Abstract:
A tether system for the removable leg supports of a wheelchair to prevent the misplacement of the leg supports when they are removed to facilitate the loading or unloading of a patient from the wheelchair. The leg supports are tethered with a pair of cord rewind assemblies fixed to the inside frame of the wheelchair to conserve space. These rewind mechanisms permit the nurse to remove the leg supports from the wheelchair, extend the respective cords from the rewind assemblies to a desired temporary storage location, and automatically lock the cord and the leg supports in that extended position until the cord is pulled slightly releasing the lock and permitting the cords to be rewound or retracted when the nurse remounts the leg supports on the wheelchair frame assembly.

Description:
BACKGROUND OF THE INVENTION 
     The loss or misplacement of the leg supports on wheelchairs has become a major problem in the institutional health care industry. In this environment, there may be dozens of wheelchairs in a small area, such as a rehabilitation area, or an open residential area, or even a dining area. 
     When transferring a patient from a wheelchair to another location such as a bed, chair, van or toilet, it is usually more convenient and sometimes necessary to remove the leg supports from interfering with patient movement or preventing the wheelchair from moving closely to an obstruction. This problem is present even in wheelchairs with swing out leg supports, such as manufactured by Invacare 1  Corporation. 1. Invacar® is a registered trademark of Invacare Corporation of Elyria, Ohio. 
     As a practical matter, these crowded wheelchair areas result in the confusion of which leg supports go with which wheelchair because they are different from one wheelchair to another. 
     There have been prior attempts to solve these problems including providing brackets on the wheelchair frame as exemplified in U.S. Pat. No. 7,487,989 to Crosby, II issued on Feb. 10, 2009. This solution makes the problem worse by enlarging the envelope of the wheelchair. 
     Another attempt provides covers for the leg supports wherein the covers are locked to the wheelchair arms after removal. This system for a Footrest and Legrest Assembly Storage Bag for Wheelchair is manufactured by Amerisoft Medical at amerisoftmedical.com. 
     Another system is shown in the Google download of MedicalProductsDirect.com. for “Wheelchair Footstraps and Foot-Pad Accessories”. 
     SUMMARY OF THE PRESENT INVENTION 
     In accordance with the present invention, a wheelchair footrest tether assembly is provided for the removable leg supports of a wheelchair to prevent the misplacement of the leg supports when they are removed to facilitate the loading or unloading of a patient from the wheelchair. The leg supports are tethered with a pair of cord rewind assemblies fixed to the inside frame of the wheelchair to conserve space. These rewind mechanisms permit the nurse to remove the leg supports from the wheelchair, extend the respective cords from the rewind assemblies to a desired temporary storage location, and automatically lock the cord and the leg supports in that extended position until the cord is pulled slightly releasing the lock and permitting the cords to be rewound or retracted when the nurse remounts the leg supports on the wheelchair frame assembly. 
     The cord rewind assemblies operate in a similar manner to the auto-release-lock electric cord rewind assemblies found today on vacuum cleaners such as Hoover and Eureka. 
     Other objects and advantages of the present invention will appear more clearly from the following detailed description. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of the present wheelchair assembly with removable and tethered leg rest assemblies; 
         FIG. 2  is an exploded sub-assembly of one side frame assembly with a rewind mechanism according to the present invention fixed to the inside frame and tethered to the leg rest assembly; 
         FIG. 3  is a perspective view of the present wheelchair assembly similar to  FIG. 1  with the leg rest removed from the wheelchair and placed on the floor while remaining tethered to the respective rewind assemblies, and; 
         FIG. 4  is a perspective view of one of the rewind assemblies according to the present invention with its cover plate removed. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     According to the drawings and particularly  FIG. 1 , the present wheelchair assembly includes side frames A, leg support assemblies C, a seat assembly E, arm rest assemblies F, a curved step mounting assembly G, and a pair of rewind assemblies  300  and  301  attached inside the side frame assemblies F, each tethered to the foot rest assemblies C 2  and C 1  respectively, so that when the foot rest assemblies C 1  and C 2  are removed from the wheelchair assembly, the tethers  304  and  305  attached to the footrest assemblies by brackets  306  and  307 , prevent the leg and foot rest assemblies C 1  and C 2  from being completely separated from the wheelchair assembly in accordance with the misplacement problem described above. 
