Abstract:
A wheelchair drive mechanism having a transmission providing forward, rearward and neutral motion through movement of a drive arm in an arcuate path.

Description:
FIELD OF THE INVENTION 
     The following invention is generally related to instrumentalities and methodologies used in wheelchair propulsion. More specifically, the instant invention is directed to an apparatus and method for utilizing a gear drive assembly to aid in human propulsion of a wheelchair. 
     BACKGROUND OF THE INVENTION 
     The following invention reflects applicant&#39;s ongoing efforts at improving wheelchair propulsion devices. 
     The following prior art reflects the state of the art of which applicant is aware and is included herewith to discharge applicant&#39;s acknowledged duty to disclose relevant prior art. It is stipulated, however, that none of these references teach singly nor render obvious when considered in any conceivable combination the nexus of the instant invention as disclosed in greater detail hereinafter and as particularly claimed. 
     
       
         
               
               
               
               
             
               
             
               
               
               
               
             
               
             
               
               
               
               
             
           
               
                   
                   
               
               
                   
                 PATENT NO. 
                 ISSUE DATE 
                 INVENTOR 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
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                 6,007,082 
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                 FOREIGN PATENT DOCUMENTS 
               
             
          
           
               
                   
                 EP 0497 999 A1 
                 August 12, 1992 
                 Chang 
               
               
                   
                   
               
             
          
         
       
     
     SUMMARY OF THE INVENTION 
     The present invention represents the inventor&#39;s constant evolving odyssey in providing solutions that continue to satisfy the needs of those with physical challenges. 
     A gear train is disclosed in the hub of each wheel of a wheelchair. The gear train includes linkage to a hand area of the chair to provide easy shifting between forward, reverse and neutral. The hand area allows power to be transferred to the wheels from a user&#39;s arms to move the wheelchair. 
     OBJECTS OF THE INVENTION 
     Accordingly, it is a primary object of the present invention to provide a new and novel device and method for human propulsion of a wheelchair. 
     It is a further object of the present invention to provide a device and method as characterized above which is simple to assemble and maintain. 
     It is a further object of the present invention to provide a device and method as characterized above which promotes self-reliance and independence. 
     Viewed from a first vantage point, it is an object of the present invention to provide a wheelchair, comprising, in combination: a frame; a seat on said frame; a pair of lead wheels on said frame; a pair of drive wheels on said frame; a pair of driver arms coupled to said drive wheels; and transmission means coupled between said driver arms and said wheels to induce either forward or reverse motion upon driver arm activation. 
    
