Mechanical linkage for lifting

摘要

A “hex-plus-X” linkage for lifting applications, comprising a hexagonal assembly, an X assembly, and actuation means. The hexagonal assembly comprises six bars, B1 through B6, pivotally attached end-to-end in a closed hexagonal loop, B1-B2-B3-B4-B5-B6-B1. B1 is a base bar; B4 is a top bar. The X assembly, comprising two bars B7 and B8 pivotally attached to each other, is pivotally and slidably attached to B1 and B4, thereby eliminating two unwanted degrees of freedom from the hexagonal assembly without limiting the size of B1 or B4. The actuation means is pivotally attached at knee joints between B2-B3 and B5-B6. To save space and eliminate tripping hazards, the knee joints are concave, so that B2-B3 and B5-B6 do not protrude. When actuated, the linkage lifts a load by modulating a distance between B1 and B4. Mechanical advantage is high. Slidable joints bear modest loads, minimizing wear. None of B4 is cantilevered.

主权项

1. A mechanical linkage for performing a motion that occurs parallel to an imaginary xy plane of an imaginary Cartesian xyz coordinate system having an imaginary x axis, an imaginary y axis, and an imaginary z axis that define the xy plane as well as an imaginary xz plane and an imaginary yz plane, the linkage comprising
a. a base-bar B1 extending along the x axis, bar B1 having a first end located at a small value of x and a second end located at a larger value of x, b. a first lower V bar B2, c. a first upper V bar B3, d. a top bar B4 whose size projected upon the xz plane defines a top footprint, e. a second upper V bar B5, f. a second lower V bar B6, g. a first X bar B7 h. a second X bar B8, i. a first joint J1 at which the first end of bar B1 is pivotally attached to a first end of bar B2, j. a second joint J2 at which a second end of bar B2 is pivotally attached to a first end of bar B3, k. a third joint J3 at which a second end of bar B3 is pivotally attached to a first end of bar B4, l. a fourth joint J4 at which a second end of bar B4 is pivotally attached to a first end of bar B5, m. a fifth joint J5 at which a second end of bar B5 is pivotally attached to a first end of bar B6, n. a sixth joint J6 at which a second end of bar B6 is pivotally attached to the second end of bar B1, o. a seventh joint J7 at which a first end of bar B7 is pivotally attached near the first end of bar B1, p. an eighth joint J8 at which a first end of bar B8 is pivotally attached near the first end of bar B4, q. a ninth joint J9 at which a second end of bar B7 is pivotally and slidably attached near the second end of bar B4, r. a tenth joint J10 at which a second end of bar B8 is pivotally and slidably attached near the second end of bar B1, and s. an eleventh joint J11 at which bar B7 is pivotally attached to bar B8 t. actuation means having a first end that is pivotally attached at joint J5 and a second end that is pivotally attached at joint J2, the actuation means being capable of increasing and decreasing a knee-to-knee distance between joints J2 and J5 by applying thereto oppositely directed actuation forces of magnitude F,whereby, by varying the knee-to-knee distance using the actuation means, a distance H measured parallel to the y axis between bars B1 and B4 is caused to undergo a modulation in which the distance H is increased or decreased despite externally applied, oppositely directed forces of a magnitude P that act upon bars B1 and B4 to oppose the modulation, the modulation of distance H being thereby accomplished with a number of advantages: first, the linkage has only one degree of freedom, allowing modulation of the distance H, and consequently the linkage avoids unwanted, extraneous degrees of freedom; second, such extraneous degrees of freedom are prevented in a manner that does not limit the size of the top footprint; third, the linkage has a relatively high mechanical advantage, defined as a ratio P/F, thereby allowing the modulation of distance H to occur, for a given value of the applied force P, with a relatively small value of the actuation force F; fourth, the slidable joints J9 and J10 transmit forces in typical operation of the linkage that are relatively small compared to the applied force P, thereby minimizing wear at these joints; and fifth, the top bar B4 is substantially fully supported across the top footprint, avoiding substantial cantilevered portions thereof.