Wheel chair abstract
A wheel-chair has a foldable frame structure (10) which is lockable
in the unfolded state and carries wheels (11, 12) and a back (13).
In the folded state, all fixed parts are folded up between the wheels
of the wheel-chair. The frame structure (10) is box-shaped and has
foldable set and bottom members (15, 17) and foldable front and
rear wall members (19, 20). These seat, bottom, front and rear wall
members are pivotally connected to side wall members (14). The seat
and bottom members (15, 17) consist of two parts and are folding
upwards and are mechanically interconneted by means of a central
wall (18) for common folding movements. The front and rear wall
members (19, 20) also consist of two parts and are mechanically
interconnected for common folding movements by means of a rod (22)
disposed underneath the bottom portion (17). The back (13) is also
made of two parts (26, 27) which are pivotally connected to the
rear edge of a respective part (15) of the seat member and extend
downwardly towards the bottom member (17) such that they can be
locked in the unfolded state by means of a locking device (37) provided
on the rigid member (22). The front and rear wall members (19, 20)
are angled rearwards in all positions of the wheel-chair. The large
wheels (11) of the wheel-chair have a driving ring (89) which can
be moved between an inner and an outer position and which is fixed
on the hub (60) of the wheel by means of leaf springs (90) and which,
when the driving ring is moved between said inner and outer positions,
passes an unstable position of maximum tension of the leaf springs.
Also, the large wheels (11) of the wheel-chair are provided with
disc brakes (80) the brake discs of which are connected to the frame
structure (10) of the wheel-chair by means of a rotation-inhibiting
pin member (87) and by means of a nut and screw thread (81, 83)
which, when a brake handle (86) is pivoted, will move the brake
disc (80) into frictional engagement with a braking surface (67)
on the side face of the hub (60) of the wheel.
Wheel chair claims
We claim:
1. A collapsible wheel-chair having a foldable frame structure
(10) which can be locked in the unfolded state and which supports
the wheels (11, 12) and the back (13) of the wheel-chair and which
comprises a box-shaped seat having side wall members (14) connected
to foldable seat and bottom members (15, 16; 17) and to foldable
front and rear wall members (19; 20), characterized in that the
seat and bottom members (15, 16; 17) are foldable upwards and each
consist each of two rigid, hingedly interconnected seat and bottom
portions, respectively, (15, 16; 17) and are mechanically interconnected
for common folding movements, that the front and rear wall members
(19; 20) are foldable rearwards and each consist of two rigid, hingedly
interconnected front and rear wall portions, respectively, (19;
20) and are mechanically interconnected by means of a rigid member
(22) extending underneath the bottom portion (17), and that the
back (13) can be raised and consists of two back portions (26, 27)
which are pivotally connected to the rear edge of a respective part
(15) of the foldable seat member (15, 16) and which in the unfolded
state of the wheel-chair extend downwards behind the rear wall member
(20) for releasably engaging a locking device (37) provided on the
frame structure.
2. Wheel-chair as claimed in claim 1, characterized in that the
wheels (11, 12) of the wheel-chair are connected to corner pieces
(53, 71) which are each disposed at the corner of a respective side
wall member (14) and connected to hinge pins (30, 31, 32) for the
rear wall, front wall and bottom portions (20, 19, 17).
3. Wheel-chair as claimed in claim 1 characterized in that the
front and rear wall members (19, 20) have a length exceeding the
width of the frame structure in the unfolded state and that the
two front wall portions (19) and also the two rear wall portions
(20) in the unfolded state of the frame structure are directed obliquely
rearwardly and make an obtuse angle with each other.
4. Wheel-chair as claimed in claim 1, characterized in that the
two back portions (26, 27) of the back (13) are adapted to abut
on the rear wall (20) with their parts extending downwardly behind
the rear wall member and prevent folding of the rear wall when the
back is in its raised position.
5. Wheel-chair as claimed in claim 1, characterized in that those
parts of the two back portions (26, 27) which are located below
the pivotal connection (28, 47) of the back portions with the rear
edge of the corresponding seat member (15) are obliquely cut (at
50) in a downward direction away from each other in order, during
the inital phase of an upward folding movement of the seat and bottom
members (15, 16; 17), to make it possible, in the plane of the back,
to move apart the parts of the back portions located above said
pivotal connection (28, 47), and that the mutually facing edges
of the two back portions above said pivotal connection have engagement
means (43-46, 48, 49) which in the fully unfolded state of the frame
structure engage with each other in order to prevent any relative
movement of the back portions (26, 27) at right angles to the planes
thereof.
