Patent Publication Number: US-6217052-B1

Title: Notched axle bracket support for a wheelchair

Description:
RELATED APPLICATIONS 
     The present invention is related to the inventions of the following U.S. patent applications Ser. No. 09/332,823, entitled ANGLED AXLE BRACKET FOR A WHEELCHAIR, filed on Jun. 14, 1999; and Design application Ser. No. 29/106,352, entitled A REAR WHEEL MOUNTING CLAMP FOR A WHEELCHAIR, filed on Jun. 14, 1999, and issued on May 2, 2000 as U.S. Pat. No. Des. 423,993. 
    
    
     TECHNICAL FIELD 
     This invention relates in general to wheelchairs, and more specifically to wheelchairs having drive wheels mounted for rotation. More particularly, this invention relates to mechanisms for mounting wheelchair drive wheel axles to wheelchair frames. 
     BACKGROUND OF THE INVENTION 
     Wheelchairs are well known forms of transportation that increase the mobility of the physically impaired. Wheelchairs are typically relatively small, single-person conveyances that generally comprise a seat supported by a frame which, in turn, is supported by two opposed drive wheels and two front casters. 
     The wheelchair occupant&#39;s center of gravity is generally positioned close to the drive wheels to permit the wheelchair occupant to maneuver the wheelchair with greater ease. The wheelchair occupant&#39;s center of gravity may be shifted in a number of ways. The drive wheels may be cambered so that the distance between the drive wheels at ground level is greater than the distance between the drive wheels at the seat. In addition to cambering the drive wheels, adjusting the position of the drive wheels relative to the wheelchair frame may also shift the wheelchair occupant&#39;s center of gravity. For example, the drive wheels may be moved forward or backward, or may be raised or lowered, relative to the wheelchair frame to shift the wheelchair occupant&#39;s center of gravity. 
     Adjusting the wheelchair seat relative to the wheelchair frame may also shift the center of gravity of the wheelchair occupant. In addition to shifting the center of gravity of the wheelchair occupant, adjusting the wheelchair seat may improve the orientation of the arms and hands of the wheelchair occupant relative to the drive wheels. Improving the orientation of the arms and hands of the wheelchair occupant relative to the drive wheels enables the occupant of the wheelchair to propel the wheelchair with greater comfort and increased efficiency. Adjusting the wheelchair seat periodically also reduces the risk of tissue trauma suffered by the wheelchair occupant by reducing the constant pressure between the wheelchair occupant&#39;s skin and the wheelchair, and particularly, the wheelchair seat. 
     Adjusting the position of the drive wheels relative to the wheelchair frame can be accomplished in several ways. Typically, the drive wheels are mounted for rotation on an axle, with the axle being insertable into an axle tube that is mounted on the wheelchair frame. Adjustment between the relative positions of the drive wheels and the wheelchair frame can be accomplished by moving the axle tube relative to the frame. Another means of adjusting the position of the drive wheels relative to the wheelchair frame is to move the portions of the frame housing the axle tube relative to the remainder of the wheelchair frame. It is known to have an axle bracket that can be mounted to a frame member in either a forward or rearward direction to provide longitudinal adjustability of the axle with respect to the frame. 
     It would be advantageous if there could be developed a simplified assembly for enabling easy adjustment of the position of wheelchair drive wheels with respect to the wheelchair frame. Such a mechanism should be easy to assemble and disassemble for rapid adjustment of the wheelchair drive wheels, and should provide a wide margin of adjustment. Further, the mechanism should be simple in construction for long service life, easy installation and low manufacturing cost. 
     SUMMARY OF THE INVENTION 
     The above objects as well as other objects not specifically enumerated are achieved by an axle support system for supporting an axle for a wheelchair drive wheel. The axle support system includes an elongated wheelchair frame member. A portion of the surface of the elongated frame member is a frame contact surface, and a portion of the surface of the elongated frame member is an indexing section defined by a series of grooves separated by lands. A bracket is mounted for movement along the elongated wheelchair frame member. The bracket has an orifice for receiving a wheelchair drive wheel axle, a bracket contact surface, and a connector for securing the bracket to the elongated frame member. The frame contact surface of the elongated frame member is aligned with the bracket contact surface, thereby preventing rotation of the bracket with respect to the elongated frame member. The connector is engagable with a selected groove of the series of grooves of the elongated frame member to fix the position of the bracket along the elongated frame member. 
