Self-leveling hoist for wheel chairs

Abstract

A hoist having a mobile frame, a pair of supports mounted on the frame, an arm mounted for pivotal movement on each support, a platform secured on the remote ends of the arms, a ram interconnecting each support and its respective arm for elevational movement in parallelism, and a power system mounted in driving relation to the rams.

Description

BACKGROUND OF THE INVENTION

The present invention relates to a self-contained hoist and more particularly to such a hoist which is capable of being operated and maintained by a disabled person for purposes of gaining access to elevated areas.

Lifting devices are employed in a multitude of areas of application. Such devices commonly require permanent implacement at a specific location and are dependent upon external sources of power for their operation. This is particularly onerous for disabled persons such as paraplegics and paralytics borne by wheel chairs who must use such lifting devices to gain entrance to elevated areas which are otherwise inaccessible. Disabled persons normally depend upon others to mount the device in position for use and frequently must rely upon others to operate and maintain the device. This dependence and the attendant embarrassment discourages the use of such devices.

Furthermore, the dependence upon external sources of power severely limits the locations at which such devices may be employed. Thus, gaining entrance to automobiles, buses, trains, aircraft, mobile homes, buildings and the like becomes difficult to the point of practical impossibility. Because of these deficiencies, disabled persons are dissuaded from exposing themselves to situations in which such dependence upon a lifting device as well as other persons would be required.

Therefore, it has long been recognized that it would be desirable to have a hoist which can be operated and maintained by disabled persons without dependence upon others thereby encouraging the mobility and self-reliance of such persons.

SUMMARY OF THE INVENTION

In view of the foregoing, it is an object of the present invention to provide an improved self-contained hoist.

Another object is to provide such a hoist which does not require permanent or semipermanent implacement prior to use.

Another object is to provide such a hoist which may easily be motivated to any suitable location for use.

Another object is to provide such a hoist which is adapted to be operated solely by a disabled person to elevate himself.

Another object is to provide such a hoist which can be maintained by disabled persons.

Another object is to provide such a hoist which is not dependent upon external sources of energy for its operation.

A further object is to provide such a hoist which is balanced so as to remain stable during operation.

Further objects and advantages are to provide improved elements and arrangements thereof in a device for the purposes described which is dependable, economical, durable and fully effective in accomplishing its intended purposes.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of the self-contained hoist of the present invention.

FIG. 2 is a top plan view of the hoist.

FIG. 3 is a side elevation of the hoist.

FIG. 4 is an end view of the hoist.

FIG. 5 is a somewhat enlarged fragmentary vertical section taken on line 5--5 in FIG. 2.

FIG. 6 is a fragmentary top plan view of the portion of the hoist viewed in FIG. 5.

FIG. 7 is a schematic illustration of the power system for the hoist.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring more particularly to the drawings, the selfcontained hoist of the present invention is generally indicated by the numeral 10. As shown in FIG. 1, the hoist is adapted to support a wheel chair 11 shown in dashed lines in FIG. 1. The hoist is adapted to be positioned in rested relation on a floor or ground surface generally indicated by numeral 12 in FIGS. 3 and 4. As shown in FIG. 3, the hoist is positioned in its normal operational environment adjacent to a floor 13 shown in dashed lines.

The hoist 10 has a substantially rectangular frame 20 composed of a pair of spaced, substantially parallel angle-iron bars 21 having opposite ends 22. The bars are interconnected at their corresponding opposite ends by a pair of substantially flat cross plates 23. A pair of support members 24, having remote ends 25 are individually secured, as by welding, adjacent to corresponding opposite ends of the angle iron bars in substantial right angular relation. A ground wheel assembly 26 is secured, as by welding, on each support member immediately adjacent to the opposite end of its respective angle-iron bar, as best shown in FIG. 3.