6. Wheel-chair as claimed in claim 5, characterized in that the
engagement means (43-46, 48, 49) consist of complementary flanges
(43, 45, 48) and recesses (44, 46, 49) in the mutually facing edge
portions of the two back portions (26, 27).
7. Wheel-chair as claimed in claim 1, characterized in that the
locking device (37) for the back (13) is provided on a rearwardly
extending part of the rigid member (22) disposed underneath the
bottom member (17).
8. Wheel-chair as claimed in claim 7, characterized in that the
locking device (37) is fixedly mounted on the rigid member (22)
and that each back portion (26, 27) has a locking projection (38)
which in the fully unfolded state of the frame structure is in locking
engagement with the locking device (37) and prevents lowering of
the back and which, when the parts of the back portions (26, 27)
located above the seat member are moved apart in the plane of the
back, is moved out of said locking engagement to permit folding
the back.
9. Wheel-chair as claimed in claim 1, characterized in that the
two seat portions (15, 16) of the seat member are hingedly interconnected
by means of a hinge shaft (34) extending through a central recess
(36) on the seat member (15, 16) to serve as a handle (35) for lifting
the wheel-chair for folding and transporting it.
10. Wheel-chair as claimed in claim 1, characterized in that the
rigid member (22) provided underneath the bottom portion (17) has
an attachment (23) for or is connected to a footrest (24, 41, 42).
11. Wheel-chair as claimed in claim 1, characterized in that the
wheel-chair has two large wheels (11) and at least one small wheel
(12), the small wheel or wheels (12) being designed in a per se
known manner as castors and the large wheels (11) being disposed
at such a distance from the frame structure (10) that there is sufficient
space for the back portions (26, 27) between them and the frame
structure when the wheel-chair is in the folded state.
12. Wheel-chair as claimed in claim 11, characterized in that each
of the large wheels (11) of the wheel-chair has a driving ring (89)
which can be moved between an inner and an outer position.
13. Wheel-chair as claimed in claim 12, characterized in that the
driving ring (89) of each wheel (11) is connected to the hub (60)
of the wheel by means of at least three leaf springs (90) which
are provided substantially in the plane of the wheel and which in
their untensioned state have a length which is greater than the
difference between the diameter of the hub and the diameter of the
driving ring and which are maintained constantly tensioned in a
gently S-shaped state by means of a flexible connection (91) between
the wheel (11) and the driving ring (89) and which have such a length
and such an S-shape that when the driving ring (89) is pressed inwards
towards the wheel (11), they pass an unstable position of maximum
tension and thereafter urge the driving ring (89) against the wheel
(11).
14. Wheel-chair as claimed in claim 1 characterized in that it
has a brake disc (80) which is connected to the frame structure
(10) and which, by means of a brake handle (86), can be brought
into engagement with the side face of the associated wheel hub (60)
for braking the wheel (11).
15. Wheel-chair as claimed in claim 14, characterized in that the
brake disc (80) is connected to a nut (81) which in turn is connected
to the brake handle (86) and is in threaded engagement with a threaded
journal (83) fixed on the frame structure (10).
Wheel chair description
The present invention relates to a collapsible wheel-chair which
has a foldable frame structure which can be locked in the unfolded
state and which supports the wheels and the back of the wheel-chair
and which comprises a box-shaped seat having side wall members which
are connected to foldable seat and bottom members and to foldable
front and rear wall members.
Wheel-chairs of this type are known from several patent specifications,
e.g. Swedish patent specification No. 161,002, German Auslegeschrift
No. 1,176,315, British patent specification No. 711,448, and U.S.
patent specifications Nos. 2,522,729, 2,592,405 and 3,337,261. Most
of these collapsible wheel-chairs have a frame composed of a number
of rods which are pivotally interconnected, such that the wheel-chair
can be collapsed by the rods forming a hinge system. As a rule,
the seat and back portions are made of strong woven fabrics but
at least the seat portions have sometimes consisted of rigid components.
Although British patent specification No. 711,448 does not relate
to a collapsible wheel-chair but to a collapsible perambulator or
go-cart, the system is the same as in the above-mentioned wheel-chairs.
