Wheelchair lift

Abstract

A vehicle-mounted device for use in moving a wheelchair and its occupant to and from the bed of a vehicle, comprising a platform for supporting the wheelchair, two parallelogram linkages having base links secured in place in the vehicle and end links carried by elongated arms swinging in space vertical planes, .[.and means securing the platform.]. .Iadd.the platform being secured .Iaddend.to the end links for movement in a generally horizontal attitude along an arcuate path so that one edge of the platform passes close to the edge of the bed of the vehicle at the access opening, and engages a stop in the vehicle for folding the platform into a storage position as the linkages complete their arcs. A motorized chain-and-sprocket drive swings the linkages between lowered, outwardly extending positions and raised, upright storage positions in the vehicle, and controls are provided for operating the drive and stopping the platform in an intermediate, entry position level with the bed. A first embodiment has the base and end links horizontal, the platform carried on upright posts, and a second embodiment has the end and base links upright.

I claim: 
     
       1. A wheelchair lift mountable in a vehicle adjacent an access opening thereof, for use in moving a wheelchair and its occupant to and from a generally horizontal bed of the vehicle, comprising: a pair of spaced parallelogram linkages each having a base link mountable in said vehicle adjacent the access opening, two side-by-side elongated arms pivotally mounted on said base link for swinging about spaced, parallel axes between upright positions in the vehicle, in which the arms extend upwardly from said base links, and lowered positions in which said arms project out of the vehicle through the access opening, and an end link parallel to said base link and pivotally mounted on the ends of said arms opposite the base link;   said linkages being spaced apart for mounting in the vehicle adjacent opposite sides of the access opening for swinging in substantially parallel planes, and to leave a passageway for a wheelchair between the linkages;   a flat and generally rectangular platform sized to support a wheelchair, said platform having one edge disposed beneath the said end links when said arms are in said lowered positions;   posts extending from said end links down to said platform;   a pivot connecting each of said posts to said platform for tilting of the platform about an axis above, and extending along, said one edge;   first stop means carried by said posts and acting against said platform to hold the platform against downward tilting from a generally horizontal operating position, but permitting upward tilting of the platform;   said posts being of a preselected length for supporting said platform at ground level when said arms are in the extended position, and for moving said one edge along an arc passing closely adjacent the edge of the bed at the access opening, and past the edge through the opening;   drive means for selectively swinging the arms of said linkages from said lowered positions to said upright positions and back;   control means for actuating said drive means and for stopping said linkages in each direction of movement with said platform in an intermediate position level with the bed, for movement of a wheelchair into and out of the vehicle;   and cam means positioned along said arc adjacent said base links for engagement with said one edge after the latter passes through the access opening and as the arms of said linkages swing into said upright positions, and operable to force said one edge downward to tilt said platform upward into a storage position.   
     
     
       2. A wheelchair lift as defined in claim 1 in which said drive means includes a reversible motor, and a chain-and-sprocket drive including at least one length of chain having one end connected to one of said linkages adjacent the end link thereof, and a sprocket for said chain supported inside the vehicle and driven by said motor, said chain extending from said end link to said sprocket and being engaged with the latter to be fed longitudinally in opposite directions by said sprocket, thereby to swing said linkages between said positions. 
     
     
       3. A wheelchair lift as defined in claim 2 further including a resiliently extendable spring connecting said chain to said linkage. 
     
     
       4. A wheelchair lift as defined in claim 2 further including two support posts extending upwardly from said base links, said drive means including sprockets rotatably mounted on the upper end portions of said posts, a chain on each of said sprockets having a first end portion hanging downward and a second end portion extending from the sprocket to the associated end link, and connected to the latter, and a motor for driving said sprockets to feed said chains longitudinally in unison, thereby to swing said linkages. 
     
     
       5. A wheelchair lift as defined in claim 1 in which said arms are straight bars, and are disposed in vertically spaced relation in a common plane. 
     
