ADJUSTMENT DEVICE COMPRISING AN ASYMMETRICALLY ACTING BRAKE ASSEMBLY AND VEHICLE SEAT HAVING SUCH AN ADJUSTMENT DEVICE

Abstract

It is provided an adjustment device for a vehicle seat, comprising an output element to which a drive torque can be transferred, and a brake assembly for locking the output element and absorbing, via at least two brake elements adjustably mounted in a brake housing of the brake assembly, forces applied to the output element on the output side, wherein locking, provided via the brake assembly, of the output element can be released in order to rotate the output element in a direction of rotation when a drive torque is applied on the drive side, and, in order to lock the output element, the brake elements are in a locking position in which, when forces are applied on the output side via the output element and are acting in a direction of rotation, at least one of the brake elements bears frictionally against a brake surface of the brake housing.

Claims

1. An adjustment device for a vehicle seat, comprising an output element, a drive assembly for introducing a drive torque to be transferred to the output element into the adjustment device, and a brake assembly for locking the output element and absorbing, via at least two brake elements adjustably mounted in a brake housing of the brake assembly, forces applied to the output element on the output side, wherein, when a drive torque is introduced via the drive assembly, a locking, provided via the brake assembly, of the output element can be released and the output element can be rotated along a direction of rotation, and, in order to lock the output element, the brake elements are in a locking position, in which, when forces are applied on the output side via the output element and are acting along a direction of rotation, at least one of the brake elements bears frictionally against a brake surface of the brake housing, wherein a maximum braking torque counteracting an adjustment of the output element is provided via the brake assembly, which braking torque varies in magnitude according to the direction of rotation along which a force acting on the output element on the output side acts.

2. The adjustment device according to claim 1, wherein a first maximum braking torque provided via the brake assembly and counteracting a rotation of the output element along a first direction of rotation is smaller than a second maximum braking torque provided via the brake assembly and counteracting a rotation of the output element along an opposite, second direction of rotation.

3. The adjustment device according to claim 1, wherein in the brake assembly, depending on the direction of rotation, different numbers and/or differently dimensioned brake portions of the brake elements bear frictionally against the brake surface.

4. The adjustment device according to claim 1, wherein at least three brake elements are provided, each of which comprises at least one brake portion for frictional contact with the brake surface of the brake housing.

5. The adjustment device according to claim 4, wherein a first group of brake elements is provided, the brake portions of which bear frictionally against the brake surface when forces act on the output element on the output side in order to rotate the output element along a first direction of rotation, and a second group of brake elements is provided, the brake portions of which bear frictionally against the brake surface when forces act on the output element on the output side in order to rotate the output element along an opposite, second direction of rotation, wherein the second group comprises at least one brake element and/or at least one brake portion more than the first group.

6. The adjustment device according to claim 5, wherein both the brake elements of the first group and the brake elements of the second group can be displaced from a respective locking position into a release position via a driver element of the brake assembly that can be driven by the drive assembly, in order to release the locking of the output element provided via the brake assembly when a drive torque is introduced via the drive assembly.

7. The adjustment device according to claim 6, wherein the driver element comprises a plurality of driver portions, each of which is assigned to at least one brake element for releasing the respective locking mechanism provided via this.

8. The adjustment device according to claim 7, wherein a driver portion can each be brought into contact with a contact portion of the assigned brake element when a drive torque is introduced via the drive assembly, for the displacement of an assigned brake element into the respective release position.

9. The adjustment device according to claim 8, wherein the driver element is rotatable about an axis of rotation and a driver portion for a brake element of the first group can only be brought into contact with a contact portion lying in a first drive direction of rotation, while a driver portion for a brake element of the second group can only be brought into contact with a contact portion lying in an opposite, second drive direction of rotation.

10. The adjustment device according to claim 1, wherein the brake elements of the brake assembly are tiltably mounted within the brake housing between a respective locking position and a release position, in which a locking of the output element is released via the respective brake element.

11. The adjustment device according to claim, wherein the brake elements of the brake assembly can, in their respective locking position, each bear against an assigned contact surface of the output element via a convexly curved contact portion.

12. The adjustment device according to claim 1, characterized in that the brake assembly comprises exactly three brake elements and the output element has a hexagonal cross-section with three separate contact surfaces for the three brake elements.