The known wheel-chairs have several drawbacks in common. In most
cases, they are quite heavy but, above all, they are rather bulky
also when folded up. Often, it is also necessary to remove different
parts before the chair can be collapsed, and the back portions made
of fabric are often uncomfortable for the person sitting in the
chair. Therefore, there is a demand for rigid panels as back portions,
which has not been practicable in known constructions. In many cases,
use has also been made of seats of woven fabric, this being also
uncomfortable. Some of the known constructions have used rigid seats,
but it has then been necessary to remove or raise these seats in
a separate operation before the wheel-chair is folded up. Another
drawback inherent in known collapsible wheel-chair constructions
is that a load affecting the back of the chair has given rise to
substantial stresses at the corners of the box-shaped structure
forming the frame or body proper. Such substantial stresses have
necessitated larger dimensions and, hence, have entailed a weight
increase of the construction.
One demand placed on present-day collapsible wheel-chairs is that
they should have a small width in the collapsed state, a contemplated
overall width being 15-25 cm, including the wheels. It is a further
desire that the wheel-chairs should have a smaller length in the
folded state than in the unfolded state. This has not been achieved
in known collapsible wheel-chair constructions.
One of the reasons why it has not been possible to achieve a small
width of known wheel-chairs when collapsed is that the wheels usually
have a driving ring which is mounted outside the wheel rim. This
driving ring projects outside the tyre and, therefore, has contributed
to an unnecessarily large width of the collapsed chair. One object
of the invention therefore is to provide a movable driving ring
for the two large wheels of the wheel-chair.
Another object of the invention is to provide a collapsible wheel-chair
which is provided with a rigid back which should preferably also
contribute to the stability of the wheel-chair when in the unfolded
or raised state. Yet another object of the invention is to provide
a wheel-chair which has great stability in the unfolded state but
also low weight and small size in the collapsed state.
Further objects of the invention will appear from the following
description.
The above-mentioned and other objects of the invention are achieved
if the collapsible wheel-chair of the type mentioned in the introduction
to this specification is designed as recited in the main claim.
Thus, the wheel-chair according to the invention has a foldable
frame structure which can be locked in the unfolded state and which
carries the wheels and the back of the wheel-chair. In the collapsed
state of the chair, all fixed parts are folded up between the wheels
of the wheel-chair. The frame structure is box-shaped and has foldable
seat and bottom members and foldable front and rear wall members.
These seat, bottom, front and rear wall members are pivotally connected
to the side wall members. The seat and bottom members consist of
two parts and are folding upwards and are mechanically interconnected
for common folding movements. The front and rear wall members also
consist of two parts and are mechanically interconnected for common
folding movements by means of a rod provided underneath the bottom
member. The back also consists of two rigid parts, each of which
is pivotally connected to the rear edge of a respective part of
the seat member and extends downwards towards the bottom member
so as to be lockable in the raised state by means of a locking device
provided on the rigid member. The front and rear wall members are
angled rearwards in all positions of the wheel-chair. The large
wheels of the wheel-chair have a driving ring which can be moved
between an inner and an outer position and which is fixed on the
hub of the wheel by means of leaf springs and which, when being
moved between said two positions, passes an unstable position of
maximum tension of the leaf springs. Further, the large wheels of
the wheel-chair are provided with disc brakes the brake discs of
which are connected to the frame structure of the wheel-chair by
means of a rotation-inhibiting pin member and by means of a nut
and screw thread which, when a brake handle for the brake disc is
pivoted, moves the brake disc into frictional engagement with a
braking surface on the side face of the hub of the wheel.
By designing the collapsible wheel-chair as recited in the main
claim, many of the above-mentioned shortcomings of known wheel-chair
constructions can be obviated. The distinctive features of the wheel-chair
according to the invention do not actually reside in the folding
arrangement of the different rigid components, for this is previously
known from many of the above-mentioned patent specifications, but
the novel features reside in how folding is achieved for the separate
seat and bottom members, the front and rear wall members and the
back, and in the provision of the rigid member which extends underneath
the bottom member and which mechanically interconnects the front
and rear wall members. The fact that this rigid member or rod interconnects
the folding front and rear wall members means that the rigid member
and, hence, the footrests optionally fixed thereon will be folded
up between the front wheels of the wheel-chair when this is collapsed.
In this way, the wheel-chair becomes compact by having a shorter
length in the folded state than in the unfolded state. The rod or
rigid member has a further function by supporting the lowered bottom
member lying in the horizontal plane and connected to the seat by
means of a connecting member which brings about the common folding
movements of the bottom and seat portions. Since the back portions
are each pivotally connected to the rear edge of a respective part
of the folding seat member, there is obtained a very good distribution
of the forces which are exerted on the back by the person sitting
in the wheel-chair. In addition, the back extends downwardly below
the pivotal connection with the seat member, and the downwardly
extending portions of the back are pressed against the rear wall
members which are thus held in place. By the releasable engagement
with the locking device provided on the frame structure, the back
is maintained in the raised position, which in turn means that the
unfolded wheel-chair will have the required stability and is locked
against unintentional folding-up.
