Abstract:
A suspension method and apparatus using a mount, a shock absorber and a moment arm to mitigate stresses and impacts to wheelchair bound individuals. A moment arm attaches to the axle and frame of a wheelchair. A shock absorber supplies suspension between the moment arm and the frame via a mount attached to the frame.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    There are presently almost four million individuals in the United States that spend all day in a wheelchair. In that regard, high-level quadriplegics and other individuals with similar functional ability generally also use a manual wheelchair. A common type of manual wheel chair is a “tilt-in-space” chair. A tilt-in-space wheelchair generally provides a change in position for clients who cannot independently shift their body weight. When an individual is unable to independently shift their weight or change positions while seated in an upright position they are at a very high risk for skin breakdown and sitting tolerance is comprised due to this inability to redistribute pressure. A tilt-in-space chair provides a means for weight shifts and position changes. A tilt-in-space chair reduces the risk of skin breakdown by redistributing pressure from the pelvis to the back. A tilt-in-space provides a safe and easy way for a caregiver to provide a weight shift for the end user. 
         [0002]    While sitting in the upright position, gravity pushes down on the body. If muscle strength or overall endurance is compromised, clients will be unable to maintain proper upright posture, which can lead to postural deviations such as a posterior pelvic tilt, thoracic kyphosis, and lateral lean. 
         [0003]    Manual chairs may be attendant propelled. An attendant propelled chair is one that requires an attendant to propel the chair due to the limitations of the person in the chair. A chair may also be one that is propelled by the person in the chair. Many tilt-in-space chairs are attendant propelled. Such self-propulsion may be performed by the person using the wheels of the chair to move the chair forward or backward. Also, a self-propelled chair may be propelled by an electromechanical means operated by the person in the chair. A tilt-in-space chair may also be referred to as a rotation-in-space chair. 
       SUMMARY OF THE INVENTION 
       [0004]    An embodiment of the invention may therefore comprise a method for providing suspension to a wheelchair, the method comprising attaching a mount to a frame support of the wheelchair, attaching a shock absorber to the mount, placing at least one moment arm on an axle of the wheelchair, attaching the at least one moment arm to the frame support of the wheelchair, and attaching the shock absorber to the at least one moment arm. 
         [0005]    An embodiment of the invention may further comprise a suspension for a wheelchair, the suspension comprising a mount, wherein the mount is attachable to a frame support of the wheelchair, a shock absorber, wherein the shock absorber is attachable to the mount, and at least one moment arm, wherein the at least one moment arm is attachable to an axle of the wheelchair, is attachable to the frame support, and is attachable to the shock absorber. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]      FIG. 1  shows a wheelchair frame and a suspension. 
           [0007]      FIG. 2  shows a wheelchair wheel and a suspension. 
           [0008]      FIG. 3  shows a suspension with a frame support and an axle. 
           [0009]      FIG. 4  shows an exploded view of a suspension. 
           [0010]      FIG. 5  shows an alternate mount. 
           [0011]      FIG. 6  shows a downward mount spring connection. 
           [0012]      FIG. 7  shows a suspension with a frame support and an axle. 
       
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
       [0013]    Manual wheelchair designs generally mount its rear wheels on an axle. Further, attendant propelled, tilt-in-space wheelchairs used in support of spinal cord, other injuries and predisposition genetic disabilities generally have at least one axle, or partial axles provided for individual wheels. For example, a Quickie Iris model wheelchair and the Invacare Solara model wheelchair are chairs that have at least one axle, or partial axles provided for individual wheels. 
         [0014]    Wheelchair designs that have a rear axle wheel mount may further include a rail-like rolling frame that is positioned substantially perpendicularly to the axle. The rolling frame may include a number of passages or openings positioned at regular distances along its length. Such passages may be sized to allow a bolt to pass through, thereby allowing for nuts and bolts attachments. 
         [0015]    Many manual wheelchair designs may not include a suspension. Individuals in wheelchairs that lack suspension may experience pain or discomfort when traversing across uneven surfaces. A suspension on a manual wheelchair may provide life enhancing opportunities. 
         [0016]      FIG. 1  shows a wheelchair frame and a suspension. In the wheelchair and suspension shown in  FIG. 1 , only a portion of the wheelchair and suspension is shown.  FIG. 1  shows a rear wheel  110  connected to an axle  120 . A wheelchair frame  130  connects to frame supports  150 . A front wheel  160  connects to the wheelchair frame support  150 . A suspension  170  is shown connected to the frame supports  150  and the axle  120 . Those skilled in the art will understand that only a portion of the wheelchair is shown. A seat, for instance, is not shown in  FIG. 1 , as well as the other rear wheel. A rotational, or tilt, mechanism  180  is shown connecting the wheelchair frame to the frame supports. The rotational, or tilt, mechanism  180  allows the wheelchair frame  130  to rotate and provide physical comfort to a client. 
