SPINDLE SYSTEM, LINEAR ACTUATOR AND FURNITURE ITEM

Abstract

A spindle system with a hollow spindle for a linear actuator, wherein - the linear actuator comprises a telescopic tube system surrounding the spindle system, wherein the telescopic tube system comprises an outer tube and at least one inner tube arranged coaxially to the outer tube and at least partially surrounded by the outer tube; - a bearing for transmitting axial forces, in particular for transmitting thrust or tensile forces, is arranged between the hollow spindle and the outer tube; and - a rotational movement of the spindle system does not cause a rotational movement of the outer tube; the hollow spindle - at least partially surrounds an internal shaft of the spindle system; - is connected to the internal shaft of the spindle system by a positive and axially movable shaft-hub connection; - has an external thread on one outer side; and - has a bearing seat for the bearing; and wherein - the shaft-hub connection is formed by a profiling of the inner shaft and a profiling of the inside of the hollow spindle; - the profiling of the inner shaft and the profiling of the inside of the hollow spindle are each created by one or more drivers which form the shaft-hub connection; - the one or more drivers of the profiling of the inner shaft are formed by drivers on a sliding element which is connected in a rotationally fixed manner to the inner shaft; - the sliding element has one or more elastic compensating elements which fit snugly against the drivers of the hollow spindle in order to minimize the radial play between the one or more drivers of the sliding element and the one or more drivers of the hollow spindle over the entire length of the hollow spindle; and - the external thread of the hollow spindle, the one or more drivers of the hollow spindle and the bearing seat are made from a single casting and consist of the same plastic.

Description

[0001] The present invention relates to a spindle system with a hollow spindle for a linear actuator, in particular for a telescopic lifting column of a height-adjustable furniture leg. Furthermore, the present disclosure relates to a linear actuator with such a spindle system and a piece of furniture with such a linear actuator.

[0002] Telescopic lifting columns are used, for example, as height-adjustable table legs and feature a linear actuator with a multi-stage spindle drive with several, particularly two, spindles. The spindle drive is typically surrounded by several nestable tubular profiles, which can be moved relative to each other along their longitudinal axes by the spindle drive.

[0003] Examples of such linear actuators can be found in DE 202 14 566 U1 or DE 10 2010 000 970 A1.

[0004] A linear actuator within the meaning of the present disclosure comprises at least one drive, preferably electric, and a telescopic tube system surrounding a spindle system. The telescopic tube system has an outer tube and at least one inner tube arranged coaxially with the outer tube and at least partially surrounded by the outer tube. Optionally, the linear actuator can also have a gear, in particular a planetary gear, and / or a brake.

[0005] In such a linear actuator, a rotary movement of the spindle system, for example, does not cause a rotary movement of the outer tube. The rotary movement of the spindle system, for example, causes a translational movement of the outer tube in the axial direction.

[0006] For example, such a telescopic pipe system with a spindle system can have the following structure: An internal shaft is connected to the drive. The internal shaft is located within a hollow spindle.

[0007] In one embodiment, the internal shaft can be, for example, a drive spindle on which a drive spindle nut is mounted. In this embodiment, the drive spindle nut has a holder for an outer tube. Additionally, a hollow spindle is attached to the drive spindle nut via a bearing, in particular a ball or plain bearing, which serves to transmit axial forces, in particular thrust or tensile forces, between the hollow spindle and the outer tube. The hollow spindle has a bearing seat for the bearing.

[0008] The hollow spindle is connected to the inner shaft of the spindle system by one or more axially movable drivers and has a hollow spindle nut. The hollow spindle nut has a holder for the inner and outer tubes. The holder is connected to the inner and outer tubes in a rotationally fixed manner.

[0009] The hollow spindles used in common spindle systems are typically metal hollow spindles, such as aluminum, especially rolled aluminum. Such spindles are expensive and heavier than, for example, plastic.

[0010] Against this background, one task is to provide an improved spindle concept that reduces deficiencies in conventional spindle systems.

[0011] This problem is solved by the subject matter of the independent claims. Further developments are identified in the dependent claims.

[0012] A linear actuator within the meaning of the present disclosure comprises at least one drive, preferably electric, and a telescopic tube system surrounding an internal spindle system. The telescopic tube system has an outer tube and at least one inner tube arranged coaxially with the outer tube and at least partially surrounded by the outer tube. Optionally, the linear actuator can also have a gear, in particular a planetary gear, and / or a brake.

