Abstract:
The present invention is a connector assembly for use in coupling a wheelchair to a wheelchair lift. The assembly includes a lift connector which has a lower arm and an upper arm, with each arm having first and second ends. An end link joins the first ends of the lower and upper arms, and the second end of each arm is free. A chair mount is removably connectable to the second free end of the lower arm of the lift connector, and is secured to a wheelchair. A lift mount is selectively positionable along the upper arm of the lift connector and is adapted to be coupled to a wheelchair lift.

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) 
     The application claims priority from U.S. Provisional Application Ser. No. 60/106,678 filed Nov. 2, 1998 for “Wheelchair Docking Device” by Kary D. Conaway, Aaron H. Stegeman and Ronald F. Bechler. 
    
    
     BACKGROUND OF THE INVENTION 
     This invention relates to personal mobility vehicle and wheelchair accessories, and more specifically, to a removable docking device attachable to personal mobility vehicles and wheelchairs enabling quick connection to a lift that permits raising, shifting, and lowering of the vehicle or wheelchair into a transport vehicle. 
     Personal mobility vehicles have gained widespread acceptance for use by elderly persons or persons with partial or total disabilities. Self-propelled wheelchairs and scooters are among the most popular personal mobility vehicles. As the use of self-propelled wheelchairs has increased, so had the need to transport such wheelchairs to remote locations. Wheelchairs (whether manual or self-propelled) are typically transported and stored in the storage area or trunk of another transport vehicle, such as a minivan or automobile. 
     The transportation and storage of wheelchairs presents numerous problems. Transporting a wheelchair, which often weighs as much or more than the user, requires its placement inside the storage area of the transport vehicle. Since most wheelchair users are elderly or partially handicapped persons, manually lifting the cumbersome wheelchair into the transport vehicle storage area can be an arduous task. To rectify these problems, many wheelchair users employ complex mechanical lifting systems to raise, shift, and lower the unwieldily wheelchair into the transport vehicle. Examples of such lifting systems include hoists, winches, cranes, lifting springs, or any other appropriate lifting system and can be found in U.S. Pat. No. 5,431,526 to Peterson, U.S. Pat. No. 4,991,810 to Androus, and U.S. Pat. No. 5,205,700 to Lin. However, the prior art mandates a sophisticated level of manual dexterity to both assemble and operate these lifting systems. Additionally, prior art lift systems require substantial user strength to properly position the wheelchair. Typically, the user must manually maneuver (using both arms) the wheelchair into the transport vehicle. Further, prior art lifting systems are structurally limited as assembly and disassembly of these complex mechanical devices is often a complicated and time-consuming procedure. 
     To overcome the difficulties of the previous lifts, an easily-operable wheelchair lift requiring only one hand to raise and lower the wheelchair has been developed as found in U.S. Pat. No. 5,853,282 to Bechler et al. However, the lift still requires a mounting point attached to the wheelchair. Improper attachment would result in an unbalanced wheelchair causing tipping of the chair. In addition, a permanently mounted attachment device could obstruct the use of the chair. 
     BRIEF SUMMARY OF THE INVENTION 
     In the preferred embodiment of the present invention, a connector assembly is used to couple a wheelchair to a wheelchair lift. The connector assembly includes a lift connector. The lift connector has a lower arm and an upper arm, with each arm having first and second ends. An end link joins the first ends of the lower and upper arms, and the second end of each arm is free. A chair mount is removably connectable to the second free end of the lower arm of the lift connector, and is secured to a wheelchair. A lift mount is selectively positionable along the upper arm of the lift connector and is adapted to be coupled to a wheelchair lift. Preferably, the lift mount is aligned at a point over the center of gravity of the wheelchair so that when the wheelchair is lifted using the docking device of the present invention, it does not tip. 
