Wheel chair abstract
A wheel chair cushion and the like is disclosed which includes
a cushion formed of a deformable resilient material. The cushion
includes a base having a front wall and a rear wall. A plurality
of individual foam springs are carried by the base having support
surfaces which lie in a plane that is inclined to the base surface
of said base as extending from said front wall to said rear wall.
A pressure relief cut-out is formed substantially in its entirety
from a mid-line of said cushion rearwardly so as to be disposed
underneath the buttocks of a person sitting on the cushion to relieve
pressure in that area and provide increased compressibility of the
foam springs in the pressure relief area to disperse pressure and
provide a resilient depression in the cushion to enhance the patient
retention capability of the cushion as used in a wheel chair.
Wheel chair claims
What is claimed is:
1. A foam cushion for a wheel chair seat constructed from a resilient
deformable foam material, said cushion having a support surface
for evenly dispensing supporting pressure generally over the buttocks
of a person's body while disposed in a seated position in said wheel
chair, said cushion comprising:
a base having a generally planar lower surface supported by said
wheel chair;
a plurality of one-piece foam springs for supporting and cushioning
the body of a person;
said foam springs defining a plurality of blocks which are formed
integral at a first end with said base and which form at a second
end a plurality of generally planar support surfaces;
a plurality of longitudinal and lateral channels, the lateral channels
terminating at said base at unequal locations from said lower surface,
said channels separating said foam springs; and
said planar support surfaces of said foam springs lying in a plane
which is inclined to the plane of said lower planar surface of said
base of said cushion for assisting in person retention in said chair;
a pressure relief means formed as a cavity in the bottom surface
to extend from substantially a mid-section between front and back
walls of said cushion rearwardly to a location in the vicinity of
said back wall for relieving pressure against the bony prominence
of the buttocks of the person seated on said cushion.
2. The device of claim 1 wherein the thickness of said cushion
is a minimum in the area of said pressure relief means in which
a portion of said base is void of material.
3. The device of claim 2 wherein the thickness of said cushion
in the area of said pressure relief means is about one-half the
cushion thickness in adjacent areas.
4. The device of claim 1 wherein, the distance between lower ends
of said lateral channels and said planar lower surface varies between
the front and back walls of said cushion in accordance with the
tapered thickness of said cushion.
5. The device of claim 1 wherein said longitudinal channels have
lower ends which are inclined to said planar lower surface and are
parallel to said plane of said support surfaces.
6. A foam cushion for a chair seat constructed from a resilient
deformable foam material, said cushion having a support surface
for evenly dispensing supporting pressure generally over a person's
entire body while disposed in a seated position in said wheel chair,
said cushion comprising:
a rectangular foam base;
a plurality of individual foam springs carried by said rectangular
base having support surfaces;
said support surfaces of said foam springs lying in a plane, spaced
from to said planar base; and
a pressure relief means formed as a cavity in a bottom surface
to extend from substantially a mid-section between front and back
walls of said cushion rearwardly to a location in the vicinity of
said back wall for relieving pressure against the bony prominence
of the buttocks of the person seated on said cushion.
7. The device of claim 6 wherein said cavity forming said pressure
relief means is devoid of foam material.
8. The device of claim 6 wherein the distance from said support
surfaces of said foam springs to said planar support surface varies
in accordance with the tapered thickness of said cushion.
9. The device of claim 6 wherein the thickness of said cushion
in the area of said cavity if about one-half that of the thickness
of the remainder of said cushion.
Wheel chair description
BACKGROUND OF THE INVENTION
The invention relates to a wheel chair cushion, and more particularly
to a patient retaining cushion for a wheel chair having pressure
distribution features to provide enhanced blood circulation and
reduce the possibility of decubitus ulcers.
Foam cushions have been utilized as wheel chair cushions including
foam cushions having what is commonly known as convoluted support
surfaces commonly found in mattress overlay products. It is also
known to make wheel chair cushions in the form of foam wedges to
help prevent the patient from sliding down in the wheel chair. U.S.
Pat. No. 4,646,374 discloses an orthotic sling seat cushion for
a wheel chair and the like which comprises an elongated foam wedge
having a substantially planar top surface. The bottom of the cushion
slopes progressively upward toward the top of the cushion to provide
the desired pelvic tilt when used on a sling wheel chair type seat.
Recently, the use of straps or other means of tying or securing
a patient within a wheel chair to prevent them from falling out
of the wheel chair have been greatly restricted. This leaves many
wheel chair ridden patients without an effective means of retention
in the wheel chair if they should lose control of their position.
U.S. Pat. No. 4,901,387 discloses the expedient of individual foam
springs with an upper trapezoidal profile and longitudinal and lateral
spacing in a mattress overlay whereby the foam springs act relatively
independently to disperse pressure.
Accordingly, an important object of the present invention is to
provide a pressure distributing and circulation enhancing cushion
for a wheel chair and the like having patient retention capabilities.
Another object of the invention is to provide a foam cushion for
a wheel chair and the like which is wedge shaped for patient retention
yet has an enhanced pressure distribution and circulation enhancing
upper surface comprised of individual foam springs.
Another object of the present invention is to provide an improved
patient retaining wheel chair cushion constructed from foam rubber
having enhanced pressure relief features for reducing decubitus
ulcers.
SUMMARY OF THE INVENTION
The above objectives are accomplished according to the present
invention by providing a foam cushion having a base and an upper
support surface with longitudinal and lateral air channels defining
individual foam springs. The foam springs have support surfaces
which are inclined to the base of the cushion so that the supporting
surfaces of the foam springs line in a plane inclined rearwardly
for patient retention. The foam springs act individually for distributing
pressure over the occupant's body and cushion while a cavity in
the base surface provides pressure relief in the rearward half of
the cushion.
