CA1294139C - Appliance door having stiffened inner panel with shelves and method of forming - Google Patents

Abstract

APPLIANCE DOOR HAVING STIFFENED INNER PANEL
WITH SHELVES AND METHOD OF FORMING
ABSTRACT OF THE DISCLOSURE

A refrigerator door has its plastic inner panel, which has a plurality of container supporting shelves extending therefrom, stiffened through forming integral vertical stringers adjacent each other across substantially the entire width of the surface of the inner panel between the shelves. Gussets extend from one end of each of the integral stringers into one of the upper and lower surfaces of each adjacent shelf. The integral stringers are V-shaped or U-shaped in cross section. The gussets are V-shaped when the integral stringers are V-shaped and may be V-shaped or U-shaped when the integral stringers are U-shaped. The integral stringers stiffen the entire door without adding material and control the stiffness through the cross sectional moment of inertia of each of the integral stringers. When there is a lack of space beneath the bottom shelf, the gussets cannot be employed, but a shadow line is used to increase the moment of inertia.
The integral stringers have an aesthetic pattern in either the V-shaped or U-shaped configuration.

Description

~t'~ 311~3 APPLIANCE DOOR HAVING STIFFENED INNER PANEL
WITEI SHELVES AND METHOD OF FORMING

FIEL~J OF THE INVENTION
This invention relates to an appliance door having container supporting shelves on an inner panel and a method of forming and, more particular:Ly, to a sti~fening arrangement for providing rigidity to an inner panel of an appliance door having container supporting shelves and a method of formingO
BACKGROUND OF THE INVENTION
In a refrigerator door ~ormed of a metallic outer panel connected to a plastic inner panel with thermal insulating foam means therebetween, the smooth surface of the inner panel has shelves ~ormed integral therewith to accommodate containers for support. This has enabled containers such as bottles, for example, in particular to be stored on the shelves of the inner panel of the door.
However, the size o~ the shelves has been limited because ths load that the inner panel was capable of supporting has been dependent on the thickness of the inner panel~ The load carrying capability of the inner panel has been determined by peak stresses to which the inner panel is sub~ected ~or a speci~ic thickness O e the innsr panel.
To store larger size aontainers on the shelves of the inner panel o~ the re~rigerator door, it has been necessary to increase the thickness of the inner panel until the door is sufficiently rigid. However, this has substantially increased the material cost 3~
9D-HR~16771 when it is desired to support larger size containers.
Thus, the cost of the plastic of the inner panel has limited the maximum thickness at which the inner panel can economically be made. As a result, the size 5 of the shelves has been limited for most refrigerators so that they have not been able to accommodate relatively heavy containers.
The present invention satisfactorily solves this problem through having the inner panel of the refrigerator door capable of supporting relatively large leads in comparison with presently available inner panels of refrigerator doors while still forming the innex panel of the same material. Additionally, the thickness o~ the inner panel can be reduced about forty per cent for the same load when using the inner panel of the present invention so that significant savings in material costs are obtained while still being able to support greater loads on the shelves of the inner panel than presently available refrigerator doors.
The thickness of the inner panel of the door of the present invention is substantially reduced while accommodating larger loads through controlling the stif~ness of the door by forming inteyral stringers of a V-shaped or U-shaped configuration between the shelves o~ the inner panel. Each of these stringers has a cross sectional moment of inertia; the moment of inertia is inverse to the deflection created by the load on the shelf~ Thus, an increase in the moment of inertia of each of the integral 3~
9D-HR-167'71 stringers o~ the inner panel increases the sti~Pnes~
through decreasing the deflection created by the load on the shelf. The moment of inertia of each o~ the integral stringers can be varied throuyh varyiny its width, its height, or its pattern shape.
Each of the shelves is rigidized against deflection under load by extending each of the integral stringers into a gusset or truss, either beneath or above the shelf. The gusset preferably has the same pattern shape as the integral stringer ~rom which it extends.
The US2 of the integral stringers and the gussets diffuses the stress throughout the inner panel rather than at local areas of the inner panel as occurs with pre~iously used smooth surface designs. This enables a relatively large load to be supported by relatively thin material.
