US3868829A

US3868829A - Insulation divider for refrigerator cabinet

Info

Publication number: US3868829A
Application number: US420528A
Authority: US
Inventors: Leonard J Mann; John A Kemper
Original assignee: Motors Liquidation Co
Current assignee: Motors Liquidation Co
Priority date: 1973-11-30
Filing date: 1973-11-30
Publication date: 1975-03-04
Anticipated expiration: 1992-03-04

Abstract

A refrigerator cabinet having a transverse partition for dividing the cabinet into an upper freezer compartment and a lower food storage compartment. The partition includes a composite insulation separator and drain trough structure in the form of a molded moisture impervious sealed plastic separator shell completely filled with unfused pre-expanded polystyrene contacting beads, each of the beads being substantially spherical in shape and having a diameter of the order of 0.060 to 0.100 inches whereby convection heat transfer between the upper and lower shell walls is obviated.

Description

imited States Patent [1 1 [11] 3,868,829 Mann et al. Mar. 4, 1975 1 INSULATION DIVIDER FOR 3.766.749 /1973 Linesay 62/289 REFRIGERATOR CABINET 3.774.408 ll/l973 Pruehs 62/285 [75] Inventors: Leonard J. Mann, Kettering; John v Primary E.\ammer-Wlllram J. Wye Kemper Beubrook both of Ohio Attorney, Agent, or Firm-Edward P. Barthel [73] Assignee: General Motors Corporation,

Detroit, Mich. [57] ABSTRACT [22] Flled: 1973 A refrigerator cabinet having a transverse partition for [21] Appl. No.: 420,528 dividing the cabinet into an upper freezer compartment and a lower food storage compartment. The partition includes a composite insulation separator and 2% 62/285 i i drain trough structure in the form of a molded moisi 288 789 ture impervious sealed plastic separator shell com- 1 0 can pletely filled with unfused pre-expanded polystyrene contacting beads, each of the beads being substantially [56] References Cited spherical in shape and having a diameter of the order UNITED STATES PATENTS of 0.060 to 0.100 inches whereby convection heat 3.280.583 10/1966 Jones 62/285 transfer between the upper and lower shell walls is ob 3.320.764 5/1967 Saunders... viated. 3.599.442 8/l97l Hanson..... 3.724.233 4/1973 Pugh 62/288 3 Claims, 6 Drawing Figures l l I l l t I 60 a) e r. l V 1 76 [Li]: 7% l I .66 t

If s

5% a? if a; a

PATENTEDMAR 4W5 3,868,829 sum 2 95 3 INSULATION DIVIDER FOR REFRIGERATOR CABINET This invention relates to refrigerator cabinet construction and more particularly to a moisture barrier composite plastic insulation and drain trough separator located between the freezer and food storage compartments of the refrigerator.

The prevention of water vapor migrating into rigid plastic foam cellular insulation dividers for refrigerator cabinets has long been a problem. The fact that moisture adversely affects the performance of insulation is generally known wherein moisture pick-up in the divider insulation causes resultant frost forming thermo conductive bridges from the warm to the cold side of the insulation. The problem manifests itself as drops of water or frost on the top wall of the food compartment liner of the refrigerator.

It is an object of this invention to provide an insulation divider or separator between the freezer and fresh food compartments ofa domestic refrigerator compartment wherein a composite plastic divider includes a molded polyethylene sealed outer shell which is completely filled with unfused pre-expanded polystyrene beads, each of the beads being substantially spherical in shape and having a diameter of the order of 0.060 to 0.100 inches whereby the plastic outer shell serves as the vapor barrier such that the expanded polystyrene beads and entrapped air providing the required insulating medium with the preexpanded unfused beaded core serving to obviate the development of air circulation currents within the shell which, if permitted, would produce unwanted convection heat transfer between the upper and lower walls of the separator.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings wherein a preferred embodiment of the present invention is clearly shown.

