Planetary gearbox and actuator for an actively adjustable roll stabilizer

Abstract

Planetary gear (1), in particular for use on an actuator (2) of an adjustable roll stabilizer (3) for a motor vehicle, wherein the planetary gear (1) comprises a sun gear (21; 31; 41), a ring gear (22; 32; 42) and a planet carrier (23; 33) which are arranged coaxially to one another with respect to a common axis of rotation (7), wherein the sun gear (21; 31; 41) is in meshing tooth engagement with several planets (27; 37; 47) which are each rotatably mounted on the planet carrier (23; 33) about a planet axis (24; 34; 44) along an inner tooth engagement line (26; 36; 46) and the planets (27; 37; 47) are each in meshing tooth engagement with an inner side of the ring gear (22; 32; 42) along an outer tooth engagement line (25; 35; 45) are in intermeshing tooth engagement, wherein the inner tooth engagement line (26; 36; 46) and the outer tooth engagement line (25; 35; 45) are inclined to each other, deviating from parallelism and forming a wedge angle (α), wherein the planets (27; 37;47) each have a conical toothing with a cone angle (β) directed opposite to the wedge angle (α) and the planet axis (24; 34; 44) of each of the planets (27; 37; 47) lies on the angle bisector of the wedge angle (α), characterized in that the ring gear (42) is formed with a cylindrical toothing, wherein the planet axes (44) are offset relative to the axis of rotation (7) by an angle of inclination (ψ).

Description

[0001] The invention relates to a planetary gear, in particular for use on an actuator of an adjustable roll stabilizer for a motor vehicle according to the features of the preamble of claim 1. The invention further relates to an actuator for an actively adjustable roll stabilizer according to the features of claim 11.

[0002] Planetary gears are known from the prior art. Among other applications, planetary gears are used in automotive engineering, particularly in chassis technology, for example, in the actuator of an adjustable roll stabilizer for a motor vehicle. In general, a planetary gear comprises a sun gear, a ring gear, and a planet carrier, which are arranged coaxially with respect to a common axis of rotation. The sun gear engages with several planets, each rotatably mounted on the planet carrier about a planet axis, along an inner tooth engagement line. The planets themselves engage with the inner side of the ring gear along an outer tooth engagement line.In the context of the present invention, a tooth engagement line is understood to be a line extending along the meshing tooth flanks, approximately in the axial direction, which runs centrally within the mutual engagement area of ​​the tooth flanks of the respective gear pair.

[0003] In the operational use of an adjustable roll stabilizer on a motor vehicle, its actuator, and consequently the planetary gear used within it, is subjected to highly fluctuating loads, particularly those changing direction. A change in the direction of rotation within the planetary gear can lead to disruptive noise, as conventional planetary gears are often manufactured with at least a small amount of play to facilitate assembly. This can result in a change of flank between the gear components when the load on the gear is reversed, causing a flank change and a so-called flank change shock, which in turn can lead to disruptive noise.

[0004] From DE 10 2017 208 800 B3, a measure is known for using a split planetary gear within a planetary gearbox used in an adjustable roll stabilizer. This split gear consists of two partial gears that can be rotationally preloaded against each other by means of a spring element, so that the split gear generates a (deliberate) preload when installed within the planetary gearbox. This preload is intended to ensure backlash-free operation of the gearbox or at least reduce any existing backlash in order to prevent disruptive noise during changes in the direction of rotation.

[0005] Another measure known from DE 10 2021 120 463 A1 consists of tilting the planets of a planetary gear slightly relative to the axis of rotation of the planetary gear by means of a bolt elastically mounted on the planet carrier, in order to reduce the gear backlash.

[0006] A planetary gear unit according to the features of the preamble of claim 1 is known from DE 10 2010 046 958 A1. Reference is also made to the planetary gear units previously known from EP 0 084 197 A1, DE 37 21 064 A1 and JP H07 - 158 721 A.

[0007] It is an object of the present invention to provide a planetary gear of the type mentioned above, with which backlash within the planetary gear can be reduced in a different way. The planetary gear should be easy to manufacture; in particular, the toothing of the ring gear should be easy to manufacture. In addition, an actuator for an adjustable roll stabilizer, the gearbox of which incorporates such a planetary gear, is to be provided.

