Patent Publication Number: US-2007096427-A1

Title: Powered attachment for a wheelchair

Description:
This Application claims the benefit pursuant to 35 U.S.C. 119(e) of U.S. Provisional Patent Application Ser. No. 60/726,850 filed by the applicant on Oct. 14, 2005 
    
    
     FIELD OF THE INVENTION  
      This invention relates to wheelchairs and, and more particularly, to a powered attachment for a wheelchair.  
     DISCUSSION OF RELATED ART  
      Means for providing auxiliary power to a manually-driven wheelchair are known in the art. Such devices are useful for extending the distance a person may travel without tiring, as manually propelling a wheelchair is a laborious task. Examples of such devices are found in the following prior art patents:  
                                       Patent Number   Inventor   Pub. Date                  U.S. Pat. No. 6,766,871   Sawyer   Jul. 27, 2004       U.S. Pat. No. 6,729,422   Chu et al.   May 4, 2004       U.S. Pat. No. 5,651,422   Casali   Jul. 29, 1997       U.S. Pat. No. 5,494,126   Meeker   Feb. 27, 1996       U.S. Pat. No. 5,113,959   Mastov et al.   May 19, 1992       U.S. Pat. No. 5,050,695   Kleinwolterink, Jr.   Sep. 24, 1991       U.S. Pat. No. 5,016,720   Coker   May 21, 1991       U.S. Pat. No. 4,050,533   Seamone   Sep. 27, 1977                  
 
      Such devices are typically characterized by a mechanism attachable to a wheelchair that provides a motorized drive wheel that can selectively contact the ground to drive the wheelchair in a forward or reverse direction. Several such devices additionally provide steering means, as well.  
      However, such devices are relatively difficult to detach from the wheelchair to which they are mounted, as is often desired in closed or tight spaces such as indoors. To the extent that such devices are usable indoors, however, such devices are not capable of powering the wheelchair to which they are attached to any significant distance or at a significant speed. Prior art devices of this type are characterized by a compact, relatively small drive wheel, and as such they are limited both in the safe maximum speed at which they can operate, and the irregularity of the surface over which they can travel. None of these prior art devices would be suitable, for example, traveling over a gravel or dirt path. In open or outdoor situations, such as when a person desired to travel to a local supermarket several blocks away, for example, such prior art devices do not provide enough speed to make the trip a practical, short expedition. Such devices typically can only propel a wheelchair at a rate of two or three miles per hour. Further, such prior art devices are not well-suited for outdoor travel over irregular sidewalks, up and down driveway curbs, or even over rough or irregular terrain such as grass or dirt due to the size of the drive wheels typical of such devices.  
      Other wheelchair powering attachments have been devised that include larger drive wheels, and as such overcome the difficulty of powering a wheelchair over rough or uneven terrain. Such prior art devices are taught in the following prior art references:  
                                                       Patent Number   Inventor   Pub. Date                          U.S. Pat. No. 6,669,222   Barrett et al.   Dec. 30, 2003           U.S. Pat. No. 5,501,480   Ordelman et al.   Mar. 26, 1996           U.S. Pat. No. 4,471,972   Young   Sep. 18, 1984                      
 
      While such devices provide an additional, relatively large front wheel so that irregular terrain may be more easily navigated, such devices are directed towards allowing the wheelchair occupant to propel the wheelchair manually using a chain and sprocket mechanism similar to that of a conventional bicycle. As a result, such devices are limited to a maximum speed at which the occupant can sustain manually, as well as a maximum distance before the occupant tires. Such devices, again, have a limited practical range, albeit over a greater variety of surfaces. A further drawback with many such devices is that they are relatively bulky and are not easily stored when not in use. Detaching such devices from the wheelchair involves the use of tools, with the exception of the &#39;480 patent, which has a relatively complicated wheelchair attachment mechanism.  
      One notable prior art patent is U.S. Pat. No. 5,207,286 to McKelvey on May 4, 1993, which teaches a powered wheelchair attachment device that effectively converts a wheelchair into a powered, tricycle. However, while such a device does allow for long distance and higher-speed travel over a variety of surfaces, since it lifts the smaller front wheels of the wheelchair off of the ground, this device is anything but compact and easy to store. A complicated wheelchair attachment mechanism is included that requires the permanent addition of two cross-bars to the wheelchair.  
      Another notable prior art device is taught in U.S. Pat. No. 3,912,032 to Benz et al. on Oct. 14, 1975, in which a powered attachment with a large front wheel is relatively easily attached to a wheelchair. Again, however, the wheelchair must be significantly modified in order to be attachable to such a device.  
