Abstract:
A convertible wheelchair is provided along with a separable lift module for engaging and elevating the convertible wheelchair to a selected elevation. A coupling assembly is operative associated with the lift module and adapted to extend therefrom to where the coupling assembly attaches to the convertible wheelchair. In one embodiment, the coupling assembly comprises a three-point attachment that results in the wheelchair being connected to the coupling assembly and hence the separable lift system at three points. Once coupled to the lift system, the convertible wheelchair, with a patient supported therein, can be raised to a selected elevation. Thereafter, the wheelchair can be converted from a chair configuration to any one of several examination configurations.

Description:
FIELD OF INVENTION 
     The present invention relates to the combination of a convertible wheelchair and a separable and movable lift for the wheelchair. The combination provides a system that enables many medical examinations and procedures to be undertaken without the need of transferring a patient from a wheelchair to an examining table. 
     BACKGROUND OF INVENTION 
     In the conduct of medical or other examinations and therapy for individuals who require a wheelchair for mobility, there arises a need to have the person being examined or treated in a recumbent position and located at a convenient height for the practitioner. While various forms of examination tables are well known, the process of transferring a person from a wheelchair to an examining table can be both uncomfortable and dangerous for the person. Moreover, locations in which examination or treatment of such individuals is desirable, such as private homes, rest homes, and other convalescent or long term care facilities often do not have available the needed examining table. For both of the foregoing reasons, being able to convert a wheelchair to an examining table and being able to use a separate lift to couple to, and raise and lower the wheelchair while it is occupied by the patient provide significant advantages. 
     While wheelchairs which may be converted to horizontal surfaces to permit the recumbency of the occupant exist and are well known. While wheelchairs with devices for raising and lowering exist, such known systems have the disadvantage of a lack of flexibility due to the requirement that the raising and lowering means is integral with the wheelchair. For a better appreciation of the state of the art in this area, one is referred to U.S. Pat. Nos. 4,592,695; 5,179,745; 5,060,960; 4,949,408; 4,119,342; 4,407,543; 4,079,990; 5,050,899; 5,333,887; 5,520,403; and 5,209,322. There remains a need for a system in which any one of a number of convertible wheel chairs can be detachably connected to a separable lift which may be moved from on location to another and which may thereby provide the means for examination and therapy of persons without requiring the particular person to be transferred from the wheelchair to an examination chair or table. 
     SUMMARY OF THE INVENTION 
     The present invention relates to a wheelchair and lift system comprising a convertible wheelchair and a lift module for engaging and detachably connecting to the wheelchair such that the lift module may elevate the wheelchair above a floor or other underlying surface. In one embodiment of the present invention, the lift module is separate from the convertible wheelchair but is adapted to connect to the wheelchair through one or more connecting points. In one particular embodiment, the lift module is provided with a coupling assembly that connects to the wheelchair at three points. In another specific embodiment, the lift module is provided with a coupling assembly that connects to the wheelchair at four points. 
     The present invention also entails a method of examining a person or patient confined to a wheelchair. This method includes rolling the convertible wheelchair over the separate lift module and connecting the lift module to the convertible wheelchair. Then, the lift module is actuated, causing the convertible wheelchair and the patient therein to be elevated above the floor or underlying surface. Thereafter, or in some cases prior to lifting, the wheelchair is converted form a chair configuration to one or more examining configurations. In one embodiment of the present invention, the convertible chair can be converted to an examination table while elevated by the lift module. 
     Other objects and advantages of the present invention will become apparent and obvious from a study of the following description and the accompanying drawings which are merely illustrative of such invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a side view of the wheelchair and separable lift system shown with the wheelchair in a table configuration. 
         FIG. 2  is a perspective view of the wheelchair. 
         FIG. 3  is a side view of the wheelchair. 
         FIG. 4  is a front view of the wheelchair. 
         FIG. 5  is a side view of the lift module and coupling assembly. 
