Patent Publication Number: US-7896385-B2

Title: Foldable wheelchair

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Patent Application No. 60/974,214 filed Sep. 21, 2007, the entire contents of which are incorporated herein by reference and should be considered a part of this specification. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to a wheelchair, and more particularly to a foldable wheelchair. 
     2. Description of the Related Art 
     Foldable wheelchairs are well known in the art. Generally, foldable wheelchairs are folded along a longitudinal axis of the wheelchair, via a scissors-type hinge between the wheels, so as to bring together the sides of the chair (i.e., the wheels are moved inward toward the longitudinal axis). The wheels may or may not be removable. With a canvas seat and a canvas back, such chairs may be readily and quickly folded and unfolded, though the seat material is often not particularly comfortable. 
     However, such foldable wheelchairs suffer from the disadvantage of bulk and weight. Folding such a chair reduces the width of the chair transverse to its longitudinal axis, but the dimensions of the height and depth of the chair remain the same. Accordingly, such a chair, even in the folded configuration, still has considerable bulk with regard to the overall volume that the chair might occupy in a place of storage (e.g., the trunk of a vehicle). Such bulk makes it difficult for a user to easily disassemble the chair and store it in a compact storage space, such as the trunk of a car, and reduces the storage space available to store other articles. Additionally, such foldable wheelchairs can be very heavy, making them more difficult for a user to lift. 
     Accordingly, there is a need for a compact foldable wheelchair that can be easily folded and unfolded by a user, is lightweight and has high structural strength. 
     SUMMARY OF THE INVENTION 
     In accordance with one embodiment, a foldable wheelchair is provided. The wheelchair comprises a seat bottom configured to support a user thereon. The wheelchair also comprises a seat back movably coupled to the seat bottom. The seat back is movable about an axis generally transverse to a longitudinal axis of the wheelchair between a folded position such that the seat back extends generally parallel to a plane defined by the seat bottom and one or more unfolded position so as to provide back support to the user. The wheelchair further comprises a leg support pivotably coupled to the seat bottom. The leg support is movable about a second axis generally transverse to the longitudinal axis of the wheelchair between a folded position such that the leg support extends generally parallel to said plane defined by the seat bottom and an unfolded position configured to provide support to the user&#39;s legs during use of the wheelchair. In the folded position the seat bottom, seat back and leg support extend along generally parallel planes. 
     In accordance with another embodiment, a foldable wheelchair is provided comprising a seat bottom frame defining a plane and configured to support a user thereon. The wheelchair also comprises a seat back frame pivotably coupled to the seat bottom about an axis generally transverse to a longitudinal axis of the wheelchair. The seat back frame is pivotable between a folded position such that the seat back extends generally parallel to a plane defined by the seat bottom and one or more unfolded position so as to provide back support to the user. The wheelchair further comprises a leg support pivotably coupled to the seat bottom about an axis generally transverse to a longitudinal axis of the wheelchair, the leg support frame movable between a folded position such that the leg support frame extends generally parallel to said plane defined by the seat bottom frame and an unfolded position configured to provide support to the user&#39;s legs during use of the wheelchair. Additionally, wheelchair comprises means for releasably locking the leg support frame in the unfolded position relative to the seat bottom frame, wherein in the folded position the seat bottom frame, seat back frame and leg support frame extend along generally parallel planes. 
     In accordance with still another embodiment, a method for operating a foldable wheelchair is provided. The method comprises moving a seat back pivotably coupled to a seat bottom about an axis generally transverse to a longitudinal axis of the wheelchair from an unfolded position to a folded position so that a plane defined by the seat back is generally parallel to a plane defined by a seat bottom. The method also comprises moving a leg support pivotably coupled to the seat bottom about an axis generally transverse to the longitudinal axis of the wheelchair from an unfolded position to a folded position so that a plane defined by the leg support is generally parallel to a plane defined by a seat bottom. Additionally, the method comprises moving one or more rear wheel supports releasably coupled to the seat bottom from a deployed position where a plane defined by the rear wheel support is generally non-parallel to the plane defined by the seat bottom to a folded position where the plane defined by the rear wheel support is generally parallel to the plane defined by the seat bottom. In the folded position the seat bottom, seat back and leg support extend along generally parallel planes. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and other features, aspects and advantages of the present inventions will now be described in connection with preferred embodiments, in reference to the accompanying drawings. The illustrated embodiments, however, are merely examples and are not intended to limit the inventions. The drawings include the following 11 figures. 
         FIG. 1  is a schematic profile view of a wheelchair frame in a folded configuration, in accordance with one embodiment. 