[0013] In such a linear actuator, a rotary movement of the spindle system, for example, does not cause a rotary movement of the outer tube. The rotary movement of the spindle system, for example, causes a translational movement of the outer tube in the axial direction.

[0014] A bearing is designed to transmit axial forces, in particular to transmit thrust or tensile forces, between a hollow spindle and the outer tube.

[0015] The improved spindle concept is based on the realization that advances in plastics now allow the required strength of the hollow spindle to be achieved while maintaining a small diameter, even with a plastic design. Accordingly, the hollow spindle is manufactured from plastic, specifically using a casting process.

[0016] In one embodiment of a spindle system with a hollow spindle for a linear actuator according to the improved spindle concept, the hollow spindle at least partially surrounds an internal shaft of the spindle system. The hollow spindle is also connected to the internal shaft of the spindle system by one or more drivers of a positive and axially displaceable shaft-hub connection, which is located in particular on an inner side of the hollow spindle. The hollow spindle has a bearing seat for the bearing and an external thread on an outer side. The external thread of the hollow spindle, the one or more drivers of the hollow spindle, and the bearing seat are made from a single casting and consist of the same plastic or are manufactured from the same plastic.

[0017] By using plastic for the hollow spindle, the weight of the spindle system can be kept low. Furthermore, such a spindle system, as well as a linear actuator with such a spindle system, can be manufactured more cost-effectively.

[0018] According to the invention, the shaft-hub connection is formed by profiling the inner shaft and profiling the inner surface of the hollow spindle. The profiling of the inner shaft and the profiling of the inner surface of the hollow spindle are each created by one or more drivers. For example, the drivers are each designed in the form of ribs, wedges, teeth, or non-circular profiles, which can engage with each other to create a positive connection.

[0019] The shaft-hub connection thus comprises one or more drivers, e.g., ribs, on the inside of the hollow spindle and a sliding element that is non-rotatably connected to the internal shaft and also comprises one or more drivers. The one or more drivers of the sliding element transmit the torque to the hollow spindle via the one or more drivers of the hollow spindle.

[0020] The sliding element has one or more elastic compensating elements that fit snugly against the drivers of the hollow spindle to minimize the radial play between the one or more drivers of the sliding element and the one or more drivers of the hollow spindle along the entire length of the hollow spindle. This results in better power transmission and lower noise. For example, each of the one or more elastic compensating elements fits snugly against the flanks of the drivers of the hollow spindle.

[0021] For example, each of the drivers of the profile on the inside of the hollow spindle has two flanks, the distance between which varies in the axial direction of the hollow spindle. By varying the distance, such as a taper starting at one end of the hollow spindle, the tool can be more easily removed from the inside of the hollow spindle in an injection molding process once the casting process is complete.

[0022] The hollow spindle has a first and a second end in the axial direction. For example, each of the drivers of the profile of the inner side of the hollow spindle has two flanks, the distance between which is smaller between the first and second ends, particularly in the center of the hollow spindle, than at the first and second ends of the hollow spindle.

[0023] In other designs, the distance between the two flanks decreases continuously, starting from the first end to the second end or vice versa.

[0024] In different designs, an inner diameter of the hollow spindle varies between opposite drivers of the profiling of the inner side of the hollow spindle in the axial direction of the hollow spindle.

[0025] For example, the inner diameter between opposite drivers of the profiling of the inner side of the hollow spindle between the first and the second end, in particular in the middle of the hollow spindle, is smaller than at the first and the second end of the hollow spindle.

[0026] In other designs, the inner diameter decreases continuously, from the first end to the second end, or vice versa. Preferably, the inner diameter changes in line with the pitch of the flanks.

[0027] In various designs, the one or more drivers of the profiling of the inner shaft are formed by drivers on a sliding element that is connected in a rotationally fixed manner to the inner shaft, for example by pressing onto the shaft.

[0028] Each of the one or more elastic compensating elements may comprise one or more, for example, two, legs that are spaced apart from one another and are elastic. Alternatively, each of the one or more elastic compensating elements may comprise an elastic, self-contained, for example, annular or elliptical, part.