A bracket or mounting assembly 35 is slidably mounted on each of the support members 24. Each of the mounting assemblies has a tubular sleeve 36, having a front side 37 and a back side 38, slidably received on its respective support member. The back side of each sleeve has a pair of screw threaded bores 39. A bolt 40 is screw threadably received in each of the bores and adapted to be tightened into binding engagement with its respective support member so as to secure the sleeve in position. A pivotal connection 41 is fastened on the back side of each tubular sleeve, as best shown in FIGS. 5 and 6. A cross member 42 is affixed on the sleeves in interconnecting relation substantially normal to the support members.

Each of the mounting assemblies 35 has a mount 46 secured for pivotal movement on its respective pivotal connection 41. Each of the mounts has a pair of substantially flat side plates 47 interconnected by a stop plate 48 extending substantially normal to and between the side plates. Each of the side plates has an integral pivot arm 49 extending from its respective support member to the left, as viewed in FIG. 3, and an oppositely extending ram arm 50. The pivot arms of each mount are secured for pivotal movement on the pivotal connection of their respective tubular sleeve 36. A screw threaded bore 51 is extended through the stop plate of each mount and has an adjustment bolt 52 screw threadably received therein for engagement with the front side 37 of the tubular sleeve.

As best shown in FIGS. 5 and 6, each of the mounts 46 has an upper pivotal connection 60 extending between the side plates 47 thereof substantially right angularly thereto. A lower pivotal connection 61 extends between the side plates in spaced relation to the upper pivotal connection. A ram connection 62 extends between the ram arms 50 of the side plates of each mount. A normally closed limit switch 63 is adjustably mounted on the ram connection of one of the mounts. The switch has a switch lever 64 operably mounted thereon.

A pair of adjustable braces 70 are extended between the frame 20 and each of the mounting assemblies 35. Each brace has a rigid tube 71 pivotally secured outwardly on each of the angleiron bars 21 intermediate the opposite ends 22 thereof, as best shown in FIGS. 1, 3, and 4. Each of the tubes has an adjustment nut 72 rotationally mounted at the end thereof remote from the frame. A screw-threaded eye bolt 73 is pivotally mounted on each of the pivotal connections 41 outwardly of its respective mount 46 and adjustably screw-threadably received in the adjustment nut of its respective tube, as best shown in FIG. 6.

An arm assembly 80 is mounted on each of the mounting assemblies 35 in alignment with its adjacent angle-iron bar 21. Each of the arm assemblies has a lower arm member 81, having opposite ends 82, pivotally fastened adjacent to one of its opposite ends on the lower pivotal connection 61. Each arm assembly has a pair of upper arm members 83, having opposite ends 84, individually pivotally mounted on the upper pivotal connection 60 of each mounting assembly. A ram 85, having an extendible power arm 86, is pivotally mounted on the ram connection 62 of each mount 46. A pivotal connection 87 is affixed on each of the lower arm members adjacent to the opposite end thereof remote from its respective mounting assembly. The power arm of each ram is connected to the pivotal connection 87 of its respective arm assembly, as best shown in FIG. 3.

A platform 94 is mounted on the remote ends of the arm assemblies 80. The platform has opposite sides 95 and has a pair of spaced, substantially parallel inverted channel members 96. Four substantially parallel cross plates 97 are secured on the channel members extending substantially right angularly thereto. A floor 98 is fastened, as by welding, on the channel members and cross plates in supported relation. The floor has a pair of wheel depressions 99 integrally formed therein, as best shown in FIG. 2. A pair of upstanding side rails 100 are mounted on the floor in spaced relation in substantial alignment with their respective adjacent channel members. A conduit 101 is fastened on each of the side rails extending to the floor substantially normal thereto.

A return bent mount 109 is secured, as by welding, on the cross plates 97 adjacent to each of the channel members 96 midway between the opposite ends thereof. Each mount has an upper pivotal connection 110 and a lower pivotal connection 111 disposed substantially right angularly to their respective channel members. The pivotal connections 110 and 111 of each mount are axially aligned with their corresponding respective pivotal connections of the other mount. The ends 82 of the lower arm members 81 remote from the arm mounting assemblies 35 are pivotally connected to their respective lower pivotal connections 111. Similarly, the remote opposite ends 84 of the pair of upper arm members 83 are pivotally connected to their respective upper pivotal connections 110. The upper arm members and lower arm member of each arm assembly thereby form a parallelogram type linkage so as to support the platform 94 for movement in parallelism on the frame 20, as best shown in FIG. 3. An elongated box-like container 112 is mounted, as by welding, on the cross member 42 between the mounting assemblies 35. The container has an internal receptacle 113 and affords a cover 114 which is removable from the container to gain access to the receptacle.