In the Drawings:

FIG. 1 is a perspective view of a refrigerator cabinet showing the location of the insulation divider of the present invention;

FIG. 2 is a top elevational view of the insulation divider;

FIG. 3 is a back elevational view taken along the lines 3-3 of FIG. 2;

FIG. 4 is a side elevational view taken along the line 4-4 of FIG. 2;

FIG. 5 is a fragmentary side elevational view along line 55 of FIG. l; and

FIG. 6 is an enlarged vertical sectional view taken along the line 6-6 of FIG. 2.

Referring now to the drawings and more particularly to FIG. 1, there is shown an insulated household refrigerator cabinet IO'having an outer metal shell 11 with the visible portions including right hand side wall 12, top wall 13, bottom wall 14 including an upper offset portion 16 which forms the ceiling of the machinery compartment therebelow.

The cabinet is provided with an upper below-freezing compartment 22, and a lower above-freezing or cooling compartment 24, both being enclosed within an inner liner preferably formed out of suitable sheet plastic such as acrylic butadienc styrene copolymer with the liner side wall 26 and rear wall 27 being visible in FIG. I. The space between the inner walls, formed by the inner liner and the other metal shell 11, is filled with expanded polyurethane foam which is conventional practree.

The sidewalls 12 and the top Wall 13 are reinforced at the front with an inwardly turned flange 28 extending inwardly substantially at right angles to the side and top walls around the access opening of the cabinet. Suitable brackets (not shown) extend through openings in flange 28 and support a front metal cross member (FIG. 5) extending between them. The details of one such refrigerator cabinet construction are shown, for example, in US. Pat. No. 3,633,374 issued to James A. Canter and assigned to the same assignee as the present application.

As best seen in FIG. 5, the compartments are separated by an insulated horizontal partition assembly 30 which includes a lower sheet metal wall 32 having a high front portion 34 and a low rear portion 36 with an inclined portion 38 in between. The top member 40 of the partition assembly is provided with a series of air entrances 42 which connects with the air passages 44 in the front insulation piece 46 and with the evaporator chamber 48. The evaporator chamber 48 is also surrounded by an insulation piece SU having a passage 52 providing communication with the air entrance 54 from the above freezing compartment 26 to the evaporator chamber 48.

The evaporator chamber 48 includes an evaporator 56 which is supported on the drain pan 57. The evaporator is supplied with liquid refrigerant in a manner shown and described in the above-mentioned Canter patent. A fan motor 58 is provided with a front inlet centrifugal fan 60 at the rear which draws air through the air inlets 42 and 54 into the evaporator chamber 48 and through the evaporator 56 discharging the air upwardly through the duct 62 into below freezing compartment 22 while a reduced amount of air is discharged downwardly through the duct 64 into the above freezing compartment 26. A light socket 66, provided with a light bulb 68, is controlled by a door switch and plunger 72 to extinguish the bulb 68 when the lower door partially shown at 74, is closed. A metal trim strip 76 is supported on a front metal cross member 29 extending between suitable side wall brackets (not shown).

Defrost heaters 80 melt the frost from the evaporator 56 and the frost water resulting therefrom flows into the drain pan 57 and its integral drainage funnel portion 82 formed therein including tubular end orifice 83.

Located in the partition space between the upper drain pan 57 and the lower wall 32 is a thermal insulation divider or separator generally indicated at 84 in the form of a composite plastic panel or article including a molded outer plastic shell or envelope having an upper wall 86 and a bottom or lower wall 88, a front outwardly sloping wall 90, a rear wall 92, and

sidewalls

93 and 94. It will be noted in FIG. 6 that the shell bottom wall 88 terminates in an L-shaped flange portion having upwardly directed flange leg 96 and an outwardly extending flange leg 97 which form a flush seal juncture with the peripheral rear edge portion 98 of drain base wall 100. The outer shell is preferably formed by blow molding from suitable plastic material which in the preferred form is polyethylene plastic having a material thickness of about 0.06 inches.

