Note: Descriptions are shown in the official language in which they were submitted.
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MODULAR CUSHION CONSTRUCTION WITH FOAMED BASE
This is a divisional application of copending
application 2,108,685 filed December 7, 1992.
BACKGROUND OF THE INVENTION
This. invention relates in general to cushions
for seating and more particularly to a modular
wheelchair cushion which has a shaped foam base, a
fluid filled or foam cellular pad covering part of
the base, and a fabric cover enclosing the base and
the pad.
Those who must spend extended time in
wheelchairs run the risk of tissue breakdown and the
development of pressure sores, which are extremely
dangerous and difficult to cure. These pressure
sores are decubitus ulcers, typically formed in areas
where bony prominences exist, such as the ischia,
heels, elbows, ears and shoulders. Typically, when
sitting much of the individual's weight concentrates
in the regions of the ischia, that is at the bony
prominences of the buttocks and unless frequent
movement occurs, the flow of blood to the skin tissue
in these regions decreases to the point that the
tissue breaks down. This problem is well known and
many forms of cushions are especially designed for
wheelchairs for reducing the concentration of weight
in the region of the ischia, and these cushions
generally seek to distribute the user's weight more
uniformly over a larger area of the buttocks.
Another area where problems occur is in the
trochanter area and both cushions and bases for the
cushions are shaped so that the thighs are hoaded and
pressure is relieved on the ischia and the
trochanters. Still another problem with wheelchair
type cushions is stabilization of the user so that he
has a feeling of security when sitting in the
wheelchair.
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A number of patents show cellular cushions which comprise
an array of closely spaced air cells which project upwardly
from a common base and are interconnected. These cushions
combine the most uniform distribution of weight and thus
provide the greatest protection from the occurrence of
pressure sores. Since the air cells communicate with each
other, all exist at the same internal pressure and each air
cell exerts essentially the same restoring force against the
buttocks, irrespective of the extent to which it is deflected.
U.S. Patent No. 4,541,136 shows a cellular cushion currently
manufactured and sold by Roho, Inc. of Belleville, Illinois
for use on wheelchairs.
The stability problem has been attacked by the use of
shaped bases such as shown in Graebe U.S. Patent No. 4,953,913
and Jay U.S. Patent No. 4,726,624. These bases are generally
used in conjunction with cushions and Graebe U.S. Patent No.
4,953,913 has been used in conjunction with a cellular cushion
and a fabric cover. The stability problem also has been
addressed in the cellular cushion field by the use of zoned
areas of inflation as shown in Graebe U.S. Patent No.
4,698,864 which shows a zoned cellular cushion with cells of
varying height and Graebe U.S. Patent No. 5,052,068 which
shows another form of zoned cushions with cells of different
heights.
Graebe U.S. Patent No. 5,111,544 shows a cover for a
zoned cellular cushion which keeps the cells from deflecting
outwardly. This cover has a stretchable top, a skid resistant
base and a non-stretchable fabric side panel area.
The present invention resides in a foamed base having a
flat rear area onto which may be fastened a
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variety of pads, including those which have a shaped
surface to conform to body shapes, preferably a pad
formed with upstanding air inflated cells. The base
has a raised shaped front designed to load the thighs
and separate the legs to stabilize the pelvis. A
fabric cover forms the outside of the composite
cushion and has a portion of the top formed of
stretchable material and the remainder of the top and
sides formed of a slick non-stretchable fabric with a
skid resistant base. The base by itself is useful by
able bodied persons who have good tissue bulk around
their legs, whereas disabled persons who do not have
good thigh bulk benefit by having a fluid filled
module, such as an inflated air module, or a suitable
foam module installed on the rear area.
The invention also consists in the parts and in
the arrangements and combinations of parts
hereinafter described and claimed.
DESCRIPTION OF THE DRAWINGS
In the accompanying drawings which form part of
the specification and wherein like numerals and
letters refer to like parts wherever~they occur:
Fig. 1 is a perspective view of the modular
cushion of this invention;
Fig. 2 is a perspective view similar to Fig. 1
with the cover removed and showing only the base and
a cellular cushion;
Fig. 3 is a sectional view taken along line 3 -
3 of Fig. 1;
Fig. 4 is a fragmentary plan view with part of
the cover broken away;
Fig. 5 is a fragmentary sectional view taken
along line 5 - 5 of Fig. 4;
Fig. 6 is a perspective view of the cellular
cushion;
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Fig. 7 is a fragmentary plan view of a portion
of the base of the cover.
