Abstract:
A wheelchair has a base and a front anti-tip wheel assembly that retracts when impacted by an obstruction encountered by the wheelchair, but is maintained in an extended position when the wheelchair undergoes forward pitch. Also, the wheelchair has a swingaway light mounting system that includes a mounting receiver and a swinging light bracket mounting one or more lights. The swinging light bracket is mounted for rotation when impacted by an obstruction encountered by the wheelchair.

Description:
RELATED APPLICATIONS  
       [0001]     This application claims priority from U.S. Provisional Patent Application Ser. No. 60/620,942, filed Oct. 21, 2004, and entitled WHEELCHAIR REVERSIBLE BETWEEN FRONT WHEEL DRIVE AND REAR WHEEL DRIVE. This application also claims priority from U.S. Provisional Patent Application Ser. No. 60/621,431, filed Oct. 22, 2004, and entitled WHEELCHAIR WITH TELESCOPIC ANTI-TIP WHEEL. 
     
    
     TECHNICAL FIELD  
       [0002]     This invention relates to wheelchairs.  
       BACKGROUND OF THE INVENTION  
       [0003]     Wheelchairs frequently are designed with a pair of front wheels and a pair of rear wheels. Power wheelchairs are usually one of three varieties, front wheel drive, rear wheel drive, and mid wheel drive. Wheelchairs are often equipped with anti-tip wheel wheels to prevent the wheelchair from tipping over. Some wheelchairs are equipped with running lights and turn signals.  
       SUMMARY OF THE INVENTION  
       [0004]     According to this invention there is provided a wheelchair having a base and a front anti-tip wheel assembly that retracts when impacted by an obstruction encountered by the wheelchair, but is maintained in an extended position when the wheelchair undergoes forward pitch.  
         [0005]     According to this invention there is also provided a wheelchair having a base and a front anti-tip wheel assembly that includes an anti-tip wheel mounted in an extended forward position during normal operation and subject to retraction in a rearward direction along a longitudinal axis when impacted by an obstruction encountered by the wheelchair. The anti-tip wheel is mounted for easy retraction when the anti-tip wheel is impacted by a force along the longitudinal axis, but is maintained in the extended position when the anti-tip wheel is impacted by a force at an angle to the longitudinal axis.  
         [0006]     According to this invention there is also provided a wheelchair having a swingaway light mounting system that includes a mounting receiver and a swinging light bracket mounting one or more lights. The swinging light bracket is mounted for rotation when impacted by an obstruction encountered by the wheelchair.  
         [0007]     According to this invention there is also provided a wheelchair having a swingaway light mounting system that includes a mounting receiver and a swinging light bracket mounting one or more lights, with the swinging light bracket being mounted for rotation when impacted by an obstruction encountered by the wheelchair. The swinging light bracket is mounted so that it can be rotated in either a forward or rearward direction, and the light mounting system is configured to provide a resistive force urging the swinging light bracket to return to a neutral position when the swinging light bracket is rotated in either the forward or the rearward direction. The mounting system includes a hub mounted within the receiver, with the receiver having a cam profile at an upper end, and the hub having a cam profile at a lower end. The hub is urged into engagement with the mounting receiver by a spring, wherein rotation of the swinging light bracket compresses the spring, thereby urging the swinging light bracket to return to a neutral position.  
         [0008]     Various objects and advantages of this invention will become apparent to those skilled in the art from the following detailed description of the preferred embodiment, when read in light of the accompanying drawings. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]      FIG. 1  is a schematic view in elevation of a wheelchair in a front wheel drive mode.  
         [0010]      FIG. 1A  is a schematic view in elevation of the base of the wheelchair.  
         [0011]      FIG. 2  is a schematic perspective view of the underside of the wheelchair of  FIG. 1 .  
         [0012]      FIG. 3  is a perspective view of the anti-tip wheel assembly in an extended position.  