By selecting the shape of the pattern as a V-shape or a U-shape, the aesthetic appearance of the inner panel is enhanced. By using di~ferent pattern shapes with inner panels of dif~erent price model lines, a diferentiation between model lines i~
produced.
SUMMARY OF THE INVENI'ION
An object of thi~ invention is to provide an appliance door having a uni~uely ~tifEened inner panel.
Another object of this invention is to provid~ a sti~fened inner panel of an appliance door having an esthetic appearance.
A ~urther object o~ this invention is to provide ~ 39 gD-HR-16771 an appliance door having an inner panel capable of supporting a much larger load on its shelves with the same thickness of the inner panel.
Still another ob~ect o~ this invention is to provide a method of stif~ening an inner panel of an appliance door while having an aesthetic appearance.
A still further object of this invention is to provide a method of forming an inner panel of an appliance door that is capable o* supporting a much larger load on its shelves with the same thickness of the inner panel.
Other objects of this invention will be readily perceived from the following description, claims, and drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
The attached drawings illustrate pre~erred embodiments of the in~ention, in which:
FIG. 1 is a front elevational view of a refrigerator cabinet with its lower door in an open position and having an inner panel of the lower door stiffened in accordance with the present invention;
FIG. 2 is a longitudinal sectional view o~ the lower door of FIG. 1 having the sti~fened inner panel;
FIG. 3 is a ~ragmentary isometric view, partly :in seckion, o~ a portion of the door of FIG. 2 and showlng stif~enin~ o~ the inner panel through the use of V-shaped stringers with V-shaped gussets far shelves integral with the inner panel;
FIG. 4 is an enlarged fragmentary isometric view, partly in section, of a portion of the door of ~IG. 3 9D~HR~16771 and showing details of the V-shaped gussets for stiffening the shelves;
FIG. 5 is an enlarged ~ragmentary isometric view, partly in section, of a door having U-shaped stringers in its inner panel, its bottom shel~ having U-shaped gussets and a shadow line, and its other shelves having V-shaped gussets;
FIG. 6 is an enlarged fragmentary isometric view, partly in section, showing the lowermost portion of the door of PIG. 1 having its inner panel formed with V-shaped stringers and its bottQm shelf stiffened only by a shadow line;
FIG. 7 is an enlarged fragmentary isometric view, partly in section, showing the lowermost portion of a door having its inner panel formed with V-shaped stringers and its lower shelf having V-shaped gussets on its upper surface;
FI~. 8 is an enlarged fragmentary isometric view, partly in section, showing the lowermost portion of a door having its inner panel formed with U-shaped stringers with its lower shelf having V-shaped gussets on its upper surface;
FIG. 9 is an enlarged fragmentary longitudinal sectional view of a portion of the door of :FIG~ 1 and showing the blending o~ a V-shaped str:Lnyer on the inner panel with a V-3haped gusset on a lower surface o~ a shelf; and FIG. 10 is an enlarged fraymentary longitudinal sectional view of a portion of the door of FIG. 5 and showing the blending of a U-shaped integral stringer with a U-shaped gusset on a bottom surface of the lower shelf and the blending of the U-shaped 3~3~

stringer with a V-shaped gusset on the bottom surf~c~
of an intermediate shel~.
DESCRIPTIO~ OF THE PREFERRED EMBODIMENTS
Referring to the drawings and particularly FIG.
1, there is shown a refrigerator cabinet- 10 having an upper door 11 and a lower door 12. The upper door 11 closes an access opening (not shown) in a front wall 14 of the refrigerator cabinet 10 to a freezer compartment (not shown). The lower wall 12 closes an access openiny 15 in the front wall 14 to a fresh food compartment 16.
As shown in FIG. 2, the lower door 12 includes a metallic outer panel 17 and an inner panel 18 of a plastic such as ABS, for example, connected to each other with an insulating foam 19 therebetween. The outer panel 17 has a flange 20 at its rear extending around its entire periphery and with which a peripheral mounting flange 20' o~ the inner panel 18 is attached by suitable means such as screws extending through holes and notches in the mounting flange 20' into screw start holes in khe flange 20, for example.
The inner panel 18 has a bo~tom shel~ 21~ ~wo intermediate shelves 22 and 23, and a top shel~ 24 formed int~gral kherewith. ~here also is an upper portion or wall 25 adjacent the upper end o~ the inner panel 1~ and ~ormed inkegral therewith. The upper portion 25 prevents escape of re~rigerated air from the fresh ~ood compartment 16 ~see FIG. 1) and turns of~ a light (not shown) therein when the door 12 is in its closed position.