As shown in dashed lines in FIG. 2, the receptacle of the container has a power source generally indicated by numeral 119 mounted therein. The power source includes a fluid circulating system generally indicated by the numeral 120, as schematically illustrated in FIG. 7. The system is preferably hydraulic so as to insure a smoothness of operation. The system includes a fluid reservoir 121 which is mounted within the receptacle 113 of the container 112, as shown in FIG. 2. The fluid reservoir contains a conventional hydraulic fluid. The system further includes a fluid pump 122, a return valve 123 and a regulator valve 124 all of which are similarly mounted in the receptacle of the container, as shown in dashed lines in FIG. 2. A pump conduit 125 interconnects the reservoir and the pump in fluid transferring relation. A supply conduit 126 is extended from the fluid pump in fluid transferring relation. A pair of flexible ram hoses 127 are extended from the remote end of the supply conduit and are individually connected in fluid transferring relation to the rams 85 adjacent to their respective power arms 86 in the conventional manner. A return conduit 128 is connected to the supply conduit in fluid transferring relation and is operably extended through the return valve 123, the regulator valve 124 and connected to the fluid reservoir 121.

The power source 119 further includes an electrical drive system schematically illustrated in FIG. 7 and generally indicated by the numeral 135. The electrical system has a pump motor 136 mounted in driving relation to the pump 122. The electrical system further includes a battery 137, and a charger 138 having an electrical connection 139 adapted for insertion in a conventional wall socket, not shown. The battery and charger are mounted in the receptacle 133 of the container 112. A solenoid 140 is mounted in operable connection with the return valve 123 and adapted to maintain the valve in a closed configuration when the solenoid is not energized. A platform control mechanism or switch box 141 is mounted on the side rail 100 on the left as viewed in FIG. 4. The box operably mounts a spring loaded, normally open platform lifting switch 142 and a similarly spring loaded, normally open platform lowering switch 143.

The electrical system 135 has an electrical circuit 151. The circuit includes a first motor conductor 152 electrically interconnecting the battery 137 and the motor 136. A second motor conductor 153 extends from the motor and is in turn connected to the limit switch 63. A lifting switch conductor 154 interconnects the limit switch and the lifting switch 142. A return conductor 155 interconnects the lifting switch and the battery.

The electrical circuit 151 further includes a lowering switch conductor 160 which interconnects the first motor conductor 152 and the lowering switch 143. A first solenoid conductor 161 interconnects the lowering switch and the solenoid 140. A second solenoid conductor 162 interconnects the solenoid and the return conductor 155. A first charger conductor 163 interconnects the charger 138 and the return conductor 155. A second charger conductor 164 is extended from the charger to a normally open control switch 165. A third charger conductor 166 operably interconnects the control switch and the first motor conductor 151. Conductors 154, 155, 160 and 161 extend through the conduit 101 of the side rail 100 mounting the control box 141 for connection to their respective lifting switch 141 and lowering switch 143, as best shown in FIG. 5.

OPERATION

The operation of the described embodiment of the subject invention is believed to be clearly apparent and is briefly summarized at this point. The hoist 10 can be transported along the ground surface 12 on its wheel assemblies 26 to the desired location for use by grasping the cross plate 23 farthest from the support members 24 so as to tilt the hoist back on the wheel assemblies. This can frequently be accomplished even by a disabled person in a wheel chair 11 due to the optimum distribution of weight relative to the wheel assemblies by the mounting of the platform 94 and container 112 on opposite sides of the support members 24. The hoist is normally positioned with the container 112 disposed beneath the floor 13 to which access is sought, as shown in FIG. 3. With the frame 20 in rested engagement with the ground surface, the hoist is in quite stable attitude for the performance of a variety of lifting operations.