As best seen in FIG. 2, the shell [upper wall 86 has integrally formed therein a depressed longitudinally extending rearwardly sloped drain trough defined by the drain trough base 100 and

side slopes

102 and 104 forwardly converging in a semicircular or arcuate portion 106 having its center vertically aligned and concentric with the exit orifice 83 of drainage pan funnel 82. Thus, as seen in FIGS. 5 and 6, the melted frost water collected by the drain pan 57 flows from the funnel 82 to exit via orifice 83 into the separator drain trough for flow on the base 100 to the lower rear wall 27 to a drain 110 (FIG. 1) in the bottom wall 14 of the cabinet.

As seen in FIGS. 3 and 4, entrance means for the divider shell or envelope may be provided in the form of an upwardly extending integral tube 112 formed in top wall. By means of the tube 112 the divider shell is completely filled with unfused pre-expanded polystyrene beads, indicated at 114 in FIG. 6, each bead being generally spherical in shape and having a diameter within the range of about 0.060 to 0.100 inches. The beads 114, which preferably have a density of the order of about 2 pounds per cubic foot, after filling the space enclosed by the panel shell are sealed therein and the tubular portion 112 removed from the upper wall 86.

The beads 114 are originally formed from polystyrene spheres which have been treated with Freon solvent, either gas or liquid, or alternatively with a low boiling solvent such as pentane. The spheres, which are originally about 0.030 inches in diameter, absorb about 6-8 percent of the solvent after which they are expanded unconfined by either dry heat or steam injection with the result that the absorbed solvent expands the spheres to their pre-expandecl beaded state.

As seen in FIG. 5, the pre-expanded beads 114 completely fill the sealed air space of the divider shell to provide a plurality of voids occupied by the entrapped air, which beads and air thus form the core material for the insulation divider 84. A function of the contacting beads is to prevent the formation of circulating convection air currents within the moisture impervious sealed plastic divider shell which would result from the temperature differential between the shell top wall 86, exposed to freezer compartment temperature ranging from about 2 to +15F. and the shell bottom wall 88 exposed to the above freezing food storage compartment temperatures ranging from about 34 to 40F.

It will be noted in FIGS. 5 and 6 that the arcuate sloped portion 106 of the divider top wall is molded to conform with the funnel portion 82 of the drain pan while inner inclined arcuate notch 120 encloses about l80 of the downwardly extending circular lip portion of the funnel 82. In this way only the drain base 100 and the adjacent drain side

steep slopes

122 and 124 extending between the base 100 and the reduced

slopes

102 and 104 are open to allow defrost water to drain to the refrigerator rear wall.

As the defrost heaters 80 are of the infra-red emitting type, certain portions of the drain base 100 and

steep slopes

122 and 124 are exposed to the infra-red rays which rays would melt and destroy the portions of the plastic shell exposed to the rays. To obviate this from occurring an aluminum foil strip or tape 126 is affixed to the upper surface of the drain base 100 and the

steep side slopes

122 and 124 to reflect the infrared rays and protect the underlying plastic material therefrom.

It will thus be seen that applicants have invented an improved insulation separator panel for refrigerators whereby the panel upper and lower walls are molded to conform to and contiguous with the overlying drain pan and the underlying supporting wall, respectively to form a moisture impervious airtight insulator for a refrigerator cabinet with the sealed cavity being filled with the beads 114 whereby static air therein is confined in the air spaces between the beads to minimize convection heat transfer between the upper and lower walls of the separator shell.

While the embodiment of the present invention as herein disclosed constitutes a preferred form, it is to be understood that other forms might be adopted.

We claim:

1. A refrigerator including a cabinet having insulated walls enclosing a compartment, a laterally extending dividing means within said compartment dividing said compartment into an upper freezer compartment and a lower fresh food compartment, door means for closing said compartments, said dividing means including a bottom supporting wall, a drain pan spaced above said supporting wall for supporting an evaporator thereon, wherein the improvement comprises an insulation separator on said supporting wall, said separator comprising an outer molded moisture impervious plastic shell having upper, bottom, front, rear and side walls forming an air-tight sealed chamber, said shell upper and bottom walls substantially conforming to and contiguous with said drain pan and said supporting wall, respectively; said sealed chamber completely filled with unfused, pre-expanded polystyrene contacting beads; each of said beads being substantially spherical in shape and having a diameter of about 0.060 to 0.100 inches, said beads forming a plurality of air spaces therebetween so that static air is confined in the air spaces whereby convection heat transfer between the upper and lower walls of said separator shell is obviated.

