Sliding Door Construction

Abstract

A refrigerator door unit received in an opening in a refrigerator wall and adapted for horizontal movement therein to provide access to a refrigerator compartment. The door system comprises a unit frame and two parallel doors mounted for horizontal movement therein. The system is unique, in that, a complete thermal barrier is provided across the access opening. Such a barrier is accomplished by thermally insulated doors equipped with means to seal the space between the doors and by the unit frame which exposes no conductive path between the refrigerated interior of the compartment and the ambient outside air.

Description

BACKGROUND OF THE INVENTION

The technological development of the refrigeration arts has progressed steadily and numerous innovations have been conceived insofar as door structure, door hinge systems and the like are concerned. Likewise, the art relevant to sliding doors has progressed. As with other developments, the ultimate objective is to provide cheaper and more efficient equipment. In this regard, the advent of convenience stores and the like has brought about a tremendous surge in sales of cooler and freezer units utilizing door systems that permit visual observation of goods displayed therein and subsequent self-service selection by the consumer. The doors on these various units are thus subjected to a vast amount of use. As such, the refrigeration efficiency of the unit must be such that even under continuous use, the products displayed therein will remain at proper temperatures. Moreover, continued use by the customer or consumer invariably causes damage of varying degrees to the doors. The doors must thus be suitably designed to withstand as much abuse as possible and must be suitable for quick and easy installation and removal.

The operating efficiency of the refrigerator or freezer unit is of paramount importance. Conventional door systems presently being utilized in these environments possess conductive paths therethrough, between the refrigerated interior of the unit and ambient outside air. These thermal leaks cause condensation and/or fogging on the doors. In the event of fogging, where a door utilizing a transparent center panel is in use, the customer cannot visually inspect the goods through the door. Consequently the customer must open the door to inspect the goods and thereby expose the goods to warmer ambient air which of course must be then cooled to retain the goods at the proper temperature. The operating efficiency of the unit is thus reduced. Where condensation appears on the doors, the droplets continue to form until large enough to run down or drop off the doors onto the floor. The water surrounding the unit is thus unsightly and a safety hazard and must be removed by store personnel.

The construction of the refrigerator door, per se, is not a feature of this invention, but it is covered in our copending application, Ser. No. 40,204, filed concurrently herewith and entitled Refrigerator Door Structure. Such a door is, however, described herein and is claimed herein in the present environment in conjunction with the unit frame.

A further disadvantage of sliding doors presently in use and described in the prior art is the ability of the door to reclose. To ensure proper sealing engagement between the doors and the unit frame, a bias means is necessary to hold the door against the frame. Such means could be provided in one or more ways. First, the individual channel in which the door rides or the door-supporting trackway must be sloped in the direction of closing whereby once opened and released the door would return to a closed position by gravity. A second and probably better system would be the utilization of a spring means on the door which is lengthened during opening of the door and once the door is released seeks its original state, whereby the door is returned to the closed position. Inasmuch as doors of this type are subject to great and continued use, the spring means becomes less effective due to a stretching or permanent elongation of the spring.

The door system of the present invention has incorporated therewith improvements that overcome the above-described problems and disadvantages. Moreover, while the patented prior art does contain teachings analogous to the instant system, as exemplified by U.S. Pat. No. 3,177,989 to Di Chiaro; U.S. Pat. No. 3,418,755 to Di Chiaro; and U.S. Pat. No. 3,466,801 to Bohn, none of these patents individually or collectively teach or suggest the improved sliding door system of the present invention.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide an improved sliding door system for a refrigerator unit.

Another object of the present invention is to provide an improved refrigerator door system that provides a complete thermal break against thermal conductance from the interior of a refrigerated compartment to the ambient outside air.

Still further, another object of the present invention is to provide an improved refrigerator door system having automatic closing means associated therewith.

