Abstract:
The present invention provides an economical, universal wheelchair conversion kit which offers two, hand-powered, variable-resistive, drive mechanisms for the main wheels of a wheelchair which can be retrofitted to existing wheelchairs and that provide the operator of the vehicle means of easy mobility, independent brakes for safety and maneuverability, and the resistive means for exercising the upper body musculature and the cardiovascular systems while using the chair in either a mobile or stationary configuration. The present invention enables the elevation of the wheelchair rear wheels such that the wheelchair is dedicated to an exercise function. In all, the present invention provides a comprehensive solution to the mobility and immobility health related problems of many wheelchair bound persons.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to wheelchairs and, more specifically, to wheelchairs employing mechanisms that increase the mechanical advantage to reduce the effort of propelling the vehicle while conversely providing the means of increasing that effort to allow the operator to use the wheelchair as an exercise machine for maintaining physical fitness. The present invention, the Easy Glide Chair Kit, provides a wheelchair so equipped: with two separate hand-operated brakes for each wheel, two tensioning bolts for varying the operating resistance of each main wheel, two extendable legs for immobilizing the chair for exercise operation only and two hand-operated drive mechanisms for each main wheel which allow the operator to propel the chair forward or backward, stop and turn, using differential input. 
     The drive mechanism consists of a hand-operated, generally vertically-oriented lever connected to a reversible ratchet assembly that in turn drives a speed-reducing gear assembly consisting of a smaller ratchet-driven ratchet/gear cluster driving the larger gear which is rigidly mounted to and axially aligned with each main wheel. Additionally, adjustable resistive means are provided for each side for increasing or decreasing the force required to operate the handle to provide the operator with means for selectively exercising the upper muscular and cardiovascular systems. Another health related feature of the present invention is its ability to convert a wheelchair to use purely as an exercise machine, by providing a pair of extendable legs or jacks mounted on either side at the rear portion of the chair for lifting the main wheels off the ground, thereby allowing them to rotate freely. In all, the present invention provides a more comprehensive solution, compared to prior art, to the mobility and immobility health related problems of wheelchair bound persons. 
     2. Description of the Prior Art 
     There are other hand operated drive systems designed for wheelchairs. Typical of these is U.S. Pat. No. 4,460,190 issued to Spiess on Jul. 17, 1984. 
     Another patent was issued to Herron on Dec. 24, 1985 as U.S. Pat. No. 4,560,181. Yet another U.S. Pat. No. 4,758,013 was issued to Agrillo on Jul. 19, 1988 and still yet another was issued on Apr. 28, 1998 to Weaver as U.S. Pat. No. 5,743,544. 
     U.S. Pat. No. 4,460,190 
     Inventor: Erick M. Spiess 
     Issued: Jul. 17, 1984 
     A three wheeled wheelchair wherein two of the wheels are leading wheels with the single wheel being a trailing wheel. The wheelchair is propelled through the use of a chain drive assembly which is to be manually operated through the use of a handle assembly. Adjacent the handle assembly is a seat which is to support the occupant of the wheelchair. The seat is cushionly supported by a shock absorber assembly. The handle assembly is attached to a steering mechanism which, through lateral movement of the handle assembly, causes the leading wheels to be turned in respect to the frame of the wheelchair. A separate turning wheel assembly is to be manually movable to an extended position to cause the trailing wheel to be spaced from the supportive surface thereby permitting three hundred and sixty degree turning of the wheelchair about a single point. 
     U.S. Pat. No. 4,560,181 
     Inventor: Matthew A. Herron 
     Issued: Dec. 24, 1985 
     A wheelchair and drive mechanism powered by reciprocating operation of a drive lever. The drive mechanism provides a continuously variable gear ratio allowing wheelchair operation at varying speeds and on differing inclines; and is readily fitted to a standard wheelchair by a drive-associated bayonet mount. A drive mechanism ratchet wheel includes an upper and lower radial crank secured for rotation thereabout by an axle. Each crank includes a pawl assembly that engages with circumferential ratchet wheel teeth to transfer drive energy supplied to the radial cranks from connecting arms to the ratchet wheel. The connecting arms are coupled to a reciprocating lever arm and operate in concert with the pawls to alternately engage with and transfer energy to the ratchet wheel, or disengage therefrom. While one connecting arm and associated pawl is transferring energy to the ratchet wheel, the other connecting arm is disengaging an associated pawl from the ratchet wheel. Energy is transferred during both a forward and rearward stroke of the lever arm to effect efficient wheelchair and drive operation. 
