Wheel chair abstract
A frame for a collapsible wheel chair which permits custom tailoring
of the chair to the size of the invalid with only minor modifications.
The frame includes telescoping front posts which support horizontally
extending arms to which a flexible seat is secured. A pair of cross
struts are provided which are rotatably secured to the horizontally
extending arms and to the bottom struts of the frame. When the chair
is collapsed by bringing the two sides of the chair frame together,
the telescoping post permits the horizontal arms to raise a distance
determined by the length of the cross struts. Thus, during manufacture,
the only parts that need be custom made to accommodate differing
sized invalids is the length of the cross struts.
Wheel chair claims
What is claimed is:
1. A frame for a folding-type wheelchair comprising, in combination:
(a) first and second side members, each including
1. a tubular bottom strut,
2. a rear tubular strut fixedly attached to said bottom tubular
strut and extending upwardly therefrom,
3. a first front tubular strut fixedly attached to said bottom
tubular strut and extending upwardly therefrom for a predetermined
distance,
4. a tubular top strut having first and second ends, said first
end slidably engaging said rear tubular strut, said top strut extending
forwardly therefrom and being aligned substantially parallel to
said bottom strut,
5. a second tubular front strut coupled to said second end of said
tubular top strut and extending downward therefrom a predetermined
distance, and
6. a tubular member having an outer diameter less than the inner
diameter of said first front tubular strut and an inner diameter
greater than the outer diameter of said second front tubular strut,
said tubular member being telescopically inserted into said first
front tubular strut and said second front tubular strut being telescopically
inserted into said tubular member;
(b) a first tubular cross member rotatably coupled to the bottom
tubular strut of said first side member and to the tubular top strut
of said second side member; and
(c) a second tubular cross member rotatably coupled to the bottom
tubular strut of said second side member and to the tubular top
strut of said first side member, said frame further including, a
first cylindrical bushing disposed between said tubular member and
said second front tubular strut;
a second tubular bushing disposed between said tubular member and
said first front tubular strut; and
a slide member secured to the lower end of said second front tubular
strut, said slide member having a diameter slightly less than said
inner diameter of said tubular member;
said first and second bushings and said slide member being formed
from a nylon plastic material;
and a third tubular bushing disposed between said tubular member
and said first front tubular strut and secured to the lower end
of said tubular member by a pin passing diametrically through said
tubular member and into said third tubular bushing.
Wheel chair description
BACKGROUND OF THE INVENTION
I. Field of the Invention
This invention relates generally to the design of a wheel chair
frame and more specifically to a folding-type wheel chair frame
having a portion thereof supported by telescoping posts which thereby
enables the width of the chair to be adjusted, while continuing
to use conventional "X" cross members to permit collapsing
of the chair in a single assembly.
II. Description of Prior Art
A typical prior art collapsible wheel chair frame over which the
present invention is deemed to be an improvement is described in
the McClintock U.S. Pat. No. 3,331,614. The frame of the McClintock
Patent comprises first and second sides coupled together by pivoting
cross members. The cross members connect from a bottom strut on
a first side to a vertically moving seat support member on the opposite
side. The chair is collapsed by moving one side towards the other
and in doing so, the seat support rails on either side move upward.
A means is provided for the invalid to adjust the width of his chair
by turning a crank operated threaded screw which couples the slidable
seat frame to the stationary arm rests.
It is to be especially noted that in the frame design disclosed
in the McClintock Patent the height of the seat is inversely related
to the width of the chair. That is, the wider the chair, the lower
the seat and vice versa. It is also to be noted that the height
of the arm rests with respect to the seat is also a function of
the chair width.
Because of the dimensions of the human body, for maximum comfort,
the distance between the arm rests and the seat should remain constant
independent of the overall width of the chair. Then too, most invalids
prefer not to sit too high in the chair because of a fear of tipping
due to the high center of gravity.
The wheel chair frame designed in accordance with the teachings
of the present invention allows the seat height with respect to
the arm rests to remain constant independent of chair width when
in its operable position. Furthermore, the seat height with respect
to the ground also remains constant. However, when it is desired
to collapse the folding wheel chair for transportation or the like,
this can be accomplished quite readily.
SUMMARY OF THE INVENTION
The collapsible wheel chair frame of the present invention comprises
first and second sides which are identical in construction to one
another and include horizontal bottom struts to which front and
rear vertically extending posts are connected. The front post of
each side includes a telescoping member which adjustably connects
the seat supporting rails which are adapted to slide up and down
with respect to the rear posts or struts. Cross members pivotally
secure the bottom strut of a first side to the seat supporting rail
of the opposite side such that the chair can be collapsed, irrespective
of the length of the cross members which are custom designed in
length to accommodate the size of the invalid who will be using
the chair.