Generally speaking, the refrigerator door unit of the present invention is received in an opening in a refrigerator wall and adapted for horizontal movement therein to provide access to a refrigerator compartment, said door unit comprising a unit frame positioned in said opening in said wall and removably secured thereto, said unit frame comprising an inner rigid member having a low thermal conductance property and an outer rigid member snap fitted thereto; and two thermally insulated doors mounted within said opening, said doors being spacially separate and parallel, each of said doors being provided with a protuberance that extends across a space between the doors to said other door, said protuberances having low thermal conductance properties, said doors and said unit frame cooperating when said doors are in the closed position to provide a complete and continuous thermal barrier in said opening between said refrigerator compartment and ambient air outside said refrigerator unit.

More specifically, the door system of the present invention is equipped with a unit frame that extends around the periphery of the entire system. The unit frame is comprised of a rigid inner member that is manufactured from a material having a low thermal conductance property, such as a rigid vinyl. The inner rigid member is frictionally engaged with the refrigerator wall and has snap fitted thereto an rigid outer member, preferably a metal member. The outer member snap fits to the inner member and extends beyond the frame to provide an outer aesthetic border around the unit frame. In the sense of a horizontally moving door that is suspended from rollers, the unit frame would comprise two vertical and a lower horizontal section as previously described. An upper horizontal section of the frame would likewise be provided with a thermal break, but the structure of the upper section would differ from the others to receive the door suspension system. Wheels mounted to the top of the door would be suspended from a suitable rail in the upper portion of the frame. If, however, the doors are supported such that the doors rest in a trackway and are supported thereon, then the unit frame as described above would comprise two vertical and two horizontal sections virtually as described with the doors being mounted therein.

The door of the present invention must likewise be thermally insulated so as to prevent the existence of conductive paths therethrough, between ambient outer air and the cooler air within the refrigerated compartment. Likewise, since two doors are employed for the horizontal moving environment, it is necessary to have space between the doors to permit parallel movement of both doors. This space would normally permit a thermal leak. To obviate such a leak, the doors of the present invention are each equipped with protuberances that extend outwardly therefrom and engage the opposite door whereby a double seal is provided to insulate the space between the doors.

The automatic closing feature for the doors of the present invention includes a spring secured at one end to the door and at an opposite end to the door frame. Opening of the door elongates the spring and release of the door permits the spring to return to its original configuration, thus closing the door. In general, continued opening of these doors stretches the spring means and some of the elastic memory is lost, whereby proper closing of the door is not accomplished. The stretched spring must then be replaced. Accordingly, the present invention includes an improvement which comprises the presence of a spring adjuster, adjacent the door frame whereby after the spring has stretched through continued use, the slack may be taken up by the adjuster to revitalize the automatic closing means and realize continued proper closing.

Generally speaking therefore, the overall door system of the present invention presents a system for use with a refrigerator unit to, when both doors are closed, provide a complete barrier against conductance of heat therethrough, whereby condensation on the frame and the doors, per se, is avoided. In accomplishing this feat, poor thermal conductance materials are employed in the construction of the unit frame and the unit frame is produced without the use of extraneous fastening members. Instead, the components of the door frame snap fit together and the door frame, per se, is frictionally engaged with the refrigerator wall. Additionally, each edge of a door that comes in contact with the door frame is provided a resilient sealing member such that when the door is in the closed position an additional seal is provided around the edges thereof. Moreover, the automatic closing system for the instant doors alleviates the possibility of the door being inadvertently left open which would reduce the refrigeration efficiency of the refrigerator unit. Additionally, the adjustment means for the automatic closing means ensure a longer effective life for the spring means being utilized in the automatic closing means.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partial perspective view of the side of a refrigerator unit having incorporated therewith a door system according to the teachings of the present invention.

FIG. 2 is a side cross-sectional view of the door system of the present invention taken along lines II--II of FIG. 1.

FIG. 3 is a top cross-sectional view of the door system of the present invention taken along lines III--III of FIG. 1.

FIG. 4 is an enlarged cross-sectional view of one section of door frame as provided by the present invention.

FIG. 5 is a partial blown-up cross section taken from FIG. 2 and showing the relationship between doors for sealing the air space between the doors.

FIG. 6 is a cross-sectional view of the outer member of a door frame according to the teachings of the present invention.

FIG. 7 is a cross-sectional view of a rigid inner strip of a door frame according to the teachings of the present invention.