     U.S. Pat. No. 4,758,013 
     Inventor: Timothy P. Agrillo 
     Issued: Jul. 19, 1988 
     A hand crank powered wheelchair with forward, coast, reverse, and braking capability. The wheelchair has a left and right hand crank. Each hand crank is used to independently control the two rear wheels. A clutch and brake is contained in the hub of each rear wheel. The clutch drives wheel forward when hand crank is rotated forward and allows wheel to coast when hand crank stops rotation. A reverse enable lever selects brake or reverse mode. When in brake mode minimal energy applied to crank in the reverse direction will slow or stop rear wheel. When in reverse mode, brake acts as clutch, allowing reverse rotation of hand crank to drive rear wheel backward. The drive may include a gear shift mechanism. Drives of the invention may be applied to other wheeled vehicles such as delivery tricycles. 
     U.S. Pat. No. 5.743,544 
     Inventor: Michael J. Weaver 
     Issued: Apr. 28, 1998 
     An improved wheelchair and hub assembly is described that interposes reduction gearing between the handring or rotatable hand wheel and the drive wheel of the assembly. This gearing provides some mechanical advantage to users who may lack sufficient strength to propel themselves in a conventional wheelchair, especially in a home environment. A single speed assembly is described which is operated conventionally by rotating handrings either forward or rearward to produce a corresponding rotation of the drive wheel but, unlike conventional wheels, a complete revolution of the handring results in only a partial revolution of the drive wheel. In the hub of the assembly is a wheel locking mechanism which enables the wheel to be easily and positively locked for the safety of the user, preventing rotation of the wheel in either direction. Additionally, a ratcheting mechanism is incorporated into the hub design which can be engaged to allow forward rotation but prevent rearward rotation of the drive wheels. 
     While these wheelchair hand operated drive systems may be suitable for the purposes for which they were designed, they would not be as suitable for the purposes of the present invention, as hereinafter described. 
     SUMMARY OF THE PRESENT INVENTION 
     A primary object of the present invention is to provide a universal conversion kit for a wheelchair with independent, hand-powered, lever-operated, speed reducing, drive mechanisms for each wheel whereby the operator thereof may be able to easily propel the wheelchair forward, backward, as well as turn using differential input. 
     Another object of the present invention is to provide a universal wheelchair conversion kit with independent, hand-powered, speed reducing, drive mechanisms for each wheel that also provides independently operating hand brakes for safety and maneuverability. 
     Another object of the present invention is to provide a universal wheelchair conversion kit with independent, hand-powered, speed reducing, drive mechanisms for each wheel, independent hand brakes, and means for varying the input drive effort to allow the operator to use the wheelchair as a mobile exercise machine to improve and maintain upper body muscular and cardiovascular systems. 
     A still further object of the present invention is to provide a universal wheelchair conversion kit with independent, hand-powered, speed reducing, drive mechanisms for each wheel, with independent hand brakes, means for operating as a mobile exercise machine, having further means for converting the mobile exercising capability to a stationary configuration. 
     Additional objects of the present invention will appear as the description proceeds. 
     The present invention overcomes the shortcomings of the prior art by providing an economical, universal wheelchair conversion kit which offers two, hand-powered, variable-resistive, drive mechanisms for the main wheels of a wheelchair which can be retrofitted to existing wheelchairs and that provide the operator of the vehicle means of easy mobility, independent brakes for safety and maneuverability, and the resistive means for exercising the upper body musculature and the cardiovascular systems while using the chair in either a mobile or stationary configuration. In all, the present invention provides a more comprehensive solution, compared to prior art, to the mobility and immobility health related problems of wheelchair bound persons. 
     The foregoing and other objects and advantages will appear from the description to follow. In the description reference is made to the accompanying drawings, which form a part hereof, and in which is shown by way of illustration specific embodiments in which the invention may be practiced. These embodiments will be described in sufficient detail to enable those skilled in the art to practice the invention, and it is to be understood that other embodiments may be utilized and that structural changes may be made without departing from the scope of the invention. In the accompanying drawings, like reference characters designate the same or similar parts throughout the several views. 
