Refrigerator Cabinet Structure And Its Manufacture

Abstract

In the manufacture of refrigerator cabinets of the dual compartment type, using vacuum forming techniques to mold an integrally formed double cavity liner, desired communicating fluid passages are formed between compartments, through confronting liner walls of adjacent compartment sections. While the liners are still in a pliable state, small sections of confronting liner walls at locations where passages are desired, are moved, with relation to one another, toward and into abutting engagement. The liners are then allowed to cool, followed by piercing the engaged liner wall sections to form the desired communicating passages.

Description

CROSS REFERENCE TO RELATED DISCLOSURE

This invention, in certain aspects thereof, is briefly described in the copending disclosure of Norman F. Houghton, Ser. No. 235,968, now U.S. Pat. No. 3,781,394, filed Mar. 20, 1972, entitled "Method and Apparatus for Forming Articles from Plastic Sheet Material," and assigned to the assignee of the present invention. Additionally, certain of the mold manipulating techniques hereof are within the purview of the claims of the aforesaid pending disclosure, and of Houghton, Ser. No. 73,761, now U.S. Pat. No. 3,709,968, filed Sept. 21, 1970, and also assigned to the assignee of the present invention.

BACKGROUND OF THE INVENTION

This invention relates to refrigerator cabinet construction, and particularly to the formation of communicating passages between adjacent storage compartments defined by molded thermoplastic liner sections.

In a dual compartment refrigerator, of one well known type, a refrigeration coil is positioned in one of two insulated compartments having steel liners, communicating air passages are formed between the compartments, and a fan is positioned to circulate air between the compartments to cool the same to predetermined desired temperatures. However, if the liners of such a refrigerator are of the molded plastic type, and the insulation is molded therebetween and between the liner and the outer shell, difficulties are encountered in arriving at a suitable and economical means for forming the air passages.

I therefore propose as a primary objective of my invention a novel method for forming communicating passages of the aforesaid type, which method is carried out in the liner molding operation.

It is a further objective of my invention to form communicating fluid passages between adjacent liners by utilizing the liner material itself to define such passages.

In accordance with other objectives I have been able to optimize the thickness of insulation surrounding various parts of the liners, and greatly to simplify the problem of shelf support while virtually eliminating the need for providing holes through the liner walls.

SUMMARY OF THE INVENTION

In achievement of the foregoing as well as other objectives, the invention contemplates a novel method for molding a pair of adjacent walled cavities as one integral structure of thermoplastic material, and for defining fluid passages therebetween. In the practice of this method, I utilize the steps of heating said walled structures to soften the same, forming said softened structures over mold means including protrusions extendable into the structure a distance sufficient to cause predetermined areas of the softened thermoplastic material to engage one another, and then piercing the engaged areas to form the passages. The invention further contemplates novel features of construction of such walled structures, including passages made according to the above described method and novel wall configuration.

The manner in which the foregoing as well as other objectives and advantages of the invention may best be achieved will be understood from a consideration of the following description, taken in light of the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is an elevational showing of refrigerator cabinet structure of one type embodying a pair of compartment liners made in accordance with the invention, and with the doors removed for convenience of illustration;

FIG. 2 is a sectional showing of the cabinet structure taken generally along the line indicated by arrows 2--2 applied to FIG. 1;

FIG. 3 is a perspective showing of a portion of the refrigerator structure seen in FIGS. 1 and 2, illustrating the inner passages thereof made in accordance with the method contemplated by the present invention;

FIG. 4 is a sectional-elevational view of mold apparatus for fabricating the compartment liners of the cabinet seen in FIGS. 1 to 3, and in accordance with the method contemplated by the present invention;

FIGS. 5, 6 and 7 are further showings of apparatus seen in FIG. 4, and illustrating operational features thereof;

FIG. 8 is an elevational showing of refrigerator cabinet construction of another type and made in accordance with the invention, the cabinet being shown with the door removed;

FIG. 9 is a sectional showing of the cabinet seen in FIG. 8, the view being taken generally along the line indicated by arrows 9--9 applied to FIG. 8.

FIG. 10 is a showing of apparatus similar to that seen in FIGS. 4 to 7, and illustrating method steps used in the fabrication of the liner portion of the apparatus seen in FIGS. 8 and 9, as it would be seen in section along the lines indicated by arrows 10--10 applied to FIG. 8.

FIGS. 11 and 12 are illustrations of further apparatus used in the fabrication of the above mentioned liners.