13. The adjustment device according to claim 7, wherein the driver element comprises at least one driver portion that can be brought into contact with two different brake elements depending on the direction of action of the introduced drive torque.

14. The adjustment device according to claim 7, wherein the driver element comprises at least one driver portion that can be brought into contact with two different brake elements depending on the direction of action of the introduced drive torque, wherein the brake elements are configured as rotationally symmetrical clamping bodies.

15. The adjustment device according to claim 1, wherein the brake assembly comprises at least two spring elements, via which brake elements of the brake assembly are preloaded against each other, wherein the spring forces acting on the brake elements and applied by the spring elements are of different magnitudes.

16. The adjustment device according to claim 4, wherein the brake assembly comprises at least two spring elements with different spring constants, of which a first spring element with a first spring constant preloads a first brake element and a second brake element of the at least three brake elements against each other and a second spring element with a higher, second spring constant preloads a third brake element and the first brake element of the at least three brake elements against each other.

17. The adjustment device according to claim 14, wherein the brake assembly comprises at least two spring elements with different spring constants, of which a first spring element with a first spring constant preloads a first brake element and a second brake element of the at least three brake elements against each other and a second spring element with a higher, second spring constant preloads a third brake element and the second brake element of the at least three brake elements against each other.

18. The adjustment device according to claim 1, wherein a control element is provided for transferring the drive torque introduced via the drive assembly into the output element, which control element is form-fittingly connected to a) a coupling portion of the output element or b) a coupling element of the adjustment device, which coupling element is connected to the output element in a rotationally fixed manner.

19. The adjustment device according to claim 6, wherein a control element is provided for transferring the drive torque introduced via the drive assembly into the output element, which control element is form-fittingly connected to a) a coupling portion of the output element or b) a coupling element of the adjustment device, which coupling element is connected to the output element in a rotationally fixed manner, wherein the control element is connected in a rotationally fixed manner to the driver element.

20. A vehicle seat, comprising an adjustment device according to claim 1 for seat height adjustment.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The attached figures illustrate exemplary possible variants of the proposed solution.

[0036] FIG. 1 shows an exploded view of a first variant of a proposed adjustment device.

[0037] FIG. 2A shows, in a side view of a brake assembly, the adjustment device from FIG. 1.

[0038] FIG. 2B shows a sectional view along the line of section A-A from FIG. 2A showing three brake segments of the brake assembly, each of which is tiltably mounted and preloaded against each other by two compression springs with different spring constants.

[0039] FIG. 3 shows, in a perspective view, a second variant of a proposed adjustment device with separate drive and brake assemblies.

[0040] FIG. 4A shows the adjustment device from FIG. 3 in a side view in the assembled state.

[0041] FIG. 4B shows a sectional view of the adjustment device along the line of section A-A from FIG. 4A showing several sets of three brake rollers each, which are arranged circumferentially in a gap within the brake assembly and are preloaded against each other via spring elements with different spring constants.

[0042] FIG. 5 shows an enlarged detail of the sectional view of FIG. 4B.

[0043] FIG. 6 shows the drive assembly of the adjustment device from FIG. 3, looking at a driver element for actuating the brake assembly.

DETAILED DESCRIPTION

[0044] FIG. 1 shows an exploded view of a first exemplary embodiment of a proposed adjustment device V with a drive assembly 1 and a brake assembly 2, wherein the brake assembly 2 is configured as an asymmetrically acting shoe brake with severalin the present case a total of threebrake elements in the form of brake segments 6.1, 6.2 and 6.3. The adjustment device V of FIG. 1 is provided for manual seat height adjustment on a vehicle seat. The adjustment direction V here permits the introduction of a drive torque via the drive assembly 1 and the transfer of this drive torque to an output element in the form of an (output) pinion 7. The pinion 7 is rotatably mounted about a central axis of rotation M of the adjustment device V and is form-fittingly received in a pinion opening 107 of a control disc 10 of the drive assembly 1 via a coupling portion 71. In this way, a drive torque can be transferred from the control disc 10 to the pinion 7.