    
     These and other objects will be made manifest when considering the following detailed specification when taken in conjunction with the appended drawing figures. 
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of the wheelchair according to the present invention. 
     FIG. 1A is a perspective view similar to FIG. 1 with the drive mechanism oriented in a second position. 
     FIG. 2 is a detail showing mounting of the drive and wheel assembly onto the wheel chair frame. 
     FIG. 3 is a perspective view of the drive arm and gear mechanism. 
     FIG. 4 is a second view thereof. 
     FIG. 5 is an exploded parts view of the drive mechanism. 
     FIG. 6 is a perspective view of a component thereof. 
     FIG. 7 is a front view depicting the drive mechanism in forward. 
     FIG. 7A is a perspective view. 
     FIG. 7B details the pinion  78  of FIGS.  5  and  7 - 11 . 
     FIG. 8 is a similar view to FIG. 7 showing one range of stroke. 
     FIG. 8A is a perspective view thereof. 
     FIG. 9 shows the transmission in neutral. 
     FIG. 10 shows the transmission in reverse. 
     FIG. 10A shows a perspective view of FIG.  10 . 
     FIG. 11 is a further view of FIG.  10 . 
     FIG. 11A is a perspective view of FIG.  11 . 
     FIG. 12 is a view particularizing the details of the adjustable handle. 
     FIG. 13 shows a brake pad. 
     FIG. 13A is a similar view with the brake pad actuated. 
     FIG. 14 is a view of one of the components of FIG.  5 . 
     FIG. 15 is a sectional view taken along lines  15 — 15  of FIG.  14 . 
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS 
     Considering the drawings, wherein like reference numerals denote like parts throughout the various drawing figures, reference numeral  10  (FIG. 5) is directed to the drive assembly according to the present invention. 
     In its essence, the drive assembly  10  propels a wheelchair. As shown in FIG. 1, the wheelchair  100  includes a seat portion  102  mounted on two horizontal frame rails  104 , the ends of which are connected to two vertical frame rails  106  on which a back portion  108  is mounted. One end of each vertical frame rail  106  terminates in a handlebar  110  for pushing the wheelchair  100 . A pair of foot platforms  112  depend from forward downward links  105  of the horizontal frame rails  104 . The foot platform supports the user&#39;s foot and may be rigidly attached or may pivot along Arrow Z to a storage position adjacent links  105 . Wheel attachment frames  116  (FIG. 2) also depend from the horizontal frame rails  104 , and include an elongate, horizontal, slot-like aperture  118  to secure an exposed end of wheel shaft  12  when a wheel  120  is to be attached. Each wheel attachment frame  116  includes two vertical struts  115  depending from horizontal frame rails  104 , and terminating in a horizontal frame rail member  117  paralleling horizontal frame rail  104  and below slot-like aperture  118 . Aperture  118  is supported on a plate  119  which spans struts  115 . Rail member  117  terminates forwardly in a vertical rod  113 , extending between horizontal frame rail  104  and rail  117  and supporting at a lower end a caster sleeve  111  which receives caster type wheel  114 . 
     Each of the two wheels  120  contains a recessed hub  126  (FIG. 5) about the central hub opening  128 . Slots  124  radiate outwardly from the central hub opening  128  to receive the drive casing  20  and permit motion. 
     One (outboard) side of each wheel  120  is covered with a face plate  90  (FIG.  1 ). The wheel shaft  12  projects from the other side, terminating in the exposed end  16  (FIG.  2 ). The side with the face plate  90  is the exterior side when the wheel  120  is mounted on the wheelchair  100 . The wheel  120  is attached by threading the exposed end  16  of the wheel shaft  12  through the aperture  118  in the wheel attachment areas  116  underneath the seat portion  102 . A square locking nut  4  (or alternatively guide bushing) is placed on the exposed end  16  of the wheel shaft  12 , and, preferably, a quick-release cam  2  is inserted into the end of the wheel shaft  12 . Two bearings  6  locate shaft  12  precisely within central exterior sleeve of drive casing  20  and through gore  3  of nut  4 . Cam  2  threads into a threaded gore of shaft  12  and pivots on cam  2  allows rotation of the cam to lock on nut  4 . Tab  5  on cam  2  helps in rotation. 
     With reference to FIG. 5, depicting the exterior side of the wheel  120 , a drive casing  20  having the same shape as the recessed hub  126  is inserted into the recessed hub  126 . The drive casing  20  also has a brake surface  30  which coincides with the outer periphery of the recessed hub  126 . Protruding drive splines  22  are present on the exterior side of the drive casing  20  on sleeve  24 , and these drive splines  22  engage the slots  124  in the hub  122  when the drive casing  20  is inserted into the recessed hub  126 . 
     A crank assembly  40  is located on the other side of the drive casing  20 , allowing the occupant to utilize forward (FIGS. 7,  7 A,  8 ,  8 A), reverse (FIGS. 10,  10 A,  11 ), and neutral (FIG. 9) modes of operation. A drive assembly  60  is then mounted on the interior end of the wheel shaft  12 , and a face plate  90 , secured with an outside bolt  92  threaded to shaft  12 , covers the hub  126 . 