         FIG. 5A  is a fragmentary perspective view of the coupling assembly of the present invention. 
         FIG. 6  is a side elevational view of the convertible wheelchair, with the rear wheels removed, and lift module and illustrates an alternative manner of coupling the wheelchair to the lift module. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     With further reference to the drawings, the wheelchair and lift system of the present invention is shown therein and indicated generally by the numeral  10 . Before discussing the system in detail, it may be noted that the basic system comprises a convertible wheelchair  12 , a separate lift module  14 , and a coupling assembly  18  for interconnecting the wheelchair  12  with the lift module  14 . Wheelchair  12  is adapted to convert from a conventional chair configuration ( FIG. 2 ) to an examination chair or table. In the embodiment illustrated in  FIG. 1 , the convertible wheelchair  12  will convert from a conventional wheelchair configuration to a generally horizontal examination table. In any event, the convertible wheelchair  12  can be rolled over the lift module  14 . Once over the lift module  14 , the coupling assembly  18  attached to the lift module  14  can be extended to and coupled to the wheelchair  12 . Thereafter, the lift module  14  can be actuated, causing the lift module  14  to lift the wheelchair  12 , along with the patient, from an underlying support surface. Once at a selected elevation, the attitude of the person within the wheelchair can be appropriately adjusted by converting the wheelchair  12  to an examination table or simply reclining the back rest of the wheelchair  12  to situate the person therein in a desirable orientation. 
     Referring specifically now to  FIGS. 2 ,  3  and  4 , the wheelchair  12  is schematically shown. As noted above, the wheelchair  12  is a convertible wheelchair inasmuch as the same can be converted from a conventional chair configuration to a table or various other reclining configurations. It should be noted that convertible wheelchairs are known in the art. For example, reference is made to U.S. Pat. No. 4,079,990, the disclosure of which is expressly incorporated herein by reference. With respect to the wheelchair  12  shown in the drawings, in order to better illustrate the frame structure and components of the wheelchair, the upholstered portions of the chair are not particularly shown. However, it is understood that the wheelchair  12  would include various upholstered areas such as is found in conventional wheelchair designs. 
     The fundamental supporting structure of the wheelchair  24  is comprised of a mainframe  20 . Mainframe  20  includes a pair of spaced apart side frames  20   a  that are interconnected together. Each of the side frames  20   a  is of a generally closed rectangular construction. Rear wheels  34  and front casters  32  are conventionally attached to the mainframe  20  and thereby support the mainframe. Rear wheels  34  are adapted to be easily removed from the mainframe by conventional means. This permits easy and direct access to a person or patient supported on the wheelchair when the wheelchair has been converted, for example, to an examination table. 
     Attached to the mainframe  20  is a seat frame or structure  24 . A leg rest  22  is pivotally attached to the mainframe  20  in an area generally above the casters  32 . As will be appreciated from the drawings and from subsequent discussions, the leg rest  22  can be pivotally adjusted to assume various positions with respect to the mainframe  20 . Typically, the pivot joints interconnecting components such as the leg rest  22  with the mainframe  20  include lockable joints. That is, these joints can include a rotary knob that can be turned so as to lock or release the joint. To secure and lock the leg rest  22  in various positions, conventional locking means are provided to lock the leg rest  22  in various positions with respect to the mainframe  20 . To give the leg rest  22  rigidity, the leg rest is provided with a cross member  22   a . Further, pivotally and lockably attached to the leg rest  22  is a foot rest extension  22   b.    
     Pivotally attached to the mainframe  20  in an area generally overlying the rear wheels  34  is a back rest  26 . Back rest  26  includes a number of cross members, including cross member  26   a . As with the leg rest of  22 , the back rest of  26  is provided with conventional means to lock the back rest  26  in various positions with respect to the mainframe  20 . Further, back rest  26  is adapted to receive a removable head rest  28 . The removable head rest  28  includes a pair of terminal ends that are designed to be inserted within sleeves  26   b  mounted to the upper portion of the back rest  26 . 