[0045] The drive torque can then be transferred to a seat structure of the vehicle seat via an output portion 72 of the pinion 7. For this purpose, for example, a toothing of the output portion 72 can engage in a toothed segment of the vehicle seat for the seat height adjustment. Depending on the direction of rotation in which the drive torque acts on the drive assembly 1, the pinion 7 is rotated in one or the other direction of rotation about the central axis of rotation M and thus, for example, clockwise or counter-clockwise. For example, a roller freewheel drive or a pawl drive can be provided for introducing the drive torque. However, other configurations are of course also possible.

[0046] The brake assembly 2 of the device V is provided to prevent the pinion 7 from being unintentionally displaced when the seat height is assumed. Via the brake assembly 2, the pinion 7 is locked in an assumed adjustment position when the drive torque is not applied. This locking serves in particular also for the collision-proof locking of an adjustment mechanism provided for the seat height adjustment in order to prevent the set seat height of the vehicle seat from changing due to the loads occurring in the event of a collision. Via the brake assembly 2, the pinion 7 is locked against rotation when forces are applied to the pinion 7 on the output side. If, for example, the output portion 72 receives a torque from the seat structure via a toothed segment engaging in the teeth of the output portion, this torque is absorbed via the brake assembly 2. The brake segments 6.1, 6.2 and 6.3 of the brake assembly 2 (as well as the brake rollers 6.1, 6.2 and 6.3 of the variant yet to be explained below) consequently apply a braking force counteracting the rotation of the pinion 7 in order to block the pinion 7 against rotation in the event of resultant forces acting on the output side.

[0047] For the locking of the pinion 7, the brake segments 6.1, 6.2 and 6.3 can each bear frictionally against a radially inner circumferential brake surface 30 of a brake housing 3, in which the brake segments 6.1, 6.2 and 6.3 are adjustably mounted. The three brake segments 6.1, 6.2 and 6.3 are arranged here around the central axis of rotation M of the adjustment direction V and are in contact with the coupling portion 71 of the pinion 7 via radially inner contact portions 6.11, 6.21 and 6.31 of a brake segment 6.1, 6.2 or 6.3 (compare also FIG. 2B). The brake segments 6.1, 6.2 and 6.3 are preloaded here against each other in the circumferential direction via compression springs 4 and 5 of different strengths in order to provide maximum braking torques of different magnitudes in the present case depending on the direction of rotation in which a resultant force applied to the output side of the pinion 7 acts. Thus, in one direction of rotation two brake segments 6.1 and 6.2 are active, while in the other direction of rotation only the other brake segment 6.3 is active, as will be explained in greater detail below.

[0048] In order to release the locking of the pinion 7 via the brake segments 6.1, 6.2 and 6.3 when a drive torque is applied, the control disc 10 is connected to a driver disc 11 for conjoint rotation. This driver disc 11 has a plurality of axially protruding driver projections 111, 112 and 113, which can act on the brake segments 6.1, 6.2 and 6.3 when the driver disc 11 rotates about the axis of rotation M, in order to displace them from their respective locking positions and thus release the pinion 7.

[0049] The brake assembly 2 is shown in side view in FIG. 2A. This shows in particular that the pinion 7 with its output portion 72 and in particular the toothing formed on it protrudes axially from the brake housing 3 along the central center axis or axis of rotation M of the adjustment device V.

[0050] FIG. 2B shows a sectional view through the brake assembly 2 along the line of section A-A of FIG. 2A. It is particularly evident from FIG. 2B that each brake segment 6.1, 6.2 and 6.3 has, in each case, a convex, radially inwardly curved contact portion 6.11, 6.21 or 6.31 with respect to the axis of rotation M, via which the respective brake segment 6.1, 6.2 or 6.3 bears against an assigned contact surface 7.11, 7.12 or 7.13 of the coupling portion 71 of the pinion 7. By contrast, an adjacent secondary portion 6.12, 6.22 or 6.32 of a brake segment 6.1, 6.2 or 6.3, which is also convexly curved, is slightly spaced radially from the assigned contact surface 7.11, 7.12 or 7.13 of the coupling portion 71. Each brake segment 6.1, 6.2 and 6.3 is thus mounted within the brake housing 3 such that it can tilt about a tilt axis which runs parallel to the axis of rotation M but is located radially further outwards. From a locking position of a brake segment 6.1, 6.2 or 6.3 shown in FIG. 2B, the respective brake segment 6.1, 6.2 or 6.3 can be tilted here into a release position by rolling the respective contact portion 6.11, 6.21 or 6.31 on the contact surface 7.11, 7.12 or 7.13 in the direction of the spaced-apart secondary portion 6.12, 6.22 or 6.32, in order to release a locking of the pinion 7 relative to the brake housing 3 by the respective brake segment 6.1, 6.2 or 6.3.

