FURNITURE SYSTEM HAVING A LINEAR ACTUATOR

Abstract

A furniture system having a furniture item which includes an electrically-adjustable component, a control unit and a linear actuator for adjusting a component of the furniture item is provided. The linear actuator includes a gear mechanism including a hollow element and a first stage formed as a friction wheel stage. The linear actuator further includes a motor on a drive side and an adjustment member arranged on an output side. The linear actuator, in particular the motor, the gear mechanism and the adjustment member are adapted to alter a length of the adjustment member by means of the motor and the gear mechanism. The control unit is coupled with the linear actuator and adapted to actuate the linear actuator for adjusting the component.

Claims

1. A furniture system with a furniture item including an electrically-adjustable component, a control unit and a linear actuator for adjusting a component of the furniture item, the linear actuator including a gear mechanism which includes a hollow element and a first stage configured as a friction wheel stage; a motor arranged on the drive side; and an adjustment member arranged on the output side; wherein the linear actuator is adapted to alter a length of the adjustment member through the motor and the gear mechanism; and wherein the control unit is coupled with the linear actuator and adapted to actuate the linear actuator for adjusting the component.

2. The furniture system according to claim 1, wherein the gear mechanism is formed as a coaxial gear mechanism.

3. The furniture system according to claim 1, wherein the first stage is formed as a planetary stage having at least one central element as well as at least two planetary elements.

4. The furniture system according to claim 3, wherein the planetary elements in the first stage are arranged between an inner surface of the hollow element and an outer surface of the central element; and the planetary elements are connected to the hollow element and the central element in a force-fit manner.

5. The furniture system according to claim 4, wherein the planetary elements, the central element as well as the hollow element are of cylindrical shape.

6. The furniture system according to claim 4, wherein the planetary elements have an oversize; normal forces between the inner surface of the hollow element and the planetary elements as well as between the outer surface of the central element and the planetary elements are generated by the oversize; and the force-fit connections of the planetary elements with the hollow element and the central element result from the normal forces.

7. The furniture system according to claim 4, wherein the linear actuator also includes a support element arranged on an output side and having the planetary elements mounted thereon.

8. The furniture system according to claim 7, wherein each of the planetary elements includes in each case one sleeve, in particular a cylindrical sleeve, which is mounted on the carrier element in a rotationally-movable manner and which includes a friction pad connected to the surface of the sleeve.

9. The furniture system according to claim 8, wherein the friction pad includes an elastomer plastic material, an elastomer polyurethane and/or a composite plastic material.

10. The furniture system according to claim 1, wherein the gear mechanism includes a second stage which is formed as a toothed gear stage.

11. The furniture system according to claim 1, wherein the adjustment member includes a telescopic spindle, a threaded spindle or another spindle.

12. The furniture system according to claim 1, wherein the linear actuator also includes a position sensor which is adapted to determine a position of the gear mechanism.

13. The furniture system according to claim 12, wherein the position sensor is adapted to generate a position signal for determining a position of the adjustment member.

14. The furniture system according to claim 13, further including at least one further linear actuator which is adapted and arranged on the furniture item to adjust the component, wherein the further linear actuator includes a further gear mechanism, a further adjustment member and a further position sensor; the further position sensor is adapted to determine a position of the further gear mechanism and to generate a further position signal for determining a position of the further adjustment member based on the determined position of the further gear mechanism; and the control unit is adapted to actuate the further linear actuator for adjusting the component of the furniture item; determine the positions of the adjustment member and of the further adjustment member depending on the position signal and the further position signal; and synchronize the positions of the adjustment member and the further adjustment member by actuating the linear actuator and the further linear actuator.

15. The furniture system according to claim 14, wherein the further linear actuator includes a further motor arranged on a drive side; the further gear mechanism includes a further hollow element and a further first stage formed as a friction wheel stage; the further linear actuator is adapted to alter a length of the further adjustment member through the further motor and the further gear mechanism.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0047] The Figures show in:

[0048] FIG. 1 an example embodiment of a linear actuator according to the improved concept;

[0049] FIG. 2 a part of another example embodiment of a linear actuator according to the improved concept;

[0050] FIG. 3A a cross-section through a first stage of a gear mechanism of a linear actuator according to the improved concept;

[0051] FIG. 3B a cross-section through a second stage of a gear mechanism of a linear actuator according to the improved concept;

[0052] FIG. 4B a detailed view of a gear mechanism in an example embodiment of the linear actuator according to the improved concept;

[0053] FIG. 4B another detailed view of a gear mechanism in an example embodiment of the linear actuator according to the improved concept; and

[0054] FIG. 5 an example embodiment of a furniture system having linear actuators according to the improved concept.

