Convertible wheelchair and separate lift module for connecting to and elevating the wheelchair

[00002] 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.

[00003] 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.

[00004] 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.

[00005] 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.

[00006] 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.

[00007] 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.

[00015] 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.

[00016] 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.

[00017] The fundamental supporting structure of the wheelchair 24 is comprised of a mainframe 20. Mainframe 20 includes a pair of spaced apart side frames 20a that are interconnected together. Each of the side frames 20a 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.

[00018] 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 22a. Further, pivotally and lockably attached to the leg rest 22 is a foot rest extension 22b.

[00019] 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 26a. 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 26b mounted to the upper portion of the back rest 26.

[00020] 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 30a that permits the side frame 30 to be pivoted through approximately 180° and locked at any position within that range.

[00021] 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 22a 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 26a 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.

[00022] Finally, the mainframe 20 is provided with a pair of inwardly projecting stubs 20b. Stubs 20b are of a circular cross section and are secured as cantilever beams projecting inwardly on each side of the side frame members 20a. As is appreciated from FIG. 2, each stub 20b includes a retaining section 20c. As will be appreciated from subsequent portions of the disclosure, stubs 20a are instrumental in interconnecting the wheelchair 12 with the lift module 14.

[00023] 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.

[00024] 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.

[00025] 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'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.

[00026] 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 60a. The coupling assembly is secured atop load sensing and readout device 16. Formed in each side portion is a stub receiving slot 60b. 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 60b is instrumental in the interconnection of the coupling assembly 18 with the wheelchair 12. Horizontally disposed slightly above and adjacent to receiving slots 60b are locking screw holes 68a 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 68a. As will be appreciated from the description provided later, stub retainer shafts 68 are instrumental in securing stubs 20b to side portions 60a.

[00027] Continuing to refer to FIG. 5, disposed interior to the “U” of yoke 60 and centrally between side portions 60a 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 70a and 72a and link armatures 70b and 72b. 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 70d and 72d 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 70c and 72c, 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.

[00028] 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.

[00029] 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 60b are horizontally aligned with the stubs 20b of the wheelchair 24. Stub retainer shafts 68 are retracted so that the deepened ends of the stub receiving slots 60b are unobstructed.

[00030] Wheelchair 12, with occupant (not shown), is then caused to move horizontally towards lift system 14 such that stubs 20b engage stub receiving slots 60b. Movement of wheelchair 12 continues until stubs 20b reach the deepened ends of slots 60b at which point the horizontal movement of the wheelchair is stopped. To secure stubs 20b in slots 60b, armature 48 is caused to move upward sufficiently to cause stubs 20b to rest entirely within the deepened areas of slots 60b. Using knobs 68a, stub retainer shafts 68 are positioned so that they span the deepened area of slots 60b and secured stubs 20b from uplift that may be caused by side loads or tilting moments.

[00031] As can be appreciated from a study of FIGS. 1 and 5, armature 70b of front adjustable link 70 is adjusted in length as required and is connected to legrest lift connecting link 36 using connector 70c. Similarly, armature 72b of rear adjustable link 72 is adjusted in length as required and is connected to backrest connecting link 37 using link connector 72c. These connections provide that legrest connecting link 36 and backrest connecting link 37 function as rigid extensions of armatures 70b and 72b, respectively. The pivotable connections between footrest 22b 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.

[00032] 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 22b 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.

[00033] 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.

[00034] 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 20b 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 92a 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.

[00035] The present invention has numerous uses and advantages. Seriously disabled patients confined to a wheelchair can be examined in a doctor'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.

[00036] 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.