         [0013]      FIG. 4  is a perspective view of the anti-tip wheel assembly in a retracted position.  
         [0014]      FIG. 5  is an exploded view of the anti-tip wheel assembly in perspective.  
         [0015]      FIG. 6  is perspective view of a wheelchair light and turn indicator swingaway mounting system.  
         [0016]      FIG. 7  is a plan view of the swingaway mounting system with the swingaway light in a neutral position.  
         [0017]      FIG. 8  is a plan view of the swingaway mounting system with the swingaway light moved after an impact from the front.  
         [0018]      FIG. 9  is a plan view of the swingaway mounting system with the swingaway light moved after an impact from the rear.  
         [0019]      FIG. 10  is an exploded schematic view of the swingaway mounting system.  
         [0020]      FIG. 11  is a perspective view similar to that of  FIG. 6 , but from a different angle.  
         [0021]      FIG. 12  is a bottom perspective view of the swingaway mounting system.  
         [0022]      FIG. 13  is a side elevation view of the swingaway mounting system.  
         [0023]      FIG. 14  is a cross-sectional view in elevation of the swingaway mounting system, taken along line  14 - 14  of  FIG. 13 . 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0024]     As illustrated in  FIGS. 1, 1A  and  2 , the wheelchair, indicated generally at  10 , includes a base  12  and seat assembly  14 . The seat assembly includes a seat  16 , a seat back  18 , and optional leg rests  20 . The base  12  includes a chassis  22 , drive wheels  24  and caster wheels  26 . A drive wheel swing arm, indicated generally at  30 , includes a gear box  32  that is fixed to the swing arm  30  by bolting or any other suitable fastening mechanism. Mounted to the gearbox is a drive motor  34 . The drive wheel  24  is mounted to the gear box  32 . The swing arm  30  enables the drive wheel  24  to move up and down relative to the chassis  22 , pivoting at pivot point  36 . The wheelchair is optionally provided with removable shrouds, such as front shroud  28 A, drive wheel shroud  28 B, side rail shrouds  28 C,  
         [0025]     An anti-tip wheel assembly  40  is mounted to the swing arm  30 , projecting in a forward direction. As further shown in  FIGS. 3-5 , the anti-tip wheel assembly  40  includes an outer or rearward tube  42  configured to telescopingly receive an inner or forward tube  44 . The anti-tip wheel  46  is mounted at the forward end of the inner tube  44 . The outer and inner tubes  42  and  44  can be of any shape or material. Preferably they are made of tubular aluminum members. Although the anti-tip wheel assembly shown has the forward tube  42  being telescopically received within the rearward tube  44 , it is to be understood that this can be reversed, with the forward tube receiving the rearward tube.  
         [0026]     The outer and inner tubes  42  and  44  can be of a size and shape such that as long as there is no canting, or sideways or vertical component of force applied to the tubes, the inner tube  44  will slide easily within the outer tube  42 . If there is a somewhat sideways or vertical component to the force applied to the inner tube  44 , however, the inner tube  44  will not slide easily within the outer tube  42 . Any force other than a linear or axial force applied to the inner tube  44  in the direction of the longitudinal axis  48  of the anti-tip wheel assembly will produce a sideways or vertical component to the force, and hence will cause the inner tube  44  to slide less easily or not at all within the outer tube  42 . The amount of resistance to sliding produced by a sideways or vertical component to the force applied to the inner tube  44  may depend on the relative proportion of the force in the longitudinal direction to the component of sideways or vertical force. The amount of resistance may also depend on the coefficient of friction of the inner surface of the outer tube  42  and the coefficient of friction of the outer surface of the inner tube  44 .  
