Insulated wall and method of manufacture

June 23, 1964

R. J. CARBARY 3,137,900

INSULATED WALL AND METHOD OF MANUFACTURE

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ATTORNEY

3,137,900

Patented June 23, 1964

United States Patent Office to the construction of refrigerator doors using foamed insulation generated within the door after the inner and outer panels have been assembled, and provides means whereby the respective door panels are securely keyed 5 to the solidified body of insulation.

In practicing the invention as applied to a construction in which foam insulation is used, I provide a conventional metal outer door panel having upstanding side walls which terminate in inwardly directed flange portions oc10 cupying a common horizontal plane. These flange portions are relatively narrow and define an opening whereby the door, when resting on its outer panel, resembles a basin-like structure. I provide also a conventional inner panel which may be a sheet of plastic shaped by well 15 known vacuum forming technique, by injection molding, or other conventional means. This inner panel has a flat outermost wall portion extending about its periphery, and its longitudinal and transverse dimensions are respectively less than the longitudinal and transverse dimen20 sions of the opening defined by the outer panel flanges.

To bridge the gap between the inner panel and outer panel flanges and also to provide for the securement of the panels one to the other, I utilize an extruded, plastic channel having sidewardly extending flanges which are 25 arranged to grip either or both of the adjacent panel elements. Its exterior and interior walls may advantageously be provided with ribs or other frictional or keying elements.

In the manufacture of the door, the outer panel is ³⁰ placed on a table, and to the flanges of said panel or to the side wall portions of the inner panel, according to the type of structure used, I apply the extruded channel member with the channel opening facing outwardly. In this arrangement the body portion of the channel will extend ³⁵ below the surface of the element to which it is applied.

I then introduce into the outer panel a mixture of materials which will produce a foam and will harden into a porous rigid mass. For example, the foam may comprise polyurethane resin employing a low boiling vaporizable ⁴⁰ liquid such as trichloromonofluoromethane as the foaming agent. By experimentation or otherwise, the proper amount of the mixture to expand into a solidified body to completely fill the hollow door structure is easily ascertainable. Immediately after pouring the foamable ⁴⁵ mixture into the outer door panel structure, the inner panel is positioned with the channel member in surface engagement with its side wall portions (or with the flange portions of the outer panel if the channel had been applied to the inner panel) and the inner panel braced or ⁵⁰ supported by applying thereto a back-up member which is secured against release by clamping means or the like. It is a feature of the invention that as the insulation mass develops and fills the hollow door, it envelops the outer wall of the channel member and grips the ribs or other ⁵⁵ keying devices. The solidified foam insulation thus securely locks the channel within the mass of insulation material and thereby holds the outer and inner panel । members in secure position relative to each other. After the completion of the insulation process, a door gasket : ⁶⁰ having a body portion arranged to seat frictionally with: in the channel structure may be readily applied by sim! pie insertion and without the use of fastening devices of any kind. It is apparent therefore that, because the chani . nel structure is securely held as an incident to manufac&gt; ⁶⁵ ture and the gasket is only frictionally held within the

3,137,900 INSULATED WALL AND METHOD OF MANUFACTURE

Richard J. Carbary, La Grange, III., assignor to General Electric Company, a corporation of New York

Filed Aug. 1, 1961, Ser. No. 128,536 6 Claims. (Cl. 20—35)

This invention relates to thermally insulated structures and the method of manufacture thereof, and it is of particular interest with respect to the manufacture of an insulated structure such as a refrigerator door or the like in which one portion may be of relatively good heatconducting material and a second portion may be of relatively poor heat-conducting material.

In refrigerator manufacture, for example, it is the practice to make the door of the cabinet by assembling two panels. The outer panel is usually of steel and provides the front and side walls. The inner panel, which may be formed by various manufacturing methods, is usually of plastic. This inner panel is exposed to the temperature of the interior of the cabinet, which may be from 60 to 100 degrees F. lower than the outside temperature to which the outer door panel is exposed; and to minimize heat flow from the outer to the inner panel, it is common to use low heat-conductivity members, known in the art as “breaker strips,” to join the respective outer and inner panels. To insure that the door seals snugly against the marginal walls of the cabinet, it is the usual practice to employ resilient gaskets adjacent the marginal walls of the door. With the new emphasis on door latches or door constructions which will open under the relatively light effort applied against the door from the inside-—that is, an effort which a trapped child could apply—the gaskets must be very “soft,” for there is no longer the action of a strong latch to pull the door home. Some manufacturers eliminate latches, and rely on magnetic gaskets which maintain the door in closed position by magnetic engagement with the adjacent cabinet walls.