3~

The inner panel 18 ~see FIG. 2~ has a side wall or connector 26 extending from each end of the upper portion 25 to each end of the bottom shelf 21. The side walls or connectors 26 carry part of the load on the substantially horizontal shelves 21-24 as they are secured to opposite ends of each.
The inner panel 18 includes a substantially vertical surface 27 extending between an upper surface 28 of the lower shelf 21 and a lower surface 29 of the inkermediate shelf 22, a substantially vertical surface 30 extending between an upper surface 31 of the intermediate shelf 22 and a lower surface 32 of the intermediate shelf 23, and a substantially vertical surface 33 extending between an upper surface 34 of the intermediate shelf 23 and a lower surface 35 of the upper shelf 24. Each of the surfaces 27, 30, and 33 of the inner panel 1~ is similarly formed.
As shown in FIGS. 3 and 4, the sur~ace 30, ~or example, has a plurality of integral stringers 40 formed therein adjacent ~o each other in a V-shape.
Each of the stringers 40 extends ~rom the upper surfaae 31 of the intermediate shelf 22 to the lower surface 32 o~ the intermediate shelf 23. The integral stringers 40 termlnate prior to each o~ the side walls or connectors 26. The sur~aces ~7 an~ 33 of the inner panel 1~ are similarly Pormed with the integral stringers 40.
Each of the integral stringers 40 is identical with each of its sides 41 and 4~ being identical.
Since an increass in the moment of inertia of each of the integral stringers 40 increases 9 D--:H~ 1 6 r7 7 1 the stiffness of the surface 30, for example, of the inner panel 10 so as to decrease the ~hickness of the inner panel 18 to support a specific load, it is desired to have the moment o~ inertia an optimum 5 consistent with an aesthetic appearance of khe surfaces 27 (see FI~. 2), 30, and 33 of the inner panel 18. Because a plastic such as ABS, for example, will crack when subjected to too high a strain, the moment of inertia is selected so that such will not occur while still increasing the stiffness.
For a specific thickness of the inner panel 18, the moment of inertia can be increased by increasing the angle of the sides 41 (see FIG. 3) and 42 of the stringer 40 to each other. The moment of inertia also can be increasPd by increasing the distance between the spaced ends o~ the sides 41 and 42. As shown in FIG. 6, only the spaced ends of the sides 41 and 42 of each o~ the integral stringers 40 engage the insulating foam 19.
As shown in FIGS. 4 and 9, each of the integral stringers 40 in ~he sur~ace 30 blends into a gusset or truss 43 in the lower surface 32 o~ the intermediate shelf 23. As shown in FIG. 4l the integral strinyer~ 40 in the surfaceF, 27 and 33 similarly blend into the gussets or trusses ~3 :I.n th~
lower surface 29 o~ the intermediate shelf 22 and the lower sur~ace 35 o~ the upper shelf 24, respectively.
The gu~set or truss 43 has the same con~iguration as the integral stringer 40 so that it has two sides 44 and 45. Because of the height of the shelf 23, the sides 44 and 45 are at a ~ 3~ 9D-H~_~771 di~ferent angle to each other than the sides 41 and 4~ of the integral stringer 40.
The moment of inertia of each of the gussets or trusses 43 strengthens the intermediate shel~ 23 so that it does not deflect to the same extent as it would if it did not have the gussets or trusses 43.
This decreases the required thickness of the inner panel 18 while still maintaining the load supporting capability.
Because of the locakion of the bottom shelf 21 (see FIG. 2) so close to the bottom of the door 12, it is not possible to form any of the integral stringers 40 ~see FIG. 3) therebeneath or thP gussets or trusses 43 in lower surface 46 (see FIG. 2) of the ~5 bottom shelf 21. Instead, the bottom shelf 21 has a shadow line 47, which is a groove, formed in its portion ~oining the upper surface 28 and the lower surface 46 of the bottom shel~ 21. The shadow line 47 provides enhancement of the moment of inertia in addition to providin~ an aesth~tic appearance. The increased moment o~ inertia is due to the moment of inertia o~ a flat plate heing proportional to its thickness and heighk and the shadow line 47 increases the equivalent thickness.
The integral ætringers 40 (see FIG. 3) extend ~or approximat~ly 90 to 95 per cent of the width o~ each of the sur~aces 27, 30, and 33 o:~ the inner panel ~.
The guæ~ets 43 extend for the same distance a~ the integral skringers 40.

