Scissors lift for a wheelchair

Abstract

The present invention relates to a scissors lift comprising a bottom frame, a top frame and a scissors mechanism arranged between the bottom frame and the top frame to displace the bottom frame and the top frame relative to each other by transfer of an actuation force. The scissors mechanism comprises a central hollow scissors arm delimited between opposite scissors arm surfaces, wherein the central hollow scissors arm has a bottom pivotal connection connecting it to the bottom frame and a top pivotal connection connecting it to the top frame. Further, the mechanism comprises two passive scissors arms being pivotally connected to the bottom frame and pivotally connected to the top frame. Each of the two passive scissors arms are pivotally connected to the central hollow scissors arm on the opposite scissors arm surfaces of the central hollow scissors arm. Further, the scissors lift comprises a motor providing said actuation force, said motor located between said opposite scissors arm surfaces of said central hollow scissors arm. Thereby, the motor may be protected and at least partially enclosed by the scissors lift and even by the central hollow scissors arm, allowing a safer and/or more easily maintained scissors lift.

Claims

1. A scissors lift comprising a bottom frame, a top frame and a scissors mechanism arranged between said bottom frame and said top frame to displace said bottom frame and said top frame relative to each other by transfer of an actuation force, wherein said scissors mechanism comprises: a central hollow scissors arm delimited between opposite scissors arm surfaces, wherein said central hollow scissors arm has a bottom pivotal connection connecting it to said bottom frame and a top pivotal connection connecting it to said top frame, and two passive scissors arms being pivotally connected to said bottom frame and pivotally connected to said top frame, wherein each of said two passive scissors arms being pivotally connected to said central hollow scissors arm on said opposite scissors arm surfaces of said central hollow scissors arm, and wherein said scissors lift comprising a motor providing said actuation force, said motor located between said opposite scissors arm surfaces of said central hollow scissors arm.

2. A scissors lift according to claim 1, wherein said central hollow scissors arm is a U-profile, where opposite scissors arm surfaces are interconnected at one end.

3. A scissors lift according to claim 1, wherein said central hollow scissors arm is a U-profile, where opposite scissors arm surfaces are interconnected at both ends.

4. A scissors lift according to claim 1, wherein said scissors lift further comprises a stroke mechanism for transferring said actuation force into displacing said bottom frame and said top frame relative to each other, said stroke mechanism comprising a lever, said lever comprises a body comprising: an actuation joint being displaceable by said actuation force, and a fulcrum joint connecting said lever body to said bottom frame or said central hollow scissors arm; said lever further comprises: a load joint connected to said body through a load element, said load joint connecting said lever to said central hollow scissors arm or said bottom frame, a lever distance, from said fulcrum joint to said actuation joint and a load distance, from said fulcrum joint to said load joint, wherein said stroke mechanism enables a stroke, said stroke being from a substantially closed state of said scissors lift, wherein said stroke at least initially decreases said lever distance and/or increases said load distance.

5. A scissors lift according to claim 4, wherein said stroke at least initially enables increasing said load distance.

6. A scissors lift according to claim 4, wherein said stroke at least initially enables decreasing said lever distance.

7. A scissors lift according to claim 4, wherein said lever comprises a telescopic end, whereby said stroke at least initially enables decreasing said lever distance.

8. A scissors lift according to claim 4, wherein said lever comprises a curved guide guiding said load joint, enabling a movement of said load joint away from said fulcrum joint at least initially during said stroke, whereby said stroke at least initially enables increasing said load distance.

9. A scissors lift according to claim 4, wherein said load element comprises said load joint whose position is fixed relative to said fulcrum joint and wherein said load element is connected to said knee joint and connected to said load joint, where the leg element rotates around said knee joint and where this rotation enables lengthening the load distance during at least an initial length of said stroke.

10. A wheelchair comprising a scissors lift according to claim 1.

Description

LIST OF FIGURES

(1) The scissors lift will be described in more detail below with references to exemplary embodiments shown in the figures wherein,

(2) FIG. 1A is a perspective view of a scissors lift according to the invention,

(3) FIG. 1B illustrates a side view of a scissors lift according to the invention,

(4) FIG. 2A-2D illustrates an opening procedure of a scissors lift according to the invention,

(5) FIG. 3 illustrates an alternative embodiment of a scissors lift according to the invention.

(6) FIG. 4 illustrates an embodiment using a guide according to the invention.

