Foldable wheelchair

A foldable wheelchair is provided which includes first and second side frames which each rotatably carry a drive wheel and traveling wheel. A foldable seat extends between the side frames to form a flat, rigid surface when the wheelchair is open and to collapsably pivot upwardly when the wheelchair is folded. First and second hinges are positioned beneath and behind the foldable seat, respectively, and each extends between the side frames so as to pivot about an upwardly extending axis and to move rearwardly as the wheelchair is folded. Both hinges comprise a first arm pivotably secured at one end to a respective one of the side frames and extending generally inwardly and rearwardly of the foldable seat and a second arm pivotably secured at one end to the other of the side frames and at the second end pivotably connected to the other end of the first arm so as to form a hinge therewith.

TECHNICAL FIELD 
The invention relates generally to wheelchairs, and more particularly to 
side-to-side foldable wheelchairs adapted for transportation from one 
location to another for use. 
BACKGROUND ART 
As is known to those familiar with collapsable wheelchair construction, the 
traditional collapsable wheelchair comprises a sling-like seat and back 
extending between the two sides of the wheelchair. The two sides of the 
wheelchair are part of an X frame assembly which performs a scissor-like 
folding movement when the sling seat is pulled upwardly. This type of 
wheelchair possesses positive attributes including the fact that it is 
necessary to raise the seat in order to fold the chair so as to prevent 
accidental folding thereof with the wheelchair occupied. Also, the 
traditional X frame obviates the need for a latching mechanism for the 
frame that would be difficult for a handicapped user of the wheelchair to 
operate. 
Unfortunately, the traditional X frame wheelchair possesses the inherent 
shortcomings of user discomfort and incorrect posture due to lack of 
support by the sling seat and sling back. Therefore, it is generally 
agreed that a rigid-back resilient cushion for both the seat and back are 
to be preferred to the sling seat and sling back configuration for comfort 
and health reasons. Thus, collapsable wheelchairs utilizing X frames have 
been modified in the past by placing a removable rigid-back cushion 
assembly on the seat and/or the back of the wheelchair. This modification 
results in the necessity to remove the rigid-back cusions prior to folding 
the wheelchair. In some circumstances, latches have also been provided to 
secure the rigid-back cushions to the seat and/or back of the wheelchair, 
and these latches have been found difficult to operate by occupants of the 
wheelchair. 
The manner in which the present invention eliminates the disadvantages of 
previously known foldable wheelchairs and advances the state of the art 
will be understood as this specification proceeds. 
DISCLOSURE OF THE INVENTION 
In accordance with the present invention, there is provided a wheelchair 
having a resilient seat cushion supported by a collapsable rigid seat as 
well as a resilient back cushion and back panel which are adapted so that 
the wheelchair can be folded without removing either the seat cushion or 
the back cushion and panel assembly. The wheelchair is further adapted so 
that the seat cushion and the back cushion and panel assembly may both be 
removed, if desired, so that the wheelchair can more easily be placed into 
a car trunk or the like for transportation. Furthermore, the foldable 
wheelchair of the invention obviates the need for a manual latch assembly 
to secure the back cushion and panel thereto since the wheelchair provides 
an automatic latch mechanism which locks the back cushion and panel 
assembly when the wheelchair is opened and unlocks the aforementioned 
assembly when the wheelchair is folded so that it may be easily removed 
therefrom if desired. 
The side-to-side foldable wheelchair of the invention comprises first and 
second side frames each carrying a drive wheel and a traveling wheel. A 
foldable seat extends between the side frames which is adapted to form a 
substantially flat, rigid surface when the wheelchair is open and to 
collapsably pivot upwardly when the wheelchair is folded. A hinge located 
behind the foldable seat extends between the side frames and is adapted to 
pivot about an upwardly extending axis and more rearwardly as the hinge 
moves from a substantially open position when the wheelchair is open to a 
substantially closed position when the wheelchair is folded. 
It is therefore an object of the present invention to provide an improved 
foldable wheelchair. 