~ ~ 9D-HR~16771 Because of a large ball radius 48 (see FIG 4) at the junction of the top surface 31 of the shelf 22 and the side wall or connector 26, for example, the integral stringers 40 cannot extend ~or the entire width of the surfaces 27, 30, and 33. This is because of the material thinness o~ the ball radius 48 and the ball radius 48 preventing a load concentration at its location. While the ball radius 48 is shown only at the top surface ~f the various shelves, it should be understood that a ball radius, which is usually much smaller than the ball radius 48, may be employed at the bottom surface of the various shelves if desired.
Accordingly, as shown in FIGS. 3 and 4, for example, a decorative stringer 49 may be employed at each end of the integral stringers 40. Since the decorative stringer 49 is not intended as a load carrying stringer, one o~ the gussets 43 is not disposed above the decorative stringer 49.
It should be understood that only one of the decorative stringers 49 is used at each end o~ the integra} stringers 40 in each of the surfaces 27, 30, and 33. If the spacing of the last of the integral stringers 40 from the side wall or connector 26 woulcl be such that it would require two of the decorat.lve ~tringers 49 at each snd of the integral stringers 40, then the spaced end~ o~ the sides 41 and 42 of each o~ the integral stringers 40 would be moved further apart so as to require only one of th~
decorative stringers 49 at each end of the integral stringers 40.

~4~3~3 9D-~IR-l6771 Referring to FIG. 5, there is shown a lower door 50 for use with the refrigerator cabinet 10 (see FI~.
1) instead o~ the lower door 12. The lower door 50 (see FIG. 5) includes a metallic outer panel 51 and a plastic inner panel 52 joined in the same manner as the outer panel 17 (see FIG. 2) and the inner panel 18. An insulating foam 53 (see FIG. 5) is disposed between the outer panel 51 and the inner panel 52 of the lower door 50.
The inner panel 5~ has a bottom shelf 54 with a plurality of additional substantially horizontal shelves (one shown at 55) thereabove. The bottom shelf 54 is spaced substantially from the bottom of the door 50.
The inner panel 52 has each of its substantially vertical sur~aces 56, 57, and 58 formed with identical integral stringers 59. Each of the integral stringers 59 has a substantially U~shaped configuration having a base 60 and a pair of legs 61 and 62 extending at an angle greater than 9Q from the base 60. The moment of inertia of each of the U-shaped integral stringers 59 is increased with an increase in the thickness o~ the base 60 (This is an increase in the thickness of the inner panel 52.), an increase ln the distance between the lnner sur~aces of the legs 61 and 62 of the U-shaped strinyer 59, or an increa~e in the length o~ each o~ the leg~ 61 ancl 62 of the U-shaped integral stringer 59.
As shown in FIGS. 5 and 10, the integral stringers 59 blend into U-shaped gussets or trusses 63 in a lower surface 64 of the bottom shelf 54 having substantially the same U~shape as ths 1~

