Abstract:
An evaporator device and method of making the device. The evaporator device comprises a one-piece metallic body, which is preferably aluminum or an alloy thereof, with a refrigerant tube embedded therein. The metallic body further includes horizontal fins and vertical partitions protruding from at least one surface that define an array of ice forming cells. The one-piece metallic body is formed by a die casting process that eliminates the conventional assembly steps of separate evaporator pans, refrigerant tube pieces, vertical partitions horizontal fins and other parts.

Description:
RELATED APPLICATION  
       [0001]     This application claims the benefit of U.S. Provisional Patent Application Ser. No. 60/528,227, filed on Dec. 9, 2003, the entire contents of which are incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION  
       [0002]     This invention relates to an evaporator device for an ice machine that has a small number of parts and an improved thermal transfer between a circulating refrigerant and an ice-forming surface. This invention also relates to a method for making the evaporator device.  
       BACKGROUND OF THE INVENTION  
       [0003]     Evaporator devices generally include an array of ice cells arranged in a pattern and a refrigerant tube that is positioned adjacent the pattern to provide cooling during ice making and heating during defrost and harvest. For example, the pattern may be a plurality of parallel rows or a grid of horizontal rows and vertical columns.  
         [0004]     It is known to construct an ice cell array with thermally conductive metal, such as copper or aluminum. An example of a copper evaporator device is shown in U.S. Pat. No. 4,459,824. The evaporator device, when constructed of copper, is plated with a suitable metal, such as tin or nickel. The plating is required by National Sanitation Foundation codes, which prohibit the use of copper parts in contact with food products. The plating process results in waste products that need to be handled with environmentally acceptable procedures. In addition, plating degradation can occur at solder fillets used in the construction of the array of cells or their connection to other parts over which the water used in the ice making process may flow. This can result in a formation of copper oxides that could contaminate the ice.  
         [0005]     Examples of evaporator devices that use aluminum parts to construct the ice cell array are shown in U.S. Pat. Nos. 3,430,452, 5,129,237 and 5,193,357. For instance, U.S. Pat. No. 5,193,357 discloses a plurality of horizontal integral aluminum pieces arranged side by side to form a grid of ice cells. However, the back of each ice cell contains a gap that is filled entirely or partially with brazing material. Brazing material or soldering material can deteriorate over time, thereby resulting in unreliability. Moreover, the evaporator device construction is limited to one-sided ice cell arrays.  
         [0006]     U.S. Pat. No. 6,247,318 discloses an evaporator device comprising a plurality of vertical partitions that are assembled side by side having bore holes through which runs of copper tubing are threaded and then mechanically expanded. External tube bends are then connected as by soldering to the runs to form a contiguous winding. This evaporator device comprises a multiplicity of parts that must be assembled as well as tube bends that are outside the evaporator body formed by the vertical partitions.  
         [0007]     U.S. Pat. No. 5,129,237 discloses an evaporator device constructed of a base plate from which extend row wide fins. The evaporator device is a molded body that includes a plurality of horizontal bores that are interconnected by a plurality of tube bends that are external to the molded body. This arrangement has the disadvantage of requiring assembly of the tube bends to the bores of the body as well as a multiplicity of parts.  
         [0008]     Thus, there is a need for an evaporator device that is not formed with brazing material or soldering material.  
         [0009]     There is also a need for an evaporator device that has a small number of parts.  
       SUMMARY OF THE INVENTION  
       [0010]     An evaporator device of the present invention comprises a metallic body that has a winding pattern of a metallic refrigerant tube embedded therein and that is shaped to have a plurality of parallel fins protruding from a surface thereof. The metallic body is preferably a metal that is selected from the group consisting of: aluminum and aluminum alloy.  
         [0011]     In one embodiment of the evaporator device of the present invention, the winding pattern is entirely embedded in the body. The winding pattern is preferably a serpentine pattern that includes a plurality of runs that are at least partially in registration with spaces between the fins. The refrigerant tube has first and second ends that are located outside the body. The refrigerant tube is preferably a metal that is selected from the group consisting of: copper and stainless steel.  
         [0012]     The fins are preferably inclined downwardly at a slight angle for gravity assistance of ice removal.  
