Note: Descriptions are shown in the official language in which they were submitted.
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This invention relates to a foldable wheelchair and more
particularly to a whee`lchair having a rigidly supported seat and
an extended wheelbase when unfolded.
Wheelchairs that are adapted to fold transversely are
well known in the art and commonly employ an X-frame structure
which is disposed intermediate a pair of sides, spacing the sides
apart and providing a base upon which a collapsible seat may be
mounted. The X-frame type of wheeLchair folds in a trans~erse
direction only and is therefore committed to a structure having a
fixed wheelbase dimension. The wheelbase of the chair is generally
kept as small as possible in order to provide a wheelchair of
compact dimensions. However, as a result of the shorter wheelbase,
the wheelchair tends to tip easily onto its front footrests. A
further drawback resulting from the shorter wheelbase occurs in
that the chair is caused to tilt back to an unstable position when
attempts are made to climb small curbs and steps. Additionally,
since pairs of front and rear wheels are generally used, on rough
terrain one of the rear wheels can lift up and lose contact with
the ground, thus making it impossible for a person seated in the
chair to propel it or to apply effective braking action.
Another form of foldable wheelchair structure that is
known in the art avoids some of the problems encountered with
the X-frame wheelchair structure. This wheelchair structure is
typified in United States patent No. 909,411, Hockney, issued on
January 12, 1909. The Hockney patent describes a wheelchair
with a pair of side-frames that are interconnected by means of a
split seat having a hinged centre joint and outer ends which are
hingedly connected to the side frames. A hinged split axle togeth-
er with a hinged split brace transversely interconnect the side
frames and a central rigid reach interconnects the intermediate
joints of the axle and brace. A free end of the reach carries a
single pivotally mounted wheeI at the rear of the wheeIchair. The
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chair is folded transversely and the wheelbase distance between
the rear wheel and the propelling wheeIs, which are~forwardly set
on the wheelchair frame, is reduced by pushing the reach into
the frame structure, causing the axle and brace to fold rearwardly
and the split seat to fold downwardly. Latching members are
provided to prevent accidental collapse of the wheelchair during
periods of use.
It may be seen that the Hockney wheelchair provides a
structure having an extended wheeIbase. However, the problems of
stability when climbing curbs and other raised obstructions are
not overcome by Hockney in view of the forward placement of the
propelling wheels and the rearward location of the single castor
wheel. Thus, it may be expected that instability occurs when the
front wheels are raised as when traversing an obstacle and the
weight is shifted back over the single castor wheel.
A further problem that may be expected with the Hockney
wheelchair may be seen in the central hinge structure of the split
seat. Thus, the integrity of the seat as a weight supporting member
depends entirely on the strength of the hinge and the strength of
the means used to connect the hinge to the seat.
An object of the present invention is to provide a
foldable wheelchair having an extended wheelbase to increase
stability.
Another object of the invention is the provision of a
foldable wheelchair that may be opened or folded without opening
or closing a locking latch.
A further object of the invention is to provide a wheel-
chair having rearwardly set propelling wheels, and a small wheeled
footrest at the front of the chair to effectively provide only
three points of contact between the wheels and a supporting surface,
thus ensuring that the rear wheels will always have traction.
The aforenoted disadvantages of the prior art may be
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substantially overcome and the objectives achieved by recourse
to the present invention which is a foldable wheelchair frame
that includes a pair of sides arranged in spaced parallel
relation, each having a rearwardly disposed outer portion
adapted to carry a wheel spindle. The frame also includes seat
support means disposed transversely between the sides, the
support means having an upper surface adapted to support a
seat, first free ends flexibly connected to opposed first
portions of the sides and a first flexible joint intermediate
the free ends which permits the support means to fold rear-
wardly when the sides are drawn together. A seat is disposed
transversely between the sides above the support means. The
seat has second free ends flexibly connected to opposed second
portions of the sides and a second flexible joint intermediate
the second free ends which permits the seat to fold upwardly
when the sides are drawn together. A bar is securably carried
by the first flexible joint and is adapted to be longitudinally
displaceable forwardly out of and rearwardly into the frame so
that rearward dispacement of the bar draws the sides together
and folds the support means and seat.