[0008] The aforementioned problem is initially solved by a planetary gear according to the features of claim 1. This is a planetary gear comprising a sun gear, a ring gear, and a planet carrier, which are arranged coaxially with respect to a common axis of rotation. The sun gear engages with several planets, each rotatably mounted on the planet carrier about a planet axis, along an inner tooth engagement line, and the planets engage with an inner face of the ring gear along an outer tooth engagement line. For the purposes of this invention, a tooth engagement line is defined as a line extending along the meshing tooth flanks, approximately in the axial direction, which runs centrally within the mutual engagement area of ​​the tooth flanks of the respective gear pair.The "inner line of tooth engagement" runs between the sun gear and the planet gear, and the "outer line of tooth engagement" runs between the ring gear and the planet gear. According to the invention, in the planetary gear, the inner and outer lines of tooth engagement are inclined relative to each other, deviating from parallelism and forming a wedge angle. Each planet gear has a conical tooth profile with a cone angle opposite to the wedge angle, and the planet axis of each planet lies on the bisector of the wedge angle. The planetary gear is further characterized by the fact that the ring gear has cylindrical teeth, and the planet axes are offset from the axis of rotation by an angle of inclination.

[0009] This arrangement of the planetary gear advantageously provides a way to effectively minimize backlash within the planetary gear, which, in conventional planetary gears, can lead to disruptive noise during changes in the direction of rotation between the planet and sun gear and / or between the planet and ring gear. In contrast to the geometry of conventional planetary gears, in which cylindrical teeth are formed on both the sun gear and planet gears, such that the inner line of engagement (between sun gear and planet) and the outer line of engagement (between ring gear and planet) are aligned parallel to each other and parallel to the axis of rotation of the planetary gear, the planetary gear according to the invention features an inclined orientation of the inner and outer lines of engagement.

[0010] With regard to the planets arranged between the sun gear and the ring gear and rolling along them, the inner tooth engagement line and the outer tooth engagement line form a wedge-like boundary according to the invention in such a way that a respective planet, on which a conical toothing with a cone angle opposite to the wedge angle is formed according to the invention, comes into a tooth engagement with the sun gear and the ring gear with less backlash the closer the planet is moved along the angle bisector into the tapering wedge angle.

[0011] The design according to the invention ensures that any backlash between the planet and sun gear or between the planet and ring gear can be influenced by changing the axial position of the planet. By positioning the planet in a stop position, for example by applying appropriate axial preload, in which the planet contacts both the sun gear and the ring gear without backlash, backlash-free operation is achieved within the planetary gear set. This advantageously avoids or at least reduces flank-shifting and the associated noise generation within the planetary gear set.

[0012] The planetary gear according to the invention can be designed in different ways. According to an advantageous embodiment of the planetary gear, not only do the planets each have conical teeth, but the sun gear also has conical teeth with a conical angle. Advantageously, the sun gear is oriented such that the conical teeth of the sun gear are oriented in the opposite direction to the conical teeth of the planet gear.

[0013] The planetary gear set is advantageously characterized by means for axially preloading the planets relative to their planetary axis to reduce backlash, the preload being exerted opposite to the opening direction of the wedge angle formed by the mutually inclined tooth engagement lines. In other words, the axial preload is thus applied such that the planets are pressed axially – along their planetary axis – into the wedge formed by the inner and outer tooth engagement lines. This ensures in a simple manner that the desired backlash-free operation is maintained even under various operating conditions (especially different load conditions) of the planetary gear set. At the same time, it ensures that jamming within the gear set is avoided, since the axial preload allows for elastic movement of the planets in the axial direction.

[0014] Advantageously, the aforementioned means each comprise a spring element acting between the planet and the planet carrier, which exerts an axial preload on the planet. For example, the spring element can be arranged between the planet and the planet carrier.

[0015] To prevent jamming, particularly self-locking within the planetary gear set, it would be advantageous to also provide means that at least limit movement of the planets against the opening direction of the wedge angle. In the simplest case, this could be a stop that rigidly (absolutely) limits the axial movement of the planet. Alternatively or additionally, a spring element acting in the opposite direction, i.e., in the opening direction of the wedge angle, could be used. This could, for example, be designed and positioned so that it only engages as a stop buffer once the planet has reached a certain axial position (preventing self-locking).Alternatively, it could be a spring element acting in the opposite direction, i.e., in the opening direction of the wedge angle, which is designed and positioned, for example, in such a way that the planet is held in an ideal working range while ensuring a certain axial mobility, which on the one hand ensures a desired reduction in backlash, and on the other hand avoids jamming within the gearbox.