[0051] First and second brake segments 6.1 and 6.2 of the brake assembly 2 are in this case preloaded in a first direction of rotation cw (clockwise in FIG. 2B) into their respective tilted locking positions via the spring tension applied by the compression springs 4 and 5, while a third brake segment 6.3 is preloaded in the opposite, second direction of rotation ccw (counter-clockwise) into its locking position. Thus, a compression spring 4 with a higher spring constant is provided between the first brake segment 6.1 and the third brake segment 6.3. A second, weaker compression spring 5 in turn preloads the first and second brake segments 6.1 and 6.2 relative to each other. Due to the higher spring constant of the stronger compression spring 4, the first brake segment 6.1 and the third brake segment 6.3 are consequently preloaded in opposite directions of rotation cw and ccw. The higher preloading force of the compression spring 4 also leads here to a preloading of the second brake segment 6.2 over the weaker compression spring 5 in the same direction of rotation cw as the first brake segment 6.1.

[0052] Each brake segment 6.1, 6.2 and 6.3 is accordingly in frictional contact with the brake surface 30 of the brake housing 3 via a radially outer brake portion 6.1a, 6.2a or 6.3a. The respective brake portion 6.1a, 6.2a, 6.3a is in each case closer to the contact portion 6.11, 6.21 or 6.31 of the respective brake segment 6.1, 6.2 or 6.3 which is in contact with the contact surface 7.11, 7.12 or 7.13. If a torque introduced on the output side is thus transferred from the cross-sectionally hexagonal coupling portion 71 of the pinion 7 to an adjacent brake segment 6.1, 6.2 or 6.3, the respective brake segmentdepending on the direction of rotationis frictionally supported on the brake surface 30 via the assigned brake portion 6.1a, 6.2a or 6.3a and hereby blocks the pinion 7 against rotation about the axis of rotation M. Here, in the case of a force introduced on the output side in the first direction of rotation cw, a locking is ensured via the third brake segment 6.3, while in the case of a force applied to the output side in the second direction of rotation ccw, locking of the pinion 7 is ensured via the two first and second brake segments 6.1 and 6.3.

[0053] If, for example, a torque is introduced in the first direction of rotation cw from a seat structure by a toothed segment engaging in the teeth of the output portion 72 of the pinion 7, a load is transferred to the one, third brake segment 6.3 via the transmission contour formed with the coupling portion 71. Via the stronger compression spring 4, the third brake segment 6.3 is supported against the adjacent, counter-rotating first brake segment 6.1 and preloaded in the brake housing 3. There is thus a play-free load introduction from the pinion 7 into the third brake segment 6.3 and the load can be absorbed directly by the brake housing 3. Here, the position of a contact point of the third brake segment 6.3 at its contact portion 6.31 to the pinion 7 as well as contact points of the third brake segment 6.3 to the brake housing 3 define the normal forces which exert a self-locking, frictionally engaged blocking effect on the pinion 7 at its coupling portion 71 according to their geometric position. Consequently, if a force is introduced on the output side in the first direction of rotation cw, a force is only introduced into the third brake segment 6.3, but not into the first and second brake segments 6.1 and 6.2.

[0054] If, on the other hand, a force acting in the opposite, second direction of rotation ccw is introduced into the pinion 7 on the output side via the brake assembly 2 when the locking is in effect, the associated load is transferred to the first and second brake segments 6.1 and 6.2 via the coupling portion 71 of the pinion 7 and its transfer contour. Here, the first and second brake segments 6.1 and 6.2 are supported against the counter-rotating third brake segment 6.3 via the compression springs 4 and 5 and are preloaded in the brake housing 3. Due to the higher force level of the compression spring 4, which is provided between the first brake segment 6.1 and the third brake segment 6.3, a correct orientation of the positions of the first and second brake segments 6.1 and 6.2 in the brake housing 3 is ensured. This also ensures a play-free load introduction from the pinion 7 into the first and second brake segments 6.1 and 6.2, so that the load can thus be absorbed by the brake housing 3. In addition, a self-locking, frictionally engaged blocking effect on the pinion 7 is also ensured in order to secure the pinion 7 against rotation about the axis of rotation M in the second direction of rotation ccw. Consequently, if a force is introduced on the output side in the second direction of rotation ccw, a force is only introduced into the first and second brake segments 6.1 and 6.2, but not into the third brake segment 6.3.