The invention will now be further described with
reference to embodiments thereof shown, by way of example, in
the accompanying drawings wherein:
Fig. 1 is a perspective view of a foldable wheelchair
according to the present invention;
Fig. 2 is a perspective view of seat support means
used in the embodiment of Fig. l;
Fig. 3 is a partial end view, which is partially in
cross-section, ofthe wheelchair ofFig.l taken alongthe linesA-A.
Fig. 3 is a sectional view taken along the lines B-B
of Fig. 2;
Fig. 5 is a perspective view showing the wheelchairof
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Fig. 1 in a partly folded configuration;
Fig. 6 is a perspective view of another embodiment for
a side frame in the wheelchair of Fig. l;
Fig. 7 is a perspective view of a clip used to flexibly
connect the seat to the frame of the wheelchair shown in Fig. l;
and
Fig. 8 is a side view of a portion of the embodiment of
Fig. 6.
A perspective view of one embodiment of the invention
is shown in Fig. 1 which includes a frame 10 having a pair of sides
12 that are spaced apart in substantially parallel relation. It
is seen that each side has a rearwardly disposed outer portion
adapted to carry a wheel spindle 13 on which is rotatably mounted
a rear wheel 14. Above the spindle 13 it will be noted that each
side 12 includes an upstanding backrest support member 15 that
is rearwardly inclined a slight amount. A flexible backrest 16
is shown suspended between the members 15. The backrest 16 may
be fabricated on any suitable material such as leather, heavy
fabric or the like.
A handbrake 17 is shown pivotally mounted on a lower
front portion of the side 12 and is located forwardly of the wheel
14 at a position where it can operably engage the wheel. A second
handbrake 17 (not shown) is located on the opposite side.
The sides 12, including a pair of arm ~b~ 12', may
be fabricated from bar, rod or sheet stock depending upon
appearance requirements and other design criteria such as weight
and strength as well as availability of materials. Although the
frame 10 is shown fabricated from solid rod stock, another
embodiment will be later described in which sheet stock material
is used.
A seat support 18 is shown disposed transversely between
the sides 12 in Fig. 1. The seat support 18 is shown in enlarged
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detail in Fig. 2 and Figs. 3 and 4 show particular aspects of its
structure which are not readily apparent from the other figures.
Above the seat support 18, a seat 20 is disposed
transversely between the sides 12. It will be seen that the seat
20 is formed of two rectangular panels 21 having inner ends which
are flexibly interconnected by a butt hinge 22. The free outer
ends of the panels 21 are flexibly secured to predetermined
portions of the sides 12 by way of clips 23. A perspective view
of a clip 23 is shown in Fig. 7.
A cushion 24 is provided to fully cover the seat 20.
In order to prevent obscuring details of the wheelchair structure,
only a corner portion of the cushion 24 is shown.
A bar 25 is shown in Fig. 1 connected to the seat
support 18 and a tee portion 26 of the bar 25 which extends
forwardly of the wheelchair and below the seat support 18 is
secured to a narrow, wheeled footrest 27. The tee portion 26 is
connected to the bar 25 via a vertical bar 25' that is adjust-
able in height to accommodate the length of an individuals' legs.
A pair of castor wheels 28 are connected to opposite ends of the
tee portion 26. It will be observed that each castor wheel 28
includes a stem portion 29 that is disposed in a direction
perpendicular to the surface supporting the wheelchair. Such
positioning of the stems makes it easier to pivot the wheelchair,
especially on loose material such as sand, gravel, and carpeting.
