Abstract:
A heat exchanger and a heat exchanger core are disclosed. The heat exchanger core is formed from a strip of synthetic resin molded into multiple panels which are accordion folded to form the heat exchanger core. One embodiment is a counterflow core in which sides of each panel parallel to the longitudinal axis of the strip are divided to form a closed portion and an open portion. The opposite longitudinal sides are similarly formed but the portions are reversed. The sides of each panel perpendicular to the longitudinal axis of the strip are closed either by a hinge formed in the strip or by panel borders abutting each other. A second embodiment discloses a strip also formed into multiple panels and accordion folded. However, every second hinge has an opening so that when folded, a cross flow core is created. Both cores are mated with appropriately designed molded plastic housings to form effective but simple and economical heat exchangers.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field Of The Invention  
           [0002]    The present invention relates to a heat exchanger and a core thereof and more particularly to an economical heat exchanger and core which are simple, reliable and easy to assemble.  
           [0003]    2. Description Of The Related Art  
           [0004]    Heat exchangers are used in many applications and are made of different materials, most notably metal and plastic. Such heat exchangers are disclosed in U.S. Pat. Nos. 6,119,768, 4,997,031; 4,907,648; 4,874,035; 4,858,685; 4,820,468; 4,738,311; and GB 2158569, and PCT Applications SE82/00393 and GB98/03368. Typically, metal heat exchangers are relatively expensive. Plastic heat exchangers tend to be more economical. Examples of recent plastic heat exchangers are shown in U.S. Pat. Nos. ______ (09/665,462) and ______ (09/664,624). In PCT/GB98/03368 the heat exchanger core is formed of identical sheets of plastic where every other sheet is rotated 90 degrees to construct a cross flow type heat exchanger. As is apparent, there continues to be efforts to create an economical, simply constructed and easily assembled heat exchanger to bring costs down and to enhance operation.  
         BRIEF SUMMARY OF THE INVENTION  
         [0005]    The difficulties encountered in the past have been overcome by the present invention. What is described here is a heat exchanger comprising an outer housing, an elongated strip of synthetic resin material located in the outer housing, the strip having a longitudinal axis. The elongated strip also has longitudinal sides and lateral sides and is divided into a plurality of panels. A plurality of hinges is formed in the elongated strip where each of the plurality of hinges extends generally perpendicular to the longitudinal axis and connecting lateral sides of adjacent panels. Alternate hinges are bendable in opposite directions so that the elongated strip assumes an accordion folded disposition. Each of the plurality of panels is aligned generally parallel to and spaced from adjacent panels of the plurality of panels when folded and the plurality of panels forms first and second passages between adjacent pairs of panels where one panel of each of the adjacent pairs of panels is common to both adjacent pairs. Latitudinal sides of a pair of adjacent panels opposite a hinge connecting them form a closure.  
           [0006]    There are a number of advantages, features and objects achieved with the present invention which are believed not to be available in earlier related devices. For example, one advantage is that the present invention provides an economical heat exchanger and core. Another object of the present invention is to provide an economical heat exchanger and core which is simply constructed and easily assembled. Still another feature of the present invention is to provide an economical heat exchanger and core which may be easily disassembled, cleaned and reassembled.  
           [0007]    A more complete understanding of the present invention and other objects, advantages and features thereof will be gained from a consideration of the following description of the preferred embodiment read in conjunction with the accompanying drawing provided herein.  
       
    
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING  
       [0008]    [0008]FIG. 1 is a plan view of a flat strip of synthetic resin material formed as disclosed herein.  
         [0009]    [0009]FIG. 2 is an enlarged broken sectional view taken along line  2 - 2  of FIG. 1.  
         [0010]    [0010]FIG. 3 is an enlarged broken sectional view taken along line  3 - 3  of FIG. 1.  
         [0011]    [0011]FIG. 4 is an enlarged broken sectional view taken along line  4 - 4  of FIG. 1.  
         [0012]    [0012]FIG. 5 is a front isometric view of a partially folded heat exchanger core made from the flat strip illustrated in FIG. 1.  
         [0013]    [0013]FIG. 6 is a rear isometric view of the partially folded heat exchanger core shown in FIG. 5.  
         [0014]    [0014]FIG. 7 is a downward looking isometric view of the heat exchanger core shown in FIGS. 5 and 6, but in a fully folded position.  
         [0015]    [0015]FIG. 8 is an exploded isometric view of the heat exchanger core shown in FIGS.  5 - 7  installed in a heat exchanger housing.  