     In another embodiment of the invention, there is provided a wheelchair comprising side frames for supporting a seat, drive wheels and caster wheels on which the side frames are mounted, and an axle support system for supporting axles for the drive wheels. The axle support system includes an elongated wheelchair frame member. A portion of the surface of the elongated frame member is a frame contact surface, and a portion of the surface of the elongated frame member is an indexing section defined by a series of grooves separated by lands. A bracket is mounted for movement along the elongated wheelchair frame member. The bracket has an orifice for receiving a wheelchair drive wheel axle, a bracket contact surface, and a connector for securing the bracket to the elongated frame member. The frame contact surface of the elongated frame member is aligned with the bracket contact surface, thereby preventing rotation of the bracket with respect to the elongated frame member. The connector is engagable with a selected groove of the series of grooves of the elongated frame member to fix the position of the bracket along the elongated frame member. 
     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 
     FIG. 1 is a schematic view in elevation of a wheelchair including the axle bracket of the invention. 
     FIG. 2 is an enlarged schematic view in elevation of a portion of the wheelchair, showing the axle bracket of the invention. 
     FIG. 3 is a schematic elevational view of the axle bracket, and a cross-sectional view of the elongated frame member, taken along line  3 — 3  of FIG.  2 . 
     FIGS. 4-7 are schematic elevational views illustrating various arrangements of the axle bracket with respect to the elongated frame member. 
     FIG. 8 is an enlarged schematic view in elevation similar to FIG. 2, illustrating an alternate embodiment of the axle bracket of the invention installed on a vertical elongated frame member. 
     FIG. 9 is a schematic elevational view similar to FIG. 3, but showing an alternate embodiment in which the axle bracket is offset laterally for increased flexibility. 
     FIG. 10 is a schematic elevational view similar to FIG. 3, but showing yet another embodiment of the axle bracket, with a the frame coupling comprising a single flange. 
     FIG. 11 is a schematic cross-sectional view in elevation of the elongated frame member taken along line  11 — 11  in FIG. 2, partially showing the pin. 
     FIG. 12 is a schematic elevational view of an alternate embodiment of the axle bracket elongated frame member, similar to that of FIG. 3, but showing non-planar contact surfaces between the axle bracket and the elongated frame member. 
    
    
     DETAILED DESCRIPTION AND PREFERRED EMBODIMENTS OF THE INVENTION 
     As shown in FIG. 1, the wheelchair is indicated generally at  10 . The wheelchair is generally comprised of a pair of side frames  12 , a seat  14  supported by the side frames, a rear drive wheel  16  and a front caster wheel  18 . The side frames  12  are typically comprised of light weight tubular members joined together by fasteners or by welding. As shown, the side frame  12  is comprised of two portions, a rear side frame assembly  20  and a front side frame assembly  22 . The front side frame assembly  22  includes a generally horizontal upper side rail  24  and a generally horizontal lower side rail  26 . These are connected together by forward vertical strut  28  and rear vertical strut  30 . It is to be understood that the front side frame assembly can be configured in many different styles and still perform the function of providing support for the wheelchair seat  14  and the wheelchair user. 
     The rear side frame assembly  20  is comprised of a generally vertical rear member  36  and a generally horizontal elongated frame member  40 . The vertical rear member  36  can be provided with an upwardly extending seat back frame to support a seat back, not shown. An axle mounting bracket  44  is slidably mounted onto the elongated frame member  40  so that the axle mounting bracket can be moved longitudinally along the elongated frame member  40  into various positions, as indicated by directional arrows  46 . The axle mounting bracket  44  includes an axle orifice  48  for receiving the drive wheel axle or axle sleeve, neither of which are shown in FIG.  1 . It can be seen that moving the axle mounting bracket  44  longitudinally along the elongated frame member  40  enables the drive wheel to be positioned forwardly or rearwardly in several different positions. This ability to position the drive wheel forwardly or rearwardly with respect to the elongated frame member  44 , and hence with respect to the entire side frame  12 , offers the wheelchair user a great deal of flexibility in moving the center of gravity of the wheelchair forward and rearward. This flexibility is advantageous because it allows the wheelchair user to change the relative position of the drive wheel with respect to the user&#39;s arms and hands. Also, the ability to change the center of gravity alters the share of the weight applied to each of the four wheels, and this enables the wheelchair user to modify the dynamic motion characteristics of the wheelchair. For example, moving the center of gravity rearward reduces the weight applied to the front caster wheels  18 , thereby changing the maneuverability character of the wheelchair. 
     As shown in FIGS. 2 and 3, the axle bracket is generally comprised of a frame coupling  50 , which is attached to the elongated frame member  40 , and an axle bracket extension  52  extending away from the frame coupling  50 . The extension  52  extends downwardly and rearwardly, as shown in FIG. 2, but other orientations are possible. The axle orifice  48  for mounting the wheelchair axle  54  is positioned in the axle extension  52 , and therefore the extension enables the axle to be vertically spaced apart from the elongated frame member  40 . 