Referring now to Figs. 2 and 3, the seat support 18
is shown in greater detail. For example, it will be seen that
the bar 25 includes a longitudinal portion that is fixedly
carried by the seat support 18 and is displaceable in the
directions of the arrow 39. The seat support 18 is shown to
comprise a pair of longitudinal members 19 that are arranged in
spaced, substantially parallel relation transverse to the bar
25. Each member 19 includes two half portions, each in the form
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of an upstanding rectangular panel 30 having inner ends 31
which are adapted to form a double hinged joint with an upper
strap 32, a lower strap 33 and a pair of nuts and bolts 34 and
35 respectively. The bar 25 is welded to the straps 33. Each
inner end 31 is suitably recessed at the corners to permit free
movement about the ends of the straps 32 and 33. In addition,
the upper recessed portions of the inner ends 31 allows the upper
strap 32, together with the bolts 34, to be mounted below an
upper surface 35 of each panel 30, which upper surface engages
a corresponding lower surface of each panel 21 when the seat 20
is opened flat in its distended position.
A free outer end 36 of each panel 30 is adapted to form
a hinge joint in combination with portions of the sides 12 as
shown in Fig. 1. This feature is more clearly illustrated in
Fig. 3. Bolts 37 pass throughsuitably bored portions of the
sides 12 and the ends 36, and are held in place with nuts 38.
The panels 30 of Figs. 2 and 3 are shown to have
cylindrically formed ends 31 and 36. In the embodiment illustrated,
such ends are welded to each panel 30 and are then bored through
to provide a passageway for the bolts 34 and 37. The purpose of
the cylindrical form is to provide sufficient material following
the boring operation so as to not unduly weaken the ends. However,
in the event that smaller diameter h~gh tensile strength bolts
are used, the cylindrical configuration of the ends could be
dispensed with and the ends retained in a plain square-edge
configuration. This structural modification is illustrated in
Fig. 6 which shows a portion of one side of a second embodiment
of the invention.
The components illustrated in Fig. 6 include a solid
side 40 that is fabricated from sheet stock material such as
plywood, metal or plastic. Only one seat panel 21 is shown in
order to more clearly present the structural members of that side.
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The seat panel 21 is raised upwardly and is shown to be secured
to an inner surface of the side 40 by means of a butt hinge 22'.
A similar hinge 22 is shown fixedly secured adjacent the inner
end of the panel 21. A pair of upstanding seat support panels
42 are disposed in openings 43 and are secured vertically in
the sides 40 by way of long bolts (not shown) that fit in holes
45 as shown in Fig. 8. For the same reasons as described in
connection with the panel 30, the upper and lower inner corner
of each panel 42 is recessed to provide clearance for the head and
nut of the bolt 34 and to prevent interference with the upper
surface 3S when it supports the seat 20.
Fig. 3 is a front elevation taken along the lines A-A
of Fig. 1 and shows that the sides 12 diverge outwardly from the
bottom to the top of the frame 10. There are two reasons for such
divergence in the structure, one of which is to compensate for
the flexibility of the materials used which is exhibited when
a person is seated in the wheelchair. It has been observed that
under loaded conditions the seat support 18 tends to sag slightly.
This effect is compensated by diverging the sides 12 outwardly as
shown in Fig. 3. When the seat 20 is loaded, pressure is applied
to the upper surfaces 35 of the panels 30 causing the panels to
deflect downwardly and to draw in the sides 12 to a substantially
perpendicular position.
The straps 32 and 33 are formed with a slight bend as
shown which corresponds to the angle at which the upper surfaces
35 are set relative to the supporting surface of the wheelchair.
The purpose of this configuration is to prevent binding between
the contacting portions of the ends 31 and the straps 32 and 33
when the chair is unloaded as occurs when the chair is either
folded or opened to its distended configuration. While some bind-
ing will occur when a person is seated in the chair, this is of
no consequence and~;n fact helpful since it would serve to lock
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up the seat support 18 to prevent undesirable movement.
The second reason for introducing outward divergence
of the sides 12 is to obtain a wheelchair structure that is
easily folded. Such divergence, therefore, assists in avoiding a
dead spot in the frame structure which would impede folding the
chair. This-would otherwise occur if the panels 21 were arranged
to be absolutely flat when the wheelchair is fully distended.
