Abstract:
A portable cooler having one or more ice sheets including built-in refrigerant cubes. The cooler comprises an outer fabric shell and one or more sets of spaced apart refrigerant cubes encapsulated in plastic to form ice sheets that are attached to the interior walls of the cooler. The walls of the cooler may also include one or more layers of thermal insulation. The ice sheets provide a visually pleasing appearance to the inside of the cooler suggestive of cooling effects. The ice sheets may be retained along the walls of the cooler by seams sewn along the lanes passing between the refrigerant cubes, by being retained in pockets formed by sidewall liners or by being secured into chambers defined by the cooler&#39;s outer walls and a plastic insert fitted into the cooler. The cooler may include a hinged top and bottom that can be folded flat for allowing the cooler to assume a compact configuration during storage or freezing of the refrigerant cubes.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
   This application claims the benefit of U.S. patent application Ser. No. 10/661,044 filed on Sep. 13, 2003, which is incorporated herein by reference. 
   BACKGROUND OF THE INVENTION 
   The present invention relates to portable coolers for foodstuffs, beverages and other articles such as biological tissue specimens and temperature sensitive chemicals and pharmaceuticals. More specifically the present invention relates to portable coolers that provide refrigerant as a built-in part of the cooler itself and to wall constructions for coolers that allow sheets of refrigerant cubes to be incorporated into the structure of the cooler itself. 
   Many types of portable coolers and ice chests exist that are designed for allowing food and beverages to be kept chilled for limited periods. Some coolers have a hard shell of molded plastic that gives them a rigid construction. Other types of coolers feature exterior layers of tough but pliable fabric that are sewn together to form a more flexible containment structure. Many portable coolers are used simply to provide thermal insulation and keep their contents cool by protecting against rapid heating. Unfortunately, under warm conditions these types of coolers can at most keep their contents cool for short periods of time on the order of two or three hours. Most coolers are used with blocks or cubes of ice or frozen gel solution that are usually encapsulated in plastic containers or in small polyvinyl packets. These containers or packets of freezable material are separate and removable from the coolers and are usually purchased as separate products. Prior to use the containers or packets are placed in a freezer until they become frozen solid. When placed in a cooler these frozen materials actively cool and chill the contents of the cooler as they absorb heat energy corresponding to their heat of fusion and low starting temperature. This approach can provide more long lasting effects and can even cool down beverages and food which start at room temperature. However, the containers and packets of freezable material can be inconvenient and awkward to handle and position within the cooler and can take up a lot of otherwise usable space within the interior of the cooler if they are not designed to compactly fit within the cooler. 
   Portable coolers are designed to be simply and easily manufactured while providing the greatest amount of cooling possible and at the same time to be as convenient to use and as visually appealing to the consumer as possible. Some existing patents exemplify current designs and illustrate the prior art pertinent to the present invention. 
   U.S. Pat. No. 4,324,111 to Edwards entitled Freezing Gel Containment Structure and Method provides an active cooling structure composed of adjacent plastic tubes of encapsulated freezing gel that form rigid panels for surrounding a bottle or the like. The tubes may be encased in decorative covers but the tubes and covers are not formed into closed containment structures. 
   U.S. Pat. No. 4,183,226 to Moore entitled Refrigerated Beverage Holder similarly describes a cylindrical sleeve of reusable refrigerant in the form of ice packs shown as elongated sealed sections of plastic. The sealed sections or bars of encapsulated refrigerant are disposed within the beverage can holder along the interior of its outer insulated wall in the space between the beverage can and the holder. The beverage can holder may include inner walls defining an annular section for containing the refrigerant. 
   U.S. Pat. No. 5,570,588 to Lowe entitled Freezable Insert Cooler provides a rigid molded plastic cooler body having a rectangular shape and including hollow perimeter sidewalls. A freezable gel pack insert is positioned within one or more of the hollow perimeter sidewalls and is removable so that it can be conveniently frozen apart from the cooler. The gel pack is described as being constructed of heat sealed webs that may include integral hinges. 
   U.S. Pat. No. 4,311,022 to Hall entitled Foldable Ice Pack provides a ice pack having a large number of separate refrigerant containing compartments within a multiple layered wall assembly of foldable plastic sheet material. The outer walls of the assembly are intended to help control the accumulation of condensation. The inner walls are heat sealed between adjacent compartments to define the compartments and form webbing strips between them. Among other things, the ice pack is described as being used with ice chests and lunch boxes. 