      Therefore, there is clearly a need for a powered wheelchair attachment that can be attached to an existing wheelchair without the need to modify the wheelchair. Further, such a device would be easily removed by the wheelchair user without the need to get out of the wheelchair or obtain help from a third party. Such a needed device would be relatively compact, easy to store, and relatively inexpensive to manufacture. Such a needed device would convert a wheelchair into a three-wheeled powered tricycle capable of traversing irregular terrain at a reasonably high rate of speed for an extended duration, thereby making longer distance trips more practical. The present device accomplishes these objectives and is safe to operate. The present invention is safer than prior designs because of the larger front wheel and steering geometry allows it to travel at higher speeds. Further, a spring mechanism is provided to stabilize the steering.  
     SUMMARY OF THE INVENTION  
      The present device is an improvement for a wheelchair of the type having a pair of generally parallel support bars, a footrest, and a plurality of footrest supporting wheels. The improvement is comprised of generally a crossbar, a center bar, a front wheel post, a front wheel, and a handlebar means. Each end of the crossbar is connected to one of the support bars of the wheelchair with a crossbar mounting means.  
      Preferably the crossbar mounting means uses a ball lock pin for locking to the crossbar. As such, the crossbar may be removed from the wheelchair relatively easily by manually releasing the ball lock pin. Accordingly, it is relatively easy to convert the wheelchair into a powered vehicle, and vice versa, manually without requiring the use of tools.  
      The center bar is fixed at one end thereof proximate to a center point of the crossbar and terminates at the other end thereof at a front wheel post support. The center bar includes a pivoting joint that defines a lower center bar and an upper center bar pivotally interconnected thereby. The pivoting joint is pivotably fixed between an operating position wherein the lower and upper center bars are co-linear, and a non-operating position, wherein the lower and upper center bars are not co-linear. A locking sleeve is slidably retained on the center bar so as to slide over the pivoting joint when the pivoting joint is in the operating position, thereby preventing the pivoting joint from pivoting out of the operating position.  
      The front wheel post is rotationally captured by the front wheel post support. A lower end of the front wheel post terminates in a pair of generally parallel fork posts. The front wheel is axially mounted between the pair of fork posts and includes a rotational bearing around which the wheel may freely rotate. A powered driving means rotationally drives the front wheel and is controlled by a throttle means mounted on the handlebar means.  
      An upper end of the front wheel post terminates in a handlebar support. The handlebar is fixedly attached to the handlebar support of the front wheel post. Brakes may also be included on the handlebar means, as in known in the art.  
      In use, the crossbar mounting means of the improvement is mounted to the support bars of the manual wheelchair. An occupant of the wheelchair may then push forward on the handlebar so as to cause the pivoting joint to pivot such that the lower center bar and the upper center bar become co-aligned, whereby the locking sleeve slides down by gravity over the pivoting joint. The pivoting joint is formed with two hinges pivotally connected. Accordingly, the footrest supporting wheels are raised above a ground surface and the wheelchair may now be driven and steered by the occupant, the combination of which acts as a powered three-wheel vehicle.  
      The present invention is a powered wheelchair attachment that can be attached to an existing manual wheelchair without the need to modify the wheelchair. Further, such a device is easily removed by the wheelchair user without the need to get out of the wheelchair, use tools, or obtain help from a third party. The present device is relatively compact, easy to store, and relatively inexpensive to manufacture. Further, the present invention converts a manual wheelchair into a three-wheeled powered tricycle capable of traversing irregular terrain at a reasonably high rate of speed for an extended duration, thereby making longer distance trips more practical. Other features and advantages of the present invention will become apparent from the following more detailed description, taken in conjunction with the accompanying drawings, which illustrate, by way of example, the principles of the invention.  
    
    
     DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is a side elevational view of the invention as attached to a wheelchair and in a non-operating position;  
       FIG. 2  is a side elevational view of the invention as attached to the wheelchair and in an operating position, elevating footrest supporting wheels above a ground surface;  
       FIG. 3  is a partial perspective view of the invention, illustrating in further detail a crossbar attached at both ends thereof to the wheelchair, and a pivoting joint of a center bar in the non-operating position;  
       FIG. 4  is a partial perspective view of the invention, illustrating in further detail the pivoting joint of the center bar in the operating position, a locking sleeve fixed thereover;  
       FIG. 5  is a partial perspective view of the invention, illustrating in further detail a crossbar mounting means for attaching the crossbar to the wheelchair;  
       FIG. 6  is a partial top plan view of the invention, illustrating lateral slide adjustment means of the crossbar;  
       FIG. 7  is a partial perspective view of a handlebar means of the invention, illustrating a throttle means and a breaking means thereof; and  
       FIG. 8  is a partial side elevational view of a spring means of the invention, taken generally along lines  8 - 8  of  FIG. 2 .  