In order to reduce the weight, it is advantageous in a wheel-chair
according to the invention to connect the wheels of the wheel-chair
to corner pieces which are each arranged at the corner of a respective
side wall member and connected to hinge pins for the rear wall,
front wall and bottom members. In this manner, the hinge pins of
the frame structure will directly transmit the loads to the corner
pieces and, thus, directly to the four wheels.
Optimum function of the collapsible wheel-chair is achieved if
the front and rear wall members are given a length which exceeds
the width of the frame structure in the unfolded state, such that
the two front wall members and also the two rear wall members will
be directed obliquely rearwards and make an obtuse angle with each
other when the frame structure is in its unfolded state. This design
of the front and rear wall members is especially advantageous in
combination with the measure of letting the two downwardly extending
back portions of the back abut on the rear wall so as to prevent
folding thereof when the back is in its raised position. The back
will then serve as a lock which prevents unintentional folding of
the foldable front and rear wall portions which, as stated above,
are interconnected by means of the rigid member extending underneath
the bottom member.
In order to facilitate the folding of the wheel-chair and to prevent
any relative movement between the two portions of the back in the
raised state thereof, it is particularly advantageous in a further
development of the invention if those parts of the two back portions
which are located below the pivotal connection of the back portions
with the rear edge of the corresponding seat member are obliquely
cut in a downward direction away from each other in order, during
the initial phase of an upward folding movement of the seat and
bottom members, to make it possible in the plane of the back to
move apart the parts of the back portions which are located above
said pivotal connection, and also if the mutually facing edges of
the two back portions above said pivotal connection have engagement
means which in the fully raised state of the frame structure engage
with each other in order to prevent any relative movement between
the back portions perpendicular to the planes thereof. The engagement
means may then preferably consist of complementary flanges and recesses
in the mutually facing edge portions of the two back portions.
The locking device for maintaining the back in the raised state
is preferably provided on a rearwardly projecting part of the rigid
member disposed underneath the bottom portion. The locking device
may then be fixedly mounted on the rigid member but may also be
movably mounted thereon. If the locking device is fixedly mounted
on the rigid member, each of the back portions preferably has a
locking projection which in the fully raised state of the frame
structure is in locking engagement with the locking device and prevents
lowering of the back and which, when the parts of the back portions
located above the seat member are moved apart in the plane of the
back, is moved out of said locking engagement to permit lowering
the back.
The shaft hingedly interconnecting the two seat portions of the
seat member may in an advantageous embodiment of the invention be
caused to extend through a central recess on the seat member, thus
serving as a handle for lifting the wheel-chair when folding it
up. To this end, it is most convenient to provide the back portions
with a corresponding recess, such that it is possible to grip the
handle once the back has been lowered.
As mentioned above, it is especially advantageous in the invention
if each of the large wheels of the wheel-chair has a driving ring
which can be moved between an inner and an outer position. In an
especially advantageous embodiment of the invention, this driving
ring is connected to the hub of the wheel by means of at least three
leaf springs which are provided substantially in the plane of the
wheel and which in their untensioned state have a length which exceeds
the difference between the diameter of the hub and the diameter
of the driving ring and which are constantly maintained tensioned
in a slightly S-shaped state by means of a flexible connection between
the wheel and the driving ring and which have such a length and
such an S-shape that, when the driving ring is pressed inwards towards
the wheel, they pass an unstable position of maximum tension and
thereafter urge the driving ring against the wheel.