DETAILED DESCRIPTION

[0055] FIG. 1 shows an example of an embodiment of a linear actuator according to the improved concept. The upper part of FIG. 1 shows a side view of the linear actuator, whereas the lower part of FIG. 1 shows a perspective view of this linear actuator.

[0056] The linear actuator includes a gear mechanism G, a motor M, which is coupled to the gear mechanism G on the drive side, as well as an adjustment member V connected to the gear mechanism G on the output side. The linear actuator further comprises a first fastening element B1 fixed to the motor M and a second fastening member B2 fixed to the adjustment member V.

[0057] The adjustment member V includes a telescopic spindle. Exemplary embodiments of the adjustment member V are shown in documents DE 10 2012 102 298 A1 as well as DE 10 2012 013 979 A1, the disclosures of which are incorporated in their entirety into the present document by reference.

[0058] In the illustrated embodiment of the linear actuator, the gear mechanism G includes a hollow element H, which is formed by a housing of gear mechanism G. The gear mechanism G is formed as a coaxial gear mechanism and includes a first stage G1 (not shown in FIG. 1, see FIGS. 3A, 4A and 4B), which is formed as a friction gear stage.

[0059] The linear actuator for adjusting a component of a furniture item, e.g. a table, can be fastened to the furniture item and/or the component by means of the fastening elements B1, B2.

[0060] The motor M produces a rotational movement during operation, the rotational movement being transmitted from the gear mechanism G to the adjustment member V and translated from the adjustment member V into a linear movement, in particular a length adjustment of the adjustment member V.

[0061] The motor M is formed as an electric motor, preferably a DC motor, a brushless DC motor, for example. An operating point of the motor M may include a drive-sided rotational speed in the range of several thousand revolutions per minute, e.g. about 5,000 min.sup.−1, and a drive-sided torque in the range of several tenths of Nm, for example about 0.1 Nm to 0.2 Nm. Depending on the application, other operating points are of course also possible.

[0062] An output-side rotational speed of the gear mechanism G can range from several hundred to a few thousand revolutions per minute, for example in a range from 700 to 1,000 min.sup.−1. Compared to the values for the drive-side rotational speed mentioned above, this corresponds to a transmission ratio of about 5 to 7. A corresponding output-side torque may be in the range of 1 Nm, e.g. 0.7 to 1 Nm, for example. In this case as well, the characteristic values may take other values depending on the application.

[0063] FIG. 2 shows part of another exemplary embodiment of a linear actuator according to the improved concept. The linear actuator corresponds to the linear actuator shown in FIG. 1, for example. For the sake of clarity, part of the linear actuator, in particular the fastening elements B1, B2, parts of the motor M as well as of the adjustment member V are not shown in FIG. 2.

[0064] The gear mechanism G includes the hollow element H, which is formed by the housing G. In the embodiment shown, the hollow element H is made of a plastic material, polyoxymethylene for example.

[0065] The gear mechanism G is connected with a shaft W (only shown in part here) on the drive side. In one embodiment of the linear actuator, the shaft W is connected to the motor M. Furthermore, part of the adjustment member V or of the telescopic spindle is shown, which is connected to the gear mechanism G on the output side.

[0066] FIG. 3A shows a cross-section through a first stage G1 of a gear mechanism G of a linear actuator according to the improved concept. The linear actuator corresponds to the linear actuator shown in FIGS. 1 and 2, for example.

[0067] The first stage G1 is configured as a coaxial friction wheel stage and planetary stage. The first stage G1 includes a cylindrical central element Z coupled to the shaft W. The first stage further includes a first cylindrical planetary element P1, a second cylindrical element P2 as well as a third cylindrical planetary element P3. The planetary elements P1, P2, P3 are arranged rotationally-symmetrical around the central element Z and connected to an inner surface of the hollow element H and an outer surface of the central element Z. Alternatively, the planetary elements P1, P2 and P3 may also be arranged asymmetrically. In the embodiment shown, the central element Z is made from steel, for example.

