Patent Publication Number: US-6217050-B1

Title: Adjustable footrest

Description:
TECHNICAL FIELD 
     This invention relates in general to land vehicles and, in particular, to wheelchairs. Most particularly, the invention relates to wheelchair footrests for supporting the feet of a wheelchair occupant. 
     BACKGROUND OF THE INVENTION 
     Wheelchairs are provided with footrests. Footrests typically include a pair of footplates. Each footplate is generally horizontally disposed. Footplates are ordinarily substantially planar in construction. The footplates optionally support toe and ankle straps. The toe and ankle straps are provided for securing the wheelchair occupant&#39;s foot to an upper surface of the footplate. Footplates are generally fastened to the wheelchair side frames with saddle washers and threaded fasteners. Conventional footplates are typically capable of flipping up 90° from their generally horizontal position to a generally vertical position so as to permit ingress and egress of the wheelchair occupant to be accomplished with greater ease. 
     Although displacement of conventional footplates has historically been limited to the 90° displacement described above, more recent innovations in footrests have led to an ability to adjust the inclination or angle of footplates. This adjustment provision permits the ankle of the wheelchair occupant to be adjusted at various angles for the comfort of the wheelchair occupant. 
     Conventional footrests are limited in the ability of the footplates to be adjusted horizontally as well as vertically. Conventional footrests are also limited in that the footrests do not allow the footplates to be independently adjusted to accommodate wheelchair occupants having legs which are of different lengths. What is needed is an adjustable footrest that allows a footplate to be adjusted horizontally as well as vertically to accommodate various wheelchair occupant profiles. Moreover, it is desireable that footplates adjust independently for each leg of the wheelchair occupant. 
     SUMMARY OF THE INVENTION 
     This invention includes an adjustable linkage assembly for supporting the footplate of a wheelchair footrest. The wheelchair footrest has a tube supported by the wheelchair frame. The linkage assembly comprises a plurality of pivots and a plurality of clamps. The clamps are structured and configured to releasably couple the pivots and the footplate together and in substantially fixed positions relative to one another. 
     In another embodiment, the invention includes an extension tube for use with a hanger mounted to a forward portion of a wheelchair. The extension tube adjustably supports a wheelchair footplate. The extension tube is engageable with a hollow portion of the hanger. The extension tube and the hanger are structured and dimensioned to be matingly engageable with one another and to prevent rotation of the extension tube relative to the hanger. 
     Various objects and advantages of this invention will become apparent to those skilled in the art from the following detailed description of the preferred embodiment, when read in light of the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a front perspective view of a motorized wheelchair having a battery mounting system according to the invention. 
     FIG. 2 is an enlarged rear perspective view of the wheelchair and battery mounting system shown in FIG.  1 . 
     FIG. 3 is an enlarged rear-perspective view of the footrest shown in FIG.  1 . 
     FIG. 4 is a side elevational view of the footrest in a first position. 
     FIG. 5 is a side elevational view of the footrest in a second position. 
     FIG. 6 is a side elevational view of the footrest in a third position. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     There is illustrated in FIGS. 1 and 2 a wheelchair  110  comprising a base  112  and a seat frame  114  and backrest  116  supported by the base  112 . The base  112  comprises a pair of side frames  118  and lateral struts or cross tubes  119  and  120  spanning between, and connected to, the side frames  118 . The side frames  118  and the cross tubes  119  and  120  are triangulated to produce a base  112  having suitable structural integrity to support a wheelchair occupant (not shown). A pair of front caster/fork assemblies  136  supports a front portion of the wheelchair  110  on a supporting surface S. As illustrated in FIG. 2, a pair of rear/drive wheels  148  supports a rear portion of the wheelchair  110  on the supporting surface S. 