         FIG. 2  is a schematic profile view of the wheelchair frame of  FIG. 1  showing one step in the deployment of a leg support portion of the frame into a fully deployed configuration. 
         FIG. 3  is a schematic profile view of the wheelchair frame of  FIG. 1  showing another step in the deployment of the leg support portion of frame into a fully deployed configuration. 
         FIG. 4  is a schematic profile view of the wheelchair frame of  FIG. 1  showing the leg support portion of the frame in a fully deployed configuration. 
         FIG. 5  is a schematic sectional view of the wheelchair frame of  FIG. 1  showing a wheel support portion in a folded configuration, in accordance with one embodiment. 
         FIG. 6  is a schematic sectional view of the wheelchair frame of  FIG. 1  showing one step in the deployment of the wheel support portion of  FIG. 5  into a fully deployed configuration. 
         FIG. 7  is a schematic sectional view of the wheelchair frame of  FIG. 1  showing the wheel support portion of  FIG. 5  in a fully deployed configuration. 
         FIG. 8  is a schematic profile view of the wheelchair frame of  FIG. 1  with the leg support and wheel support portions in a fully deployed configuration. 
         FIG. 9  is a schematic sectional view of the wheelchair frame of  FIG. 8  with the back support portion in a fully deployed configuration, in accordance with one embodiment. 
         FIG. 10  is a schematic profile view of the wheelchair frame of  FIG. 1  in a fully deployed configuration and assembled with rear and front wheels. 
         FIG. 11  is a schematic sectional view of another embodiment of a back support locking mechanism for a wheelchair frame. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     In the following detailed description, terms of orientation such as “top,” “bottom,” “upper,” “lower,” “front,” “rear,” and “end” are used herein to simplify the description of the context of the illustrated embodiments, and are viewed from the vantage point of a user seated on the wheelchair. Likewise, terms of sequence, such as “first” and “second,” are used to simplify the description of the illustrated embodiments. Because other orientations and sequences are possible, however, the present invention should not be limited to the illustrated orientation. Those skilled in the art will appreciate that other orientations of the various components described above are possible. 
       FIG. 1  illustrates one embodiment of a foldable wheelchair in a folded configuration. The wheelchair includes a frame  100  having a seat bottom portion  10 , a seat back portion  30  and a leg support frame  50 . A support strap  60  can extend across the leg support frame  50  for additional support of the legs of a user. Additionally, the leg support frame  50  can include a cross-member  52  that can support a user&#39;s feet thereon during use. The wheelchair frame  100  also includes a rear wheel axle support  70  for attaching rear wheels to the wheelchair frame  100 . 
     Additionally, the wheelchair frame  100  includes front wheel mounts  80  coupled to the leg support frame  50 . In the illustrated embodiment, the front wheel mounts  80  are bolted to the leg support frame  50 . In another embodiment, the front wheel mounts  80  can be welded to the leg support frame  50 . In still another embodiment, the front wheel mounts  80  can be movably coupled (e.g., via clamps) to the leg support frame  50 , for example, to accommodate front wheels of different sizes. In the illustrated embodiment, the front wheel mounts  80  can include sockets  82  that lockingly receive castor wheels  120  (see  FIG. 10 ) therein. The sockets  82  can be angled relative to the leg support frame  50  in such a manner that an axis of the sockets  82  is generally vertical when the wheelchair frame  100  is in the unfolded configuration (see  FIG. 10 ). 
     As shown in  FIG. 1 , following removal of the wheels from the wheelchair, the wheelchair frame  100  can be folded into a substantially compact configuration where the seat back portion  30 , leg support frame  50  and rear wheel axle support  70  are moved into a position generally parallel to a plane defined by the seat bottom portion  10 . In the folded configuration, as shown in  FIG. 1 , the wheelchair frame  100  advantageously has a height H of less than about six inches, more preferably less than about 5.5 inches, and most preferably about five inches. Accordingly, the wheelchair frame  100  achieves a substantially compact configuration in the folded state, facilitating lifting and storing of the wheelchair in a compact storage space (e.g., a car trunk, car rear seat, or a suitcase), as well as traveling (e.g., on a plane, car, train or ship) with the wheelchair. 
     With continued reference to  FIG. 1 , the leg support frame  50  is pivotally coupled to the seat bottom portion  10  via one or more pivot joint. In the illustrated embodiment, three pivot joints couple the leg support frame  50  to the seat bottom portion  10 . Two of the pivot joints  54  couple lateral elongate members  56  of the leg support frame  50  to corresponding lateral elongate members  12  of the seat bottom portion  10 . The lateral elongate members  56  of the leg support frame  50  preferably have a curved portion  58  proximate the pivot joint  54  and a generally straight portion  60 . 