     
       6. A lift mountable in a vehicle adjacent an access opening thereof, for use in moving an object such as a wheelchair to and from a generally horizontal bed of the vehicle, comprising: a pair of parallelogram linkages each having a base link mountable in the vehicle adjacent the access opening, two side-by-side elongated arms pivotally mounted on said base link for swinging about spaced, parallel axes between upright positions in the vehicle and outwardly extending, lowered positions, and an end link pivotally mounted on the ends of said arms opposite said base link;   said linkages being spaced apart for mounting in the vehicle for swinging in substantially parallel planes;   a platform for holding the object;   means connecting one edge portion of said platform to both of said end links and holding the platform in a preselected angular position on said end links to maintain the platform generally parallel to said bed during swinging of said linkages and to move said one edge along an arc passing close to the end of the bed at the access opening;   and drive means for selectively swinging said linkages to said upright position, said lowered position, and an intermediate position in which said platform is level with the bed with said one edge adjacent the end thereof, including a reversible electric motor and operating circuitry therefor, first and second manual actuating switches for operating said motor from outside the vehicle and from inside the vehicle, a third manual switch mounted adjacent said platform for movement therewith and for operation by a person on the platform, and switch means responsive to movement of said platform to said intermediate position from either direction for overriding said third switch and stopping the platform in said intermediate position.   
     
     
       7. A lift as defined in claim 6 in which said connecting means connect said platform to said end links for upward pivotal movement from said preselected angular position about an axis extending along, and spaced above, said one edge, for folding of said platform upwardly into a storage position when said arms are in the upright positions, while preventing downward pivoting of the platform from said preselected angular position, and further including cam means in said vehicle and follower means adjacent said one edge, for forcing said one edge downwardly as said arms approach said upright position, thereby to fold the platform automatically to said storage position. 
     
     
       8. A lift mountable in a vehicle adjacent an access opening thereof, for use in moving an object such as a wheelchair to and from a generally horizontal bed of the vehicle, comprising: a pair of parallelogram linkages each having a base link mountable in the vehicle adjacent the access opening, two side-by-side elongated arms pivotally mounted on said base link for swinging about spaced, parallel axes between upright positions in the vehicle and outwardly extending, lowered positions, and an end link pivotally mounted on the ends of said arms opposite said base link;   said linkages being spaced apart for mounting in the vehicle for swinging in substantially parallel planes;   a platform for holding the object;   two posts extending from said end links down to said platform;   a pivot connecting the lower end portion of each post to said platform adjacent a front corner thereof, for tilting of the platform about an axis disposed above, and extending along, a front edge of the platform, and holding said platform for movement of said front edge along an arc passing close to the end of the bed at the access opening, and beyond the end of the bed, into the vehicle;   means for preventing downward tilting of said platform from a generally horizontal position, but permitting upward tilting into a storage position in which the rear edge of the platform is adjacent said posts;   drive means for selectively swinging the linkages, in unison, to said upright position, said lowered position, and an intermediate position in which said platform is level with the bed with said front edge adjacent, but spaced from, the end thereof;   means on said platform and said linkages for tilting said platform to said storage position automatically as an incident to movement of said linkages to said upright positions, comprising at least one set of cam and follower elements including a follower on said platform adjacent said front edge, and a cam on one of said base links inside the vehicle positioned to engage said follower and cam the latter downwardly as said linkages move into said upright positions.   
     