     With reference to  FIG. 1 , the wheelchair includes a pair of identical side frames A. Front wheel assemblies B and leg support assembles C 1  and C 2  are connected to a forward portion of the side frames. A folding mechanism D selectively enables the side frames to be moved together for more compact storage and easier handling. A seat E supports the operator. Selectively removable arm rest assemblies F are pivotally connected to the side frames to enable the arm support to be either pivoted relative to the frame or completely removed. A real wheel and curb step mounting assembly G selectively mounts rear wheels to the side frame and reinforces their interconnection. 
     With particular reference to  FIG. 2 , the side frames A are each constructed of relatively thin walled, light weight tubing, such as aluminum, magnesium, titanium and their alloys. Thin walled steel tubing is also contemplated. Because the left and right side frames are identical, to simplify inventory demands, only one of the side frames will be described in detail and it is to be appreciated that the description applies equally to both. the side frame consists of only a first generally L-shaped tubing section  10  and a second generally L-shaped tubing section  12 . The first L-shaped tubing section includes a first or forward generally vertically disposed tubular portion or forward leg  14  which is integrally connected by a bend with a first or upper generally horizontally disposed tubular portion or leg  16 . The second L-shaped tubing section includes a second or rearward generally vertically disposed tubular portion or leg  18  and a second or lower generally horizontally disposed tubular portion or leg  20 . The L-shaped tubing sections are welded at a forward lower interconnection  22  and a rearward upper interconnection  24 . The forward, lower weld junction is reinforced by the front wheel mounting assembly B and the rearward upper weld joint is reinforced by the arm support assemblies F. This reinforcing of the welds with other assemblies facilitates the use of lighter weight tubing without sacrificing the reliability and durability of tubing junctions. In the preferred embodiment, the second, rearward vertical tubular portion extends upward beyond the upper rearward weld  24  to mount a portion of the seat E thereon. Optionally, a separate tubing portion may be interconnected to the side frame by a hinge or the like to support the upper seat portion. 
     The front wheel assemblies B are each connected with a corresponding one of the side frames A. A reinforcing tube  30  is slidably received in the front, vertical side frame tubing portion  14  to provide greater structure strength. A front wheel mounting bracket  32  is mounted to the side frame adjacent the forward, lower weld  22  to mount front wheel casters and to reinforce the weld. More specifically, the front wheel assembly mount includes a generally U-shaped bracket  34  to which a tubular portion  36  is welded. The bracket  34  and the tubular portion  36  are configured and interconnected to be symmetric about a horizontal axis such that the mount can be rotated top for bottom and used on the opposite side of the chair. Mechanical fasteners  38  extend through corresponding bores in the U-shaped bracket  34 , the side frame forward, vertical tubular frame portion  14  and the lower horizontal frame portion  20 , and the reinforcing tube  30 . The mechanical fasteners may be bolts, pop-rivets or the like. A front wheel caster  40  has an upstanding post  42  which is mounted by appropriate bearings and other mounting means  44  to the front wheel mounting assembly bracket tube  36 . Due to the symmetry of the mount, the stud  42  and the bearings and other mounting structures  44  may be inserted into the tubular portion  36  from either direction to enable the same parts to be used as either a right or left front wheel assembly. 
     With continuing reference to  FIG. 2 , the front leg support assembly C includes a mounting bracket  50  which is interconnected by mechanical fasteners  52  with corresponding apertures in the front generally vertical tubular frame portion  14  and the reinforcing tube  30 . Each leg rest mounting bracket includes a pair of cams  54  which have pivot pins  56  at one end and locking surfaces  58  at their other ends. Optionally, the pivot pins  56  may extend symmetrically through the cam surfaces to enable the bracket  50  to be inverted top to bottom for placement on the opposite side of the frame. 