         [0013]     In another embodiment of the evaporator device of the present invention, the metallic body comprises a plurality of vertical partitions protruding from the surface. The vertical partitions, the fins and the surface define an array of ice forming cells. The winding arrangement is at least partially in registration with one or more of the ice forming cells.  
         [0014]     In another embodiment of the evaporator device of the present invention, the metallic body has a first surface with a first plurality of fins protruding therefrom and a second surface with a second plurality of parallel fins protruding therefrom. The winding pattern comprises a plurality of runs that are at least partially in registration with spaces between each of the pluralities of fins.  
         [0015]     In another embodiment of the evaporator device of the present invention, the metallic body further comprises a first plurality of vertical partitions protruding from the first surface and a second plurality of vertical partitions protruding from the second surface. The first vertical partitions, the first fins and the first surface define a first array of ice forming cells. The second partitions, the second fins and the second surface define a second array of ice forming cells.  
         [0016]     A method of the present invention makes an evaporator device for an ice machine by disposing a metallic refrigerant tube having a winding pattern in a casting die and casting molten metal in the die so that the molten metal forms a body that embeds the winding pattern. The die is shaped to form a plurality of fins that protrude from a surface of the body. The metal is preferably selected from the group consisting of: aluminum and aluminum alloy. The refrigerant tube is preferably a metal that is selected from the group consisting of: copper and stainless steel.  
         [0017]     The winding pattern is a preferably a serpentine pattern that includes a plurality of runs that are at least partially in registration with spaces between the fins.  
         [0018]     In another embodiment of the method of the present invention, the refrigerant tube has first and second ends located outside the body.  
         [0019]     In another embodiment of the method of the present invention, the fins are inclined downwardly at a slight angle for gravity assistance of ice removal.  
         [0020]     In another embodiment of the method of the present invention, a plurality of vertical partitions protrude from the surface. The vertical partitions, the fins and the surface define an array of ice forming cells. The winding arrangement is at least partially in registration with one or more of the ice forming cells.  
         [0021]     In another embodiment of the method of the present invention, the metallic body has a first surface having a first plurality of parallel fins protruding therefrom and a second surface with a second plurality of parallel fins protruding therefrom. The winding pattern comprises a plurality of runs that are at least partially in registration with spaces between each of the pluralities of fins.  
         [0022]     In another embodiment of the method of the present invention, a first plurality of vertical partitions protrudes from the first surface and a second plurality of vertical partitions protrudes from the second surface. The first vertical partitions, the first fins and the first surface define a first array of ice forming cells. The second partitions, the second fins and the second surface define a second array of ice forming cells. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0023]     Other and further objects, advantages and features of the present invention will be understood by reference to the following specification in conjunction with the accompanying drawings, in which like reference characters denote like elements of structure and:  
         [0024]      FIG. 1  is a plan view of an evaporator device of the present invention;  
         [0025]      FIG. 2  is a side view of the evaporator device of  FIG. 1 ;  
         [0026]      FIG. 3  is a cross-sectional view of  FIG. 1  taken along line  3 ; and  
         [0027]      FIG. 4  is a view of detail  4  of  FIG. 3 . 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0028]     Referring to  FIGS. 1-4 , an evaporator device of the present invention includes a one-piece or integral body  22  that is a one-piece integral metallic structure in which a refrigerant tube  36  is embedded. Refrigerant tube  36  has tube ends  38  and  40 , which extend outside body  22 .  
         [0029]     Body  22  has a first surface  44  and a second surface  46  that are preferably substantially parallel and opposite one another. Body  22  also includes a plurality of fins  54  that protrude outwardly from first surface  44 . Fins  54  extend horizontally along first surface  44 , are spaced from one another and are substantially parallel. Body  22  further includes a plurality of fins  56  that protrude outwardly from second surface  46 . Fins  56  extend horizontally along first surface  46 , are spaced from one another and are substantially parallel. Fins  54  and  56  are located substantially opposite one another.  
         [0030]     Body  22  further includes a plurality of vertical partitions  28  disposed along first surface  44 . Vertical partitions  28  are spaced apart and parallel to one another. Vertical partitions  28  together with horizontal fins  54  form an array of ice forming cells in rows and columns. Evaporator device  20  further includes a plurality of vertical partitions  32  disposed along second surface  46 . Vertical partitions  32  are spaced apart and parallel to one another. Vertical partitions  32  together with horizontal fins  56  form an array of ice forming cells in rows and columns.  
