Abstract:
A disclosed walker is a three sided framework allowing quick connect/disconnect to the frame of a conventional standard wheelchair. The walker is formed with a front and two side assemblies pivotally linked to the front assembly. When the walker is not connected to a wheelchair, the side assemblies and front assemblies pivot and collapse into a “z” pattern forming a flat, compact package. For connection to a wheelchair, the sides assemblies unfold perpendicularly to the front assembly, and are locked into place by a horizontal crossbar. U-shaped securing clips located at the rear ends of the walker&#39;s side assemblies, drop over and straddle horizontal frame members of the wheelchair tightly grasping the wheelchair&#39;s frame members. The stability of the walker/wheelchair combination is enhanced by outward bends of the front vertical sections of the walker which terminate in swivel caster supports.

Description:
FIELD OF THE INVENTION 
     This invention relates to a walker, and in particular, to a walker for attachment to a conventional wheelchair. 
     BACKGROUND OF THE INVENTION 
     Walkers have long been known which provide a frame that can be grasped by a person with limited walking capability to allow the person to walk. The frame typically has legs that rest on the ground through wheels, non-rolling bases or some combination of both. 
     A device known by the trademark “Merry Walker,” provided by Diller Medical, Inc. is commonly utilized for the cognitively impaired yet ambulatory patient. These patients require support with ambulation and a sitting device when tired, these patients are unable to independently use a free standing assistive device for ambulation or to independently maneuver to a free standing chair to sit down when fatigued. this device is useful for the cognitively impaired patient to ambulate without supervision. However, several limitations exist, such as difficulty transferring patients into the “Merry Walker,” storage of multiple devices within the facility, costs, transferring patients within the facility and extended seating comfort. Because other devices use four caster wheels the patient has a tendency to turn the device sideways. 
     The mating of a walker to an associated wheelchair as an aid to a partially ambulatory patient has been addressed in a variety of patents in the prior art. U.S. Pat. No. 3,398,974, dated Aug. 27, 1968 discloses a walker rigidly mounted to wheelchair wherein the walker, when not in use, is stowed by removing its horizontal support crossbar and pivoting its side members alongside, and extending mostly behind the wheelchair proper; the walker side assemblies remaining attached to the wheelchair. Also disclosed is a spring loaded braking system that actuates when the patient applies downward pressure on the walker&#39;s handle grips. 
     U.S. Pat. No. 2,596,055 discloses a walker detachable from a wheelchair having mating attachment tubes that are permanently secured to the wheelchair. Use of this walker requires modification to the structure of the wheelchair, and the walker can only be used with a wheelchair that has been so modified. The detached walker remains an assembled, bulky unit, inconvenient for storage. 
     The present invention provides a walker usable with a conventional unmodified wheelchair, and that further addresses problems of stowage and stability in an effective and simplified manner. 
     SUMMARY OF THE INVENTION 
     The walker of the invention is a three sided framework providing a front and sides for a wheeled walker. The walker includes clips allowing quick connect/disconnect to the frame of a conventional standard wheelchair, so that the wheelchair provides a rear for the walker and a seat with the walker. The walker frame is formed with a front assembly and two side assemblies that are pivotally linked to the front assembly. When the walker is not in use, and is not connected to a wheelchair, the side assemblies pivot and fold such as in a “z” pattern, against the front assembly to form a collapsed, removable, compact package. When assembled for connection to a wheelchair, the sides assemblies unfold perpendicularly to the front assembly, and are locked into place by a horizontal crossbar, which also serves as an extra handgrip for the patient. The clips are located at the rear ends of the walker&#39;s side assemblies, and drop over and straddle horizontal frame members of the wheelchair. Tethered pins can then be pushed through the legs of the clips so that the clips tightly grasp the wheelchair&#39;s frame members. 
     The stability of the walker/wheelchair combination is enhanced by outward bends of the front vertical sections of the walker which increase the side to side width of the walker at a base of the walker but allow portions of the walker above the bands to be narrower to clear obstructions when moving. These section&#39;s ends terminate in swivel caster supports. The walker has two front caster wheels or other wheels mounted in the caster supports. The supports are preferably provided with side stops that limit the angles by which the casters may swivel away from the forward direction. It has been determined that an angular deflection of plus or minus 60° relative to the forward direction provides acceptable stability. The casters cannot rotate into the 90° positions which would allow the front of the walker to roll in the sideways direction. If the standing patient begins to fall to the side, or to fall backwards, the swivel wheels pivot into the angularly limited stopped positions, at which point they cannot rotate, but slidingly resist movement of the walker due to the frictional force between the caster&#39;s tires and the flooring. Thus, built-in protection against unwanted tipping and instability is provided. 
