Note: Descriptions are shown in the official language in which they were submitted.
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9D--HR-16771
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
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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
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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
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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
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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
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9D-HR-16771
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.
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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
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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
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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.
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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.
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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
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9D-HR--16771
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
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9D-HR-16771
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
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9D-HR-16771
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.
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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.
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