Currently, almost all refrigerator door gaskets are secured to the door by screw-fastened devices. In manufacture this requires that a workman drive a multiplicity of screws, and an inspection procedure which, among other things, will determine whether or not the screws have been properly applied. When it is necessary for a serviceman to change a gasket in the field, as is sometimes required when after a period of use the soft gaskets take a set which permits air leakage into the cabinet, it is a complex and time-consuming job which is quite likely to arouse the ire of the customer, for his refrigerator must be out of service for an hour or more and the contents may spoil.

It is therefore a principal object of the invention to provide means which combines a low heat transfer breaker strip with 'structure which facilitates the installation of a gasket during manufacture and greatly expedites the removal and replacement of gaskets by servicemen in the field.

It is an object of the invention to provide a gasket mounting means within which a refrigerator door gasket or the like may be securely held by friction without the use of screws or adhesives.

It is a further object of the invention to provide a gasket mounting structure which is particularly adaptable

3,137,900 channel, there is no problem with respect to the removal and replacement of a gasket under field service conditions.

A further advantage of the gasket-receptive channel is that a body of spacer material may be placed between the inner base wall of the channel and the base of the gasket if it be necessary to cause an abnormal projection of the gasket from the channel in selected areas.

Other features and advantages of the invention will be understood from the following detailed description of presently preferred forms, read in connection with the accompanying drawings, in which:

FIG. 1 is an enlarged fragmentary section of a portion of a refrigerator door and a refrigerator cabinet, constructed according to the present invention and illustrating the use of a magnetic door gasket;

FIG. 2 is a fragmentary view of the assembled outer and inner panels with a channel member and gasket member of somewhat different construction;

FIG. 3 is a fragmentary plan view of a corner portion 20 of the door looking at the inside panel thereof showing portions of the channel members in position;

FIG. 4 is a fragmentary side sectional elevation of an inner door panel in which the gasket channel portion is integral with the door panel; and 25

FIG. 5 is a somewhat schematic cross sectional view of the outer and inner door panels assembled following the introduction of a charge of insulation material.

Referring now to FIGS. 1 and 2 a refrigerator door 1 comprises an outer panel 2 and an inner panel 3 assembled so as to define therebetween a hollow space completely occupied by a body of solidified foam-type insulation 4. Said foam may be of any of the well known polyurethane resins using trichloromonofluoromethane as the foaming agent. It will be noted that the outer panel 2 is a dish-like structure having a front wall 5, side walls 6 and a relatively short inwardly extending flange 7. It will be understood that the flange 7 is provided about each of the four sides of the panel 2.

The inner panel 3 may be of conventional shape as is now required for the mounting of door shelves (not shown) and the like but has an outwardly extending flat wall portion 8 about its four sides. As indicated in FIGS. 1 and 2, it will be understood that the dimensions of the inner door panel are such that when it is placed relative to the flanges of the outer door panel, a substantial gap will extend about the four wall portions 8 of the inner panel, and the present invention contemplates the bridging of this gap by means of a low thermoconductivity member which affords means for securing the respective panel members relative to the body of insulation material while providing for the easy insertion and removal of a door gasket.

For example, in FIG. 1 there is illustrated a channel structure 10 in which the channel opening faces upwardly, that is, toward the metal facing walls 12 of a refrigerator cabinet. Said walls are arranged to receive the edge walls of a plastic inner liner 13, as is conventional. The channel may be extruded from any of the commonly used materials such as rigid polyvinyl chloride, and in the FIG. 1 form is shaped to have an outwardly extending flange 14 which will be in overlapping relationship with the side wall 8 of the inner panel and the fork-like walls 15 which snugly receive the inner portion of the flange 7 of the outer panel. Ribs 16 of any suitable shape are provided on each of the outer wall portions of the channel. Interiorly of the channel, the walls are similarly formed with rib structures so as frictionally to grip the body portion of a gasket. For example, one wall may have a rather large radius curved rib 17 whereas the other wall may have the serrations 18. This configuration is by way of illustration only and is intended to typify a construction in which the channel readily receives a gasket while securing it against accidental outward displacement. 19 represents a resilient body of material between the gasket and channel, for a purpose later described.

The gasket 20 of FIG. 1 is of the well known magnetic type in which very flexible side walls 21 support a tubu5 lar structure 22 within which is located a continuous strip of magnetic material 23. As is well known, such magnets comprise a mass of magnetized iron particles contained within a plastic body. The main body portion 24 of the gasket is made compressible by means of the con10 tinuous longitudinal opening 25 therein, whereby the gasket will readily permit insertion within the channel 10. In channel members provided with longitudinal serrations 18, it may be advantageous to utilize a complementary serration 26 on the adjacent gasket body wall. It is 15 comtemplated that the opposite wall will be plain and yieldable to accommodate the rib 17 following gasket insertion. At the junction of the ribs 21 and gasket body 24, I provide the outwardly extending flexible wings 27 which will extend beyond the forked structure 15 of the channel 10 and also conceal the joint between the panel 3 and the channel 10.