(7) FIG. 5 illustrates an embodiment using a knee-joint according to the invention.

GENERAL DESCRIPTION

(8) FIG. 1A is a perspective view of a scissors lift 100 according to the invention. A central hollow scissors arm 101 comprises the motor and a stroke mechanism not shown, flanked by two passive scissors arms 103 and 103 at opposite scissors arm surfaces. The scissors arms 101, 103, and 103 are pivotally connected at their mutual crossing through a scissors arms joint 108. The bottom frame 105 comprises a first pivot point 104 in one end of the frame. Said first pivot point 104 connects the central hollow scissors arm 101 to said bottom frame 105, whereas the passive scissors arms 103 and 103 are connected to the bottom frame through slidable bottom pivot points 106 and 106, which are mounted on displaceable elements along bottom rails 107 and 107.

(9) The bottom frame 105 is a rectangular profile, i.e. a profile having two parallel arms connected in their ends through two shorter elements perpendicular to said longer arms. The bottom frame 105 may also be a U-shaped profile, comprising a connection between said parallels in only one end.

(10) FIG. 1B is a side view of the scissors lift 100 according to the invention. The side view originates from a cut in between the two passive scissors arms 103, 103, in a direction parallel to the plane of the scissors arms 101, 103, and 103. The central hollow scissors arm 101 houses a motor 110 and a stroke mechanism 111-120 for providing a stroke that lifts the top frame. The remaining two scissors arms 103, 103 are passive, such that their movement is determined through the movement of the central hollow scissors arm. A top frame 109 is shown in this embodiment, where the central hollow scissors arm 101 is pivotally connected to a displaceable element along the rails of the top frame 109, and the passive scissors arms 103 and 103 are connected to a fixed pivot point on the top frame 109.

(11) A motor 110 is adapted to rotate a threaded rod 111, displacing a threaded engaging element 112 fixed to an actuated element 114 along a threaded rod. The actuated element 114 moves along an actuation rail 113, parallel to the central hollow scissors arm.

(12) A lever 115 is pivotally connected to the central hollow scissors arm in a fulcrum joint 116, pivotally connected to the actuated element 114 through a telescopic end 117, and an knee joint 118 in an opposite, distal end.

(13) The lever 115 slightly bends at the fulcrum joint 116 mounted on the central hollow scissors arm 101. Further, the lever 115 is connected to the bottom frame through a knee joint 118, mounted to a load element 119 connected to the bottom frame 105 through a load joint 120. The load element guides the transfer of force from said lever 115 to said load joint 120.

(14) In FIG. 2A, the scissors lift is shown in a closed state. In this state, the threaded engaging element 112 and the actuated element 114 connected to said threaded engaging element 112 is furthest away from the motor 110. Thereby, the telescopic end 117 is extended to compensate for the longer distance between the fulcrum joint 116 on the central hollow scissors arm 101, and the actuation joint 121 of said telescopic end 117 to the actuated element 114. Further, the long distance between the two joints 116 and 121 of the telescopic end 117 allows for a greater leverage through the lever 115 in the beginning of the motion from a closed state to an open state. The knee joint-structure 118-120 is fully folded, and the bent nature of the lever 115 allows for a slimmer profile in a closed state.

(15) In FIG. 2B, the motor 110 has rotated the threaded rod 111, bringing the threaded engaging element 112, and thereby the actuated element 114, slightly closer to the motor 110. The telescopic end 117 is now retracted, to accommodate the decreased distance between the fulcrum joint 116 and the actuation joint 121. The movement of the actuated element 114 has rotated the lever 115, pushing against the knee joint, which cannot move further downwards, instead translating the force into causing the central hollow scissors arm 101 to be slightly raised through the fulcrum joint 116 connecting it to said lever 115, further displacing the frames relative to each other.

(16) In FIG. 2C, the threaded engaging element 112 is even closer to the motor 110. The telescopic end 117 is still retracted, but the lever 115 has been pulled further upwards, through the actuation joint 121, executing a rotation in the fulcrum joint 116, further opening the knee-joint, thus putting a distance between the fulcrum joint 116 and the load joint 120, thereby lifting the central hollow scissors arm 101.