     OBJECTS OF THE INVENTION 
     Accordingly, a primary object of the present invention is to provide a walker which is attachable to a front end of a wheelchair to allow a person to use the walker in a standing position to move and keep a wheelchair with an associated seat nearby for resting purposes. 
     Another object of the present invention is to provide a walker attachable to a front end of a wheelchair which can be readily removed and collapsed for storage when not in use. 
     Another object of the present invention is to provide a walker attachment to a wheelchair which does not require modification of the wheelchair in any way. 
     Another object of the present invention is to provide a walker attachment to a wheelchair which is highly stable and resists tipping over, especially laterally. 
     Another object of the present invention is to provide a walker attachment for a wheelchair which includes a breaking mechanism which causes wheels of the walker to be automatically braked when the walker is moving laterally, such that unwanted lateral movement can be more easily resisted by the user. 
     Another object of the present invention is to provide a walker attachment for a front of a wheelchair which can be readily formed from commonly available materials. 
     Other further objects of the present invention will become apparent from a careful reading of the included drawing figures, the claims and detailed description of the invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of the walker of this invention attached to an associated wheelchair. 
     FIG. 2 is a perspective view of the walker of this invention alone, showing its assembled configuration. 
     FIG. 3 is a perspective view of the walker of this invention alone, showing its folded configuration. 
     FIG. 4 is a perspective exploded parts view of the clip of the walker of the invention for connecting the invention to a wheelchair. 
     FIG. 5 is a perspective view of a caster support and its associated caster with portions cut away to reveal interior details. 
     FIG. 6 is a bottom plan view of the caster and support of FIG. 5 illustrating the angular limits of swiveling of the caster. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to FIG. 1, a walker  10  connected to a wheelchair  12  is shown in use by a patient  14 , illustrative of a preferred embodiment of this invention. It will be noted that the walker  10  is preferably fastened to horizontal structural members  18  of the wheelchair  12  by means of two clips  16 . The clips  16  are secured to the rear vertical sections of the walker  10 , legs  86 ,  88  (FIG. 4) of the clips  16  straddle the structural members  18  of the wheelchair  12  to fasten the walker  10  to the wheelchair  12 . It will be noted than the wheelchair  12  requires no modification to accept the clips  16  of this preferred embodiment. 
     As seen in FIG. 2, the walker  10  of this invention  10  is a three sided framework having side assemblies  20 ,  22  and a front assembly  24 . The assemblies  20 ,  22 ,  24  are preferably fabricated from a tubular plastic, such as PVC, or light weight metal, such as aluminum. Side assembly  20  includes the upper horizontal section  28 , lower horizontal section  44 , front vertical section  32  and rear vertical section  48 . Sections  32 ,  28 ,  48  may be fabricated from a single piece formed in the shape of an inverted “U,” and horizontal section  44  is optionally rigidly connected to the vertical sections  32 ,  48  as a stiffening member. Side assembly  22  is similarly fabricated with vertical sections  34 ,  50 , top horizontal section  30  and optional rigidly connected stiffener  46 . 
     The upper horizontal sections  28 ,  30  of the sides  20 ,  22  are also available as hand-holds for the patient  14 . These sections  28 ,  30  can be provided with high friction surfaces such as grips to allow the sections  28 ,  30  to be more easily grasped. The lower ends of the vertical sections  32 ,  34  of the side assemblies  20 ,  22  have offset ends  36 ,  38  to increase the width and the stability of the walker  10 , and the offset ends  36 ,  38  terminate in casters  100 ,  102 . 