[0029] In various embodiments, the bearing seat of the hollow spindle has an axial stop on both sides relative to the inner ring of a rolling bearing or a plain bearing, in particular a disk-shaped plain bearing, with the bearing being formed by the rolling bearing or the plain bearing. For example, there is a material connection between at least part of the bearing and the axial stop on both sides of the bearing seat of the hollow spindle.

[0030] For example, an inner ring of a rolling bearing is at least partially overmolded with the plastic of the hollow spindle. Alternatively, an inner ring of a rolling bearing, such as a plastic inner ring, is fused to the bearing seat. In a bearing design as a plain bearing, for example, the plain bearing is at least partially overmolded with the plastic of the hollow spindle.

[0031] In various embodiments, the external thread of the hollow spindle is interrupted in two circumferential regions of the hollow spindle, which extend over the entire axial length of the external thread and are arranged diametrically opposite each other with respect to the hollow spindle axis. By interrupting the thread profile of the hollow spindle into two diametrically arranged axially extending circumferential regions, it is possible to manufacture the spindle using two mold halves, with the mold parting surface of the injection molding tool extending in an axial plane of the spindle, which axially intersects the circumferential regions where the thread profile is missing.

[0032] For example, the hollow spindle has a flattened portion parallel to the axis on its outer circumference in the area of ​​a parting line. This also enables simplified manufacturing and tolerance for any minor inaccuracies that may arise in the parting line at the mold parting line between the two mold halves.

[0033] A linear actuator according to the improved spindle concept can be formed with a spindle system according to one of the described embodiments. The linear actuator comprises a telescopic tube system surrounding the spindle system, wherein the telescopic tube system comprises an outer tube and at least one inner tube arranged coaxially to the outer tube and at least partially surrounded by the outer tube. A bearing is configured to transmit axial forces, in particular to transmit thrust or tensile forces, between the hollow spindle of the spindle system and the outer tube. A rotational movement of the spindle system does not cause a rotational movement of the outer tube.

[0034] Such a linear actuator can be installed in a piece of furniture, such as a table or even in a bed.

[0035] The improved spindle concept is explained in more detail below using exemplary embodiments with reference to the drawings. Similar elements or elements with the same functions are designated by the same reference numerals. Therefore, a repeated explanation of individual elements may be omitted.

[0036] Here we show, partly simplified: Fig. 1 an embodiment of a table with two telescopic columns; Fig. 2 an embodiment of a spindle system in the extended state; Fig. 3 an embodiment of a spindle system in retracted state; Fig. 4 a detail of the spindle system from Fig. 2; Fig. 5 another detail of the spindle system Fig. 2; Fig. 6 another detail of the spindle system from Fig. 2; Fig. 7 Details of a hollow spindle design; Fig. 8 Section through the hollow spindle from Fig. 7 with bearing seat and bearing; Fig. 9 a top view of the hollow spindle from Fig. 7 with the profiling of the inside of the hollow spindle; Fig. 10 a representation of an exemplary shaft-hub connection between the inner shaft with its sliding element and the hollow spindle; Fig. 11 a plan view of an embodiment of a sliding element; Fig. 12a another top view of the hollow spindle from Fig. 7; Fig. 12b a section through the view in Fig. 12a; Fig. 13a a design of a sliding element with compensating elements; Fig. 13b another view of the sliding element from Fig. 13a; Fig. 14a shows a representation of a shape of a sliding element in a groove; Fig. 14b shows a further illustration of a sliding element in a groove; and Fig. 15 another form of a sliding element.

[0037] The Fig. Figure 1 shows an electrically height-adjustable table 100 with, for example, two columns 110, 110'. Each column 110, 110' is connected to a table base 120, 120' and the table top 130. Each column 110, 110' comprises a three-stage telescopic housing with coaxial profile tubes and a linear actuator (in Fig. 1 not shown).

[0038] Fig. 2 shows an example of a spindle system 290 with an inner shaft 200, a hollow spindle 250 and an inner tube 220, each located within the outer tube 210. The spindle system in Fig. 2 is shown in the extended state.

[0039] Fig. 3 also shows the spindle system 290 from Fig. 2 in a slightly enlarged view and in the retracted state. You can see a drive spindle nut 240 and a bearing, in this example a ball bearing 260, which are required for mounting the outer tube 210.

[0040] The hollow spindle 250 has a sliding guide 280 for the inner tube 220 at one end, which is rotationally fixedly connected to the hollow spindle 250. The inner tube 220 is smooth on the inside, and the sliding guide 280 enables a rotational movement of the inner tube 220 relative to the hollow spindle 250.