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       FIG. 1  illustrates an improvement  10  for a wheelchair  20  of the type having a pair of generally parallel support bars  30  ( FIGS. 3 and 4 ), a footrest  40 , and a plurality of footrest supporting wheels  50 . For example, a wheelchair  20  sold under the brand name “Typhoon W.K.-&#39;00” is well-suited for use with the improvement  10  of the present invention.  
      The improvement  10  is comprised of generally a crossbar  60  ( FIG. 3  and  4 ), a center bar  90 , a front wheel post  100  which includes forks  110 , a front wheel  140 , and a handlebar means  160 . Each end  70  of the crossbar  60  is connected to one of the support bars  30  of the wheelchair  20  with a crossbar mounting means  80  ( FIGS. 5 and 6 ). The crossbar mounting means  80  is preferably a split clamp  81  commonly used to fix items to tubular bars ( FIG. 5 ). The split clamp  81  preferred in the present invention comprises an outer clamp  82  and an inner clamp  84  bolted to each other through mounting holes  86  using an Allan-head bolt with a Nylock-type nut. As such, the crossbar  60  may be firmly attached to the support bars  30  so that, even with a strong moment force or vibrational forces applied to the center bar  90  the crossbar mounting means  80  of each end  70  of the crossbar  60  will firmly hold the support bars  30 .  
      Preferably the hole  88  of each inner clamp  84  accepts a ball lock pin (not shown) for locking the clamp  81  to the crossbar  60 . As such, once initially set, the clamp  81  may be removed from the crossbar  60  relatively easily by manually releasing the ball lock pin. Accordingly, it is relatively easy to convert the wheelchair  20  into a powered vehicle, and vice versa manually without requiring the use of tools.  
      The center bar  90  is fixed at one end  95  thereof proximate to a center point  65  of the crossbar  60  and terminates at the other end  98  thereof at a front wheel post support  100 . The center bar  90  includes a first hinge  144  and a second hinge  146 , forming a pivoting joint  190 , best illustrated in  FIG. 3 , that defines a lower center bar  200  and an upper center bar  210  pivotally interconnected thereby. The pivoting joint  190  is pivotably fixed between an operating position A ( FIG. 4 ) wherein the lower and upper center bars  200 , 210  are co-linear, and a non-operating position B ( FIG. 3 ), wherein the lower and upper center bars  200 , 210  are not co-linear. A locking sleeve  220  is included of greater inside diameter than the outer diameter of the center bar  90 , so that the locking sleeve  220  is slidably retained on the center bar  90 . The locking sleeve  220  may be slid over the pivoting joint when the pivoting joint is in the operating position A, whereby the locking sleeve  220  prevents the pivoting joint from pivoting away from the operating position A. A sleeve locking means  230 , such as a pin  142  protruding from the center bar  90  engaging a slot of the locking sleeve  220 , locks the sleeve  220  over the pivoting joint  190 , thereby locking the pivoting joint  190  in the operating position A. To configure the wheelchair  20  and the improvement  20  into the non-operating position B, the sleeve  220  may be disengaged from the pivoting joint  190  such as by rotating it about the center bar  90  and sliding it up towards the front wheel post support  100 , thereby allowing the pivoting joint  190  to pivot into the non-operating position B.  
      Preferably each crossbar mounting means  80  includes a rotational adjustment mechanism  240  and a slide adjustment  260 , such as an inner crossbar  63  telescopically and rotationally engaged with the crossbar  65  ( FIG. 6 ). As such, a rotational locking mechanism  250 , such as a detent pin, may be used to rotationally and slidably fix each inner crossbar  63  with respect to the outer crossbar  65 . In this way, a variety of wheelchair types can be easily adapted with the improvement  10 , as the crossbar  65  may accommodate varying distances between the support bars  30 , often referred to as seat rails.  