     The invention also includes the method of coupling a wheelchair to a device for elevating the wheelchair. This method includes providing a wheelchair having a chair mount permanently secured thereto, and aligning a portion of a lower arm of a lift connector to be selectively attached to the chair mount. The lift connector has an upper arm thereon which is spaced from the lower arm. The method further includes securing the lower arm of the lift connector to the chair lift, moving a lift mount along the upper arm of the lift connector, and attaching the lift mount to a device for elevating the wheelchair. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention will be further explained with reference to the attached figures, wherein like structures are referred to by like numerals throughout the several views. 
     FIG. 1 is a perspective view of a motorized wheelchair being held up by the scooter lift via the inventive docking device. 
     FIG. 2 is a perspective view of the inventive docking device, mounted to a cross brace portion of a wheelchair (with parts of the wheelchair removed or shown in phantom for clarity). 
     FIG. 3 is an exploded perspective view of the inventive docking device. 
     FIG. 4 is a cross-section side view of the T-slider locked in position on the C-arm. 
     FIG. 5 is a side view of the inventive docking device attached to a wheelchair with the C-arm separated from the offset extension tube. 
    
    
     While the above-identified drawings set forth several one preferred embodiment, other embodiments of the present invention area also contemplated, as noted in the discussion. This disclosure presents illustrative embodiments of the present invention by way of representation and not limitation. Numerous other modifications and embodiments can be devised by those skilled in the art which fall within the scope and spirit of the principles of this invention. 
     DETAILED DESCRIPTION 
     A docking device of the present invention is shown generally at  10  in FIG.  1 . The docking device  10  is secured at a lower end  12  to an electric wheelchair  14 . An upper end  16  of the docking device  10  is connected to a scooter lift  18 . The electric wheelchair  14  is lifted off the ground by the scooter lift  18  as described in U.S. Pat. No. 5,853,282 which is incorporated by reference herein. The docking device  10  provides quick attachment and unattachment of the docking device  10  to the scooter lift  18 . Additionally, portions of the docking device  10  are easily separated from the wheelchair and the remaining portions are unobtrusive when the wheelchair  14  is in use. The docking device  10  is attached to the lift  18  so that the lift  18  is holding the wheelchair  14  over the balance point of the wheelchair  14 . The docking device  10  thereby prevents tipping of the wheelchair  14  as it is being maneuvered in and out of a vehicle (not shown)being used to transport the wheelchair  14 . 
     Preferably the docking device  10  extends around a seat portion  20  of the electric wheelchair  14 . The upper end  16  extends over a horizontal top portion  20 A. The docking device  10  bends downwardly over a front edge  20 B and the lower end  12  thereof extends underneath a horizontal bottom portion  20 C. The lower end  12  attaches to a cross brace portion  22  positioned under the seat portion  20 , as best illustrated in FIG.  2 . 
     The cross brace  22  (or “brace”) is typically in the shape of an “X” and acts as a portion of the support frame for the wheelchair  14  (shown in phantom). The cross brace  22  has frame members  22 A and  22 B typically pinned at the intersection point with a pre-existing bolt (not shown). To attach the docking device  10 , that bolt is removed and replaced. A person skilled in the art would realize, however, that the cross brace  22  of the wheelchair  14  (or any other personal mobility device) need not necessarily be in the shape of an X. Any wheelchair frame which allowed for the mounting of the docking device thereon (preferably under the seat and in the center of the chair) would not depart from the spirit and scope of the invention. It should particularly be noted that the docking device does not require that the wheelchair be motorized—it works for manual wheelchairs, self-propelled wheelchairs and even other personal mobility aids for the elderly or persons with disabilities. 
     The docking device  10  includes a wheelchair adapter bracket  30 , an offset extension tube  32 , a C-arm  34 , and a T slider  36 . The adapter bracket  30  is mounted to the cross brace  22  by extending an adapter bolt  40  through a first arm  42  (on the adapter brace  30 ), further through the cross brace  22  (through the portion where the pre-existing bolt was removed) and finally through a second arm  44  (on the adapter brace  30 ), as illustrated in FIG.  3 . 