FIG. 8 is a top cross-sectional view of a door according to the teachings of the present invention and showing the automatic closing means associated therewith.

FIG. 9 is a plan view of the adjustment member for the automatic closing means of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to the figures, specific embodiments of the present invention will now be described.

FIG. 1 is a cutaway of a portion of a refrigerator unit showing the sliding door environment. FIG. 1 thus shown a portion of a front wall defined by two panels 10 and 10 of a refrigerator unit having an opening therein. The opening is filled with a unit frame generally indicated as 12 and two doors generally indicated as 20 mounted for horizontal movement therein. Opening of either door 20 will thus provide access to a refrigerated compartment within the refrigerator unit. Such a compartment may be provided with a plurality of horizontally disposed shelves (not shown) on which items are displayed for purchase.

The unit frame 12 is comprised of two vertical sections 14 and 16, a lower horizontal section 18 and an upper horizontal section 19. Historically, the sections used to make up the unit frame are metallic sections that are joined together by screws, bolts or the like, and little if any effort has been directed to the provision of a thermally insulated unit frame. The ordinary unit frame thus provides a conductive path through which a thermal leak occurs that causes condensation on the unit and also reduces the refrigeration efficiency of the unit.

The doors utilized in the sliding door system of the present invention are generally mounted in one of two ways. The doors may be suspended from rollers on trackways above the unit frame or the doors may be supported on rollers at the bottom of the door that are received in a recess in the bottom of the door. The particular means for mounting the doors within the present door system are not, however, crucial to the present invention. Accordingly, only the overhead roller support mounting means is illustrated.

Doors 20 as shown in FIG. 1 comprise a central panel 22 that is held and supported by a suitable door frame 24. Suitable handles 26 permit ease of opening and closing of doors 20.

Whereas different mounting means for doors 20 were discussed above, the unit frame 12 will naturally vary according to the particular mounting scheme. For instance, for an overhead suspension system as is illustrated in FIG. 2, the two vertical sections and the lower horizontal section of the unit frame 12 would be of same construction while the overhead horizontal section would be modified to accept the trackways and roller systems for supporting the doors. On the other hand, for a mounting scheme where the doors are supported by rollers in the bottom of the door, the two vertical sections of unit frame 12 and the upper horizontal section of unit frame 12 would be of same construction while the bottom horizontal section would be modified to accept the door support system. In any situation, however, the teachings of the present invention may be utilized to modify the particular sections of the unit frame so as to achieve the complete thermal break that separates the refrigerated compartment from the ambient air surrounding the refrigerator unit.

FIG. 2 shows a side cross-sectional view of two doors mounted for horizontal movement according to the teachings of the present invention. In FIG. 2, the length of the doors has been cut so as to reduce the size of the figure and add to the ease of understanding of the parts thereof. An opening is produced along front wall 10 of the refrigerator unit to permit access to a refrigerated compartment within the unit. A lower horizontal section 18 of the unit frame 12 is comprised of a rigid inner member 30 having a rigid outer member 40 snap fitted thereto as may best be seen in FIGS. 2 and 4. Rigid inner member 30 is produced of a material having poor thermal conductance properties so as to provide a thermal break between the refrigerated compartment and the outside of the unit. Member 30 is comprised of a base 31 having protrusions 32, 33, 34, and 35 extending downwardly therefrom. Protrusion 32 is a "U"-shaped protrusion having only one leg 32' attached to base 31. The other leg 32" of the U does not reach back to base 31 and provides a space for insertion of a portion of wall 10. Wall 10 thus is frictionally engaged between base 31 and the short leg 32" of protrusion 32. Protrusion 33 is "L"-shaped having a leg 33' extending rearwardly in the direction of the refrigerated compartment. At the base of leg 33', a slot 33" is provided, the purpose of which will be immediately described. Protrusion 34 extends downwardly from base 31 and terminates adjacent the upper edge of slot 33" of protrusion 33. Protrusion 35 likewise extends downwardly, but in an arcuate manner, the purpose of which will be immediately explained. A section of internal wall 10' extends forwardly along inner member 30, and inner member 30 is secured thereto by protrusions 33, 34, and 35. The forward portion of wall 10' is received within slot 33" of protrusion 33, is engaged by the terminal end of protrusion 34 and by arcuate protrusion 35. Inner member 30 of unit frame 12 is thus secured to wall section 10' by a frictional connection between wall 10' and slot 33'. Moreover, the arcuate protrusion 35 when engaged by wall section 10' is forced upwardly, whereby a resilient memory in protrusion 35 causes protrusion 35 to apply positive pressure to wall 10' to assist in securing same to inner member 30. Also, the resilience of arcuate protrusion 35 assures a good seal against wall 10' even if wall 10' is uneven.