      The front wheel post  100  is rotationally captured by the front wheel forks  110 , as is common with bicycles of the prior art. A lower end  112  of the front wheel post  110  terminates in a pair of generally parallel fork posts  120 . An upper end  114  of the front wheel post  110  terminates in a handlebar support  130 . Preferably a first spring mount  370  is fixed proximate to the front wheel post support  100  on a lower side  380  of the crossbar  90 , and the front wheel post  110  includes a second spring mount  390  fixed to the lower end thereof, such that a spring  400  may be interconnected between the first and second spring mounts  380 , 390  ( FIG. 8 ). As such, the spring  400  urges the wheel  140  into coplanar alignment with the longitudinal axis of the center bar  90  so that that wheelchair  20  and the improvement  10  maintain a generally straight default course when driven. Thus, if the user momentarily loses control, the spring mechanism will stabilize the chair, maintaining the center of gravity.  
      The front wheel  140  is axially mounted between the pair of fork posts  120  and includes a rotational bearing  150  around which the wheel  140  may freely rotate. A power source  270 , such as an electric battery  280  electrically connected through a throttle  300  to an electric motor  290  in the wheel  140 , rotationally drives the front wheel  140  in a forward direction. The electric motor  290  is mechanically interconnected with the front wheel  140  such that rotation of the electric motor  290  causes forward rotation of the wheel  140 . The throttle  300  is preferably an electric current regulator  310  attached to the handlebar  160  proximate to a handgrip  320  thereof ( FIG. 7 ).  
      The handlebar  160  is attached to the handlebar support  130  of the front wheel post  110 , as is commonly known in the art of bicycles and the like. The electric battery  280  is preferably attached to the handlebar  160  so as to not block the visibility of the occupant, but so as to be readily accessible for connecting recharging cables or the like thereto. Preferably the battery  280  is a 36V DC cell, or three 12V DC cells arranged in series. It is has been found that such a batter  280  is capable of powering a 600 Watt DC brushed electric motor so as to enable the wheelchair  20  and the improvement  10  to achieve in excess of 16 miles-per-hour for a distance in excess of twenty miles.  
      A breaking means  300  may be included, such as a caliper  340  mounted around the front wheel  140  ( FIG. 2 ). The caliper  340  is mechanically connected, such as through a cable  345  to a hand lever  350  ( FIG. 7 ) mounted proximate the hand grip  320  of the handlebar means  160 . When the hand grip  320  is actuated, the cable  345  causes the caliper  340  to squeeze a portion  360  of the front wheel  140  therebetween to inhibit rotation of the front wheel  140  ( FIG. 2 ).  
      In use, the crossbar mounting means  80  of the improvement  10  is mounted to the support bars  30  of the wheelchair  20 . The lateral slide adjustment mechanism  260  are adjusted and locked so that crossbar  60  is firmly mounted between the support bars  30 . An occupant of the wheelchair  20  (not shown), sitting therein, may then push forward on the handlebar means  160  so as to cause the pivoting joint  190  to pivot such that the lower center bar  200  and the upper center bar  210  become co-aligned, whereby the locking sleeve  220  slides down by gravity over the pivoting joint  190 . Accordingly, the footrest supporting wheels  50  are raised above a ground surface  180  ( FIG. 2 ) and the wheelchair  20  may now be driven and steered by the occupant, the combination of which acts as a powered three-wheel vehicle.  
      To disengage the wheelchair  20  from the improvement  10 , the locking sleeve  220  is rotated and pushed forward, such that the pivoting joint  190  assumes the non-operating position B ( FIG. 1 ). The ball lock pins of the crossbar  60  are then manually pulled, freeing the crossbar  60  from the crossbar mounting mechanism  80 , and the crossbar  60  may be lowered to the ground  180 . As the pivoting joint  190  only pivots in one direction, around a horizontal left-to-right axis (not shown), the improvement  10  will maintain itself upright on the ground  180  even when not attached to the wheelchair  20 . As such, the improvement  10 , by itself, is easy to handle and store. The wheelchair  20 , once disengaged from the improvement  10 , may be used traditionally such as indoors or in close spaces where use with the improvement is not practical or desired.  
      While a particular form of the invention has been illustrated and described, it will be apparent that various modifications can be made without departing from the spirit and scope of the invention. For example, the materials used for the cross-bar  60  and the center bar  90 , or the handlebar  160 , may be changed to any suitable rigid material other than the preferred titanium alloy. Likewise, the particular nature of the crossbar mounting mechanism  80  may be altered to any suitable mounting means known now or in the future. Accordingly, it is not intended that the invention be limited, except as by the appended claims.