US3835660A

US3835660A - Refrigerator cabinet construction

Info

Publication number: US3835660A
Application number: US00322976A
Authority: US
Inventors: H Franck
Original assignee: Philco Ford Corp
Current assignee: Space Systems Loral LLC
Priority date: 1973-01-12
Filing date: 1973-01-12
Publication date: 1974-09-17
Anticipated expiration: 1991-09-17
Also published as: CA1002574A

Abstract

Refrigerator cabinet construction including an outer shell and a double compartment inner liner formed from a single sheet of thermoplastic material and having, in the general plane of the doors, a mullion provided between the two compartments and against which adjacent edges of the doors are adapted to seal. A portion of the hot gas line from the refrigerator condenser system extends along the rear surface of the mullion, between the adjacent side walls of the two compartments, to prevent condensation upon the exterior surface of said mullion by insuring that it is maintained at a temperature above the dew point of the ambient air. A strip of semi-flexible material of high magnetic permeability extends along the length of the mullion and has said dew point compensator tubing secured in high heat exchange relation with its rearwardly presented surface. During manufacture of the refrigerator the forwardly presented surface of said strip is maintained in intimate contact with the interior surface of the mullion through the agency of elongated magnetic means which is disposed adjacent the outer surface of the mullion during assembly of the cabinet, and particularly during foaming of insulation in the space between the inner liner and outer shell. The foamed-in-place insulation presses against the resilient strip and maintains it in good thermal relation with the interior surface of the mullion, after the magnetic means has been removed. In the resultant cabinet construction the intimate contact between the strip of material of high permeability and the interior surface of the mullion insures high heat exhange relation between the dew point compensator tube and the mullion, the strip at the same time being available as an armature, permitting use of door sealing gaskets of the magnetic type.

Description

United States Patent [191 Franck [111 3,835,660 [451 Sept. 17, 1974 Howard S. Franck, Oxford, Ohio [73] Assignee: Philco-Ford Corporation, Blue Bell,

[22] Filed: Jan. 12, 1973 [21] App]. No.: 322,976

[75] Inventor:

Primary Examiner-James C. Mitchell Attorney, Agent, or FirmHarry W. Hargis, III; Carl H. Synnestvedt; Robert D. Sanborn 7 1 ABSTRACT Refrigerator cabinet construction including an outer shell and a double compartment inner liner formed from a single sheet of thermoplastic material and having, in the general plane of the doors, a mullion provided between the two compartments and against which adjacent edges of the doors are adapted to seal.

A portion of the hot gas line from the refrigerator condenser system extends along the rear surface of the mullion, between the adjacent side walls of the two compartments, to prevent condensation upon the exterior surface of said mullion by insuring that it is maintained at a temperature above the dew point of the ambient air. A strip of semi-flexible material of high magnetic permeability extends along the length of the mullion and has said dew point compensator tubing secured in high heat exchange relation with its rearwardly'presented surface. During manufacture of the refrigerator the forwardly presented surface of said strip is maintained in intimate contact with the interior surface of the mullion through the agency of elongated magnetic means which is disposed adjacent the outer surface of the mullion during assembly of the cabinet, and particularly during foaming of insulation in the space between the inner liner and outer shell. The foamed-in-place insulation presses against the resilient strip and maintains it in good thermal relation with the interior surface of the mullion, after the magnetic means has been removed.

In the resultant cabinet construction the intimate contact between the strip of material of high permeability and the interior surface of the mullion insures high heat exhange relation between the dew point compensator tube and the mullion, the strip at the same time being available as an armature, permitting use of door sealing gaskets of the magnetic type.

3 Claims, 11 Drawing Figures REFRIGERATOR CABINET CONSTRUCTION BACKGROUND A refrigerator cabinet in common use is provided with a pair of adjacent compartments, frequently arranged in side-by-side relation, each having its own door. The inner adjacent edges of the two doors seal against a mullion which extends throughout a major dimension of the two compartments and in the plane of the openings thereto. These and certain other cabinets present problems arising from the fact that portions of their outside surface may be cooled below the dew point temperature of surrounding air, with resultant condensation of moisture. Frequently the mullion provided between the doors tends to collect condensation and various means have been utilized to raise the temperature of the mullion.