     As shown in FIG. 1, a pair of footrests  166  each includes a footplate  168  for supporting the feet of the wheelchair occupant. The footrests  166  are supported on a front portion of the wheelchair  110 . An extension tube  170  extends upwardly from the footplate  168 . The extension tube  170  is slidably engageable with a hollow portion of a swing-away hanger  172 . The swing-away hanger  172  is pivotally mounted to a forward portion of the wheelchair  110 . A latch  174  is operatively connected to the swing-away hanger  172 . The latch  174  cooperates with the swing-away hanger  172  to lock the swing-away hanger  172  in a forward position and to release the swing-away hanger  172  to permit the swing-away hanger  172  to be displaced to the sides, or out from in front, of the wheelchair  110 . 
     The present invention includes an adjustable linkage assembly  176 , as shown in FIG. 3, for adjustably supporting the footplate  168  relative to the extension tube  170 . The adjustable linkage assembly  176  comprises a plurality of fulcrum points or pivots  178 ,  180  and  182  and a plurality of clamps  184  and  186  for releasably coupling the pivots  178 ,  180  and  182  and the footplate  168  together and in substantially fixed positions relative to one another. 
     Three pivots  178 ,  180  and  182  are shown, including a first or extension pivot  178 , a second or orbital pivot  180 , and a third or footplate pivot  182 . The extension pivot  178  extends laterally or substantially perpendicularly from the extension tube  170 . The orbital pivot  180  is arranged in close proximity with the extension pivot  178 . The axis “B” of the orbital pivot  180  is substantially parallel to the axis “A” of the extension pivot  178 . The footplate pivot  182  extends substantially co-axially from the orbital pivot  180 . The footplate pivot  182  and the orbital pivot  180  are arranged in tandem to define an adjustable footplate extension cylinder or a tandem pivot assembly  188 . 
     There are illustrated in the drawings two clamps  184  and  186 . These clamps include a first clamp, namely, the bifurcated tandem extension clamp  184 , and a second clamp, namely, the footplate clamp  186 . The tandem extension clamp  184  includes a recess clamp  190  and a threaded clamp  192 . The recess clamp  190  and the threaded clamp  192  may be joined together about the extension pivot  178  and orbital pivot  180  with a socket cap screw  194 . The tandem extension clamp  184  holds the orbital pivot  180  spaced apart relative to the extension pivot  178 . The footplate clamp  186  is structured and dimensioned to clamp the footplate  168  to the footplate pivot  182 . The footplate  168  is releasably attached to the footplate pivot  182  with fasteners, such as the flat head countersunk cap screws  196  and lock nuts  198  shown. Nylon insert lock nuts may be suitable for use in cooperation with the flat head countersunk cap screws  196  to reduce the risk of the flat head countersunk cap screws&#39;  196  coming loose relative to the lock nuts  198 . 
     The extension pivot  178  shown is generally spool-shaped in construction. That is to say, the extension pivot  178  includes a cylindrical annular depression or recess  200  formed between two raised surfaces or shoulders  202 . Likewise, the orbital pivot  180  may be generally spool-shaped in construction wherein the orbital pivot  180  may be provided with an annular recess  204  formed between two shoulders  206 . The shoulders  202  and  206  are preferably provided with chamfered or beveled surfaces  210  to reduce the risk of injury to the wheelchair occupant that may otherwise result if the surfaces  210  were substantially sharp. Moreover, chamfered or beveled surfaces  210  act as guides for directing the tandem clamp  184  into the annular recesses  200  and  204 . 
     The recess clamp  190  and threaded clamp  192  of the tandem extension clamp  184  are elongated in construction. The recess clamp  190  has opposing ends, namely, a first end  212  and a second end  214 . Each end  212  and  214  of the recess clamp  190  has a cylindrical relief  216  and  218 . A substantially oblate or flat surface  230  spans between the two reliefs  216  and  218 . Likewise, the threaded clamp  192  has a first end  222  and a second end  224 , each of which has a cylindrical relief  226  and  228 . A substantially oblate or flattened surface  232  spans between these two reliefs  226  and  228  as well. 
