Abstract:
A convertible wheeled chair is easily changed by an attendant into a gurney of the same height as a patient bed. During the process of transferring a patient from an upright position to a reclining position, convertible wheeled chair shifts the center of gravity of the patient rearwardly, and therefore does not give the patient a sensation of sliding from the chair.

Description:
This nonprovisional patent application claims priority from provisional patent application Ser. No. 60/656,033, filed Feb. 24, 2005, entitled Mobile Transport Device, which provisional application is incorporated herein by reference in its entirety. 

   FIELD OF THE INVENTION 
   The present invention generally relates to patient chairs and, more particularly to reclinable wheeled chairs which may be used to transfer a patient to a bed or from a bed to the wheeled chair. 
   BACKGROUND OF THE INVENTION 
   There are more than twenty-five million citizens in the United States who are temporarily or permanently totally disabled. These people reside in nursing homes, hospitals, rehabilitation facilities or in homes where they are totally dependent upon the care of others for their survival. Many of these people suffer from obesity and are unable to assist or only partially assist in their own care or handling. Many are confined to bed unless removed from their beds by attending persons. The typical method of removing a disabled person from a bed is to raise the disabled person to a sitting position, rotate the patient to a sitting position on the side of the bed and with an attendant under each arm and an attendant standing and facing the patient, stand or pick the patient up and then turn and lower the patient into a chair, wheelchair, geriatric chair, or on to some other conveying mechanism. The increase in such patients that are in excess of three hundred pounds in body weight has greatly exacerbated the foregoing methodology. 
   The result of physically handling disabled and obese persons is that many sustain spontaneous bone fractures, muscle and ligament pulls or tears, or pain solely from the physical handling and lifting. Another direct consequence of the existing practice outlined above is that the attendants suffer high incidents of injuries to their backs, muscles or ligaments as a result of physically lifting disabled, obese persons from sitting positions onto beds and returning them to their sitting positions. This consequence usually requires that institutions pay the highest workman&#39;s compensation insurance rates, and are required to hire additional attendants to perform the lifting and handling of disabled persons. In the home environment the consequence is that the disabled person is essentially confined to bed. 
   Thus, the problem is that millions of disabled obese persons in institutions or at home are being moved from beds to chairs or other appliances by the physical strength of their attendants with resulting injuries both to the patient and attendants; or the patient is never or seldom moved from the bed, with resulting bed sores, bad hygiene and circulatory problems. Such problems have greatly increased the cost of care of disabled persons through high insurance costs, additional labor, injuries and litigation. 
   Combined chair and gurney systems are well known in the art. For example, U.S. Pat. No. 2,587,068 shows a combined chair and gurney which is convertible from a chair to a gurney at the same height as a bed or operating table for transfer if desired. A frame supporting the patient is mounted for pivotal movement between various positions on a lower support frame mounted between wheels or casters. The seat supporting the patient remains in a horizontal position at all times and can not be inclined. Also, side frames are not provided alongside the seat at all times for support of the patient. 
   U.S. Pat. No. 3,147,039, shows a combined wheelchair and gurney which is convertible for transport of a patient either in a sitting or lying position. A pair of side frames are provided to support a linkage for converting the transportation of a patient between a sitting position and a lying position. The back seat frame and the leg seat frame are both connected to and supported by the opposed side frames, and the seat frame remains positioned horizontally at all times. 
   U.S. Pat. No. 4,717,169, discloses the concept of a wheeled structure that is readily convertible between a full-sized bed and a wheelchair. This is different from the teachings of the present invention in that the unit does not include any mechanism to facilitate a rearward shifting of the patient&#39;s center of gravity, or transferring the patient from the bed arrangement onto another like bed. 
   U.S. Pat. No. 4,787,104, discloses the concept of a convertible hospital bed that includes mechanism to assist moving a patient that is in the bed into a sitting position and off the bed. These teachings are only generally related to the present invention, and fail to include a wheelchair unit that is convertible into a gurney or the concept of a rearward shift of a patient&#39;s center of gravity. 
   U.S. Pat. No. 4,821,352, discloses an arrangement combining a wheelchair with a bed, wherein the bed has mechanism that assists in lifting an invalid from the bed into a wheelchair with the wheelchair having a mechanism to receive the invalid from the bed. The wheelchair unit is different from that of the present invention since it fails to include structures which include any mechanism to facilitate a rearward shift of the patient&#39;s center of gravity, or permit transfer of an invalid between a bed and a convertible wheelchair, where the convertible wheelchair is located adjacent the side of the bed. 