[0041] At the lower end of the inner shaft 200, a sliding element 270 is provided, which creates a positive and axially displaceable connection with the hollow spindle 250. With a drive, such as an electric motor, at the upper end of the shaft 200, a linear actuator is created.

[0042] Fig. 4 shows an enlarged view of the spindle system 290 from Fig. 2 and Fig. 3 in the area of ​​the hollow spindle nut 245.

[0043] The hollow spindle 250 has a hollow spindle nut 245. The hollow spindle nut 245 has a bracket 246 for the rotationally fixed mounting of the inner tube 220 and a bracket 247 for the rotationally fixed mounting of the outer tube 210. The bracket 247 for the rotationally fixed mounting of the outer tube 210 is ribbed and engages with a rib on the inside of the outer tube 210. The bracket 246 for the rotationally fixed mounting of the inner tube 220 has a shoulder onto which the inner tube 220 is placed.

[0044] The drive spindle nut 240 has a shoulder for receiving the outer tube 210. The drive spindle nut 240 has grippers or snappers 248 for gripping the ball bearing 260 and thereby holding the hollow spindle 250 to the drive spindle nut 240.

[0045] In the Fig. Figure 5 shows a detailed view of the hollow spindle 250 with the ball bearing 260. The hollow spindle 250 and the ball bearing 260 are firmly connected to each other. The ball bearing 260 allows the outer tube 210 (not shown here) to be rotatably mounted. This enables rotation of the hollow spindle 250 within the outer tube 210.

[0046] The hollow spindle 250 has one or more drivers, e.g. ribs or knobs 255 on its inside, into the correspondingly shaped drivers on the outside of the sliding element 270 (not visible here, see Fig. 11) and transmit the torque of the inner shaft 200 to the hollow spindle 250.

[0047] In the Fig. 5, the inner tube 220 is mounted on the hollow spindle nut 245. The outer tube 210 is not mounted, but the bracket 247 for the outer tube is visible.

[0048] In the Fig. 6, the inner shaft 200 is visible with a sliding element 270 attached to the inner shaft 200. The sliding element 270 is attached to the end remote from the drive and comprises one or more drivers (better seen in Fig. 11), e.g. ribs. The sliding element 270 is connected to the inner shaft 200 in a rotationally fixed but axially movable manner. The drivers of the sliding element 270 transmit the torque via one or more drivers 255, better visible in Fig. 5, on the inside of the hollow spindle 250 to the hollow spindle 250. The sliding element 270 engages in the drivers 255 on the inner side of the hollow spindle 250 and forms an axially displaceable, positive shaft-hub connection between the inner shaft 200 of the spindle system and the hollow spindle 250.

[0049] The Fig. 7 shows a side view of the hollow spindle 250. The hollow spindle has a bearing 260, which in the illustrated embodiment is designed as a ball bearing.

[0050] The hollow spindle is manufactured using an injection molding tool, which has two mold halves joined together at a parting line. The two mold halves form a thread profile 310 on the outer circumference. The thread profile 310 is interrupted in two circumferential areas by a flattened portion 300', 300''. Fig. 7 only the front of the two flats. The second flat is located on the invisible rear side of the hollow spindle. The two circumferential areas run parallel to the axis, extend over the entire length of the thread, and are arranged diametrically opposite each other.

[0051] In the area where the parting plane intersects the hollow spindle 250 axially, the thread profile is flattened parallel to the axis. These flattened portions 300' and 300'' thus accommodate any minor inaccuracies that may arise in the parting plane at the mold parting line between the two mold halves. The injection points for injecting the plastic into the mold are also located in the areas of the flattened portions 300' and 300''.

[0052] This eliminates the need for the spindle with the plastic thread to be demolded from the injection molding tool in a complex manner by axially unscrewing the spindle from the mold. By interrupting the thread profile of the hollow spindle into two diametrically arranged, axially extending circumferential regions, it is possible to produce the spindle through two mold halves, with the mold parting surface of the injection molding tool running in an axial plane of the spindle that axially intersects the circumferential regions where the thread profile is missing. With respect to the plane of the mold parting surface, the thread profile 310 has no undercut due to the flattened areas 300', 300'', so that the mold can be separated and demolded in this parting surface.

