Abstract:
A center-of-gravity tilt-in-space wheelchair includes footrests extended to armrest height making the footrests part of the folding base of the wheelchair. This is accomplished by extended members which connect the seat and back to the footrests. The extended members thus rotate about the approximate center of gravity of the wheelchair occupant seated in the wheelchair making tilting and folding of the wheelchair lighter and easier. The upper portion of the wheelchair, which includes the seat and back, can be quickly and easily separated from the lower base which includes the footrests as an integral part.

Description:
RELATED APPLICATION  
       [0001]     This application claims the benefit of and priority to U.S. Provisional Application Ser. No. 60/728,134, filed Oct. 18, 2005, the contents of which are incorporated by reference herein in its entirety. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The invention relates to wheelchairs; and, more particularly, to a center-of-gravity tilt-in-space wheelchair that easily and quickly collapses into a folded position.  
         [0004]     2. Related Art  
         [0005]     Tilting wheelchairs are well known. Such wheelchairs are typically used in highly dependent or geriatric care, wherein the ability to reposition a wheelchair occupant in various angular positions is beneficial to the occupant&#39;s health and daily routine. Tilting a wheelchair occupant relieves pressure to the wheelchair occupant&#39;s ischial tuberosities (i.e., the bony prominence of the buttocks). Continuous pressure to the wheelchair occupant&#39;s ischial tuberosities, which is applied when the wheelchair occupant remains in a single seated position, can cause the development of decubitus ulcers (i.e., pressure sores). For wheelchair occupants with severe kyphosis (i.e., curvature of the spine), seated tilting may allow the occupant to look forward and interact with their surroundings. Tilting may also be beneficial to assist with proper respiration and digestion.  
         [0006]     Some wheelchair occupants require attendant care, wherein an attendant is responsible for positioning the wheelchair seat angle, often changing the angle on a prescribed schedule. The ability to tilt the wheelchair occupant offers the occupant a variety of positions that accommodate their daily schedule, including, for example, an anterior tilt for eating at a table and posterior tilt for resting.  
         [0007]     Conventional tilting wheelchairs consist of a seat frame that is pivotally mounted to a base frame so that the seat frame tilts to reposition the wheelchair occupant. The pivot axis is typically mounted between the base frame and seat frame, towards the rear of the seat and away from the occupant&#39;s center of gravity. Tilting the occupant involves lifting or lowering his or her center of gravity and therefore requires effort on the part of the attendant. Mechanisms, such as springs or gas cylinders, are often employed to assist in tilting the occupant. Typically, levers are attached to handles on a tilting wheelchair. The levers allow an attendant to release a locking mechanism, change the tilt angle by pushing or pulling on the handles, and engage the locking mechanism, which fixes the tilt angle.  
         [0008]     Tilting in conventional tilt wheelchairs may invoke a reaction on the part of the occupant who experiences the sensation of being tipped over. The occupant experiences a sensation of being pitched off balance during tilting. Conventional tilt wheelchair designs involve translation of the wheelchair occupant&#39;s center of gravity during tilting. Significant effort on the part of the attendant may be required to tilt the wheelchair occupant when the occupant&#39;s mass translates during tilting. Moreover, conventional tilt wheelchairs require large base frames and anti-tip devices because tilting the chair displaces the occupant&#39;s center of gravity fore and aft over the wheelbase, potentially placing the wheelchair off balance.  
         [0009]     Certain prior art wheelchairs of the tilt-in-space type are known that are vertically collapsible from an upright position that allows the seat and back to tilt as a unitary structure. This is to provide for storage and transportation of the wheelchair while providing a comfortable seating for the user.  
         [0010]     Known tilt-in-space wheelchairs have the legs or footrests attached directly to the seat. This keeps the relative position of the footrests to the seat constant. Since the legs or footrests are an extension of the seat structure, it is consequently difficult to stabilize. This also makes it difficult and awkward to fold the wheelchair for storage and transportation.  
       SUMMARY  
       [0011]     There is a need for a tilt-in-space wheelchair where the seat and back assembly is not integral with the footrests so that the upper set and back assembly can be quickly and easily removed from the lower base assembly while retaining the advantages of a tilt-in-space wheelchair.  