   Reclinable wheeled chairs are also known in the art, for example, U.S. Pat. Nos. 1,748,784; 2,587,068; 2,682,913; 2,694,437; 2,869,614; 2,913,738; 3,147,039; 3,284,093; 3,344,445; 3,406,772; 3,967,328; 4,190,913; 4,255,823; 4,285,541; 4,361,917; 4,381,571; 4,432,359; 4,453,732; 4,717,169; 4,726,082; 4,787,104; 4,839,933; 4,856,123; 4,858,260; 4,966,379; 4,997,200; 5,048,133; 5,971,482; 5,996,716; 6,003,891; and 6,158,810 disclose various wheeled chairs, many of which focus shifting the orientation of a patient from a seated position to a supine or prone position to aid in patient care. These prior art wheeled chairs provide transportation and mobility to patients, while allowing the patient to recline to a prone position for comfort. Although conventional wheeled chairs provide the above-mentioned features, conventional wheeled chairs have limited capabilities. 
   For example in many of the foregoing prior art devices the process of transitioning a patient from an upright, seated position to a supine, prone position relies upon a seat structure that relies upon a “parallelogram” linkage to effect the transition. Since the length relationship among the links always remains a constant during operation of such prior art “parallelogram” linkage-based seats, a shift in the center of mass of the patient outwardly very often results, giving the patient a sensation of sliding from the chair. This sensation is disconcerting to the obese patient, and thus often requires more than one caregiver, and great effort by the patient, to maintain the patient&#39;s sense of safety during transition from sitting to reclining or vice-a-versa. 
   What is needed in the art is a wheeled chair, which provides a simple, safe, and cost-effective way of transitioning a patient from an upright, seated position to a supine, prone position and vice versa. What is also needed is a wheeled chair and gurney combination, which simplifies the patient transfer process and enhances the safety of that process. 
   SUMMARY OF THE INVENTION 
   The present invention provides a convertible wheeled chair that is easily changed by an attendant into a gurney of the same height as a patient bed. During the process of transferring a patient from an upright position to a reclining position, the present invention shifts the center of gravity or mass of the patient rearwardly, and therefore does not give the patient a sensation of sliding from the chair. Also the present invention may be tilted or reclined backward so as to provide for increased blood flow to the upper regions of the patient&#39;s body during initial treatment of trauma. 
   In one embodiment, a convertible chair is provided that is adapted to be transformed from a first position suitable for supporting a seated patient to a second position suitable for supporting reclining patient at the same height as a patient bed. The convertible chair includes a pair of spaced-apart side frames and a back frame including a pair of spaced-apart support members each having an axially off-set extension located at a bottom end. A seat frame is pivotally supported upon the pair of spaced-apart side frames. The seat frame includes a pair of spaced-apart telescoping beams arranged in substantially parallel relation to the pair of spaced-apart side frames. Each of the telescoping beams has a front end and a rear end, and is capable of changing length. Each of the front ends is pivotally mounted upon a portion of an adjacent side frame, and each of the rear ends is pivotally mounted upon a portion of a respective one of the axially off-set extensions. A pair of spaced-apart lower link beams each has a front end and a rear end that are each pivotally engaged with a respective one of the telescoping beams by a front toggle beam and a rear toggle beam, respectively. A powered drive is operatively supported between the pair of spaced-apart side frames and operatively engaged with the seat frame so as to move the seat frame and the back frame between (i) a first position where the seat frame and the back frame are oriented so as to be suitable for supporting a seated patient. In this position, the telescoping beam is at its shortest length. Additionally, the powered drive operatively engages the seat frame so as to move it to a second position where the seat frame and the back frame are oriented so as to be suitable for supporting a reclining patient at the same height as a patient bed. In this position, the telescoping beam is at its longest length. 
   The convertible chair is designed to allow a disabled patient to be slipped or turned from the surface of a bed onto the convertible wheeled chair in its gurney position, then gently lowered into an infinitely adjustable sitting and/or reclining position. When the disabled person has medical, physical, or hygienic needs, the attendant simply and easily raises the disabled person to the horizontal gurney position, attends to those needs, and then simply and easily lowers the patient to a desired sitting or reclining position. 