The forward end of inner member 30 is cut down so as to receive rigid outer member 40 in snap fitting engagement. At the beginning of the cutaway portion of base 31 is a groove 36 having a shoulder 36' for receiving a portion of outer member 40. At the outermost end of inner member 30, the cutaway portion of base 31 presents a shoulder 37 for further engagement with outer member 40. Atop base 31 of inner member 30 are two channel defining members 38 and 39 and between channel defining members 38 and 39 is a slot 41 having lips 41' extending partially thereacross. A sealing gasket 60 fits into slot 41 and is held therein by a barbed protrusion 61 which engages lips 41' of slot 41. Sealing gasket 60 has two deformable door contact members 62 that define a space 63 therebetween and flex with the force of door 20 to provide a good thermal seal against door 20.

Referring specifically to FIG. 4, rigid outer member 40 comprises a body 42 having a tee 43 at its outer end. Tee 43 has extending rearwardly thereof locking member 44 which passes between wall 10 (see FIG. 2) and shoulder 37 of inner member 30 and engages the underside of shoulder 37 in snap fitting relationship. The rear end of body 42 of outer member 40 is cutaway at 42' and has a shouldered terminal end 44'. End 44' passes into slot 36 of inner member 30 and engages shoulder 36' therein to be retained in snap fitting relationship. The upper portion 43' of tee 43 coacts with channel defining member 38 to form a door channel therebetween. Body 42 of outer member 40 on its upper side has a slot 45 which has lips 45' extending partially thereacross. A further sealing gasket 60 is held therein by a barbed protrusion 61 and deformable members 62 are presented for sealing engagement with a door 20.

Referring back to FIG. 2, two doors 20 are shown resting on sealing gaskets 60. Doors 20 are suspended from rollers 70 by struts 75 which are associated therewith and are also secured in any convenient manner to the top of door 20. The upper portion of unit frame 12 when the doors are suspended from rollers thus comprises a track support 50 that may be any desired material and is secured to top wall 12 of the refrigerator unit by any suitable means, such as bolts 14'. Track support 50 has two legs 52 and 54 depending downwardly therefrom. Legs 52 and 54 have transverse sections 53 and 55 respectively, each of which terminates as beads 56 and 57 which serve as the trackways for the door rollers 70. Additionally, support leg 54 has a slotted lower end 58 with a slot 59 that receives a sealing gasket 80.

A rigid strip 90 is positioned between track support 50 and front wall 10. Strip 90 is manufactured from a material having low thermal conductance properties and has a leg 91 at an upper end that extends around track support 50 where it is sandwiched between track support 50 and upper wall 12. The opposite end 92 of strip 90 terminates as a U-shaped member that extends around an in-turned portion 10" of wall 10 and engages an outer frame strip 40'. Outer frame strip 40' has a leg 42" extending rearwardly thereof, said leg having a lug 42" that is received within a like-shaped depression in U 92 of strip 90 so as to be securely held thereby.

Rearwardly of track support 50 is further rigid strip 95 of a material having low thermal conductance properties. Strip 95 has an upper end 96 that is secured between track support 50 and upper wall 12 by bolt 14. Strip 95 fits against track support 50 and depends downwardly therefrom to form a wall engaging channel 97. Wall 10' is received in channel 97 so as to produce a solid connection between strip 95 and wall 10'. The lower end 98 of strip 95 has a slot 99 with lips 99' extending partially thereacross. Slot 99 receives a barbed protrusion 81 of a sealing gasket 80 that serves to seal the upper portion of a door 20 against a thermal leak.