     An important feature of the invention is the interconnection of the side assemblies  20 ,  22  and the front assembly  24 . The front assembly  24  includes the horizontal sections  52 ,  54 . A horizontal pivotable crossbar  26  serves as a handgrip for the walking patient  14 , as well as providing structural rigidity to the walker  10 . Section  52  has pivots  58 ,  62  at its ends. Preferably, the pivots  58 ,  62  are in the form of cylindrical tubes sized slightly larger than the tubes forming the vertical sections  32 ,  34 . Pivot  58  attaches one end of section  52  to the vertical section  32 , and similarly, pivot  62  attaches the other end of section  52  to the vertical section  34 . 
     The attachments of the pivots  58 ,  62  are such that free rotational movement about the vertical sections  32 ,  34  is allowed, while the location of the pivots  58 ,  62  is fixed along the vertical sections  32 ,  34  so that displacement of the section  52  in the direction along the vertical section  32 ,  34  cannot occur. Similarly, pivots  56 ,  60  attach the ends of horizontal section  54  to vertical sections  32 ,  34  so that rotation relative to vertical sections  32 ,  34  is allowed for horizontal section  54 , while its displacement along the vertical sections  32 ,  32  is prohibited. 
     The crossbar  26  is also provided with a freely rotating pivot  64 , preferably in the form of a cylindrical sleeve which pivotally attaches one end of crossbar  26  to a fixed location of horizontal section  28 . The other end of crossbar  26  terminates in a cupped partially cylindrical surface  66  which fits over the horizontal section  30 . With the cupped surface  66  mating with the section  30 , a hole  68  in the cupped surface  66  aligns with a hole  70  in horizontal section  30 , and a removable pin  72  through the holes  68 ,  70  ties the crossbar  26  to the horizontal section  30 . The crossbar  26  thus rigidly ties the side assembly  20 , the side assembly  22  and front assembly  24  together, and provides the walker  10  with the structural stiffness requisite for use. 
     With the above description in mind, the convenient stowage of the walker  10 , when not attached to the wheelchair  12 , may be understood by referring to FIGS. 2 and 3. In stowing the unit, the pin  72  securing the crossbar  26  to the horizontal section  30  is first removed. This frees the cupped surface  66  end of the crossbar  26 , and the crossbar  26  is now lifted and rotated by 270° about the pivot  64  so that the crossbar  26 , while remaining attached to the horizontal section  28  by pivot  64 , lies alongside side assembly  20 . 
     The front assembly  24  may now be rotated about pivots  56 ,  58  so that the front assembly  24  is positioned parallel to, and up against, the side assembly  20 . Simultaneously, the side assembly  22  is rotated about the pivots  60 ,  62 , so that the side assembly  22  comes to rest alongside, and parallel to, the folded front assembly  24 , the folded walker assemblies assuming a collapsed “Z” shaped configuration when viewed from above. The entire walker  10  can then be easily stored as a compact, flat package, independent of the wheelchair  18 , as illustrated in FIG.  3 . 
     The clips  16 ,  17  which allow the walker  10  to attach to the wheelchair  12  are preferably removably attachable to the vertical sections  48 ,  50 . Preferably, this location where removable attachability of the clips  16 ,  17  is provided is above the jog in the vertical sections  48 ,  50 . When the clips  16 ,  17  and associated portions of the vertical sections  48 ,  50  are removed including the jog, the remaining portions of the vertical sections  48 ,  50  extend linearly. 
     Replacement legs of a linear nature can be provided which removably attach to the remaining portions of the vertical sections  48 ,  50  after the clips  16 ,  17  and associated jogged portions of vertical sections  48 ,  50  have been removed. These legs would be sufficiently long that they would extend down to the floor. Hence, the walker  10  would, when configured with these straight replacement legs, have a configuration similar to that of a standard walker. In this way, the walker  10  can attach to a wheelchair  12  in one mode, be used as a stand alone walker in a second mode with two non-wheeled legs resting on the floor and two wheeled legs resting on the floor, and in a third mode be folded up for storage with either the straight lower portions of the vertical sections  48 ,  50  or with the clips  16 ,  17  and included jogged portions of lower vertical sections  48 ,  50 . 
     Referring again to FIG. 1, the walker  10  is preferably attached to wheelchair  12  horizontal member  18  by two quick/connect clips  16 ,  17  affixed to the bottom ends of vertical sections  48 ,  50  (FIGS.  2  and  3 ). Just above the clips  16 ,  17  the vertical sections  48 ,  50  preferably jog in toward each other. In this way, they are positioned to match the width of the wheelchair  12  at the clips  16 ,  17  but be wide enough to orient the vertical sections  48 ,  50  on outboard sides of the wheelchair  12 . 