In certain particularly advanced refrigerators of the foregoing kind the cabinets include dual compartment inner liners fabricated from a single sheet of thermoplastic material. In such a construction the mullion is formed integrally with the two adjacent compartments and difficulties have arisen in effecting proper association of the dew point compensator with the interior surface of the mullion. An additional problem in such a refrigerator is that the plastic mullion does not provide an armature to which magnetic door gaskets are attracted for sealing purposes.

It is the general objective of my invention to provide an improved method of cabinet fabrication which makes it possible to insure securement of the dew point compensator against the mullion as a result of forces generated during the foaming of insulation in the space between the plastic outer shell and inner liner, whereby to provide a cabinet which is not only free from objectionable condensation upon the mullion, but also enables use of magnetic sealing gaskets in conjunction with a mullion of plastic material. The invention also has as an object the provision of novel apparatus which results from practice of the method.

SUMMARY OF THE INVENTION In achievement of the foregoing general objectives, the invention contemplates a novel method of fabricating a refrigerator cabinet having an integral dual compartment plastic liner. This method makes it possible to use a hot gas bypass line from the condenser to raise the temperature of the mullion, rather than the more expensive and less desirable electric heaters. I provide an armature of magnetically permeable material, for example, vinyl impregnated with barium ferrite, which takes the form of an extruded semi-flexible strip having a flat surface which is disposed in contact with the interior surface of the mullion and is maintained in that position throughout the foaming operation by the use of a magnet disposed exteriorly f the mullion. If the external magnet is of the electro-magnetic type it may be energized after the inner liner has been disposed within the outer shell and just prior to the foaming operation. The external magnet then attracts the magnetic strip, and the tube carried on the back surface thereof, and holds said strip in intimate contact with the rear side of the mullion. After the foaming is complete the external magnet is removed and the cured foam retains the dew point compensator tube, and the strip which carries the same, in proper position. It is a particular advantage of the resultant construction that the strip of magnetic material which extends throughout the length of the inside surface of the mullion is then available as an armature, cooperable with magnetic door gaskets in sealing of the latter against the mullion.

Certain preferred embodiments of the invention have the additional advantage that the armature includes a tube-carrying recess having opposed surfaces which are maintained in doubleline contact with opposite sides of the tube, thereby increasing the transmission of heat from the tube to the armature and thence to the mullion.

BRIEF DESCRIPTION OF THE DRAWINGS In the accompanying drawings:

FIG. 1 is a small scale perspective view of a refrigerator cabinet embodying a liner having two integrally formed compartments and an interposed mullion of the kind with which use of the invention is particularly advantageous;

FIG. 2 is a perspective view of apparatus shown in FIG. 1, but with the major portion of the outer shell and insulation broken away to show the compartment liner;

FIG. 3 is a sectional view, on a larger scale, taken through the forward portion of the mullion of the cabinet shown in FIG. 1, and illustrating the external magnetic means used during the fabrication process;

FIG. 4 is a somewhat diagrammatic, perspective illustration of the outer shell, showing dew point compensator tubing associated therewith prior to mounting of the inner liner within said shell;

FIG. 5 is a sectional view through the outer shell and inner liner, illustrative of the way in which the shell and liner interfit, and showing the cabinet after foaming of the insulation in the space between said shell and liner;

FIG. 6 is a detail view showing a clip of a type which may be used to support a portion of the dew point compensator tube in association with the intumed side flanging of the outer shell; and

FIGS. 7A through 7E are detailed sectional showings of a variety of ways in which compensator tubing may be associated with the semi-flexible magnetic strip which comprises the armature.

