Abstract:
A device and associated method transfer a person having a handicap from one location to another, such as into or out of a wheelchair, bed, or bathtub. A wheeled base provides mobility to the device. A post and lifter arm support the patient during the transfer. The post is connected to a stabilization arm, which temporarily connects using a stabilization interface to a stabilization bracket. The stabilization bracket is typically attached rather permanently to a wall, ceiling, or other structural feature that provides substantial stability to the system. In various embodiments, the lifter arm may be actuated by hydraulics, the stabilization arm may be extendable, and a pair of extra wheels on the mobility base are adjustable horizontally (e.g., along one hedge of the base frame) or vertically (down to decrease the load on the casters, or up to allow the lifter to be “crabbed” sideways in confined spaces).

Description:
REFERENCE TO RELATED APPLICATION 
       [0001]    This application is a non-provisional of U.S. Provisional Application No. 61/108,694, filed Oct. 27, 2008 with title “Patient Lifter with Variable Height, Variable Load Bearing, and Variable Horizontal Position Drive Wheels,” pending. 
     
    
     FIELD 
       [0002]    The present invention relates to land vehicles. More particularly, it relates to movable devices with patient transfer features. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0003]      FIG. 1  is a perspective view of a patient transfer device according to one embodiment of this disclosure. 
           [0004]      FIG. 2  is a perspective view of an indexed linkage means for use in the system of  FIG. 1 . 
           [0005]      FIG. 3  is a perspective view of a stabilization arm connection for use in the system of  FIG. 1 . 
           [0006]      FIG. 4  is a perspective view of a stabilization interface device for use in the system of  FIG. 1 . 
           [0007]      FIG. 5  is a perspective view of a stabilization bracket and interface device for use with the system of  FIG. 1 . 
           [0008]      FIG. 6  is a side view of an alternative stabilization mechanism for use with the system of  FIG. 1 . 
           [0009]      FIG. 7  is a perspective view of another portable patient lifting device according to the present description. 
           [0010]      FIG. 8  is a side view of a mobility base with center load-bearing wheels in a third embodiment according to the present description. 
           [0011]      FIG. 9  is a side view of the embodiment of  FIG. 8  with its center wheels raised. 
           [0012]      FIG. 10  is a side view of the embodiment of  FIG. 8  with its center wheels lowered. 
       
    
    
     DESCRIPTION 
       [0013]    For the purpose of promoting an understanding of the principles of the invention, reference will now be made to certain embodiments illustrated in the disclosure, and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended, such alterations and further modifications in the illustrated device, and such further applications of the principles of the invention as illustrated therein being contemplated as would normally occur to one skilled in the art to which the invention relates. 
         [0014]    Generally, this disclosure relates to a device and an associated method for transferring a person having a handicap from one location to another, such as transferring between a wheelchair and a bathtub, or between a wheelchair and a bed. One embodiment described herein includes five major components: a mobility base, a post and lifter arm, a stabilization arm, a stabilization interface, and a stabilization bracket. A perspective view of this embodiment is shown in  FIG. 1 . 
         [0015]    Mobility base  110  comprises a tubular frame with side members  112  and cross member  114 , with casters  116  attached to effect mobility of the lifter  100 . The casters  116  can all be locked, when required, for positional stability of the lifter  100 . Each caster  116  swivels when unlocked. The casters  116  lock and unlock simultaneously upon activation of a single lever, footpad, or other control mechanism (not shown). When casters  116  are locked, they can neither swivel about the caster stem bearings, nor roll about the caster axles. The base side pieces  112  and  114  can be moved so as to increase the width of the base to optimize lifter stability when desired, or to effect transfers from wider wheelchairs, lift chairs, or the like. 
         [0016]    Lifter post  120  is attached to a cross member  114  of the mobility base frame  110 . The lifter post  120  in this embodiment is removable from the base to allow for shipping, transporting in a vehicle, storage, and the like. The post can be attached at multiple locations along the cross member  114  of the base frame  110  in order to reduce the required length of the lifter arm  125  and stabilization arm  130 . Attached to the lifter post  120  is a lifter arm  125 . The lifter arm  125  is attached to the post  120  with an offset pivot point  127  (so it has a short end  128  and a long end  129 ) so it pivots up and down to allow a client to be lifted over the wall of a bathtub, off of a bed, etc. while hanging from the long end  129  of the lifter arm  125  in a sling (not shown). An actuator device  122  is attached to the short end  128  of the lifter arm  125  and to a position on lifter post  120  below pivot point  127 , to provide the mechanical push and pull required to pivot (raise or lower) the lifter arm  125  as required during use. The actuator device  122  and lifter arm  125  are attached to the post in such a way that they can pivot 360 degrees about the post  120  to perform side and rear transfers as required. Push handles  124  for maneuvering the lifter are also attached to the lifter post  120 . 
         [0017]    A stabilization arm  130  is attached to the lifter post  120  in a way that allows it to be rotated 360 degrees about indexed linkage means  132  at the top of the lifter post  120 , and is securely indexed at multiple angles to the post to effect transfers in multiple relative angular configurations. (See also  FIGS. 2-3 .) The stabilization arm  130  is designed to fold out of the way when not in use, or to be detached if the device is being used only as a traditional lifter. The stabilization arm is adjustable in length to effect transfers in multiple configurations and situations. The attachment point of stabilization arm  130  to the lifter post  120  can be varied in height to effect transfers in multiple configurations. 
         [0018]    A stabilization interface device  140  is attached to the end of the stabilization arm  130  opposite to the post attachment point. As illustrated in  FIG. 4 , the stabilization interface device  140  is attached pivotally to the stabilization arm  130  to allow stabilization of the lifter in multiple configurations. It contains a mechanism that assures a rigid, safe connection with the stabilization bracket  150  (see  FIG. 5 ). This attachment is robust, but is easily engaged and disengaged. In some embodiments, once the transfer is complete, the stabilization interface device  140  can be remotely detached from the stabilization bracket  150  so the lifter can be moved. This remote detachment is enabled in various embodiments by cables, pulleys, levers, motors, servos, and other mechanisms and techniques as will occur to those skilled in the relevant areas of technology in light of this disclosure. 
         [0019]    As shown in  FIG. 5 , a stabilization bracket  150  is securely attached to a wall in the vicinity of the transfer site. The stabilization interface device  140  on the end of the stabilization arm  130  securely latches to the wall-mounted stabilization bracket  150  to stabilize the lifter relative to the wall during transfers. In particular, spring-loaded pin  145  is urged into hole  155  when the three plates of stabilization interface device  140  are properly positioned around the three exposed sides of stabilization bracket  150 . This arrangement substantially prevents vertical movement of stabilization arm  130  when the mechanism is attached, but allows rotational movement about pin  135 , which permits placement in a variety of positions even where only a single stabilization bracket  150  is available. Multiple stabilization brackets  150  can be placed in different locations to enable stabilized transfers at each one, and several additional variations in configuration will be understood by those skilled in the relevant technology in view of this disclosure. 
         [0020]      FIG. 6  illustrates an alternative stabilization mechanism for use with the disclosed system. In this embodiment, stabilization arm  130  again rotates about pivot pin  135  to enable placement of post  120  in a variety of relative positions. In this attachment mechanism, however, stabilization interface device  240  has a wider opening than that of stabilization interface device  140 , and bracket  250  has matching angles between its outer faces. Further, stabilization interface device  240  has stabilization retainer  245 , which rests in slot  255  of stabilization bracket  250  when the device is securely in place. Stabilization retainer  245  in some embodiments is fixedly attached to the underside of the top panel of stabilization interface device  240 , while in others it is only temporarily secured in position but can rotate up and out of the way as the components are joined, or can be slid into channel  255  from the end of the channel. Alternative placements, forms, arrangements, and even attachment techniques will occur to those skilled in the art based on this disclosure. 
         [0021]    Another embodiment, illustrated in  FIG. 7 , is a portable patient lifting device  300  normally comprising a base  302  with two front and two rear swiveling casters  304  that provide mobility for the unit, a post  306  vertically attached to the base  302 , and a lifter arm  308  rotationally attached to the top of the post  306 . The design also has attached to the base  302 , between the front and rear casters  304 , at least two, but possibly more, adjustable load-bearing drive wheels  310  that do not swivel as casters do. These “load-bearing wheels”  310  are adjustable in height in relation to the bottom of the lifter base  302  and the four casters  304 , so the load-bearing wheels  310  can, when desired, be adjusted to be lower in height than the base  302  and casters  304 , essentially allowing them to bear more of the load of the lifter system  300  than the four swiveling casters  304  do. When the load-bearing wheels  310  are in this position, this adjustment essentially decreases the load on the axles and swivel bearings of the four casters  304 , thereby decreasing the effort required for a person to push or pull the lifter system  300 . 
         [0022]    An added benefit of the lowered position of the load-bearing wheels  310  is that the lifter  300  is easier for a caregiver to maneuver because it tracks in a more straight line over distances, and turns more easily in confined spaces, such as in situations where a sharp 90-degree turn maneuver is required to go from a hallway through a door, etc. The load-bearing wheels  310  can be raised to allow the lifter  300  to be maneuvered freely in all directions, unlimited by the friction of the load-bearing wheels  310  against the surface, and to allow the four casters  302  to provide maximum stability during transfer of a patient. The adjustment in height of the load-bearing wheels  310  can be accomplished in many ways that will occur to those skilled in the art based on the present disclosure. In one example, the adjustment is accomplished by a rotating cam attached to a lever or some other mechanical device that reliably and easily accomplishes the vertical adjustment of the load-bearing wheels. In other examples, the adjustment is achieved by powered and/or hydraulic-assisted mechanisms. 
         [0023]    In some variations of this embodiment, the horizontal position of the load-bearing wheels  310  along the frame of the base  302  can also be adjusted, as illustrated by the non-vertical arrows near wheels  310  in  FIG. 7 . The adjustment is normally from front-to-back between the four casters  302 , allowing the load-bearing wheels  310  to be placed, as necessary or preferred, directly below the center of mass of the lifter. This adjustability allows users to optimize the stability, maneuverability, and versatility of the lifter  300 . 
         [0024]    One variation of the placement, operation, and movement of load-bearing wheels  310  is shown in  FIGS. 8-10 . The front and rear ACME screw posts  406   a  and  406   b  are rigidly connected to the top surface of the lifter base. The ACME screw  401  is held in vertical and horizontal alignment by the front and rear ACME screw posts  406   a  and  406   b , and the four shaft collars  404 . The ACME screw  401  is allowed to rotate freely through holes drilled in the front and rear screw posts  406   a  and  406   b . The shaft collars  404  prevent the ACME screw from moving horizontally in relation to the ACME screw posts  406   a  and  406   b . As the ACME screw  401  is rotated with the ACME screw crank handle  405 , the ACME screw nut  402  and the wedge  403 , which are rigidly connected to each other, move back and forth along the lifter base  409 . The center load bearing wheel assembly  407  is attached to the underside of the lifter base  409  by a pivot point  408 . 
         [0025]    The ACME screw nut  402  and wedge  403  are positioned in relation to the load bearing wheel pivot point  408  so that, as the ACME screw nut  402  and wedge  403  are moved back and forth by rotation of the ACME screw  401 , the center load bearing wheel assembly  407  moves up (see  FIG. 9 ) and down (see  FIG. 10 ) in relation to the front and rear casters  411 . This wedging action effectively offloads the front and rear casters  411 , allowing the lifter to be pushed, pulled, and maneuvered much more easily. 
         [0026]    In other variations on the lifter of  FIG. 1 , only two of the wheels are castors, while two others (such as the “rear” wheels on the corners nearest the post) are wheels that are held in fixed orientation relative to the lifter base. This configuration provides somewhat better straight-line tracking than the four-castor version. 
         [0027]    While the inventions have been illustrated and described in detail in the drawings and foregoing description, the same is to be considered as illustrative and not restrictive in character, it being understood that the preferred embodiment has been shown and described and that changes and modifications that come within the spirit of the invention are desired to be protected.