FIG. 3 shows a top cross section of two doors mounted for sliding movement according to the teachings of the present invention. Thus a front wall 10 of a refrigerator unit is shown having an access opening to a refrigerated compartment behind the door system. The two vertical sections of the unit frame are thus shown to comprise a rigid inner member 30 in frictional engagement with panels 10 and 10' and a rigid outer member 40 snap fitted to inner member 30. Door channel defining members 38 and 39 are likewise shown in conjunction with member 43' of outer member 40 to define the two parallel channels in which the doors move. Further, on each sealing end of a particular channel, a sealing gasket 60 is secured to the inner members 30. It is noted that for the vertical sections of the unit frame, a sealing gasket 60 is not provided on the end of the channel where the door 20 does not come into sealing engagement with the particular section of the unit frame. Instead, a button 65 is secured within the slot that would accept the sealing gasket. An air space 200 exists between the two doors 20 that are mounted for parallel movement. In order to provide a complete thermal barrier, it is thus necessary to seal the area between the doors so as to insulate air space 200. Such a seal is produced as shown in FIG. 3, and the features of the doors 20 that afford such a seal will now be described with reference to FIGS. 5, 6, and 7.

In FIG. 5, a portion of the adjacent ends of the two mounted doors as displayed in FIG. 3 is shown enlarged. Each door in FIG. 5 comprises a panel 22 which preferably is a transparent multipane glass unit that affords the proper thermal insulation while permitting visual inspection of the goods behind the doors. Each panel 22 is surrounded and held by a door frame generally indicated as 24. Door frame 24 comprises a rigid outer member 40" which may be a metallic member and is preferably stainless steel or aluminum. Outer member 40" assumes a U-shaped configuration having a long leg 42', base 44' and short angularly disposed leg 46. A rigid inner member 50' of a material having poor thermal conductance properties is snap fitted to outer member 40" so as to sandwich panel 22 therebetween. Inner member 50' comprises a shoulder 52', an inwardly protruding barb 54', and a U-shaped end 56 having an inner leg 57'. Shoulder 52' of member 50' mates with base 44' of outer member 40" while barbed protrusion 54' engages angularly disposed leg 46 of member 40" so as to unite members 40" and 50'. Inner leg 57' of U-shaped end 56 resides adjacent one side of panel 22 so as to hold panel 22 between member 50' and leg 42 of member 40". Preferably member 50' when constructed possesses a slight curvature as shown in FIG. 7, such that, when snap fitted onto member 40" with a panel 22 therebetween, member 50' straightens out while retaining the memory of the curvature so as to continuously apply a positive pressure against panel 22.

The door frame generally described above contains no separate fastening members, and thus since internal member 50' is exposed to the refrigerated compartment, while member 40" is not, no thermal conductive path is present through which heat may be lost and by which condensation may occur insofar as the door, per se, is concerned. Since, however, as mentioned earlier there is an air space 200 between the parallel mounted doors 20, it is necessary to seal this area so as to provide a complete thermal barrier between the refrigerated compartment and ambient outside air. Referring to FIGS. 5 and 6, a rigid outer member 40" is shown having a sealing strip 48 attached thereto. Outer member 40" is provided with a slot 47 having lips 47' extending partially thereacross. Sealing strip 48 possesses a barbed protrusion 48' which passes between lips 47' of slot 47 and is secured therein. When the two doors 20 are mounted in parallel relation in the door system of the present invention, sealing strip 48 extends outwardly from outer member 40" of the inner door 20 of the system where it engages the inner member 50' and/or panel 22 of the outer door 20 of the door system. In so doing, one end of air space 200 is sealed, since sealing strip 48 is produced from a material having low thermal conductance properties. Preferably, sealing strip 48 extends across space 200 all the way to the panel 22 of the parallel door 20, whereby regardless of the position of the two doors 20, sealing strip 48 would always seal one end of air space 200.