[0016] The advantageous effect of the inclination described in the invention for achieving backlash-free operation within the planetary gear can be advantageously achieved by the conical toothing of the planets having a foot cone angle of 4° to 5°, preferably of about 4.5°.

[0017] According to the invention, the ring gear is designed with cylindrical teeth, wherein the planetary axes are offset from the axis of rotation by an angle of inclination. Accordingly, the outer tooth engagement line is also parallel to the axis of rotation of the planetary gear. An advantage of this design is that the toothing of the ring gear can be manufactured in a simple manner, since it is a cylindrical toothing.

[0018] In geometric terms, the conical toothing of the sun gear in the latter case has a cone angle that is twice as large as the inclination angle of the planetary axes.

[0019] In the planetary gear system according to the invention, the planets are advantageously rotatably mounted relative to the planet carrier, in particular by means of bolts attached to the planet carrier.

[0020] The planetary gear according to the invention is advantageously arranged in a housing, in particular an actuator housing, wherein the ring gear is preferably formed on a housing wall or is attached to the housing.

[0021] The planetary gear described above can be used for various purposes. It is particularly useful for reducing an input speed provided by a drive motor or an upstream gear stage to a correspondingly lower output speed.

[0022] The aforementioned problem is also solved by an actuator for an actively adjustable roll stabilizer according to the features of claim 11. This actuator comprises an electric motor and a gearbox that can be connected to the motor for drive purposes, in order to rotate a stabilizer section of the roll stabilizer about an axis of rotation. The gearbox is, in particular, of a multi-stage design, and at least on one gearbox stage, especially on its output-side gearbox stage, the gearbox comprises a planetary gearbox of the type described above.

[0023] In the actuator according to the invention, the transmission advantageously has a planetary gear of the type described above on the output-side gear stage and on a gear stage upstream of this.

[0024] The invention is explained in more detail below with reference to the accompanying drawing. Further advantageous effects of the invention will also become apparent from this drawing. The drawing shows: Fig. 1 an actively adjustable roll stabilizer in a simplified schematic perspective representation, Fig. 2 a part of an actuator of an actively adjustable roll stabilizer in lateral section, Fig. 3a and Fig. 3b Components of a third gear stage, Fig. 4a and Fig. 4b Components of a gear stage according to the invention.

[0025] Fig. Figure 1 shows a schematic, simplified perspective view of an actively adjustable roll stabilizer 3 with coupled wheel suspensions and wheels. The roll stabilizer 3 can be attached to a motor vehicle (not shown) in a manner known per se to influence the roll behavior of the equipped motor vehicle, in particular to cause or counteract roll of the vehicle body.

[0026] A left wheel 12a is mounted vertically relative to a vehicle body (not shown) via a left wheel suspension 13a. Similarly, a right wheel 12b is mounted vertically relative to a right wheel suspension 13b. The actively adjustable roll stabilizer 3 comprises as its essential elements a left stabilizer section 11a, a right stabilizer section 11b, and an actuator 2 arranged between them. At one end opposite the actuator 2, the left stabilizer section 11a is coupled to the left wheel suspension 13a, while at the other end opposite the actuator 2, the right stabilizer section 11b is coupled to the right wheel suspension 13b.

[0027] The actuator 2 has a substantially cylindrical basic shape (shown here in a simplified form) and extends along an axis of rotation 7. While the left stabilizer section 11a is fixedly connected to an actuator housing 19 of the actuator 2 (rotationally fixed), the left stabilizer section 11b is connected to an output-side gearbox output of the actuator 2. Thus, the right stabilizer section 11b can be rotated about the axis of rotation 7 relative to the left stabilizer section 11a in a manner known per se. For this purpose, an electric motor 14 is arranged inside the actuator 2, which is in drive connection with a gearbox 15 also arranged inside the actuator 2, which in turn is connected on its output side to the right stabilizer section 11b.By operating the electric motor 14, the gearbox 15 can be set in motion to rotate the stabilizer sections 11a and 11b about the axis of rotation 7 against each other, thereby influencing the roll behavior of the motor vehicle equipped with the roll stabilizer 3.

[0028] At the in Fig. In the simplified representation of actuator 2, a multi-stage, in particular three-stage, planetary gear unit 15 is used, for example. This gear unit can advantageously have a planetary gear unit according to the invention on at least one or even several of its gear stages. For a more detailed explanation, reference is made to the following Fig. Reference is made to sections 2 to 4b and their corresponding descriptions.