     The exterior side of the drive casing  20  includes a centrally-located exterior sleeve  24 ; the drive splines  22  radiate outward from the exterior sleeve  24 . The exterior sleeve  24  engages the central hub opening  128 , while the drive splines  22  engage the slots  124  that extend radially from the central hub opening  128 . An interior wheel shaft bearing  6  is contained within the exterior sleeve  24 . A centrally-located interior sleeve  28  projects into the interior portion of the drive casing  20 . An inner gear  32  formed as an annular band encircles the interior sleeve  28  of the drive casing  20 . Teeth of gear  32  are found on the outer periphery. An outer gear  34  formed as an annular band in the teeth on an inner band portion is mounted on the inner circumferential surface  29  of the drive casing  20 . 
     The crank assembly  40  contains a crank housing  42  which encases a shift link  46 , covered by a crank cover  54 . The crank housing  42  also includes a keyway  44  to receive and secure the drive assembly  60 . The shift link  46  has a knob support  48  at one end and a spindle retainer  52  at the other end. The knob support  48  extends through the crank housing  42  and is connected to a shift knob  56  and is constrained in a shift gate  50 , which allows selection of forward, reverse, and neutral modes of operation. The spindle retainer  52  is connected to a spindle  74  on toggle  70 . Attached to the crank housing  42  adjacent the seat portion  102  of the wheelchair  100  is a pivotably adjustable handle (FIG. 12)  58 , which allows the occupant to control the wheelchair  100 . The crank cover  54  contains a brake pad  55  (FIGS. 13 and 13A) that contacts the brake surface  30  of the drive casing  20  when the handle  58  is pulled toward the wheelchair  100  by its occupant, shown in FIGS. 12,  13 , and  13 A. Handle  58  includes a ball  59  threaded into the handle. Ball  59  is received in socket  61  threaded into crank  42 . 
     The wheel shaft  12  passes through the exterior wheel shaft bearing  26 , the drive casing  20 , and the interior wheel shaft bearing  6  to engage with the quick-release cam  2  through the square locking nut  4 . The end of the wheel shaft  12  under the seat portion  102  of the wheelchair  100  contains a box-shaped yoke mount  14 , designed to accommodate a support yoke  36 , which keeps the wheel shaft  12  from flexing under load. As shown in FIGS. 14-15, the support yoke  36  includes adjustable stops  38 , held in place by set screws  39 , to limit motion of the handle  58  by the occupant if the handle is dropped while the shift knob  56  is in the neutral position (e.g. FIG.  1 A). These stops  38  may be adjusted using the set screws  39  to best suit the needs of the occupant. 
     The drive assembly  60  contains a drive link  62 , upon which is mounted a shifting toggle  70  via fulcrum  72  passing through support hole  63 . The drive link  62  is shaped to include a key  64  that registers in the keyway  44  in the crank housing  42 . When the drive link  62  is so placed, the key  64  is secured with a pin  66  in the keyway  44 . The shifting toggle  70  includes a shift spindle  74  and a pinion spindle  76 , one on each side of a fulcrum  72 . The shift spindle  74  is connected to the spindle retainer  52  on the shift link  46 . The pinion spindle  76  has a pinion  78  mounted upon it, and the pinion  78  is located between the inner gear  32  and the outer gear  34  in the drive casing  20  when the drive assembly  60  is installed. The connection of the shift link  46  to the shift spindle  74  in the drive assembly  60  allows the pinion  78  to engage the inner gear  32  or the outer gear  34 , depending on the orientation of the shift knob  56 . This allows the wheelchair  100  to move in a forward or reverse direction. 
     The wheelchair  100  is propelled by using the pivotable handles  58 , connected to the crank assemblies  40 , which are attached to each wheel  120 . The drive mechanism  10  translates this motion to the wheels  120 . When the wheelchair  100  is in a particular gear (e.g., forward or reverse), motion in any other direction is prevented by the pinion  78 . FIG. 7B shows that the pinion  78  includes an interior unidirectional pawl  79  biased via springs  77  to engage teeth  81  only in one direction. Thus, the pinion  78  connects with either inner gear  32  or outer gear  34  for driving engagement. The pinion  78  when engaged, permits rotation in one direction only, preventing slippage of the wheel  120  in a direction other than that desired. When the neutral gear is selected, freewheeling, or motion in either direction, is allowed. 
     Preferably, the shift gate  50  has a forward position  94 , a reverse position  96 , and a neutral position  98 . When the shift knob  56  is in the neutral position  98  (FIG.  9 ), the pinion  78  engages neither the inner gear  32  nor the outer gear  34 . Thus, the wheel  120  may freely rotate in either direction. When the shift knob  56  is moved into the reverse position  96 , the shift link  46  moves the shift spindle  74  and the pinion spindle  76  about the fulcrum  72  such that the pinion  78  contacts the inner gear  32  (FIGS. 10,  10 A). When the crank assembly  40  is moved from the position shown in FIG. 10 to that shown in FIG. 11, the inner gear  32  rotates which causes the wheel  120  to also move. 
     To utilize the forward direction, the shift knob  56  is moved to the forward position  94  in the shift gate  50 . This motion translates through the fulcrum  72  such that the pinion  78  registers with the outer gear  34 . When the pinion  78  is so engaged and the crank assembly  40  is moved by the occupant using the pivotable handle  58  (FIG.  8 ), the outer gear  34  moves causing the wheel to move in the forward direction. 
     Moreover, having thus described the invention, it should be apparent that numerous structural modifications and adaptations may be resorted to without departing from the scope and fair meaning of the instant invention as set forth hereinabove and as described hereinbelow by the claims.