         [0017]      FIG. 2  shows a wheelchair wheel and a suspension.  FIG. 2  is a close up view of the suspension  170 , wheel  110  and axle  120  of  FIG. 1 .  FIG. 2  shows a wheel  210 , an axle  220 , a frame support  250  and a suspension  270 . The suspension is comprised of a mount  273 , a pair of moment arms  272  and a shock absorber with spring  271 . The mount  273  connects to the frame support  250 . The mount  273  is shown connected to the frame support with a pair of nuts and bolts  274 . The shock absorber with spring  271  is shown connected to a lower connector portion of the mount  273 . The shock absorber with spring  271  connects to the moment arm  272 . The moment arm  272  connects to the frame support  250  and to the axle  220 . As forces act on the wheel  210  during movement of the wheelchair, the moment arm  272  will rotate about the connection to the frame support  250 . The shock absorber with spring  271  provides resistive force but allows the wheelchair to move with reduces jarring movements. Those skilled in the art will understand that the pair of moment arms  272  may be a singular moment arm. 
         [0018]      FIG. 3  shows a suspension with a frame support and an axle. In  FIG. 3 , extraneous components of the wheelchair, such as the wheel and frame, are not shown to remove visual obstructions and provide a clear view of the components of a wheelchair suspension. A mount  373  is connected to a frame support  350 . The mount  373  connects to a shock absorber with spring  371 , which connects to at least one moment arm  372 . The moment arm  372  may be one of two or more moment arms.  FIG. 3  shows a pair of moment arms  372 . The shock absorber with spring in  FIG. 3  may be any type of shock absorber with spring that provides suspension effects. The spring in the shock absorber and spring assembly may be adjusted to accommodate different weights of the occupants of the chair. The spring component can be an extension spring. The spring may be a torsion spring. The spring may be a tapered spring. Those skilled in the art will understand the various types of springs, and shock absorbers, and connection arrangements that may be used to provide suspension effects to a wheelchair. 
         [0019]    As shown in  FIG. 3 , the shock absorber with spring  371  may be attached to the two moment arms  372  that have been positioned on opposite sides of the frame support  350 . As discussed, it is understood that a single moment arm  372  may be utilized in the invention. The moment arms  372  may be attached to the frame support  350 , as well as attached to the axle  320  of the wheelchair. The moment arm  372  has a first opening  377  configured to encircle around the rear axle  320  of the wheelchair, a second opening for a bolts and nuts attachment to the frame support and a third opening for bolts and nuts attachment to the shock absorber with spring  371 . The moment arm  372  may have an alternate configuration for attaching to the axle. For instance, the moment arm  372  may have an opening that does not fully encircle the axle  320  but which allows the moment arm, during installation, to be placed over the axle without removing the axle and then is held in place firmly once the moment arm  372  is attached to the frame support  373  and the shock absorber with spring  371 . 
         [0020]      FIG. 4  shows an exploded view of a suspension. The suspension  400  comprises a shock absorber with spring  471 , a pair of moment arms  472 , and a mount  473 . The moment arms  472  connect to an axle (not shown in  FIG. 4 ) and to the shock absorber with spring  471 . The moment arm additionally connects to a frame support (not shown in  FIG. 4 ). The shock absorber with spring  471  also connects to the mount  473 . The mount  473  shown in  FIG. 4  comprises a pair of plates. Each of the plates will attach to the frame support. As shown, the mounts  473  comprise the plates where each of the plates has a plurality of holes which are configured to align with holes in the frame support and which enables a bolt and nut to attach the mount  473  to the frame support. As shown in  FIG. 4 , the mount attaches to the frame support on two opposing sides of the frame support. A nut and bolt configuration  475  may be used to affix the mount  473  to a frame support. Two moment arms  472  are shown in  FIG. 4 . It is understood that one moment arm  472  may be used to provide connection to a frame support and to an axle. The two moment arms  472  connect to a frame support with a nut and bolt  475  arrangement. The two moment arms  472  each have a hole configured to align with holes in a frame support and which enable the bolt and nut  475  to attach the moment arms  472  to the frame support. The shock absorber with spring  471  attaches to the mount  473  utilizing a bolt and nut arrangement  475 . A hole toward one end of the shock absorber with spring  471  aligns with holes in the mount  473  to allow the bolt and nut to connect the spring  471  to the mount  473 . A second hole in the shock absorber with spring  471  that is located toward the other end of the shock absorber with spring  471  allows a bolt and nut arrangement  475  to connect the shock absorber with spring  471  to the moment arms  472 . The second hole aligns with holes in the moments arms  472  to allow the shock absorber with spring  471  to connect to the moment arms  472 . 