     Secured to the mainframe  20  just inwardly of the rear wheels  34  are a pair of side frames  30 . Each side frame  30  is pivotally attached the mainframe  20  as shown in FIG.  2 . When an adjacent rear wheel  34  is removed, a side frame  30  can rotate from an upper vertical position to a lower vertical position. Each side frame is provided with a lockable pivot connector  30   a  that permits the side frame  30  to be pivoted through approximately 180° and locked at any position within that range. 
     As discussed briefly above, the wheelchair  12  is designed and adapted to be connected to the lift module  14 . To accommodate this, the wheelchair  12  is provided with a number of connecting links or connecting points. First, in the embodiment shown in  FIGS. 2-4 , there is provided a leg rest connecting link  36 . Connecting link  36  assumes a generally triangular configuration and is pivotally connected to the cross member  22   a  that extends across the leg rest  22 . As seen in  FIG. 2 , link  36  simply projects rearwardly under the seat  24  when the wheelchair  12  assumes its normal chair configuration. There is also provided a back rest connecting link  37 . Back rest connecting link  37  is also of a generally triangular configuration and is pivotally connected to cross member  26   a  of the back rest  26 . Both of the connecting links  36  and  37  include terminal end portions that are designed to be readily connected to the coupling assembly  18  extending from the lift module  14 . 
     Finally, the mainframe  20  is provided with a pair of inwardly projecting stubs  20   b . Stubs  20   b  are of a circular cross section and are secured as cantilever beams projecting inwardly on each side of the side frame members  20   a . As is appreciated from  FIG. 2 , each stub  20   b  includes a retaining section  20   c . As will be appreciated from subsequent portions of the disclosure, stubs  20   a  are instrumental in interconnecting the wheelchair  12  with the lift module  14 . 
     Turning now to lift module  14  and referring specifically to  FIG. 5 , it is appreciated that lift module  14  includes a base  40  which is supported by a series of wheels  44  each of which is provided with a wheel retracting lever and lock of a conventional design. Disposed above and supported by base  40  is housing  46  which is of a generally cylindrical design. Disposed interiorally to and extending upward from housing  46  is armature  48 . Disposed on the base is foot control  50  which conventionally provides means for controlling the vertical position of armature  48 . 
     Details of the lift module  14  are not dealt with herein because such lifting devices are well known and appreciated by those skilled in the art and are commonly incorporated into chairs and examination tables. For example, such a lifting device is incorporated into an examination table manufactured by Ritter Sybron Corporation of Rochester, N.Y. and referred to as the Ritter “75” table. Basically, the Ritter table and other similar tables are powered by an electric motor, hydraulic system, pneumatic system, or a combination of these. 
     As shown in  FIGS. 1 and 5 , a load sensing and readout device  16  is mounted on the upper end of armature  48  in a manner which permits vertical forces transmitted between the armature and structure disposed upon and above the load sensing and readout device  16  to be sensed and indicated on the readout portion of the device. When the lift module  14  is utilized in a doctor&#39;s office, for example, the load sensing and readout device  16  enables the doctor to weigh a patient supported within a wheelchair while coupled to the lift module. 
     Turning now to the coupling assembly  18  and referring in particular to  FIGS. 5 and 5A , coupling assembly  18  includes a base or yoke  60  of a generally “U” shaped construction and having side portions  60   a . The coupling assembly is secured atop load sensing and readout device  16 . Formed in each side portion is a stub receiving slot  60   b . The stub receiving slot comprises a generally horizontal opening extending from one vertical edge of each side portion. At a point somewhat interior to the same vertical edge of the side portion, the slot is abruptly deepened, providing a recessed area. As will be described later, stub receiving slot  60   b  is instrumental in the interconnection of the coupling assembly  18  with the wheelchair  12 . Horizontally disposed slightly above and adjacent to receiving slots  60   b  are locking screw holes  68   a  which are interiorly threaded in a conventional manner and which receive stub retainer shafts  68 . Secured to the outer end of stub retainer shafts  68  are knobs  68   a . As will be appreciated from the description provided later, stub retainer shafts  68  are instrumental in securing stubs  20   b  to side portions  60   a.    