     A third pivot joint  62  couples an elongate support member  14  coupled to the seat bottom portion  10  and a fork member  64  coupled to the lateral elongate members  56  of the leg support frame  50 . Preferably, the two pivot joints  54  between the lateral elongate members  12 ,  56  of the seat bottom portion  10  and leg support frame  50  are generally aligned with the pivot joint  62  between the elongate support member  14  and the fork member  64 . In the illustrated embodiment, the third pivot joint  62  between the elongate support member  14  and fork member  64  is disposed rearwardly of the two pivot joints  54  between the lateral elongate members  12 ,  56  of the seat bottom portion  10  and leg support frame  50 . 
     Preferably, the elongate support member  14  extends generally along a longitudinal axis of the wheelchair. As shown in  FIGS. 2-4 , the elongate support member  14  couples to, and extends between walls  16 a,  16 b of, a channel  16  of the seat bottom portion  10  that extends generally along the longitudinal axis of the wheelchair frame  100  transverse to cross-members  18  of the seat bottom portion  10 . While in the folded configuration, the elongate support member  14  preferably extends into the channel  16  (see  FIG. 2 ), thereby providing a more compact configuration. 
     In the illustrated embodiment, the pivot joints  54 ,  62  can include a protruding member  66  formed on one support member  12  coupled within a channel  68  formed in the corresponding support member  56 . However, the pivot joints  54 ,  62  can have other suitable configurations. 
       FIGS. 2-4  show the wheelchair frame  100  being moved into an unfolded configuration. To unfold the wheelchair frame  100 , the leg support frame  50  is rotated outward from the folded position (see  FIG. 1 ), so that the lateral elongate members  56  of the leg support frame  50  and the lateral elongate members  12  of the seat bottom portion  10  are aligned with each other proximal the pivot joints  54 . As the leg support frame  50  is unfolded, the elongate support member  14  also becomes aligned with the fork member  64 . Advantageously, the alignment of the elongate support member  14  and fork member  64  inhibits the further outward rotation of the leg support frame  50 . 
     With continued reference to  FIGS. 3 and 4 , the wheelchair frame  100  can have a locking mechanism  68  for substantially locking the leg support frame  50  in the fully unfolded configuration. In one embodiment, the locking mechanism  68  can include a sleeve  68 a movable (e.g., slidable) over the elongate support member  14  and over the pivot joint  62  that joins it to the fork member  64  of the leg support frame  50  while the leg support frame  50  is in the unfolded position. Advantageously, the sleeve  68 a, which has a simple construction, is easily actuatable to lock and unlock the leg support frame  50  in the unfolded position and facilitates the folding and unfolding of said frame  50 . Additionally, the sleeve  68 a advantageously fixes the leg support frame  50  in the unfolded position relative to the seat bottom portion  10  and substantially inhibits the leg support frame  50  from rotating relative to the seat bottom portion  10 . Moreover, the sleeve  68 a, the elongate support member  14  and the fork member  64  provide a substantially stiff wheelchair frame  100  in the unfolded position. In one embodiment, the sleeve  68 a can be spring-loaded so as to be biased toward the leg support frame  50 , the sleeve  68 a slidable rearward to expose the pivot joint  62  and allow the folding of the leg support frame  50 . 
     Though the locking mechanism  68  includes a sleeve in the illustrated configuration, the locking mechanism  68  can have any suitable configuration. In one embodiment, sleeves may optionally be included on the lateral elongate members  12  of the seat bottom, said sleeves movable over the pivot joints  54  between the lateral elongate members  12  of the seat bottom portion  10  and the lateral elongate members  56  of the leg support frame  50 . In another embodiment (not shown), the locking mechanism can include a pin insertable through holes in the elongate support and fork members  14 ,  64 , said holes aligning when the leg support frame  50  is in the unfolded position. 
       FIGS. 5-7  show the deployment of the rear wheel axle support  70  from the folded configuration into the deployed configuration. In the illustrated embodiment, the rear wheel axle support  70  includes an axle shaft  72  that extends between axle mounts  74  movably mounted to the lateral elongate members  12  of the seat bottom portion  10 . In the illustrated embodiments, the axle mounts  74  are clamps, where each clamp clamps about one of the lateral elongate members  12  via bolts  74   a . The axle mounts  74  can advantageously be moved along the lateral elongate members  12  and mounted at a desired location, so as to vary the balance of the wheelchair, as further discussed below. 