In the embodiment of FIG. 2 the channel member 30 is arranged to have its forked walls 31 engage the side wall portions 8 of the inner panel and its outwardly extending flange 32 in an overlying relationship with respect to the flange 7 of the outer panel 2. In other respects the channel configuration may be similar to that illustrated in FIG. 1; that is, it may be provided with appropriate exterior and interior ribs for the purposes of keying with the insulation material and with the gasket. The FIG. 2 gasket 33 is typical of the “soft” non-magnetic types and has been illustrated as of the form described in Tarleton U.S. Patent 2,880,049, granted March 31, 1959, for “Refrigerator Cabinet Structure” and assigned to my present assignee. It may be noted in passing that the gasket illustrated in the said Tarleton patent is fastened to the door construction in accordance with the previous generally accepted practice, that is to say, by means of screw-fastened devices.

In FIG. 3 there is illustrated in top plan view, a channel 10 (or 30) to illustrate the inner rib 17 and inner serrations 18 and also to show the mitered joint arrangement of the channels at the corners of the refrigerator door. In FIG. 4 a plastic inner door panel 3α is pro45 vided with an integral channel member 10α of keystone shape. It will be noted that this channel portion has the outwardly extending flange 15α which overlies the flange 7 of the outer panel 2. Because of the keystone shape of the channel 10α, it will be unnecessary 50 to provide the interior or exterior ribs.

Referring now to FIG. 5, it will be assumed that the door panel 2 has been fitted with the channel 10 about its four sides. The outer panel is placed on the table ^anY suitable press, and into the basin-like structure ⁵⁵ formed by the outer door there has been poured a charge 37 of the foamable insulation-forming mixture. Immediately thereafter and before the foaming mixture has had an opportunity fully to rise within the door panel 2, ₆₀ the outer panel 3 is placed in position with its side wall portions 8 resting upon the outwardly extending flange 14 of the channel 10. It will be noted that the channel forms a good locating means for the door panel. Thereafter a back-up structure 38 is placed over the door and 65 ^an appropriate number of clamps 40 positioned and made secure by the dogs or equivalent 41. Ordinarily, to accommodate the mounting means for door shelves in the completed refrigerator door, the inner panel 3 will be provided with a suitable plurality of apertures 42 to ac70 commodate screws or other fastening devices for the shelf mounts. Said apertures provide an advantageous method of venting the interior of the door during the time when the foaming insulation is expanding to completely fill the door structure. Therefore, the back-up member 38 ⁷⁵ may have the illustrated cavities 43 enveloping the aper3,137,900 ⁵ tures 42 and communicating by way of passages 44 to a central venting passage 45.

As an alternate to the venting procedure, the rib portions 3Z&gt; of the door panel 3 (FIG. 2) may have therein strips 4α of compressible insulation material such as glass fibre, which will accommodate the ultimate expansion of the foam insulation 4.

It will be noted that in the channel arrangement of FIG. 1 the door panel 3 is not in fixed relationship to the channel 10 in the manner of the engagement of the outer panel flanges 7 with the forked wall 15. It may be advantageous therefore to provide at appropriate intervals about the inside surface of the door panel 3 the projecting knobs or elements 46 having external serrations or the like which will be gripped by the foamed insulation as it expands and sets. Thus, in the FIG. 1 form, the channel 10 is securely gripped by the foam insulation 4. The outer panel 2 is secured to the channel 10 by way of the engagement of the forked wall 15 with the flange 7. The panel 8 is securely locked in position by the configuration of the projections 46 and the envelopment thereof by the foam 4.

In the FIG. 2 channel embodiment the inner panel itself is gripped by the fork portion 31 of the channel, thereby making the knob-like projections 46 unnecessary. It will be that apparent that the outer panel 2 is so related to the channel 30, and the channel 30 so keyed within the insulation 4, as to make additional fastening means unnecessary for the outer door panel.

Similarly, it will be observed that in the integral structure of FIG. 4, the outer and inner panels will be securely held together by the solidified body of foam insulation.

Reverting to FIG. 1, the material 19 below the gasket body is illustrative of a resilient spacer strip which may be employed if it is desired to project the gasket more than normally beyond the flange 7 and inner panel 3. This may provide, for example, a convenient way to correct improperly functioning gaskets in field service calls. The material 19 will advantageously be in strip form, cut in the field to whatever length is necesary to accomplish the purpose.

While there has been described what is at present thought to be a preferred embodiment of the invention, it will be understood that it is intended to cover in the appended claims all modifications which fall within the true spirit and scope of the invention.