     Continuing to refer to  FIG. 5 , disposed interior to the “U” of yoke  60  and centrally between side portions  60   a  is dual clevis mount  63 . Included in clevis mount  63  are front adjustable link mounting points  62  and rear adjustable link mounting points  64 . A front adjustable link  70  is pivotably attached by a pinned connection to front adjustable link mounting points  62 , and rear adjustable link  72  is pivotably attached by a pinned connection to front adjustable link mounting points  64 . Adjustable links  70  and  72  are of conventional design and include link housings  70   a  and  72   a  and link armatures  70   b  and  72   b . These adjustable links may take the form of hydraulic, pneumatic, or electrical linear actuators. As with the embodiment shown in  FIG. 5 , adjustable links  70  and  72  may also take the form of telescoping assemblies with built-in locking devices  70   d  and  72   d  to fix each link at any particular length within its designed range. Disposed at the distal end of the armature of each adjustable link are link connectors  70   c  and  72   c , of a conventional design and each configured to rigidly and separably attach to one of the connecting links  36  or  37  associated with the wheelchair  24 . 
     Because the lift module  14  is provided with wheels  42 , it follows that the entire lift module can be moved from one location to another location. Prior to using, the lever and lock  44  associated with each wheel is actuated causing the wheels  42  to be retracted. This lowers the base  40  onto an underlying support surface which supports and stabilizes the lift module  14 . Alternatively, the support surface can be adapted to include a structure that would couple directly to the base  40  of the lift module. This structure would positively retain and stabilize the lift module  14 . 
     To position the lift module  14  to receive and elevate the wheelchair  24 , the armature  48  of the lift module is adjusted using the foot control  50  to a position where the stub receiving slots  60   b  are horizontally aligned with the stubs  20   b  of the wheelchair  24 . Stub retainer shafts  68  are retracted so that the deepened ends of the stub receiving slots  60   b  are unobstructed. 
     Wheelchair  12 , with occupant (not shown), is then caused to move horizontally towards lift system  14  such that stubs  20   b  engage stub receiving slots  60   b . Movement of wheelchair  12  continues until stubs  20   b  reach the deepened ends of slots  60   b  at which point the horizontal movement of the wheelchair is stopped. To secure stubs  20   b  in slots  60   b , armature  48  is caused to move upward sufficiently to cause stubs  20   b  to rest entirely within the deepened areas of slots  60   b . Using knobs  68   a , stub retainer shafts  68  are positioned so that they span the deepened area of slots  60   b  and secured stubs  20   b  from uplift that may be caused by side loads or tilting moments. 
     As can be appreciated from a study of  FIGS. 1 and 5 , armature  70   b  of front adjustable link  70  is adjusted in length as required and is connected to legrest lift connecting link  36  using connector  70   c . Similarly, armature  72   b  of rear adjustable link  72  is adjusted in length as required and is connected to backrest connecting link  37  using link connector  72   c . These connections provide that legrest connecting link  36  and backrest connecting link  37  function as rigid extensions of armatures  70   b  and  72   b , respectively. The pivotable connections between footrest  22   b  and legrest  22 , legrest  22  and mainframe  20 , and main frame  20  and backrest  26  remain locked to maintain the wheelchair in the chair configuration. Using foot control  50  to control the vertical movement of armature  48 , wheelchair  12  is then elevated to the desired height. After attaining the desired height for the wheelchair, either or both of the rear wheels  34  are removed and either or both of sidearms  30  are unlocked and pivoted outwardly and then downwardly such that they are disposed outside main frame  20 . 