   U.S. Pat. No. 4,700,706 to Munch entitled Cold and Warm Pack For Physiotherapy And The Like describes a sleeve composed of two layers of flexible foil that are bonded together. One layer of foil is planar while the other defines cups and flanged edges. The cups are filled with special temperature storage filling material so as to function as cold or warm packs for medical use. 
   U.S. Pat. No. 2,602,302 to Poux entitled combination Ice and Hot Pack provides an elongated rectangular body having a series of sealed spaced-apart compartments containing water or some other refrigerant fluid. The body member is described as being composed of thin rubber or plastic sheeting which allows the member to be readily flexed. The article may be prepared for use by being placed in a freezer and may be employed for therapeutic or for the heating and cooling of other articles such as foods. 
   U.S. Pat. No. 4,931,333 to Henry entitled Thermal Packaging Assembly describes the use of capsules having a flexible outer skin and containing a thermal controlling agent such as a refrigerant. The capsules have sloping, rounded outer surfaces and may be efficiently packed in large numbers around items to be maintained at a controlled temperature. The capsules may also be provided in a continuous sheet in bubble pack form for being wrapped around items as packing. 
   SUMMARY OF THE INVENTION 
   The present invention comprises a portable ice cooler for refrigerating food, beverages and other articles having an ice sheet of encapsulated cubes of refrigerant built into and secured along one or more of its interior walls. In the preferred embodiment the cooler includes a soft shell of flexible fabric constructed and arranged to form a container also having a lid through which access may be gained to the interior of the container. The ice sheet is deployed along one or more of the inside walls of the container. The cooler may also include one or more layers of thermal insulation extending between the outer fabric shell and the ice sheet. The ice sheet comprises a backing layer and a top layer between which the spaced apart refrigerant cubes are encapsulated in rows and columns separated by lanes. The ice sheet may be attached to the container by plurality of seams running along the lanes between said refrigerant cubes formed by threads sewn through said ice sheet for attaching the ice sheet to the container&#39;s outer shell. Alternatively, The ice sheet may be attached to the container by dividing the ice sheet into segments and using a transparent lining to form corresponding pockets in which the segments may be secured along one or more of the interior walls of the container. In the preferred embodiment the container has a rectangular cross section but have different shapes such as being cylindrical. The cooler may have a hinged top and a hinged bottom that can be pivoted or swung open for allowing access to the interior of the cooler or pivoted flat for allowing the cooler to assume a compact configuration during storage and freezing of the refrigerant cubes in a freezer compartment. The cooler may have one or more zippered pockets secured along the outside of the fabric shell and its lid may include a zipper for operating as a closure. 
   In another aspect of the invention a wall construction for a portable ice cooler is provided including a layer of flexible fabric constructed and arranged to serve as a generally planar foundation member and an ice sheet of refrigerant cubes that is attached to the fabric layer. The ice sheet preferably comprises a backing layer and a top layer between which the spaced apart refrigerant cubes are encapsulated in rows and columns. 
   In a further aspect of the invention a portable cooler is provided having a plastic insert which functions as a liner. The insert cooperates with outer shell of the cooler to form one or more narrow chambers in which ice sheets having refrigerant cubes may removeably reside along the interior walls of the cooler. 
   It is an object of the present invention to provide a portable ice cooler for refrigerating food, beverages and other articles that is convenient to use and that integrally incorporates refrigerant into its structure. 
   It is another object of the present invention to provide a portable ice cooler for refrigerating food, beverages and other articles in which the heat of fusion of the refrigerant can be used to actively cool the contents of the cooler. 
   It is a further object of the present invention to provide a portable ice cooler for refrigerating food, beverages and other articles that provides refrigerant in the form of a sheet of visually pleasing spaced apart ice-like cubes of refrigerant. 
   It is yet another object of the present invention to provide a portable ice cooler for refrigerating food, beverages and other articles in the form of a container which is lined along one or more of its walls with one or more sheets of encapsulated cubes of refrigerant. 
   It is also an object of the present invention to provide a wall construction for a cooler that allows the refrigerant to be efficiently incorporated into the structure of the cooler. 
   It is also another object of the present invention to provide a wall construction for a cooler which provides a visually pleasing display of spaced-apart ice-like refrigerant cubes which suggest a cooling function. 
   It is a yet further object of the present invention to provide a portable cooler in which a sheet of refrigerant cubes may be removeably secured along the interior walls of the cooler. 
