DE20302374U1 - Motor powered cable scissor lift height adjustment for table or bench - Google Patents

Abstract

A height-adjustable table or bench has a scissor-lift mechanism with a fixed leg (16) and a sliding leg (18) whose base (48) is attached to a cable (46). The cable (46) free length is regulated esp. by a motor (42) powered winding mechanism (44).

Description

TER MEER STEINMEISTER & PARTNER GBR PATENT ATTORNEYS - EUROPEAN PATENT ATTORNEYS

Dr. Nicolaus ter Meer, Dipl.-Chem. Helmut Steinmeister, Dipl.-1ng.

Peter Urner, Dipl.-Phys. Manfred Wiebusch

Gebhard Merkle, Dipl.-Ing. (FH)

Mauerkircherstrasse 45 Artur-Ladebeck-Strasse

D-81679 MUNICH ' D-3361 7 BIELEFELD

FLE P02 / 03 / G St/zs February 13, 2003

Flexlift-Hubgeräte GmbH

Eckendorfer Str. 115

33609 Bielefeld

SCISSOR LIFT TABLE

Flexlift-Hubgeräte GmbH ·&Sgr;· ' FLeW/«$i"G *··**··* February 13, 2003

SCISSOR LIFT TABLE

The invention relates to a scissor lift table with a lower frame and an upper frame, which can be raised and lowered by pairs of scissors arranged between the two frames, which pairs of scissors comprise scissor links which cross one another in a pivot axis and which are each slidably connected to the lower frame and the upper frame in loose bearings and by centering struts which are each pivotally connected to the upper frame or lower frame and/or to one of the scissor links and are secured against lateral displacement with respect to the frames by the centering struts, with a drive which comprises a traction means for raising and lowering the pairs of scissors.

Scissor lift tables of this type are known, for example, from DE 33 31 872 Al or DE 604 156. In the known scissor lift tables, chains, ropes, wire ropes or even belts are used as traction devices. In these known solutions, the guidance of the traction devices is sometimes relatively complicated. The traction devices are connected, among other things, to spreading devices that allow the scissor links to be raised from the completely flat position over the first part of the lifting movement. This requires relatively complicated guidance of the traction devices, which can lead to malfunctions and be subject to increased wear.

The invention is based on the object of creating a scissor lift table of the type mentioned above, which is particularly simple in construction and less susceptible to wear.

This object is achieved in a scissor lift table of the type mentioned at the outset in that the drive comprises a winding shaft attached to the lower or upper frame and driven by a motor, onto which a traction means can be wound, which extends from the winding shaft to the end region of the scissor link guided by floating bearings on the corresponding frame, which can be erected by the pulling effect of the traction means.

Since the motor with the winding shaft is firmly attached to the lower frame or upper frame

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is attached to which the two corresponding ends of the scissor links are also guided so that they can move by means of loose bearings, and since a joint displacement of both loose bearings in the longitudinal direction of the frame is prevented by the centering struts, the pulling effect results in the scissor link connected to the pulling device and thus also the other scissor link being straightened up.

As usual, the upper frame can support a table top that forms a lifting platform. However, the upper frame can also support working tools, assembly devices, containers and the like, as required by the specific production process.

If the aim is to use a motor with the lowest possible torque, the traction means can, according to a preferred embodiment, be guided around a deflection roller at one of the lower end areas of the scissor links to the corresponding end area of the other scissor link and secured there. In this case, the lifting speed is halved and, due to the pulley effect, the torque required on the winding shaft is halved.

Preferably, a band or belt is used as the traction device, which allows it to be wound onto a winding shaft. In this way, the individual layers on the winding shaft are placed on top of each other, so that the winding diameter increases. As a result, the speed at which the band or belt is drawn in increases with the increasing lifting movement, while the torque of the motor decreases due to the increase in the diameter of the winding shaft. However, this is not a problem, since the tensile forces that have to be applied at the start of the erection process are highest due to the unfavorably small angle between the lower end areas of the scissor links that are to be pulled in and the course of the traction device, while these required tensile forces can decrease continuously as the lifting movement continues.