     The elongated frame member  40  has built into its top surface and bottom surface a series of grooves  56 , defined by lands  60 . These grooves  56  extend laterally across the top and bottom surface of the elongated frame member  40 . A bolt or pin  62  can be inserted through the frame coupling in a manner to laterally rest in one of the lateral grooves  56  and thereby lock the axle bracket  44  into a fixed position longitudinally with respect to the elongated frame member  40 , as shown in FIGS. 3 and 11. Therefore, the axle bracket  44 , which is otherwise free to slide forward and rearward, i.e., longitudinally with respect to the elongated frame member  40 , becomes fixed by the insertion of the pin  62 . It is to be understood that numerous other arrangements of indexing the bracket  44  can be employed. For example, a series of bores or holes could be positioned through the elongated frame member, and a pin could be inserted through a selected bore. 
     An approximate centerpoint  64  of the axle bracket  44  can be defined at the intersection of a horizontal line  66 , vertically centered at the midpoint of the elongated frame member  40 , and a vertical line  68  centered on the pin  62 . It can be seen that the angle at which the bracket extension  52  extends away from the frame coupling  50  positions the axle orifice  48  slightly rearward from the bracket coupling  50 . This rearward spacing of the center of the axle orifice  48  from the center point  64  can be viewed as a longitudinal offset or spacing distance d between the centerpoint  64  and the axle orifice  48 . Hence, it can be seen that the axle orifice  48  is spaced apart from the frame coupling  50  in a direction longitudinally along the wheelchair frame member  40 . This longitudinal offset distance d can be any amount, but is preferably within the range of from about 1 to about 10 cm, and most preferably about 2.5 cm. The longitudinal offset d is established because the axle bracket extension  52  extends away from the frame coupling  50  at an angle  70  defined by the vertical line  68  and a line  72  connecting the centerpoint of the axle orifice  48  and the bracket centerpoint  64 . The angle  70  is preferably within the range of from about 10 to about 60 degrees. The longitudinal offset distance d enables the axle  54  to be positioned very close to any frame member, such as vertical rear member  36 , that it may encounter. 
     To provide even closer positioning of the axle to the vertical rear member  36 , the rounded distal end  74  of the axle bracket extension  44  is provided with a flat edge  76  on the side oriented away from the coupling  50 , i.e., to the left as shown in FIG.  2 . Likewise, the frame coupling  50  is provided with a flat edge  78  to enable the bracket  44  to be positioned as close as possible to the rear vertical strut  30 . 
     As shown most clearly in FIG. 3, the frame coupling  50  is yoke-shaped, having two spaced apart ears  80  defining a saddle  82 . The ears and saddle are configured to fit around the elongated frame member  40  so that the axle bracket can be slid along the elongated frame member for adjustment of the position of the axle. The pin  62 , which acts as a connector, links the ears  80  to attach the frame coupling  50 , and hence the axle bracket  44 , to the elongated frame member  40 . The coupling ears  80  have generally flat inner surfaces  86  to generally correspond to the generally flat sides  88  of the elongated frame member  40 . The pin  62  can be inserted through yoke bores  90 , and can be provided with a pin head  92  and can be secured to the yoke ears by a nut  94 . Other means for attaching the pin to the yoke ears can be used. 
     The axle bracket extension  52  is positioned in a plane substantially midway between the coupling ears  80 . A threaded axle sleeve  98  is mounted in the axle orifice  48  in the axle extension  52  for receiving the axle  54 . The axle sleeve can be secured to the axle bracket extension  52  with a pair of nuts  100 , or by any other suitable means. It is to be understood that numerous other axle mounting arrangements, such as a camber tube, can be used with the invention. 
     One of the advantages of the axle bracket of the invention is that it can be slid or adjusted along the length of the elongated frame member  40 , and can also be reversed and/or inverted for greater flexibility of positioning, as will be explained below. As shown in FIG. 4, the axle bracket  44 , mounted in the orientation shown in FIGS. 1-3, can be slid or moved rearward along the elongated frame member so that the axle orifice is as close as possible to the vertical rear member  36 . As shown in FIGS. 1 and 2, the rear side frame assembly  20  and the front side frame assembly are connected together by tube connectors  102  that enable the rear side frame assembly  20  to be easily disconnected from the front side frame assembly  22  as needed. 