The invention will now be described in greater detail hereinbelow
with reference to the accompanying drawings, in which:
FIG. 1 illustrates one embodiment of a collapsible wheel-chair
according to the invention seen from in front and in the unfolded
state;
FIG. 2 shows the same wheel-chair from the rear;
FIG. 3 shows the wheel-chair from the side;
FIG. 4 is a schematic perspective view of a frame structure included
in the wheel-chair;
FIG. 5 shows certain parts of the frame structure from above;
FIG. 6 shows the same parts of the frame structure from the side;
FIG. 7 is a side view of a rigid member included in the frame structure
and a footrest fixed thereon;
FIG. 8 shows the same member as in FIG. 7 from above;
FIG. 9 shows the wheel-chair obliquely from above and from the
rear and illustrates the commencement of a folding operation after
the back has been lowered;
FIG. 10 shows the wheel-chair from in front in the collapsed state;
FIG. 11 shows the back from in front in the raised state;
FIG. 12 is a section taken along the line XII--XII in FIG. 11;
FIG. 13 shows the back from the rear in the raised state;
FIG. 14 is a section taken along the line XIV--XIV
FIG. 15 is a section taken along the line XV--XV in FIG. 13;
FIG. 16 shows the back from the rear when the back portions have
been swung apart during unfolding or folding of the wheel-chair;
FIG. 17 shows parts of the large wheels of the wheel-chair partly
in axial section;
FIG. 18 shows parts of the wheel in a part sectional side view;
FIG. 19 shows two components included in the hub of the wheel;
FIG. 20 is a schematic section corresponding to FIG. 17 and illustrates
the two stable positions of the driving ring;
FIG. 21 shows one seat pad half for the seat in the wheel-chair
according to FIG. 1;
FIG. 22 is a side view of the seat pad shown in FIG. 21;
FIG. 23 is a perspective view of the wheel-chair in the unfolded
state;
FIG. 24 shows the collapsed wheel-chair from the side;
FIG. 25 shows the unfolded chair from above;
FIG. 26 shows the unfolded wheel-chair from below.
As illustrated in the drawings, the wheel-chair according to the
invention has a foldable frame structure 10 which can be locked
in the unfolded state and which carries large rear wheels 11 and
small front wheels 12, and a back 13. The frame construction is
box-shaped and has rigid side walls 14. The side walls are connected
to each other by means of a seat consisting of two halves 15 of
which FIG. 4 shows only the metal parts provided along the sides
and covered by a seat pad 16 which may consist of expanded, moulded
polyurethane. FIGS. 21 and 22 show one half of the seat pad 16.
The side walls 14 are also interconnected by means of a bottom
consisting of two hingedly interconnected parts 17. The bottom and
seat portions 15, 16 are connected to each other by means of a connecting
wall 18. The connections between the side walls 14, the seat portions
15 and the bottom portions 17 are achieved by the provision of a
hinge pin extending along each longitudinal edge of the box structure
10. Similarly, there are provided longitudinal hinge pins at the
connections between the seat 15 and the connecting wall 18, and
between the bottom 17 and the connecting wall 18. By the provision
of the connecting wall 18, an upward folding movement of the seat
15 will produce a corresponding movement of the bottom 17, such
that the side walls will be moved towards each other.
The side walls 14 are connected to each other also by means of
folding front and rear walls 19 and 20, respectively. The connections
between the side walls and the front wall and the rear wall, respectively,
are achieved by means of vertical hinge pins which are disposed
at the corners of the frame structure. The two parts of the front
wall and the rear wall, respectively, are connected to each other
by means of vertical hinge pins 21. These hinge pins are fixed to
a rigid member 22 which extends underneath the bottom 17 and has
at its front end an attachment 23 for a footrest 24 and at its rear
end a plate 25 to permit running the wheel-chair on the rear wheels
only, in which case the person pushing the chair exerts a pressure
on the plate 25.
The back 13 consists of two parts 26, 27 each of which is hingedly
connected to an associated seat member 15. The hinge connection
28 is located at the rear edge of the seat. As appears from FIGS.
2 and 4, the back members 26, 27 extend beyond the hinge pin 28
down to the rigid member 22 so as to engage, when in the raised
position, the rearwardly slightly angled rear wall 20 to prevent
it from folding rearwards. In order to maintain the back in the
raised position, it is possible to provide on the rigid member 22
either a fixed locking device or a movable locking device which
prevents lowering of the back.
As mentioned above, the front and rear walls each consist of two
hingedly interconnected parts. These two parts have a larger overall
length than the width of the frame structure in the unfolded state
thereof. This means that the front and rear walls are angled rearwards,
as illustrated in FIGS. 4 and 5, when the frame structure is raised.
Since the central hinge pins 21 of the front and rear walls are
connected to the rigid member 22, the two walls will jointly be
swung rearwards when the wheel-chair is folded up. Since the bottom
wall 17 is above the rigid member and, also, is connected to the
seat portions 15, 16, the frame structure can be collapsed. The
initial phase of the folding operation proceeds in such a manner
that the locking device for the back is first loosened either by
releasing a movable locking device or by a slight upward pull in
the seat, whereby the back portions will be moved apart, as is illustrated
in FIG. 16 and described in more detail hereinbelow. When the back
portions have been moved apart in this manner, they can be pivoted
about their respective hinge pins 28 so as to lie flat against their
respective seat portion, as illustrated in FIG. 9, whereupon the
continued upward pivotment of the seat and bottom portions can be
effected to finally collapse the wheel-chair as illustrated in FIG.