[0055] In the case of the adjustment device V shown and in particular its brake assembly 2, different large maximum braking torques are thus provided via a different number of brake segments or brake portions which interact with the brake surface 30 of the brake housing 3, depending on the direction of rotation cw or ccw along which a resultant force applied to the pinion 7 acts. This makes it possible to take into account in a cost- and resource-efficient manner the fact that, in the cases of application intended for the adjustment direction V, it can typically be assumed that greater forces are to be absorbed in one direction of rotation cw (main load direction) than in the opposite direction of rotation ccw (secondary load direction). The asymmetrically acting brake assembly 2 takes this circumstance into account efficiently, so that an oversizing for absorbing loads along the secondary load direction can be avoided and the device V can thus be configured to be compact and cost-effective.

[0056] For example, a maximum braking torque can be provided in a main load direction that is more than 30% higher, in particular more than 50% higher, than a maximum braking torque in a secondary load direction. For example, a maximum braking torque in the main load direction is greater than 140 Nm, in particular greater than 160 Nm or 180 Nm. In a variant, a maximum braking torque in the main load direction is, for example, in the range of 180 Nm to 210 Nm, in particular 200 Nm. By contrast, a maximum braking torque in the secondary load direction is, for example, less than 160 Nm, in particular less than 140 Nm or 120 Nm. In one variant, a maximum braking torque in the secondary load direction is, for example, in the range of 90 Nm to 110 Nm, in particular 100 Nm.

[0057] In this context, it is also advantageous that the natural vibration behavior of the components can be well tuned by the compression springs 4 and 5 of different strength. Thus, a natural frequency of the brake segments depends, among other things, on an applied spring preload. In the variant shown, the first brake segment 6.1 can thus act better in a different frequency band than the second brake segment 6.2, and vice versa. Therefore, an asymmetrical shoe brake realized via the brake assembly 2 is also less susceptible to an independent adjustment of the brake segments 6.1 and 6.2 during a frequency excitation.

[0058] Although the brake segments 6.1, 6.2 and 6.3 are configured identically in the variant shown, they can also be configured differently. Furthermore, the spring elements 4 and 5 can also be configured differently. Alternatively or additionally, the spring elements 4 and 5 can be exchangeable and replaceable in the shown brake assembly 2. In this way, for example, a brake assembly 2 which is provided for one (left or right) longitudinal side of a vehicle seat and which is configured for a main load direction and secondary load direction decisive for this longitudinal side can be used for an opposite (right or left) longitudinal side of a vehicle seat by simply changing the spring elements 4 and 5. This includes in particular a variant in which a kit is provided via a brake assembly 2 with the brake housing 3 and brake segments 6.1, 6.2 and 6.3 tiltably mounted therein. With such a kit, during assembly of the brake assembly 2 and the assigned adjustment device V, the compression springs 4 and 5 are then inserted at different positioned into the gaps existing between the individual brake segments 6.1, 6.2 and 6.3, depending on the intended use, in order to preload the brake segments 6.1, 6.2 and 6.3 rotating in opposite directions to each other into the respective locking positions accordingly (i.e. one brake segment in one direction of rotation and a pair of brake segments in the other direction of rotation).

[0059] For releasing the locking of the pinion 7 provided via the brake assembly 2, the driver disc 11 already mentioned above is provided with its axially protruding driver projections 111, 112 and 113. Each of these driver projections 111, 112 and 113 engages in an assigned recess 6.10, 6.20 or 6.30 of a brake segment 6.1, 6.2 or 6.3, which is formed radially outwardly on a respective brake segment 6.1, 6.2 or 6.3. Each driver projection 111, 112 and 113 is thus located within a recess 6.10, 6.20 or 6.30 between two circumferentially opposite portions 6.10a/6.10b, 6.20a/6.20b or 6.30a/6.30b of the respective brake segment 6.1, 6.2 and 6.3. In this case, a distance of a respective driver projection 111, 112 or 113 to one of these two portions is smaller, so that contacting of the respective portion is possible in the respective direction of rotation cw or ccw.

