Patent Publication Number: US-7900945-B1

Title: All-terrain wheelchair

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     The present application claims the priority benefit of U.S. provisional patent application Ser. No. 60/983,787, filed Oct. 30, 2007, entitled “ALL-TERRAIN WHEELCHAIR” of the same named inventor. The entire contents of that prior application are incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to wheelchairs. More particularly, the present invention relates to wheelchairs suitable for use over a range of terrain conditions. 
     2. Description of the Prior Art 
     Individuals constrained to move in wheelchairs often run into obstacles in getting to locations of interest that may be inconvenient, but not restrictive, to others. While certain statutory obligations have eased accessibility restrictions in regard to buildings, walkways and the like, there remain many locations, particularly related to the outdoors, where individuals continue to experience impediments. In fact, there are a wide variety of terrains and conditions that are typically prohibitive to users of conventional wheelchairs and power chairs—especially outdoor environments and elements e.g. forest floors, hilly and rough terrain, ice, snow, mud, and sand. In general, soft terrain can be particularly difficult to manage. 
     In addition to the limitations of movement associated with outdoor activities, there remain manmade obstacles that either bar access or render the process of access excessively cumbersome. For example, there remain daily manmade obstacles such as curbs and high thresholds. Further, for those individuals without substantial upper body strength and without powered chairs, an array of imposing terrain conditions restrict access to areas of interest. Those without power chairs must move their chairs by placing hand to wheel to cause wheel rotation. Over long trips that can be physically exhausting. Over messy terrain, such as snow, puddles and mud, it can be very messy. 
     Therefore, what is needed is a wheelchair suitable for use by a broad range of individuals over a wide range of terrain conditions including, but not limited to, outdoor natural terrain. 
     SUMMARY OF THE INVENTION 
     The present invention overcomes the limitations associated with existing wheelchairs. In particular, the present invention is an all-terrain wheelchair that is a geared device including push-bar structures to enable individuals of varied physical strength to move the chair along a wide range of terrains, including soft terrain. The push-bars allow the user to establish mobility without hand to wheel interaction. The unique design propels the user forward with a forward motion of the push-bars while pulling back on the push-bars engages a braking system. Turning is achieved with a forward motion on one push-bar and a backward motion on the other push-bar. 
     The all-terrain chair of the present invention offers the user a multi-speed geared advantage over traditional wheelchairs. Shifting into lower gears for snow, mud, and sand, gives the user the freedom to go where they have not been able to go with traditional wheelchairs. Simply shifting into higher gears allows for movement on pavement and other hard surfaces. The push-bars are removable and may therefore be stored so that the chair may be moved using conventional hand-to-wheel pushing. 
     The all-terrain chair allows the user to manage a wide variety of terrains and conditions that are typically prohibitive to users of conventional wheelchairs and power chairs—especially outdoor environments and elements e.g. forest floors, hilly and rough terrain, ice, snow, mud, and sand. Further, it can be used to overcome many daily obstacles such as curbs and high thresholds. It is advantageous for individuals less upper body and arm strength and function. As a result, it provides for greater, independent participation in outdoor activities such as hiking, hunting, fishing, camping, backpacking, and outdoor photography. 
     These and other advantages will become apparent upon review of the following detailed description and the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a right side view of the all-terrain wheelchair of the present invention. 
         FIG. 2  is a top view looking down on the wheelchair with the seat and back removed. 
         FIG. 3  is a front view of the wheelchair. 
         FIG. 4  is a side view of a portion of the right side of the wheelchair. 
         FIG. 5  is a side view of the frame that is the inside of the right side frame and the outside of the left side frame of the wheelchair. 
         FIG. 6  is a side view of a portion of the right side of the wheelchair showing the front right wheel. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT OF THE INVENTION 
     An all-terrain wheelchair  10  of the present invention is shown in  FIGS. 1-6 . The wheelchair  10  includes right and left front wheels  12  and  14 , right and left rear wheels  16  and  18 , a primary structural frame  20 , a back rest  22 , a seat  24  and a foot rest  26 . The wheelchair  10  also includes a removable right push bar  28  and a removable left push bar  30 . The front wheels  12  and  14  are pneumatic or other suitable tires and are sized smaller than the rear wheels  16  and  18 . The rear wheels  16  and  18  may also be pneumatic or other suitable tires and make be mounted on spoked rims. The wheelchair  10  is configured to allow the user to generate forward movement using the push bars  28  and  30  rather than through direct hand contact with the rear wheels  16  and  18 . The push bars  28  and  30  are coupled to the rear wheels  16  and  18  through independent sprocket-and-chain arrangements configured to enable the user to gain leverage suitable for moving the wheelchair  10  across uneven terrain and through a range of ground surface conditions including mud and snow, for example. 