DESCRIPTION OF THE ILLUSTRATED EMBODIMENT In the accompanying drawings there is illustrated at 10 a double compartment refrigerator with which the apparatus of the invention is particularly, although not solely, usable. This refrigerator is provided with a pair of adjacent compartments 11 and 12 disposed in sideby-side relation and each having its own door, shown at 13 and 14 respectively. As is common in such refrigerators, one of the compartments, in this case compartment 11, comprises a freezing compartment, while compartment 12 is maintained at above freezing food storage temperatures. Any suitable refrigerating system, of known type, may be used to maintain the desired temperatures. The compartments are defined by an inner liner L, which appears to good advantage in FIGS. 2 and 5, said liner being of thermoplastic material and being nested within an outer shell 15 which may be of metal. In a refrigerator of the kind with which the invention is especially concerned, the liner compartments 11 and 12 are vacuum-formed from a single sheet of thermoplastic material, by the use of suitable adjacent molds and mold assist-plugs. As disclosed and claimed in US. Pat. No. 3,709,968, issued Jan. 9, 1973, and assigned to the assignee of the present invention, the molds are moved during the vacuumforming operation to permit close spacing of the deep drawn

adjacent walls

16 and 17 of the two compartments (FIG. 2). As is now known in this art thermoplastic inner liners may be disposed within outer shells, for example the outer shell shown in the drawings at 15, and insulation 18 is foamed in place between the shell and liner. As will become clear as this description proceeds the cured foam 18 bears against the combined armature and dew point compensator structure characteristic of this invention, to hold the latter structure in high heat exchange relation with the interior surface of a mullion 19 which bridges the gap between said

adjacent liner walls

16 and 17, and against which mullion the doors of the refrigerator are adapted to seal, as appears to best advantage in FIG. 5.

As known to those skilled in this art, refrigerator cabinets, particularly cabinets provided with a plurality of doors, frequently present exterior surface portions which may be cooled to temperatures below the dew point temperature of the surrounding air. Objectionable condensation results. The region of the mullion 19 is a surface particularly prone to the condensation problem.

In accordance with the present invention I have provided a unique dew point compensator assembly of strip-like form which can readily be inserted in the narrow space between the

liner walls

16 and 17, and be maintained in close adjacency with the interior surface of the mullion 19, through the agency of forces generated during the foaming of insulation 18. Strip-like dew point compensator support structure is shown at 20 (see particularly FIG. 3) and extends along a substantial portion of the length of the cabinet (FIG. 4). It is a feature of my invention that this compensator structure also serves as an armature against which magnetic door gaskets are attracted for sealing purposes. The

doors

13 and 14 are shown in FIG. as including interior edges, disposed in adjacency when the doors are closed, which edges carry magnetic type sealing gaskets as shown at 21.

Preferably the combined armature and compensator support structure is of semi-flexible material and may, for example, comprise vinyl impregnated with barium ferrite. The side of this strip 20, which is adapted to be disposed away from the inside surface of the mullion 19, is provided with elongated clamping means 20a which extends along the length of the strip 20 and serves to clamp a portion of tubing 22 in high heat exchange relation with strip 20. Although, in one aspect of the invention, electrical dew point compensator means may be associated with the strip 20, it is desirable that the compensator take the form of a pass of tubing which is connected in the refrigerating system (not shown) as a part of the condenser circuit. Such tubing, when maintained in high heat exchange relation with the thermoplastic mullion, will raise the temperature of the latter sufficiently to prevent condensation of moisture on the mullion.

In accordance with the method of this invention, the outer shell 15, shown somewhat diagrammatically in FIG. 4, is provided, prior to mounting of the inner liner L, with a U-shaped loop of tubing, one leg of which extends along the under surface of the left hand flange structure 23 of the shell and the other leg of which comprises the mullion compensator 22. As mentioned, the ends of this loop of tubing are coupled in the condensing side of the system.

During fabrication of the refrigerator the tubing is maintained in its proper position with respect to the outer shell 15, through the agency of clips shown at 24 in FIG. 6 which cooperate with the side flanging of the shell, and by virtue of the fact that the central unsupported pass 22 thereof has clampingly associated therewith the armature strip 20, in the manner shown in FIGS. 3 and 4. The plastic inner liner L is inserted into the outer shell with mullion 19 overlying the associated tube and armature and with

adjacent liner walls

16 and 17 straddling the armature structure (FIG. 5).