         [0012]     It is an object of this invention to provide a tilt-in-space wheelchair which maintains the relative position of the footrests to the wheelchair seat during tilting of the wheelchair.  
         [0013]     It is another object of this invention to provide a tilt-in-space wheelchair where the seat and back assembly is not integrated with the footrests making removal of the same lighter and easier.  
         [0014]     It is still another object of this invention to provide a tilt-in-space wheelchair which is easier to fold.  
         [0015]     These and other objects are carried out by providing a tilt-in-space wheelchair where the footrests are extended to armrest height making the footrests part of the folding base of the wheelchair. This is accomplished by extended members which connect the seat and back to the footrests. The extended members thus rotate about the approximate center of gravity of the wheelchair occupant seated in the wheelchair making tilting and folding of the wheelchair lighter and easier. 
     
    
     BRIEF DESCRIPTION OF THE DRAWING  
       [0016]     The above-mentioned features and objects of the present disclosure will become more apparent with reference to the following description taken in conjunction with the accompanying drawings wherein like reference numerals denote like elements and in which:  
         [0017]      FIG. 1  is a front perspective view of the center-of-gravity tilt-in-space wheelchair according to the teachings of the invention, parts thereof being omitted for convenience of illustration;  
         [0018]      FIG. 2  is a side perspective view of the wheelchair of  FIG. 1 ;  
         [0019]      FIG. 3  is a view similar to  FIG. 1  illustrating a tilted position of the wheelchair thereof;  
         [0020]      FIG. 4  is a side view of the wheelchair of FIGS.  1  to  3  in a fully reclined position;  
         [0021]      FIG. 5  is a side view of the wheelchair of  FIG. 4  in a subsequent tilted position;  
         [0022]      FIG. 6  is a front perspective view of the wheelchair of FIGS.  1  to  5  illustrating removal of the seat and back assembly from the bottom base assembly;  
         [0023]      FIG. 7  is a schematic illustration of the latching and pivoting means of the wheelchair of FIGS.  1  to  6 ;  
         [0024]      FIG. 8  is a schematic illustration of the tilting of the wheelchair of FIGS.  1  to  7  up to 60°;  
         [0025]      FIG. 9  is a view similar to  FIG. 8  illustrating reclining of the back of the wheelchair of FIGS.  1  to  8 ;  
         [0026]      FIG. 10  is a schematic view illustrating the separation of the seat and back unit from the base unit of the wheelchair of FIGS.  1  to  9 ;  
         [0027]      FIG. 11  is a schematic view of the base unit alone of the wheelchair of FIGS.  1  to  10  after separation of the seat and back unit;  
         [0028]      FIGS. 12 and 13  are schematic views of the folded seat and back assembly and folded base assembly alone,  FIG. 13  showing the base assembly in an upright vertical position;  
         [0029]      FIG. 14  is a schematic view of the folded sections of  FIGS. 12 and 13  stored as a unit;  
         [0030]      FIG. 15  is a detailed view of a portion of the wheelchair of  FIG. 1  illustrating portions of the operating mechanism thereof;  
         [0031]      FIG. 16  is a perspective view of a portion of the apparatus of  FIG. 15  removed from the sleeve housing;  
         [0032]      FIG. 17  is a detailed view of a portion of the wheelchair of  FIG. 1  illustrating the foot operating mechanism thereof;  
         [0033]      FIG. 18  is a detailed view of the operating mechanism of  FIG. 15  showing another orientation thereof and actuation of the unlocking lever;  
         [0034]      FIG. 19  is a detailed view of a portion of the wheelchair of  FIG. 1  illustrating the quick release mechanism;  
         [0035]      FIG. 20  is a view similar to  FIG. 13  showing the base assembly in a folded horizontal position;  
         [0036]      FIG. 21  is a detailed view of a portion of the operating mechanism of  FIG. 15 ;  
         [0037]      FIG. 22  is a view taken along lines  22 - 22  of  FIG. 21 ;  
         [0038]      FIG. 23  is a detailed view of a portion of the operating mechanism of FIGS.  17  to  19 ; and  
         [0039]      FIG. 24  is a detailed view of a portion of the view in  FIG. 23 . 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0040]     Referring now to  FIG. 1  of the drawing, a tilt-in-space center-of-gravity wheelchair  10  in accordance with the teachings of the invention is shown. The wheelchair  10  has a base frame  12  and a seat assembly  14  supported by base frame  12 . Base frame  12  is supported on a supporting surface by wheels, such as a pair of spaced front casters  15 ,  16 , and spaced rear wheels  18 ,  19 .  