The motor with the winding shaft can be mounted in any position on the lower or upper frame, both between the floating bearings and outside the floating bearings. In any case, it is able to move by pulling action with the help of the pulling

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by means of one of the scissor links supported by floating bearings so that it is erected.

In a further advantageous embodiment, the traction means is guided from the winding shaft around a deflection roller at the end region of the corresponding scissor link and is fastened at its end to the frame.

In this and the first embodiment, there is an increased load on the centering struts. The second embodiment is therefore to be regarded as preferred.

Insofar as the present invention provides the possibility of attaching the entire drive to the subframe and in the present context it is stated that parts, in particular the drive unit or the end of the traction means are attached to the subframe, these can also be attached directly to the hall floor if the scissor lift table is fixed in place on a hall floor.

In the following, preferred embodiments of the invention are explained in more detail with reference to the accompanying drawings.

Fig. 1 is a schematic side view showing a first embodiment
the invention;

Fig. 2 shows a second embodiment of the invention;

Fig. 3 shows a third embodiment of the invention.

Fig. 1 shows a side view schematically of a first embodiment of a scissor lift table according to the invention with an upper frame 10 and a lower frame 12. The upper frame 10 is supported on the lower frame 12 by a pair of scissors 14, which is composed of two crossing scissor members 16, 18, which are pivotally connected to one another in a pivot axis 20 directed perpendicular to the plane of the drawing.
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In a manner not shown, there are at least two pairs of scissors arranged perpendicular to the plane of the drawing between the lower frame 12 and the upper frame 10, so that the upper frame 10 is supported in a stable manner and does not tip over. In the following, only the scissor links 1, 18 visible in the drawing will be discussed. The same applies to the scissor links of the other pair of scissors.

The scissor members 16, 18 are slidably guided on the upper frame 10 and the lower frame 12 by loose bearings 22, 24 and 26, 28. The loose bearings can comprise rollers which can slide to the left and right with respect to Fig. 1 in guides (not shown) on the upper frame 10 and the lower frame 12 when the scissors are raised or lowered.

To ensure that the pair of scissors 14 as a whole cannot be moved laterally to the right and left in relation to the lower frame and the upper frame in relation to Fig. 1, centering struts 30, 32 are provided which are pivotably mounted on the upper frame 10 and lower frame 12 in axes 34, 36 and pivotably mounted on the scissor link 18 in further axes 38, 40. Since these axes 34, 36, 38, 40 are formed by fixed bearings which, in contrast to the floating bearings 22, 24, 26, 28, cannot be moved along the frame to the right and left in the drawing, the centering struts 30, 32 determine the position of the pair of scissors, insofar as this concerns this as a whole, represented for example by the central pivot axis 20, in relation to the two frames 10, 12.

In the example shown, a gear motor 42 is attached to the lower frame 12 to the right outside the two floating bearings 26, 28, from which a winding shaft 44 emerges perpendicular to the plane of the drawing. A traction device 46 extends from this winding shaft 44, which, as explained, is preferably formed by a band or belt that can be wound up. In the embodiment shown, the traction device 46 runs to a fixed point 48 in the lower end region of the scissor link 18. It can be seen that when the traction device 46 is wound up, the lower end region of this scissor link 18, which runs from bottom left to top right in the drawing, is pulled towards the winding shaft 44. This leads to the scissor link 18 being erected. This

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At the same time, the pivot axis 20 and, via this, the other scissor link 16 are raised. The two loose bearings 22 and 24 on the upper frame slide towards each other and the upper frame is raised. A lateral displacement of the pair of scissors in relation to the lower frame or upper frame is prevented by the two centering struts 30 and 32.

In Fig. 2, the same parts are shown as in Fig. 1, with minor differences, so that only the same reference numbers are entered and a repeated description of all details can be omitted.