   It is another object of the present invention to provide a portable cooler that can assume a flat and compact configuration for convenient storage and for taking up as little space as possible in a freezer during freezing of the refrigerant cubes. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention may be better understood with reference to the following drawings in which like reference numbers are intended to refer to like elements. 
       FIG. 1  provides a perspective view of a diagrammatic illustration of an ice sheet including sections or groups of multiple refrigerant cubes in accordance with the present invention. 
       FIG. 2  provides an enlarged overhead plan view of an ice sheet shown in  FIG. 1  illustrating spacing of the refrigerant cubes in accordance with the present invention. 
       FIG. 3  provides a cross-sectional view along lines  3 - 3  of  FIG. 2  of an ice sheet showing the details of the construction of a sheet of refrigerant cubes in accordance with the present invention. 
       FIG. 4  provides a perspective view of a typical portable cooler having a flexible fabric outer shell and more particularly of the outside of a closed rectangular shaped cooler. 
       FIG. 5  provides a perspective view of the portable cooler of  FIG. 4  with its top open and more particularly of the inside of an open cooler showing ice sheets deployed along the inside sidewalls of the cooler in accordance with the present invention. 
       FIG. 6  provides a lateral cross-sectional view along lines  6 - 6  of  FIG. 4  of the portable cooler illustrating the deployment of ice sheets along the inside walls of the cooler accordance with the present invention. 
       FIG. 7  provides an enlarged cross-sectional view of the typical wall for a portable cooler in accordance with the present invention illustrating the construction of the wall. 
       FIG. 8  provides an enlarged cross-sectional view of another typical wall construction for a portable cooler in accordance with the present invention illustrating an alternative construction for the wall. 
       FIG. 9  provides a perspective view of a portable cooler having a cylindrical configuration and more particularly of the outside of a closed cylindrically shaped cooler. 
       FIG. 10  provides a perspective view of the portable cooler of  FIG. 9  with its top open and more particularly of the inside of an open cylindrical cooler showing ice sheets deployed along the inside sidewall of the cooler in accordance with the present invention. 
       FIG. 11  provides a longitudinal cross-sectional view along lines  11 - 11  of  FIG. 9  of the cylindrical portable cooler illustrating the deployment of ice sheets along the inside walls of the cooler in accordance with the present invention. 
       FIG. 12  provides a lateral cross-sectional view along lines  12 - 12  of  FIG. 9  of the cylindrical portable cooler further illustrating the deployment of ice sheets and the construction of a cooler sidewall in accordance with the present invention. 
       FIG. 13  provides a lateral cross-sectional view of an alternative design for a portable cooler in accordance with the present invention in which a plastic insert is used to hold the ice sheets in position along the sidewalls of the cooler. 
       FIG. 14  provides a perspective view of an alternate embodiment of the portable cooler of the present invention having a both a top and bottom that may be opened and having its top open showing ice sheets deployed along the inside sidewalls of the cooler which are open to view. 
       FIG. 15  provides a perspective view of the alternative embodiment of the portable cooler of the present invention shown in of  FIG. 14  with its main body folded flat and with both its top and bottom pivoted fully open. 
       FIG. 16  provides a cross-sectional view along lines  16 - 16  of  FIG. 15  of the alternative embodiment of the portable cooler of the present invention shown in of  FIG. 14  collapsed into a compact configuration with its main body folded flat and with both its top and bottom pivoted flat and extending inside its folded sidewalls. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Referring now to  FIGS. 1 and 2 , an ice sheet  10  is shown including a flexible but generally planar backing layer  12  and including a large number of spaced apart refrigerant cubes  16  disposed along its upper surface  18 . The refrigerant cubes  16  are preferably grouped in sections  20  each of which have four cubes. The refrigerant cubes are deployed in rows  22  and columns  24  separated by lanes  26  and  28  running across the sheet  10  from its perimeter edges  15 . The sectional lanes  28  running between the sections  20  of refrigerant cubes  16  are preferably somewhat wider than the other lanes between the cubes. The refrigerant cubes  16  in  FIG. 2  are each shown as having a logo (the letters MF) stamped or embossed on their top surfaces. 