It is another object of the present invention to provide an improved 
side-to-side foldable wheelchair which includes a rigid seat and back with 
resilient cushions thereon that may be folded without necessitating the 
removal of the seat or back cushions. 
Still another object of the present invention is to provide an improved 
side-to-side foldable wheelchair which is small and light and easily 
storable in a small car trunk.

BEST MODE FOR CARRYING OUT THE INVENTION 
With reference to FIGS. 1-6 of the drawings, the foldable wheelchair of the 
invention comprises two side frames which are generally designated 10 and 
20. Side frame 10 comprises a vertical tubular members 10A and 10B which 
are connected by horizontal tubular members 10C and 10D to form a rigid 
side frame structure. A swing-away arm is a part of side frame 10 and 
comprises telescopic arm support 10E and arm support 10F which are 
pivotably mounted by suitable conventional means to vertical tubular 
member 10A at one end thereof and secured at the other end thereof to 
vertical arm support 1G. The vertical distance between horizontal arm 
supports 10E and 10F is adjustable to accommodate different size occupants 
of the wheelchair since both vertical arm support 10G and the upper end of 
vertical tubular member 10A to which arm support 10E is attached are 
telescopically adjustable in height within suitable limits of movement. 
The pivotal arm assembly comprising horizontal arm supports 10E, 10F and 
vertical arm support 10G is constructed so as to be upwardly pivotable in 
order to be removed from U-shaped retained 10H and then pivoted laterally 
outwardly in order to facilitate exit from the wheelchair by an occupant 
thereof. It should be appreciated that the actual construction of side 
frame 10 and the swing-away arm assembly thereof is a matter of design 
choice and that, although not shown, an arm support cushion would normally 
be provided on horizontal arm support 10E for the comfort of the user. 
Side frame 20 is constructed similar to side frame 10 and includes vertical 
tubular members 20A and 20B, horizontal tubular members 20C and 20D, 
horizontal arm supports 20E and 20F, vertical arm support 20G and U-shaped 
retainer 20H for the pivotal arm assembly thereof. 
Also, side frame 10 is provided with drive wheel 12 and traveling wheel 14 
rotatably mounted thereto in a conventional manner known to those skilled 
in the wheelchair art, and side frame 20 has corresponding drive wheel 22 
and traveling wheel 24 rotatably mounted thereto. Although not shown in 
the drawings in order to more clearly depict applicant's novel wheelchair 
structure, the wheelchair would most suitably include a foot support or 
rest pivotably mounted to each of traveling wheels 14 and 24 and a manual 
braking mechanism most suitably adapted to be actuated by the user to 
engage drive wheel 12 and drive wheel 22 as necessary to slow the 
wheelchair or to hold it in a stationary position. 
With particular reference now to FIGS. 4 and 5, it can be seen that side 
frames 10 and 20 are connected by a first hinge, generally designated 30, 
a second hinge generally designated 40, and a collapsable seat generally 
designated 50. First hinge 30 is positioned beneath collapsable seat 50 
and comprises two relatively pivotably movable hinge arms 30A and 30B. 
Hinge arm 30A is pivotably mounted to vertical tubular member 10B of side 
frame 10 at one end and to hinge arm 30B at the other end. Hinge arm 30B 
forms a pivotable hinge at one end with hinge arm 30A and is pivotably 
mounted to vertical tubular member 20B of side frame 20 at the other end. 
Second, hinge 40 is constructed of two pivotably movable arms 40A and 40B. 
Hinge 40A is pivotably mounted to vertical tubular member 10A of side 
frame 10 at one end and forms a pivotably movable hinge at the other end 
with hinge arm 40B. Hinge arm 40B is pivotably mounted at one end to hinge 
arm 40A and at the other end to vertical tubular member 20A of side frame 
20. Thus, first hinge 30 and second hinge 40 are each positioned with a 
generally upwardly extending hinge pivoting axis and each hinge travels 
from a forward position when the wheelchair is open to a rearward position 
when the wheelchair is folded. First and second hinges 30 and 40, 
respectively, are each designed so that when the wheelchair is unfolded 
the hinge pivot axis lies in a plane behind the plane defined by the two 
pivot points of the hinge arms with the frame so that the hinge is never 
in a dead center position and thus will readily begin closing and moving 
rearwardly when side frames 10 and 20 of the wheelchair are urged 
inwardly. Most suitably, nylon bushings are provided at each of the three 
pivot points of first hinge 30 and second hinge 40. 