Normally adjustment of the elevation of the mounting assemblies 35 on the support members 24 is not required due to the capability of selectively positioning the platform 94, as will subsequently be described. However, where such adjustment is desired, the bolts 40 of each tubular sleeve 36 are first loosened. The adjustment nut 72 of each adjustable brace 70 is then adjusted so as to extend or retract the eye bolt 73. The mounts 46 are accordingly adjusted on their respective support members 24 as desired. When the desired position has been selected, the bolts 40 are again tightened in their respective screw threaded bores 39, and against the support member securely to retain their respective mount 46 in the selected position. The limit switch 63 is then adjusted on its respective ram connection relative to the adjacent upper arm member 83 to define a maximum elevation for the platform, as will subsequently become more clearly apparent.

The hoist 10 is then operated to motivate the platform 94 to a lowered position in engagement with the frame 20. A disabled person desiring to use the hoist rolls the wheel chair 11 on which he is seated onto the platform and positions the chair so that it is securely received in the wheel depressions 99 of the floor 98. The wheel chair is preferably oriented so that the person is facing in the direction of the container 112. The lifting switch 142 is subsequently pressed against spring tension and retained in this position for as long as upward movement of the platform is desired. As shown schematically in FIG. 7, closing of the lifting switch completes the electrical circuit 151 from the battery 137, through the first motor conductor 152 to the motor 136, from the motor through the second motor conductor 153 to the limit switch 63, from the limit switch through the lifting switch conductor 154 to the lifting switch, and subsequently through the return conductor 155 to the battery.

Thus, electrical energy is supplied to the motor 136 which in turn operates the pump 122. Accordingly, fluid, preferably hydraulic, is pumped from the fluid reservoir 121 through the pump conduit 125, the supply conduit 126, the ram hoses 127 and subsequently into the rams 85. As a result the power arms 86 of the rams are gradually and smoothly retracted. This contraction, as can best be seen in FIG. 3, causes the lower arm member 81 of each arm assembly 80 to be upwardly pivoted about the lower pivotal connection 61 thereof. The parallelogram type linkage of the upper arm members 83 and lower arm members 81 insures that the platform 94 is, as a result, elevated under hydraulic power with the platform disposed parallel to the frame, or, in other words, horizontally.

When the arm assemblies 80 reach the preselected elevated position, the switch lever 64 of the limit switch 63 is contacted by its adjacent upper arm member 83 so as to trip the limit switch and open the electrical circuit 151. This terminates the flow of electricala energy through the motor 136 so as to stop the introduction of hydraulic fluid to the rams. Thus, the platform's upward movement is discontinued. The platform 94 is retained in the elevated position since fluid cannot return to the reservoir through the supply conduit 126 or return conduit 128. The operator can alternatively, of course, stop upward movement before the limit switch 63 is tripped by simply releasing the lifting switch 142 and allowing spring tension to again open the electrical circuit at that point. However, normally the hoist is adjusted so that the upper arm member trips the switch lever 64 at the time the floor 13 is reached by the platform.

After the switch lever 64 is tripped, the operator releases the lifting switch 142 to allow the electrical circuit 151 again to be broken. Subsequently the operator simply motivates the wheel chair 11 off the floor 98 of the platform 94 and onto the floor 13. As long as the return valve 123 remains closed, the rams 85 remain in their contracted configuration so as to maintain the platform at the selected elevated level.

To transfer from the floor 13 to the ground surface 12, the operator simply rolls the wheel chair 11 onto the platform 94. Subsequently the lowering switch 143 is pressed against spring tension to complete a portion of the electrical circuit 151. The portion of the circuit completed extends from the battery 137 through the first motor conductor 152, through the lowering switch conductor 160 to the lowering switch, through the first solenoid conductor 161 to the solenoid 140, through the second solenoid conductor 162 to the return conductor 155 and back to the battery. Thus the solenoid is energized to open the return valve 123 thereby allowing hydraulic fluid to be discharged under pressure through the ram hoses 127, the supply conduit 126, and the return conduit 128 to the reservoir 121. The regulator valve 124 insures that the flow of hydraulic fluid is maintained at a constant, relatively slow rate of speed so that the platform is lowered slowly and evenly.

