Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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"A Wheelchair"
The invention relates to a wheelchair, and particularly to a collapsible
wheelchair.
Collapsible wheelchairs have been provided for some time, the objective being
to
allow them to collapse in a simple and compact manner so that they can be
easily
stored and transported, for example, by loading into the boot of a car.
One known collapsing arrangement comprises a scissors-type hinge between the
wheels which allows the chair to be collapsed by pushing the sides of the
chair
towards each other. The wheels may or may not be removable. In this
arrangement,
the seat is generally flexible so that it folds down as the sides are pushed
towards
each other. While this arrangement is usually quite simple to operate, it
suffers from
the disadvantage of the chair not being particularly compact when collapsed.
Also,
I S the seat is often not particularly comfortable because it is of a flexible
material to
allow folding as the chair is collapsed. A still further disadvantage is that
because the
hinging mechanism is at the core of the chair structure it reduces structural
strength,
particularly in the transverse direction. Further, over time play in the
structure can
arise due to wear.
Alternatively, as described in Soviet Union Patent Specification No. SU1814547
it is
known to provide a collapsing arrangement whereby the backrest support folds
down
over the seat. However, such chairs are still quite bulky when collapsed and
the
arrangement is of limited benefit.
Finally, a general problem with existing collapsible wheelchairs is that they
are quite
heavy, and thus diff-lcult to lift when collapsed.
The invention is therefore directed towards providing a wheelchair which is
collapsible in a manner whereby the chair is very compact when collapsed.
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Another objective is that the chair has a high structural strength.
A further objective is that the chair is relatively lightweight.
According to the invention, there is provided a collapsible wheelchair
comprising a
seat support, a backrest support, a lower leg support, and wheels on an axle,
characterised in that, the backrest support and the Iower leg support are each
movable from an operative position to a collapsed position substantially
parallel to
the seat support.
By allowing the backrest support and the lower leg support to lie
substantially
parallel to the seat support, the wheelchair collapses in a very compact
manner.
There is no need to introduce a hinge between the wheels and there is
therefore
improved structural integrity.
In one embodiment, the backrest support and the lower leg support are movable
by
pivoting about the seat support. Pivoting is a very simple way of collapsing
the
chair, and pivot joints are also generally very reliable and durable.
In one embodiment, the lower leg support is movable by pivoting about a lower
leg
support pivot joint to Iie underneath the seat support. This is a very simple
and
compact arrangement.
Preferably, the seat support comprises a front portion which extends
downwardly
and supports the lower leg support pivot joint at a lower end thereof. This is
an
important aspect of the invention as the front portion provides a large degree
of
strength and structural integrity for the front part of the chair, and it also
serves the
purpose of supporting a pivot joint for the lower leg support so that the
lower leg
support folds neatly up underneath the seat support in a compact manner. In
this
latter embodiment, the seat support front portion comprises a pair of spaced-
apart
longitudinal tubes extending downwardly.
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In one embodiment, the lower leg support is configured to lie between the
lower leg
support pivot joint and the wheel axle or camber bar. This allows the lower
leg
support to rest between the seat support front portion and the wheel axle in a
compact and convenient manner.
In one embodiment, the lower leg support pivot joint comprises a pivot pin
between
the lower leg support and the seat support, and a sleeve which is slidable
between a
locked position covering the pin and preventing lower leg support rotation and
an
unlocked position at which the pin is exposed and the lower leg support is
free to
pivot about the pin. The use of a slidable sleeve is a very inexpensive and
simple
way of locking the joint in a manner whereby the chair withstands the usual
day-to-
day forces transmitted from the front of the wheelchair.
Preferably, the sleeve is knurled for ease of operation. This allows a user to
easily
slide the sleeve between the locked and unlocked positions.
Preferably, the sleeve is held in the locked position by a bayonet fixture.
This is a
well-known and simple fixture.
Preferably, the lower leg support comprises a U-shaped bar, the lower part of
which
is a footrest. This is a simple construction which provides excellent strength
in a
simple and lightweight manner.
In one embodiment, the lower leg support further comprises a transverse brace
extending between uprights. Such a brace provides a large degree of strength
for the
lower leg support, particularly to prevent it from twisting. Again, the brace
does not
add much weight or complexity to the wheelchair.
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In one embodiment, the U-shaped bar uprights are mounted within a pair of
outer
sleeves for telescoping height adjustment. This is a very simple way of
providing
adjustment for the footrest.
Preferably, the seat support comprises a brace extending transversely between
a pair
of side members, and the lower leg support brace is offset with respect to the
seat
support brace when the chair is collapsed. These braces can allow a compact
arrangement whereby they provide support for the chair when collapsed so that
it is
not easily damaged.
In one embodiment, the wheelchair further comprises a fastener to interconnect
the
lower leg support and the seat support in the collapsed position to prevent
inadvertent opening. This is a simple way of preventing inadvertent opening.