10.
FIGS. 4-6 illustrate all the hinge pin connections required for
collapsing the frame structure per se. The vertical hinge pins 21
have already been mentioned in the foregoing. These hinge pins serve
as connections between the rigid element 22 and the common hinge
lines for the front wall portions 19 and the rear wall portions
20, respectively. Further, mention has also been made above of the
hinge pins 28 which connect the back portions 26, 27 to the rear
edge of the associated seat portion 15. In addition to these hinge
pins, there are provided hinge pins 29 connecting the seat portions
15 to the upper edge of the side walls 14. At the lower edge of
the side walls, there is a hinge pin 30 connecting the bottom wall
portions to the side walls. At the front edge of the side walls
14, there are vertical hinge pins 31 connecting the side walls to
the front wall portions 19. At the rear edge of the side walls 14,
there is a further vertical hinge pin 32 connecting the rear wall
portions 20 to the side walls 14. At the connection between the
bottom portions 17 and the rigid central wall 18, there is a hinge
pin 33. At the connection between the seat portions 15 and the rigid
central wall 18, there is a hinge pin 34 of which a portion 35 serves
as a handle 35 for collapsing the wheel-chair and transporting it
when collapsed.
In order to make it possible to grip the handle 35, the seat pad
is provided with a recess 36, and the back is provided with a corresponding
recess 37. The seat pad 16 may consist of expanded polyurethane
and has at its rear edge a recess 38 engaging about a corresponding
flange (not shown) at the rear edge of the seat portion 15. The
front edge of the seat portion 16 is curved, and the entire seat
portion is cup-shaped so as to offer a comfortable surface to sit
on.
FIGS. 7-8 illustrate the rigid member 22 with associated parts
fixed thereon. In this case, the rear pressure plate 25 serves as
a movable locking device which is pivotally mounted on a journal
36 and has its locking member 37 facing upwards so that it can engage
the rear edge of the raised back 13 which has locking lugs 38 extending
into the space between the locking member 37 and the attachment
for the hinge pin 21. When the back is raised, the lugs 38 are thus
locked against both rearward and forward movement. At its front
end, the member 22 carries the above-mentioned attachment 23 for
the footrest 24. The footrest 24 is fixed on an angled rod 39 which
can be locked in different vertical positions by extending through
the tubular attachment 23. In order to permit adjusting it in different
vertical positions, there is a locking screw 40 in the form of a
wing nut. The footrest has two foot-supporting plates 41 which are
pivotally connected to the angled bar 39 by means of a hinge pin
42 such that the two foot-supporting plates can be raised and folded
up between the front wheels when the wheel-chair is collapsed.
The design and function of the two back portions will be described
in more detail hereinbelow with reference to FIGS. 11-16. As previously
mentioned, the back may consist of moulded, expanded polyurethane
and may then have suitable metal inserts, if so required for obtaining
sufficient strength. The two back halves 26, 27 are similar but
not fully identical. Differences exist at the mutually facing edges
of the long sides. As appears especially from FIG. 16, the back
half 26 has a projecting flange 43 the thickness of which corresponds
to approximately half the thickness of the back. The back half 27
has in a corresponding location a recess 44 which is complementary
to the flange 43 and leaves a back wall portion of approximately
half the thickness of the back wall. A corresponding flange 45 and
recess 46 are provided just above the tubular attachments 47 for
the hinge pins 28. In addition, the back half 27 has a flange 48
while the back half 26 has a mating recess 49, this flange and this
recess being designed in agreement with the flanges 43, 45 and the
recesses 44, 46, respectively.
At the lower end, the back halves are obliquely cut with oblique
portions 50 beginning at the attachments 47 for the hinge pins 28.
By the provision of these oblique portions 50, the two back halves
can be angularly moved with respect to each other while being in
the same plane. This appears from FIGS. 16. By such angular movement,
the engagement between the flange 48 and the recess 49 will be suspended.
This also applies to the engagement between the flange 43 and the
recess 44. In that these two flanges and recesses are disengaged
with respect to each other, the back portions can be lowered against
the seat 15, 16. Since the flanges 43, 48 and 45 are provided on
opposite back halves, these halves cannot move relative to each
other at right angles to their common plane when an engagement exists
between the different recesses and flanges.