When the platform reaches the desired lowered position, the lowering switch 143 is released to again allow spring tension to open the portion of the electrical circuit 151 through the solenoid 140. As a result, the return valve 123 again closes to terminate the flow of fluid back to the reservoir 121 and retain the platform 94 in the desired position. The operator then simply rolls the wheel chair 11 from the platform as desired.

It will be noted that the hoist 10 of the present invention is entirely self-contained not being dependent upon any outside source of energy. The charger 138, with its associated electrical connection 139, is adapted to permit charging of the battery 137 when convenient by insertion of the electrical connection into a conventional electrical wall outlet, not shown. When the control switch 165 is manually closed, electrical energy is allowed to flow through the connection to the charger which, in the conventional manner produces the proper electrical voltage required for charging the battery. This energy is transmitted through the battery by the charger conductors 163, 164 and 166. Disabled persons can readily perform such a charging operation as well as otherwise maintaining the hoist. Thus, the container 112 is at a convenient heighth for servicing the battery and other elements contained therein from a wheel chair.

Therefore, the hoist of the present invention is entirely self-contained not being dependent upon any outside source of energy nor requiring permanent or semipermanent installation prior to use. Furthermore, the hoist is adapted readily to be adjusted, operated and maintained even by disabled persons without dependence on other persons thereby encouraging mobility and self-reliance.

Although the invention has been herein shown and described in what is conceived to be the most practical and preferred embodiment, it is recognized that departures may be made therefrom within the scope of the invention, which is not to be limited to the illustrative details disclosed.

Claims

Having described our invention, what we claim as new and desire to secure by Letters Patent is;

1. A wheel chair hoist comprising a mobile frame, elongated support means mounted on the frame and upwardly extended therefrom, bracket means mounted on the support means for elevational adjustment, means for securing the bracket means in adjusted position on the support means, a wheel chair platform having oppositely disposed open ends and a path of wheel chair travel between the open ends, substantially parallel arms pivotally connected to the bracket means and to the platform on opposite sides of the path mounting the platform on the frame at one side of the support means for concurrent longitudinal reciprocal movement and adjustable elevational movement in parallelism, powered means interconnecting the bracket means and the arms to raise and to lower the platform on the frame, and a counterbalance mounted on the bracket means on the opposite side of the support means from the platform for integral elevational adjustment with the bracket means.

2. A wheel chair hoist comprising a mobile support frame having predetermined forward and rearward end portions; a pair of spaced support members rigidly mounted on the support frame adjacent to the forward end portion and upwardly extended therefrom; brackets mounted on the support members for corresponding adjustable elevational movement; a pair of elevationally spaced substantially parallel arms pivotally mounted on each bracket and rearwardly extended therefrom for pivotal elevational movement as well as adjustable elevational movement with their respective bracket; an elongated platform having opposite ends both adapted to receive and to discharge a wheel chair for rolling movement longitudinally across the platform pivotally mounted between the rearward ends of the arms for elevational movement therewith in horizontal parallelism; powered means connected to the arms for controlled raising of the arms to move the platform upwardly and forwardly for juxtaposition with an elevated surface to and from which a wheel chair can be rolled and controlled lowering of the arms to move the platform downwardly and rearwardly from the elevated surface to a lower surface to and from which a wheel chair can be rolled; and a counterbalance interconnecting the brackets for corresponding elevational movement therewith at the side thereof opposite to the direction of arm extension from the brackets.

3. The hoist of claim 2 in which the counterbalance has a substantially flat upwardly disposed surface intermediate the raised and lowered positions of the platform.

4. The hoist of claim 2 in which the powered means includes hydraulic rams connected to the brackets and having position controlling connection to the arms and in which the counterbalance includes a container containing an hydraulic system connected to the rams, an electric motor having powering connection to the hydraulic system, and a battery having powering connection to the motor whereby the hoist is self contained and the powered means is elevationally adjustable with the arms in response to elevational adjustment of the brackets on the support members.