In the flat seat configuration, moving the bar 25 rearwardly of
the frame 10 would not initiate the folding procedure since the
panels 21 are not biased in a direction to allow easy upward
movement of the butt hinge 22 with subsequent downward folding
of the panels 21. The panels 21 must first be lifted. This
disadvantage is avoided by slightly raising the inner ends of
the panels 21 relative to the outer ends which are secured to
portions of the side 12 by means of the clips 23. This arrangement
effectively biases the hinged portion of the seat 20 which is
intermediate the hinged outer ends of the seat and allows the
frame 10 to fold readily when the bar 25 is longitudinally dis-
placed rearwardly into the frame 10. There is of course no
difficulty experienced when the seat 20 is loaded since the
entire structure is locked up and held in place by the weight of
an individual on the seat.
Fig. 4 is a plan view, partly in cross-section, of
the front portion of the seat support 18 which is adjacent the
tee portion 26 of the bar 25. The portion of the seat support
18 that is illustrated is shown in its fully distended position,
that is with the sides 12 fully separated to their maximum dis-
tance and the bar 25 drawn forward fully in the direction indicated
by the arrow 39'. It will be observed that the panels 30 are
not aligned coaxially but rather are offset with respect to the
coaxial axis which is represented by a broken line 45. Thus,
whereas the hinged joints of the free ends 36 are located on the
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axis line 45, the hinged joints of the inner ends 31 are located
behind the line 45 in the direction of the rear of the frame 10.
The purpose of this arrangement is two-fold. Firstly, it assures
that the bar 25 can only be pushed rearwardly into the frame 10
between the sides 12 and not pulled outwardly out of the frame
10 as would occur if the panels30were arrangedin longitudinal
alignment. Accordingly, as the bar 25 is drawn forwardly in
the direction of the arrow 39', the sides 12 move outwardly from
the centre of the wheel chair until a lock-up condition is reached.
Since this occurs before the ends 31 reach the axis 45, it is
apparent that further forward movement of the bar 25 is not
possible but that rearward movement of the bar may occur to fold
the chair. The configuration of the rear portion of the seat
support 18 is the same as that of the front portion shown in
Fig. 4 and has been omitted merely to avoid a duplication of
description.
The other reason for arranging the panels 30 of the
seat support 18 as shown in Fig. 4 is to provide the aforenoted
lock-up feature without including separate latches or rule-type
hinges in the hinged joints to limit rotation. In this way,
a more simple construction is obtained and manual dexterity on
the part of the wheelchair user is not required to operate
latches.
Fig. 5 shows the wheelchair embodiment of Fig. 1 when
it is in a partially folded condition. Some portions of the
embodiment of Fig. 1 have been removed to simplify the illustra-
tion. The bar 25 has been displaced rearwardly in the direction
of the arrow 39" causing the panels 30 to pivot about their
respective end hinges and to fold rearwardly of the frame 10.
Concurrently, the ends of the panels 21 pivot about their respec-
tive hinges causing the butt hinge 22 to rise and the panels 21
to fold upwardly. The sides 12 are thus drawn together and the
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wheelbase distance between the castor wheels 28 and the rear
wheels 14 is reduced as the foot rest 27 is drawn between the
sides 12. Because of the structural arrangement described in
biasing the seat 20 and the seat support 18, the same effect
is readily obtained simply by pushing the sides 12 together.
In opening the wheelchair to its fully distended pos-
ition, it is required to draw the sides apart. The same effect
is achieved by bearing down on the seat 20. Either action separ-
ates the sides 12 which straightens out the folded seat 20 and
the folded seat support 18 to their respective distended positions.
And, as the seat support 18 unfolds, the bar 25 is displaced
outwardly of the frame 10 bringing the footrest 27 forward to its
distended position and increasing the wheelbase of the chair to
provide improved stability.
A further advantage is attained-from the wheelchair
of the present invention through an esthetic improvement which
avoids the appearance of the prior art wheelchairs that have
been described as chromy, cagelike, a~d institutional as there is
no way to cover the metal frame completely with fabric to
resemble more contemporary office or home furniture. The
structural design of the chair of the present invention allows
side panels in the shape of contemporary "bucket"design that
allows the entire frame to be covered with fabric or upholstery.
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