Fig. 8 is a fragmentary plan view of another
modified cushion;
Fig. 9 is a fragmentary sectional view taken
along line 9 - 9 of Fig. 8;
Fig. 10 is a fragmentary plan view of another
modified cushion;
Fig. 11 is an end elevational view of the
modification shown in Fig. 10;
Fig. 11A is a rear view of a modification of the
cushion shown in Fig. 10;
Fig. 12 is a bottom perpective view of a
modified base;
Fig. 13 is a bottom perspective view of a
cushion designed to be used with the base shown in
Fig. 12;
Fig. 14 is a sectional view taken along line 14
- 14 of Fig. 12;
Fig. 15 is a fragmentary sectional view taken
along line 15 - 15 of Fig. 14.
Fig. 16 is a top plan view showing storage of an
inflation hose;
Fig. 17 is a sectional view taken along line 17
- 17 of Fig. 16 showing storage of an inflation hose;
Fig. 18 is a perspective view of a leg
positioner module; and
Fig. 19 is a partial sectional view taken along
line 19 - 19 of Fig. 18.
DETAILED DESCRIPTION
Figs. 1 and 2 show the preferred form of the
composite modular cushion 10 which comprises an outer
cover 11 and, as shown in Fig. 2, a shaped base 12
and an inflatable cellular cushion 13 formed with
upstanding air cells 14.
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The base 12 is shown in more detail in Figs. 2,
3 and 4 and comprises a flat rear area 20 and a
raised front area 21. A sloped or inclined
connecting,area 22 connects the rear area 20 with the
front area 21. The sloped connecting area 22 is
shown more clearly in Fig. 3. This step down offset
is designed to force support to the thighs and
relieve pressure to the ischial and the trochanters.
The base also includes a tapered front face 23 as
seen in Figs: 3 and 4 and inwardly curved thigh
loading areas 24 at the side edges of the front 21.
These areas are sloped inwardly from the outer side
edges to provide the proper thigh loading
characteristics without providing too much pressure
against the thighs. In the center of the front area
21 is a raised pommel 25 which is higher than the
side areas 24 and is designed to separate the legs,
stabilize the pelvis, and to help keep the user from
sliding out of his seat. Between the raised side
areas 24 and the pommel 25 are dish shaped leg
retaining valleys 26 which are angularly inclined
outwardly away from the rear base area 20 along the
lines X X in Fig. 4 so as to separate the legs in
conjunction with the pommel 25.
The base 12 is formed of foamed plastic of
polyurethane type and may have various indent
densities based on the needs of the user. During
molding a skin is formed which is resistant to
moisture and chemicals and can be washed and
sterilized, if necessary, using conventional
techniques.
The underside of the pommel 25 can be hollowed
out at 75 to give a softer feel to the center section
25. This is shown in Figs. 3 and 4. If this feel is
not necessary, the hollowed out section 75 may be
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molded solid with the rest of the base 12. Recesses
27 are molded in selected locations, such as the
center of the underside of the flat rear base area
20, and are designed to accommodate the male portion
28 of a snap fastener. 'the snap fastener is exposed
to the top surface of the rear base area 20 so that
the air cell module 13 can be attached thereto a:a
will be hereinafter described. Other suitable
fastening means such as Velcro strips can be used
where needed, if desired.
An alternative construction is shown in Figs.
12,14 & 15 in which slots 70 are molded into the
underside of the front of the base 12a. The slogs 70
are parallel to and spaced inwardly from the base'
side edges and terminate in access openings 71 which
open into the top surface of the base 12a adjacent to
the connecting area 22. The slots 70 terminate ;short
of the base front 23 and also have openings at 72 to
the front 23 of the basa_ 12. The solid webs 73 help
stabilize the base front 23. The slots 70
accommodate tubes 33a connected to an air cell of the air
inflatable pad 13 so that the air valves 34a for the pad 13
are accessible from the front of the cushion 10 whereby they
can be inflated and adjusted readily by the user while he is
sitting on the modular cushion 10. This can be used with any
number of sets of air cells and can be used with the pad of
Fig. 2 or the pad of Fig. 8.
