WO2006050735A1

WO2006050735A1 - A lifting column

Info

Publication number: WO2006050735A1
Application number: PCT/DK2005/000723
Authority: WO
Inventors: Henning Kristensen; Jens Jørgen NIELSEN; Norbert Klinke; Christian Platz
Original assignee: Linak A/S
Priority date: 2004-11-12
Filing date: 2005-11-11
Publication date: 2006-05-18
Also published as: EP1809142A1

Abstract

A lifting column comprises a guide having an outermost section and an innermost section as well as at least one intermediate section, said sections being arranged to be mutually telescopic, with slides arranged between the sections, and the column moreover comprises a drive device for causing the telescopic movement of the guide. For simultaneous movement of the at least one intermediate section and the outermost section, the lifting column comprises independent means for synchronized control of the intermediate section relative to the outermost and innermost sections.

Description

A lifting column

The present invention relates to a lifting column comprising a guide having an outermost section, an innermost section as well as at least one interme- diate section, said sections being arranged to be mutually telescopic, with slides arranged between the sections, and comprising a drive device for causing the telescopic movement.

In order to explain the invention, the disclosure will be based on lifting columns having three members for height-adjustable tables, where a dis¬ tinction is made between synchronous and asynchronous lifting columns. In the synchronous lifting columns, the intermediate section of the guide is forcibly controlled to move simultaneously with the innermost section, i.e. at the same time as the innermost section extends out of the intermediate section, this extends out of the outermost section, just as they retracts in the same order. In an asynchronous lifting column, the intermediate section is freely between the outermost and innermost sections. The innermost section extends first, and when this has been extended fully, the intermediate section begins to extend, as the innermost section, by mutual abutment, brings along the intermediate section. The problem is, however, that friction in the slides between the individual sections interferes in a disturbing manner such that the intermediate section may unintentionally hang on the innermost section, thereby producing an arbitrary pattern of movement. If, e.g., the intermediate section hangs, this will be seen to run out first, and then the innermost section will be seen to extend out of the intermediate section. The pattern of movement becomes particularly inelegant if the friction suddenly fails and the intermediate section slides down, or the intermediate section is suddenly caused to hang at the outermost section, whereby the intermediate section is moved in steps. In a synchronous lifting column, the drive device is constructed such that the intermediate section may be secured to it and be moved in synchronism with the innermost section.

An important, if not essential, aspect of the furniture business is the design. It is inherent to the furniture business to create individual designs to a greater or smaller degree. Authors of furniture design do not want to be bound in advance by the design of the lifting columns, which, since they constitute the table legs of the table, are an important element of the design of the table. In fact, tables are provided where the lifting columns as a whole are concealed, which gives strong table legs, as the individual design resides outside the lifting column. Others take the full step with individually designed sections, and rely on only using the drive device from the lifting column manufacturer. This, however, is not a simple task, since, at any rate, it requires adaptation to the individual designs. This, of course, adds to the costs and present problems in terms of production and logistics.

The object of the invention is to overcome the problems outlined above.

This is achieved according to the invention in that the lifting column com¬ prises independent means for synchronized control of the at least one in- termediate section relative to the outermost and innermost sections. A clear division of the lifting column into a guide, a drive device and synchroniza¬ tion means provides greater freedom with respect to design and construc¬ tion. Thus, in the construction, high priority may be given to the primary functions of each of the three parts, it being merely borne in mind that the three parts must finally be capable of being built together.

Further features of the invention will appear from the following description of several concrete embodiments of the invention, as defined in the de¬ pendent claims.

In the drawing: Fig. 1 shows a sitting/standing table shown with a transparent tabletop,

fig. 2 shows a partly exploded view of a synchronization means for forcible control of the intermediate section in the lifting columns for the table,

fig. 3 shows a sketch of a synchronization means based on racks and a wire,

fig. 4 shows a sketch of a variant of the embodiment of fig. 3, in which the wire is replaced by a plurality of gear wheels,

fig. 5 shows sketches of an embodiment of the synchronization means with two racks in engagement with a gear wheel,

fig. 6 shows sketches of an embodiment with racks mounted on the sides of the outermost section and the innermost section, re- spectively,

fig. 7 shows sketches of an embodiment of the synchronization means based on spindles,

fig. 8 shows a sketch of an embodiment with a synchronization means with a motor-driven spindle,

fig. 9 shows sketches of a synchronization means based on rollers between the sections,

fig. 10 shows sketches of an embodiment of the synchronization means based on wires,

fig. 11 shows sketches of an embodiment of the synchronization means based on springs, and

fig. 12 shows a sketch of an exploded column, where the synchroniza¬ tion is carried out by threads between the individual sections.