[0053] The Fig. Figure 8 shows a section through the hollow spindle. Before the injection molding process, the bearing 260 is inserted into the mold to produce the bearing 260 and the hollow spindle 250 in a single step and from a single casting. During injection molding, the bearing 260 is firmly bonded to the plastic of the hollow spindle by injecting the plastic compound firmly onto the outer surface of the insert. After curing, both the hollow spindle and the bearing seat with axial stops 320', 320'' on both sides for the bearing are manufactured in the same injection molding process. The bearing is overmolded with the same plastic from which the hollow spindle was molded. The axial stops 320', 320'' run circumferentially along the outer surface of the hollow spindle 250.

[0054] In one embodiment, the bearing 260 can be formed as a ball or roller bearing, which is firmly connected to the plastic of the hollow spindle 250 after injection.

[0055] In one embodiment, a particularly metallic inner ring of the ball or roller bearing is at least partially overmolded with the plastic of the hollow spindle 250.

[0056] In one version, a plastic inner ring of the ball or roller bearing is fused to the bearing seat.

[0057] In one embodiment, the bearing 260 can be formed as a plain bearing (not shown) which, after injection molding, is firmly connected to the plastic of the hollow spindle 250.

[0058] In addition to the two mold halves, the injection mold also contains one or two steel cores, which are overmolded with plastic during the injection process. The one or two steel cores are removed after the injection process to leave the hollow interior of the hollow spindle. The one or two steel cores have a profile on their outside that Fig. 9 shown profiling 330 is produced on the inside of the hollow spindle 250.

[0059] The profiling 330 of the hollow spindle inner side comprises one or more drivers 255', 255'', 255''', 255''''. These drivers can, for example, have the shape of ribs, wedges, teeth, or non-circular profiles.

[0060] Each driver 255', 255'', 255''', 255'''' has two flanks 340', 340''.

[0061] The Fig. Figure 9 shows a plan view of the hollow spindle and shows, in addition to the profiling, one side of a ball bearing with one of the two axial, rotating and uninterrupted stops 320'.

[0062] The Fig. 10 shows, in addition to the hollow spindle 250, a sliding element 270 with a profile on the outside, which has one or more drivers 350', 350'', which engage in the drivers 255', 255'', 255''', 255'''' of the profile on the inside of the hollow spindle and produce an axially displaceable, positive shaft-hub connection between the hollow spindle 250 and the inner shaft 200 with the aid of the sliding element 270 which is connected to it in a rotationally fixed manner.

[0063] The Fig. 11 shows a plan view of one embodiment of a sliding element 270. This embodiment comprises, for example, four drivers 350', 350'', 350''', 350''''. Each driver has two flanks, analogous to the drivers of the hollow spindle.

[0064] The sliding element 270 is pushed onto the inner shaft 200 and pressed, for example.

[0065] The Fig. Figure 12a shows a view of the profiling of the hollow spindle 250 with one or more drivers 255', 255'', 255''', 255''''. The view is not to scale for clarity.

[0066] Using a driver 255' of the one or more drivers of the hollow spindle, it is shown that the two flanks 340' and 340'' of the driver 255' have a varying distance a1, a2 over the length of the hollow spindle, i.e. along the axial direction.

[0067] In one embodiment, the distance a1 between the flanks 340', 340'' of the driver 255' in the center of the hollow spindle 250 is smaller than the distance a2 at each of the two ends of the hollow spindle 250.

[0068] In an analogous manner, all drivers 255', 255'', 255''', 255'''' have such a varying distance between their respective flanks.

[0069] In a further embodiment, the inner diameter varies between any two opposing drivers 255'', 255''' of the profiling of the inside of the hollow spindle over the length of the hollow spindle 250.

[0070] In particular, the inner diameter d1 in the center of the hollow spindle is smaller than the inner diameter d2 at each of the two ends of the hollow spindle 250. For example, the inner diameter decreases continuously from the outer ends of the hollow spindle 250 towards the center, i.e. it becomes continuously smaller.

[0071] Due to the varying distances between the flanks of the drivers 255', 255'', 255''', 255'''', the width of the grooves between the drivers also varies. Using a groove 345, Fig. 12a and Fig. 12b shows how the width of the groove 345 runs.