The alternative construction also lends itself
to the concept of_ communicating with the undersurface
of a module through the base. Using the concept,
individual cells can be monitored and a profile of
the weight distribution of the user can be
determined. This involves a pressure measuring
system beyond the scope of this disclosure but the
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communication with the underside of a cushion through
the base makes this possible. The slots 70 may be
located to exit at any edge and in any number as rnay
be required.
The inflatable cushion or module 13 has a
flexible base 30 of substantially rectangular shape
and the air cells 14 project upwardly from the base
30. In the preferred embodiment shown in detail :in
Figs. 2 - 6, there are two zones A and B which are
distinct and separated by a center area 31. The air
cells 14 in each of the zones A and B are
interconnected b:y means of passages 32. Thus, the
air pressure in the cells 14 in each zone is the name
but the air pressure in the zones A and B can be
different based on the configuration of the patient.
Each of the zones r4as a separate fill tube 33 connected to an
air cell which has a closure valve 34 on the end thereof. If
t:he fill tube 33 with the closure valve 34 is not used, each
of the zones A and B is provided with a test opening
connected to one of the air cells 14. This is designed to be
closed with a plug which is removable for factory testing and
air pressure p.reshioment adjustment.
These passages.32 may be constructed as
described in Graebe U.S. Patent No. 4,541,136 or may
be raised tunnels molded into the top member where
the air cells 14 are formed. The tunnels may have a
high aspect ratio to exclude glue from the tunnels
when the top and base are glued together.
This arrangement is shown and hereinafter
described in conjunction with the modification of the
invention shown in Figs. 8 and 9, but also can be
used with the pad shown in Figs. 1 - 6 or any other
variation of the air inflated cellular module.
Positioned through the module base 30 in
_ alignment with the shaped base recesses 27 are the
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female portions 37 of a snap fastener arrangment.
This is shown in Fig. 5 and allows the module 13 to
be snapped and fastened to the base 12.
As previously noted the module 13 can be formed
from preinflated cells 14 rather than using the fill
tube 33. If the fill tube 33 is eliminated, the
modules 13 are prefilled at the factory with a
predetermined air pressure and this pressure cannot
be adjusted by the user. The cells 14 are still
interconnected within each zone A and B but the
pressure in the zones A and B cannot be adjusted
after once being established..
The air cells 14 are of pyramidal shape and have
a square bottom, rectangular side edges 38, tapered
top side 39 of trapezodial shape, and a substantially
flat top 40. The purpose of the pyramid shape is to
provide a means to collapse the air cell in a
controlled manner during the engagement phase by the
person sitting on the points formed by the pyramid.
The higher the point the greater the engagement
travel which gradually builds up the internal
pressure of the cell giving a low force entry zone.
This entry zone is especially useful when prefilled
or sealed air cells are used. The air cells 14 are
spaced from each other by lateral and longitudinal
passages 15 and stand independently of each other
when~erected and filled with air. The inflatable
module 13 is formed of a flexible material such as
neoprene rubber, or the like.
Other types of snap fastened cushions or pads
can be used and several of these are shown in Figs. 8
and 10. The module 41 of Figs. 8 - 9 has two
separate inflatable cells 41a,41b separated by a seam
42 and filled through air valves 43a,43b. As
hereinbefore noted, this form of the invention is
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shown as having the air chambers 41a, 41b prefilled at the
factory with a predetermined air pressure and the fill tubes
43a, 43b are sealed with plugs 44a, 44b which are similar to
pencil erasers. Thus, the air pressure in the chamber 41a, 41b
cannot be adjusted by the user. As mentioned, this type :pad
can use the inflation systems shown in Figs. 1 - 6 or
Figs. 12 - 15. Individual sealed cells also can be used in the
pad.
A modification of the pad 41 is shown in Figs. 12 - 1~
This modification is usad with the base shown in Fig. 12 ar
the pad 41 is adjustable from the front. The pad 41 is
provided with fill tubes 33a connected to an air cell and
which extend from the underside of the pad 41 and are
positioned in the base sl.c=s 70 so that the fill nozzles 34a
are accessible from the front to more readily be adjustable
by the user. This construction also can be used with the
inflatable pad 13 shown in Fig. 1-6. a
molded foamed plastic and, as shown, has hollow dome shaped
members 66 similar to those shown in Sias et al U.S. Patent
Nos. 4,673,505, 4,605,5F~2 and U.S. Design Patent No. 294,212.