     The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of the present invention is best defined by the appended claims. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In order that the invention may be more fully understood, it will now be described, by way of example, with reference to the accompanying drawings in which: 
     FIG. 1 is a perspective view of a wheelchair of the prior art which has been designed to reduce the amount of exertion needed to operate the chair. Although there are times when this is desirable it would be more advantageous if the operator were permitted to selectively adjust the amount of resistance as desired, as well as, being able to use the chair as a stationary exercising device. 
     FIG. 2 is a perspective view of the present invention installed on the wheelchair shown in FIG.  1 . Shown is a housing attached to the wheelchair frame, and a drive gear attached to an axle on the housing. The axle has a ratchet mechanism attached thereon, the ratchet mechanism engaging the drive gear, the ratchet mechanism having a gear shaft with slidably engageable members. The drive gear engages a large gear on the rear wheel. Also shown is a junction box having controls for engaging a lifting mechanism for selectively raising the rear wheels from an engaging position to a non-engaging position, whereby the wheelchair can be operated as a stationary exercise device. 
     FIG. 3 is a left side view of the present invention installed on a wheelchair. Shown is a partial view of the rear wheel gear engaging the ratcheting system drive gear, whereby the wheelchair can be selectively propelled by means of a length adjustable handle, or as illustrated, the rear of the wheelchair can be raised by attachable legs whereby the wheelchair can be used as a stationary exercise device. Also shown is the hand-operated brake for stopping the rotation of the left wheelchair rear wheel. 
     FIG. 4 is a right side view of the present invention installed on a wheelchair. Shown is a partial view of the rear wheel gear engaging the gear ratcheting system drive gear, whereby the wheelchair can be selectively propelled by means of a length adjustable handle, or as illustrated, the rear of the wheelchair can be manually, hydraulically, or electromechanically raised, whereby the wheelchair can be used as a stationary exercise device. Also shown is the hand-operated brake for stopping the rotation of the right wheelchair rear wheel. 
     FIG. 5 is a rear view of the present invention installed on the wheelchair. Shown are the rear wheels of the wheelchair, the same having been raised and supported to a predetermined position on the jacks, whereby the wheelchair can be operated as a stationary exercise device. 
     FIG. 6 is a front view of the present invention installed on the wheelchair. Shown are extendable and retractable handles having resistive motion means for increasing the amount of energy expended by the operator in propelling the wheelchair from one location to another, or in turning the rear wheels, should the lifting mechanisms be engaged and the resistive motion mechanism further engaged. Also shown are the hand-operated brakes for stopping the rotation of the wheelchair rear wheels. 
     FIG. 7 is a top plan view of the present invention installed on the wheelchair, further depicting the alignment of the drive gears with the rear wheel gears, and the positioning of the handles and the brake handles. 
     FIG. 8 is an enlarged partial view of the wheelchair&#39;s left rear wheel, showing hand brake interaction with the wheelchair frame and left rear wheel, providing means for selectively engaging the drive wheel in a motive or stationary position. 
     FIG. 9 is an enlarged partial view of the brake member from the opposite side as shown in FIG. 8, revealing the brake spring which biases the brake member to its disengaged position. 
     FIG. 10 is an enlarged partial view of the brake member mounted in a position that is reversed from the position shown in FIG.  8 . 
     FIG. 11 is an enlarged front plan view of the drive mechanism and tensioning member used to increase the force necessary for the operator to rotate the wheelchair rear wheels, whether the wheelchair is being used as a stationary exercise device or a means for transportation. Also shown is the knuckle, which is used as an alternate means for ratcheting the handle. Also shown are the axle, u-bolts for attachment to wheelchair, housing, handle, and grip. knuckle, ratchet mechanism, drive gear, and rear wheel gear. 
    
    
     DESCRIPTION OF THE REFERENCED NUMERALS 
     Turning now descriptively to the drawings, in which similar reference characters denote similar elements throughout the several views, the Figures illustrate the universal conversion kit for human powered wheelchairs of the present invention. With regard to the reference numerals used, the following numbering is used throughout the various drawing figures. 