[0060] For example, the driver projections 111 and 112 are each at a shorter distance from a contact portion 6.10a or 6.20a of the first or second brake segment 6.1 and 6.2 lying in the second direction of rotation ccw. The distance to an opposite portion 6.10b or 6.20b of the respective recess 6.10 or 6.20 is consequently larger, in particular larger than a distance which the driver projection 113 for the third brake segment has to a contact portion 6.30a of the third brake segment 6.3 lying in the first direction of rotation cw. If the driver disc 11 is rotated via the control disc 10 in the first direction of rotation cw, this (third) driver projection 113 acts on the third brake segment 6.3 via the contact 6.30a without the other driver projections 111, 112 acting on the brake segments 6.1 and 6.2 assigned to them. The rotation of the driver disc 11 in the first direction of rotation cw tilts the first brake segment 6.3 from its locking position into a release position and releases the locking of the pinion 7. The fact that the driver projections 111, 112 are not in contact with the opposite portions 6.10b and 6.20b of the first and second brake segments 6.1 and 6.2 assigned to them is irrelevant here. In the first (drive) direction of rotation cw, no locking of the pinion 7 is provided via the first and second brake segments 6.1, 6.2.

[0061] If, on the other hand, the driver disc 11 is rotated about the axis of rotation M in the opposite, second (drive) direction of rotation ccw under an applied drive torque, the (first and second) driver projections 111 and 112 come into contact with the contact portions 6.10a and 6.20a of the first and second brake segments 6.1 and 6.2 assigned to them. This allows the brake segments 6.1 and 6.2 to be tilted from their respective locking position into a release position. A locking of the pinion 7 for a rotation along the second (drive) direction of rotation ccw is thus released and the pinion 7 can be rotated by the control disc 10 about the axis of rotation M.

[0062] In the event of a drive torque introduced on the drive side in the first (drive) direction of rotation cw, the third brake segment 6.3 tilts against the stronger compression spring 4 by a defined idle travel (until the assigned driver projection 113 rests against the contact portion 6.30a of the third brake segment 6.3) and compresses the compression spring 4. The self-locking blocking effect defined via the contact points between the third brake segment 6.3 and the brake housing 3 is consequently cancelled and the pinion 7 can be actuated rotationally in the direction of rotation cw. With the drive torque acting in the opposite (drive) direction of rotation ccw, the first and second brake segments 6.1 and 6.3 in turn tilt by a defined idle travel against the two compression springs 4 and 5 and compress them. Here too, the self-locking blocking effect between the brake segments 6.1 and 6.2 and the brake housing 3 is thus cancelled. Since the counter-rotating third brake segment 6.3 does not develop a blocking effect in this direction of rotation ccw, the pinion 7 can then be actuated rotationally in the direction of rotation ccw.

[0063] FIGS. 3 to 6 show a further variant of a proposed adjustment device V, in which an asymmetrical braking effect is provided by the brake assembly 2 according to an identical principle. Instead of the brake segments 6.1, 6.2 and 6.3 provided in the variant of FIGS. 1 to 2A, rotationally symmetrical clamping bodies are provided in the variant of FIGS. 3 to 6, here in the form of brake rollers 6.1, 6.2 and 6.3. Here, several sets of three brake rollers each are provided distributed circumferentially around a coupling portion 71 of the pinion 7. The brake rollers 6.1, 6.2 and 6.3 are accommodated here in an annular gap g between the coupling portion 71 and the brake surface 30 of the brake housing 3 in order to act in a clamping manner in a respective locking position and thus to lock the pinion 7.

[0064] FIG. 3 first shows here, in a partially exploded view, the adjustment device V with the brake assembly 2 integrating an asymmetrically acting roller brake. The drive assembly 1 is shown disassembled from the brake assembly 2. FIG. 4A shows the assembled state of the adjustment device V in a side view.