2. A refrigerator including a cabinet having insulated walls enclosing a compartment, a laterally extending dividing means within said compartment dividing said compartment into an upper freezer compartment and a lower fresh food compartment, door means for closing said compartments, said dividing means including a bottom supporting wall, a drain pan spaced above said supporting wall for supporting an evaporator thereon, said drain pan including an integral frustoconical drainage funnel formed therein having an exit orifice, wherein the improvement comprises; a composite insulation separator and drain trough supported on said bottom supporting wall, said separator comprising an outer molded plastic shell having upper, bottom, front, rear and side walls forming a sealed chamber, recess means molded in said upper wall surface for conducting drainage water from said funnel to a wall of said cabinet, said chamber being completely filled with unfused, pre-expanded polystyrene contacting beads, said beads being substantially spherical in shape and having a diameter within the range of about 0.060 to 0.100 inches, and a density of the order of two pounds per cubic foot; said beads forming a plurality of air spaces therebetween so that static air is confined in the spaces whereby convection heat transfer between said upper and lower walls of said separator shell is obviated.

3. A refrigerator including a cabinet having insulated top, bottom, rear and side walls enclosing a compartment; a laterally extending dividing means within said compartment dividing said compartment into an upper freezer compartment and a lower fresh food compartment, door means for closing said compartments, said dividing means including a bottom sheet metal wall having a high front portion and a low rear portion with an inclined connecting portion in between, a drain pan spaced above said sheet metal wall low rear portion for supporting an evaporator thereon, said drain pan including an integral frusto-conical drainage funnel formed therein having an exit orifice, wherein the improvement comprises; a composite insulation separator and drain trough supported on said sheet metal wall low rear portion, said separator comprising an outer molded shell of polyethylene plastic material having upper, bottom, front, rear and side walls forming a sealed chamber; said sealed chamber completely filled with unfused, pre-expanded polystyrene contacting beads having a substantially spherical shape and having a diameter within the range of about 0.060 to 0.100 inches, said beads forming a plurality of air spaces therebetween so that static air in said chamber is confined in the spaces whereby convection heat transfer between the upper and lower walls of said separator shell is obviated, and said separator upper wall surface having a plurality of inwardly sloping walls defining a recess extending longitudinally from the rear wall of said separator and terminating adjacent the center of said upper surface in an arcuate portion conforming with said frusto-conical drainage funnel, the base of said recess being sloped toward said separator rear wall for directing the flow of drainage water from said drainage funnel to said refrigerator cabinet rear wall.

Claims

2. A refrigerator including a cabinet having insulated walls enclosing a compartment, a laterally extending dividing means within said compartment dividing said compartment into an upper freezer compartment and a lower fresh food compartment, door means for closing said compartments, said dividing means including a bottom supporting wall, a drain pan spaced above said supporting wall for supporting an evaporator thereon, said drain pan including an integral frusto-conical drainage funnel formed therein having an exit orifice, wherein the improvement comprises; a composite insulation separator and drain trough supported on said bottom supporting wall, said separator comprising an outer molded plastic shell having upper, bottom, front, rear and side walls forming a sealed chamber, recess means molded in said upper wall surface for conducting drainage water from said funnel to a wall of said cabinet, said chamber being completely filled with unfused, pre-expanded polystyrene contacting beads, said beads being substantially spherical in shape and having a diameter within the range of about 0.060 to 0.100 inches, and a density of the order of two pounds per cubic foot; said beads forming a plurality of air spaces therebetween so that static air is confined in the spaces whereby convection heat transfer between said upper and lower walls of said separator shell is obviated.