         [0027]     A retaining mechanism, such as a slot  50  and a retaining pin  51 , can be used to limit the relative positions of the outer and inner tubes  42  and  44 . The pin is shown connected to the inner tube  44 , although the pin can be on the outer tube  42 . As the inner tube  44  slides within the outer tube  42 , the pin  51  can travel the length of the slot  50 . Any means suitable for limiting the relative positions of the tubes  42  and  44  to a specified range can be used. The anti-tip wheel assembly  40  can include a rear bracket  52  and a mid bracket  54  to attach the anti-tip wheel assembly  40  to the swing arm  30 . More specifically, the outer tube  42  is attached to the swing arm  30 . As shown in  FIG. 5 , a spring  56  is positioned within the inner and outer tubes  42  and  44 . The spring  56  is attached to the pin  51  or to the inner tube  44 . The rearward end of the spring  56  is attached to the rearward end of the outer tube  42 .  
         [0028]     In operation, when the rear wheel drive wheelchair  10  encounters an obstacle, such as a curb, the impact of the anti-tip wheel  46  against the curb will cause the inner tube  44  to retract within the outer tube  42 , against the force of the spring  56 . In the event that the wheelchair  10  is experiencing a condition of forward pitch, the swing arm  30  will pivot relative to the wheelchair chassis  22 , and the axis  48  of the anti-tip wheel assembly  40  becomes at an acute angle to the ground. A non-axial force is applied to the inner tube  44 , and the inner tube is prevented from sliding rearwardly into the outer tube  42 . During normal driving on flat ground, the inner tube  44  is fully extended due to the spring pressure. The anti-tip wheel  46  is positioned forward of the drive wheel  24  so that when the wheelchair stops suddenly and pitched forward, the anti-tip wheel  46  contacts the ground and prevents the wheelchair from tipping over. Accordingly, the anti-tip wheel assembly  40  can effectively act as an anti-tip device, preventing or at least inhibiting the wheelchair from tipping over forwardly.  
         [0029]     In another aspect of the invention, the wheelchair is provided with a wheelchair light and turn indicator light system attached to the wheelchair  10  with a swingaway mounting system. As shown in  FIGS. 6, 11 ,  13  and  14 , the light system  110  includes a swing away bracket assembly  114 . A bracket  116  is fixed to the seat frame or any other desirable part of the wheelchair  110 . An adjustable bracket  118  is connected to the fixed bracket  116 . A mounting receiver  120  has an attachment fixture  122  mating with the fixture  124  on the adjustable bracket  118 . A hub  128  is positioned concentrically within the receiver  120 . A swinging light r cap  133  is mounted on top of the hub  128  and the receiver  120 . The swinging light cap has a swing light bracket  130  for holding the head light  132  and the turn indicator  134 . Any type of light can be attached.  
         [0030]     As shown in  FIG. 10 , the hub  128  has a cam profile  136  at its lower end. The hub  128  is urged into engagement with the mounting receiver  120  by the spring  140 , nut  142  and bolt  144 . The mounting receiver  120  also has a cam profile. The hub  128  and the receiver  120  are held together as an assembly by the bolt  144  and locking nut  142 . The spring  140  is always in some compression. This allows the swing light bracket  130  to maintain a neutral position perpendicular to the adjustable bracket  118 , as shown in  FIG. 7 . If the light assembly receives an impact from the front, as shown in  FIG. 8 , the swinging light bracket  130  rotates and at the same time the hub  128  rises as it follows the cam profile. This compresses the spring  140  further, providing a resistive force that urges the swinging light bracket  130  back into a neutral position. Once the obstruction is clear, the compression in the spring  140  forces the swinging light bracket  130  to return to the center or neutral position. The reverse happens for an impact from the rear, as shown in  FIG. 9 . As shown in  FIG. 12 , the mounting reciver  120  has a dovetail wedge groove  150 , and this connects with the dovetail strip  152  on the bracket fixture  124  of the bracket  118 . It is to be understood that any attachment system can be used.  
         [0031]     The principle and mode of operation of this invention have been described in its preferred embodiments. However, it should be noted that this invention may be practiced otherwise than as specifically illustrated and described without departing from its scope.