       10  universal conversion kit for human powered vehicles of the present invention 
       12  prior art wheelchair 
       14  wheelchair frame 
       16  wheelchair seat 
       18  wheelchair rear wheels 
       20  wheelchair front wheels 
       22  wheelchair axle 
       24  handring 
       30  rear wheel gears 
       32  attachment members for attaching rear wheel gear to wheelchair rear wheel 
       34  housings 
       36  U-bolts 
       38  axles 
       40  grease fittings 
       42  ratchet mechanisms 
       44  handles 
       46  handle grips 
       48  knuckles 
       50  drive gears 
       52  handle first portion 
       54  handle second portion 
       56  opposing spaced hole pairs in handle second portion 
       58  pair of holes in handle first portion 
       60  pin 
       70  tension members 
       80  legs 
       82  non-skid caps 
       90  hydraulic jacks 
       92  junction box for jack controls 
       94  manual pumps 
       96  handheld control 
       100  brake members 
       102  brake member first portion 
       104  brake member grip 
       106  brake member second portion 
       108  brake pad 
       109  brake spring 
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Turning now descriptively to the drawings, in which similar reference characters denote similar elements throughout the several views, FIGS. 1 through 11 illustrate the universal conversion kit for human powered vehicles of the present invention indicated generally by the numeral  10 . 
     A typical wheelchair  12  is depicted in FIG. 1 without the benefit of the present invention. It includes a frame  14 , a seat  16 , two large rear wheels  18  attached to the frame  18 , and two pivoting smaller wheels  20 , also attached to the frame  14 . The rear wheels  18  have an axle  22  attached to the frame  14 . The wheelchair  12  is typically propelled by grasping and turning a handring  24 , which is attached to each rear wheel  18 . 
     FIGS. 2-7 depict a rear wheel gear  30  that is rigidly attached to each of the wheelchair rear wheels  18  by attachment members  32 , or by attachment (not shown) to the wheelchair axle  22 . A housing  34  is attached on each side of the frame  14  by U-bolts  36  as more closely shown in FIGS. 2 and 9. Each housing  34  supports an axle  38 , the axle  38  having a grease fitting  40  for servicing. 
     Attached to each such axle  38  is a reversible ratchet mechanism  42 . To each such ratchet mechanism  42  is attached a handle  44 , with each handle  44  having a grip  46  and a knuckle  48 . Also attached to each axle  38  is a drive gear  50  that is positioned to mesh with the corresponding rear wheel gear  30 . The handle  44  works the ratchet mechanism  42  such that manipulation of the handle  44  selectably rotates the drive gear  50  in a first direction, for forward motion of the wheelchair  12 , and a second direction, for rearward motion of the wheelchair  12 . The occupant has the choice of grasping either the grip  46  or the knuckle  48 , for purposes of such manipulation. 
     Each handle  44  has a first portion  52  and a second portion  54 , the second portion  54  telescoping within the first portion  52 , the second portion  54  having at least two pair of opposing spaced hole pairs  56 , and the first portion  52  having at least one pair of opposing spaced hole pairs  58 , that is alignable with one of such spaced hole pairs  56 , such that a pin  60  or other member, may be inserted through both portions  52 , 54 , as depicted in FIG.  11 . This allows the length of each handle  44  to be independently adjusted. The handle adjustability is also present in other embodiments (not shown) where the second handle portion  54  screws into the first handle portion  52 , where the second handle portion  54  has a spring loaded member which aligns with and protrudes through a hole in the first handle portion  52 , where the foregoing adjustability components and functions of the first and second handle portions  52 , 54  are reversed, and other mechanisms in accordance with the present invention, and as determined by the intended end use for the overall handle  44  assembly, as will occur to those of skill in the art upon review of the present disclosure. 
     The adjustability of the handle  44  acts to increase the force required from the operator to work the ratchet mechanism  42  and rotate the drive gear  50 , in that the handle  44  acts as a moment arm, and a shorter moment arm requires a higher load to be applied in the pushing or pulling of the handle  44 . Similarly, use of the knuckle  48  always results in a shorter effective moment arm when compared to the grip  46 , regardless of the length to which the handle  44  is set. 
