makes post assembly alignment and brazing difficult. 
       SUMMARY 
       [0008]    In light of the above deficiencies in the prior art, an object of the present invention is to provide a heat exchanger able to prevent breakage at the joints of the tubes and the side plates at the core plates, able to be easily produced, and reduced in cost which has side plates enabling stable brazing of the tubes and the fins with the side plates. 
         [0009]    According to a first aspect of the present invention, there is provided a heat exchanger wherein at least one of the side plates  10  has a polygonal aperture through the planar base of the side plate at a predetermined position, and at least two corresponding shear-apertures located at the interface between the planar base and a first wall and a second wall of the side plate, each adjacent to the base aperture. 
         [0010]    Due to this, when brazing the tubes and the fins with the side plates, the rigidity of the side plates is still maintained (flexing is difficult) and the tubes and the fins can be uniformly pressed with the side plates. Because of this, stable brazing of the tubes and the fins with the side plates becomes possible, yet, while still providing a flex-area to allow thermal expansion and contraction of the heat exchanger assembly without breakage of the side plate during thermal cycling. 
         [0011]    According to a second embodiment of the present disclosure, after brazing, at least one location of the side walls proximal the shear aperture is cut. Due to this, even if the side plates thermally expand during use of the heat exchanger, since the rigidity is low, simple expansion and contraction become further enhanced in the longitudinal direction and thermal stress can be reduced. 
         [0012]    Note that the reference numerals of the above parts show the correspondence with specific parts described in the embodiments explained later. 
     
    
     
       DRAWINGS 
         [0013]    The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure. 
           [0014]      FIG. 1  is a side view of a heat exchanger of the present disclosure; 
           [0015]      FIG. 2  is a partial perspective view of a first embodiment depicting a side plate for a heat exchanger of the present disclosure; 
           [0016]      FIG. 3  is a partial bottom planar view of a detailed portion of the side plate of  FIG. 2 ; 
           [0017]      FIG. 4   a  is partial top planar view of a detailed portion of the side plate of  FIG. 2 ; 
           [0018]      FIG. 4   b  is end view of a detailed portion of the side plate of  FIG. 4A ; 
           [0019]      FIG. 5  is a partial perspective view of a second embodiment depicting a side plate for a heat exchanger of the present disclosure; 
           [0020]      FIG. 5   a  is top planar view of the second embodiment prior to the secondary punching operation; and 
           [0021]      FIG. 5   b  is top planar view of the second embodiment during the secondary punching operation. 
       
    
    
       [0022]    Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings. 
       DETAILED DESCRIPTION 
       [0023]    Example embodiments will now be described more fully with reference to the accompanying drawings. The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. It should be understood that throughout the drawings, corresponding reference numerals indicate like or corresponding parts and features. 
         [0024]    Referring now to  FIG. 1 , a standard heat exchanger  5  for use in automobile applications is shown. The heat exchanger  5  is of the tube and fin type, comprising a plurality of tubes  7  interconnected to an end tank  6  at each end through a core plate (not shown). Staggered between each tube is a corrugated fin for increasing heat exchange performance between the fluid traversing the tubes and the air passing through the fins, perpendicular to the longitudinal direction of the tubes. 
         [0025]    The heat exchanger  5  further embodies at least one side plate  10 , in contact with the last row of corrugated fins, which interconnects the end tanks  6  through the core plate, and maintains the structural integrity of the tube and fin assembly during assembly and installation. 
         [0026]    Referring now to  FIGS. 2 and 3 , a first embodiment of the present disclosure will be explained in detail. As illustrated, the side plate  10  of the heat exchanger assembly comprises a generally planar base portion  16 , and generally perpendicular side walls  12  and  14  extending in a stacking direction of the tubes and fins. The planar base portion comprises at least one polygonal base aperture  18 , positioned perpendicular to a longitudinal direction of the side plate spanning approximately the width of the base portion  16 . This aperture as depicted is a diamond shape (rhombus shape), but it should be understood that any similar polygonal shape having similar dimensions would yield similar results, and therefore intended to be within the scope of this application. 
         [0027]    This base aperture  18  can be formed by cutting or drilling, but preferably is formed by a punch. Staggered latitudinal, and straddling longitudinally on either side of the base aperture  18  of the base portion  16 , are two interface apertures  20 ,  22  located at the interface between the base portion  16  and the walls  12  and  14  respectively. These interface apertures  20 ,  22  each define an opening extending partially up the side walls  12  and  14 , and further extending laterally across the base portion a pre determined distance, so as to overlap the base aperture  18  in a longitudinal direction of the side plate  10  a predetermined distance. 
         [0028]    As illustrated in  FIGS. 4   a  and  4   b , these interface apertures  20 ,  22  are formed subsequent to aperture  18 , by a shear punch  15  operating at a  45  degree angle in reference to the planar base portion of the side plate  10 . 
         [0029]    This configuration of interface apertures  20 ,  22  located on either side of base aperture  18  creates flex bridges  26  and  28  in the planar base portion  16 , as well as perpendicular flex portions  25  and  27  in the walls  12  and  14  respectively above adjacent shear apertures  20 ,  22 . 
         [0030]    In operation, these flex bridges  26 ,  28  and flex portions  25 ,  27  provide for areas in the side plate  10  to contract and expand during thermal cycling, in both the latitudinal and longitudinal dimensions of the heat exchanger with reference to the direction of the plurality of pipes, while still maintaining the overall structural integrity of the assembly. 
         [0031]    Referring now to  FIG. 5 , a secondary embodiment of the present invention is shown. In order to increase the thermal flexing of the heat exchanger side plate  10  during thermal cycling, an additional cutting operation is performed as illustrated in  FIGS. 5   a  and  5   b . Preferably this operation is conducted after the side plate is brazed onto the heat exchanger, but it could optionally be conducted prior to assembly. 
         [0032]    As shown in  FIGS. 5   a  and  5   b , the side plate  10  is aligned in a shear punch machine which comprises staggered shear punches  21  and  23 , positioned on opposite sides of the side plate  10 , so as to align with interface apertures  20 ,  22  respectively. The shear punches then operate to sever and partially deflect the wall portions  32 ,  34  located above the interface apertures  20 ,  22  inward, yielding only flex bridges  26 ,  28  as the remaining connection means for maintaining the side plate  10  as a single structure. This embodiment provides greater flexibility in the latitudinal direction during thermal cycling, while still maintaining the overall structural integrity of the assembly. 
         [0033]    The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the invention, and all such modifications are intended to be included within the scope of the invention. 
         [0034]    Example embodiments are provided so that this disclosure will be thorough, and will fully convey the scope to those who are skilled in the art. Numerous specific details are set forth such as examples of specific components, devices, and methods, to provide a thorough understanding of embodiments of the present disclosure. It will be apparent to those skilled in the art that specific details need not be employed, that example embodiments may be embodied in many different forms and that neither should be construed to limit the scope of the disclosure. In some example embodiments, well-known processes, well-known device structures, and well-known technologies are not described in detail. 
         [0035]    Although the terms first, second, third, etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms may be only used to distinguish one element, component, region, layer or section from another region, layer or section. Terms such as “first,” “second,” and other numerical terms when used herein do not imply a sequence or order unless clearly indicated by the context. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the example embodiments.