(17) In FIG. 2D, the threaded engaging element 112 is as close to the motor 110 as mechanically allowed. Thereby, the actuated element 114 has pulled the telescopic end 117 to its maximum height, thereby executing a pull in the lever 115, such that said lever further executes a pull in the pivotal connection 116, connected to the central hollow scissors arm 101. Thereby, said scissors arm 101 has reached is maximum height, ie displaced the bottom frame 105 and the top frame from each other as much as is mechanically allowed. Through said scissors arms joint 108, the passive scissors arms 103 and 103 have likewise reached their maximum angle with respect to the bottom frame 105.

(18) In all the above cases, the pull is supported through the knee joint-structure 118-120, connecting the stroke mechanism to the bottom frame 105 through the load joint 120. Further, in all the above cases, the passive scissors arms 103 and 103 have likewise increased their angle with respect to the bottom frame 105, as said passive scissors arms 103, 103 are pivotally connected to the central hollow scissors arm 101 through the scissors arms joint 108. The passive scissors arms 103, 103 are further able to move freely along the bottom rail 107 through slidable bottom joints 106, 106.

(19) FIG. 3 shows another embodiment of a scissors lift according to the invention. The general construction is unchanged from the first embodiment, but the stroke mechanism is modified. A linear actuator 310 is adapted to extend or retract a rod 311. At the end of the rod 311, an element 312 is mounted and further connected to the actuated element 114, to which the stroke mechanism disclosed in the first embodiment applies and works likewise.

(20) FIG. 4 shows another embodiment of a scissors lift 400 according to the invention. The general construction of the scissors lift 400 is similar to the first embodiment 100, but the stroke mechanism is different. In this embodiment, a linear actuator 410 is mounted to the bottom frame 105, and the actuator 410 provides a push through an actuator rod 411 connected at the actuation joint 421, to a lever 415. The lever element 415 comprises a load element being a guide 431, guiding the movement of a load joint 420 and fixating the movement of the lever around this load joint 420. Thereby, the load element 431 guides the translation of force from the lever 415 to the load joint 420.

(21) The load joint 420 is fixed on the central hollow scissors arm 101, protruding into the load element 431, limiting the motion of the lever element 415 to the shape of said load element 431. The lever element 415 is pivotally connected to the bottom frame 105 through a fulcrum joint 416, such that a push provided by the actuator rod 411 causes the lever 415 to move along the load element 431, kept in place by the fulcrum joint 416, and by being further pivotally connected to the bottom frame 105, the push by the actuator rod 411 causes the lift to open by displacing the load joint 420 relative to the fulcrum joint 416, increasing the angle between the bottom frame and the scissors arms 101, 103, and 103. A cavity 432 in the wall of the central hollow arm 101 is provided to allow access of the bottom frame for the fulcrum joint 416.

(22) FIG. 5 shows another embodiment of a scissors lift 500 according to the invention. The general construction of the scissors lift 500 is similar to the first embodiment 100, but the stroke mechanism is different. In this embodiment, a linear actuator 510 is mounted to the bottom frame 105, being capable of providing a push or a pull through the actuation joint 521. The actuation joint 521 connects to a leg of a V-shaped lever 515. Further, the lever has a fulcrum joint 516 at a bend in the lever, around which the leverage of the motor rotates. A shorter leg is provided with a knee-joint. A load element 519 is connected between the knee joint 518 and a load joint 520 mounted on the central hollow scissors arm 101. When the linear actuator 510 extends the actuation rod 513, the rotation provided to the lever 515 causes its distal end to transfer the rotation through the knee joint 518 and onto the load joint 520 mounted on the central hollow scissors arm 101, finally causing the angle between the bottom frame and the scissors arms 101, 103, and 103 to increase. A cavity 532 in the wall of the central hollow arm 101 is provided to allow access of the bottom frame for the fulcrum joint 516.

REFERENCE NUMBERS

(23) 100 scissors lift 101 central hollow scissors arm 103, 103 passive arms 104 first pivot point 105 bottom frame 106, 106 slidable bottom joints 107 bottom rail 108 scissors arms joint 109 top frame 110 motor 111 threaded rod 112 thread engaging element 113 actuation rail 114 actuated element 115 lever 116 fulcrum joint 117 telescopic end 118 knee joint 119 load element 120 load joint 121 actuation joint 310 linear actuator 311 rod 400 scissors lift 410 linear actuator 411 actuator rod//411 415 lever 416 fulcrum joint 419 load element 420 load joint 421 actuation joint 432 cavity 500 scissors lift 510 linear actuator 515 lever 516 fulcrum joint 518 knee joint 519 load element 520 load joint 521 actuation joint 532 cavity