   Referring now to  FIG. 3 , a top layer  14  is formed into cup-shaped sections  30  and heated-sealed at joints  32  along the lanes  26  and  28  to the upper surface  18  of backing layer  12  so as to form small ice cube-like sealed compartments  34  in which the refrigerant is contained. The compartments  34  are generally cubic or prismatic in shape with rounded upper corners  36 . The compartments  34  define the shapes and positions for the refrigerant cubes  16 . The backing layer  12  and top layer  14  are preferably comprised of thin polyethylene films that that can be easily heat-sealed together. A very thin layer of heat reflective metal foil  25  is adhered to the far side of the backing layer opposite the cubes  16 . The refrigerant preferably comprises clear water but may comprise a freezing gel solution having a somewhat lower freezing point than 32 degrees Fahrenheit. After being frozen the refrigerant cubes  16  are capable of absorbing heat energy equivalent to their heat of fusion as they melt and thereby providing a chilling effect on surrounding materials. 
   Referring now to  FIGS. 4 and 5 , a portable cooler  40  is shown having a flexible outer shell  42  of durable fabric such as nylon. The cooler  40  includes four sidewalls  44 , a bottom  46  and a lid  48  that define the rectangular structure of the container formed by the cooler  40 . The cooler also includes a carrying handle  52  and a zipper  53  which extends along the top edges of the sidewalls  44  as well as along the outer edge of the lid  48 . The zipper  53  acts as a closure to the cooler  40 . When the zipper  53  is open the lid  48  can be tilted upward as shown in  FIG. 5  so that the interior of the cooler  40  can be conveniently inspected and accessed. Ice sheets  50  including multiple refrigerant cubes  16  are attached to the interior sidewalls  44  of the cooler  40  and effectively built into the structure of the cooler  40 . In preparation for use the cooler  40  is placed in a freezer or the freezer compartment of a refrigerator so that refrigerant cubes  16  can be frozen. After the refrigerant cubes  16  are solidified the cooler  40  may be taken out for use. The refrigerant cubes  16  provide active cooling or chilling of the contents of the cooler  40  during use. 
   Referring now to  FIG. 6 , the sidewalls  44 , bottom  46  and lid  48  of the cooler  40  each include an outer fabric shell  42 , a layer  54  of thermal insulation such as polyurethane foam, and a inner lining  56  of washable plastic as shown with respect to the sidewalls  44 . The sidewalls  44 , bottom  46  and lid  48  are sewn and secured together at seams  58 . The sidewalls  44  include the ice sheets  50  which are deployed along the interior surfaces  45  of the sidewalls  44 . Segments of the ice sheets  50  are held within closed pockets  60  formed by a set of sidewall liners  62  which are secured to the sidewalls  44  by being sewn to the sidewall layers at seams  65  along their perimeter edges  67  and along the spaces  69  in between the individual ice sheets  50 . The sidewall liners  62  are preferably transparent so that the refrigerant cubes are visible and the visually pleasing cooling appearance of the inside of the cooler afforded by the cubes is maintained. 
   Referring now to  FIG. 7 , the cooler wall  75  is constructed of several layers including a fabric shell  72 , an insulation layer  74 , an interior plastic lining  76 , ice sheets  70  and wall liner  78 . The fabric shell  72  is preferably a tough and durable layer of nylon although many different types of fabrics could be employed and provides protection, structural integrity, and mechanical support. The insulation layer  74  is preferably made of polyurethane foam although many different types of thermal insulation could be employed and reduces the flow of heat into the interior of the cooler thereby helping to maintain the cooler colder for a longer period. The insulation layer  74  may also assist in providing support and structural integrity. The plastic lining  76  seals off the inside of the cooler and helps preserve cleanliness. The lining  76  may include an optional heat reflective metallic coating as further added thermal insulation. The ice sheets  70  include a backing layer  71  and a top layer  73  of polyethylene film formed to define compartments for refrigerant cubes  86 . The wall liner  78  is attached to the interior lining  76  and insulation layer  74  at the seams  82  and defines the pockets  80 . The seams  82  are comprised of thread sewn through the wall liner  78 , the interior lining  76  and the insulation layer  74 . The pockets hold the ice sheets  70  against the lining  76  thereby forming an interior wall for an ice cooler featuring active cooling of the interior contents of the cooler by the refrigerant cubes  86  of the ice sheets  70 . 
   Referring now to  FIG. 8 , the alternative cooler wall  95  is constructed of several layers including a fabric shell  92 , a thermal insulation layer  94 , an interior plastic lining  96 , and ice sheet  90 . The shell  92 , insulation layer  94  and lining  96  are similar to the shell  72 , insulation layer  74  and lining  76  of the cooler wall  75 . The ice sheet  90  includes a backing layer  91  composed of a very thin sheet of heat reflective metallic foil and a top layer  93  of thin polyethylene film formed to define ice cube like compartments for the refrigerant cubes  106 . In this case the ice sheet  90  is secured directly onto the lining  96  by the seams  102  which comprise thread sewn through the ice sheet  90 , the lining  96  and the insulation layer  94  along the sectional lanes  104  of the ice sheet  90 . 