The
fastener can, for example, be connected between the braces on the seat and
lower leg
I S supports.
Preferably, the wheel axle is mounted on an adjustable axle support for height
adjustment. This allows excellent versatility.
In one embodiment, the axle support comprises a pair of uprights
interconnected by
a transverse bar connected to the wheel axle. This arrangement provides high
strength in a simple manner.
In one embodiment, the axle is adjustable in the longitudinal direction on the
axle
support. This also provides versatility in a simple manner.
In one embodiment, the uprights are mounted for telescoping height adjustment.
This is a simple way of allowing height adjustment.
In one embodiment, the wheelchair further comprises a longitudinal brace
extending
between the lower leg support and the seat support, the longitudinal brace
being
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removable. Such a brace adds additional structural strength, which, for
example, is
desirable in some applications such as sports use.
In one embodiment, the backrest support is connected to the seat support by a
pivot
joint. Preferably, the backrest support comprises a lock having a pair of
locking pins
biased into a locked position and releasable by operation of an actuator. This
is a
very simple release arrangement.
In one embodiment, the backrest support comprises at least one plate extending
in
the longitudinal direction, each plate being connected to the seat support by
a pivot
joint and by a lock positioned rearwardly of the pivot joint and being secured
to a
backrest support main body between the joint and the lock. These plates
provide
high strength connecting the backrest and seat supports together, and allow
the
backrest support to be folded down to overlie the cushion of the seat support.
The invention will be more clearly understood from the following description
of
some embodiments thereof, given by way of example only with reference to the
accompanying drawings in which: -
Fig. 1 is a perspective view from above of a wheelchair of the invention;
Figs. 2a, 2b and 2c are diagrammatic side views illustrating the manner in
which the wheelchair is collapsed;
Fig. 3 is a side view of the wheelchair;
Figs. 4a, 4b and 4c are side views showing folding of a lower leg support in
more detail;
Fig. 5 is a side view showing folding of both a backrest support and a lower
Ieg support; and
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Fig. 6 is a perspective view showing the wheelchair when folded.
Referring to the drawings, there is shown a wheelchair 1. The wheelchair 1 has
a
frame 2 to which is connected a pair of wheels 3. The frame 2 comprises a seat
support 5, a backrest support 6, and a lower leg support 7. The seat support 5
and
the backrest support 6 support seat and backrest cushions, which are not shown
in
the drawings for clarity. The lower leg support 7 is connected to the seat
support 5
by a pair of joints 50 and the backrest support 6 is connected to the seat
support 5 by
a pair of joints 26.
The seat support 5 comprises a pair of longitudinal bars 10 which are
interconnected
by a rear brace 11, a front brace 12, and an axle 13. The wheels 3 are
connected to
an axle 13 by quick release couplings for ease of removal.
Briefly, the chair 1 collapses as shown in Figs. 2(a), 2('b), and 2(c). There
are no
joints which operate about a vertical axis, and so there is complete
structural rigidity
in the transverse direction. Also, in the longitudinal direction the seat
support 5
provides rigidity. The lower leg support 7 pivots about the joints 50 as shown
in Fig.
2(b). The joints 50 are at the end of a front portion of the seat support 5
which
extends downwardly. Also, the lower leg support 7 is configured to have a
length
which allows it fit neatly between the joints 50 and the axle 13. The fact
that the
joints 50 are spaced-apart from the main part of the seat support allows the
lower leg
support 7 lie substantially parallel to the seat support 5. Also, the backrest
support 6
has a pair of plates 25 which support the main part of the backrest support
rearwardly of the pivot pins 26. This allows the backrest support to lie
substantially
parallel to the seat support in a neat and compact manner, as shown in Fig.
2(c).
In more detail, and referring particularly to Fig. 3, the axle 13 is mounted
on a pair
of axle supports 14. Each axle support 14 has a lower horizontal support bar
15
which supports an axle clamp lb. The clamps 16 are movable between front and
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rear positions for versatility and balance adjustment. The lower support bar
15 is
connected to a pair of uprights 17 which engage within telescopic outer
sleeves 18
which have apertures for setting height using adjustment screws.
Referring particularly to Figs. 1 and 3, the backrest support 6 comprises a
pair of
uprights 24 which are fixed to the triangular plates 25 by a pair of bolts 27.
The
plates 25 are pivotally connected to the seat support bar 10 by pivot pins 26.
The
plates 25 are locked in the operative position by a pair of releasable locking
pins 28.
The locking pins 28 are spring-loaded and may be disengaged by pulling an
actuator
string 29, shown in Fig. 1. The backrest support 6 also comprises a transverse
brace
30.