integral stringers 59 and into the V-shaped gussets or trusses 43 in a lower surface 65 of the shel~ 55 and a lower surface of each of the other shelves integral with the inner panel 52. As shown in FIG.
5, each of the gussets 63 has a base 66 of the sa~e length between its legs 67 and 68 as the base 60 of the integral stringer 59, but the legs 67 and 68 are of varying length.
The bottom shelf 54 also has a shadow line 69, which is a groove, formed in its portion ~oining the bottom surface 64 and its upper surface 70. This enhances the moment of inertia while providing an aesthetic appearance.
The integral stringers 59 extend for approximately 90 to 95 per cent of the surfaces 57 and 58 of the inner panel 52 and for the entirs width of the surface 56 of the inner panel 52~ The integral stringers 59 can extend for the enkire width of the surface 56 because there is no large ball radius beneath the lower surface 64 of the bottom shelf 54.
There is no decorative stringer in the surfaces 57 and 58 of the inner panel 52 although there could be if desired. Such decorative stringers wou:Ld be of the same shape as the integral stringers 59.
Referring to FI~. 7, there is shown a portion of a lower door 71 ~or use with the refrigerator cabinet 10 (see FIG. 1) instead of the lower door 12. The lower door 71 ~see FIG. 7) has a bottom shelf 72 formed integral with its inner panel 73. The inner panel 73 has its substantially vertical surface 74 extending 9D~HR-16771 upwardly from an upper surface 75 of the bottom shelf 71 to another shelf (not shown).
The surface 74 is formed with the integral stringers 40 of the same V-shaped configuration as shown in FIG. 3 for the lower door 12. However, there is no decorative stringer as the decorative stringer 4~, for example, at each end of the integral stringers 40 in FIG. 7 although there could be if desired.
Each of the integral stringers 40 of the V-shaped configuration blends into a gusset or truss 76 of the same V-shape in the upper surface 75 of the bottom shelf 72. Thus, the gussets or trusses 76 provide rigidity to the bottom shelf 71. There is sufficient support surPace on the gussets or trusses 76 for containers to be placed thereon without signi~icant tilting.
Referring to FIG~ ~, there is shown a lower door 80 for use with the refrigerator cabinet 10 (see FIG.
1) instead of the lower door 12. The lower door 80 (see FIG. 8) has its bottom shelf 81 formed inteyral with its inner panel 82 and other substantiall~
horizontal shelves khereabove formed integral with the inner panel 82. The inner panel 82 ha~ its substantially vertical sur~ace 83 and its other ~imilar ~ubstantially vertical sur~aces ~ormed with the integral etrinyer~ 59 o:E U-shaped con~iguration as in ~IG~ 5. There i~ no decorative stringer at each end o~ the integral stringers 59, which extend for approximately 90 to 95 per cent oP the width of the surface 83, although there could be if desired.
Such decorative stringers would be of the same 12~ 9 shape as the integral stringers 59.
The bottom shelf 81 (see FIG. 8) has yusseks or trusses 84 in its upper surface 85 ~ormed of the V-shaped configuration in the same manner as the gussets or trussas 76 (see FIG. 7) o~ the lower door 71. Thus, the door 80 (see FIG. 8~ has the integral stringers ~9 of a different configuration than the gussets or trusses 84. However, they blend together to provide the desired rigidity to the inner panel 82 and the bottom shelf 81. The other shelves of th~
inner panel 82 would have the gussets or trusses 84 of the same configuration as the bottom shelf 81.
Accordingly, the gussets or trusses ~ay be formed at either an upper or lower surface or both surfaces of a shelf of the inner panel of a refrigerator door for strengthening the shelves so that they will not deflect as much for a specific thickness of the inner panel. Furthermore, integral stringers may be utilized between the shelves to provide the desired skiffness to the inner panel whereby it does not have to be as thick to support increased loads.
It should be understood that the upper door 11 (see FIG. 1) may be similarly formed ag the lower door 12. The present invention also may be employed with a re~rigerator hav:Lng a single door.
While the present invention has been shown and described ~or a refrigerator, it should be understood that any other appliance having a door with shelves on which containers or the like are to be supported may be so formed~ Thus, the present invention may be used with any appliance door requiring stiffness and support of shelves integrally formed with the inner panel of the appliance door.
While the present invention has shown the integral stringers being formed of eith~r a V-shaped, which is an open triangle, or a U-shape, it should be understood that any other shape may be employed that will produce an aesthetic appearance in the inner panel in which it is formed while still obtaininy the optimum moment of inertia to obtain a desired sti~fness with an aesthetic appearance. Furthermore, while the integral stringers 59 (see FlG. 5) may be utilized with the V-shaped gussets or trusses 43 or 84 ~see FIG. 8) or with the U-shaped gussets vr trussPs 63 (see FIG. 5), the V-shaped integral stringers 40 (see FIG. 4) can be employed only with the V-shaped gussets or trusses 43.
An advantage of this invention is that a substantial reduction in the amount of material required for an inner panel of an appliance door to support a specific load is obtained so as to substantially decrease the C05t 0~ the material.
Another advantage o~ this invention is that an inner panel of an appliance door is stiffened without adding any makerial. A further advantage of this invention is that stress is diEfused throughout the entire area o~ an inner panel of an appliance door rather than at limited local areas. Still another advantage of this invention is that the aesthetic appearance of an inner panel of an appliance door is maintained while increasing its stiffness.