         [0021]    The bolt and shock absorber with spring arrangements  475  shown in  FIG. 4  may comprise a washer or other element to allow easy connections and security to any resulting connection. Other arrangements may also be utilized. For instance, a pin type connection that allows a pin to slide into the holes and then be secured on one end with a connector that disallows the pin to be removed from the hole. In two dimensions, a pin connection restrains two translation degrees of freedom but does not restrain rotation. Those skilled in the art will understand various other methods of connection the shock absorber with spring to the moment arms and mounts, and the moment arms and mount to a frame support. The invention herein described is not limited to any particular means of connecting the shock absorber with spring, mounts or moment arms. 
         [0022]      FIG. 5  shows an alternate mount. The mount  500  may be shaped to fit on three sides of a frame support. The mount could have a first side  510 , a second side  520  and an underside  530 . The term underside is not meant to indicate that the side is required to be under anything. The mount may also be shaped to fit on  2  sides of a frame support. The first side  510  and the second side  520  are opposite each other and the underside  530  could provide an additional—connection between the first side  510  and the second side  520 . The first side  510  and the second side  520  may have openings that align with each other and that will align with holes or openings in a frame support that allow for bolts and nuts attachments. 
         [0023]      FIG. 6  shows a downward mounted shock absorber with spring connection. The mount of  FIG. 5  may further include a component portion  600  that protrudes downwardly from the mount  500 . The portion component  600  may have an opening  610  that is designed to align with an opening of a shock absorber with spring (not shown in  FIG. 6 ). A bolts and nuts attachment may be used to attach a shock absorber with spring at one end to the portion component  600  using the aligned openings.  FIG. 6  shows two component portions  600  suspended from the underside  530  of the mount  500 . A single component portion  610  may be used and the side of the shock absorber with spring that attaches to the mount  500  may be adapted to attach to the single component portion  610 . 
         [0024]      FIG. 7  shows a suspension with a frame support and an axle. In  FIG. 7 , extraneous components of the wheelchair, such as the wheel and frame, are not shown to remove visual obstructions and provide a clear view of the components of a wheelchair suspension. A mount  773  is connected to a frame support  750 . The mount  773  connects to a shock absorber with spring  771 , which connects to at least one moment arm  772 . The moment arm  772  may be one of two or more moment arms.  FIG. 7  shows a pair of moment arms  772 . The shock absorber with spring in  FIG. 7  may be any type of shock absorber with spring that provides suspension effects. The spring in the shock absorber  771  and spring assembly may be adjusted to accommodate different weights of the occupants of the chair. The spring component can be an extension spring, or any other type of spring or shock absorber. Those skilled in the art will understand the various types of springs, and shock absorbers, and connection arrangements that may be used to provide suspension effects to a wheelchair. 
         [0025]    As shown in  FIG. 7 , the shock absorber with spring  771  may be attached to the two moment arms  772  that have been positioned on opposite sides of the frame support  750 . As discussed, it is understood that a single moment arm  772  may be utilized in the invention. The moment arms  772  may be attached to the frame support  750 , as well as attached to the axle  720  of the wheelchair. The moment arm  772  has a first opening  777  configured to encircle around the rear axle  720  of the wheelchair, a second opening for a bolts and nuts attachment to the frame support and a third opening for bolts and nuts attachment to the shock absorber with spring  771 . 
         [0026]    In  FIG. 7 , the axle has a stop  780 . The moment arm  772  has a corresponding stop accepting cutout  785 . The first opening  777  will fit over the axle  720  wherein the cutout will fit the stop. The stop may be referred to as a stop spindle, an anti-rotational device or protrusion. The stop, with the cutout fitted over the stop, prevents the moment arm  772  from rotating in relation to the axle when force is applied. Although the stop in  FIG. 7  is shown as a protrusion from the axle, it is understood that other forms of stops may be used. For instance, the axle may comprise a notch wherein the moment arm has a protrusion from the first opening that fits into the notch. The stop of the axle is shown as a rectangular protrusion. It is understood that the stop may be shaped in any manner that allows stoppage of rotation of the moment arm. For instance, the stop may be dome shaped or triangular. Those skilled in the art will understand the different shapes that the stop may assume. 
         [0027]    The presently described suspension is described in regard to a particular type of axle and frame organization of a wheel chair. For example, in  FIG. 3 , as well as other figures showing an axle, the axle is above the frame support. It is understood that in certain wheelchairs the axle may reside below the frame support. As such, the suspension of the invention would be likewise flipped and the suspension would work equally well for the wheelchair. The mounts, shock absorber with spring, and moment arms described herein may be modified to accommodate different sizes, shapes, and configurations of the various wheelchair components or corresponding components. 
         [0028]    The foregoing description of the invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed, and other modifications and variations may be possible in light of the above teachings. The embodiment was chosen and described in order to best explain the principles of the invention and its practical application to thereby enable others skilled in the art to best utilize the invention in various embodiments and various modifications as are suited to the particular use contemplated. It is intended that the appended claims be construed to include other alternative embodiments of the invention except insofar as limited by the prior art.