DESCRIPTION OF THE DRAWINGS
The construction designed to carry out the invention will hereinafter
be described, together with other features thereof.
The invention will be more readily understood from a reading of
the following specification and by reference to the accompanying
drawings forming a part thereof, wherein an example of the invention
is shown and wherein:
FIG. 1 is a perspective view of a wheel chair cushion constructed
in accordance with the present invention;
FIG. 2 is a perspective view taken from the bottom of a wheel chair
cushion constructed according to the invention;
FIG. 3 is a side elevation of a wheel chair cushion constructed
in accordance with the present invention with a person seated on
the seat of a wheel chair;
FIG. 4 is a sectional view taken along line 4--4 of FIG. 1;
FIG. 5 is an enlarged perspective of a part of a wheel chair cushion
constructed in accordance with the present invention illustrating
individual foam springs; and
FIG. 6 is a partial top plan view of a wheel chair cushion constructed
in accordance with the present invention.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT
Referring now in more detail to the drawings, a foam cushion, designated
generally as A, is provided for a mattress, cushion, and the like
constructed from polyurethane foam such as 1.4-3.0 density foam
material with an ILD in the 30 to 40 range. The cushion is constructed
having an overall thickness of approximately 3.75 inches at a front
wall 8a, and a thickness of 2.75 inches at a rear wall 8b providing
a rearwardly tapered wedge shape to provide cushioning and support.
Individual foam springs, designated generally as B, have a square
cross-section of approximately 11/2 inches and a height of approximately
11/4 inches. Channels of approximately 1/4 inch wide are formed
in the foam material longitudinally and laterally to isolate each
foam spring and provide air circulation. In addition to supporting
and cushioning a person's body, the cushion provides redistribution
of body weight to reduce pressure at strategic points of the body
and reduce the formation of decubitus ulcers in the case of prolonged
sitting when used by a medical patient. The chemistry and performance
of the foam material may vary depending on the application being
made. For wheel chair use, foam having a density of 2.5 and ILD
of 45 is preferred. However, the invention may have utility in seats,
geri-chairs, and dialysis chairs, etc.
As can best be seen in FIGS. 1 and 2, cushion A includes a rectangular
foam base C on which a plurality of individual foam springs B are
carried. Each foam spring includes a rectangular base block 10 and
a horizontally planar support surface 12 at a correct level for
support. A converging solid body in the form of a polyhedron 14
extends between base block 10 and planar surface 12. Polyhedron
14 includes 4 trapezoidal planar faces 16 which converge upwardly
to planar surface 12. Preferably, the base of polyhedron 14 co-extends
with the perimeter of base block 10.
As can best be seen in FIGS. 4 and 6, there are a plurality of
longitudinal air channels 20 and lateral air channels 22 surrounding
each individual foam spring B. Channels 20, 22 are dimensioned sufficiently
so that foam springs B may act individually and together in groups
to support, cushion, and relieve body pressure in an effective manner.
For example, channels 20,22 preferably have a width of approximately
1/4 inch while a width in the range of 1/8 to 3/8 inch may be used.
The height of the foam spring for consumer use may vary, for example,
from approximately 1 to 11/2 inches. In one embodiment, a foam material
of 1.4 to 1.5 pounds was used. The combination of geometric design,
individualized foam springs, and density of foam material has been
found to provide a highly effective foam cushion for cushioning,
supporting, and reducing pressure while seated in a wheel chair
and the like. Support surfaces 12 provide the correct level of support
to the different parts of the seated buttocks. The channels enable
the foam springs to act individually and independently or in groups
to support the heavier parts of the body. These individual springs
can move in any direction without interfering with each other in
a horizontal plane to significantly reduce pressure against the
skin. In essence, the body is cushioned and moves with the surface
as opposed to being moved against the surface which creates shearing
or abrasion pressure on the skin.
As can best be seen in FIG. 4, the support surfaces 12 of foam
springs B lie in a plane which is inclined to the plane of a bottom
surface 34 of base C. This assists in retaining the patient in the
wheel chair. The bottom 22a of lateral channels 22 preferably vary
in distance from a bottom surface 34 of base C, as can best be seen
in FIG. 4. The bottoms 20a of longitudinal channels 20 preferably
are inclined to bottom surface 34 of base C at an angle generally
equal to the angle of inclination of the plane in which support
surfaces 12 lie.
As can best be seen in FIGS. 2 and 4, pressure relief means D formed
in base C relieves pressure in the critical area of the buttocks
of the person seated on the cushion which includes the area of bony
prominence. Pressure relief means D includes a cavity 30 in the
form of a rectangular cut-out or void of foam material. Cavity 30
is underneath the rearward portion of the cushion formed substantially
in its entirety rearward of the mid-section of the cushion, as can
best be seen in FIG. 4. This places the bony prominence of the buttocks
of the person seated on the cushion directly over pressure relief
cavity 30. Foam springs B in the area 32 directly above cavity 30
have increased resiliency and compression due to the cavity. This
provides two important functions. First, it relieves pressure against
the heavier portions and bony prominence of the buttocks to distribute
pressure more evenly over the remaining portions of the person's
buttocks when seated on the cushion, and it allows the top of the
cushion to be more depressed resulting in a more concave opening
in which the occupant's buttocks conforms. This assists in retaining
the occupant in the wheel chair due to the frictional engagement
of the cushion with the wheel chair and the dipping of the patient
with the cushion. All of the foam springs resiliently engage to
frictionally grip the person seated on the cushion, and, together
with the wedge shape of the cushion, effectively assist in retaining
the person in the wheel chair.
While a preferred embodiment of the invention has been described
using specific terms, such description is for illustrative purposes
only, and it is to be understood that changes and variations may
be made without departing from the spirit or scope of the following
claims. |