DESCRIPTION OF THE PREFERRED PRACTICE AND EMBODIMENTS OF THE INVENTION

With reference to FIGS. 1 and 2, the illustrated refrigerator cabinet 10 has a pair of compartments having unidirectionally presented openings, and defined by a pair of liner sections 11 and 12. The liner sections are made of thermoplastic material, and, in accordance with the general teaching of the Houghton inventions, are molded as an integral structure from a single flat sheet of such material. Thermal insulation designated generally by the numeral 13, and which may for example be of the foam type, fills the spaces between the confronting walls of liner sections 11 and 12, and between the outer walls of the same sections and the walls of outer shell 14 of cabinet 10. It will be understood, of course, that other well known suitable types of thermal insulation may be used.

The refrigerating unit is conventional, comprising a compressor 15, condenser 16, and an evaporator 17 connected in the usual series flow circuit by suitable conduit means (not shown). Evaporator 17 is conveniently located in the recessed portion 21 of upper liner section 11, and a partition 22 includes a horizontal section that extends over the recess and the evaporator. The horizontal section of partition 22 is provided with front air passages 23, and a vertical section 22a of the partition is spaced from the top and rear walls of liner section 11 as shown. Air moved by a blower 24 disposed in the rear, scroll shaped portion 20 of recess 21 is caused to flow into the freezer storage compartment defined by liner section 11, through the space between the liner and partition 22a, whence it returns to the region of evaporator 17 through front passages 23. The lower food storage compartment, defined by liner section 12, is cooled by air caused to move from the compartment through passages 25, over evaporator 17, thence back into the compartment through a passage 30 extending between the wall of scroll 20 and the upper horizontal wall of liner 12. Recess 21 includes wall portions 11a, 11b that are set in a predetermined distance which effectively provides a thickened insulation section in the region of evaporator 17, thereby improving the thermal performance of the refrigerator. Recess 21 also serves as a drain trough or sump for the evaporator, and a drain opening may be provided in said sump by molding or by separate installation.

The method contemplated by this invention readily accommodates formation of the communicating air passages 25 and 30 (see also FIG. 3) between the upper and lower refrigerator compartments, and which passages accommodate the above described air movement.

In carrying out the method contemplated by the invention, use is made of apparatus of the general type disclosed and claimed in the referenced copending applications. Such apparatus includes, and first with reference to FIG. 4, an open top, generally box-shaped chamber 26 having a pair of sub-sections 27 and 28, each separated from the other by a partition 29, and each ported at 31 and 32, respectively, to suitable vacuum producing mechanism of conventional design (not shown). A clamping ring 33 closely surrounds the upper rim of vacuum chamber 26, and is constructed and arranged to clamp in place a heat-softened sheet of thermoplastic material M that has been urged by an assist plug 35 onto a pair of vented mold members 37 and 38 shaped in correspondence with the shape of the interior of the food compartment liners.

Although the molding apparatus used in this invention has in common with the referenced disclosures the feature of relative pivotation between mold members 37 and 38, that feature need not be described herein for an understanding of the present invention. Only those common features that also form part of the present invention will be described.

The left-hand mold 37 includes an auxiliary mold section 42 that is extensible from the retracted position thereof illustrated in FIGS. 4 and 7 to the extended positions illustrated in FIGS. 5 and 6. In especial accordance with the invention, and for reasons that will be more fully appreciated from what follows, confronting spaced surface 59 and protrusions 60 are provided on molds 37 and 38, respectively.

Movements of auxiliary mold section 42 are affored by runners 44 on mold 37 slidably interengaged with corresponding grooves (not shown) on base portion 42a of the auxiliary mold section. Means for moving auxiliary mold section 42 includes a pair of links 46, only one of which is shown, each pinned to the mold section at 47 and to a pair of spaced bell cranks 48 that are pivoted at 49 to mold 37. Bell cranks 48, only one of which is illustrated for the sake of convenience, further are pinned to the piston rod of a pneumatic cylinder 50 pivoted at 52 to mold 37. The construction and arrangement is such that extension of piston rod 51 will rock crank 48 about its pivot 49 in a counterclockwise direction to move link 46 to the left and retract auxiliary mold section 42 to the position shown in FIGS. 4 and 7. Conversely, retraction of rod 51 rocks crank 48 about pivot 49 in a clockwise direction, moving link 46 to the right and extending mold section 42 to the position shown in FIGS. 5 and 6. As will be appreciated from FIG. 5, auxiliary mold section 42 is projected into engagement with that portion of sheet M that extends over left-hand mold 37, after the portion of the same sheet M extending over the right-hand mold 38 has been vacuum-formed over the latter mold, and its protrusion 60, by drawing a vacuum in chamber 28 through port 32. Projection of auxiliary mold section 42 to its fully extended position causes regions of the heat-softened sheet overlying surfaces 59 and protrusions 60 to engage and thereafter permanently adhere to one another.