         [0016]    [0016]FIG. 9 is a plan view of another embodiment of a flat strip of synthetic resin material formed as disclosed herein.  
         [0017]    [0017]FIG. 10 is a sectional view taken along line  10 - 10  of FIG. 9.  
         [0018]    [0018]FIG. 11 is a sectional view taken along line  11 - 11  of FIG. 9.  
         [0019]    [0019]FIG. 12 is a sectional view taken along line  12 - 12  of FIG. 9.  
         [0020]    [0020]FIG. 13 is an enlarged view taken within the circle  13 - 13  of FIG. 11.  
         [0021]    [0021]FIG. 14 is an enlarged view taken within the circle  14 - 14  of FIG. 11.  
         [0022]    [0022]FIG. 15 is a right side, downward looking isometric view of a partially folded heat exchanger core shown in FIGS.  9 - 14 .  
         [0023]    [0023]FIG. 16 is an enlarged left side, downward looking isometric view of the heat exchanger core shown in FIG. 15.  
         [0024]    [0024]FIG. 17 is an enlarged view of a portion of the heat exchanger core taken within the circle  17 - 17  of FIG. 16.  
         [0025]    [0025]FIG. 18 is an enlarged view of the heat exchanger core taken within the circle  18 - 18  of FIG. 15.  
         [0026]    [0026]FIG. 19 is an isometric view of the heat exchanger core of FIGS.  9 - 18  placed in a housing. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0027]    While the present invention is open to various modifications and alternative constructions, the preferred embodiments shown in the drawing will be described herein in detail. It is understood, however, that there is no intention to limit the invention to the particular forms disclosed. On the contrary, the intention is to cover all modifications, equivalent structures and methods, and alternative constructions falling within the spirit and scope of the invention as expressed in the appended claims.  
         [0028]    The simplicity and economical features of the present invention are apparent by referring to FIGS.  1 - 4 . There is illustrated a portion of a formed elongated strip  10  of synthetic resin material. For purposes of orientation, a longitudinal axis  12  for the strip is illustrated in phantom line. The elongated strip portion is shown divided into four panels  14 ,  16 ,  18 ,  20  with each panel having opposed longitudinal sides and opposed latitudinal sides, such as the longitudinal sides  22 ,  24  of the panel  18  and the latitudinal sides  26 ,  28  of the same panel. Each panel has two longitudinal and two latitudinal sides. It is further to be understood that while only four panels are illustrated, the elongated strip will usually contain far more panels as will be explained hereinbelow. Between adjacent panels is an integral hinge, such as the hinge  30  between the panels  14  and  16 , the hinge  32  between the panels  16  and  18  and the hinge  34  between the panels  18  and  20 . Also, as will be shown in detail below, the hinges are made to fold in alternate directions to achieve an accordion like disposition when the strip is folded at the hinges during assembly.  
         [0029]    The longitudinal sides  22 ,  24  are each divided into first and second generally equal portions. For example, the longitudinal side  22  includes a first portion  40  and a second portion  42 . In a like manner, the longitudinal side  24  includes a first portion  44  and a second portion  46 . As shown more clearly in FIGS. 2 and 3, each portion of the longitudinal sides includes a bent border but in an alternating fashion. For example, the longitudinal side portion  40  has a downward or closed bend whereas the longitudinal side portion  42  has an upward or open bend. The opposite longitudinal side portions of a panel are bent in opposing directions. For example, the longitudinal side portion  44  is bent upwardly or in an open position whereas the longitudinal side portion  46  is bent downwardly or in a closed position. The concept of opened and closed portions will also be explained in more detail below. Each of the latitudinal sides, such as the sides  26 ,  28  has a raised border which will act as a spacer to separate the adjacent panels when the strip is folded. The latitudinal sides of each panel are integrally formed adjacent a hinge except for the end latitudinal sides  50 ,  52  of the end panels  14 ,  20 , respectively of the strip.  
         [0030]    Referring now to FIGS. 5 and 6, the elongated strip  10  is shown enlarged and in a partially folded position where the folded hinges bend in alternate directions, accordion-like. It can now be appreciated that the longitudinal side portions alternately provide openings to form first and second sets of fluid flow passages through the folded stack of panels, the fluid flow passages being generally parallel to the latitudinal sides of the panels. For example, the first portion  44   a  of the longitudinal side  24   a  of the panel  14  is bent downwardly to meet the upwardly slanting second portion  46   b  of the longitudinal side  24   b  of the panel  16 . When these side portions come together, a closure is formed against fluid flow entering or leaving through the left side portion of the space between the panels  14 ,  16  as viewed in FIG. 5. The right side portion of the space, however, formed by the side portion  46   a  and the side portion  44   b  are bent upwardly so as to provide an opening to fluid flow on the right side between the panels  14  and  16 . On the opposite longitudinal side of the panel, the edge portions  40   a  and  42   b  are bent upwardly to form an opening whereas the edge portions  42   a  and  40   b  are bent downwardly to form a closure.  