3~

For purposes of exemplification, particular embodiments of the invention have been shown and described according to the best present understanding thereof. However, it will be apparent that chanyes and modifications in the arrangement and construction of the parts thereof may be resorted to without departing from the spirit and scope of the invention.

Claims (20)

1. An appliance door including:
an outer panel;
an inner panel connected to said outer panel;
and said inner panel including:
a plurality of substantially horizontal shelves having an upper surface and a lower surface spaced from each other;
a substantially vertical surface extending between at least each two adjacent of said shelves;
a plurality of integral stringers of the same configuration adjacent each other and extending between at least two adjacent of said shelves in said substantially vertical surface extending therebetween;
and gusset means extending from one end of each of said integral stringers, said gusset means being in one of said upper and lower surfaces of at least one of said two adjacent shelves to add rigidity to said one shelf, each of said gusset means having the same configuration.

2. The door according to claim 1 in which each of said gusset means is in said upper surface of said shelf.

3. The door according to claim 2 in which each of said gusset means is the same configuration as each of said integral stringers.

4. The door according to claim 3 in which each of said integral stringers has a substantially V-shaped configuration.

5. The door according to claim 3 in which each of said integral stringers has a substantially U-shaped configuration.

6. The door according to claim 2 in which each of said integral stringers has a substantially U-shaped configuration and each of said gusset means has a substantially V-shaped configuration.

7. The door according to claim 1 in which each of said gusset means is in said lower surface of said shelf.

8. The door according to claim 7 in which each of said gusset means is the same configuration as each of said integral stringers.

9. The door according to claim 8 in which each of said integral stringers has a substantially V-shaped configuration.

10. The door according to claim 8 in which each of said integral stringers has a substantially U-shaped configuration.

11. The door according to claim 7 in which each of said integral stringers has a substantially U-shaped configuration and each of said gusset means has a substantially V-shaped configuration.

12. The door according to claim 1 in which each of said gusset means is the same configuration as each of said integral stringers.

13. The door according to claim 12 in which each of said integral stringers has a substantially V-shaped configuration.

14. The door according to claim 12 in which each of said integral stringers has a substantially U-shaped configuration.

15. The door according to claim 1 in which each of said integral stringers has a substantially U-shaped configuration and each of said gusset means has a substantially V-shaped configuration.

16. A method of forming an inner panel of an appliance door including:
forming a plurality of substantially horizontal shelves integral with the inner panel;
forming a plurality of integral stringers of the same configuration adjacent each other in a surface of the inner panel extending between at least two adjacent of the shelves for substantially the entire width of the shelves to increase the stiffness of the surface of the inner panel;
and forming gusset means of the same configuration in one of the upper and lower surfaces of at least one of the two adjacent shelves with each of the gusset means extending from one end of each of the integral stringers to add rigidity to the shelf having the gusset means.

17. The method according to claim 16 including forming the integral stringers and the gusset means of the same configuration.

18. The method according to claim 17 including forming each of the integral stringers and the gusset means in a substantially V-shaped configuration.

19. The method according to claim 17 including forming each of the integral stringers and the gusset means in a substantially U-shaped configuration.

20. The method according to claim 16 including:
forming each of the integral stringers in a substantially U-shaped configuration;
and forming each of the gusset means in a substantially V-shaped configuration.