Referring particularly to Figs. 1, 3 and 4, the lower leg support 7 comprises
a U-
shaped bar 35 within a pair of outer tubes 34. The lower part of the bar 35
acts as a
footrest. A forward footrest 36 is also connected to the bar 35 to provide
additional
feet support. A pair of castor sockets 37 are connected to the bars 34 and are
each
held in position by a fixing bolt 38 which prevents rotation and by a shoulder
on the
bar 34 which prevents upward movement. The socket 37 is connected to a castor
suspension bar 39, which in turn supports a castor 40. The suspension bar 39
is
rotatable within the socket 37. An important aspect of the lower leg support
is that a
Iarge degree of structural strength is provided by a transverse brace 45 which
extends
between the uprights of the U-shaped bars 34. This withstands forces exerted
at
individual castors 40, particularly twisting or rotational forces.
As stated above, the lower leg support 7 is connected to the seat support 5 by
a pair
of pivot joints 50. The front elbows of the longitudinal bars IO are turned
inwardly
to reduce width. Each pivot joint 50 comprises a knurled sleeve 51 which has a
cut-
out to form a bayonet fixture with a spigot 52 on the respective seat support
longitudinal bar 10. An important aspect of the seat support is that the
longitudinal
bars 10 extend dawnwardly at the front end to provide a large degree of
structural
strength for the seat support and the structure generally. Further, the
reduced width
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at the front allows the lower leg support 7 to fold upwardly under the seat
support in
a compact manner. The pivot joint 50 also comprises an internal pivot pin 53
between the bars 34 and the longitudinal bar 10 of the seat support 5.
In operation, and referring particularly to Figs. 2, 5 and 6 the wheelchair is
used in
conventional manner by a wheelchair user, with or without an assistant. To
collapse
the chair 1, the user or an assistant pulls the actuator 29 which releases the
spring-
loaded pins 28 to release the plates 25 and allow them to pivot about the seat
support
5. The backrest support 6 is then pushed forward so that it overlies the seat
support
5. The user or an assistant then rotates the knurled sleeves 51 to release the
bayonet
lock, and then slides the knurled sleeve 51 downwardly as shown in Fig. 4a to
expose
the pivot pin 52. The lower leg support 7 may then be easily folded upwardly
and
under the seat support 5 as shown in Fig. 4(c). The fully folded chair is
illustrated in
Fig. 5.
It will be appreciated from the drawing of Fig. 6 that the chair folds in a
very
compact manner. The plates 25 allow the backrest support 6 to be spaced-apart
from
the seat support so that the cushion of the seat support is easily
accommodated
within the backrest support brace 29. This cushion may alternatively be
removed.
Further, the front ends of the longitudinal seat support bars 10 allow the
lower leg
support 7 to lie parallel to the seat support to allow a compact collapsed
position. As
is clear from Fig. 6 the lower leg support is accommodated between the front
portion
of the longitudinal bars 10 and the axle supports 14. It is clear particularly
from Fig.
5 that the seat support brace 12 and the lower leg support brace 45 are offset
with
respect to each other so that they together provide support for the chair when
collapsed in a neat and compact folding arrangement. The wheels can be removed
either before or after folding the backrest and lower leg supports. These are
removed
in a conventional manner using a quick-release coupling.
It will be appreciated that the chair of the invention has a large degree of
structural
strength, while at the same time being of simple and lightweight construction
and
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also allowing very compact and simple collapsing. The fact that there are no
joints
operating about a vertical axis is very important as this provides complete
rigidity in
response to transverse and twisting forces. As is clear from Fig. 6, the chair
is very
compact when collapsed and may be easily fitted into the boot of a car.
Further,
collapsing is very simple to perform as it is only necessary to operate the
actuator
strings 29 and slide the knurled sleeves 51.
The invention is not limited to the embodiments described. For example, it is
envisaged that a lower leg support pivot joint may have a sleeve which is
locked by a
push-button arrangement instead of a bayonet fixture, however, the bayonet
fixture is
particularly convenient. It is also envisaged that an internal slidable rod
may provide
rigidity for the joint when locked. Alternatively any other type of lockable
joint
providing equivalent locking strength may be used.
Because the lower leg support is effectively cantilevered to provide an open
construction, it is envisaged that an additional brace arrangement may be
provided.
Such an arrangement may be removable so that it is used only for certain
applications such as sports. In one example, such a brace may be a
longitudinal
brace which connects with the lower leg and seat supports. This would provide
additional support for the lower leg support 7 and longitudinal support
generally.
Such a brace may be connected by quick-release coupling. The brace may be
telescopic for length adjustment. In one embodiment, the brace may extend
between
the brace 45 and the axle 13, or alternatively the rear seat support brace 11.
Alternatively, external struts across the elbows at the front portion of the
seat support
5 may be used. Another way of providing increased longitudinal strength is to
use a
particularly strong tubing at the front portion of the seat support, such as a
compound double-walled tube.
It is also envisaged that the lower leg support and/or the backrest support
may be
removable from the seat support such as by sliding out from telescopic
engagement.