[0072] The Fig. 12b shows a section along the section plane S from the Fig. 12a. The width of the groove 345 is greater in the area of ​​the two ends of the hollow spindle E1, E2 than in the center M of the hollow spindle 250. The width of the groove 345 decreases continuously from the outer ends E1, E2 of the hollow spindle 250 towards the center M, thus becoming continuously smaller.

[0073] This applies analogously to all grooves of the profiling of the hollow spindle 250.

[0074] The one or more drivers 255', 255'', 255''', 255'''' and the one or more grooves 345 of the profile 330 of the inner side of the hollow spindle 250 are formed by one or two steel cores that are overmolded with plastic during the injection molding process. The varying spacing, widths, and diameters of the one or more grooves and one or more drivers shown make it possible to remove the one or two steel cores from the hollow spindle 250 after the injection molding process.

[0075] Fig. Figure 12b shows the groove width profile for a groove 345, as it is created by the preferred use of two steel cores during the injection molding process. The groove width profile resembles the shape of two mirrored isosceles trapezoids. During the injection molding process, the first steel core extends from the first end E1 to the center M of the hollow spindle. The second steel core extends from the second end E2 to the center M of the hollow spindle 250.

[0076] Alternatively, only one steel core can be used. In this case, the groove width at one end of the hollow spindle is larger, in particular twice as large as when using two steel cores. This increases the minimum achievable diameter of the hollow spindle and thus the diameter of the linear actuator or lifting column.

[0077] In order to achieve a positive shaft-hub connection between the sliding element 270 and the hollow spindle 250 over the entire axial displacement range of the sliding element 270 despite the different width ratios along the grooves, the sliding element 270 has, in one embodiment, one or more elastic compensating elements 360', 360'', 360''', 360'''' in order to minimize the radial play between the one or more drivers 350', 350'', 350''', 350'''' of the sliding element and the one or more drivers 255', 255'' 255''', 255'''' of the hollow spindle 250 over the entire length of the hollow spindle 250.

[0078] The Fig. 13a and Fig. 13b show an embodiment of a sliding element 270 with one or more elastic compensating elements 360', 360'', 360''', 360'''' in different views.

[0079] The one or more elastic compensation elements 360', 360'', 360''', 360'''' are each located in a groove 345 of the profiling of the hollow spindle 250 and nestle laterally against two flanks 340''', 340'''' of the drivers of the hollow spindle, as shown in Fig. 14a and Fig. 14b shown. Fig. 14a and Fig. 14b shows the sliding element 270 at two different positions within the axial displacement range of the sliding element. In the area of ​​the center M of the hollow spindle, the elastic compensating elements 360', 360'', 360''', 360'''' are pressed closer together than in the end regions, e.g., E1.

[0080] In one embodiment, each of the one or more compensating elements comprises 360', 360'', 360''', 360'''', as in Fig. 13a and Fig. 13b, one or more legs, in particular two legs, which are spaced apart from each other and elastic.

[0081] In an alternative embodiment, each of the one or more compensating elements comprises 360', 360'', 360''', 360'''', as in Fig. 15, an elastic, self-contained, in particular annular or elliptical part. List of reference symbols 100 table 110, 110' column 120, 120' table base 130 table top 200 internal shaft 210 outer tube 220 inner tube 240 Drive spindle nut 245 hollow spindle nut 246 Bracket for inner tube 247 Bracket for outer tube 248 grippers for ball bearings 250 hollow spindle 255', 255'' 255''', 255'''' Carrier 260 ball bearings 270 sliding element 280 sliding guide 290 spindle system 300', 300'' flattening 310 thread profile 320', 320'', 320''', 320'''' Bearing seat stops 330 Profiling 340', 340'', 340''', 340'''' flanks 345 groove 350', 350'', 350''', 350'''' Carrier 360', 360'', 360''', 360'''' compensation elements S cutting plane E1, E2 end of the hollow spindle M Center of the hollow spindle