[0068] The planetary elements P1, P2, P3 of the first stage G1 are configured as frictional planets. The frictional planetary elements P1, P2, P3 include a first friction pad 1, a second friction pad R2 or a third friction pad R3, respectively, as well as a first sleeve HLS1, a second sleeve HLS2, and a third sleeve HLS3, respectively. In the embodiment shown, sleeves HLS1, HLS2, HLS3 each comprise an outer sleeve HA1, HA2, HA3 as well as an inner sleeve HI1, HI2, HI3. Inner sleeves HI1, HI2, HI3 each include four rollers WZ in the embodiment shown. The sleeves HLS1, HLS2 and HLS3 are mounted to a carrier element T1 in a rotationally-movable manner. Here, rotational movability is given by a rotationally-movable arrangement of rollers WZ in the inner sleeves HI1, HI2, HI3.

[0069] In alternative embodiments, the planetary elements P1, P2, P3 include one-piece sleeves instead of the two-piece configuration, shown here, of the sleeves HLS1, HLS2, HLS3 having outer sleeves HA1, HA2, HA3 and inner sleeves HI1, HI2, HI3. In particular, the sleeves do not include rollers WZ in such embodiments. In such embodiments, sleeves HLS1, HLS2, HLS3 directly rest on the carrier element T1 in a rotationally-movable manner.

[0070] In the embodiment shown, inner sleeves HI1, HI2, HI3, outer sleeves HA1, HA2, HA3 and rollers WZ are made of a metal, e.g. brass, or of a plastic material, for example. Friction pads R1, R2, R3 are made e.g. of an elastomeric plastic in the embodiment shown. The first friction pad R1 is glued to or cast with the first sleeves HLS1, the second friction pad is glued to or cast with the second sleeve HLS2, and the third friction pad is glued to or cast with the third sleeve HLS3. A cyano-acrylate glue can be used for gluing, for example. The first stage G1 is connected to the motor M via the shaft W.

[0071] The force-fit connections of the planetary elements P1, P2 P3 with the inner surface of the hollow element H and the outer surface of the central element Z preferably result from oversizes of the planetary elements P1, P2, P3, in particular radial oversizes with respect to a distance between the inner surface of the hollow element and the outer surface of the central element. This produces normal forces between the inner surfaces of the hollow element and the planetary elements as well as between the outer surface of the central element and the planetary elements and thus the force-fit connections. The normal forces per planetary element can be in the range of several ten Nm, e.g. about 60-70 Nm, for example.

[0072] In alternative embodiments of the linear actuator, the number of the planetary elements P1, P2, P3 may be other than three. In particular, the first stage G1 may include only 2, but also four, five or more planetary elements.

[0073] FIG. 3B shows a cross-section through a second stage G2 of a gear mechanism G of a linear actuator according to the improved concept. The gear mechanism G and the linear actuator correspond to the ones shown in FIG. 3A, respectively.

[0074] The second stage G2 is configured as a coaxial toothed gear stage and planetary stage. The second stage G2 includes further planetary elements P4, P5, P6, i.e. a fourth planet element P4, a fifth planet element P5 as well as a sixth planetary element P6. The further planetary elements P4, P5, P6 are configured as toothed gear planets. Accordingly, the hollow element H is equipped with internal teeth in the area of the second stage G2, which are engaged by the teeth of the further planetary elements P4, P5, P6.

[0075] The further planetary elements P4, P5 P6 are mounted on a further carrier element T2 in a rotationally-movable manner. Alternatively, the further planetary elements P4, P5 P6 can also be fixedly connected with components of the further carrier element T2. The components are then per se supported in a rotationally-movable manner. The further carrier element T2 is connected to the adjustment member V via a second shaft, for example. The further carrier element T2 can be supported on a bearing, e.g. a roller bearing, for example. The carrier element Ti is equipped with externally-located teeth on the side of the second stage G2, which teeth are engaged by the teeth of the further planetary elements P4, P5, P6. With respect to the second stage G2, the carrier element T1 serves as a further central element for the further planetary elements P4, P5, P6. The further planetary elements P4, P5, P6 are arranged around a center of the first carrier element T1 in a rotationally-symmetrical manner, but may alternatively also be arranged asymmetrically.