         [0031]     Body  22  further includes vertical sides  24  and  26  that are substantially parallel to vertical partitions  28  and  32 .  
         [0032]     The ice forming cells on first surface  44  are in substantial registration with the ice forming cells on second surface  46 . Refrigerant tube  36  has a serpentine winding arrangement that has runs  50  along horizontal rows of the ice forming cells. Bends  42  are arranged with runs  50  to form the serpentine pattern.  
         [0033]     Each ice forming cell is substantially identical. By way of example, an ice forming cell  30 , which is depicted in  FIGS. 1, 3  and  4 , will be described in detail. Fins  54 A and  54 B and first surface  44  of body  22  and vertical partitions  28 A and  28 B define ice forming cell  30 . Ice forming cell  30  has a mirror image ice forming cell  34  substantially opposite on second surface  46 . The top most run  50  of refrigerant tube  36  is at least partially in registration with ice forming cells  30  and  34 . Since refrigerant tube  36  is embedded in body  22 , thermal transfer from refrigerant flow in refrigerant tube  36  to ice forming cells  30  and  34  is very efficient.  
         [0034]     Referring to  FIGS. 3 and 4 , the cross-sections of fins  54  and  56  are generally tapered from first and second surfaces to their tips. For example, a surface  60  of fin  54 B has a slight angle of about 30° so as to release an ice cube during a harvest cycle. A surface  62  of fin  54 B has a slight angle of about 15° to assure that water penetrates to rear of ice forming cell  30 .  
         [0035]     In addition, the sides of the cube cells, namely vertical partitions  28  and  32 , are tapered outwardly from first and second surfaces  44  and  46 . Preferably, the angle of taper is about 5°. This is done both to facilitate the casting process and to let air in behind the slab of ice as it begins to slide off body  22 . The angle of taper can be any angle greater than about 1°. As the angle of taper is increased, the material required for the casting increases. The smaller the angle of taper, the less impact it has on harvest because it lets less air in behind the ice.  
         [0036]     Body  22  is made by positioning the serpentine winding arrangement of refrigerant tube  36  in a casting die and then casting molten metal in the die so that the molten metal encases or embeds refrigerant tube  36 . The shape of the die allows refrigerant tube ends  38  and  40  to be located outside the molten metal. The shape of the die also allows vertical partitions  28  and  32  as well as sides  24  and  26  to be formed by the casting process step. Thus, body  22  is formed as a one-piece integral structure in which the winding arrangement of refrigerant tube  36  is embedded or encased.  
         [0037]     The body  22  is preferably aluminum or aluminum alloy and refrigerant tube  36  is preferably copper or stainless steel.  
         [0038]     All surfaces of evaporator device  20  are coated with a coating that prevents corrosion. The coating, for example, may be nickel or tin plating.  
         [0039]     The evaporator device of the present invention has the following advantages:  
         [0040]     1. Enhanced heat transfer. Rather than heat passing through only a part of the surface of the refrigerant tube in contact with the pan holding the ice forming fins, the aluminum encases the refrigerant tube, thereby allowing heat transfer through the full perimeter of the refrigerant tube.  
         [0041]     2. Enhanced heat transfer by virtue of two ice making surfaces using only one copper refrigerant tube.  
         [0042]     3. Reduced part count. There is only a one-piece structure of metallic body  22  with embedded refrigerant tube  36  vis-a-vis a traditional design that has a refrigerant tube, a pan and a plurality of strips.  
         [0043]     4. No reliance on sensitive bonding processes, such as soldering. Thus no chance of the evaporator assembly coming apart.  
         [0044]     5. Lighter weight. (Aluminum vs. copper).  
         [0045]     6. Easier to manufacture.  
         [0046]     Although evaporator device  20  is shown with ice forming cells on both sides of body  22 , it is contemplated that body  22  may have ice forming cells on only one side. In this case, the fins of one side could be omitted or simply not used. Also, the vertical partitions can be omitted for the case that ice cubes are not required. In such case the ice would be formed along the length of the space between adjacent fins.  
         [0047]     The present invention having been thus described with particular reference to the preferred forms thereof, it will be obvious that various changes and modifications may be made therein without departing from the spirit and scope of the present invention as defined in the appended claims.