     The recess clamp  190  and the threaded clamp  192  may be coupled together to form the tandem extension clamp  184 . The reliefs  216  and  226  at the first ends  212  and  222  of the recess clamp  190  and the threaded clamp  192 , respectively, cooperatively form a first cylindrical bore or orifice  234  (shown in FIG. 4) which is cooperatively or matingly engageable with the extension pivot  178 . Likewise, the reliefs  218  and  228  at the second ends  214  and  224  of the recess clamp  190  and the threaded clamp  192 , respectively, cooperatively form a second cylindrical bore or orifice  236  (shown in FIG. 4) which is cooperatively or matingly engageable with the orbital pivot  180 . The extension pivot  178  and the orbital pivot  180  are dimensioned and configured to fit tightly within the first and second cylindrical bores  234  and  236  upon applying the tandem extension clamp  184  to the pivots  178  and  180 . 
     For example, the extension pivot  178  may have an outside diameter of about ½ inch and the first cylindrical bore  234  may have an inside diameter of about ½ inch, or even slightly less, so as to fit tightly around the extension pivot  178  upon clamping the tandem extension clamp  184  about the extension pivot  178 . Similarly, the orbital pivot  180  may have an outside diameter of about ⅜ inch and the second cylindrical bore  236  may have an inside diameter of about ⅜ inch, or even slightly less, so as to fit tightly around the orbital pivot  180  upon clamping the tandem extension clamp  184  about the orbital pivot  180 . 
     The recess clamp  190  and the threaded clamp  192  are joined together to form the tandem extension clamp  184  as follows. A hole  238  passes through the recess clamp  190 . A portion of the hole  238  may be dimensioned to permit the socket cap screw  194  to be countersunk. That is to say, the hole  238  may be dimensioned to receive the head of the socket cap screw  194  so that the head of the socket cap screw  194  may be flush with the flat outer surface  240  of the recess clamp  190  when the extension clamp  184  is applied to the extension and orbital pivots  178  and  180 . 
     The threaded clamp  192  has a threaded bore  242 . The threaded bore  242  is threadably engageable with the socket cap screw  194 . The extension clamp  184  is formed by placing the recess clamp  190  and the threaded clamp  192  about the extension and orbital pivots  178  and  180  with the extension and orbital pivots  178  and  180  being received by corresponding first and second cylindrical bores  234  and  236 . The socket cap screw  194  is inserted into and through the hole  238  in the recess clamp  190  and threaded into the threaded bore  242 . The socket cap screw  194  may be tightened until the extension and orbital pivots  178  and  180  are held tightly within the first and second cylindrical bores  234  and  236 , respectively. The socket cap screw  194  is preferably tightened so as to hold the orbital pivot  180  in a fixed position relative to the extension pivot  178  for reasons which will become more apparent in the description that follows. 
     The footplate clamp  186  is a substantially elongated along the axis B as is the footplate pivot  182 . The elongated construction of the footplate clamp  186  and the footplate pivot  182  enables the footplate clamp  186  and the footplate pivot  182  to cooperate to insure that the footplate  168  can support the weight of the wheelchair occupant&#39;s foot and leg (not shown) when encountering forces transverse to the footplate pivot  182  in the direction of the arrow “F”. 
     As is clearly shown, the footplate pivot  182  is merely in the form of an elongated cylindrical shaft extending substantially co-axially from the orbital pivot  180 . It should be noted that the footplate pivot  182  is depressed or recessed relative to the shoulder  206  of the orbital pivot  180  adjacent to the footplate pivot  182 . The shoulder  206  adjacent to the footplate pivot  182  provides an abutment surface  244  for the footplate clamp  186  to abut. 