     
       9. A lift mountable in a vehicle adjacent an access opening thereof, for use in moving an object such as a wheelchair to and from a generally horizontal bed of the vehicle, comprising: a pair of parallelogram linkages each having a base link mountable in the vehicle adjacent the access opening, two side-by-side elongated arms pivotally mounted on said base link for swinging about spaced, parallel axes between upright positions in the vehicle and outwardly extending, lowered positions, and an end link pivotally mounted on the ends of said arms opposite said base link;   said linkages being spaced apart for mounting in the vehicle for swinging in substantially parallel planes;   a platform for holding the object;   two posts extending from said end links down to said platform;   a pivot connecting the lower end portion of each post to said platform adjacent a front corner thereof, for tilting of the platform about an axis disposed above, and extending along, a front edge of the platform, and holding said platform for movement of said front edge along an arc passing close to the end of the bed at the access opening, and beyond the end of the bed, into the vehicle;   means for preventing downward tilting of said platform from a generally horizontal position, but permitting upward tilting into a storage position in which the rear edge of the platform is adjacent said posts;   drive means for selectively swinging the linkages, in unison, to said upright position, said lowered positions; and an intermediate position in which said platform is level with the bed with said front edge adjacent, but spaced from, the end thereof, said drive means including two sprockets rotatably supported in the vehicle adjacent said access opening above the bed thereof, a chain for each of said sprockets having one end portion extending from the sprocket outwardly over one of the linkages, means connecting said chains to said linkages, means for driving said sprockets to feed said chains back and forth and swing said linkages between said positions;   means for tilting said platform to said storage position automatically as said linkages move to said upright positions and including means stopping inward movement of said platform as said linkages move to said upright positions, and means, including said chains, operating to tilt the platform to said storage position after inward movement of said platform is stopped. .Iadd. 10. In a wheelchair lift device mounted in an opening of a vehicle for selectively moving a wheelchair to the bed of the vehicle from the ground adjacent the vehicle and to the ground from the bed of the vehicle, the combination comprising   two base structures rigidly mounted to the vehicle, one of each of said structures located adjacent opposite sides of the opening of the vehicle so as to not interfere with entry or egress through said opening,   two straight members, each pivotally mounted at one of its ends to spaced points on each of said base structures for arcuate parallel movement about the pivotal mounts between an upright position in the vehicle to an outwardly extending lowered position,   two straight end link members, each pivotally attached to the ends of one pair of said straight members at their ends opposite said base structures,   a movable horizontally arranged platform for receiving the wheelchair and occupant,   means connecting one edge portion of said platform to both of said end link members and for holding the platform in a substantially horizontal plane during the arcuate parallel movement of the two pairs of straight members,   drive means comprising a reversible electrical motor for selectively moving said straight members through said arcuate parallel movement,   means for selectively causing said platform to rotate about one edge to a tilted, stored position within said vehicle when said pairs of straight members are in their upright position in the vehicle, and,   electrical switches selectively operable to determine the extent and direction of movement of said straight members and said platform and the   
     
     
        direction of rotation of said motor. .Iaddend..Iadd. 11.  The wheelchair lift device of claim 10, wherein the platform is pivotally connected to said end link members. .Iaddend. .Iadd. 12. A lift mountable in a vehicle adjacent an access opening thereof, for use in moving an object such as a wheelchair to and from a generally horizontal bed of the vehicle, comprising: a pair of parallelogram linkages each having a base link mountable in the vehicle adjacent the access opening, two elongated arms pivotally mounted on said base link for swinging about spaced, parallel axes between upright positions in the vehicle and outwardly extending, lowered positions, and an end link pivotally mounted on the ends of said arms opposite said base link;   said linkages being spaced apart for mounting in the vehicle for swinging in substantially parallel planes;   a platform for holding the object;   means pivotally connecting one edge portion of said platform to both of said end links for moving said one edge along an arc passing close to the end of the bed at the access opening;   drive means for selectively swinging the arms of said linkages from said lowered positions to said upright positions and back and further coupled for tilting the platform into a vertical storage position about an axis generally along the one edge of the platform after the elongated arms of said linkages have reached the upright position;   control means for actuating said drive means and for stopping said linkages in each direction of movement with said platform in an intermediate position level with the bed, for movement of a wheelchair into and out of the vehicle; and   means for preventing downward tilting of said platform from a preselected angular position, but permitting upward tilting into the storage position. .Iaddend.