Claims

[1] A spindle system with a hollow spindle for a linear actuator, where - the linear actuator comprises a telescopic tube system surrounding the spindle system, wherein the telescopic tube system comprises an outer tube and at least one inner tube arranged coaxially to the outer tube and at least partially surrounded by the outer tube; - a bearing for transmitting axial forces, in particular for transmitting thrust or tensile forces, is arranged between the hollow spindle and the outer tube; and - a rotational movement of the spindle system does not cause a rotational movement of the outer tube; whereby the hollow spindle - at least partially surrounds an internal shaft of the spindle system; - is connected to the internal shaft of the spindle system by a positive and axially movable shaft-hub connection; - has an external thread on one outer side; and - has a bearing seat for the bearing; and wherein - the shaft-hub connection is formed by a profiling of the inner shaft and a profiling of the inside of the hollow spindle; - the profiling of the inner shaft and the profiling of the inside of the hollow spindle are each created by one or more drivers which form the shaft-hub connection; - the one or more drivers of the profiling of the inner shaft are formed by drivers on a sliding element which is connected in a rotationally fixed manner to the inner shaft; - the sliding element has one or more elastic compensating elements which fit snugly against the drivers of the hollow spindle in order to minimize the radial play between the one or more drivers of the sliding element and the one or more drivers of the hollow spindle over the entire length of the hollow spindle; and - the external thread of the hollow spindle, the one or more drivers of the hollow spindle and the bearing seat are made from a single casting and consist of the same plastic. [2] The spindle system according to claim 1, wherein the one or more drivers are each formed in the form of ribs, wedges, teeth or non-circular profiles. [3] The spindle system according to claim 1 or 2, wherein each of the drivers of the profiling of the inner side of the hollow spindle has two flanks, the distance between which varies in the axial direction of the hollow spindle. [4] The spindle system according to one of claims 1 to 3, wherein the hollow spindle has a first and a second end and wherein each of the drivers of the profiling of the inner side of the hollow spindle has two flanks, the distance between which is smaller between the first and the second end, in particular in the middle of the hollow spindle, than at the first and the second end of the hollow spindle. [5] The spindle system according to one of claims 1 to 4, wherein an inner diameter of the hollow spindle varies between opposite drivers of the profiling of the inner side of the hollow spindle in the axial direction of the hollow spindle. [6] The spindle system according to claim 5, wherein the hollow spindle has a first and a second end and wherein the inner diameter between opposite drivers of the profiling of the inner side of the hollow spindle between the first and the second end, in particular in the middle of the hollow spindle, is smaller than at the first and the second end of the hollow spindle. [7] The spindle system according to one of claims 1 to 6, wherein each of the one or more elastic compensating elements fits laterally against the flanks of the drivers of the hollow spindle. [8] The spindle system according to one of claims 1 to 7, wherein each of the one or more elastic compensating elements comprises one or more, in particular two, legs which are spaced apart from one another and are elastic. [9] The spindle system according to one of claims 1 to 7, wherein each of the one or more elastic compensating elements comprises an elastic, self-contained, in particular annular or elliptical, part. [10] The spindle system according to one of claims 1 to 9, wherein the bearing seat of the hollow spindle has an axial stop on both sides relative to the inner ring of a rolling bearing or relative to a plain bearing, in particular a disc-shaped plain bearing. [11] The spindle system according to claim 10, wherein there is a material connection between at least a part of the bearing and the bilateral axial stop of the bearing seat of the hollow spindle. [12] The spindle system according to claim 11, wherein an inner ring of a rolling bearing is at least partially overmolded with the plastic of the hollow spindle. [13] The spindle system according to claim 11, wherein an inner ring of a rolling bearing, in particular an inner ring made of plastic, is fused to the bearing seat. [14] The spindle system according to claim 11, wherein a plain bearing is at least partially overmolded with the plastic of the hollow spindle. [15] The spindle system according to one of claims 1 to 14, wherein the external thread of the hollow spindle is interrupted in two circumferential regions of the hollow spindle, which extend over an entire axial length of the external thread and are arranged diametrically to each other with respect to the hollow spindle axis. [16] The spindle system according to one of claims 1 to 15, wherein the hollow spindle has an axially parallel flattening in the region of a parting plane on its outer circumference. [17] A linear actuator with a spindle system according to any one of claims 1 to 16, wherein - the linear actuator comprises a telescopic tube system surrounding the spindle system, wherein the telescopic tube system comprises an outer tube and at least one inner tube arranged coaxially to the outer tube and at least partially surrounded by the outer tube; - a bearing for transmitting axial forces, in particular for transmitting thrust or tensile forces, is arranged between the hollow spindle of the spindle system and the outer tube; and - a rotational movement of the spindle system does not cause a rotational movement of the outer tube. [18] A piece of furniture, in particular a table (100) or bed, with at least one linear actuator according to claim 17.

Images