The liner and shell assembly is then loaded into a suitable foaming fixture, for example a fixture similar to that illustrated and described in the above referenced patent and magnetic means, preferably an elongated electromagnet M (FIG. 3), is moved into position to confront and contact the exterior surface of the mullion 19. The magnet means is shown in such contact in FIG. 3, and it should be understood that, while it may conveniently comprise an electromagnet, a strong permanent magnet may be utilized. Regardless of the type of magnetic means, it should be understood that the magnet would extend along the mullion, or at least be effective at several spaced points therealong, and that it would be moved translationally into contact with the mullion, as suggested by the dotted lines in FIG. 3. When this magnet is energized, it attracts the armature strip 20 and the tubing 22 carried thereby, causing the forward surface of strip 20 to be held in close contact with the rear side of the mullion l9. Insulation is then foamed in place, in known manner, between the shell and liner, filling the space therebetween as is clearly illustrated in FIG. 5. The foamed insulation bears against the rear surface of the strip 20 and the foam, after curing, retains the dew point compensator tube and the strip 20 in position closely contacting the mullion. In this position, and as now will be understood, the strip 20, which is of material of high magnetic permeability, is available to cooperate with the door gaskets in sealing of the latter against the thermoplastic mullion.

It is another feature of the apparatus that particularly good thermal contact between the tubing and the armature strip is insured, since the tubing is carried within a recess which has opposed surfaces maintaining double line contact with the tubing, as illustrated at 25 and 26 in FIG. 3. As shown in FIGS. 7A to 7B, the clamping channel shown in FIG. 3 may take other forms. For example, in FIG. 7A, there is shown an armature strip 20a having a pair of opposed U-shaped tube-carrying recesses 27. This arrangement, as well as the arrangement shown in FIG. 7D, may be utilized where it is desired to have more than a single pass of tubing disposed behind the mullion. In the apparatus of FIG. 7D tube clamping structure 28 is generally T-shaped. FIGS. 78 and 7E show variations in which, respectively, double and single tube arrangements are supported by recessing the material of the armature strip along lines extending throughout the length of the strip. Two such recesses appear at 29 in FIG. 7B, while a single recess is shown at 30 in FIG. 7E. These arrangements have the advantage of particularly good thermal contact between the tube and the armature structure. An additional arrangement appears in FIG. 7C, in which a double-wall curved clamp 31 substantially surrounds and engages the tubing.

I claim:

1. A refrigerator cabinet, comprising: an outer shell; an inner liner of thermoplastic material nested within said outer shell, said liner presenting a first strip of thermoplastic material having an interior surface facing the insulation space and an exterior surface against which the refrigerator door structure is adapted to seal; a second strip of material having one surface adjacent said interior surface of said first strip and another surface opposite the one surface and facing the insulation space, said second strip being a material of high magnetic permeability; dew point compensator means extending along the recited other surface of said second strip and secured in high heat exchange relation therewith; and insulation foamed in place within the space between the shell and liner, and bearing against said second strip to mount the same in close contact with the interior surface of said first strip.

2. A refrigerator cabinet in accordance with claim 1, in which said dew point compensator means comprises refrigerant tubing, and said second strip includes structure defining a recess having opposed surfaces which are clamped in double-line contact with opposite sides of said tubing.

3. A refrigerator cabinet, comprising: an outer shell; a double compartment liner formed from a single sheet of thermoplastic material nested within said outer shell, said liner having, in the general plane of the compartment openings, a mullion extending between the two compartments against which edges of compartment doors are adapted to seal; a strip-like armature of high magnetic permeability extending along the interior surface of said mullion and with one surface of said armature in close contact with the interior surface of said mullion; dew point compensator means secured in high heat exchange relation with the opposite surface of said strip-like armature; thermal insulation foamed in place between said shell and liner and bearing against said armature to maintain the same in intimate contact with said mullion of said thermoplastic inner liner in provision of high heat exchange relation between said dew point compensator means and said mullion through the intermediacy of said armature; and door structure carrying gasket means of the magnetic type, the magnetic gasket means of said door structure, when the latter is in closed position, being attracted to said armature whereby to seal the door structure against the thermoplastic mullion.