In the second embodiment according to Fig. 2, the traction means is not connected to the lower left end of the scissor link 18 at a fixed point 48, but is guided around a deflection roller 50 at the lower end of this scissor link and finally connected to the other floating bearing 28. In this way, the two floating bearings 26, 28 are pulled together by the traction means 46. The way in which the traction means 46 is guided causes a pulley effect to occur, which reduces the erection speed of the pair of scissors and also reduces the torque required on the winding shaft. Furthermore, the embodiment shown in Fig. 2 has the advantage that the centering struts 30, 32 are only loaded to a lesser extent than in the embodiment according to Fig. 1.

The third embodiment according to Fig. 3 again corresponds largely to that of Figs. 1 and 2, so that here too only the differences will be described. In this embodiment, the traction means 46 is also guided around the deflection roller 50 already shown in Fig. 2 and is attached to the frame with its overshooting end in a holding point 52. In this embodiment, the two centering struts 30, 32 are again subjected to greater load than in the second embodiment.

The drive system according to the invention is located on the lower frame 12 in the three embodiments described in more detail and shown in the drawing, but can also be attached to the upper frame 10. However, it is fundamentally disadvantageous that with this attachment to the upper frame, the weight of the drive must be raised with the lifting movement. The arrangement of the drive on the lower frame shown is therefore to be considered preferred.

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Compared to the known embodiments, the drive device according to the invention has the advantage that it does not require any traction means guided up and down over the scissor cross, where the traction means can get caught or cause other problems. In the embodiments described with reference to the drawing, two loose bearings 22, 24 and 26, 28 are provided on both the upper frame 10 and the lower frame 12. The invention is tailored so that on the side on which the drive is located, both scissor links are slidably mounted at their ends in loose bearings. This can also be the case on the other frame, provided that a centering strut of the type of struts 30, 32 is provided here. However, it is also possible to provide only one loose bearing instead of the centering strut on the other frame, which is not connected to the drive, and a fixed bearing instead of the second loose bearing.

Greater lifting heights can be achieved by adding at least one additional pair of scissors to the pair of scissors shown in the present description. Such double scissor lifts are also known per se.

Claims (5)

1. Scissor lift table with a lower frame ( 12 ) and an upper frame ( 10 ), which can be raised and lowered by pairs of scissors ( 14 ) arranged between the two frames ( 10 , 12 ), which pairs of scissors comprise scissor links ( 16 , 18 ) crossing each other in a pivot axis ( 20 ), which are each slidably connected to the lower frame ( 12 ) and/or the upper frame ( 10 ) in floating bearings ( 22 , 24 , 26 , 28 ) and are secured against lateral displacement in relation to the frames ( 10 , 12 ) by centering struts ( 30 , 32 ), which are each pivotably connected to the upper frame or lower frame and/or to one of the scissor links ( 16 , 18 ), with a drive ( 42 , 44 ), which comprises a traction means for raising and lowering the pairs of scissors, characterized in that the drive ( 42 , 44 ) comprises a winding shaft ( 42 ) attached to the lower or upper frame ( 10 , 12 ) and driven by a motor ( 42 ), onto which a traction means ( 46 ) can be wound, which extends from the winding shaft to that end region of the scissor member ( 18 ) guided by floating bearings ( 26 ) on the corresponding frame ( 12 ), which can be erected by the traction effect of the traction means. 2. Scissor lift table according to claim 1, characterized in that a deflection roller ( 50 ) is attached to the end region of the scissor link ( 18 ), and that the traction means ( 46 ) runs around the deflection roller ( 50 ) to the end region of the other scissor link ( 16 ) guided on the corresponding frame ( 12 ) through loose bearings ( 28 ). 3. Scissor lift table according to claim 1, characterized in that a deflection roller ( 50 ) is attached to the end region of the scissor member ( 18 ), and that the traction means ( 46 ) runs around the deflection roller ( 50 ) to a fixed point ( 52 ) on the corresponding frame. 4. Scissor lift table according to claims 1 to 3, characterized in that the traction means ( 46 ) is a flat band or belt. 5. Scissor lift table according to claim 4, characterized in that lateral guide discs are provided on the winding shaft ( 42 ) for supporting a tape roll.