         [0041]     The seat assembly  14  has a seat frame in the form of spaced longitudinally extending tubes  20 ,  21  (see also  FIG. 6 ) for supporting a seat  22 . Any suitable seat may be provided, such as the planar seat shown in  FIG. 1 . Such seat may be semi-rigid or rigid, padded, contoured, foldable, a contoured profile seat, or a lightweight sling seat as is well known in the wheelchair art. The seat frame also includes a seat back  24  comprises of a pair of spaced rods  25 ,  25 ′ supporting therebetween a back support  26  (see also  FIG. 2 ). A U-shaped rod  100  may interconnect rods  25 ,  25 ′. Back support  26  may be padded or of stretched canvas and adjusts to the back of the occupant.  
         [0042]     Rods  25 ,  25 ′ may be telescopingly adjustable as is well known in the wheelchair art, and terminate at top in a generally U-shaped handle  28 . Handle  28  is secured to contoured couplings  60 ,  61  ( FIG. 1 ) pivotally connected via pivot pins  62  (only one visible in  FIG. 1 ) to couplings  30 ,  30 ′ that are adapted to releasably hold handle  28  in fixed relation to rods  25 ,  25 ′ in a variety of positions as is well known in the art.  
         [0043]     A pair of spaced armrests  31 ,  32  ( FIG. 1 ) are provided mounted to rods  63 ,  64  extending to brackets  67 ,  68  (see particularly  FIG. 6 ) which, as will be discussed further, are releasably attached to release latches  65 ,  66  ( FIG. 1 ) fixed to back support  26 , having extending knob elements  93 ′ ( FIG. 6 ) releasably mounted in U-shaped slots  92 ′ in latches  65 ,  66  in a quick release manner as is well known in the wheelchair art. These knob elements  93 ′, slots  92 ′ and latches  65  to  68  form cylindrical mechanical locks as will be discussed.  
         [0044]     A pair of spaced footrests  35 ,  36  ( FIG. 1 ) are provided. The underside of each footrest (see  FIG. 3 ) is secured to a sleeve  69  through which rod  70  extends. Rod  70  has caps  71  at each end. As particularly contemplated in the present invention, each footrest is connected to its respective armrest (thus, footrest  36  is connected to rod  37  which is telescopingly mounted in rod  38  and adjustable therein as indicated by holes  72  (in rod  38 ) and spring biased elements  73  (in rod  37 ) again as is well known in the art. Rod  38  is in turn connected to approximately the middle bottom of armrest  32 . Rods  38  extend through spaced mounting sleeves  39  below armrest  32  as will be discussed. Footrest  35  is connected to armrest  33  in like manner.  
         [0045]     Base frame  12  ( FIG. 1 ) includes spaced opposing side tubes  40 ,  41  extending at one end to sleeves  39  and at the other end to caster housings  42 ,  43  which support caster yokes  44 ,  45  on which casters  15 ,  16  are rotationally mounted, as is well know in the art. Rear wheels  18 ,  19  can also be mounted in any suitable manner, as by being rotatably mounted to the lower end of spaced tubings  74 . A conventional quick release brake lever assembly  75  is also mounted to tubing  74  adapted to engage wheel  19 .  
         [0046]     A front rod  47  connects tubes  40 ,  41 . The frame of the wheelchair  10  also includes rod  74  connected at top to sleeves  39 . Rods  74  are connected via brackets  50 , to sleeve  39 .  
         [0047]     Side tubes  40 ,  41  are pivotally connected to brackets  80  which are in turn pivotally connected to brackets  81 . Brackets  81  are pivotally connected to tubings  74 . Tabs  82  (see also  FIG. 6 ) are welded to tubings  74  ( FIG. 15 ) and to the lower end of a conventional mechanical lock  104  (see also  FIG. 16 ) mounted in sleeve  85  as will be discussed. Rod  86  extends through mechanical lock spring  105  in sleeve  85  and a stop  87  ( FIG. 2 ) is provided at the bottom of rod  86 .  