     The primary structural frame  20  includes a first primary frame bar  32 , a second primary frame bar  34 , a first primary cross bar  36  and a second primary cross bar  38 . The components of the primary structural frame  20  are preferably fabricated of a high strength, lightweight, corrosion resistant material. Coated aluminum or stainless steel tubing is suitable for this purpose, although the primary structural frame  20  is not limited to fabrication of such materials. The first primary frame bar  32  and the second primary frame bar  34  are curved from a horizontal orientation to a vertical orientation from back to front of the wheelchair  10 . The horizontal portions of the pair of primary frame bars  32 / 34  are configured to support the seat  24  thereon. The first primary cross bar  36  and the second primary cross bar  38  are connected to the first primary frame bar  32  and the second primary frame bar  34  by stanchions  40  and are further joined together by accessory tube  41 . All components of the primary structural frame  20  may be joined together permanently, such as by welding. Alternatively, some or all of those components may be removably connected together. 
     The first primary cross bar  36  and the second primary cross bar  38  are also coupled to a right rear wheel frame  42  and a left rear wheel frame  44 . That coupling may be a permanent connection, such as by welding, or it may be a removable coupling. The right rear wheel frame  42  and the left rear wheel frame  44  have a general wishbone configuration but they are not specifically required to be so arranged. The right rear wheel frame  42  includes an inside plate  46  and an outside plate  48 . The left rear wheel frame  44  includes an inside plate  50  and an outside plate  52 . In the embodiment of the wheelchair  10  described herein, the inside plate  46  of the right rear wheel frame  42  has a design equivalent to that of the outside plate  52  of the left rear wheel frame  44 , and the outside plate  48  of the right rear wheel frame  42  has a design equivalent to that of the inside plate  50  of the left rear wheel frame  44 . The invention is not limited thereto. The inside plate  46  of the right rear wheel frame  42  and the inside plate  50  of the left rear wheel frame  44  are both coupled to the first primary cross bar  36  and the second primary cross bar  38 , either permanently or removably. 
     The right rear wheel frame  42  includes a primary attachment bar  54  that joins the inside plate  46  and the outside plate  48  together. The primary attachment bar  54  of the right rear wheel frame  42  is joined to right front sprocket bar  56 , which extends substantially perpendicular from a bottom end of the primary attachment bar  54 . A right front wheel coupling bar  58  extends downwardly at an angle from a top end of the primary attachment bar  54 . The right front wheel coupling bar  58  terminates at and is joined to a right front wheel fork bearing tube  60 . The right front wheel fork bearing tube  60  includes a port for receiving and releasably retaining therein a fork bolt  62  arranged to removably and rotatably join the primary attachment bar  54  to a right front wheel fork  64 . The right front wheel fork  64  is arranged to receive and retain the right front wheel  12  in a manner that allows its pivotal movement upon turning of the wheelchair  10  in a left or right direction. The right front wheel fork  64  completes the coupling of the right front wheel  12  to the primary structural frame  20  of the wheelchair  10  through the right rear wheel frame  42 . 
     The left rear wheel frame  44  includes a primary attachment bar  66  that joins the inside plate  50  and the outside plate  52  together. The primary attachment bar  66  of the left rear wheel frame  44  is joined to left front sprocket bar  68 , which extends substantially perpendicular from a bottom end of the primary attachment bar  66 . A left front wheel coupling bar  70  extends downwardly at an angle from a top end of the primary attachment bar  66 . The left front wheel coupling bar  70  terminates at and is joined to a left front wheel fork bearing tube  72 . The left front wheel fork bearing tube  72  includes a port for receiving and releasably retaining therein a fork bolt  74  arranged to removably and rotatably join the primary attachment bar  66  to a left front wheel fork  76 . The left front wheel fork  76  is arranged to receive and retain the left front wheel  14  in a manner that allows its pivotal movement upon turning of the wheelchair  10  in a left or right direction. The left front wheel fork  76  completes the coupling of the left front wheel  14  to the primary structural frame  20  of the wheelchair  10 . 