     One of the advantages of the invention is that the pin  62  can be removed from the bracket to allow the bracket to be removed from the elongated frame member and replaced in a reversed orientation and/or in an inverted orientation. As shown in FIG. 5, the axle bracket  44  is installed in an orientation with the axle orifice  48  spaced longitudinally forward from the frame coupling  50 . Therefore, the axle bracket is configured so that it can be attached to the elongated frame member  40  in either of two opposite longitudinal directions, thereby enabling the bracket to be mounted with the axle tube orifice positioned either spaced longitudinally in one direction or spaced longitudinally in an opposite direction with respect to the frame coupling  50 . 
     As can be seen from FIG. 3, the bracket yoke is designed and configured so that can be inverted in its position on the elongated frame member  40 . Therefore, an additional range of positions for the axle orifice above the elongated frame member can be used, as shown in FIGS. 6 and 7. In FIG. 6, the axle orifice  48  is spaced apart from the axle bracket frame coupling  50  in a direction longitudinally rearward with respect to the elongated frame member  40 . In FIG. 7, the axle orifice  48  is spaced apart from the axle bracket frame coupling  50  in a direction longitudinally forward with respect to the elongated frame member  40 . By comparing the configuration of FIGS. 6 and 7 with the configuration of FIGS. 4 and 5, it can be seen that the bracket  44  can be attached to the elongated frame member  40  in either of two opposite orientations, i.e., up or down with respect to the elongated frame member, thereby enabling the bracket to be mounted with the axle tube orifice positioned on either one side or the other of the elongated frame member. 
     As shown in FIG. 8, the axle bracket  44  of the invention can be mounted for vertical movement along a modified rear vertical strut  106 , similar in position and function to the rear vertical strut  30  illustrated in FIGS. 1-7, but being adapted or structured with grooves  108  and lands  110  similar to the grooves  56  and lands  60  illustrated in FIGS. 1-7. A horizontal frame member  112  connects the rear vertical strut  106  with the vertical rear member  36 . The bracket  44  can be removed from the rear vertical strut  106  and replaced in a reversed and/or inverted orientation or direction in a manner similar to that shown in FIGS. 4-7. Therefore, it can be seen from FIG. 8 that the orifice is spaced apart from the frame coupling in a direction longitudinally along the wheelchair frame member, when that frame member is a vertically oriented frame member  106 , as well as when that frame member is a horizontally oriented frame member  40  as illustrated in FIGS. 1-7. It should be understood that the bracket  44  can be attached to the elongated frame member  40  in either of two opposite orientations, i.e., either forward or reward with respect to the vertically oriented elongated frame member  106 , thereby enabling the bracket to be mounted with the axle tube orifice positioned on either one side or the other of the elongated frame member. 
     As shown in FIG. 9, in an alternate embodiment of the axle bracket  114 , the extension member  116  is offset laterally from the lateral centerline  118  between the coupling ears for increased flexibility. This feature enables the bracket  114  to be reversed so that the lateral positioning of the extension member  116 , and hence of the axle sleeve  98  and drive wheel  16 , can be moved laterally inwardly or outwardly, as indicated by directional arrow  120 . The extension  116  has an orifice  48  for receiving a wheelchair axle  54 , and the orifice is spaced apart from the frame coupling  50  in a direction longitudinally along the wheelchair frame member. 
     In the embodiment of the axle bracket  134  shown in FIG. 10, the frame coupling comprises a single flange  138  rather than the opposed yoke ears  80  illustrated in FIGS. 3 and 9. The flange  138  includes a bore  140  that can be used for bolting the bracket to the elongated frame member in a similar manner to that described above. The extension  142  has an orifice  48  for receiving a wheelchair axle  54 , and the orifice is spaced apart from the frame coupling  134  in a direction longitudinally along the wheelchair frame member. 
     As shown in FIG. 3, the coupling ears  80  of the frame coupling  50  have generally flat or planar inner surfaces  86  to generally correspond to the generally flat sides  88  of the elongated frame member  40 . In an alternate embodiment of the invention shown in FIG. 12 the coupling ears  180  of the frame coupling  150  have non-planar inner surfaces  186  which generally correspond to the non-planar sides  188  of the elongated frame member  190 . Therefore, it can be seen in its broadest aspect, the invention includes an elongated frame member having a frame contact surface that is aligned with a bracket contact surface to prevent rotation of the bracket with respect to the elongated frame member. The two contact surfaces are preferably generally planar, as shown by the contact surfaces  86  and  88  in FIG. 3, but can also be of any shape, such as the shape of non-planar surfaces  186  and  188  shown in FIG.  12 . 
     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.