         [0048]     Rods  38  extend through quick release latches  88  also coupled to tubes  21  and to seat  22 . As will be discussed, each latch  88  ( FIG. 6 ) has a U-shaped slot  92  receiving a knob element  93  therein extending from tubes  20 ,  21  in quick release engagement as is well known in the wheelchair art.  
         [0049]     Back support  26  is pivotally connected via spaced brackets  89 , to brackets  90  fixedly secured to seat  22 . Also, as seen in  FIG. 3 , tubes  20 ,  21  are wrapped with the material comprising seat  22  to secure the same thereto. A U-shaped bracket  91  ( FIG. 3 ) is coupled to tubes  20 ,  21  at the bottom for added support. A like bracket  103  ( FIG. 6 ) is coupled to rods  63 ,  64  at the point of connection of brackets  67 , 68 .  
         [0050]     Each release latch  65 ,  66 ,  88 , such as latch  88  in  FIG. 19 , is actuated by a lock release lever  116  pivotally mounted on flange  117  of latch  88 . When the pins are mounted in their respective slots, such as slot  92  in  FIG. 19 , spring based locking pin  118  enters hole  119  in slot  92  (see  FIG. 6 ) and is locked therein until lock release lever  116  is pulled to push pin  118  out of hole  119  to thereby disengage roller  93 .  
         [0051]     The operation of the wheelchair  10  of the invention is shown schematically in  FIG. 7 . The docking latches and pivot points are at points X and Y. Latches  88 , slots  92  and knob elements  93  are at point X, and latches  65  to  68 , slots  92 ′ and knob elements  93 ′ are at point Y. This allows disconnect of the back latch and swinging down of the seat assembly  14  (seat assembly  14  and back  24  shown in dotted lines) for easy folding. As seen, the tilting footrest/armrest member is permanently attached to the base frame  12 .  
         [0052]      FIG. 8  illustrates the upper or top wheelchair unit of wheelchair  10  tilting from a 90° upright position up to 60° therefrom when the foot operated mechanical lock is engaged.  
         [0053]      FIG. 9  illustrates how the armrests  31 ,  32  can be extended by the rods  86  to move the seat back  26  to the reclined position shown in dotted lines.  
         [0054]     Although various systems are known for operating the mechanisms of wheelchair  10 , as seen in  FIG. 1 , a side lock mechanism  106  is mounted to bracket  81  (see also  FIG. 15 ) having a cable  107  extending through a sleeve  108  down through tubing  109 .  
         [0055]     Although any suitable release mechanism may be used, I contemplate a locking cable  110  coupled to a mechanical locking device of the type manufactured and sold by P. L. Porter Controls, Inc. of Burbank, California under the name “Mechlok”, which is a registered trademark. A Mechlok is a mechanical, linear locking device that combines the rod, housing, bushings, locking springs, actuation lever, and attach ends into a fully integrated assembly. It consists primarily of a steel rod gripped by two locking springs that bear against specially configured holding bushings swaged into a surrounding tubular housing.  
         [0056]     These single mechanical locks have one maximum stroke setting that can lock at any position of the travel range and have positive locking capabilities in both directions. There are many sizes and strokes to suit all applications up to 2,000 lbs. [8,896 N] axis load.  
         [0057]     A compression spring also provides a variable return force to return the lock back to the fully extended position.  
         [0058]     Cable  110  is connected at bracket  112  ( FIG. 15 ) to sleeve  85  and extends into the interior thereof where it engages the extended mid-portion  111  ( FIG. 16 ) of spring  105  for actuating the same, by twisting to unlock spring  105  from engagement with shaft  86 , as is well known in the art.  
         [0059]     The cable release is foot operated. Thus, as seen in  FIG. 17 , a foot pedal disk  114  is provided actuated by foot operated lever  113 . As seen in  FIG. 15 , side lock mechanism  106  is in the form of a round plate and a pointed projection  121  on lever  115  sits in a matching notch  122  in plate  106 . By lifting lever  115  in a clockwise direction, projection  121  is lifted out of engagement with matching notch  122  ( FIG. 18 ) while simultaneously the cable  107  in tubing  109  is pulled which actuates the foot pedal disk  114 , as will be discussed.  