FIGS. 5 and 7 show rigid inner member 50' which has adjacent shoulder 52, an angular protrusion 54. Angular protrusion 54 extends outwardly from member 50" for a distance sufficient to reach across air space 200 and to engage panel 22 of the inner door 20. As with sealing strip 48, angular protrusion 54 of inner member 50" remains in contact with panel 22 of inner door 20 in any position so as to seal that particular end of the air space 200.

As mentioned earlier, the doors utilized in the sliding door system of the present invention have an automatic closing feature. This feature is best illustrated in FIGS. 2, 8, and 9. FIG. 8 shows a top cross section of a door 20 positioned within a unit frame 12 of a door system according to the present invention. Door 20 is shown suspended from a pair of rollers 70 that ride on a trackway 56. Each roller 70 is secured to a strut 75 by a suitable pin 76 and the roller 70, on the end of the door away from the door frame in the closed position, has attached thereto at member 75 a spring 77 that is preferably a coiled spring. Spring 77 is associated with wall 10 at an opposite end thereof. Accordingly, if door 20 as shown in FIG. 8 is moved in the direction of the arrow, spring 77 will expand along with movement of door 20. When, however, door 20 is released, spring 77 will seek its original coiled position and in so doing will cause door 20 to move in a direction opposite to the direction of the arrow and to move into sealing engagement with unit frame 12. Continuous operation of door 20 will normally cause spring 77 to stretch and hence lose some of its memory. A spring adjustment bar 100 is thus provided to take up the amount that spring 77 may have stretched. Adjustment bar 100 has an L-shaped flange 102 at the end thereof and is secured to wall 10 through flange 102. Along the length of adjustment bar 100 are a plurality of angular slots 104. During initial installation of door 20, spring 77 would be attached to adjustment bar 100 at the first or the closest slot 104 to spring 77. As use of door 20 continues and spring 77 begins to stretch, spring 77 may be moved along the successive slots 104 of adjustment bar 100 to continuously provide proper tension in spring 77 and thereby increase the useful life thereof. Adjustment of spring 77 will thus ensure that door 20 will come to rest in sealing engagement against gasket 60 so as to provide a complete thermal barrier between the refrigerated compartment and the ambient air.

For doors supported from underneath for horizontal movement, unit frame 12 would have like vertical and upper horizontal sections while the lower horizontal section would be modified. Such modification to the lower horizontal section would primarily involve only the provision of a bearing surface on which the door rollers would ride.

Having particularly described the present invention, one skilled in the art may readily arrive at modifications and adaptations thereto without departing from the spirit of the invention. Accordingly, the scope of the invention should be governed by the claims appended hereto.

Claims

What is claimed is:

1. A refrigerator door unit received in an opening in a double-panel refrigerator wall and adapted for movement for providing access to a refrigerator compartment comprising: a unit frame positioned in said wall and removably secured thereto, said unit frame including a low thermal conductive member, said member including an elongated base portion, an L-shaped protrusion carried adjacent one end of said base portion defining a slot, one panel of said refrigerator wall having a planar portion extending into said slot and abutting against said L-shaped protrusion, a U-shaped protrusion having a leg terminating short of said base portion and facing said other end of said base portion, another panel of said refrigerator wall having a flange portion adjacent an edge extending between said leg of said U-shaped protrusion and said base portion, said member having spaced protrusions on the opposite side of said base portion from said L-shaped and U-shaped protrusions defining slots, a pair of thermally insulated doors mounted in said slots for horizontal movement, and said doors being provided with a protuberance carried between said doors having low thermal conductance properties providing a thermal barrier between said doors.

2. The refrigerator door unit set forth in claim 1 further comprising: a pair of sealing gaskets carried in said slots between said base portion and an edge of said insulated doors, and each of said sealing gaskets having two spaced deformable door contact members defining a space therebetween for defining a thermal seal between said base portions and said doors.

3. The refrigerator door unit as defined in claim 1, wherein the unit frame comprises two vertical sections, a lower horizontal section and an upper section area where said doors are suspended on rollers, said vertical and horizontal sections including said low thermal conductive member, and said upper area has depending therefrom and in engagement with each door, a thermal seal.