Fig. 1 of the drawing shows a sitting/standing table with a lifting column at each side. It is observed that the tabletop is shown to be transparent. The lifting column consists of a guide with three members, viz. an outermost section 1 , and intermediate section 2 and an innermost section 3 arranged telescopically inside each other, with slides arranged in the gaps between the individual sections. The lower end of the outermost section 1 is secured to a foot 4, while the upper end of the innermost section 3 is secured to the lower side of the tabletop 5. To cause the telescopic movement, there is a drive device based on a solid spindle and a hollow spindle driven by an electric motor via a gear transmission, typically a worm gear.

A first embodiment of the invention is shown in fig. 2. A synchronization means is provided for forcibly controlling the intermediate section 2, com¬ prising a chassis in the form of a U-rail 7 of bent sheet metal strip. Upwardly and downwardly in the rail, there is a deflection wheel 8, 9 around which a wire 10 is passed. One end of the wire is secured to the innermost section by a bracket 11. From there, the wire runs around the lowermost wheel 9 and up around the uppermost one 8 and down again around the lowermost one and is finally secured by a bracket 12 to the wire run extending be¬ tween the two wheels. A rod 13 is secured with one end to the same bracket 12, and the lower end of the rod may be screwed firmly on to a bottom plate in the outermost section 1 by a bracket 14. The synchroniza¬ tion means, as a whole, may be secured to the central section 2. For this purpose, a plate member 15 is welded in the lower end of the intermediate section 2, and a block 16 having a threaded hole is provided in the lower¬ most end of the U-rail 7 so that the means may be screwed firmly on to the plate member. The assembly is simple, since it may be performed from the ends of the individual sections. When the drive device is activated for ex¬ tending the innermost section, a pull is applied to the wire 1O, whereby it is attempted to press the rod 13 downwards, but since it is secured to the lowermost section, the U-rail 7 and thereby the intermediate section 2 will rise instead. Hereby, the intermediate section 2 will be extended syn- chronously with the innermost section. As will appear, the synchronization means may be made quite slender, since they are not to carry the load on the column.

For the sake of completeness, it should be mentioned that WO 03/003876 to Linak A/S discloses a drive unit for a lifting column based on an endless element with two rods. Here, the drive unit per se causes the central sec¬ tion to be synchronized. The synchronization means according to the in¬ vention are intended for use in connection with an independent drive de¬ vice, e.g. as illustrated in fig. 5 of WO 02/39848 to Linak A/S, said drive de- vice being based on a hollow spindle in cooperation with a solid spindle. WO 01/78556 to Okin Gesellschaft fur Antriebstechnik GmbH & Co. KG. discloses a lifting column like the latter with spindles, where the central section is connected with the hollow spindle. An excellent idea, but the con¬ figuration of the guide is hereby tied to the drive device, wh ich is exactly what the furniture business does not want.

A variant of the above-mentioned configuration of the synchronization means is that the wire 10 is endless, and that both runs of it are connected with a rod, so that also the innermost section 3 of the column is connected with the wire by a rod. When the innermost section 3 is extended, the pull on the rod connected therewith will pull the wire, and, thereby, the rod on the other run of the wire will try to move downwards, as described above.

Fig. 3 shows a variant, where each deflection wheel 8, 9 is connected with a gear wheel 17, 18 in engagement with a rack 19, 20 of its own, whose free end is connected with the outermost profile 1 and the innermost profile 3, respectively. When the innermost section 1 is extended, the rack 19 se¬ cured thereto will cause the deflection wheel 8, the wire 10 and thereby the lowermost deflection wheel 9, the gear wheel 18 to move and thereby syn¬ chronously extend the intermediate section 2, as the rack 20 presses on the bottom of the outermost member 3.

Fig. 4 shows a variant, in which a train 21 of gear wheels is provided in¬ stead of a wire and deflection wheels. The last gear wheels 22, 23 in the train are in engagement with the respective racks 19, 20 directly or via a separate gear wheel connected with the last gear wheel.

Another embodiment based on a single gear wheel 24 and two racks 25, 26 is shown in fig. 5. The lower end of the intermediate section 2 has secured thereto a rod 27 having a head 27a with an opening in which the gear wheel 24 is mounted. The gear wheel extends with the teeth outside the rod. The racks 25, 26 extend through the opening on each side of the gear wheel 24, i.e. the racks are guided in the opening and are moved along the rod. The structure is expediently made entirely of plastics.