     As shown in  FIGS. 5-7 , the rear wheel axle support  70  also includes wheel mounts  76  rotatably coupled to the axle shaft  72 , wherein the wheel mounts  76  can be mounted to the axle mounts  74  in one or more angular position. Each wheel mount  76  preferably includes a hub  78  that extends generally transverse to the longitudinal axis of the wheelchair. The hub  78  preferably receives a wheel connector, such as a bolt, therethrough to which a rear wheel  140  (see  FIG. 10 ) can be coupled. The wheel mounts  76  can include one or more stud or peg  76   a  that can be inserted into one or more bore  74   a  formed on the axle mount  74  to substantially fix the position of the wheel mount  76  relative to the axle mount  74 . In the illustrated embodiment, the wheel mounts  76  each have a plurality of studs  76 a, and the axle mounts  74  each have the same, or a larger, number of bores  74   a.    
     The wheel mounts  76  are preferably coupled to the axle mounts  74  via the studs  76   a  and bores  74   a , so that the hubs  78  of the wheel mounts  76  extend at a desired angular position relative to the lateral elongate members  12 . In one embodiment, the wheel mounts  76  can be mounted to the axle mounts  74  so as to extend along a plane generally normal to the lateral elongate members  12 . In another embodiment, the wheel mounts  76  can be mounted to the axle mounts  74  so that the hubs  78  of the wheel mounts  76  are positioned forwardly of the axle shaft  72 . In still another embodiment, the wheel mounts  76  can be mounted to the axle mounts  74  so that the wheel mounts  76  are positioned rearwardly of the axle shaft  72 . Advantageously, said angular positioning of the wheel mounts  76  also allows the wheelchair balance to be varied, and can also be used to accommodate rear wheels  140  of different sizes. 
     Once the wheel mounts  76  are coupled to the axle mounts  74  in the desired position, an axle locking mechanism  79  can be actuated to substantially lock the wheel mounts  76  in the desired position. In the illustrated embodiment, the axle locking mechanism  79  includes locking pins  79   a  insertable through corresponding holes  72   a  in the axle shaft  72 . However, the axle locking mechanism  79  can have other suitable configurations. For example, the axle locking mechanism  79  can include nuts (not shown) theradably movable along the axle shaft  72  to engage and substantially hold the wheel mounts  76  in coupling engagement with the axle mounts  74 . 
     As discussed above, the location of the axle mounts  74 , as well as the angular positioning of the wheel mounts  76 , can be used to vary the balance of the wheelchair. For example, the axle mounts  74  can be positioned, and/or the wheel mounts  76  oriented, so that the hubs  78  are positioned forwardly of a plane generally normal to the lateral elongate members  12  of the seat bottom portion  10  at the pivot junction  20  with the seat back portion  30 . Such a configuration increases the ease with which a user can tilt the wheelchair to raise the front wheels  120  thereof off the ground during use. Similarly, the axle mounts  74  can be positioned, and/or the wheel mounts  76  oriented, so that the hubs  78  are positioned rearwardly of said plane generally normal to the lateral elongate members  12  of the seat bottom portion  10 , in order to reduce the ease with which the front wheels  120  of the wheelchair can be tilted off the ground, thereby providing a wheelchair with increased balance during use. 
       FIG. 8  shows the wheelchair frame  100  in the unfolded position, except for the unfolding of the seat back portion  30 . As shown in the illustrated embodiment, the wheel mounts  76  are positioned below the axis of the axle shaft  72 . Additionally, in the illustrated embodiment, the lateral elongate members  56  of the leg support frame  50  extend at an angle relative to the seat bottom portion  10  when in the unfolded position. 
       FIGS. 8 and 9  show the deployment of the seat back portion  30  from the folded position ( FIG. 8 ) to the unfolded position ( FIG. 9 ). In the illustrated embodiment, the seat back portion  30  couples to the seat bottom portion  10  via pivot connections  20  coupled to the lateral ends  22   a  of a rear cross-member  22  (see  FIG. 8 ) of the seat bottom portion  10 . The pivot connection  20  can include a connector  20   a , such as a bolt, that couples lateral elongate members  32  of the seat back  30  to corresponding extension members  22   b  coupled to and extending generally normal to the lateral elongate members  12  of the seat bottom portion  10 . A seat back locking mechanism  34  can be used to lock the position of the seat back portion  30  relative to the seat bottom portion  10 , for example, in the unfolded position. In the illustrated embodiment, the seat back locking mechanism  34  includes one or more sleeve  34   a  movable over the lateral elongate member  32  and corresponding extension member  22   b . In another embodiment, the seat back locking mechanism  34  can include two sleeves  34   a , each movably coupled to a lateral elongate member  32  thereof and movable over the corresponding lateral elongate member  32  and extension member  22   b  to substantially lock both sides of the seat back  30  relative to the seat bottom portion  10 . However, the seat back locking mechanism  34  can have other suitable configurations. For example, in one embodiment, locking pins can be inserted through holes in the lateral elongate members  32  of the seat back  30  and extension member  22   b , said holes alignable when the seat back  30  is in the desired deployed orientation relative to the seat bottom portion  10 . 