     An upper leg support mounting member  60  has a pair of hinge plates  62  that have apertures for receiving pins  56  of the mounting bracket  50 . A spring biased cam follower assembly  64  is pivotally mounted to one of the hinge plates such that a spring biases a follower portion  66  thereof against the corresponding one of cams  54 . The cam follower portion  66  is spring biased to lock behind the locking surfaces  58  when the leg support member is facing straightforward. By pressing a manual, release lever  68 , the cam follower  66  is biased against the spring out of contact with the stop surfaces  58  to allow the leg assembly to pivot on pivot pins  56 . The hinge members  62  may be asymmetric to limit their mounting to the left or right side of the chair to prevent the leg rest assemblies from being mounted backwards. Optionally, the hinge members may be symmetric about a central axis and define pivot holes on either side thereof. The symmetric positioning of holes for the cam follower enables the leg rest to be mounted on either side of the chair. 
     With continuing reference to  FIG. 2  and further reference to  FIG. 3 , a foot support extension tube  70  is telescopically received in portion  60  with a degree of telescopic receipt set by a clamping means  72 . A generally U-shaped foot rest member  74  is connected by mechanical fasteners  76  to a mounting bracket  78 . The generally U-shaped member  74  and the mounting bracket  78  are the same for both left and right side foot rests, but their interconnection is reversed by 180 degrees. Another mechanical fastener  80  pivotally interconnects the bracket  78  with the extension tube  70 . A solid plus  82  provides increased structural strength to the lower end of tube  70 . An adjustable stop, such as a bolt  84  is tapped into the plug  82  and abuts the bracket  78 . By adjusting the distance with which the stop  84  extends from the plug  82 , the rest position of the foot rest is selectively adjustable. 
     A molded plastic foot rest cover  86  slides over the U-shaped tube  74  and is anchored thereto by a post  88 . A foot support strap  90  is telescopically received over the extension tube  70  and the post  88 . The post  88  is mounted symmetrically in the U-shaped portion  74  such that the foot rest cover  86  may be utilized with either the left or right side. 
     With continuing reference to  FIG. 1  and further to  FIGS. 4 and 5 , the folding mechanism D is interconnected with the side frames A and the seat E. The folding mechanism includes to identical generally T-shaped seat support structures  100 . Each seat support structure includes a seat support member  104 . The cross brace member is interconnected with the seat support member  104  offset from its center such that the seat side support member  102  defines a longer free end  106  and a shorter free end  108 . The cross brace members are interconnected by a pivot joint  110  which may include a nylon spacer or the like  112  between the cross members. The relative lengths of the longer and shorter free ends are selected relative to the diameter of the cross brace members and the thickness of any washer  112  such that the forward most ends of the seat support member are parallel and the rearward most ends of the seat support members are parallel. 
     A fitting  120  is interconnected with the lower end of each cross member for rotatable interconnection with the lower horizontal side frame tubular portion  20 . More specifically, the fitting  120  defines a side frame receiving passage  122  extending longitudinally therefore for rotatably receiving the tubular side frame portion. To maintain the horizontal side frame portion and the folding mechanism in proper alignment, the fitting defines a groove  124  extending circumferentially. A projection  126 , such as a pop rivet mounted to the side frame, is slidably received in the circumferentially extending groove. The groove is offset in the same direction as the longer free end  106  of the seat support structure such that it is substantially in alignment across the chair. Both side frames have an aperture bored in the same place the same distance from the front of the frame to receive the mechanical fastener  126 . In this manner, the reversibility of the side frames is assured. 
     As alignment link  130  is pivotally connected at one end with the cross member  104  and has a fitting or connection  132  at its other end which defines an upper generally horizontal extending frame side tube passage  134 . The fitting  132  defines a circumferentially extending groove or slot  136  which receives a projection  138  projecting from the upper, horizontally extending tubular side frame portion  16 . The circumferentially extending groove or slot  136  is again aligned with the center of the pivot washer  112  such that bores or apertures for the projections  138  are in the same location on both left and right side frames. This enables the side frames to be interchanged without boring additional apertures. 
     With reference again to  FIG. 1 , the seat E includes a lower seat portion  150  of flexible cloth which is anchored by screws  152  or the like to the seat side supports  102 . A seat back portion  154  wraps around and is secured to the rear generally vertical side frame tubular members  18  and telescopically received hand grip portions  156 . 
