Abstract:
A wheelchair for use in care facilities includes a seat lift mechanism and a chair tilt mechanism both of which are actuated by a single lever. Operation of the lever elevates the rear of the seat and raises the rear of the wheelchair thereby moving the wheelchair occupant toward a standing position and reduces the lifting effort of the attendant in assisting the debilitated patient to move out of the wheelchair.

Description:
CROSS REFERENCE TO CO-PENDING PROVISIONAL APPLICATION 
     This application [is converted from] claims the benefit under 35 U.S.C. §119(e) and 37 C.F.R. §1.78 of copending provisional patent application entitled “Ergonomic Wheelchair with Patient Lifting Mechanism”, Ser. No. 60/191,081 filed Mar. 21, 2000.[, from which this application claims priority.] 
    
    
     BACKGROUND OF THE INVENTION 
     Wheelchairs are used to move patients within hospitals and nursing homes. Current wheelchairs are constructed with a seat and seat back supported on a rectangular frame with large rear wheels and small front wheels which may swivel. Typically a brake mechanism is employed with each back wheel to prevent its rotation when the patient is to be removed from the wheelchair. When a patient who is seated in a wheelchair is to be moved to a stationary chair or a bed, an attendant must stand in front of the patient to lift the patient to assist the patient in leaving the wheelchair. The attendant must reach forward and grasp the arms or body of the patient to lift the patient from the wheelchair even when the patient can assist by standing. The lifting activity must be performed while the attendant is in a weakened position, leaning forward and bending down, and this frequently contributes to back injuries of the attendant. 
     SUMMARY OF THE INVENTION 
     The present invention is an improved wheelchair for transporting patients, especially elderly and feeble patients living in nursing homes where movement of patients to and from wheelchairs is a frequent occurrence. The improved wheelchair of the present invention provides an ergonomic improvement in the job responsibilities of the attendant who must assist the debilitated patient in moving from the wheelchair to another position. Hence it is an object of the invention to provide a wheelchair which reduces the risk of back injury to the attendant assisting the patient in leaving the wheelchair. 
     The wheelchair is provided with a main frame supported on four generally equally sized wheels, the rear two of which are pivotable on a vertical axis in the typical fashion. A seat supporting frame on which the seat of the wheelchair is supported is carried within the main frame. The seat supporting frame is hinged along its front-to-back length such that the rear end of the seat can be raised when the patient is to exit the wheelchair. As the rear end of the seat rises, the front end of the seat lowers. This operation is effected by use of an operating lever which turns a transverse bar to which a seatlift lever is radially attached. The seatlift lever is connected to a link which forces the rear of the wheelchair seat upward. A lifting mechanism which raises the rear of the wheelchair frame is also operable when the operating lever is actuated. This lifting mechanism causes a foot to be lowered below the rear of the wheelchair frame and forced against the floor surface on which the wheelchair is stationed. This operation also causes the rear wheels of the wheelchair to be lifted off the floor surface, thereby also elevating the patient&#39;s body within the wheelchair while immobilizing the wheelchair. The foot is fixed to the lower end of a generally vertical stake which is guided by a bushing it passes through, the bushing being held stationary relative to the chair by its mounting to a cross bar mounted at its ends to the wheelchair&#39;s main frame. The stake is forced downward by a linking arm which rotates with the rotatable transverse bar to which the operating lever is fixed. Hence, pulling the operating lever toward the front of the wheelchair causes the rear of the wheelchair frame to elevate off the floor surface while also causing the seat to tilt forward thereby assisting the patient toward a standing position. With the patient partly elevated, an attendant need not stoop forward to help in lifting and guiding the patient from the wheelchair. 
     In an alternate embodiment, the wheelchair may include a rider operated lever so that the occupant of the chair can activate the lift mechanism. In another embodiment, the lift mechanism may be operated by a person behind the chair by use of a rearward moving lever. 
     It is an object of the invention to provide an improved wheelchair which selectively lifts a patient seated in the wheelchair part way to a standing position. 
     It is another object of the invention to provide a wheelchair which may be immobilized while a patient is being removed from the chair. 
     It is further an object of the invention to provide an improved wheelchair which reduces the risk of back injury to an attendant assisting a patient in exiting the wheelchair. 
     These and other objects will be better understood from examination of the detailed description which follows. 
    
    
     DESCRIPTION OF THE DRAWING FIGURES 
     FIG. 1 is a front right perspective of a wheelchair according to the present invention. 
     FIG. 2 is a side elevation of the wheelchair of FIG. 1 in its travel position. 
     FIG. 3 is a side elevation of the wheelchair of FIG. 1 in its elevated position. 
     FIG. 4 is a side elevation of the wheelchair invention in its elevated position with the left frame components removed and with the activation lever partly cut away. 
     FIG. 5 is a rear view of the wheelchair in its travel position. 
     FIG. 6 is a section view along line  6 — 6  of FIG.  5 . 
     FIG. 7 is a side elevation of an alternative embodiment wheelchair provided with a rider-operable lever. 
     FIG. 8 is a side elevation of another alternative embodiment wheelchair provided with an attendant-operable lever which may be operated from behind the wheelchair, the wheelchair shown in its elevated position. 
     FIG. 9 is an enlarged perspective view of the elevating linkage of the alternate embodiment wheelchair of FIG.  8 . 
     FIG. 10 is a side elevation of a third alternate embodiment wheelchair shown in its elevated position with the rear wheels rotated forward from their travel position behind the rear legs of the wheelchair frame. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     This invention is a wheelchair for transporting persons around residential care facilities for the elderly and disabled. Like elements are identified by identical reference characters throughout the drawing figures. 
     FIG. 1 depicts a front right perspective of the invention wheelchair  2  in its travel position wherein a person who may be seated in the wheelchair  2  may be moved from one location to another. Wheelchair  2  is provided with a main frame  4  including vertical legs  6 ,  8 ,  10 ,  12  at each of the corners of main frame  4 . The main frame  4  supports a pivotable seat frame  14  therewithin, the seat frame  14  having a seat  16  mounted thereupon. A horizontal strut  86  interconnects front legs  6  and  8  and is disposed spaced apart from and below seat frame  14 . A backrest  18  is mounted to the upper ends  20 ,  22  respectively of rear legs  10 ,  12 . Arm rests  24 ,  26  may extend from upper ends  20 ,  22  to provide lateral arm support for a patient seated in wheelchair  2 . Handles  30 ,  32  extend rearwardly from upper ends  20 ,  22  of rear legs  10 ,  12  respectively, to provide grips for an attendant to push the wheelchair  2  and guide it as desired. The wheelchair  2  is supported by paired rear wheels  72  and front wheels  74 . Rear wheels  72  are mounted by stem housings  76  fixed to the rear of rear legs  10 ,  12  such that each of rear wheels  72  may freely rotate about a vertical axis defined by the stem housings  76 . Each of front wheels  74  is mounted to one of front legs  6 ,  8  but front wheels  74  do not swivel about a vertical axis. An elongate lever  28  having a lower end  34  is mounted at its lower end  34  to transverse bar  36  which extends laterally below seat  16  immediately in front of rear legs  10  and  12 . Lever  28  is provided with grip handle  68  at its upper free end  70 . Transverse bar  36  is rotatable about its axis and is retained to rear legs  10 ,  12  by bearing housings  60  into which the opposing ends of transverse bar  36  are journaled. Transverse bar  36  is fixed to lower end  34  of lever  28  such that rotation of lever  28  about its lower end  34  will cause axial rotation of transverse bar  36 . 
     Referring now to FIGS. 2-6, other details of the structure of wheelchair  2  may be visualized. Seat frame  14  is pivotable upon main frame  4  about a pair of hinge pins  38  which are journaled by bushings  92  to the undersides of opposing sides  40 ,  42  of main frame  4 . Each hinge pin  38  is oriented with its axis horizontal. Because of the pivotal mounting of seat frame  14  to main frame  4  at a point between the front end  44  and rear end  46  of seat frame  14 , but not necessarily midway therealong, the front  48  of seat  16  may decline while the rear  50  thereof rises. Hinge pins  38  are disposed about thirty to forty percent, preferably approximately thirty-five percent, of the distance from front end  44  to rear end  46  of seat frame  14 . Pivot of seat frame  14  is accomplished by operation of lever  28 , which also causes downward movement of stake  52  which engages the floor surface  64  to elevate the rear legs  10 ,  12  of wheelchair  2 . Specifically, as lever  28  is moved forward from its substantially upright rest position, transverse bar  36  rotates about its axis, causing rotation of stake arm  54  and of seatlift lever  56 , each of which is radially fixed to transverse bar  36 . The angular displacement of seatlift lever  56  causes upward movement of link arm  58  which interconnects bracket  78  on seat frame  14  and the free end  62  of seatlift lever  56 . As transverse bar  36  is rotated, stake arm  54  rotates counterclockwise forcing stake  52  downward causing foot  88  thereof to come into touching engagement with the floor surface  64  under the wheelchair  2 . Foot  88  is elongate laterally and is provided with skid-resistent pads  90  on the underside of the ends thereof. Cross bar  80  is supported on lateral arms  82 ,  84  extending a few inches forward of rear legs  10 ,  12  respectively and is disposed generally in parallel to transverse bar  36  and generally vertically aligned with free end  55  of stake arm  54  when stake arm  54  is horizontally oriented. Stake  52  is guided through bearing tube  66  mounted along cross bar  80 . As stake  52  is forced downward through bearing tube  66  of cross arm  80 , front wheels  74  and rear legs  10 ,  12  are elevated, thus raising the rear of main frame  4  of wheelchair  2 . 
     Illustrated in FIG. 7 is an alternative embodiment of the invention wherein wheelchair  102  is equipped with rider-operable lever  128  which may be provided on each side of main frame  4 , such that a rider seated in wheelchair  102  may self operate the lifting mechanism as described in reference to FIGS. 1-6. Rider-operable lever  128  is fixed at its lower end  134  to transverse bar  36  such that forward and downward movement of rider-operable lever  128  will cause axial rotation of transverse bar  36  thereby causing link  58  to urge seat frame  14  to rotate about hinge pins  38 . Because stake arm  54  is radially fixed to transverse bar  36 , stake arm  54  also rotates about the axis of transverse bar  36  and urges stake  52  downward into abutting engagement with floor surface  64 , thereby raising rear wheels  72  above floor surface  64  while front wheels  74  remains resting on floor surface  64 . Rider-operable lever  128  includes a first segment  130  which includes lower end  134  which is fixed to transverse bar  36 . Mounted angularly to the upper end  132  of first segment  130  is second segment  126  which may be provided with a transverse hand grip  136  at its free end  124 . Second segment  126  is disposed generally parallel to arm rest  26  when wheelchair  102  is in its travel position. A rider seated in wheelchair  102  may grasp hand grip  136  or second segment  126  of rider-operable lever  128  to urge it downward, thereby raising rear legs  10 ,  12  as well as the rear  50  of seat  16  to assist the rider to achieve a standing position. Rider-operable levers  128  may be provided on both sides of main frame  4  such that the rider may use both arms to raise seat  16  and to elevate rear legs  10 ,  12 . The skid-resistent pads  90  of foot  88  touchingly engage the floor surface  64  when second segments  126  of rider-operated levers  128  are urged downward, thereby stabilizing wheelchair  102  and resisting forward movement thereof. 
     FIGS. 8 and 9 depict another alternative embodiment wheelchair  202  provided with an attendant-operable lever  228  which may be operated from behind the wheelchair  202 . In this embodiment, wheelchair  202  is provided with elements identical to those of the wheelchair  2  of FIGS. 1-6 except the linkage members which elevate the rear of wheelchair  202  and the rear end  46  of seat frame  14  thereof are arranged such that rotation of attendant-operable lever  228  toward the rear of wheelchair  202  causes elevation. A transaxle  236  is journaled to the rear legs  10 ,  12  of wheelchair  202 . Attendant-operable lever  228  is fixed at its lower end  234  to transaxle  236  such that transaxle  236  axially rotates as attendant-operable lever  228  pivots rearwardly about its lower end  234 . Seatlift lever  156  and stake arm  154  extend from transaxle  236  and are fixed thereto, radiating outward in substantially opposing directions. As transaxle  236  rotates, seat lift lever  156  urges link  158  upward. Because link  158  is hingedly joined to the underside of seat frame  14 , the rear end  46  of seat frame  14  will rise. As seat lift lever  156  moves, stake arm  154  also rotates, urging stake  152  downward through guide bushing  166 . Guide bushing  166  is housed along cross piece  186  of guide frame  182  which is supported by its mounting to cross strut  180  which is fixed at its ends to rear legs  10  and  12 . Guide frame  182  guides stake  152  as it moves toward floor surface  64 . The lower end of stake  152  is provided with foot  188  which touchingly engages floor surface  64  when attendant-operable lever  228  is urged rearward, thereby raising rear wheels  72  above floor surface  64  while rear end  46  of seat frame  14  and hence seat  16  is elevated. 
     It is to be understood that many alternate mechanical linkages may be devised to cause the rear of frame  4  to be lifted while pivoting the front of seat  16  downward while also stabilizing the wheelchair upon floor surface  64 . For instance, FIG. 10 illustrates another alternative embodiment wheelchair  302  which operates to raise the rear  304  of the wheelchair  302  by rotating the rear wheels  306  forward and under the rear lets  308  of the wheelchair  302  when lever  310  is moved forward. 
     OPERATION 
     With a patient seated on seat  16  of wheelchair  2  with lever  28  in its relaxed, substantially upright position, the wheelchair  2  may be moved from place to place on its wheels  72 ,  74 . Once the patient&#39;s destination has been reached, an attendant may pull lever  28  toward the front of wheelchair  2  thereby elevating the rear of wheelchair  2  as well as rotating seat  16  such that front end  44  of seat frame  14  declines and rear end  46  thereof rises, to facilitate the movement of the patient from wheelchair  2  to a standing position. The attendant is thereby relieved of the need to reach substantially forward to grasp the patient&#39;s limbs or body to assist in bringing the patient to his or her feet and hence the risk of back strain to the attendant is substantially reduced.