       FIG. 10  shows a fully assembled wheelchair  200  having the wheelchair frame  100  in the fully deployed configuration and front and rear wheels  120 ,  140  attached thereto. 
       FIG. 11  shows another embodiment of a pivot connection  20 ′ between the lateral sides  32  of the seat back portion  30  and the seat bottom portion  10 . In the illustrated embodiment, the pivot connection  20 ′ includes a threaded end  20   a ′ that can be threadably coupled to a corresponding thread formed in open ends (not shown) of the lateral elongate members  12  of the seat bottom portion  10 . The pivot connection  20 ′ can be coupled to the lateral elongate members  32  of the seat back  30  via a bolt  20   b ′ extending through a center bore of the pivot joint  20 ′. The pivot joint  20 ′ can also have a plurality of holes  20   c ′ formed circumferentially about said center bore. A corresponding hole  32   a  can be formed on the lateral elongate members  32  of the seat back  30 , said hole  32   a  being in alignment with said plurality of holes  20   c ′ as the seat back  30  is pivoted relative to the seat bottom  10 . The seat back  30  can be fixed relative to the pivot joint  20 ′ by, for example, inserting a bolt, screw or pin, though the aligned holes  20   c ′,  32   a  in the pivot joint  20 ′ and the lateral elongate members  32  of the seat back  30 . However, the pivot joint  20 ′ can have other configurations. In one embodiment (not shown), the pivot joint can be a ratchet and pawl system, wherein the seat back  30  can be rotated outward from the folded position to a desired deployed position, the pawl locking said position against the ratchet. In such an embodiment, a release mechanism can be employed to release the pawl from engagement with the ratchet. 
     To move the wheelchair frame  100  into the folded configuration, the rear wheels  140  and front wheels  120  are removed. The seat back locking mechanism  34  is disengaged and the seat back  30  is moved into a folded position generally parallel to the seat bottom portion  10  (see  FIG. 8 ). Also, the axle locking mechanism  79  is released and the wheel mounts  76  moved axially along the axle shaft  72  and away from the axle mounts  74  to disengage the axle mounts  74 . The wheel mounts  76  are then moved toward the seat bottom portion  10  so as to extend along a plane generally parallel to the seat bottom portion  10 . The leg support locking mechanism  68  is disengaged, for example, by moving the sleeve  68   a  to expose the pivot joint  62  between the elongate support member  14  and the fork member  64 , and the leg support frame  50  is moved toward the seat bottom portion  10  so that it extends generally parallel to the seat bottom portion  10 . The wheelchair frame  100  can then be easily lifted and stored in a compact storage space. 
     In a preferred embodiment, the wheelchair frame  100  can be made of aluminum, which provides for a lightweight, yet stiff frame. However, the wheelchair frame  100  can be made of any suitable material, such as other metals (e.g., titanium). 
     The wheelchair frame  100  can also include other components known in the art. For example, foldable foot rests (not shown) can be coupled to the leg support frame  50  and oriented to be foldable in a plane generally parallel to the seat bottom portion  10  when the wheelchair frame  100  is moved into the folded configuration. 
     Although these inventions have been disclosed in the context of a certain preferred embodiments and examples, it will be understood by those skilled in the art that the present inventions extend beyond the specifically disclosed embodiments to other alternative embodiments and/or uses of the inventions and obvious modifications and equivalents thereof. For example, though certain materials have been identified in the preferred embodiments disclosed above, one of ordinary skill in the art will recognize that other suitable materials can also be used. In addition, while a number of variations of the inventions have been shown and described in detail, other modifications, which are within the scope of the inventions, will be readily apparent to those of skill in the art based upon this disclosure. It is also contemplated that various combinations or subcombinations of the specific features and aspects of the embodiments may be made and still fall within one or more of the inventions. Accordingly, it should be understood that various features and aspects of the disclosed embodiments can be combine with or substituted for one another in order to form varying modes of the disclosed inventions. Thus, it is intended that the scope of the present inventions herein disclosed should not be limited by the particular disclosed embodiments described above.