     With continuing reference to  FIG. 1  and further reference to  FIGS. 8 and 9 , the arm support structure F includes an arm support member  160  such as a generally U-shaped tube upon which the user&#39;s arm may rest. A rearward end of the arm support structure is connected with a first mounting bracket  162  that has a portion  164  which is pivotal relative to the side frames. More specifically, a combined seat side support receiving cradle, weld reinforcing member and first mounting bracket base  166  is connected with the side frame adjacent upper rearward weld  24  to reinforce the weld, support the seat side support  102  when the chair is open, and to have the portion  164  pivotally mounted thereon. A stop  168  limits pivoting movement of the first mounting bracket. A spring detent  170  and release means  172  or other means for releasably securing the arm supporting structure rear end to the first mounting bracket permits the arm support structure to be selectively disconnected therefrom. 
     Referring again now to the drawings, and to  FIG. 4 , rewind mechanisms  300 , 301  are described. A housing comprises first portion  360  in which the rewind mechanism is mounted and a second portion (not depicted for illustrative purposes) that closes the housing. The second portion is attached to the first portion, for example, by gluing, welding or an inner lip which is press fit into the first portion  360  as is well known in the art. 
     Flexible member  304  is wound around the central axis  355  of spool  352 . For illustrative purposes, only a segment of flexible member  304  is shown. However, one of ordinary skill in the art will realize that nearly any desired length of flexible member  304  may be wound onto spool  352  depending upon the dimensions of spool  352 . 
     Spool  352  is rotatably mounted within housing  360  as is well known in the art. Spool  352  is biased to rotate in a clockwise direction by a biasing element, for example, a helix, torsion or coil spring (not shown), as is well known in the art. Exemplary manners for biasing spool  352  to rotate are described in U.S. Pat. Nos. 2,521,178 to Meleth (see  FIG. 1  and corresponding description) 5,481,607 to Hsiao (see  FIG. 5  and corresponding description), 6,536,697 to Tsan (see  FIGS. 3 and 7  and corresponding description) and 6,736,346 to Park (see  FIG. 3  and corresponding description); all of which are fully incorporated herein by reference. The biasing element (not shown) rotates spool  352  in order to rewind flexible member  304  after it has been pulled out of housing  360 . As is well understood by one of ordinary skill in the art the rotation direction of the biasing element could be reversed with simple modifications to teeth  350  on spool  352 , to stop arm  330  and to the biasing element (not shown). 
     The legrest assemblies are connected to flexible member  304  and prevent flexible member  304  from being completely wound around central axis  355 . This prevents flexible member  304  from being completely withdrawn within housing  360  where a user cannot grasp it. 
     Another manner for preventing flexible member  304  from completely withdrawing into housing  360  is to configure the biasing element to stop rewinding before a free end of flexible member  304  disappears into housing  360 . 
     Arm  320  is pivotally mounted about pin  335  within housing  360 . In  FIG. 1 , pin  335  is molded as an integral part of housing  360 . Pin  335  could also be fixed to housing  360  in any well known manner such as, but not limited to, a bolt or other threaded fastener, gluing, welding or a rivet. A spring  340  engages arm  320  and housing  360  via post  345 . Spring  340  biases arm  320  towards spool  352 . Alternatively, arm  320 , or select portions of arm  320 , are made from an elastic material, for example a flexible plastic or spring steel. In these alternative embodiments, arm  320  is rigidly attached to pin  335 , or directly to housing  360 . In these alternative embodiments, spring  340  is not needed to bias arm  320  towards spool  352  as the elastic deformation of arm  320  will bias arm  320  towards spool  352 . 
     Arm  320  is configured with an opening containing a post  325 . In  FIG. 1  post  325  is fixed at both ends to arm  320  and is made from a smooth material that provides frictional engagement with flexible member  304 . For example, depending upon the amount of friction required to move arm  320 , post  325  can be made of a hard material, for example a hard plastic covered with a softer plastic or a durable rubber such as Santoprene R . An alternative construction for post  325  is to make post  325  with a rotatable cover over it, for example a bushing or nylon sleeve, which will provide frictional engagement for flexible member  304  and decrease the wear caused by flexible member  304  passing over post  325 . 