         [0031]    Referring to the latitudinal sides  28  and  26   a  surrounding the hinge  34 , FIG. 4, it is seen that there are raised borders for the purpose of spacing adjacent panels from one another. This can be seen by way of example between the two panels  18 ,  20 , FIG. 6. It can also now be observed by referring to FIG. 5 that the hinges alternate in the direction of folding from counterclockwise to clockwise to counterclockwise, etc. When the elongated strip is fully folded as shown in FIG. 7, two sets of fluid passages are formed. This is clearly shown in FIG. 6 where there is formed a first set of fluid passages, exemplified by the passage  60  formed between the panels  18  and  20 , and a second set of fluid passages, exemplified by the passage  62  formed between the panel  20  and its adjacent panel  64 . A passage identical to the passage  62  is also formed between the panels  16  and  18  whereas an identical passage to the passage  60  is formed between the panels  14  and  16 . The two types of passages alternate between adjacent pairs of panels where one panel of the adjacent pairs is common to both pairs. Thus, the two pairs of panels  14 ,  16  and  16 ,  18  have the panel  16  in common. It is also noted that because of the alternating design, the set of passages, like the passage  60 , is open on the right side of the stacked panels when viewed from the front (FIG. 5) and is open on the right side when viewed from the rear (FIG. 6). Stated another way, the passages “cross” the panels when moving in a direction generally perpendicular to the longitudinal axis  12  of the strip. In a similar but opposite manner the other set of passages, like the passage  62 , also cross the panel. Nevertheless, most of the flows in the passages are such that it can be said that the core produced is of the counterflow variety.  
         [0032]    It has already been disclosed that alternate portions of the longitudinal sides of the panels are closed and open. Referring now to the latitudinal sides, they are, in all cases, closed. For example, each of the hinges  30 ,  32 ,  34  connect adjacent panels as a solid integral piece. Further, between hinges a closure is formed by abutting raised latitudinal sides, such as the sides  26   b ,  28 , FIGS. 5 and 6. In a similar manner a closure or seal  68 , FIG. 6, is formed along the latitudinal sides of the panels  18  and  20 .  
         [0033]    When the elongated strip is fully folded as shown in FIG. 7, two sets of fluid flow passages are formed which alternate along the stack as exemplified by the fluid flow passages  60 ,  62 . The passages are formed between alternate pairs of panels and by the structure of the individual panels and related hinges. Seals or closures are formed by abutting panels to keep the two sets of fluid passages separate. Thus, a fluid flow entering from the front, right side through the passage  60  is separated from another fluid flow entering from the rear, left side through the passage  62 . This latter fluid flow will exit from the left, front side of the stacked panels. The flow passages are sealed because the hinges are solid material and the contacting portions of opposite latitudinal sides may be pressed together to prevent leakage. Or, an adhesive may be used to seal the contacting portions or heat may be used to cause bonding of these portions. The flow passages are further separated by the panels themselves. It is readily understood that if lower as a function of the desired heat transfer. The same is true of the dimensions of the panels. These may also change depending upon the heat transfer characteristics desired.  
         [0034]    The simplicity and versatility of the present invention is shown by reference to FIGS.  9 - 18 . There is illustrated another embodiment of a heat exchanger core which is similar to the embodiment illustrated in FIGS.  1 - 8  except that the second embodiment is for a cross-flow heat exchanger rather than a counterflow heat exchanger. There is illustrated a portion of an elongated strip  110  of synthetic resin material having a longitudinal axis  112 . The elongated strip is formed into a series of connected or integral panels  114 ,  116 ,  118 ,  120 . Each of the panels includes longitudinal sides and latitudinal sides, such as the longitudinal sides  122 ,  124  and latitudinal sides  126 ,  128  of the panel  118 . Hinges  130 ,  132 ,  134  are formed integral with the panels and are positioned between panels to allow the strip to be alternately folded in an accordion fashion. The longitudinal and latitudinal sides have raised borders so that when folded, each panel is spaced from an adjacent panel whereby fluid flow passages between panels are created.  