If the locking engagement between the back and the locking device
on the rigid member 22 is brought about without the use of a movable
locking device, the angular movement of the two back halves can
be used for releasing the locking engagement. A comparison of FIGS.
13 and 16 shows that the two locking lugs 38 move towards each other
when the back portions are moved away from each other. By providing
a recess 51 outwardly of each lug 38 and designing the locking member
37 as two separate upwardly projecting metal pieces which are spaced
a suitable distance from each other, the recesses 51 can be moved
to a position opposite the metal pieces so that the back portions
can be lowered when in the position illustrated in FIG. 16. When
the back is lowered and the wheel-chair collapsed, the back will
be located between the seat and the wheels. If, as shown in this
embodiment, the wheel-chair has elbow-rests 52, the back portions
26, 27 will be located between the seat portions 15, 16 and the
elbow-rests 52 when the wheel-chair is collapsed. The elbow-rests
52 may be designed as loose members which are inserted in recesses
53 in the seat portions 15, 16 adjacent the hinge pins 29 (see FIG.
5).
As previously mentioned, the hinge pins at the edges of the side
walls 14 are interconnected by means of corner pieces. In FIG. 3,
there is shown a corner piece 53 which also serves as an attachment
for a pivot shaft for the front wheels 12 which are in the form
of castors and, hence, are pivotally connected to the corner piece
53 by means of a fork 54. Also, there is shown a corner piece 55
serving as a connection between the hinge pins 29 and 31. The other
two corners are designed similarly.
FIGS. 17-19 show the construction of the large wheels 11 of the
wheel-chair. The wheel 11 has a hub made up of a number of components.
The hub thus has a central portion 56 with three projecting ears
57. These ears are arranged for receiving screws 58 which at the
same time engages with ears 59 on an outer hub member 60. By means
of a spoke portion 61, the ears 59 are connected to an arcuate part
62 having at its ends groove and tongue members 63 and 64, respectively.
By means of these groove and tongue members 63, 64, the member 60
can cooperate with two further, similarly designed members, such
that a complete outer hub portion is obtained. The inner side of
the member 60 is provided with two ears 65 serving as attachments
for screws 66. An end cover 67 can be secured on either side of
the hub by the screws 58, 66.
The end covers 67 serve as inner attachments for spokes 68 which
are secured in a per se known manner to a rim 69 for a pneumatic
tyre 70.
In FIG. 17, there is shown a corner piece 71 forming the lower
rear corner attachment for the connection between the vertical hinge
pin 32 and the horizontal hinge pin 30 of the frame structure. This
corner piece serves at the same time as an attachment for a tubular
shaft 72. Into this tubular shaft extends a likewise tubular shaft
73 which at its outer end carries a ball bearing 74 by means of
which the hub is rotatably mounted on the shaft 73. To permit loosening
the wheel 11, there is a locking device comprising a press-button
75 which is outwardly biased by a spring 76. When the button 75
is pressed, a recessed portion 77 on the button is moved inwardly
to a position in front of locking balls 78, whereby these will be
free to move radially inwardly and, thus, come clear of a shoulder
79 on the inner side of the tubular shaft 72.
In order to permit braking the wheel-chair, there is a disc brake
consisting of an annular brake disc 80 which is fixed on a nut 81
engaging with a threaded tubular screw 83 which is rotatably mounted
on the outer side of the shaft 72. The tubular screw is rigidly
connected to a brake rod 84 which at its front end is pivotally
connected to a two-arm lever 85 having a brake handle 86 and being
pivotally mounted on the front lower corner piece 53. When pulling
the brake handle 86, the brake rod 84 will be moved backwards, whereby
the screw 83 will be rotated and the nut 81 displaced outwardly,
such that the brake disc 80 is moved into braking engagement with
the inner of the two hub covers 67. The brake disc 80 and the nut
81 are prevented from rotating relative to the frame structure since
the brake disc has a locking pin 87 engaging in a corresponding
hole 88 in the corner piece 71.
As earlier mentioned and as appears from FIGS. 18 and 20, the large
wheel has a driving ring 89. This driving ring can be moved outwards
to the position shown in full lines in FIG. 20 and inwardly to the
position shown in broken lines in FIG. 20. This inward and outward
movement of the ring can be performed with the aid of three leaf
springs which are fixed between the driving ring 89 and the hub.