   Patients benefit from use of the convertible wheeled chair because they are never physically lifted by attendants with the possible resulting injuries, and the patients can be kept much cleaner because of the ease and frequency with which they can be administered. In addition, patients benefit because they frequently move, thereby eliminating pressure points which cause bed sores. A post-operative patient also benefits from the changing sitting/reclining/horizontal positions in that the circulatory system of the patient is exercised by a frequent, yet gentle movement. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     These and other features and advantages of the present invention will be more fully disclosed in, or rendered obvious by, the following detailed description of the preferred embodiment of the invention, which is to be considered together with the accompanying drawings wherein like numbers refer to like parts and further wherein: 
       FIG. 1  is a perspective view of a mobile transport device formed in accordance with the present invention; 
       FIG. 2  is a perspective view of the mobile transport device shown in  FIG. 1  having portions of the super structure removed for clarity of illustration; 
       FIG. 3  is an exploded, perspective view of a telescoping beam assembly formed in accordance with the present invention; 
       FIG. 4  is an exploded, perspective and broken-away view of a portion of the telescoping beam assembly shown in  FIG. 3 ; 
       FIG. 5  is a perspective broken-away portion of a seat frame and back frame formed in accordance with the present invention; 
       FIG. 6  is a broken-away and partially cross-sectional side elevational view of the portions of the back frame and seat frame shown in  FIG. 5 ; 
       FIG. 7  is a broken-away and partially cross-sectional view similar to  FIG. 6  showing a telescoping beam assembly in operation during the movement of a back frame in accordance with the present invention; 
       FIG. 8  is a broken-away and partially cross-sectional view similar to  FIGS. 6 and 7  further illustrating the actuation of the present invention; 
       FIG. 9  is a side elevational view of the mobile transport device formed in accordance with the present invention; 
       FIG. 10  is a side elevational view of the mobile transport device formed in accordance with the present invention, in a supine position; and 
       FIG. 11  is a side elevational view of a mobile transport device similar to that shown in  FIG. 10 , in a tilted position. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   This description of preferred embodiments is intended to be read in connection with the accompanying drawings, which are to be considered part of the entire written description of this invention. The drawing figures are not necessarily to scale and certain features of the invention may be shown exaggerated in scale or in somewhat schematic form in the interest of clarity and conciseness. In the description, relative terms such as “horizontal,” “vertical,” “up,” “down,” “top” and “bottom” as well as derivatives thereof (e.g., “horizontally,” “downwardly,” “upwardly,” etc.) should be construed to refer to the orientation as then described or as shown in the drawing figure under discussion. These relative terms are for convenience of description and normally are not intended to require a particular orientation. Terms including “inwardly” versus “outwardly,” “longitudinal” versus “lateral” and the like are to be interpreted relative to one another or relative to an axis of elongation, or an axis or center of rotation, as appropriate. Terms concerning attachments, coupling and the like, such as “connected” and “interconnected,” refer to a relationship wherein structures are secured or attached to one another either directly or indirectly through intervening structures, as well as both movable or rigid attachments or relationships, unless expressly described otherwise. The term “operatively connected” is such an attachment, coupling or connection that allows the pertinent structures to operate as intended by virtue of that relationship. In the claims, means-plus-function clauses, if used, are intended to cover the structures described, suggested, or rendered obvious by the written description or drawings for performing the recited function, including not only structural equivalents but also equivalent structures. 
   Referring to  FIGS. 1–4 , the present invention provides a mobile transport device  2  that is convertible between a chair in which a patient may be arranged in a seated position and a tiltable gurney with the patient in a supine or prone position. Mobile transport device  2  includes a pair of side frames  4 , a back frame  6 , a seat frame  8 , a transport frame  10  and powered drive assemblies  12 . More particularly, each side frame  4  includes a two spaced-apart vertical support members  15  and two spaced-apart transverse support members  16  joined at their respective ends so as to form an open frame. One or more vertical beams  18  may extend between spaced-apart transverse support members  16  so as to provide structural integrity sufficient to support the weight of a three hundred pound to six hundred pound patient. Arm rests  20  are positioned atop upper ones of the spaced-apart transverse support members  16 . A pivot joint  24  is located in each lower rear corner of each side frame  4  and arranged in confronting, coaxial relation to one another (FIGS.  2  and  9 – 11 ). 
   Back frame  6  includes two spaced-apart vertical support members  30  and a plurality of spaced-apart transverse support members  32  that are arranged in parallel spaced relation to one another between vertical support members  30 , and are joined at their respective ends to portions of vertical support members  30 . An axially off-set extension beam  33  ( FIG. 6 ) is arranged adjacent to each bottom end  35  of each vertical support members  30  ( FIGS. 6 ,  7 , and  8 ). A transverse pivot hole  36  is located in each off-set extension beam  33 . Pivot holes  36  are arranged in confronting, coaxial relation to one another. Off-set extension beams  33  are preferably arranged on end portions  35  of vertical support members  30  so as to extend outwardly at an angle Θ of between about 5° and about 12° from the longitudinal axis of vertical support members  30 . 
   Referring to  FIGS. 2–8 , seat frame  8  is positioned between side frames  4  and at the lower end of back frame  6 , and includes a pair of spaced-apart telescoping beam assemblies  40 , a pair of spaced-apart lower link beams  41 , and a pair of toggle beams  42  ( FIG. 5 ). Each telescoping beam assembly  40  includes a hollow support tube  46 , a slide tube  48 , a tubular journal  50 , and a plug  52 . Hollow support tubes  46  include a transverse pivot hole  54  adjacent to a front end  56  and spaced-away from a back end  57 . Hollow slide tube  48  has an outer diameter that is smaller than the internal diameter of both tubular journal  50  and hollow support tube  46 , while tubular journal  50  has an outer diameter that is slightly smaller than the internal diameter of hollow support tube  46 . Slide tube  48  includes a front end opening  59  and a back end  58 , and includes a transverse pivot hole  60  adjacent to a back end  58 . Tubular journal  50  includes an annular lip  62  disposed at one end that has an outer diameter that is larger than the internal diameter of hollow support tube  46 . In this way, slide tube  48  can be slidingly positioned within tubular journal  50 , and both can be received at back end  57  of hollow support tube  46  so that slide tube  48  can be slid axially within hollow support tube  46  guided by tubular journal  50 . Plug  52  includes an annular lip  65  disposed at one end that has an outer diameter that is larger than the internal diameter of slide tube  48 , but smaller than the internal diameter of hollow support tube  46 , and is positioned in front end opening  59  of slide tube  48 . 
   Each lower link beam  41  comprises a rod having a front end  68 , a rear end  70 , and a pair of spaced-apart transverse pivot holes  72 ,  73  located adjacent to front end  68  and rear end  70 , respectively. Lower link beam  41  is often hollow, and has a length that is approximately equal to the fully contracted length of telescoping beam assembly  40 . Front toggle beam  42  and rear toggle beam  43  are nominally shorter than either lower link beam  41  or a fully contracted telescoping beam assembly  40 , and each include spaced-apart transverse pivot holes  75 ,  76 . 
   A mobile transport device  2  may be assembled and operated in the following manner. Transport frame  10  supports side frames  4  and back frame  6 , and includes three or four wheels  78 . A pair of coaxial, spaced-apart pivot holes  80  are located in the rear portion of frame  10 . A pivot bracket  82  that is fixed in a rear portion of lower transfer support member  16  of side frames  4  pivotally fastens side frames  4  to transport frame  10  via a pivot pin  84 . In this way, the chair/gurney portion of mobile transport device  2  can be tilted rearwardly about pivot pin  84  so as to be approximately 15° relative to transport frame  10  ( FIGS. 10 and 11 ). 
   To convert mobile transport device  2  from a chair to a gurney, seat frame  8  is driven by drive assembly  12  in the form of an electric motor (not shown) that engages a portion of lower link beam  41 . It will be understood that while mobile transport device  2  is arranged in an upright position that is suitable for supporting a seated patient, the telescoping beam assembly  40  resembles a parallelogram ( FIG. 5 ). However, as lower link beam  41  is moved forwardly, front toggle beam  42  and rear toggle beam  43  pivot about pivot holes  72 ,  73  and  60 . As this occurs, telescoping beam assemblies  40  lengthen relative to link beam  41 , changing the shape of telescoping beam assembly from substantially a parallelogram to substantially non-parallelogram in shape. More particularly, hollow support tube  46  is drawn away from slide tube  48  such that lip  65  of plug  52  moves along the internal surface of hollow support tube  46 . Advantageously, since the structure of seat frame  8  does not remain in a parallelogram shape, due to the growth in length of telescoping beam assemblies  40 , the angular axial offset of extension  33  at the bottom end  35  of vertical support members  30  provides for a shifting of the center of gravity of the person seated in mobile transport device  2  rearwardly so as to provide a comfortable, non-sliding sensation to that person as they transition from a seating position to a reclining, supine or prone position on mobile transport device  2 . 
   It is to be understood that the present invention is by no means limited only to the particular constructions herein disclosed and shown in the drawings, but also comprises any modifications or equivalents within the scope of the claims.