     The right rear wheel frame  42  is arranged to rotatably retain the right rear wheel  16  between the inside plate  46  and the outside plate  48 . The inside plate  46  includes a first right wheel hub slot  78  and the outside plate  48  includes a second right wheel hub slot  80 . Hub slots  78  and  80  are sized and arranged to enable insertion therein of a hub of the right rear wheel  16 , in a configuration resembling that of the rear frame of a bicycle. Similarly, the left rear wheel frame  44  is arranged to rotatably retain the left rear wheel  18  between the inside plate  50  and the outside plate  52 . The inside plate  50  includes a first left wheel hub slot  82  and the outside plate  52  includes a second left wheel hub slot  84 . Hub slots  82  and  84  are sized and arranged to enable insertion therein of a hub of the left rear wheel  18 , again, in a configuration resembling that of the rear frame of a bicycle. 
     The outside plate  48  of the right rear wheel frame  42  also includes a right chain slot  86 . Similarly, the inside plate  50  of the left rear wheel frame  44  includes a left chain slot  88 . The wheelchair  10  is configured so that the right push bar  28  may be actuated manually to move the right side wheels and the left push bar  30  may be actuated manually to move the left side wheels, so that the two sides may be moved in unison for straight ahead movement or they may be moved independent of one another to enable left turning (moving the right side only) or right turning (moving the left side only). Specifically, the user pushes the right push bar  28  forward and pulls the left push bar  30  backward to cause movement of the right side of the wheelchair  10  while the left side remains braked, causing leftward movement of the wheelchair  10 . Similarly, the user pushes the left push bar  30  forward and pulls the right push bar  28  backward to cause movement of the left side of the wheelchair  10  while the right side remains braked, causing rightward movement of the wheelchair  10 . 
     The flexibility of movement is achieved by having separate left and right actuation mechanisms. The right side mechanism includes the right push bar  28  coupled to right front sprocket bar  56 , right front sprocket  90  coupled to the right push bar  28  through right front sprocket bar  56 , right chain  92 , and right internal hub gear  94  coupled to the right front sprocket  90  by right chain  92 . The right push bar  28  is a shaft insertable into a tube. The right front sprocket bar  56  is a tube that includes a bearing therein to which the shaft of the right push bar  28  is removably connected. The right chain  92  passes from the outside of outside plate  48  of right rear wheel frame  42  to the inside thereof through right chain slot  86 . The right rear hub gear  94  forms part of the hub of the right rear wheel  16  and is preferably a multi-gear but is not limited thereto. The right rear hub gear  94  also includes an associated drum brake. The position of the right rear hub gear  94 , and therefore the gearing or leverage provided by the movement of the right push bar  28  is modified by right gear adjustment cable  98 . The right gear adjustment cable  98  is modified by right gear shifter  100 , which may be a rotatable index shifter, as shown. In operation, the user pushes the right push bar  28  forward, which causes forward rotation of the right front sprocket  90 , corresponding forward rotation of the right chain  92  and the right rear hub gear  94 , culminating in forward rotation of the right rear wheel  16 . 
     The left side mechanism functions in a similar manner. It includes the left push bar  30  coupled to left front sprocket bar  68 , left front sprocket  102  coupled to the left push bar  30  through left front sprocket bar  68 , left chain  104 , and left internal hub gear  106  coupled to the left front sprocket  102  by left chain  104 . The left push bar  30  is a shaft insertable into a tube. The left front sprocket bar  68  is a tube that includes a bearing therein to which the shaft of the left push bar  30  is removably connected. The left chain  104  passes from the inside of inside plate  52  of left rear wheel frame  44  to the outside thereof through left chain slot  88 . The left rear hub gear  106  forms part of the hub of the left rear wheel  18  and is preferably a multi-geared hub but is not limited thereto. The left rear hub gear  106  also includes an associated drum brake. The position of the left rear hub gear, and therefore the gearing or leverage provided by the movement of the left push bar  30  is modified by a left gear adjustment cable (not shown). The left gear adjustment cable is modified by a left gear shifter (not shown), which may be a rotatable index shifter, as shown. In operation, the user pushes the left push bar  30  forward, which causes forward rotation of the left front sprocket  102 , corresponding forward rotation of the left chain  104  and the left rear hub gear  106 , culminating in forward rotation of the left rear wheel  18 . It is to be understood that the left gear adjustment cable and the left gear shifter are the same as the right gear adjustment cable  98  and the right gear shifter  100 , but are simply not shown to aid in viewing of other components of the wheelchair  10 . 