In further particular accordance with the invention, a second extensible and retractible auxiliary mold member 61 is carried by mold section 38, and provides, in its extended position seen in FIGS. 5 and 6, for molding the air passage means 30 seen in FIGS. 2 and 3. Mold member 61 is generally retangular in cross section and is slidable from retracted positions shown in FIGS. 4 and 7 through suitable aperture means (not shown) within the wall of mold member 38. The inner, or right-hand, end of mold member 61 is carried by rod 62 of a pneumatic cylinder 63 mounted within mold member 38. The construction and arrangement is such that operation of rod 62 to extended position moves mold member 61 to its extended position (FIGS. 5 and 6). Conversely, operation to retract rod 62 also retracts mold member 62 (FIGS. 4 and 7).

Considering in detail the preferred sequence of operation of the mold members, and with reference to FIG. 4, heat softened sheet M is urged onto molds 37 and 38 by movement of assist plug 35 to the position shown, and while auxiliary mold sections 42 and 61 are in their retracted positions.

Assist plug 35 is then moved away from and clear of the molds to the position shown in FIG. 5. Auxiliary mold section 61 is then extended, urging its confronting portion of flat overlying sheet M into engagement with a corresponding portion of the same sheet overlying auxiliary mold section 42. This is followed by drawing a vacuum in chamber 28 by way of port 32, whereupon the right-hand portion of heat softened sheet M is caused to conform to mold member 38 and its extended auxiliary section 61.

With reference to FIG. 6, and considering the molding sequence in further detail, a vacuum is drawn in left-hand chamber 27 by way of port 31, while auxiliary mold section 42 is extended. The portion of sheet M overlying mold 37 and its auxiliary section 42 accordingly is drawn into conformity with the latter and portions of sheet M overlying surface 59 and confronting protrusions 60 engage and adhere to one another.

With reference to FIG. 7, auxiliary mold sections 42 and 61 are then moved from extended to retracted positions, and the liner sections molded from sheet M are ready for stripping as a unit from the molds.

It should be understood that while auxiliary mold section 61 is shown as two-dimensional, it will have a cross sectional dimension corresponding to that of air passage 30 as best seen in FIG. 3.

The regions of adherence of the above described molded liner sections are then pierced in a suitable manner, for example by punching as is shown somewhat diagrammatically in FIGS. 11 and 12. Conveniently, and by way of illustration, suitable apparatus may include a punch 64 and die 65 of desired cross-sectional shape and operable to remove liner sections 11c, 12a in completion of air passage 30. It will be understood that passages 25 are completed in the same manner, using a similar punch of suitable shape. As a result of the punching operation, there are formed lined, generally tubular, fluid passages or ducts 25 and 30 that are sealed with respect to later provided insulation 13 through which the ducts pass.

It will be further appreciated from a consideration of FIGS. 8, 9, and 10 that the invention lends itself to fabrication of air passage means in refrigerator cabinet structure 70 of the side-by-side type. With more detailed reference to FIG. 8, cabinet 70 has a pair of compartments having unidirectionally presented openings, and defined by a pair of liner sections 71 and 72. The liner sections are made of thermoplastic material, and, in especial accordance with the invention, are molded as an integral structure from a single flat sheet of such material. Thermal insulation designated generally by the numeral 73 fills the spaces between the confronting walls of liner sections 71 and 72, and between the outer walls of the same sections and the walls of the outer shell 74 of cabinet 70.

The refrigerating unit is conventional, comprising a compressor 75, a condensor (not shown) and an evaporator 77 connected in the usual series flow circuit by suitable conduit means. Evaporator 77 is conveniently located in the lower rear region of left-hand liner section 71, and a vertical partition 78 includes a lower section that extends over the evaporator and an upper section that extends over a fan 80. The upper section of partition 78 is provided with air grilles 79 over the fan 80.

Air moved by fan 80 is caused to flow through grilles 79 into the freezer storage compartment defined by liner section 71, through the space between the liner and the lower section of partition 78, thence returning to the region of evaporator 77. The right-hand food storage compartment, defined by liner section 72, is cooled by air caused to move from the compartment through lower passage 81, over evaporator 77, and thence back into the compartment through an upper passage 82 extending between the compartments.