Collapsable seat 50, as best seen in FIGS. 2-5, comprises two levers 50A 
and 50B which are each pivotably mounted to horizontal tubular member 20D 
of side frame 20 at one end and at the other end are pivotably joined with 
a second pair of pivotable levers 50C and 50D which are each mounted at 
their other end to horizontal tubular member 10D of side frame 10. Thus, 
pivotable levers 50A-50D form the frame of a rigid, flat seat when the 
wheelchair is open and will pivotably move upwardly when the wheelchair is 
folded (see FIGS. 2 and 5). Pivotable levers 50A, 50B have a first rigid 
seat portion A therebetween and pivotable levers 50C, 50D have a second 
rigid seat portion B therebetween, and pivotable levers 50A, 50B are each 
provided with an overlapping tab 50A', 50B' (see FIGS. 2 and 5) which 
serve as stops against the top of second seat portion B so as to render 
collapsable seat 50 flat and rigid when the wheelchair is open. As seen in 
FIGS. 1 and 4, a cushion 52 is placed on collapsable seat 50 for the 
comfort of the user. 
Seat cushion 52 is removably secured to first rigid seat portion A by an 
elastic harness (see FIG. 2) comprising a flexible sheet material 53 and 
VELCRO strip 54 secured at one side of seat portion A with elastic strips 
56A and 56B extending therefrom to the other side of seat portion A. The 
underside of cushion 52 is provided with a mating VELCRO strip (not shown) 
to removably engage VELCRO strip 54 of the harness assembly and thus be 
secured to collapsable seat 50 for the comfort of the user of the 
wheelchair. When the wheelchair is folded, cushion 52 will remain secured 
to the harness assembly of seat portion A and thus pivot upwardly 
therewith. A cushion shield 58 (see FIG. 1) is provided on side frame 20 
to maintain cushion 52 in place as the wheelchair is folded and seat 
portion A of collapsable seat 50 pivots upwardly. The elastic harness 
assembly mentioned heretofore provides for a slight amount of vertical 
movement of cushion 52 as it is snubbingly engaged between shield 58 and 
upwardly pivoted seat portion A of collapsable seat 50. Also, the 
pivotable mounting locations of levers 50A and 50B to tubular member 20D 
of side frame 20 are spaced inwardly (see FIGS. 2 and 5) to allow room 
between seat portion A and cushion shield 58 for cushion 52 when the 
wheelchair is folded. 
Finally, the wheelchair of the present invention includes a removable back 
assembly comprising a rigid back panel 60 (see FIG. 2) and a resilient 
back cushion 62 which are pivotably mounted to upright handle 64 which is 
removably received by second hinge 40. Thus, a removable back assembly 
with a cushion thereon is provided which is adapted to pivot when in use 
about a horizontal axis where back panel 60 is pivotably mounted to 
upright handle 64, and the entire back assembly is adapted to pivot 
towards the longitudinal direction of the wheelchair and to be removable 
for easy storing when the wheelchair is folded, as will be explained in 
detail below. 
Back panel 60, back cushion 62 and handle 64 of the removable back assembly 
of the wheelchair can best be seen now with reference to FIGS. 1-2, 4 and 
6. With particular reference to FIG. 6, the locking feature of the 
wheelchair can be fully appreciated. As described heretofore, the 
removable back assembly of the wheelchair of the present invention does 
not require manual latching as do many rigid-back supports previously 
provided as add-on or removable back supports for conventional 
wheelchairs. The wheelchair of the present invention includes an automatic 
locking mechanism which serves to lock the removable back assembly to the 
wheelchair when the wheelchair is open and to unlock as well as pivot the 
back assembly towards the longitudinal direction of the wheelchair when 
the wheelchair is folded. This assures that the back assembly, including 
the wheelchair handle, cannot be accidentally removed while the wheelchair 
is open and occupied. The removable back assembly is adapted to pivot when 
the wheelchair is folded in order to facilitate folding the wheelchair 
into a relatively narrow width. 