[0076] In alternative embodiments, the number of the further planetary elements P4, P5, P6 may be other than three. In particular, the second stage G2 may only include two, but as well four, five or more planetary elements.

[0077] In alternative embodiments, the second stage G2 may as well be configured as a friction wheel stage analogously to the first stage G1 shown in FIG. 3A.

[0078] In various embodiments, the linear actuator includes a position sensor configured as a Hall sensor, for example. In embodiments based on the one shown in FIGS. 3A and 3B, the position sensor is adapted to determine a position, e.g. of a further carrier element, for example. The position of the further carrier element T2 may include a rotational position and/or a number of revolutions of the further carrier element T2, for example.

[0079] FIGS. 4A and 4B show a perspective detailed view of the gear mechanism G shown in FIGS. 3A and 3B. Here, a longitudinal section through the gear mechanism G is shown. The following explanations refer to both FIG. 4A and FIG. 4B.

[0080] The gear mechanism G includes a first stage G1 and a second stage G1 according to the embodiments shown in FIGS. 3A and 3B. In alternative embodiments, the second stage G2 may also be formed as a friction wheel stage analogously to the first stage G1 shown in FIG. 3A.

[0081] The first and second stages G1, G2 are connected to one another via the carrier element T1. A rotational movement of the shaft W is generated via the motor M. This rotational movement is translated into a rotational movement of the central element Z. The rotational movement of the central element Z is translated into a rotational movement of the planetary elements P1, P2, P3 about themselves and into a rotational movement of planetary elements P1, P2, P3 about the central element Z due to the force-fit connections between the central element Z and the planetary elements P1, P2 and P3 and the hollow element H. This also causes a rotational movement of the carrier element T1.

[0082] Due to the meshing between the teeth of the further planetary elements P4, P5, P6 and the teeth of the carrier element T1 located on the outside with respect to the second stage G2 and the teeth of the hollow element H located on the inside, the rotational movement of the carrier element T1 is translated into a rotational movement of the further planetary elements P4, P5, P6 about themselves as well as into a rotational movement of the further planetary elements P4, P5, P6 about the further central element. This results in a rotational movement of the further carrier element T2, which is transmitted to the adjustment member V via the second shaft, in particular to the telescopic spindle, for example. Finally, the adjustment member V translates the rotational movement into a linear movement, in particular into a length alteration of the adjustment member V.

[0083] The structure of the gear mechanism in a linear actuator according to the improved concept can be formed in one or multiple stages. In a multistage gear mechanism G, the first stage G1 of gear mechanism G is configured as a friction wheel stage, whereas at least one of the second stage G2 and the further stages can be formed in a conventional construction, since the dominant noise source is the first stage G1 with the first speed ratio, for example.

[0084] Various embodiments of the linear actuator corresponding to the improved concept comprise a gear mechanism G having an improved noise quality when compared to a worm gear, for example. Furthermore, embodiments of the linear actuator which have a coaxial gear structure allow high flexibility when using the linear actuator.

[0085] Further advantages of the linear actuator according to the improved concept may include low construction effort, low maintenance effort, a direction reversal without clearance and less effort in lubricating the gear mechanism G or a potential dispense with lubrication.

[0086] FIG. 5 shows an exemplary embodiment of a furniture system having linear actuators according to the improved concept. In the present example, the furniture system includes a table with a table top, a first table leg TB1 and a second table leg TB2, for example. Table legs TB1, TB2 have a first drive A1 or a second drive A2 mounted thereon. The furniture system further includes a control unit STR, which is fixed to the tabletop TP and connected to the drives A1, A2, for example.

[0087] The first and second drives A1, A2 each include a linear actuator according to the improved concept. The control unit STR is adapted to actuate the linear actuators. The linear actuators are adapted to adjust a height of the tabletop TP depending on the actuation by the control unit STR.

[0088] The linear actuators each comprise a position sensor as described with reference to FIG. 3A, for example. The control unit STR is coupled to the position sensors and adapted to determine positions of the adjustment members V of the linear actuators depending on the position signals. The control unit STR is also adapted to synchronize the linear actuators, in particular the positions of the adjustment members V, by actuating the linear actuators. Synchronization of the linear actuators allows achieving an optimized adjustment of the table top TP, for example.