As will be understood from FIG. 10, the method contemplated by the invention readily accommodates formation of the communicating air passages 82 and 81 between the side-by-side refrigerator compartments, and which passages accommodate the above described air movement. The method is carried out using apparatus similar to that used in forming liners 11 and 12, as explained in connection with FIGS. 3, 4, 5 and 6. Apparatus includes vacuum chambers 83, 83a ported at 84, 84a to vacuum producing devices. A clamping ring 85 is positioned to clamp the heat-softened sheet 86 that has been urged by an assist plug (not shown) onto a pair of vented, pivotally mounted mold members 87 and 88 shaped in correspondence with the shape of the interior of the desired food compartment liners.

The right-hand mold member 88 includes a pair of auxiliary mold sections 89 and 90, of generally elongate and generally circular cross section, respectively, which are mounted for movement from retracted positions to extended positions as shown in FIG. 10. Movements of mold sections 89 and 90 are provided by pneumatic cylinders 91 and 92, respectively.

In forming liners 71 and 72 a heat softened sheet 86 is urged onto mold members 87 and 88, and a vacuum drawn through port 84 to conform sheet 86 with mold member 87. Auxiliary mold sections 89 and 90 are then moved to the illustrated extended position, and a vacuum is drawn through port 84a, causing sheet 86 to conform with mold member 88 and its auxiliary mold sections 89 and 90. After a period of cooling, mold sections 89 and 90 are moved to retracted position, and the integrally formed liner sections and interconnecting air passages are removed from the mold members.

The formed air passages are then punched through, in accordance with the showing of FIGS. 11 and 12.

A further feature of the invention is that the method contemplated thereby makes possible the molding two liner compartments 71 and 72 of various relative sizes and shapes. For example, and with reference to FIG. 8, the lower side walls of left-hand compartment liner 71 are formed inwardly as seen at 71a and 71b and thus accommodate thickened insulated wall sections to either side of the vertically extending evaporator coil 77 positioned against the lower rear wall of liner 71. Below the evaporator coil 77, a drain trough 71c is molded into a lower rear section of the liner 71, using auxiliary mold means of the type used to form recess 21 in FIG. 3.

A number of advantages derive from both embodiments of the disclosed invention, in that two separate compartments, and interconnecting air passages, are integrally connected to accommodate their installation as a unit in the outer shell of a refrigerator. Further, by way of advantage, one compartment is very accurately registered with respect to the other so that predictable temperature differentials can be maintained therebetween, with resultant improvements in operating performance. Further control of temperatures is achieved through selectivity of insulation thickness (see 11a, 11b, FIG. 3, and 71a, 71b, FIGS. 8-10) in the region of the evaporator, which thickness may be selectively varied simply by changing the contours of the molds in the desired regions. Still further, condensate drain troughs (see 21, FIG. 3, and 71c, FIGS. 8, 9), shelf supports (see 71d, FIGS. 8, 9) and the like may be formed by appropriately shaping surfaces of the molds.

Claims

I claim:

1. A refrigerator including: a unitary liner having wall sections defining first and second compartments, a wall section defining said first compartment being disposed in confronting spaced relation to a wall section defining said second compartment; cooling coil means in said first compartment; drain trough means disposed below said cooling coil means, said drain trough means being integrally molded with a first compartment-defining wall section of said unitary liner; passage means extending between said compartments, said passage means being defined by integrally formed tubular portions of at least one of said confronting spaced wall sections, said tubular portions extending between and having open ends each communicating with a corresponding one of said compartments; fan means for circulating air through said passage means and over said cooling coil means to cool said second compartment; and inwardly spaced molded portions of the liner wall sections defining said first compartment, said portions accommodating provision of relatively thickened insulated regions adjacent said cooling coil means.

2. A refrigerator including: a unitary liner molded from thermoplastic material and having walls defining first and second compartments, one wall of one compartment being disposed in confronting spaced relationship to a wall of the other compartment; cooling coil means in said first compartment; inwardly spaced molded wall sections of said first liner, which sections accommodate provision of relatively thickened insulated regions adjacent said cooling coil means; passage means extending between said compartments, said passage means being defined by integrally formed tubular portions of at least one of said confronting spaced walls, said tubular portions extending between and having open ends each communicating with the interior of a corresponding one of said compartments; and fan means for circulating air through said passage means and over said cooling coil means to cool said second compartment.