   Referring now to  FIGS. 9 and 10 , the portable cooler  110  is cylindrically shaped and has a flexible outer shell  112  of durable fabric such as nylon. The cooler  110  also includes a cylindrically shaped unitary sidewall  114 , a bottom  116  and a lid  118  that define the cylindrical structure of the container formed by the cooler  110 . The cooler is adapted for chilling and storing beverage cans, bottles and the like. The cooler also includes a storage pocket  122  for miscellaneous items and two zippers  123  and  125  which extend along the top and bottom edges of the sidewall  114  as well as along the outer edge of the lid  118  and bottom  116 . The zippers  123  and  125  function as a closures to the main compartment of the cooler  110 . When the zipper  123  is open the lid  118  can be tilted upward as shown in  FIG. 10  so that the interior of the cooler  110  can be conveniently accessed. Ice sheets  120  including multiple refrigerant cubes  136  are attached to the interior sidewalls  114  of the cooler  110  and built into the structure of the cooler  110 . In preparation for use the cooler  110  is placed in a freezer or the freezer compartment of a refrigerator so that refrigerant cubes  136  can be frozen. After the refrigerant cubes  136  are solidified the cooler  110  may be taken out for use. The refrigerant cubes  136  provide active cooling or chilling of beverage cans placed in the cooler  110  during use. 
   Referring now to  FIG. 11 , the sidewall  114 , bottom  116  and lid  118  of the cooler  110  include an outer fabric shell  112 , a layer of thermal insulation  124  such as polyurethane foam, and an inner lining  126  of washable plastic. The sidewall  114 , bottom  116  and lid  118  are sewn and secured together at seams  128 . The sidewall  114  includes the ice sheets  120  which are deployed along the interior surfaces  115  of the sidewall. The ice sheets  120  are held within pockets  130  formed by a set of sidewall liner  132  which are secured to the sidewall  114  by the seams  134  sewn to the sidewall layers along their perimeter edges  135  and along the spaces  137  in between the ice sheets  120 . The sidewall liner  132  is preferably transparent so that the refrigerant cubes  136  are visible and the visually pleasing cooling appearance of the inside of the cooler afforded by the cubes is maintained. 
   Referring now to  FIG. 12 , the cooler sidewall  114  is constructed of several layers including a tough fabric shell  112 , a thermal insulation layer  124 , an inner plastic lining  126 , ice sheets  120  and sidewall liners  132 . The ice sheets  120  include a backing layer  121  and a top layer  123  of polyethylene film formed to define compartments for the refrigerant cubes  136 . The sidewall liners  132  are attached to the interior lining  126  and insulation layer  124  at the seams  134  and define the pockets  130 . The seams  134  comprise thread sewn through the sidewall liners  130 , the interior lining  116  and the insulation layer  114 . The pockets  130  hold the ice sheets  120  against the lining  126  thereby forming an interior wall for an ice cooler featuring active cooling of the contents of the cooler  110  by the refrigerant cubes  136  of the ice sheets  120 . 
   Referring now to  FIG. 13 , the cooler  140  includes sidewalls  144 , a bottom  146  and a lid  148  that define the rectangular structure of the cooler. The sidewalls  144 , bottom  146  and lid  148  are sewn and secured together at seams  158 . The lid  148  tilts up and pivots from the hinge  149  when the cooler  140  is open. The sidewalls  144 , bottom  146 , and lid  148  are constructed so as to each include an exterior fabric shell  152 , a thermal insulation layer  154 , and an interior plastic lining  156 . The cooler  140  also includes plastic insert  160  that may be composed of a pliable sheet material but is preferably comprised of a hard plastic providing a rigid structure. The insert  160  has a rectangular shape conforming to the inside structure of the cooler  140  but is also slightly spaced apart from the sidewalls  144 . The insert  160  retains the ice sheets  170  along the interior sides of the cooler against the lining  156  in the narrow cavity or chamber  165  along the sidewalls  144  between the insert  160  and the lining  156 . The insert  160  is preferably transparent so that the refrigerant cubes  166  are visible and provide a visually pleasing appearance that is suggestive of cooling. The insert  160  is removable so that it can be cleaned and, more importantly, so that the ice sheets  170  can in turn also be removed and conveniently placed in a freezer so they can be solidified in preparation for the cooler  140  being used and reused. After the refrigerant cubes  166  are solidified they may be replaced into the cooler  140 . The refrigerant cubes  166  then provide active cooling or chilling of the surrounding contents placed in the cooler  140  during use. 