     The arms  42  and  44  extend downwardly from a bracket body  46  and are preferably approximately one inch wide. Preferably, the bracket body  46  is manufactured of a metal tube having a square interior cross-section (approximately one inch by one inch). The wall thickness of the tube of the body  46  is preferably approximately twelve gauge. The arms  42  and  44  are preferably approximately 2.62 inches apart. 
     The bracket body  46  runs longitudinally from a first end  48  to a second end  50 . The bracket body  46  is preferably approximately 3 inches long in the longitudinal direction. The first arm  42  extends downwardly from the first end  48 , perpendicular to the longitudinal direction of the bracket body  46 . The second arm  44  extends downwardly from the second end  50  of the bracket body  46  perpendicular to the longitudinal axis of the bracket body  46 . Both arms  42  and  44  extend from the first end  48  and the second end  50  preferably approximately 2.25 inches. Adapter bolt apertures  52 A and  52 B extend through the first arm  42  and second arm  44 , respectively. The apertures  52 A and  52 B are disposed through the distal end of each arm  42  and  44  (preferably approximately 1.75 inches from where the arms  42  and  44  are joined to the bracket body  46  and centered in the transverse direction). The diameter of each aperture  52 A and  52 B is preferably approximately 0.34 inches. The arms  42  and  44  are preferably welded to the bracket body  46 . 
     The adapter bracket  30  is disposed over the cross brace  22  of the wheelchair  14  so that the first and second arms  42  and  44  extend on opposite sides of the cross brace  22 . The adapter bolt  40  is extended through the adapter bolt apertures  52 A and  52 B and the cross brace  22  and secured in place using a lock nut  54 . Attaching the adapter bracket  30  to the cross brace  22  in this fashion positions the adapter bracket  30  (and consequently the docking device  10  in a central position relative to the wheelchair  14 ). 
     A pair of first extension tube apertures  56  extend transversely through the bracket body  46 , on opposite sides of the tube thereof. The first extension tube apertures  56  are preferably disposed in the middle (longitudinally and transversely) of opposing faces on the adaptor bracket body  46 . Preferably, the apertures  56  extend through faces on the bracket body  46  so that the first extension tube apertures  56  run in a direction perpendicular to the first and second arms  42  and  44 . Positioning the apertures  56  in this manner prevents the mounting of the offset extension tube  32  to the adapter bracket  30  from interfering with the cross brace  22 . The first extension tube aperture  56  has a diameter of preferably approximately 0.28 inches. 
     The offset extension tube  32  is preferably a square metal tube extending longitudinally from an adapter end  60  to a C-arm end  62 , with a length of preferably approximately 8.5 inches. The exterior cross sectional area of the tube is preferably approximately 0.75 inches by 0.75 inches and its wall thickness is preferably 11 gauge. The cross sectional area of the offset extension tube  32  is such that is can be disposed inside the bracket body  46  of the adapter bracket  30 . A pair of adapter bracket apertures  64  extend transversely through the offset extension tube  32 , approximately 1.5 inches from the adapter end  60  with each aperture  64  having a diameter of preferably approximately 0.28 inches. The adapter end  60  is disposed within the bracket body  46  of the adapter bracket  30  so that the adapter bracket apertures  64  in the offset extension tube  32  are aligned with the first extension tube apertures  56  in the adapter bracket  30 . An extension tube bolt  66  secures the offset extension tube  32  to the adapter bracket  30 . The extension tube bolt  66  extends through the first extension tube apertures  56  and the adapter bracket apertures  64  and is secured in place by a lock nut  56 . A pair of C-arm apertures  70  extend transversely through the offset extension tube  32 . The apertures  70  extend through the extension tube  32 , preferably approximately 1.5 inches from the C-arm end  62 . 