When the chair using the frame of the present invention is in its
operative position to transport an invalid, the seat will be a pre-designed
distance below the level of the arm rests and above the ground.
Thus, many different chairs having identically constructed side
members can be built to accommodate a variety of wheel chair patients
of differing stature and the only custom made parts of the frame
are the cross members. Accordingly, manufacturing costs can be reduced
while still providing a wheel chair frame which is designed for
maximum comfort of a wide variety of invalids.
Other objects and advantages of the invention will become apparent
to those skilled in the art from a reading of the following detailed
description of the preferred embodiment taken in conjunction with
the accompanying drawings in which:
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of the wheel chair frame;
FIG. 2 is a front elevation of the wheel chair frame in a partially
collapsed position:
FIG. 3 is a front elevation view of the preferred embodiment with
the frame in its fully extended position;
FIG. 4 is an enlarged detailed view of the telescoping front strut
members used in the frame of FIG. 1; and
FIG. 5 is a cross-sectional view of the front strut member of FIG.
4.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring first to FIG. 1, there is shown a perspective view of
the structural elements comprising the collapsible wheel chair frame
of the present invention. As is illustrated, the frame, indicated
generally by numeral 10, is comprised of two side members 12 and
14 which are identically constructed. Hence, only the details of
the side 12 will be described, it being understood that the description
applies equally to the construction of side 14. The side 12 includes
a tubular bottom strut 16 which may be formed from aluminum or other
suitable metal. Welded to or otherwise affixed to the bottom strut
16 at a point 18 is a vertically extending back strut 20, also fabricated
from extended metal tubing, which is disposed generally at right
angles to the bottom strut 16. The rear tubular strut 20 is designed
to be of a suitable length and an upper segment 22 thereof is bent
slightly rearward at the point 24 and extends a second predetermined
distance upward and backward where it is bent at point 26 to provide
a handle grip area 28.
Also welded or otherwise affixed to the tubular bottom strut 16
is a L-shaped member 30 which connects to a first tubular front
strut 32. The front strut 32 projects upwardly from the horizontally
disposed leg of the L-bracket 30 for a predetermined distance.
A horizontally extending support rail 34 is connected between the
rear vertical strut 20 and the first tubular front strut 32. The
support rail 34 is also formed from an extruded metal tube and may
be welded in place or secured between the struts 20 and 32 by a
suitable fastening means (not shown). The side frame 12 further
includes a horizontally disposed moveable top tubular strut 36 which
is connected at a first end to a circular or C-shaped bracket 38
which either totally or partially encompasses the rear strut 20
so as to be slidable therealong.
Secured to the opposite end of the strut 36 is a tubular bracket
40, better shown in the enlarged view of FIG. 4. The tubular strut
36 passes through the bracket 40 in the manner illustrated. The
bracket 40, in turn, is welded to a second tubular front strut 42
which extends downward from the top strut 36 at substantially a
right angle. The length of the second tubular front strut member
42 is such that it telescopically engages the first tubular front
strut member 32. This telescoping arrangement is more clearly illustrated
in the crosssectional view of FIG. 5.
With respect to FIG. 5, it can be seen that the first tubular front
strut member 32 has an inside diameter of a sufficient size to receive
the outside diameter of an intermediate telescoping tube 44. The
inside diameter of the intermediate tube 44 is appropriately sized
such that the second front tubular strut member 42 may pass through
it.
In order to ensure smooth telescopic extension and compression
of the members 32, 42 and 44, a first cylindrical bushing 46 is
provided which is inserted in the space 48 between the inner surface
of the tube 32 and the outer surface of the tube 44. A second cylindrical
bushing 50 is secured to the lower end of the intermediate tube
44 by means of a pin 52 which passes diametrically through the tube
44 and into the cylindrical bushing 50. Similarly, a cylindrical
bushing 54 is disposed in the space 56 between the outside surface
of the tubular front strut 42 and the inside surface of the intermediate
tubular member 44. An end slide 58 is attached to the bottom end
of the strut 42 by any suitable means and maintains the tube 42
coaxial with respect to the axis of the intermediate tube 44.