   Referring now to  FIG. 14 , a portable cooler  180  is shown having a flexible outer shell  182  of durable fabric such as nylon. The cooler  180  includes four separate sidewalls  184   a - d  connected at corners  185   a - d , a top  186  and a bottom  188  that define the basic prismatic shape of the cooler  180 . Ice sheets  196  including multiple refrigerant cubes  198  are attached to the interior sides of the sidewalls  184   a - d  of the cooler and are effectively built into the structure of the cooler  180 . The cooler  180  also includes a carrying handle  190  of fabric attached to opposite sidewalls  184   b  and  184   d  of the cooler. Zippers  192  and  194  extend along the outer perimeter edges of the top  186  and of the bottom  188  and the corresponding top and bottom edges of the three sidewalls  184   a ,  184   b  and  184   d . In preparation for use the cooler  180  is placed in a freezer or the freezer compartment of a refrigerator so that refrigerant cubes  198  can be frozen. After the refrigerant cubes  198  are solidified the cooler  180  may be taken out for use. During use the refrigerant cubes  198  provide active cooling or chilling of the food, beverage and other articles placed within the cooler  180 . 
   The zipper  194  along the bottom  188  is ordinary kept closed when the cooler  180  is in use thereby allowing the bottom  188  to remain fixed in place and sealing off the inside of the cooler  180 . The zipper  192  along the top  186  may be opened to allow the top to operate as a lid that can be tilted upward as shown so that the interior of the cooler  180  can be inspected and the articles inside can be conveniently accessed. When the top  186  is tilted down and closed the zipper  192  can be closed sealing off the inside of the cooler  180 . The top  186  and bottom  188  are connected to the top edge  202  and bottom edge  204  of one of the sidewall  184   c  by thin flaps  206  and  208  of flexible fabric that function as simple hinges allowing the top  186  and bottom  188  to pivot with respect to the sidewall  184   c  to which they are connected. In use the top  186  may alternatively pivot upward to allow for access to the inside of the cooler  180 , outward at right angles so the zipper  192  can be closed and the cooler can be sealed or parallel with the sidewall  184   c  so that it lies flat. In use the bottom  188  may alternatively pivot outward at right angles so the zipper  194  can be closed and the cooler can be sealed or parallel with the sidewall  184   c  so that it lies flat. The sidewalls  184   a - d  are connected at corners  185   a - d  by flexible seams  195   a - d  that allow the sidewalls  184   a - d  to pivot or with respect to each other and allow the structure formed by the sidewalls  184   a - d  to also fold flat. 
   Referring now to  FIG. 15 , the cooler  180  is shown with the zippers  192  and  194  opened and the top  186  and bottom  188  pivoted fully outward from and forming one hundred eighty degree angles with the sidewall  184   c  of the cooler  180 . The main body  200  of the cooler  180  formed by the sidewalls  184   a - d  is folded at the seams  195   a - d  so that the inside right angles of the two corners  185   b  and  185   d  go to zero degrees and the inside right angles of the two corners  185   a  and  185   c  go to one hundred eighty degrees. The cooler  180  thereby takes on a flat configuration with the sidewalls  184   a - b  resting on top of the sidewalls  184   c - d  which constitutes one of the compact forms that the cooler can assume for storage and especially for placement in a freezer compartment during cooling and freezing of the refrigerant cubes. 
   Referring now to  FIG. 16 , the cooler  180  is shown in cross-section with the zippers  192  and  194  opened the main body of the cooler  180  formed by the sidewalls  184   a - d  again folded (as in  FIG. 15 ) at the seams  195   a - d  so that the body of the cooler assumes a flat configuration. However, in this case the cooler  180  is shown with the top  186  and bottom  188  pivoted inward toward each other parallel with the sidewall  184   c  of the cooler  180 . The top  186  and bottom  188  are sandwiched in between the folded sidewalls  184   a - d . In effect the cooler  180  is collapsed into a flat configuration which is as compact as possible for storage and especially for placement in a freezer compartment. 
   Although the present invention has been described with reference to the specific embodiments described above, it should be recognized that changes may be made in the form and details of the invention as described without departing from spirit of the invention or the scope of the claims.