     The offset extension tube  32  is substantially “S” shaped. A first portion  72  of the extension tube  32  extends at least approximately three inches in a longitudinal direction towards the front of the wheelchair  14 . A second portion  74  of the tube  32  projects substantially upwardly and forwardly (relative to the wheelchair  14 ) approximately 0.75 inches closer to the seat portion  20 . A third portion  76  of the tube  32  extends generally parallel to the first portion  72 . The third portion  76  of the tube  32  extends forwardly for at least approximately 3 inches. 
     Similar to the adapter bracket  30 , the C-arm  34  is preferably formed from a square metal tube having a cross-sectional interior opening of preferably approximately one inch by one inch. The wall thickness of the tube defining the C-arm  34  is preferably approximately 12 gauge. The C-arm end  62  (male end) of the offset extension tube  32  is disposed into an extension tube end  80  (female end) of the C-arm  34 . A pair of second extension tube apertures  82  are disposed transversely through the C-arm  34 , preferably approximately two inches from the extension tube end  80 . For assembly the adapter bracket apertures  64  of the offset extension tube  32  are aligned with the second extension tube apertures  82  of the C-arm  34 . A locking pin  84  is disposed through the second extension tube apertures  82  and the adapter bracket apertures  64 , effectively locking the C-arm  34  in position relative to the offset extension tube  32 . Typically, the locking pin  84  has a tether attachment  86  which is fastened to the C-arm  34 . The tether attachment  86  is a flexible member such as a chain or string which is secured to the locking pin  84  at one end and a bracket  88  at the other end. The bracket  88  is then screwed to the C-arm  34  using a tether screw  90 . The locking pin  84  provides a readily securable, yet easily releasable means for securely connecting the offset extension tube  32  and C-arm  34 . 
     A first portion  92  of the C-arm  34  extends forward of the front edge  20 B of the seat portion  20  (shown in FIG.  1 ). The first portion  92  extends for preferably approximately eight inches. A second portion  94  extends upwardly (relative to the wheelchair  14 ) for preferably approximately 9 inches. The second portion extends generally parallel to the front edge  20 B of the seat portion  20 . A third portion  96  extends rearwardly for preferably approximately 19 inches. The third portion  96  of the C-arm  34  is preferably substantially parallel to and generally aligned over the first portion  92  of the C-shaped arm  34 . The C-arm thereby is substantially “C” shaped, and extends from the offset extension tube  32  located under the horizontal bottom seat portion  20 C upwardly past the front edge  20 B and then rearwardly so as to be disposed above the horizontal top portion  20 A of the wheelchair  14 . The third portion  96  of the C-arm  34  terminates at a slider end  98 . A stop screw  100  is disposed into the C-arm  34 , preferably approximately 0.38 inches from the slider end  98 . 
     The T-slider  36  includes a slider body  110 , a post  112  and a mating dowel  114 . The slider body  110  is a square metal tube having a cross-sectional interior area of preferably approximately 1.25 inches by 1.25 inches. The cross-sectional area of the open inside portion of the slider body  110  is large enough to accommodate the square tube defining the third portion  96  of the C-arm  34 . The slider body  110  encompasses the third portion  96  with enough clearance so that the T-slider  36  can be moved longitudinally along the length of the third portion  96  of the C-arm. The post  112  extends longitudinally upward from the slider body  110  (relative to the seat portion  20 ) preferably approximately 1.25 inches. The post  112  is preferably welded to the slider body  110  at a lower end  116 . The cross-sectional area of the post  112  is approximately 0.75 inches by 0.75 inches. The post  112  extends from the slider body  110  in an upward direction perpendicular to the longitudinal axis of the slider body  110  and terminates at an upper end  118 . The mating dowel  114  is fixed to the upper end  118  of the post  112 , preferably by welding. The mating dowel  114  runs perpendicularly to the longitudinal axis of the post  112  and in a direction perpendicular to the longitudinal axis of the third portion  96  of the C-arm  34 . The dowel  114  is adapted to be engaged with a gripping portion  120  (shown in FIG.  1  and described in U.S. Pat. No. 5,853,282) of the scooter lift  18 . A weld nut  122  is fixed to the slider body  110  so as to accommodate a locking bolt  124 . 