A further embodiment with racks is shown in fig. 6, in which a rack 28 is secured on the inner side of the outermost section 1. This rack 28 extends at least over the lower half of the section, and is here provided with teeth on both longitudinal narrow sides. Two racks 29, 30 are secured to the outer side of the innermost section 3 on each side of this rack 28, said racks 29, 30 extending at least over the upper half of the length of the innermost sec¬ tion. Two pairs of gear wheels 31, 32 are provided in the intermediate sec- tion 2. The gear wheels of each pair are fitted on the inner side and the outer side, respectively, of the section 2 and are in engagement with the respective racks 29, 30 on the innermost section 3 and the rack 28 on the outermost section 1. When the innermost section 1 is extended, the inter- mediate profile 2 will run partly along the rack 28 on the outermost profile and partly along the racks 29, 30 on the innermost profile. With sections of a circular cross-section, the mechanism will also serve as a rotation protec¬ tion, i.e. protection against mutual rotation of the sections 1, 2, 3 about their axial axes. The sections 1 , 2, 3 are simply mutually locked by the racks 28, 29, 30 in engagement with the gear wheels 31, 32.

Still another embodiment based on spindles is shown in fig. 7 of the draw¬ ing. The two spindles 33, 34 are connected with each other via a gear transmission arranged in the intermediate section. The one spindle 34 is connected with the outermost section 1, and the other spindle 33 is in en¬ gagement with a spindle nut 35 secured to the innermost section 1. The column is shown upside down here, e.g. with the outermost section 1 at the top and the innermost section 3 at the bottom. When the outermost section 1 is extended, the spindle 34 connected with the top of the outermost sec- tion via the gear transmission 36 will cause the other spindle 33 to rotate. It will then screw itself up the spindle nut 35 secured in the innermost section 3, whereby the intermediate section 2 will be lifted. The gear transmission 36 comprises a toothed rim 37 in engagement with a gear wheel 38 on the end of the spindle 33 as well as the spindle nut 39, which is externally con- figured as a gear wheel. The parts are arranged in a housing consisting of two halves 40, 41.

A further embodiment with a spindle is shown in fig. 8. Here, a solid spindle

44 is connected via a gear transmission 45 with the transmission for a solid spindle 46 in the lifting device for the column. The solid spindle in the lifting device is in engagement with a hollow spindle 47, which is in turn in en- gagement with a nut in a carrier pipe 48 mounted in the outermost member 1. The whole is driven by a motor 49. The solid spindle 44 for moving the intermediate section 2 is in engagement with a spindle nut in the upper end of a carrier pipe 50 mounted in the intermediate section 2. It will be appre- dated that the solid spindle 44 with associated carrier pipe 50 and nut for moving the intermediate section 2 may be made very slender, since they are not to carry the load, but exclusively move the intermediate section. For that matter, the nut might merely be carried by a rod rather than a pipe. The spindle part, i.e. the spindle 44, the spindle nut, the carrier pipe 50 and the gear wheel might be made of plastics, for that matter.

Another embodiment based on specially configured rollers 51 in the gap between the individual sections is shown in fig. 9 of the drawing. The rollers have an appearance like "dumbbells" with a large portion 52 at each end and an intermediate portion 53 of half the diameter. The roller is of a friction material, e.g. with a rubber surface. The two large portions 52 are in en¬ gagement with the outer side of the one section 1 , 2, while the intermediate portion 53 is in engagement with a strip 54 on the inner side of the subse¬ quent section 2, 3. When the innermost section 3 is moved, the rollers 51 will cause a synchronous movement of the innermost section 2. The struc¬ ture has the additional advantage that it serves as a rotation protection in columns of a circular cross-section. The strip 54 disposed between the two large portions 52 on the roller 51 prevents the sections 1, 2, 3 from rotating mutually.

Still another embodiment based on a wire, a cord, a tape, a belt or the like is shown in fig. 10 of the drawing. The wire 55 is secured with its one end at the upper end of the innermost section 3 and, over a deflection roller 56 at the lower edge of the intermediate section 2, is passed up for attachment at the upper edge of the outermost section 1. When the innermost section 3 is extended, the intermediate section 2 will be raised, too, by the pull in the wire 55. It is observed for the sake of good order that it is only the one side wall of the sections which is shown in the two sketches to the right in fig.10. For pulling the intermediate section 2 in the return direction, an additional wire 57 is secured at the lower edge of the innermost section 3 and, over a deflection roller 58 at the upper edge of the intermediate section 2, is passed down for attachment at the lower edge of the outermost section 1. The deflection rollers need not necessarily be wheels, but may be semicir¬ cular guides. A particularly simple guide, which also prevents the wire from dropping off, is formed by a pipe bend, e.g. just a length of hose 58 which is bent.