     Referring to FIG. 4 the detail of the clips  16 ,  17  assemblies shows one of the clips proper, e.g.  16  which is secured to the base of one of two end-caps  74 ,  76 , e.g.  74 , by means of hardware consisting of, e.g. washers  78 ,  80 , bolt  84  and nut  82 . The end of the vertical section, e.g.  48 ′ fits tightly into the end cap  74 , and may be further secured in place by means of an appropriate adhesive. (In the drawings, related elements are designated by the same reference number, albeit they are distinguished by primes.) The clip  16  has two legs  86 ,  88  which lead to a slot  90  through the body of the clip  16 . 
     In attachment of the walker  10  to a wheelchair  12 , the clips  16 ,  17  slip over the horizontal members  18  of the wheelchair  12 , and the slot  90  captures the horizontal member  18 . A hole  92  extends through the legs  86 ,  88  and a pin  94  having a spring loaded ball  98  holds the clip  16  in place. The pin  94  is provided with a ring  96  for convenience in removal of the pin  94  from the clip e.g.  16 , and a tether secured to the walker  10  may be tied to the ring  96  to prevent the pin&#39;s  94  loss or misplacement. 
     The clip  16  may be fabricated from a metal, and to increase the frictional force between the clip  16  and the wheelchair  12  horizontal member  18 , a high coefficient of friction post  102 , such as rubber, extends through a hole  100  in the legs  86 ,  88  to deter slippage between the clip  16  and the horizontal chair  12  member  18 . In a second embodiment of the invention, the clip itself  16  may be made of rubber or of a high coefficient of friction plastic to prevent such slippage. 
     The resistance of the walker  10  to instability and sidewards movement may be understood by reference to FIGS. 5 and 6, showing the front caster wheels  100 ,  102  and their swivel mountings. FIG. 5 illustrates one of the caster wheel assemblies, e.g.  100 , consisting of a rubber tired wheel  104  mounted on a swiveling bracket  106 . 
     The off-set end  36 ′ of vertical section  32  is tightly inserted and secured into a cylindrically shaped cup  108 , and hardware consisting of a bolt  109 , washers  110 ,  114  and nut  112  connect the bracket castor wheel assembly  100 , in the following manner. The bolt  109  fits through a hole in the upper surface of a cut-away cylindrical surface stop  116  and through the washers  114 ,  110  such that on tightening the nut  112 , the upper surface of the cut-away cylindrical surface stop  116  is firmly secured against the base of the cup  108  with the concave segment of the surface stop  116  positioned to face in the forward direction of the walker  10 . 
     An oversized hole in the upper surface of the bracket  106  clears the bolt  109  passing through it, and allows the bracket  106  and caster  104  to swivel about the bolt  109 , and accordingly around the vertical member  32 . A low friction spacer  118  attached to the upper surface of the bracket  106  keeps the bracket  106  from binding against the fixed washer  110  during swiveling of caster wheel  104 . 
     The angle through which the caster wheel  104  can swing in either direction, relative to the forward direction of the walker  10 , is limited by the abutment of the swiveling bracket  106  against the fixed vertical edge  122  of the cut-away cylindrical surface stop  116 ; the limit occurring when the caster wheel assembly  100  rotates to the maximum preset angle. The phantomed outlines of the caster wheel assembly  100  seen in bottom view in FIG. 6, shows the abutment of the swivel bracket  106  against the fixed cylindrical surface  116  edges  122 ,  123 . 
     A total swing of 120° relative to the forward direction of the walker  10  allows unimpeded forward motion. At the same time, sideways stability is provided to the walker  10  since non-rolling frictional resistance between the floor and the rubber tired wheels  104 ,  105  to sideways movement of the walker  10  arises when the caster wheel assemblies  100 ,  102  are against the stops  122 ,  123 . 
     This disclosure is provided to reveal a preferred embodiment of the invention and a best mode for practicing the invention. Having thus described the invention in this way, it should be apparent that various different modifications can be made to the preferred embodiment without departing from the scope and spirit of this disclosure. When structures are identified as a means to perform a function, the identification is intended to include all structures which can perform the function specified.