     The footplate clamp  186  comprises an elongated member  246 . The elongated member  246  defines a cylindrical bore  248  having an axis along the arrow “B” (shown FIG.  3 ). The elongated member  246  is furcated so as to provide a longitudinal break or slit  250  in the elongated member  246  which communicates with the cylindrical bore  248 . An upper substantially planar element  252  extends from the elongated member  246 , substantially tangentially from the cylindrical bore  248 . Extending from the elongated member  246  is a lower substantially planar element  254 . The lower substantially planar element  254  extends substantially radially relative to the cylindrical bore  248 . The upper substantially planar element  252  originates adjacent to an upper boundary of the longitudinal split  250  and the lower substantially planar element  254  originates adjacent to a lower boundary of the longitudinal split  250 . Each substantially planar element  252  and  254  is generally elongated and rectangular in construction. The substantially planar elements  252  and  254  are arranged in a substantially co-planar relationship relative to one another. The elongated member  246  is compressible to the extent that the substantially planar elements  252  and  254  can be moved towards each other, along the lines G—G (shown in FIG.  4 ), resulting in a reduction in the diameter of the cylindrical bore  248 . This permits the elongated member  246  to clamp tightly upon the footplate pivot  182 . 
     The upper substantially planar element  252  is provided with a pair of spaced apart holes  256 . Likewise, the lower substantially planar element  254  is provided with a pair of spaced apart holes  258 . The holes  256  in the upper substantially planar element  252  are arranged to co-align with the holes  258  in the lower substantially planar element  254 . These co-aligning holes  256  and  258  are arranged to co-align with holes  260  in the footplate  168 . The holes  256 ,  258 , and  260  co-align to permit the passage of the flat head countersunk cap screws  196  through the holes  256 ,  258 , and  260 . The holes  260  in the footplate  168  are dimensioned to permit the head of the flat head countersunk cap screw  196  to be substantially flush with the surface of the footplate  168  upon clamping the footplate  168  to the footplate pivot  182 . 
     The footplate  168  is clamped to the footplate pivot  182  as follows. The footplate pivot  182  is inserted into the footplate clamp  186 . The footplate  168  is oriented above the footplate clamp  186  with the holes  256 ,  258 , and  260  in the footplate  168  and the footplate clamp  186  arranged so as to co-align with one another. The flat head countersunk cap screws  196  are passed through the co-aligning holes  256 ,  258 , and  260  in the footplate  168  and the footplate clamp  186 . Lock nuts  198  are arranged below the co-aligning holes  256 ,  258 , and  260 . The flat head countersunk cap screws  196  are threaded into corresponding lock nuts  198 . The flat head countersunk cap screws  196  are tightened into the lock nuts  198  until the footplate clamp  186  clamps tightly about the footplate pivot  182 . The cooperative engagement of the flat head countersunk cap screws  196  and the lock nuts  198  serves two purposes. In addition to clamping the footplate clamp  186  about the footplate pivot  182 , the flat head countersunk cap screws  196  and the lock nuts  198  secure the footplate  168  to the footplate clamp  186 . 
     The operation of the adjustable linkage assembly  176  is illustrated with reference to FIGS. 4 through 6. As shown in FIG. 4, the extension tube  170  slidably engages the swing-away hanger  172 . The elevation of the extension tube  170  is adjustable relative to the swing-away hanger  172  to adjust the height of the footplate  168 . The extension tube  170  is preferably extruded in a shape that is complementary to that of the swing-away hanger  172  so that the extension tube  170  and the swing-away hanger  172  are configured to matingly engage one another. The term “complemetary” here means keyed relative to one another, or having a shape the that closely fits or mates to one another. Although this mating engagement should permit the extension tube  170  to be vertically adjustable relative to the swing-away hanger  172 , the engagement between the extension tube  170  and the swing-away hanger  172  should prevent rotation of the extension tube  170  relative to the swing-away hanger  172  in a direction of the arrow “C”, thereby retaining the footplates  168  in a forwardly disposed position. One manner of resisting rotation between the extension tube  170  and the swing-away hanger  172  is to provide the extension tube  170  with at least one flat side  262  that cooperatively engages a flat side (not shown) within the swing-away hanger  172 , or that is engageable with a fastener, such as a set screw (not shown). Alternatively, the extension tube  170  and the swing-away hanger  172  may be provided with a matingly engageable spline and flute (not shown). These are merely examples of configurations that may be employed to prevent rotation between the extension tube  170  and the swing-away hanger  172 . Although the extension tube  170  is extruded, the extension tube  170  may be formed or fabricated in other manners. 
