Evaporator device with improved heat transfer and method

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

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

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

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.

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.

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.

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.

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.

Thus, there is a need for an evaporator device that is not formed with brazing material or soldering material.

There is also a need for an evaporator device that has a small number of parts.

SUMMARY OF THE INVENTION

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.

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.

The fins are preferably inclined downwardly at a slight angle for gravity assistance of ice removal.

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.

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.

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.

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.

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.

In another embodiment of the method of the present invention, the refrigerant tube has first and second ends located outside the body.

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.

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.

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.

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

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:

FIG. 1 is a plan view of an evaporator device of the present invention;

FIG. 2 is a side view of the evaporator device of FIG. 1;

FIG. 3 is a cross-sectional view of FIG. 1 taken along line 3; and

FIG. 4 is a view of detail 4 of FIG. 3.

DESCRIPTION OF THE PREFERRED EMBODIMENT

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.

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.

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.

Body 22 further includes vertical sides 24 and 26 that are substantially parallel to vertical partitions 28 and 32.

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.

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 54A and 54B and first surface 44 of body 22 and vertical partitions 28A and 28B 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.

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 54B has a slight angle of about 30° so as to release an ice cube during a harvest cycle. A surface 62 of fin 54B has a slight angle of about 15° to assure that water penetrates to rear of ice forming cell 30.

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.

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.

The body 22 is preferably aluminum or aluminum alloy and refrigerant tube 36 is preferably copper or stainless steel.

All surfaces of evaporator device 20 are coated with a coating that prevents corrosion. The coating, for example, may be nickel or tin plating.

The evaporator device of the present invention has the following advantages:

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.

2. Enhanced heat transfer by virtue of two ice making surfaces using only one copper refrigerant tube.

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.

4. No reliance on sensitive bonding processes, such as soldering. Thus no chance of the evaporator assembly coming apart.

5. Lighter weight. (Aluminum vs. copper).

6. Easier to manufacture.

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.

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.

Claims

1. An evaporator device for an ice machine comprising 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.

2. The evaporator device of claim 1, wherein said body is a metal that is selected from the group consisting of: aluminum and aluminum alloy.

3. The evaporator device of claim 1, wherein said winding pattern is entirely embedded in said body, and wherein said winding pattern is a serpentine pattern that includes a plurality of runs that are at least partially in registration with spaces between said fins.

4. The evaporator device of claim 1, wherein said refrigerant tube has first and second ends located outside said body.

5. The evaporator device of claim 1, wherein said fins are inclined downwardly at a slight angle for gravity assistance of ice removal.

6. The evaporator device of claim 1, wherein said refrigerant tube is a metal that is selected from the group consisting of: copper, and stainless steel.

7. The evaporator device of claim 1, wherein said metallic body comprises a plurality of vertical partitions protruding from said surface, wherein said vertical partitions, said fins and said surface define an array of ice forming cells.

8. The evaporator device of claim 7, wherein said winding arrangement is at least partially in registration with one or more of said ice forming cells.

9. The evaporator device of claim 1, wherein said surface is a first surface, wherein said plurality of fins is a first plurality of fins, and wherein said body is shaped to have a second surface with a second plurality of parallel fins protruding therefrom.

10. The evaporator device of claim 9, wherein said winding pattern comprises a plurality of runs that are at least partially in registration with spaces between each of said pluralities of fins.

11. The evaporator device of claim 9, wherein said metallic body further comprises a first plurality of vertical partitions protruding from said first surface and a second plurality of vertical partitions protruding from said second surface, wherein said first vertical partitions, said first fins and said first surface define a first array of ice forming cells, and wherein said second partitions, said second fins and said second surface define a second array of ice forming cells.

12. A method of making an evaporator device for an ice machine comprising:

disposing a metallic refrigerant tube having a winding pattern in a casting die; and

casting molten metal in said die so that said molten metal forms a body that embeds said winding pattern, wherein said die is shaped to form a plurality of fins that protrude from a surface of said body.

13. The method of claim 12, wherein said metal is selected from the group consisting of: aluminum and aluminum alloy.

14. The method of claim 12, wherein said winding pattern is a serpentine pattern that includes a plurality of runs that are at least partially in registration with spaces between said fins.

15. The method of claim 12, wherein said refrigerant tube has first and second ends located outside said body.

16. The method of claim 12, wherein said fins are inclined downwardly at a slight angle for gravity assistance of ice removal.

17. The method of claim 12, wherein said refrigerant tube is a metal that is selected from the group consisting of: copper and stainless steel.

18. The method of claim 12, further comprising a plurality of vertical partitions protruding from said surface, wherein said vertical partitions, said fins and said surface define an array of ice forming cells.

19. The method of claim 18, wherein said winding arrangement is at least partially in registration with one or more of said ice forming cells.

20. The method of claim 12, wherein said surface is a first surface, wherein said plurality of fins is a first plurality of fins, and wherein said body is shaped to have a second surface with a second plurality of parallel fins protruding therefrom.

21. The method of claim 20, wherein said winding pattern comprises a plurality of runs that are at least partially in registration with spaces between each of said pluralities of fins.

22. The method of claim 20, further comprising a first plurality of vertical partitions protruding from said first surface and a second plurality of vertical partitions protruding from said second surface, wherein said first vertical partitions, said first fins and said first surface define a first array of ice forming cells, and wherein said second partitions, said second fins and said second surface define a second array of ice forming cells.