         [0060]     Since it is desired to have a single cable actuate both mechanical locks  104 , as seen in  FIGS. 23 , and  24 , cable  123 , which extends through tubing  110  from disk  114 , extends through an end cap  129  of tubing  124  to a cylindrical coupler  125  mounted in a curved area  126  of a cable spacer  127 . Spacer  127  has a first outer curved portion  128  through which a first cable  130 , secured to coupler  125 , extends. A second cable  131  extends from coupler  125  through a second outer curved portion  132  of spacer  127 . Cables  130 ,  131  extend to the center spring  111  of each mechanical lock  104  as seen in  FIG. 22  (only cable  130  shown in  FIG. 22 ).  
         [0061]     Cable  123  ( FIG. 23 ) extends through the area between curved portions  128 ,  132  of spacer  127  to a nut assembly  133 . Nut assembly  133  has a throughbore  134 , through which cable  123  extends, and is secured therein by threaded screws  135 ,  136 . Both cables  130 ,  131  extend through a second end cap  137  ( FIG. 23 ) and respective tubings  138 ,  139  to each respective mechanical lock as seen in  FIG. 22 . It is to be understood that the parts shown in  FIGS. 23 and 24  are assembled inside of tubing  124 , end caps  129 ,  137  closing off the open ends. When cable  123  is pulled, the left and right hand mechanical locks  104  are operated simultaneously.  
         [0062]     In operation, the wheelchair  10  is in the  FIG. 2  position. Footrests  35 ,  36  are pulled away from rods  40 ,  41  as seen in  FIG. 4 . Rods  37  telescope within rods  39  and the back  26  moves backwardly as the seat  22  moves upwardly (see  FIG. 3 ), then to the  FIG. 5  position.  
         [0063]     When it is desired to disassemble wheelchair  10 , as for storage and the like, as seen in  FIG. 6 , brackets  65 ,  66  and knob elements  93 ′ are released from brackets  67 ,  68  by release of knob elements  93 ′ from slots  92 . Similarly, knob elements  93  are removed from brackets  88  in like manner. The seat  22  and back  26  assembly shown at top in  FIG. 6  can be quickly and easily removed from the bottom assembly in the direction of the arrow  200  ass shown schematically in  FIG. 10 .  
         [0064]     The bottom assembly alone, after removal of the seat and back assembly, is shown in  FIG. 11 .  FIGS. 12 and 13  illustrate folding of each of the assemblies shown in  FIG. 11 . As seen in  FIG. 12 , the seat  22 , back  26  and handle  28 , are folded into one unit. As seen in  FIG. 13 , the armrests  31 ,  32  and the tubes and rods of base frame  12  are folded into one unit. See also  FIG. 20  wherein the folded base assembly is in a horizontal position. As seen in  FIG. 14 , the folded seat and back assembly can be stored within the folded bottom assembly, by engaging the knob elements  93  on the seat tubes  20 ,  21  within slots  92  of the latches  88  of the bottom assembly.  
         [0065]     It can be seen that there is disclosed a tilt-in-space wheelchair which consists of a sturdy member extending from the footplates to the armrests, and pivoting on the chair base close to the center of gravity of the seat and occupant. This member, which is an integral part of the base, supports the removable seat assembly so that the seat, footrests, and armrests tilt as a unit. The angle of the pivoting member is such that, as the occupant gets larger, the footrests adjust appropriately down and forward to match the seat depth forward extension and the occupant&#39;s longer leg length.  
         [0066]     This allows for a tilt-in-space feature, with firm leg/footrests, and maintains the relative position of the footrests to the seat during tilting. The legrests are no longer extensions of the seat, making removal of the seat/back from the base lighter and easier. The integration of the legrests with the base makes the chair much easier to fold.  
         [0067]     Different seating systems may be used. The wheelchair may be folded into a compact assembly with the seat attached. It tilts and reclines as desired, has an adjustable width, wheelbase and footrests. The footrests stay with the base frame and are non-elevating.  
         [0068]     Although a particular variation of the invention is disclosed, variations thereof may occur to an artisan and the scope of the invention should only be limited by the scope of the appended claims.