A further embodiment based on fixing the intermediate section 2 between two sets of springs 59, 60 is shown in fig. 11. The one spring 60 is secured with its one end at the lower edge of the innermost section 3 and with the other end at the upper edge of the intermediate section 2, while the other spring 59 is secured with its one end at the lower edge of the intermediate section 2 and with the other end to the upper edge of the outermost section 3. It will be appreciated that the springs may be screw springs which sur¬ round the sections 2, 3, but it may also be resilient bands placed at one or more locations on the circumference of the sections. It is observed for the sake of good order that it is only the one side wall of the sections which is shown in the sketch.

Another way of performing the synchronization is by means of threads be- tween the individual sections 1, 2, 3. This, however, has the effect that the intermediate section will rotate during its axial movement. Fig. 12 shows a particularly simple embodiment with threads in the form of a strip 61, 62 secured internally in the outermost and the intermediate sections 1, 2. A key, e.g. just in the form of two bosses, is mounted on the innermost sec- tion 3 and the intermediate section 2 in engagement with the respective strips 61, 62. When the innermost section 3 is moved, the intermediate section 2 will move synchronously therewith during a rotation.

It will be appreciated that the invention may be realized in other ways than those outlined in the drawing.

Still another way of providing the synchronization is with a pulley in connec¬ tion with the intermediate section, and where two separate wires are con¬ nected with the inner section and the outer section, respectively. The wires are wound around the pulley in the same direction, so that they both slacken or tauten at the same time. The pulley may be provided with a spring device which automatically coil up the wires and keep them taut. An advantage of the solution is inter alia that it is useful at all lengths of stroke merely by mounting the wires with the same tightness. In a variant of the solution, the pulley is secured in the inner section rather than the intermedi- ate one. The pulley has two diameters, viz. a length of a diameter half as large as the other length, where the wire to the intermediate section is wound around the first length, viz. the length of half diameter, and the wire to the outermost section around the second length.

Instead of wire, use may be made of a steel strip, which is more rigid than a wire. This results in a more precise synchronization. To prevent the steel strip from deflecting, it may be retained in a guide. In a further development, the pulley is secured with two steel strips in the intermediate section. The one steel strip is secured in the innermost section, and the other is pulled through two pulleys on the outermost section and is pulled back, and the end is secured to the intermediate section. When the column is extended, the distribution of the steel strips is one to two, i.e. the innermost and inter¬ mediate sections are extended in synchronism.

A further solution for synchronized control of the intermediate section is based on connected cylinders, where a fluid, preferably liquid, is moved from one cylinder to the other. The intermediate section is moved half the travel of the innermost section by using half the diameter of the cylinder secured to the intermediate section.

Claims

PATENT CLAIMS

1. A lifting column comprising a guide having an outermost section and an innermost section (1, 3) as well as at least one intermediate section (2), said sections being arranged to be mutually telescopic, with slides arranged between the sections, as well as a drive device (46-49) for causing the tele¬ scopic movement, characterized in that it comprises independent means for synchronized control of the at least one intermediate section relative to the outermost and innermost sections.

2. A lifting column according to claim ^ characterized in that the means for synchronization are formed by a chassis with an endless ele¬ ment, such as a band, a belt, a cord, a wire, a chain passed around a de¬ flection wheel at each end of the chassis, and wherein a rod is connected with the two runs between the wheels with its one end, and wherein the other end of the rod is connected with the top of the innermost section and with the bottom of the outermost section, respectively, and wherein the chassis is connected with the central section.

3. A lifting column according to claim ^characterized in that the means for synchronization are formed by a chassis (7) with an element, such as a band, a belt, a cord, a wire, a chain (10) passed around a deflec¬ tion wheel (8, 9) at each end of the chassis, and wherein a rod (13) is con¬ nected with one run between the wheels with its one end, and wherein the other end of the rod is connected with the bottom of the outermost section (3), and wherein the one end of the element (10) is connected with the top of the innermost section (3), and wherein the other end is connected with a run between the two wheels (8, 9) (fig.2).