Both the locking and pivoting of the removable back assembly can be better 
explained with specific reference to FIG. 6 of the drawings illustrating 
hinge 40 when the wheelchair is folded. As seen therein, upright handle 64 
is provided with a projection or lock pin 64A extending outwardly from the 
base thereof. Hinge 40, which is constructed so as to removably receive 
upright handle 64, comprises hinge arm 40A which terminates in a vertical 
tube which serves as the inside tube of second hinge 40 and hinge arm 40B 
which also terminates in a vertical tube which is pivotably mounted over 
the vertical tube of hinge arm 40A in order to form second hinge 40. The 
vertical tube of hinge arm 40B defines a vertical open-ended slot 40B' at 
the top thereof which is located so as to register with the upwardly 
extending portion of an open-ended and reverse L-shaped slot 40A' in the 
vertical tube of hinge arm 40A. When the two slots are superimposed as 
shown in FIG. 6, upright handle 64 may be slidably inserted into hinge 40 
with lock pin 64A being received and traveling down the length of the two 
superimposed slots. In this position of hinge 40 corresponding to the 
wheelchair being folded, upright handle 64 of the back assembly may be 
either slidably inserted or slidably removed from second hinge 40 of the 
folded wheelchair. When upright handle 64 is initially inserted into 
second hinge 40, the back panel 60 and cushion 62 will be pivoted 
generally toward the lengthwise direction of the wheelchair. The 
wheelchair may then be opened which will force hinge arms 40A and 40B 
outwardly in the direction of the arrows of FIG. 6 which serves to rotate 
inner tube 40A and slot 40A' counterclockwise and outer tube 40B and slot 
40B' clockwise and thus to (1) capture lock pin 64A in the laterally 
extending or leg portion of the reverse L-shaped slot of tube 40A and (2) 
to pivot handle 64 clockwise so that the back assembly extends 
transversely to the open wheelchair. Thus, the entire back assembly is 
locked into place extending transversely to the lengthwise direction of 
the wheelchair when the wheelchair is open and cannot be accidentally 
removed. Also, and very advantageously, the locking mechanism provided by 
second hinge 40 functions automatically and does not require any manual 
locking and unlocking of the back assembly which would present some 
inconvenience as well as risk of injury to the user of the wheelchair. 
In operation, the wheelchair after use may be folded by merely pulling 
upwardly on a handle secured to collapsable seat 50. Collapsable seat 50 
will pivot upwardly and first and second hinges 30 and 40, respectively, 
will travel rearwardly and close so as to accommodate the lateral 
collapsing of the wheelchair into a narrow configuration. Hinge 40 will 
also serve to unlock and pivot the back assembly generally towards the 
lengthwise direction of the wheelchair. As a matter of choice, seat 
cushion 52 and the removable back assembly may be left in place and the 
wheelchair stored and transported to a new location. If it is desired to 
place the folded wheelchair into a small compartment such as the trunk of 
a small car, seat cushion 52 and the back assembly may be removed in order 
that the height and width of the wheelchair as well as the weight thereof 
will be even further reduced. 
It is contemplated that the preferred embodiment of the wheelchair will be 
constructed of 1 1/8 inch aluminum tubing with selected wall thicknesses 
varying between 0.108 and 0.083 inches and that the total weight of the 
wheelchair will be about 32 pounds. Thus, the novel wheelchair of the 
present invention is lighter than many conventional X frame wheelchairs 
known heretofore so as to further facilitate its ease of use. Also, 
although the preferred embodiment of the wheelchair has been described 
with both first and second hinges 30 and 40, respectively, applicant 
further contemplates that the wheelchair of the invention could be 
constructed with only second hinge 40 and function satisfactorily. 
Thus, it will be understood that various details of the invention may be 
changed without departing from the scope of the invention. Furthermore, 
the foregoing description is for the purpose of illustration only, and not 
for the purpose of limitation--the invention being defined by the claims.