     The T-slider  36  (or lift mount) is adapted so as to be able to be slid by the operator along the third portion  96  of the C-arm  34  as illustrated in FIG.  4 . The T-slider  36  is adjustable along the C-arm  34  in the longitudinal direction as illustrated by arrows  126 A and  126 B. Sliding the T-slider  36  in this fashion allows the operator to position the T-slider  36  along the C-arm  34  at the balance point of the wheelchair  14 . This balance point would typically occur over the center of gravity of the wheelchair  14 . Once the T-slider  36  has been adjusted to the balance point so that the wheelchair  14  will not twist or rotate upon lifting, the T-slider  36  is locked in position along the C-arm  34 . The weld nut  122  is welded to the T-slider  36  over a slider aperture  128 . The locking bolt  124  is threaded through the weld nut  122 , and extends through the slider aperture  128 . The locking bolt  124  engages the C-arm  34  and can be tightened so as to hold the T-slider  36  in place with respect to the C-arm  34 . A person skilled in the art would realize that the weld nut  122  may not be attached, and instead the slider aperture  128  may be threaded to accommodate the locking bolt  124 , or that other alternative arrangements may be provided to lock the T-slider  36  in position on the C-arm  34 . The stop screw  100  (shown in FIG. 3) prevents the T-slider  36  from sliding off of the end of the C-arm  34 . The lift  18  is attached to the T-slider  36  and the chair  14  may be raised into a vehicle or lowered out of a vehicle. Since the C-arm  34  is positioned so that the third portion  96  extends directly above the first portion  92 , the chair  14  is prevented from tipping from side to side. After finding the balance point along the third portion  96  of the C-arm  34  and locking the T-slider  36  in place, the chair  14  is prevented from tipping from front to back. 
     As shown in FIG. 5, the C-arm  34  (or lift connector) can be removed from the adapter bracket  30  and offset extension tube  32  (or chair mount) portion of the docking device  10  by removing the locking pin  84  from the second extension tube apertures  82  on the C-arm  34  and the adapter bracket apertures  64  on the offset extension tube  32  and pulling in a forward direction (as indicated by arrow  140 ). Once the C-arm  34  and the T-slider  36  portion of the docking device  10  have been removed, a user can sit in the seat portion  20  of the wheelchair  14  without interference from the docking device  10 . The adapter bracket  30  and offset extension tube  32  portions of the docking device  10  remain attached to the wheelchair  14 , but remain out of the way underneath the front edge  20 B of the seat portion  20 . Re-attaching the C-arm  34  and the T-slider  36  requires sliding the extension tube end  80  of the C-arm  34  over the offset extension tube  32  rearwardly (in the direction of arrow  142 ). The locking pin  84  is then re-inserted through the second extension tube apertures  82  and the adapter bracket apertures  64 , effectively locking the upper portion of the docking device  10  in place and allowing easy access to attach the lift  18  to the T-slider  36 . 
     A person skilled in the art would realize that although dimensions have been provided for the preferred embodiment of the inventive docking device  10 , alternate dimensions may also be used without departing from the inventive spirit and scope. Additionally, square metal tubes need not be used to practice the invention. A person skilled in the art would realize that other tubing or bracket shapes manufactured from a variety of materials (plastic, for example) can be utilized. In addition, although one specific attachment arrangement is illustrated form connecting the inventive docking device to a lift (mating dowel  114 /post  112  and gripping device  120 ), numerous other connecting arrangements will work to releasably secure the lift to the docking device over the center of gravity of the wheelchair. Indeed, numerous other arrangements will work to practice the invention of finding and then using the central balance point of the wheelchair for ease in lifting the wheelchair. That invention and its method of use should not be limited in scope by the particular form or mechanics of the embodiment used to illustrate it. 
     Although the present invention has been described with reference to preferred embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention.