Abstract:
A transportation apparatus includes a backrest and leg support pivotably connected to a seat portion. The seat portion is slidably connected to first and second spaced apart slide rails. Each slide rail includes a plurality of telescoping members. At least one middle leg and at least one rear leg depends downwardly from the seat portion. At least one middle wheel is connected to the middle leg and at least one rear wheel is connected to the rear leg. The middle wheel and rear wheel define a middle and rear rotation axes, respectively. At least one front wheel is operatively connected to the leg support. The middle leg is movable to adjust the vertical position of the middle wheel, and the rear leg is movable to adjust the vertical position of the rear wheel. The plurality of telescoping members slide the seat portion in a substantially horizontal direction in relation to the rear rotation axis or the middle rotation axis.

Description:
FIELD OF THE INVENTION 
   The invention relates to transportation devices for disabled people or other invalids. In particular, the invention relates to an apparatus which is adjustable from a chair position to a position which permits the apparatus to transport the invalid to a location or enclosure having a raised surface. 
   BACKGROUND OF THE INVENTION 
   The problems associated with transporting disabled people or other invalids are well known. Such persons are often unable to move sufficiently to get out of a wheelchair and lift themselves onto a raised surface such as a vehicle floor. Consequently, invalids must often be transported onto such raised surfaces. 
   As discussed above, one common example of a transportation obstacle is the transportation of an invalid from a ground surface into a vehicle. In order for an invalid to be transported into a vehicle in a conventional wheelchair, the vehicle may have to be specially modified. Such modification is costly and must be performed for each new vehicle purchased by the invalid. 
   A number of adjustable chairs for transporting an invalid onto a raised surface, such as a vehicle floor, are known. One such chair is disclosed in U.S. Pat. No. 4,105,242. However, this prior art chair requires the presence of a third party attendant to adjust the chair and to move it onto the raised surface. While adjusting the chair, the attendant is required to bear at least part of the weight of the invalid. 
   Accordingly, there is a need for an improved invalid transportation apparatus which is capable of transporting an invalid onto a raised surface while reducing the need for third party assistance. 
   SUMMARY OF THE INVENTION 
   According to a first aspect of the invention, a transportation apparatus for transporting an invalid onto a raised surface is provided. The transportation apparatus comprises a leg support pivotably connected to a seat portion. At least one middle leg and at least one rear leg depends downwardly from the seat portion. At least one middle wheel is connected to the middle leg and at least one rear wheel is connected to the rear leg. The middle wheel and rear wheel define a middle and rear rotation axes, respectively. At least one front wheel is operatively connected to the leg support. The middle leg is adapted to adjust the vertical position of the middle wheel, and the rear leg is adapted to adjust the vertical position of the rear wheel. The seat portion is adapted for movement in a substantially horizontal direction in relation to the rear rotation axis or the middle rotation axis. 
   According to a second aspect of the invention, a transportation apparatus for transporting an invalid onto a raised surface is provided. The transportation apparatus comprises a backrest and leg support pivotably connected to a seat portion. The seat portion is slidably connected to first and second spaced apart slide rails. Each slide rail comprises a plurality of telescoping members. At least one middle leg and at least one rear leg depends downwardly from the seat portion. At least one middle wheel is connected to the middle leg and at least one rear wheel is connected to the rear leg. The middle wheel and rear wheel define a middle and rear rotation axes, respectively. At least one front wheel is operatively connected to the leg support. The middle leg is adapted to adjust the vertical position of the middle wheel, and the rear leg is adapted to adjust the vertical position of the rear wheel. The plurality of telescoping members are adapted to slide the seat portion in a substantially horizontal direction in relation to the rear rotation axis or the middle rotation axis. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the accompanying drawings: 
       FIG. 1  is a top perspective view of an apparatus for transporting an invalid according to a preferred embodiment of the invention; 
       FIG. 2  is a bottom perspective view of the preferred embodiment; 
       FIG. 3  is a bottom perspective view of the preferred embodiment in the horizontal or stretcher position; 
       FIG. 4  is a partial cutaway perspective view of the preferred embodiment showing a rear leg and worm drive for the rear leg; 
       FIG. 5  is a partial perspective view of the preferred embodiment with the seat portion, backrest, and leg support removed; 
       FIG. 6  is a partial perspective view of the preferred embodiment showing a sliding rail; 
       FIGS. 7A-J  are a series of elevation views of the preferred embodiment illustrating entrance of the apparatus on a raised surface; and 
       FIGS. 8A-F  are a series of elevation views of the preferred embodiment illustrating exit of the apparatus from a raised surface. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIGS. 1 and 2  show an apparatus  10  for transporting an invalid according to an embodiment of the present invention. The apparatus includes a pivotable backrest  12  which is connected to a rear edge of a seat portion  14  by a hinge  16 . A leg support  18  is pivotably connected to a front edge of the seat portion  14 , as described in more detail below. Foldable arm rests  20   a ,  20   b  which connect to the backrest  12  and seat portion  14  may also be provided. 
   Referring to  FIGS. 1 and 3  (which shows the apparatus  10  in a horizontal or stretcher position), the seat portion  14  includes a frame  17 . Preferably, a pair of middle legs  30   a,b  and a pair of rear legs  32   a,b  depend downwardly from the frame. Middle wheels  34   a,b  are connected to lower ends of middle legs  30   a,b , respectively. Rear wheels  36   a,b  are connected to lower ends of rear legs  32   a,b , respectively. The middle wheels  34   a,b  define a rotation axis A, and the rear wheels  36   a,b  define a rotation axis B. Rotation axes A and B are shown in  FIG. 1 . Preferably, the rear wheels,  36   a,b  are conventional swiveling wheels. 
   Referring now to  FIG. 3 , a pair of front legs  38   a,b  are also preferably provided on the leg support  18 . Front wheels  40   a,b  are connected to lower ends of front legs  38   a,b . Preferably, front wheels  40   a,b  are able to roll only in a forward direction (i.e. the front wheels are prevented from rolling backward) by any suitable means, such as anti-reverse bearings (not shown). It will be understood by those skilled in the art that the apparatus  10  may be constructed without front legs  38   a,b . In an alternative embodiment, the front wheels  40   a,b  may be mounted directly to the underside of leg support  18 . 
   Continuing to refer to  FIG. 3 , leg worm drives  42   a - f  are provided to extend (i.e. lower) and retract (i.e. raise) middle legs  30   a,b , rear legs  32   a,b , and front legs  38   a,b , respectively. The leg worm drives  42   a - d  which move the middle legs  30   a,b  and rear legs  32   a,b  are mounted to the sides of the frame  17 . The leg worm drives  42   d,f  which drive the front legs are mounted to the underside of the leg support  18 . 
     FIG. 4  shows leg worm drive  42   c  and rear leg  32   a  in detail. Leg worm drive  42   c  includes a worm housing  50  which receives a threaded worm rod  52 . A conventional electric motor  54  which drives the worm rod  52  is mounted at one end of the worm housing  50 . An internally threaded worm follower  56  engages the worm rod  52 . The rotation of the worm rod  52  by electric motor  54  causes the worm follower  56  to move outwardly or inwardly along the worm rod  52  (depending on the direction of the rotation of the worm rod). Preferably, all of the leg worm drives  42   a - f  are substantially identical to leg worm drive  42   c . Consequently, the remaining leg worm drives are not illustrated in detail. 
   Continuing to refer to  FIG. 4 , rear leg  32   a  is suspended from worm drive  42   c . Rear leg  32   a  includes a primary member  60  which is hinged to the worm follower  56  at its upper end in any suitable fashion, such as by pin hinge  62 . At its bottom end, the primary member  60  is connected to rear wheel  36   a  (shown in  FIG. 3 ) also by pin hinge  62 . A secondary member  64  is hinged by pin hinge  62  to a proximate end  63  of the worm housing  50  at one end and to a point along the length of primary member  60  at the other end. A support member  66  is hinged to a lower end of the secondary member  64  and extends generally parallel with primary member  60 . The lower end of support member  66  is connected to rear wheel  36   a  (shown in  FIG. 3 ). The movement of the worm follower  56  toward the proximate end  63  of the worm drive  42   c  causes the hinged assembly of primary member  60  and secondary member  64  to extend downwardly away from the worm drive. The movement of the worm follower  56  toward the distal end  68  causes the hinged assembly of primary member  60  and secondary member  64  to retract upwardly toward the worm drive. The extension and retraction of the primary member  60  of the rear leg  32   a  in turn raises and lowers the rear wheel  36   a . The support member  66  acts to maintain the orientation of the rear wheel  36   a  in relation to the ground or floor surface. 
   Preferably, the rear leg  32   b  is identical to rear leg  32   a  and will not be further described. The remaining legs (middle legs  30   a,b  and front legs  38   a,b ) are preferably similar to rear leg  32   a , with the difference being that the remaining legs are constructed without support member  66 . It will be understood by those skilled in the art that the legs  30   a,b ,  32   a,b , and  38   a,b  may be constructed in any other suitable fashion which permits such legs to be extended and retracted. For example, the legs may be constructed from telescoping members. 
   Referring again to  FIG. 3 , electric motors  70   a,b  are mounted on the middle legs  30   a,b , respectively, in order to drive middle wheels  34   a,b . The electric motors driving the middle wheels  34   a,b  permit the apparatus  10  to be self-propelled. In other words, the invalid can operate the apparatus without assistance from an attendant. 
   Referring again to  FIG. 2 , a backrest tilting arm  80  is connected to a rear surface of the backrest  12 . The other end of the backrest tilting arm  80  is connected to a backrest worm drive  42   g . The backrest worm drive  42   g  is substantially identical to the leg worm drive  42   c  and will not be further described. The backrest tilting arm  80  preferably comprises a first member  82  (secured to backrest  12 ) hinged to a second member  84  by pin hinge  62 . The other end of the second member  84  is connected to the worm follower  56  (shown in  FIG. 4 ) of backrest worm drive  42   g  also by pin hinge  62 . Accordingly, backrest worm drive  42   g  moves the backrest tilting arm  80 , which in turn tilts the backrest  12 . 
   Referring again to  FIG. 3 , a leg support tilting arm  90  is provided to raise and lower the leg support  18 . One end of leg support tilting arm  90  is connected to the underside of leg support  18  by pin hinge  62 . The other end of leg support tilting arm  90  is connected to worm follower  56  (shown in  FIG. 4 ) of a leg support worm drive  42   h . The leg support worm drive  42   h  is substantially identical to the leg worm drive  42   c  and will not be further described. The leg support worm drive  42   h  moves the leg support tilting arm  90  to raise and lower the leg support  18 . 
   Referring to  FIG. 5 , the frame  17  preferably comprises two telescoping slide rails  100   a ,  100   b  running along opposing sides of the seat portion  14  (not shown in  FIG. 5  for clarity). A seat worm drive  42   i  is provided to slide the seat portion  14  on slide rails  100   a ,  100   b . The worm housing  50  of seat worm drive  42   i  is secured to slide rail  100   b  by bracket  102 . The worm follower  56  of seat worm drive  42   i  is secured to the underside the seat portion  14  by connector  104 . 
   Referring now to  FIG. 6 , each slide rail  100   a ,  100   b  preferably comprises three telescoping members to permit the seat portion  14  (shown in  FIG. 1 ) to translate by a distance of preferably at least 100% of its length. In particular, a middle  110  rail is received within a channel  111  of an outer rail  112 . An inner rail  114  slides within another channel  116  of the middle rail  110 . Bearings  118  may be provided to facilitate the sliding movement. The sliding rails  100   a ,  100   b  permit the seat worm drive  42   i  to slide the seat portion  14  forward and backward in relation to the rotation axis A, B of the middle wheels  34   a,b  and rear wheels  36   a,b . The seat worm drive  42   h  is substantially identical to the leg worm drive  42   c  and will not be further described. 
   A battery (not shown) and any suitable control system (not shown), such as a conventional electronic control system may be provided to operate electric motors  70   a ,  70   b  and the worm drives  42   a - i . The battery or batteries may be mounted under the seat portion  14  or behind the backrest  12 . The electronic control system may be linked to an actuator module (not shown) operated by the invalid. The actuator module may be mounted on the armrests  20 . The actuator module may include one or more joysticks or levers to control the various movements (described above) of the apparatus  10 . 
   It will be understood by those skilled in the art that use of the worm drives  42   a - i  is not essential. Any other suitable mechanism (such as hydraulics, servo motors, or the like) may be used to move the legs  30 ,  32 ,  38 , backrest  12 , leg support  18 , and seat portion  14 . 
   The operation of the preferred embodiment of the present invention will now be described with reference to  FIGS. 7A-J  and  8 A-F. The operation will be described in connection with the apparatus  10  entering and exiting a vehicle. However, it will be understood by those skilled in the art that the apparatus  10  may exit or enter any other raised surface (either enclosed or not) in the same manner. 
   The operation of the apparatus  10  in connection with entering the vehicle will be described first with reference to  FIGS. 7A-J . 
   The apparatus  10  is typically in the position shown in  FIG. 7A  for wheelchair operation. When the invalid wishes to transport herself onto a vehicle or other raised surface, the invalid first drives the apparatus  10  forward in proximity of the raised surface  150 . 
   Referring to  FIG. 7B , the invalid raises the leg support  18  into a substantially horizontal position and drives the apparatus forward until the middle wheels  34   a ,  34   b  are adjacent to the edge  152  of the raised surface  150 . 
   Referring to  FIG. 7C , front legs  38   a ,  38   b  then extend to lower front wheels  40   a,b  onto the raised surface  150 . If required due to height restrictions (such as a vehicle roof, the backrest  12  may be lowered (not shown in lowered position) to a height sufficient to clear vehicle roof or to a horizontal stretcher position at this stage. 
   Referring now to  FIG. 7D , the slide rails  100   a,b  extend to slide seat portion  14  forward relative to the rotational axis A (shown only in  FIG. 1 ) of middle wheels  34   a,b  until the center of gravity of the invalid is preferably located forward of the rotational axis A. The force of the mass of the invalid acting through the center of gravity is indicated on  FIG. 7D  by arrow CG. 
   Referring to  FIG. 7E , the middle wheels  34   a,b  are then raised to a height above the raised surface  150 . 
   Referring to  FIG. 7F , the slide rails  100   a,b  (not shown in  FIG. 7F ) retract causing the middle wheels  34   a,b  and rear wheels  36   a,b  to roll forward, such that middle wheels  34   a,b  are above the raised surface  150 . At the same time, the seat portion slides backward relative to rotational axis A (shown only in  FIG. 1 ). All of this occurs due to the fact that the front wheels  40   a,b  are prevented from rolling backwards by the anti-reverse bearings. 
   Referring to  FIG. 7G , middle legs  30   a,b  then lower the middle wheels  34   a,b  such that they are in contact with the raised surface  150 . 
   Referring to  FIG. 7H , the seat portion  14  again slides forward relative to the rotational axis A of middle wheels  34   a,b  such that the center of gravity CG of the invalid is forward of the rotational axis A. 
   Referring to  FIG. 7I , the rear legs  32   a,b  retract rear wheels  36   a,b  to a height above the raised surface. The apparatus  10  drives forward to a position where the rear wheels  36   a,b  are above the raised surface. 
   Referring to  FIG. 7J , the rear wheels  36   a,b  are then lowered until they are in contact with the raised surface. The slide rails  100   a,b  are retracted such that the middle wheels  34   a,b  and rear wheels  36   a,b  again roll forward on the raised surface. The seat portion  14  moves backward relative to rotation axis A to position the center of gravity CG of the invalid between the middle and rear wheels. In addition, depending on the height of the vehicle roof, the backrest  12  may be adjusted for comfort of the invalid. 
   The operation of the apparatus  10  in connection with exiting the vehicle will now be described with reference to  FIGS. 8A-F . 
   Referring to  FIG. 8A , the apparatus  10  is driven forward until the front wheels  40   a,b  overhang the edge  152  of the raised surface  150 . The front wheels  40   a,b  are then lowered until they are in contact with the ground surface  160 . 
   Referring to  FIG. 8B , the seat portion  14  then slides forward on slide rails  100   a,b  until the center of gravity CG of the invalid is forward of rotation axis A of middle wheels  34   a,b . This causes the front wheels  40   a,b  to move forward, further away from the edge  152  of the raised surface  150 . 
   Referring to  FIG. 8C , the slide rails  100   a,b  retract causing the middle wheels  34   a,b  and rear wheels  36   a,b  to roll forward due to the anti-reverse bearing on the front wheels  40   a,b . As a result, the middle wheels  34   a,b  overhang the edge  152  of the raised surface  150 . The center of gravity CG of the invalid is positioned between the rotation axes A and B (shown only in  FIG. 1 ) of the middle and rear wheels, respectively. 
   Referring to  FIG. 8D , the middle wheels  34   a,b  are then lowered until they are in contact with the ground surface  160 . The slide rails  100   a,b  again extend to slide the seat portion  14  forward such that the center of gravity CG of the invalid is forward of rotation axis A. 
   Referring to  FIG. 8E , the apparatus  10  then drives forward until the rear wheels  36   a,b  clear the edge  152  of the raised surface  150 . The rear wheels are lowered until they are in contact with the ground surface  160 . 
   Referring to  FIG. 8F , the slide rails  100   a,b  again retract causing the middle wheels  34   a,b  and rear wheels  36   a,b  to roll forward on the ground surface and causing the seat portion  14  to slide backward in relation to rotational axis A. 
   The front wheels  40   a,b  are then retracted and the leg support  18  is lowered to place the apparatus  10  in a wheelchair position shown in  FIG. 1 . 
   The present invention provides the advantage of permitting the invalid to transport herself in the apparatus  10  to and from raised surfaces of varying heights without the need of an attendant (either to push a wheelchair or to bear any weight of the invalid while moving the chair to or from a raised surface). 
   While the present invention as herein shown and described in detail is fully capable of attaining the above-described objects of the invention, it is to be understood that it is the presently preferred embodiment of the present invention and thus, is representative of the subject matter which is broadly contemplated by the present invention, that the scope of the present invention fully encompasses other embodiments which may become obvious to those skilled in the art, and that the scope of the present invention is accordingly to be limited by nothing other than the appended claims, in which reference to an element in the singular is not intended to mean “one and only one” unless explicitly so stated, but rather “one or more.” All structural and functional equivalents to the elements of the above-described preferred embodiment that are known or later come to be known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be encompassed by the present claims. Moreover, it is not necessary for a device or method to address each and every problem sought to be solved by the present invention, for it to be encompassed by the present claims.