[0065] FIG. 4B shows a sectional view of the brake assembly 2 along the line of section A-A of FIG. 4A. In particular, it can be seen from this that in the present variant a first brake roller 6.1 and a second brake roller 6.2 are always preloaded against each other via a weaker spring 5 (with a smaller spring constant), while the second brake roller 6.2 is always preloaded against a third brake roller 6.3 via a stronger spring 4. Analogously to the previously described variant of FIGS. 1 to 2A, two brake elementshere in the form of the first and second brake rollers 6.1 and 6.2are thus preloaded against each other in pairs via an intermediate weaker spring element 5 and are thus jointly provided for locking the pinion 7 in a direction of rotation ccw (in this case in the counter-clockwise direction). A third brake element in the form of the brake roller 6.3, which is preloaded against the second brake roller 6.2 via the stronger spring 4, in turn takes over the locking of the pinion 7 in the opposite direction of rotation cw (in this case in the clockwise direction).

[0066] The first and second brake rollers 6.1, 6.2 are thussimilarly to the brake segments 6.1 and 6.2 of the variant of FIGS. 1 to 2Apart of a second group of brake elements of the brake assembly 2, which bear frictionally against the brake surface 30 when forces act on the pinion 7 on the drive side to rotate the pinion 7 in a (second) direction of rotation cw (ccw in the variant of FIGS. 1 to 2A), and to block the pinion 7 against such rotation. The brake rollers 6.3 are furthermoreanalogously to the third brake segment 6.3part of a first group of brake elements of the brake assembly 2, the brake portions of which bear frictionally against the brake surface 30 when output-side forces act on the pinion 7 to rotate the pinion 7 in an opposite (first) direction of rotation ccw, and to block the pinion 7 against a corresponding rotation.

[0067] In the variant of FIGS. 3 to 6, three sets of first, second and third brake rollers 6.1, 6.2 and 6.3 respectively are arranged around the circumference of the coupling portion 71 in the annular gap g in order to be able to apply braking forces to the drive pinion 7 that act in a manner distributed evenly over the circumference. An axially protruding driver projection 111a, 112a or 113a of a driver disc 11 engages in a respective gap between two sets of brake rollers. Furthermore, between each of the first and second brake rollers 6.1 and 6.2, an additional driver projection 111b, 112b or 113b is provided. This additional driver projection 111b, 112b or 113b is configured to be shortened in the axial direction compared to the other driver bar 111a, 112a or 113a, so that the additional, shortened driver projection 111b, 112b or 113b does not collide with the spring 5 present between the first and second brake rollers 6.1 and 6.2.

[0068] As can also be seen from the enlarged sectional view of a detail in FIG. 5, the brake rollers 6.1, 6.2 and 6.3 are in a respective locking position via the transfer contour of thehere cross-sectionally nonagonalcoupling portion 71 of the pinion 7 at the contact surfaces 7.11, 7.12 and 7.13 assigned to them, respectively, into which position the brake rollers 6.1, 6.2 and 6.3 are preloaded via the springs 4 and 5. In these locking positions, the brake rollers 6.1, 6.2 and 6.3 are each present between the coupling portion 71 and the brake surface 30 in a clamping manner in only one of the two possible directions of rotation cw, ccw. For example, the annular gap g tapers locally in the region of the contact surfaces 7.11, 7.12 assigned to the first and second brake rollers 6.1 and 6.2 in the second direction of rotation ccw (counter-clockwise). By contrast, the annular gap g tapers locally in the first direction of rotation cw (clockwise) via the transfer contour of the contact surface 7.13 for the third brake rollers 6.3. Via the stronger spring 4, the first and second brake rollers 6.1 and 6.2 are thus preloaded into a locking position in the second direction of rotation ccw, while the third brake rollers 6.3 are each preloaded into a locking position in the opposite, first direction of rotation cw. Accordingly, the first and second brake rollers 6.1, 6.2 are in clamping contact with the brake surface 30 and the respective assigned contact surface 7.11, 7.12 with their outer circumferential surfaces acting as brake portions 6.1a and 6.2a, in order to lock the pinion 7 when a force is introduced into the pinion 7 on the output side and acts in the first direction of rotation cw. By contrast, the outer surface of the third brake rollers 6.3, which acts as a brake portion 6.3a, bears frictionally against the radially outer brake surface 30 and the respective assigned, radially inner contact surface 7.13 of the pinion 7 in order to counteract a rotation of the pinion 7 in the event of a force acting in the second direction of rotation ccw (counter-clockwise) on the output side.