         [0035]    The most striking difference between the heat exchanger core embodiment shown in FIG. 1 and that shown in FIG. 9 is that the core in FIG. 9 has a region of every second hinge which is mostly open. When the elongated strip is folded, this opening forms an inlet or outlet for a fluid flow passage. Also, longitudinal sides of the panels either form a closure or an opening. In this manner, two series or sets of fluid flow passages are provided, the passages being at right angles to each other. One set of passages conducts flows parallel to the longitudinal axis  112  whereas the other set of passages conducts flows perpendicular to the first mentioned set and to the longitudinal axis.  
         [0036]    Referring to FIGS.  9 - 16  in more detail, the openings between the panels are seen in more detail. For example, between the panel  114  and the panel  116  the hinge  130  includes a forward portion  130   a  and a rearward portion  130   b  separated by an opening  150 . The hinge  132  extends across the strip of material without any opening. The hinge  134  is also divided between a forward portion  134   a , a rearward portion  134   b  and a central opening  152 . Following the open hinge  134  is a closed hinge  154  which is identical to the hinge  132 . In this fashion, closed and open hinges alternate with each other.  
         [0037]    Referring again to FIG. 16, the raised borders  156 ,  158  are illustrated along the upper and lower longitudinal sides  122 ,  124 , respectively, of the panel  118 . The longitudinal sides of the adjacent panel  120  also include projecting borders  155 ,  157 . When the projecting borders  155 ,  157  of the panel  120  engage or abut the projecting borders  156 ,  158  of the panel  118 , closures are formed longitudinally. However, between the adjacent pair of panels  116 ,  118 , the longitudinal sides do not have raised or abutting borders and thus openings are formed. Referring now to FIGS. 17 and 18, the alternating openings  160 ,  162  in the longitudinal sides between panels is shown alternating with closed or sealed longitudinal sides  161 ,  163  caused by raised or projecting borders, such as the raised borders  164 ,  166 . The latitudinal sides have openings, such as the opening  170 , alternating with closed hinges, such as the hinges  154 ,  172 . As with the earlier embodiment, nesting elements of two panels may also be used to close sides of the panels to fluid flow.  
         [0038]    The cross flow may best be seen by reference to FIGS.  16 - 18  where a fluid flow passage having the opening  170 , parallel to the longitudinal axis, has an inlet, depicted by an inlet arrow  180 , and an outlet, depicted by an outlet arrow  182 . A fluid flow passage having the opening  162  includes an inlet, depicted by the inlet arrow  190 , and an outlet, depicted by the outlet arrow  192 , FIG. 16.  
         [0039]    Referring to FIG. 19, there is illustrated the folded stacked strip  110  forming a core. The core is positioned in a heat exchanger housing  200  having a cover  202 , a first inlet  204 , a first outlet  206 , a second inlet  208  and a second outlet  210 . One comer  212  of the core is sealed against a wall  214  of the housing, an opposing comer  216  of the core is sealed to an opposite wall  218 , a third comer  220  of the core is sealed to a third wall  222  and a fourth comer  224  of the core is connected to a partition  226  which is sealed to a fourth wall  228 . This arrangement also allows for oppositely directed fluid flows if desired.  
         [0040]    In operation, the core is formed from a long strip of PVC material which is formed by any suitable process, such as vacuum forming or embossing, to fold in an accordion-like fashion. The folded core may be used as is and placed in a heat exchanger housing or the abutting borders or edges or surfaces may be bonded and sealed in some fashion such as with an adhesive polymeric cure-in-place compound, a preformed seal system, such as a molded or die-cut gasket or by the use of an RF welder, thermal border or a combination of these or other methods. The heat exchanger housings include two inlets and two outlets which define flow paths to and from the fluid passages formed in the core. In the case of the embodiment shown in FIGS.  1 - 8 , a counterflow heat exchanger is formed whereas with the embodiment shown in FIGS.  9 - 19 , a cross-flow heat exchanger is formed.  
         [0041]    The specification describes in detail two embodiments of the present invention. Other modifications and variations will, under the doctrine of equivalents, come within the scope of the appended claims. For example, dimensional differences for the core, a greater or lesser number of panels in a core, differences in geometries and the like are all considered equivalent structures. Also, fluid flow directions designated first and second may be perpendicular to each other, or parallel to each, and when parallel, they may be in opposite directions or in the same direction. That is, the first and second directions may be generally the same though separated. Further, the fluid in one flow may be a gas such as air while the fluid in the second flow may be a liquid. These are all equivalent. Still other alternatives will also be equivalent as will many new technologies. There is no desire or intention here to limit in any way the application of the doctrine of equivalents.