The bushings 46, 50 and 54 as well as the end slide member 58 are
preferably formed from a plastic material such as nylon and are
dimensioned to permit a snug but slidable fit between the associated
mating members. The pin 52 passing through the tube 44 serves as
a stop for the second tubular strut member 42 when it is in its
collapsed position with respect to the tube 44 and further downward
force on the strut 42 will cause the intermediate tubular member
44 to be collapsed into the first tubular front strut 32.
Referring back to the pictorial view of FIG. 1, the frame 10 further
includes first and second cross struts 60 and 62. The cross strut
60 is rotatably affixed to the bottom strut of the side 14 and to
the top strut 36 of the side 12 by means of a tubular bracket 64
which surrounds the bottom strut of side 14 and a corresponding
tubular bracket 66 which is affixed to the other end of the cross
strut 60 to encompass the strut 36. In a similar fashion, the cross
strut 62 is rotatably coupled to the bottom strut 16 of the frame
side 12 and to the arm rail of the side 14. Again, tubular brackets
provide an excellent means of obtaining the desired rotational coupling.
Because the invention resides in the novel construction of the
frame, it is not deemed necessary to explain in detail the other
parts comprising the completed wheel chair. However, for ease of
visualization, the drawings of FIGS. 1, 2 and 3 depict by a phantom
line representation the manner in which the rear and front wheels,
the seat, and the seat back are disposed with respect to the frame
10.
As perhaps can best be seen in FIG. 2, the flexible seat pad represented
by phantom lines 68 is affixed at opposite ends to the tubular top
struts 36 on the frame sides 12 and 14. Also, the flexible seat
back 70 is attached by rivets, snaps, or otherwise to the rear struts
20.
Now that the details of the construction of the wheel chair frame
of the preferred embodiment has been described in detail, consideration
will next be given to its operation and to the various advantages
afforded thereby.
OPERATION
To obtain economies in scale in the manufacture of an item such
as a collapsible wheel chair, it is, of course, desirable to use
standardized parts, rather than having to custom make a wheel chair
to fit invalids of various sizes. However, where personal comfort
is concerned, it is not possible to design a standard size chair
for use by all individuals. For example, if a standard size chair
is made to accommodate an obese individual, its width may be too
great to comfortably contain a person of a slighter frame and vice
versa.
The present invention solves this problem by permitting standardized
parts to be utilized in the fabrication of the two sides 12 and
14 of the wheel chair. To accommodate individuals of differing widths
and to thereby customize the chair to the invalid, it is only necessary
to provide cross braces 60 and 62 of custom made length. As can
be seen from the front view of FIG. 3, it is the length of the cross
members 60 and 62 which determine the overall width of the chair
when it is in its fully extended position. By providing the telescoping
elements as the front vertical struts of the chair and by providing
a slidable connection between the top strut 36 and the rear struts
20, a chair of any given fully extended width can be collapsed,
irrespective of the length of the cross members 60 and 62.
FIG. 2 illustrates the wheel chair in its partially collapsed position.
Here, the sides 12 and 14 are forced together and in doing so, the
cross braces 60 and 62 rotate about the bottom struts 16 and top
struts 36 as the top struts 36 move upward and the telescoping elements
32, 44 and 42 are extended. By providing a double telescoping unit,
i.e., intermediate tubular member 44 within the lower front strut
32 and the upper front strut 42 within the intermediate member 44,
a significant extension can be obtained to permit the top tubular
struts 36 to slide sufficiently high up on the rear struts 20 so
that the collapsed width of the chair is a minimum.
In extending the chair frame, the side members 12 and 14 are pulled
apart from one another and this exerts a downward force on the top
tubular struts 36 through the action of the rotatable cross members
60 and 62. The downward force causes the top struts to slide downward
about the rear struts 20 and the telescoping elements 42 and 44
to be collapsed into the first front tubular strut member 32.
Thus it could be seen that the design of the present invention
permits wheel chairs of varying widths to be produced economically,
the only custom made parts being the cross members 60 and 62 as
well as the upholstery including the seat 68 and the back 70. The
side members 12 and 14, including all of the parts comprising same,
remain fixed independent of the width that the chair is being designed
for. It is also to be noted that the chair is no higher in its folded
position than it is when it is in its fully extended position. Hence,
storage, shipping and carrying in an automobile is facilitated.
While the invention has been particularly shown and described with
reference to a preferred embodiment thereof, it will be understood
by those skilled in the art that the foregoing and other changes
in form and detail may be made therein without departing from the
spirit and scope of the invention. |