The foamed pad 65 can be "T - Foam", molded domes 66, or arch
elements as shown i.n Graebe U.S. Patent No. 4,713,854, anal can
be made to better fit the patier..t by shaping the surface of
the foam or adjusting true size or resiliency of the
projections. A modificat.i.on of the cushion 65a is shown in
Fig. 11A which shows a shaped cushion surface in which the
domes 66a are of different heights.
The base 12 can be used alone or in combination with any
one of the cushions 13, 41, 65 or 65a. The base and cushion
also can be used in combination with the cover 11.
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The cover 11 contains some features in common with Graebe
U.S. Patent No. 5,111,544 and as shown in Figs. 1, 3, 4 and 7,
includes a top panel 45, a bottom panel 46, side panels 47, a
front panel 48 and a rear panel 49. The front, bottom, side,
rear and bottom panels are stitched together along their edges
to define the cover 11. The respective panels generally
conform to the shape of the portions of the shaped base 12
over which they fit. The rear panel 49 is severed into two
sections 50, 51 which are connected by suitable fastening
means, such as a zipper 52, which also can extend into the
side panels 47 as far as is necessary to obtain access to the
fill valve 33. for example, the zipper 52 can extend
completely to a valve stem stored in the sloped wall 22 of the
base 12 as described hereinafter in Figs. 16 and 17. This
allows the cover 11 to be slipped over the base 12 and the
attached inflatable module 13. It also allows the cover 11 to
be removed for cleaning, etc. The rearward ends of the top
panel 45 are shortened at the corners to define openings 52,
53 through which the fill tubes 33 and valves 34 extend to
allow the module 13 to be filled without removing the cover
li. If the fill tube is positioned in the slots 70, the
openings 52, 53 are at the front edges of the cover 11 to
provide access to the fill tubes 33. The top cover 45 is
formed of two sections of dissimilar material. The rear
section 55 is formed from a highly elastic fabric, i.e., one
that stretches in any direction. The elasticity of the top
panel 55 enables that panel to conform to the shape of the
user's buttocks when the user sits on the inflatable module 13
and minimizes the "membrane effect" of the cover. The top
panel section 55 simply follows the
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contour of the seating surface created by the upper
ends 40 of the air cells 14. It detracts little from
the capacity of the array of air cells 14 to conform
to the shape of the user's buttocks. The forward
portion 56 of the top panel 45, the side panels 47,
the front panel 48, and the rear panel 49 are formed
from a traditional fabric, i.e., one that offers low
friction with flexibility, yet is very durable.
Typical nylon fabric is suited for this purpose. The
forward portion 56 of the top panel 45 offers low
friction to aid the user in performing slide
transfers on and off the cushion. These sections can
be formed from one or more parts and stitched
together and stitched to the other panels.
The bottom panel 46 is formed from a high
friction mesh 60 (Fig. 7) known as vinyl coated
skrim. The mesh 60 consists of polyester fibers
woven into an open weave and a polyvinyl chloride
coating covering the polyester vinyl fibers without
obliterating the openings of the weave. The
polyvinyl chloride coating allows the cushion cover
11 to be cleaned and sterilized without causing the
fabric coating to become slick and slippery. In
other words, it retains its anti-skid or high
friction characteristics. The weave of the bottom
panel 46 is such that the mesh 60 has relatively
thick ribs 61 extending parallel between opposite
edges of the panel 46 and thinner connecting segments
62 extending between the ribs 61 and oriented at
right angles with respect to the ribs 61, with the
spacing between the connecting segments 62 being
about the same as the spacing between the ribs 61.
This forms a series of square openings which are
divided by diagonal segments 63 that extend between
the connecting segments 62 and cross at the centers
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of the square openings. The coating is a high
co-efficient of friction against traditional seating
surfaces such as wood, metal or fabric, and the
friction that develops is particularly affective
along the thick ribs 61. The co-efficient of
friction between the coating and such surfaces is
substantially greater than the co-efficient of
friction between the top or side panels 45, 47, 48
and 49 and such surfaces. The mesh 60 is commonly
used as an underlayment for throw rugs to prevent
them from slipping on traditional flooring materials
such as tile, vinyl and hardwood. It may be obtained
from Vantage Industries, Inc. of Atlanta, Georgia.