     With continuing reference to  FIGS. 2 and 3 , the wheelchair  10  further includes a pair of brake rods associated with the respective ones of the right rear wheel  12  and the left rear wheel  14 . Specifically, the right side of the wheelchair  10  includes a right brake rod  108  that is coupled to right rear hub  110  of the right rear wheel  16 . The right brake rod  108  includes brake lever arm  112  that is coupled to the right push bar  28 . When pulling back on the right push bar  28 , the user actuates the brake lever arm  112 , causing the right brake rod  108  to halt forward movement of right rear hub gear  94  and, therefore, forward movement of right rear wheel  16 . Similarly, the left side of the wheelchair  10  includes a left brake rod  114  that is coupled to left rear hub  116  of the left rear wheel  18 . The left brake rod  114  includes a brake lever arm (not shown) that is coupled to the left push bar  30  through left rocker arm  118 . The right side of the wheelchair  10  has a similar rocker arm arrangement that is omitted only for the purpose of enabling the viewing of other components of the wheelchair  10 . When pulling back on the left push bar  30 , the user actuates the left side brake lever arm, causing the left brake rod  114  to halt forward movement of left rear hub gear  106  and, therefore, forward movement of left rear wheel  18 . 
     The all-terrain wheelchair  10  of the present invention is propelled with two removable push bars, one located on each side of the wheelchair seat. The push bars are insertable into tubes that are in turn attached to shafts that are attached to sprockets. Each shaft passes through a tube that terminates with a bearing at the end of the tube. A chain extends from each sprocket through a slot in a wheel frame to an internal multi-gear hub with associated drum brake, which hub is preferably located behind the seat. Each push bar works independently of the other, thereby allowing the user to steer the wheelchair by braking on one hub and propelling on the other. Gears are changed by speed shifters mounted on tubes that are each mounted on left and right extension tubes. Pneumatic or other suitable tires are mounted on rims that are mounted to left and right front forks. Multi-speed hubs are mounted to the rims. The all-terrain wheelchair  10  may be formed with large steel tubing for frames, all joints are preferably welded, the bearings and gearing are preferably sealed, and the plate steel back and seat are preferably welded. As noted, it is be understood that the invention may be made in other ways with other materials and other means of attaching, enclosing and the like. 
     In operation, a user maneuvers the all-terrain wheelchair  10  as follows. Pulling back on the push bars  28 / 30  pivots brake levers that, in turn, pull the brake rods so as to effect engagement of the brake. Pushing forward on the push bars  28 / 30  engages the chain on the sprocket at a selectable gear ratio dependent upon the underlying terrain and the physical capability of the user. The all-terrain wheelchair  10  includes wheelchair foot rests and a back rest that may be adjusted in modifiable increments. The wheelchair frame height may be standard or selectable, and the width of the wheelchair  10  may be adjusted through shortening or lengthening attached cross bars. The all-terrain wheelchair  10  additionally optionally includes one or more accessory receivers, such as gun or fishing rod receptacles. 
     Advantageous features of the invention include, but may not be limited to the following, all of which distinguish the present invention from commercially available existing manual wheelchairs. First, a substantial mechanical advantage over a range of terrains and activities is provided with the conveniently controllable gearing arrangement and push bars described. Second, gears. Second, the multi-gear rear hubs can be easily engaged while at a standstill—no movement required as with a derailer system. Third, the removable push bars  28 / 30 , either or both of which may be deployed and independently operated, can be used as the drive system as an alternative to conventional hand-to-wheel propulsion. Fourth, the wheelchair  10  allows the user to push forward on the push bars  28 / 30  to drive the wheelchair  10  forward, and to pull back on those same push bars  28 / 30  to engage the brake drums. 
     These features provide, but are not limited to, the following useful advantages for the user. First, the wheelchair  10  provides stability in that it is significantly less likely to tip over than conventional chairs, particularly having a low center of gravity and desirable axle placement through the arrangement of the primary frame  20 . Second, the rear wheels  16 / 18  may be cambered and configured with large, wide, aggressively treaded pneumatic tires, and the front wheels  12  and  14  may be configured with caster tires to aid in movement over varied terrains. Third, the wheelchair  10  may include a stability bar as part of the primary frame  20 , which stability bar is attachable to the rear portion of the wheelchair  10  to minimize unintended rearward tipping. 
     One or more example embodiments to help illustrate the invention have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the invention. Accordingly, other embodiments are within the scope of the claims appended hereto.