     Resistance to rotation of the drive gear  50  is also provided by the tension members  70  depicted in FIGS.  2 , 5 - 7 , and  9 . Each tension member  70  is positioned on the housing  34  such that, when adjusted, the tension member  70  bears upon the axle  38 , although a similar result could be achieved by bringing such a member to bear on the drive gear  50 . In this embodiment, the tension member  70  is a bolt, which is threadably mounted on each housing  34  such that rotation of the bolt forces it to bear upon the axle  38 . The amount of resistance to rotation of the drive gear  50  is variable, depending upon the extent to which the tension member  70  is brought to bear against the axle  38 . 
     The handrings  24  can be relocated to a position adjacent the rear wheel gears  30 , reestablishing the original means of propulsion as a continuously available alternate to the present invention. 
     FIG. 3 depicts a pair of legs  80  which can be attached to the wheelchair frame  14 , the legs lifting the wheelchair  12  such that the rear wheels  18  are disengaged from the floor or other ground surface. This, and other embodiments of the present invention that provide such rear wheel  18  disengagement, completely dedicates the wheelchair  12  to an exercise function, allowing the occupant to engage in exercises for upper muscular and cardiovascular systems. The addition of non-skid caps  82  provides a stabilizing effect by resisting movement on the front wheels  20 . As shown in FIG. 3, typical wheelchair frame  12  structure readily receives the legs  80 . In the absence of the particular wheelchair frame  12  structure shown in FIG. 3, common fastening devices (not shown), e.g. clamps, grips, can be provided as part of the legs  80  for attachment of the legs  80  to various wheelchair frame  12 , such as the frame sides  84 . 
     FIGS. 4-6 depict representative jack mechanisms  90  for lifting the rear wheels  18 , including jacks  90  that are raised and lowered hydraulically (shown), electromechanically (not shown), and manually (not shown). FIG. 2 depicts the junction box  92  that holds two manual pumps  94  for hydraulically raising and lowering the jacks  90 . The associated hydraulic lines  94  are also shown. When the occupant chooses to dedicate the wheelchair  12  to the exercise function, he or she manipulates the manual pumps  94  causing the jacks  90  to be raised, and the rear wheels  18  elevated. The tension members  70  are then set to provide the amount of rotational resistance that is required for the goals of the exercise session to be achieved. Once the exercise session is completed, the operator again manipulates the manual pumps  94  causing the jacks  90  to be lowered, and the rear wheels  18  are returned to the surface. After readjusting the tension member  70 , the operator is able to resume the normal motive operations of the wheelchair  12 . 
     The junction box  92  depicted in FIG. 2, is also available to contain controls for the analogous operation of raising and lowering electromechanical jacks. In either case, the controls  90  and their electromechanical counterparts do not necessarily require an attached junction box, since other non-frame  14  mounted, handheld controls (not shown) would also suffice. 
     A single jack (not shown) having a wide base can also be utilized. 
     The unmodified wheelchair  12  is typically stopped by grasping the handrings  24 . In embodiments of the present invention in which the handrings  24  are not repositioned adjacent the respective rear wheel gears  30 , the brake function is provided by a pair of brake members  100 , as shown in FIGS. 2-10. Each of the brake members  100  are pivotally attached to the wheelchair frame  14 , and each has a first portion  102  that has a grip  104 , and a second portion  106  that has an attached brake pad  108 . The brake member  100  is movable from a first position to a second position, the brake pad  108  being brought to bear on the rear wheel  18  in the second position. In the embodiment shown in FIGS. 3-4, the brake member first portion  102  is pushed to the second position. A spring  109  can be provided to bias the brake member  100  to the first position. It is also feasible to reverse the pivotal attachment of the brake member  100  to the wheelchair frame  14 , and adjust the angle between the brake member first portion  102  and second portion  106 , such that the brake member first portion  102  is pulled to the second position, as shown in FIG.  10 . This alternate embodiment allows gravity to assist in the bias to the first position, due to the weight of the brake member first portion  102 . 
     It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of methods differing from the type described above. 
     While certain novel features of this invention have been shown and described, and are pointed out in the annexed claims, it is not intended to be limited to the details above, since it will be understood that various omissions, modifications, substitutions and changes in the forms and details of the device illustrated and in its operation can be made by those skilled in the art without departing in any way from the spirit of the present invention. 
     Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention.