Abstract:
An adjustable backrest support provides a seat back angle adjustment that eases the task of adjusting the position of a wheelchair backrest while keeping the user seated in their wheelchair. In one embodiment, the adjustable backrest support includes a strut, an adjuster ring, an adjusting barrel nut, an angle adjuster, and a clamping system including a clamp. The clamp may include clamping screws that permit adjustment of the seat back reclining angle the angle or the seat back lateral position when loosened.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Application No. 61/946,737, filed Mar. 1, 2014, the disclosure of which is incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    This invention relates in general to wheelchairs. In particular, this invention relates to an angle adjustable backrest support for a wheelchair. This invention further relates to an angle adjustable backrest support for a wheelchair that also provides lateral positioning of the seat back relative to the seat base. 
         [0003]    Wheelchairs are typically intended to be used by persons having different size, physical constitutions, and impairments. These conditions are accommodated, in one respect, by providing adjustable seating systems that permit the seat and/or seat back to be positioned to the user&#39;s seated body contours. Many known seating systems provide a variety of adjustments but often require the user to be moved away from the seat portion to be adjusted. Thus, it would be desirable to provide a seat backrest adjustment mechanism that is easily adjustable, even when the user is seated. 
       SUMMARY OF THE INVENTION 
       [0004]    This invention relates to wheelchairs and, in particular, to adjustable backrests for wheelchairs. In one aspect of the invention, there is disclosed a wheelchair having a frame. In certain embodiments, the frame may include spaced apart side frame tubes. A strut is connected to the frame. An adjustable backrest support engages the strut such that the adjustable backrest support pivots angularly about the strut. The adjustable backrest support may be fixed in one of a plurality of angled positions. The adjustable backrest support may further be moveable along the strut and fixed in one of a plurality of lateral positions between the side frame tubes. 
         [0000]    In certain embodiments, a backrest is mounted for selective angular movement relative to the adjustable backrest support. The backrest is also mounted for selective axial movement relative to the adjustable backrest support and may be fixed in one of a plurality of height positions relative to the frame. In one embodiment, the selective angular movement may be an inclination angular movement relative to a side view of the frame. In other embodiments, selective angular movement may be a rotational angular movement substantially within a plane generally parallel to the adjustable backrest support. 
         [0005]    The adjustable backrest support includes a backrest riser that supports a seat back mount for selective axial movement to the plurality of height positions. The seat back mount has a hinge and an adjuster connection to selectively provide inclination angular movement. The adjustable backrest support includes a backrest reclining mount having an aperture that engages the strut and permits the angular pivoting movement about the strut and lateral movement along the strut of the support and backrest. An adjuster ring is disposed between the strut and the backrest reclining mount. The adjuster ring is rotationally fixed relative to the strut and moveable along the strut. The strut has a torque transmitting profile and the adjuster ring includes an aperture having a complementary profile that engages the strut. In certain embodiments, the strut is attached to opposing backrest mounting brackets that are selective attachable to the frame in one of a plurality of longitudinal mounting positions that define a seat depth. In other embodiments, the strut may be directly mounted to the frame. 
         [0006]    In certain embodiments, the backrest reclining mount includes a strut clamp positioned proximate to the aperture. The strut clamp including a pinch bolt and a deflection slot that cooperate to selectively fix the position of the backrest reclining mount relative to the strut. In certain other embodiments, the strut clamp may be two spaced apart strut clamps on opposite sides of a ring slot in the backrest reclining mount. The ring slot is shaped to accept the adjuster ring. The adjuster ring engages an angle adjuster that defines an adjustable support to maintain a previously set adjustment when the pinch bolt is loosened. The adjuster ring is positioned within the ring slot such that the adjuster ring aperture is coaxially aligned with the backrest reclining mount aperture, the adjuster ring engaging the angle adjuster such that movement of the angle adjuster causes the adjustable backrest support to rotate about the strut. In certain embodiments, the backrest reclining mount aperture further includes a limiter slot that limits a range of motion of the adjustable backrest support relative to the strut. 
         [0007]    In certain embodiments, the adjuster ring includes an adjuster slot that supports a barrel nut for relative rotational movement and constrained axial movement within the adjuster slot. The angle adjuster has a threaded portion that engages the barrel nut such that rotation of the angle adjuster rotates the adjustable backrest support relative to the strut. 
         [0008]    In another aspect of the invention, an adjustable wheelchair backrest assembly includes a backrest configured to support a user. The adjustable wheelchair backrest assembly further includes an adjustable backrest support having a backrest reclining mount and a backrest riser. The backrest reclining mount has an aperture and a strut clamp. A strut extends through the backrest reclining mount aperture in selective engagement with the strut clamp. The strut supports the adjustable backrest support for selective angular pivotal movement. The strut also supports the adjustable backrest support for axial movement along the strut to a plurality of lateral positions. A seat back mount is connected to the backrest. The seat back mount has a hinge pivotally connected to a slide block and a locking arm adjustably connected to the slide block to position the backrest in one of a plurality of inclination angle positions. The slide block engages the backrest riser for selective movement along the backrest riser to position the backrest in one of a plurality of height positions. In certain embodiments, the seat back mount is a compound angle seat back mount that permits the backrest to be rotated to a desired angle substantially within a plane generally parallel to the backrest riser. 
         [0009]    The strut includes a torque transmitting profile. The backrest reclining mount has a slot intersecting the backrest reclining mount aperture. The slot cooperates with the strut clamp to selectively fix the axial position of the adjustable backrest support relative to the strut. An adjuster ring is connected to the backrest reclining mount and engages the strut for selective angular reclining movement of the backrest. 
         [0010]    In yet another aspect of the invention, an adjustable backrest support for a wheelchair includes a strut, a clamp, an adjuster ring, and an angle adjuster. The strut has a torque resistive shape and spaced apart frame attachment ends. The clamp has an aperture configured to mate with the strut and at least one pinch bolt to selectively fix the clamp to the strut. The adjuster ring mates with the strut such that the adjuster ring can be moved laterally across the strut and is rotationally fixed relative to the strut. The angle adjuster cooperates with the adjuster ring and the clamp such that movement of the angle adjuster positions the clamp in an angular position relative to a wheelchair frame. 
         [0011]    In certain embodiments, the adjuster ring and angle adjuster cooperate to move a backrest reclining mount to one of a plurality of angular positions relative to the wheelchair frame and maintain the angular position when the clamp is moved to a released position. The clamp released position permits the backrest reclining mount to be axially moved along the strut to one of a plurality of lateral positions relative to the wheelchair frame. 
         [0012]    Various aspects 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 
         [0013]      FIG. 1  is a side view of an embodiment of an adjustable backrest support for a wheelchair in accordance with the invention. 
           [0014]      FIG. 2  is an exploded, perspective view of an embodiment of a backrest adjustment mount. 
           [0015]      FIG. 3  is a side view, in partial cross section, of the backrest adjustment mount of  FIG. 2  in a first position. 
           [0016]      FIG. 4  is a side view, in partial cross section, of the backrest adjustment mount of  FIG. 3  in a forward angle-adjusted position. 
           [0017]      FIG. 5  is a side view, in partial cross section, of the backrest adjustment mount of  FIG. 3  in a rearward angle-adjusted reclining position. 
           [0018]      FIG. 6  is an exploded, side view of a portion of an embodiment of the backrest adjustment mount of  FIG. 3 . 
           [0019]      FIG. 7  is an exploded, side view of a portion of another embodiment of the backrest adjustment mount of  FIG. 3 . 
           [0020]      FIG. 8  is an exploded, side view of a portion of yet another embodiment of the backrest adjustment mount of  FIG. 3 . 
           [0021]      FIG. 9  is an exploded, side view of a portion of yet another embodiment of the backrest adjustment mount of  FIG. 3 . 
           [0022]      FIG. 10  is a rear facing, elevational view of another embodiment of an adjustable backrest support for a wheelchair having a lateral adjustability. 
           [0023]      FIG. 11  is a side view of a portion of an embodiment of an adjustable backrest support for a wheelchair having a backrest 
           [0024]      FIG. 12A  is a rear facing, elevational view of another embodiment of an adjustable backrest support for a wheelchair having a second angle adjustment bracket assembly. 
           [0025]      FIG. 12B  is an exploded, side view of an embodiment of the second angle adjustment bracket assembly of  FIG. 12A . 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0026]    Referring now to the drawings, there is illustrated in  FIG. 1  an adjustable backrest support for a wheelchair, shown generally at  10 . The adjustable backrest support includes a backrest or seat back  12  connected to a seat back mount  14 . The seat back mount  14  is connected to a backrest riser  16  such that the backrest  12  is adjustable in a number of different height positions. The backrest riser  16  is connected to a backrest reclining mount, shown generally at  18 , that is supported on a wheelchair frame  20  by a backrest mounting bracket  19 . In one embodiment, the wheelchair frame  20  includes spaced apart side frame tubes. The backrest reclining mount  18  permits the recline angle of the backrest  12  to be adjusted relative to the wheelchair frame  20 . As shown in  FIG. 1 , the backrest reclining mount  18  permits movement of the backrest support  10  from an upright position (shown in solid lines) to a reclined position of the backrest support  10 ′ (shown in dashed lines). 
         [0027]    Referring now to  FIG. 2 , the backrest reclining mount  18  includes a clamp  22  having a riser mount  24  and a strut clamp  26 . The riser mount  24  is configured to retain the backrest riser  16  and support user applied loads from the backrest  12 . The strut clamp  26  includes an aperture  28  having a circumferential profile  28   a  that is configured to mate with a strut  30  having a torque transmitting or torque resistive profile  32 . In one embodiment, the strut  30  further includes attachment ends  30   a  and  30   b  that attach to the backrest mounting bracket  19 . The backrest mounting bracket  19  may connect to the wheelchair frame  20  in a number of lengthwise or longitudinal mounting positions that vary the depth of seating. In one embodiment, the strut  30  and mounting bracket  19  may be configured as a cross member that connects two sides, such as left and right sides of frame  20  together. In this way, mounting and reclining movement of the backrest assembly  10  is independent of any back cane structures (not shown). Though shown as a radially extending key, the torque transmitting profile  32  may be any suitable shape that is capable of transmitting a torque load applied thereto. In the illustrated embodiment, the circumferential profile  28   a  of the aperture  28  further includes a limiter slot  28   b  that cooperates with the strut  30  to permit assembly of the strut  30  through the aperture  28 . The limiter slot  28   b  is sized to permit the torque transmitting profile  32  of the strut  30  to be rotated through a range of motion relative to the aperture  28 . In certain embodiments, the limiter slot  28   b  may also act to limit the overall range of reclining motion of the backrest assembly  10 . 
         [0028]    The clamp  22  includes a deflection slot  34  or “saw slot” that permits the circumference of the aperture  28  to close around and firmly grip the mating surface of the strut  30 . The aperture  28  may be positioned, as shown, on both sides of the clamp  22  or may be a single aperture, either on one side or centrally located in the strut clamp  26 . Associated with the aperture  28  is a pinch bolt hole  36 . The pinch bolt hole  36  intersects the deflection slot  34  such that a pinch bolt  38  can draw the aperture  28  around the strut  30 . In the illustrated embodiment, a clamping barrel nut  40  is disposed in a hole  42 , that also intersects the pinch bolt hole  36  and is configured to engage the pinch bolt  38  to permit clamping of the clamp  22  to the strut  30 . Alternatively, a threaded end of the pinch bolt hole  36  or a conventional nut (not shown) may be substituted for the clamping barrel nut  40 . 
         [0029]    An adjuster ring, shown generally at  44 , includes a strut aperture  46  and an adjuster slot  48 . The adjuster ring  44  is configured to be inserted into a ring slot  50  , formed in the clamp  22  between the apertures  28 , as shown in  FIGS. 3-5 . Alternatively, if the aperture  28  is centrally located on the strut clamp  26 , the ring slot  50  may be one or two ring slots positioned where the apertures  28  are illustrated in  FIG. 2 . The adjuster ring  44  is inserted into the ring slot  50  such that the strut aperture  46  is generally in coaxial alignment with the apertures  28 . The strut aperture  46  is shaped so as to permit the strut  30  to extend therethrough and generally conform to the outer shape of the strut  30  and the torque transmitting profile  32 , as shown in the enlarged view of  FIG. 6 . The adjuster slot  48  is illustrated as a pair of spaced-apart oblong holes  48   a  and  48   b,  as shown in  FIGS. 3-5 , that accept an angle adjuster  52 . Alternatively, the adjuster slot  48  may be opened at the bottom, if desired. In the illustrated embodiment, the angle adjuster  52  is a shown as a threaded bolt though other structures may be used, if so desired. The angle adjuster  52  passes through an adjustment aperture  54  in the strut clamp  26 . The adjuster slot  48  includes an oblong nut aperture  56  that accepts an adjusting barrel nut  58  that threads onto the angle adjuster  52 . As shown in  FIGS. 3-5 , the nut aperture  56  permits the adjusting barrel nut  58  to move toward or away (illustrated as clockwise or counterclockwise rotation) from the strut  30  as the angle adjuster  52  is rotated. The end of the angle adjuster  52  may be supported, relative to the clamp  22 , by a cap  60  that may act as a bushing to locate the angle adjuster within the strut clamp  26  and also permit rotation of the angle adjuster  52 . 
         [0030]    As shown in  FIGS. 3-5 , rotation of the angle adjuster  52  relative to the adjusting barrel nut  58  rotates the clamp  22  about the strut  30 . Prior to adjustment, the pinch bolts  38  are moved to release the apertures  28  from the clamped position around the strut  30 . As shown in  FIG. 3 , the angle adjuster  52  is threaded into the adjusting barrel nut  58 , which is located within the adjuster slot  48 . When the angle adjuster  52  is rotated in one direction, the adjusting barrel nut  58  moves along the angle adjuster  52  and against the sides of the nut aperture  56 . This movement is enabled by the strut  30  being fixed to the wheelchair frame  20  and the strut aperture  46  of the adjusting ring  44  having a complementary profile to that of the torque transmitting profile  32  of the strut  30 . Additionally, the angle adjuster  52  may push against the strut clamp surface  26  in one direction and the cap  60  pushing during rotation in the opposite direction. As shown in  FIG. 4 , rotation of the angle adjuster  52  (counterclockwise for a right-hand threaded angle adjuster  52 ) rotates the clamp  22 , and thus the backrest  12  to a forward tilted position. Rotating the angle adjuster  52  in the opposite direction moves the clamp  22  to the reclined position shown in  FIG. 5 . The clamp  22  may adjusted to any intermediate angular position and fixed relative to the strut  30  by way of the pinch bolts  38 . 
         [0031]    Referring to  FIGS. 7-9 , there are illustrated different examples of various embodiments of torque transmitting profiles and corresponding strut apertures. It should be understood that these examples are not exhaustive of the shapes that may be used in accordance with various embodiments of the invention. It should be further understood that a corresponding adjuster ring (not shown) will have a strut aperture having a mating profile with the torque transmitting profile of the strut, as described above in the previous embodiment.  FIG. 7  illustrates a strut  130  having a keyway  132 . A clamp  122  having a round aperture  128 . may be provided without a limiter slot. Movement of the clamp  122  may be limited at either extremes of travel by the adjuster ring (not shown) locating against the ring slot (not shown) as illustrated in  FIGS. 3-5 .  FIG. 8  illustrates a strut  230  having a cam profile  232  and a clamp  222  having an aperture  228  and a limiter slot  228   b.    FIG. 9  illustrates a strut  330  having a portion of a hexagonal profile  332  and a clamp  322  having an aperture  328  and a limiter slot  328   b.    
         [0032]    Referring now to  FIG. 10 , the strut  30  is sufficiently long to provide a lateral adjustment of the backrest  12  relative to the wheelchair frame  20 . When the backrest reclining mount  18  is loosened (by way of the pinch bolts), the adjustable backrest support  10  may be moved to a second lateral position  10 ″. This adjustment permits compensation for users having spine curvature issues or an inability to sit upright in the chair. As shown in  FIG. 11 , the backrest  12  may be mounted to the seatback mount  14 , where the seatback mount  14  includes a hinge connection  14   a  and an adjuster connection  14   b  to provide an angular adjustment of the backrest  12  relative to the backrest riser  16 , for added comfort. The adjuster connection  14   b  is configured as a slotted locking arm extending from the backrest  12  that can be fixed in a plurality of inclination angles relative to a slide block  14   c  by way of a fastener, such as a bolt and nut, over-center clamp, or other locking arrangement. Alternatively, the slot may be formed in the slide block  14   c,  if so desired. The slide block  14   c  is configured to axially move along the backrest riser  16  to vary the height position of the backrest  12  relative to the frame  20 . The inclination angle of the backrest  12  may be moved to a second position  12 ′. Referring to  FIGS. 12A and 12B , another embodiment of an adjustable backrest support  400  may include a backrest  412  attached to a compound angle seatback mount  414 . The compound angle seatback mount  414  includes a pivot mounting plate  416  that attaches to the backrest  412 . The pivot mounting plate  416  includes a pivot stem  418  that attaches to a seatback angle adjusting bracket  420 , similar to the seatback mount  14 . An adjusting lever  422  permits the backrest  412  to be rotated to a desired angle substantially within a plane generally parallel to the backrest riser  16 , to a position such as backrest position  412 ″. 
         [0033]    The principle and mode of operation of this invention have been explained and illustrated in its preferred embodiment. However, it must be understood that this invention may be practiced otherwise than as specifically explained and illustrated without departing from its spirit or scope.