     An alternate construction for post  325  within arm  320  is to place post  325  in a position (for example, moving post  325  in the direction towards guide post  322 ) where flexible member  304  engages, e.g., is pinched by, both post  325  and arm  320 . For such an embodiment, arm  320  does not need to be made from a flexible material and spring  340  is not needed. The force of flexible member  304  moving between post  325  and arm  320  is sufficient to rotate arm  320  away from spool  352  when flexible member  304  is pulled. The force of flexible member  304  moving between post  325  and arm  320  is also sufficient to rotate arm  320  towards spool  352  when flexible member  304  is rewound by the biasing element (not shown). In such an embodiment, there is always resistance to movement of flexible member  304 . Referring to  FIG. 5 , such an embodiment placing constant resistance to movement of flexible member  304  is made, for example, by wrapping one or more complete turns of flexible member  304  onto guide roller  325 . 
     Referring again to  FIG. 1 , flexible member  304  is positioned through the opening in arm  320  and interacts with post  325  in such a manner that pulling on flexible member  304  places a force (Force A in  FIGS. 2 and 4 ), for example through friction, on post  325 . The force resulting from pulling flexible member  304  outside housing  360  overcomes the biasing force from spring  340  (or the internal force of arm  320  if it is a flexible material rigidly attached to pin  335  or housing  360 ) and causes arm  320  to rotate away from spool  352 . 
     Guide post  322  on arm  320  is configured to interact with a track  375  contained on plate  370 . Stop arm  330  on arm  320  is configured to interact with teeth  350  on spool  352  in a manner that prevents the biasing element (not shown) from rotating spool  352 . The present invention is not limited to a ratchet and pawl type stop mechanism, but uses any suitable mechanism such as frictional engagement or a post that fits into grooves or holes, for example. 
     Plate  370  is slidably mounted within housing  360  on posts  365 . Other manners for slidably mounting plate  370 , for example, on a flexible beam extending from a wall of housing  360 , or a ball joint sliding within a groove are also covered by the present invention. As arm  320  and guide post  322  rotate away from and towards spool  352  guide post  322  impacts walls within track  375 . Guide post  322  impacting the walls within track  375  causes plate  370  to slide on posts  365  which permits guide post  322  to move between positions C, D, B and A within track  375 . Alternatively, guide post  322  and/or arm  320  (or select portions of arm  320 ), can be made from an elastic material (as described above) and plate  370  can be fixedly mounted within housing  360 . Such an embodiment permits guide post  322  to move between positions C, D, B and A by impacting walls within plate  370  and deflecting enough to be guided to one of positions C, D, B or A. Another alternative construction used with an elastic guide post  322  and/or arm  320  is to make track  375  directly in the wall of housing  360  so that no plate  370  is required. In  FIG. 4  track  375  is depicted with an opening to the outside of plate  370 . the opening to the outside of plate  370  is to facilitate assembling the rewind mechanism  35  by making it easier to insert guide post  322  into track  375 . The opening to the outside of plate  370  is not necessary to the functioning of rewind mechanism  5 . 
     Referring now to  FIG. 4 , operation of the depicted embodiment of the inventive rewind mechanism  5  is described. With flexible member  304  fully wound around central axis  355 , e.g., with attachment device  310  abutting housing  360  or with the biasing element (not shown) not exerting any rotational force upon spool  352 , guide post  322  rests in position C within track  375  as depicted in  FIG. 1 . While guide post  322  rests in position C, stop arm  330  does not interact with teeth  350  on spool  352 . 
     Flexible member  304  is pulled from housing  360  which exerts Force A upon post  325 . The force upon post  325  is sufficient to overcome the force exerted by spring  340 , or the internal stiffness of arm  320  if it is rigidly attached to pin  335  or housing  360  in other embodiments, and causes arm  320  to rotate away from spool  352 . As arm  320  rotates away from spool  352  guide post  322  moves within tract  375 , impacts a wall within track  375  sliding plate  370  on posts  365  and relocating to position D. While flexible member  304  is being pulled from housing  360  guide post  322  remains in position D. Stop arm  330  remains free from engaging teeth  350  and spool  352  rotates as flexible member  304  is pulled from housing  360 . Pulling flexible member  304  also transfers mechanical energy to the biasing element (not shown) so that the biasing element has enough energy to completely rewind the flexible member  304  about central axis  355 . 