The leaf springs are fastened in the hub by being inserted through
recesses in the arcuate part 62 between the two ears 65. The springs
will thus be held in place by means of the three screws 58 and 66
and the spoke-forming part 61 holding the springs pressed against
the inner side of the cover 67. Outside the hub, the springs extend
in a gentle S-shape out to the driving ring 89 in which they are
fixed in a suitable manner. Between the springs or the driving ring
and the spokes 68, there is a string 91 which restricts the distance
by which the springs can move outwardly when the driving ring is
moved to its outer position. The springs 90 have a length exceeding
the distance between the driving ring 89 and the hub. When moved
from the outer position to the inner position, the springs 90 will
pass a position of maximum tension where the fixing points of the
springs at the hub and the driving ring are opposite each other.
As appears from FIG. 20, the inner position is located inwardly
of the position of maximum tension, while the outer position is
outwardly of the position of maximum tension. By the provision of
the strings 91, the springs 90 will always be maintained tensioned,
also in the outer position. This imparts stability to the driving
ring, such that it will not tend to "wobble" when in the
outer position.
As will have been appreciated from the above, the hubs of the large
wheels may consist of extruded pieces of material which have been
cut to suitable lengths and in which grooves for springs can be
milled. In the mounting operation, the end walls 67 are mounted
to form flanges for attachments for the spokes 68. The springs 90
preferably are relatively wide and should have a certain distance
of anchorage to provide the required stability. The springs serve
as an overcenter mechanism by being constantly maintained tensioned
in the two extreme positions. In the inner position, the springs
are prevented from becoming completely untensioned in that the driving
ring is pressed against the spokes. In the outer position, complete
relaxation of the springs is prevented by the provision of the strings
91.
By the above-mentioned special design of the hub, it will be very
rigid. The end walls 67, together with the intermediate parts 60,
56, serve as a box girder giving the box substantial rigidity in
the transverse direction, whereby lateral movement is prevented
if an obliquely directed load on the wheels should occur.
Since the hub diameter of the wheel is large, there is obtained
a sufficient angle between the spokes and the rim in order to achieve
considerable stability. Also, since the hub has a large diameter,
it has been possible to give the disc brake a large diameter and,
thus, a high braking effect. The design of the hub is also advantageous
in that the hub can be made of but a few components which are simply
screwed together by means of a number of screws.
As appears from the above and as readily realized by the skilled
reader, the wheel-chair according to the invention offers many advantages.
Since the footrest 41 can be folded upwards, it will be easier for
the person using the chair to sit down and get up from the wheel-chair.
The folding construction also makes it possible to place the footrest
between the large rear wheels when collapsing the wheel-chair. This
appears from FIG. 3 where the footrest 41 and the rigid member 42
are illustrated by broken lines in their retracted position in the
collapsed state of the wheel-chair. As also appears from FIG. 3,
the overall length of the wheel-chair is reduced when collapsing
the wheel-chair. The overall length can be reduced by pivoting the
front wheels 12 half a revolution. As appears from FIG. 7, the footrest
is vertically adjustable and it may also be angularly adjustable
by providing a hinge connection between the downwardly directed
and horizontal parts of the angled rod 39.
Since the different corners of the frame structure have been designed
as corner pieces into which the different hinge pins extend, a rigid
construction is obtained. Moreover, the different parts will be
easy to mount. Further, the pivotal movement can be facilitated
by providing the sleeves of the different wall portions with plastic
bushings through which the hinge pins extend. In this manner, it
is possible to prevent direct contact between the hinge pins and
the parts made of metal.
In that the elbow-rests 52 have been designed as obliquely cut
pieces of material (see FIG. 3) and, moreover, have been inserted
in the recesses 53, it is possible to reverse the elbow-rests to
make them project rearwardly or forwardly if a different position
of the elbow-rests is desirable.
The seat portions 15, 16 rest on the upper edge of the front and
rear wall members 19, 20, this imparting great stability to the
seat. A downwardly directed pressure on the seat also entails that
the two back halves 26, 27 are positively held together, such that
the engagement between the different flanges and recesses is maintained.
Since the back is also locked in its raised position, great stability
is obtained and unintentional lowering of the back will be impossible.
Thus, it is possible to run the wheel-chair by seizing the back
and using it as a handle for manoeuvring the wheel-chair.
The embodiment of the wheel-chair described above is merely given
as an example. Many modifications are possible within the scope
of the invention. Thus, the different parts can be designed otherwise
and be provided with e.g. weight-reducing recesses to further reduce
the weight of the wheel-chair. The material of the load-bearing
parts of the wheel-chair may be e.g. aluminium alloys or magnesium
alloys or other light alloys having the required strength. As back
and seat materials, use can be made of plastics or materials other
than the expanded polyurethane suggested above. |