The high friction mesh 61 of the bottom panel 46
prevents the cover 11, base 12 and module 13
overwhich it fits from sliding over a supporting
surface such as the seat of a wheelchair or the seat
of a traditional chair or bench. In addition, it
admits air to the.interior of the cover 11 where the
air can circulate through the array of air cells 14.
Finally, it permits moisture to drain from the
interior of the cover 11.
In use, the cover 11 containing the shaped base
12 and with or without the inflatable module 13 is
placed on a supporting surface such as the seat of a
wheel chair or a seat of a traditional chair or bench
with the bottom panel 46 presented downwardly against
the supporting surface. The user's weight is
distributed generally uniformly over the portion of
the cushion 10 which is defined by the rear section
50 of the top panel 46, i.e., that portion supported
by the inflatable module 13. The portion of the
user's weight which is supported by that portion of
the base 12 which is covered by the front section 56
of the top panel 45 is directed by the shape of the
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base 12 to the thighs and to relieve pressure on the
ischial and the trochanters. The directed contours
26 and the pommel 25 separate the legs and in
combination with the new slip cover helps to prevent
a user from sliding out of position and the chair
seat.
The high co-efficient of friction that exists
between the bottom panel 46 and the underlying
supporting surface, coupled with the concentration of
the user's weight on that panel 46, stabilizes the
cover ll and the encased base 12 and module 13 that
is difficult to displace. Indeed, it is practically
impossible to slid the combination cover 11, base 12
and module 13 over a traditional wood seating surface
without lifting the combination slightly. T'he bottom
panel 46 is rendered particularly effective by reason
of the mesh 60 and the thicker ribs 61 within that
mesh 60, for it is along the ribs 61 that most of the
friction develops with a supporting surface.
Fig. 16 shows an alternative construction for
the base 12 in which the inflation valve and hose 33
is positioned on the front of the pad 13 and is
retained in an opening 80 formed in the base 12 and
opening at the inclined connecting surface 22. The
inflation valve 34 and hose 33 are stored in the
opening 80 when not in use. Other type projections
on the pad or module 13 can also be inserted into the
openings 80 and, if the fit is sufficiently tight,
can be used as a means for holding the module l3 in
position in lieu of, or in combination with snaps or
Velcro or other fastener.
Figs. 18 and 19 show another modification of the
invention which is a U-shaped retainer 90 positioned
on the cushion 10 over the cover 11. The leg
positioner and restraint 90 has a base 91 and two
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upstanding uprights 92 which project upwardly from
the front of the base 12. Hand grips 93 can be
provided in the free ends of the uprights 92. The
base has stiffeners 94 stamped in it to give it
rigidity. The leg positioner 90 can be covered with
a rubber or vinyl coating, which, in combination with
the vinyl coated skrim on the cover 11 will hold the
positioner 90 in place. If the positioner 90 is used
without a cover 11, Velcro or other fastening tape
can be used. The uprights 92 flare outwardly
slightly and have padding 95 at the top inner surface
to help protect the legs of the user.
The structure 90, when placed under the cushion
l0, serves as a supplemental leg positioner and
restraint to hold the legs of the person toward the
center of the cushion 10. The vertical sides 92 are
long enough to project beyond the leg to not cause
indentation into the flesh. A slight outward flare
can be provided on the top portion of the vertical
uprights 92 to assure easy and safe entering onto the
cushion 10. The hand grip opening 93 can also be
provided in each upright 92 to aid in lifting the
person or provide a push off purchase to aid in
independent transfer off onto the cushion 10.
The leg positioner and restraint 90 is
constructed of molded plastic or 1/16" to 1/8" thick
aluminum, such as 6061 - T6 alloy and can have
V-shaped groves 94 along its length to improve its
stiffness. The preferred construction will have a
vinyl or rubber coating over the metal. Supplemental
padding 95 of foam or air filled cushion can be
attached by Velcro or snaps to the inside of the
position sides 92 to further protect the soft tissue
of the body.
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This invention is intended to cover all changes
and modifications of the example of the invention
herein chosen for purposes of the disclosure which do
not constitute departures from the spirit and scope
of the invention.