     When flexible member  304  is no longer pulled from housing  360  Force A exerted on post  325  subsides and spring  340 , or the internal stiffness of arm  320 , or the resistance to movement of flexible member  304  through arm  320 , causes arm  320  to rotate towards spool  352 . As arm  320  moves towards spool  352  the biasing element (not shown) rotates spools  352  and rewinds a small amount of flexible member  304  about central axis  355 . Guide post  322  impacts a wall within tract  375  sliding plate  370  on posts  365  and moving from position D to position A. As illustrated in  FIG. 3 , arm  320  is still rotating towards spool  352 , and guide post  322  is moving into position A. As illustrated in  FIG. 3 , arm  320  is still rotating towards spool  352 , and guide post  322  in moving into position A. Alternatively, guide post  322  and/or arm  320  have enough flex to move through track  375  when plate  370  is fixedly mounted within housing  360  or when track  375  is directly formed in a wall of housing  360 . With guide post  322  in position A, stop arm  330  interacts with teeth  350  to prevent spool  352  from rotating and further rewinding flexible member  304  about central axis  355 . While guide post  322  remains in position A stop arm  330  prevents spool  352  from rotating due to the force exerted by the biasing element (not shown). The portion of flexible member  304  which was pulled from housing  360  remains outside housing  360  without any tension placed on it by the biasing element (not shown). 
     When it is desired to rewind flexible member  304  about central axis  355  within housing  360  an additional amount of flexible member  304  is pulled from housing  360 . This exerts Force A upon post  325  which, again, is sufficient to overcome the force exerted by spring  340 , or the internal stiffness of arm  320  if it is rigidly attached to pin  335  or housing  360 , causing arm  320  to rotate away from spool  352 . As arm  320  rotates away from spool  352  guide post  322  moves within track  375 , impacts a wall within track  375  sliding plate  370  on posts  365  and relocates to position B. While the additional amount of flexible member  304  is being pulled from housing  360  guide post  322  remains in position B. Stop arm  330  is moved free from engaging teeth  350  and spool  352  rotates as flexible member  304  is pulled from housing  360 . Pulling flexible member  304  also transfers additional mechanical energy to the biasing element (not shown) so that the biasing element has enough energy to completely rewind flexible member  304  about central axis  355 . 
     After an additional amount of flexible member  304  is pulled from housing  360  flexible member  304  is released. The Force A exerted on post  325  subsides and spring  340 , or the internal stiffness of arm  320 , causes arm  320  to rotate towards spool  352 . As arm  320  moves towards spool  352  the biasing element (not shown) rotates spool  352  and rewinds flexible member  304  about central axis  355 . Guide post  322  impacts a wall within tract  375  sliding plate  370  on posts  365  and moves from position B to position C. Stop arm  330  is held free from teeth  350  to allow spool  352  to rotate and further rewind flexible member  304  about central axis  355 . The portion of flexible member  304  which was pulled from housing  360  is rewound within housing  360  by the biasing element (not shown). 
     Flexible member  304  can be completely rewound into housing  360  while guide post  322  remains in position C. Rewinding stops when attachment device  310  abuts housing  360 , or when the biasing element stops rotating spool  352 —depending upon the design as discussed above. Additionally, rewinding can be interrupted by pulling on flexible member  304 . Guide post  322  will then move to position A, as described above in relation to  FIG. 3 , when flexible member  304  is no longer pulled. Any portion of flexible member  304  that is outside housing  360  will remain outside housing  360  at this time. Thus, the portion of flexible member  304  outside housing  360  can be shortened (or lengthened) without first rewinding all of flexible member  304  into housing  360 . 
     The embodiment of the inventive rewind mechanism depicted in  FIG. 4  is also designed to prevent flexible member  304  from becoming locked outside housing  360 . One end of flexible member  304  is securely attached to spool  352  as is well known in the art. Thus, it is possible to pull flexible member  304  outside housing  360  until only the portion of flexible member extending from its attachment point to spool  352  to the opening in housing  360  remains within housing  360 . In the event that flexible member  304  is pulled this far outside housing  360  the distance guide post  322  must move from position D to position A within track  375  is far enough to rewind a sufficient amount of flexible member  304  onto spool  352  to permit guide post  322  to move from position A to position B. Thus, pulling out too much of flexible member  304  to prevent guide post  322  from moving between positions C, D, B and A within track  375  is avoided.