     The process of converting the wheelchair to a table then follows. First, while keeping the pivotable connection between main frame  20  and backrest  26  locked, the pivotable connection between legrest  22  and main frame  20  is released. Front adjustable link  70  is then unlocked and extended, thereby causing legrest  22  to rotate in a counterclockwise fashion, as viewed in FIG.  1 . Upon attaining a horizontal position of legrest  22 , the pivotable connection between legrest  22  and main frame  20  is locked. The pivotable connection between footrest  22   b  and legrest  22  may them be unlocked, the footrest positioned horizontally, and the connection relocked. In preparation for adjusting backrest  26  in a similar fashion, headrest  28  is removed from backrest  26 , rotated 180 degrees about the vertical, and reattached to backrest  26 . The pivotable connection between backrest  26  and main frame  20  is then released. Rear adjustable link  72  is then unlocked and extended, thereby causing backrest  26  to rotate in a counterclockwise fashion, as viewed in FIG.  1 . Upon attaining a horizontal position of backrest  26 , the pivotable connection between backrest  26  and main frame  20  is locked. As can be appreciated particularly from  FIG. 1 , the foregoing adjustments render the wheelchair  12  in a table configuration. As can be further appreciated by one of ordinary skill in the art, other configurations can be produced by separately adjusting, one at a time, the orientations of legrest  22  and backrest  26  generally following the above procedures. 
     The steps described above are retraced in reverse order to reconfigure the wheelchair  24  to a chair configuration. Once the wheelchair  24  has been reconfigured to a chair configuration, the wheelchair  24  can be lowered to the floor or underlying support structure, and thereafter the wheelchair can be detached from the lift module  14 . 
     Turning now to  FIG. 6 , an alternate embodiment of the present invention is shown therein. In this alternate embodiment the structure and operation of the lift module  14  remains the same and further the basic structure of the wheelchair  12  remains the same as described before. However, in this embodiment, the coupling assembly  18  is designed to couple directly to the mainframe  20  of the wheelchair  24 . In particular, the stubs  20   b  couple to the base or yokes  60  in the same way as discussed above and as illustrated in FIG.  1 . However, in the alternate design of  FIG. 6 , the coupling assembly  18  is provided with a clevis  80  that extends rearwardly from the base or yoke  60 . A single connecting link  90  is interconnected between the clevis  80  and a connecting clevis  82  on the mainframe  20  of the wheelchair  24 . The connecting link  90  includes and extendable link  92   a  that enables the connecting link as a whole to be adjustably connected between the clevis  80  and the connecting clevis  82  on the mainframe  20 . Once the coupling assembly  18  is appropriately connected to the wheelchair  24 , the lift module  14  can be actuated, causing the wheelchair  24  to be elevated as shown in FIG.  6 . At this point, the backrest  26  and the leg rest  22  can be adjusted in the same manner described above. 
     The present invention has numerous uses and advantages. Seriously disabled patients confined to a wheelchair can be examined in a doctor&#39;s office without having to be removed from the wheelchair and placed on a conventional examination table. Likewise, the system of the present invention has utility in nursing homes and rest homes where patients have to be routinely examined by doctors or attending staff. Further, the present invention can be utilized in transferring a disabled patient from a wheelchair to a bed, whether it be in a hospital, nursing home, rest home or other medical care facility. A system such as that described herein is particularly useful in cases where patients have very delicate and fragile skin that is susceptible to bruising and tearing. In the end, the present system will enable these patients to be examined and even moved from a wheelchair to a bed with minimum handling. 
     The present invention may, of course, be carried out in other specific ways than those herein set forth without departing from the scope and the essential characteristics of the invention. The present embodiments are therefore to be construed in all aspects as illustrative and not restrictive and all changes coming within the meaning and equivalency range of the appended claims are intended to be embraced therein.