Patent Application
20060180403
The field of the invention is scissor lifts.
Scissor lifts have been widely used across many applications for many years. Among other things, such lifts have been used to raise automobiles and other heavy equipment, people, building components, supplies, structural components, and to provide scaffolding, work stands, patient beds and so forth. Operation of the scissor must be operated in some manner, and in some instances the scissor is operated using a screw drive. Examples in the patent literature include U.S. Pat. No. 6,719,282 to Frank (April 2004); U.S. Pat. No. 6,684,443 to Thomas et al. (February 2004); US20040005961 to lund et al. (January 2004); U.S. Pat. No. 6,655,875 to Pignato (December 2003); U.S. Pat. No. 5,996,961 to Johnson (December 1999); and U.S. Pat. No. 5,593,137 to Johnson (January 1997); U.S. Pat. No. 5,105,915 to Gary (April 1992); and U.S. Pat. No. 3,817,346 to Wehmeyer (June 1974). This and all other referenced patents and applications are incorporated herein by reference in their entirety. Where a definition, or use of a term in a reference incorporated by reference, is inconsistent or contrary to the definition of that term provided herein, the definition of that term provided herein applies and the definition of that term in the reference does not apply.
Despite these varied uses, and the considerable experience of decades of use, there are still problems associated with screw-type scissor lifts. One problem is that the screw mechanism tends to bind. Another problem is that there is a very significant mechanical disadvantage-working against extension of the scissor mechanism in a compressed position. In prior art scissors, the retraction must usually provide at least a 10° angle between the screw drive and the lowest arm of the scissors. That problem can be resolved by limiting the extent to which the scissor mechanism can retract, but then the mechanism is not so compact as one might prefer.
Thus, there still remains a need for improvements in screw-type scissor lifts.
The present invention provides apparatus, systems and methods in which a scissor lift for lifting a payload, comprises a first pair of scissored arms disposed to lift the payload and an energy storage device disposed to store energy as the payload is lowered, and provide further lift to the payload as the payload is raised.
At a fully retracted position, the scissored arms define a support angle of at least 150°, more preferably at least 165°, still more preferably at least 175°, and most preferably 180°. At the extreme of 180°, this corresponds to an angle of 0° between the screw drive and the lowest arm of the scissors, which means that such scissor lifts can be considerably more compact than prior art lifts.
In another aspect of preferred embodiments, a bearing is used at a pivot joining the first and second arms, with hardened washers on either sides of the bearing. These features help reduce side to side sway of the scissor mechanism, and therefore of the payload. In especially preferred embodiments the bearing is sufficiently stiff to restrict side to side movement of the payload such that movement of the payload under operation of the lift is substantially planar.
In still another aspect of preferred embodiments, a screw, piston, cable, chain, rack and pinion or other actuator is mechanically coupled to one of the scissor arms to provide motive force to the lift. In especially preferred embodiments the actuator drives both arms of the lowest (or only) pair of scissor arms.
There must be some source of motive force that drives the actuator, and in preferred embodiments that source comprises an electric motor.
The energy storage device is preferably a helical wire spring, but can alternatively be any suitable spring, whether helical or non-helical, having thin or thick wires, and whether constructed of metals, non-metals, or a combination. In still other embodiments the energy storage device could be a flat spring, a gas piston, or even a piece of rubber or other elastomeric mass.
Contemplated lifts can comprise more than one pair of scissored arms, either laterally adjacent to one another, or more likely stacked on top of one another. At the lower end of the lift, the bottom (or only) pair of scissors is preferably coupled to a substantially immovable base at spaced apart first and second pivots, and a connector that transmits motive force to the scissors is restricted by a guide to movement substantially within a single plane. At the upper end of the lift, the top (or only) pair of scissors is preferably coupled to a movable platform at spaced apart third and fourth pivots. The moveable platform directly or indirectly supports the payload.
Various objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of preferred embodiments of the invention, along with the accompanying drawings in which like numerals represent like components.
In
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The binding problem alluded to above is resolved by using a thrust bearing on one end, but not on the other. The mechanical disadvantage problem is resolved by using a spring, gas cylinder, fluid spring, or other biasing element that adds additional force when the scissors is in a highly retracted configuration. The biasing element can be positioned as shown in the figures, or in many other configurations that provide a similar function. The spring can even, for example, be disposed about the screw. In preferred embodiments the biasing element provides and additional force up to 10 times that provided by the screw, and allows screw drive/scissors angles of 5° or even less. Currently preferred springs provide force of 50 pounds per inch, and are between 3″ and 12″ long. In some embodiments springs or different force profiles can be interchanged, and can be color coded or marked in some other manner to accommodate different desired lift characteristics.
The lift is in communication with a drive controller 161. The drive controller 161 can be used to control and/or provide power to the drive mechanism (not shown) of the lift 410. A preferred drive controller has a transceiver or receiver in order to receive signals from a remote control device. It is further contemplated that a lift can be incorporated into a home appliance center and control of the lift can therefore be accomplished using a computer or other device programmed to control home appliances. Such control can also be accomplished remotely from a distal location, if necessary. It may be desirable for a parent to monitor a child's “T.V. time”, and as such, enhancements can be built into the controller that can prevent the lift and or the projector from operation without authority.
Thus, specific embodiments and applications of a screw scissor lift have been disclosed. It should be apparent, however, to those skilled in the art that many more modifications besides those already described are possible without departing from the inventive concepts herein. The inventive subject matter, therefore, is not to be restricted except in the spirit of the appended claims. Moreover, in interpreting both the disclosure, all terms should be interpreted in the broadest possible manner consistent with the context. In particular, the terms “comprises” and “comprising” should be interpreted as referring to elements, components, or steps in a non-exclusive manner, indicating that the referenced elements, components, or steps may be present, or utilized, or combined with other elements, components, or steps that are not expressly referenced.
This application claims priority to U.S. provisional application Ser. No. 60/642,267 filed Jan. 7, 2005.
| Number | Date | Country | |
|---|---|---|---|
| 60642267 | Jan 2005 | US |