     The recess clamp  190  and the threaded clamp  192  are joined together about the extension pivot  178  and the orbital pivot  180  to form the tandem extension clamp  184 . The footplate pivot  182  is inserted into the footplate clamp  186  and secured relative to the footplate clamp  186  while fastening the footplate  168  to the footplate clamp  186 . The socket cap screw  194  and flat head countersunk cap screws  196  are tightened so as to retain the pivots  178 ,  180 , and  182  and the footplate  168  in fixed positions. 
     By loosening the flat head countersunk cap screws  196  (shown in FIG. 3) relative to the lock nuts  198  (also shown in FIG.  3 ), the footplate clamp  186  may be freed to pivot about the footplate pivot  182  along the lines H—H, as shown in FIG.  5 . This permits the inclination of the footplate  168  to be adjusted to suit the wheelchair occupant. Moreover, the angle of inclination of the footplate  168  along the lines H—H may be adjusted to accommodate changes in the position of the orbital pivot  180  relative to the extension pivot  178 . 
     As shown in FIG. 6, the position of the orbital pivot  180  may be changed relative to the extension pivot  178 . This is accomplished by loosening the socket cap screw  194  (shown in FIG. 3) sufficiently to permit the extension pivot  178  and the orbital pivot  180  to move relative to the tandem extension clamp  184 , or vice versa. With the socket cap screw  194  loosened, the orbital pivot  180  may be displaced about the extension pivot  178  along the lines J—J. 
     As shown in FIGS. 2 through 4, the adjustable linkage assembly  176  permits the footplate  168  to be adjusted forward and back as well as up and down. This permits the footplate  168  to be positioned to accommodate various wheelchair occupants. For example, wheelchairs may be outfitted with the adjustable linkage assembly  176  during production. When the wheelchair occupant is fitted for the wheelchair, the adjustable linkage assembly  176  may be adjusted to accommodate the profile of the specific wheelchair occupant. Alternatively, the adjustable linkage assembly  176  may be retrofitted to existing wheelchairs as an after-market product. The adjustable linkage assembly  176  is not limited in its application to permit the wheelchairs to be sized to specific wheelchair occupants, but is also suitable for permitting the position of the lower appendages of the wheelchair occupant to be changed. 
     The clamps  184  and  186  shown are merely illustrative of clamps that can be used to carry out the invention. Other clamping arrangements may be suitable for carrying out the invention so long as the clamps may be loosened to permit the pivot linkage assembly  176  to be adjusted or manipulated at the pivots  178 ,  180  and  182 . It should be also understood that other pivots, or that a greater or a lesser number of pivots, may be included so long as the adjustable linkage assembly permits the footplate  168  to be adjusted or manipulated. For example, the adjustable linkage assembly should permit the extensibility and the elevation of the footplate to be adjusted in a forward and rearward direction along the lines K—K (shown in FIG. 6) or upward and downward along the lines L—L (shown in FIG.  6 ). 
     The pivot linkage assembly  176  is preferably fabricated or formed from a substantially rigid or non-elastic material. The pivot linkage assembly  176  should be strong and sturdy. It is preferable that the pivot linkage assembly  176  be made of a metallic material and, most preferably, made of aluminum. 
     In accordance with the provisions of the patent statutes, the principle and mode of operation of this invention have been explained and illustrated in its preferred embodiment. However, it must be understood that this invention may be practiced otherwise than as specifically explained and illustrated without departing from its spirit or scope.