4. A lifting column according to claim 1, characterized in that the means for synchronization are formed by a chassis with an element, such as a band, a belt, a cord, a wire, a chain (10) passed around a deflection wheel (8, 9) at each end of the chassis, and wherein each deflection wheel is connected with a gear wheel (17, 18) in engagement with a rack (19, 20) whose free ends are connected with the outermost section (1) and the in- nermost section (3), respectively, and wherein the chassis is connected with the intermediate section (2) (fig.3).

5. A lifting column according to claim ^characterized in that the means for synchronization are formed by a chassis with a train of gear wheels (21), wherein each last gear wheel (22, 23) in the train is in en¬ gagement with a rack (19, 20) directly or via a separate gear wheel con¬ nected with the last gear wheel, the free ends of said rack being connected with the outermost section (1) and the innermost section (3), respectively, and wherein the chassis is connected with the intermediate section (2) (fig. 4).

6. A lifting column according to claim ^ characterized in that the means for synchronization are formed by a chassis secured to the interme¬ diate section (2) and carrying a gear wheel (24) in connection with two racks (25, 26), wherein the one rack (25) is connected with the top of the innermost section (3) with its end, and wherein the other rack (26) is con¬ nected with the bottom of the outermost section (1) with its one end (fig.5).

7. A lifting column according to claim 1, characterized in that the means for the chassis are configured as a rod (27) having a head (27a) for the gear wheel (24), and in connection with the gear wheel an opening for each rack (25, 26) as a guide for these.

8. A lifting column according to claim 1, characterized in that a rack (28) is secured on the inner side of the outermost section (3), and that at least one rack (29, 30) is secured on the outer side of the innermost profile (3), and that at least one pair of gear wheels (31, 32) is secured in the in¬ termediate profile (2), wherein the one gear wheel of said pair is in en¬ gagement with the rack (28) on the outermost section, and the other is in engagement with the rack (29, 30) on the innermost section (fig.6).

9. A lifting column according to claim 1, characterized in that the means for synchronization comprise two spindles (33, 34) which are con¬ nected with each other via a gear transmission (36) mounted in the inter¬ mediate section (2), and wherein the one spindle (34) is connected with the outermost section (1), and wherein the other spindle (33) is in engagement with a spindle nut (35) secured to the innermost section (3) (fig.7).

10. A lifting column according to claim 1, characterized in that the means for synchronized control of the intermediate section comprise a solid spindle (44) driven by the electric motor (49) via a gear transmission (45), said solid spindle cooperating with a nut secured to the intermediate section

(2) (fig.8).

11. A lifting column according to claim 1, characterized in that the means for synchronized control of the intermediate section comprise rollers

(51) disposed between two adjacent sections, said rollers having partly a portion (52) of a given diameter in engagement with the one section (2,3) and partly another portion (53) of half-diameter in engagement with a strip (54) on the subsequent section (1, 2) (fig.9).

12. A lifting column according to claim ^characterized in that the means for synchronized control of the intermediate section comprise a wire (56) or the like, which is secured at the upper end of an innermost section

(3) with its one end and, over a deflection roller (56) at the lower edge of the intermediate section (2), is passed up for attachment at the upper edge of the outermost section (1) (fig.10).

13. A lifting column according to claim ^ cha racterized in that it additionally comprises a wire (57) secured at the lower edge of the inner¬ most section (3) and, over a deflection roller (58) at the upper edge of the intermediate section (2), is passed down for attachment at the lower edge of the outermost section (1 ).

14. A lifting column according to claim ^characterized in that the means for synchronized control of the intermediate section comprise a spring (60) secured at the lower edge of the innermost section (3) with its one end and at the lower edge of the intermediate section (2) with the other end, and wherein another spring (59) is secured at the lower edge of the intermediate section (2) with its one end, and wherein the other end is se¬ cured at the upper edge of the outermost section (1) (fig.11).

15. A lifting column according to claim ^characterized in that the means for synchronized control of the intermediate section comprise threads or a threaded member between the sections (fig.12).

16. A lifting column according to claim ^characterized in that the means for synchronized control of the intermediate section comprise a pul¬ ley in connection with the intermediate section with two separate wires, cords, tapes, belts or the like connected with the inner section and the outer section, respectively.

17. A lifting column according to claim 16, characterized in that a steel strip, preferably secured in a guide, is used.

18. A lifting column according to claim ^characterized in that the means for synchronized control of the intermediate section comprise con- nected cylinders, wherein a fluid is displaced from the one to the other by the extension of the innermost section, whereby the intermediate section is extended synchronously.