[0069] Also in the brake assembly 2 of FIGS. 3 to 6, for example, the number of brake portions 6.1a, 6.2a acting in a braking and thus locking manner in the main load direction and the number of brake elements 6.1, 6.2 acting in a locking manner is, in total, twice as large as the number of brake portions 6.3a and assigned brake elements 6.3 provided for locking in the opposite direction of rotation. This makes it possible to considerably reduce the loads acting on the respective surfaces of the brake elements, via which they can slide along the brake housing 3, and thus the wear, depending on the direction of loading. This is also accompanied by the possibility of using more favorable materials for the smaller brake elements and a resultant increased performance.

[0070] Incidentally, an improved natural oscillation behavior can also be observed in the variant of FIGS. 3 to 6 due to the different strength of the springs 4 and 5. For example, a first brake roller 6.1 works better in a different frequency band than a second brake roller 6.2, and vice versa. Consequently, the roller brake provided via the brake assembly 2 is also less susceptible in total to an independent adjustment under frequency excitation.

[0071] The driver disc 11 provided for releasing a locking at the brake assembly 2 is illustrated again in greater detail in FIG. 6. The driver disc 11 is also connected here, for example via several pin connections, to a control disc 10 for conjoint rotation. This control disc 10 again has a pinion opening 107, in which a coupling element in the form of a coupling ring 8, which is connected for conjoint rotation to the pinion 7, engages form-fittingly. For this purpose, the coupling ring 8 has several radially protruding extensions which engage form-fittingly in assigned recesses of the pinion opening 107. In this way, a rotational movement of the control disc 10 is converted into a rotational movement of the coupling ring 8 and thus a rotational movement of the pinion 7 when a drive torque acts on the control disc 10 on the drive side. In this case, the driver disc 10 is then also entrained in the respective drive direction of rotation cw or ccw, acting on the different brake rollers 6.1, 6.2 and 6.3 via its different driver projections 111a/b, 112a/b and 113a/b (depending on the direction of rotation) in order to release the locking of the pinion 7.

[0072] Here, the driver portions 111a, 111b, 112a, 112b, 113a and 113b act in each case on the first and second brake rollers 6.1 and 6.2 of a brake roller pair to release a locking of the pinion 7 when a drive torque is to be transferred in the first (drive) direction of rotation cw. This displaces the first and second brake rollers 6.1, 6.2 relative to the coupling portion 71 of the pinion 7 against the preload forces applied by the springs 4 and 5, so that the first and second brake rollers 6.1, 6.2 are no longer in clamping contact with the brake housing 3 and the coupling portion 71.

[0073] By contrast, with an oppositely acting drive torque in the (drive) direction of rotation ccw, only the (first) driver projections 111a, 112a and 113a of the driver disc 11 act on the third brake rollers 6.3 in this direction of rotation ccw against the preload force of the stronger spring 4. This displaces the third brake rollers 6.3 in the direction of rotation ccw relative to the coupling portion 71 of the pinion 7, so that the third brake rollers 6.3 are no longer in clamping contact with the brake housing 3.

LIST OF REFERENCE CHARACTERS

[0074] 1 drive assembly [0075] 10 control disc (control element) [0076] 107 pinion opening (form-fit opening) [0077] 11 driver disc (driver element) [0078] 111, 112, 113, driver protrusion (driver portion) [0079] 111a/b, 112a/b, 113a/b [0080] 2 brake assembly [0081] 3 brake housing [0082] 30 brake surface [0083] 4 (stronger) spring [0084] 5 (weaker) spring [0085] 6.1, 6.2, 6.3 brake segment (brake element) [0086] 6.1, 6.2, 6.3 brake roller (brake element) [0087] 6.10, 6.20, 6.30 recess [0088] 6.10a, 6.20a, 6.30a contact portion [0089] 6.10b, 6.20b, 6.30b opposite portion [0090] 6.11, 6.21, 6.31 contact portion [0091] 6.12, 6.22, 6.32 secondary portion [0092] 6.1a, 6.2a., 6.3a brake portion [0093] 7 pinion (output element) [0094] 71 coupling portion [0095] 7.11, 7.12, 7.13 contact surface [0096] 72 output portion [0097] 8 coupling ring (coupling element) [0098] ccw second direction of rotation [0099] cw first direction of rotation [0100] g annular gap [0101] M center axis/axis of rotation [0102] V adjustment device