[0029] Fig. Figure 2 shows a section of an actuator 2. In consideration of the present invention, only a region of the actuator is shown, in which the gearbox 15 is housed. As in Fig. As can be seen in Figure 2, the actuator 2 extends along and, in particular, rotationally symmetrically with respect to an axis of rotation 7. In the left-hand part of the image, there is an electric motor 14, which is indicated only by a reference symbol for illustrative purposes. In the right-hand part of the image, a right-hand stabilizer section 11b is indicated by a reference symbol; this section can be attached to an output element 16 of the actuator 12. In the Fig. The actuator shown in section 2 could be an actuator that is attached to a device such as the one shown in the diagram. Fig. 1 explained actively adjustable roll stabilizer 3 can be used advantageously.

[0030] The in Fig. The actuator 2 shown is externally bounded by an actuator housing 19, which in the illustrated embodiment is designed in two parts. The actuator housing 19 surrounds the electric motor 14 and the gearbox 15 and protects them from external environmental influences.

[0031] In a coaxial arrangement with respect to the axis of rotation 7, a three-stage planetary gear unit 15 is arranged next to the electric motor 14. This unit comprises a first gear stage 10, a second gear stage 20, and a third gear stage 30. The electric motor 14 drives the first gear stage 10, which is a planetary gear unit with (conventional) cylindrical teeth on the sun gear, ring gear, and planet gears, via a motor shaft 18. A second gear stage 20 is driven by the first gear stage 10, and this second gear stage 20 is in turn driven by the third gear stage 30. In the illustrated embodiment, a planet carrier 33 of the third gear stage also serves as the output element 16 of the actuator 2. The output element 16 is rotatably mounted relative to the actuator housing 19 via a bearing 17 in the form of a double-groove ball bearing.

[0032] While the first gear stage 10 of the multi-stage planetary gear 15 is of conventional design and therefore does not require further explanation here, the second gear stage 20 and the third gear stage 30 each have a planetary gear according to the invention, which is explained below.

[0033] The planetary gear set of the second planetary gear stage 20 comprises a sun gear 21, a ring gear 22 formed on the actuator housing 19, and a planet carrier 23, which are arranged coaxially with respect to the common axis of rotation 7. The sun gear 21 meshes with several planets 27, each rotatably mounted on the planet carrier 23 about a planet axis 24, along an inner tooth engagement line 26. The planets 27 also mesh with an inner face of the ring gear 22 along an outer tooth engagement line 25. As indicated by the auxiliary lines, the inner tooth engagement line 26 and the outer tooth engagement line 25—unlike in the first gear stage 10—are not parallel and are inclined to each other, forming a wedge angle α. Accordingly, the extensions of the tooth engagement lines 26 and 25 meet at a point on the left side of the image, which is no longer shown.The planets 27 of the second gear stage 20 each have a conical toothing with a cone angle β directed against the wedge angle α, and the planet axes 24 of the planets 27 each lie on the angle bisector of the wedge angle α.

[0034] In the second gear stage 20, the sun gear 21 also has a conical tooth profile with a cone angle φ. In the illustrated embodiment, the conical tooth profile of the planets 27 has a root cone angle of 4.5 degrees.

[0035] It can also be seen that a conical internal toothing with a foot cone angle is formed on the ring gear 22, which is directed opposite to the conical toothing of the planets, such that the planet axes 24 of the planets 27 are each aligned parallel to the axis of rotation.

[0036] The planets 27 are rotatably mounted relative to the planet carrier 23 by means of bolts 29 attached to the planet carrier 23. The second gear stage 20 serves to reduce an input speed provided by the upstream gear stage 10 into a correspondingly reduced output speed, in order to make this in turn available to the third gear stage 30.

[0037] The third gear stage 30 is designed in a fundamentally similar manner. A sun gear 31, a ring gear 32, and a planet carrier 33 are arranged coaxially with respect to the common axis of rotation 7. The sun gear 31 meshes with several planets 37, each rotatably mounted on the planet carrier 33 about a planet axis 34, along an inner tooth engagement line 36. The planets 37 mesh with each inner face of the ring gear 32 along an outer tooth engagement line 35. Here, too, the inner tooth engagement line 36 and the outer tooth engagement line 35 are inclined relative to each other, deviating from parallelism and forming a wedge angle α. The planets 37 each have a conical toothing with a cone angle β directed opposite to the wedge angle α, with the planetary axes 34 of each of the planets 37 lying on the angle bisector of the wedge angle α.

[0038] The sun gear 34 has a conical toothing with a cone angle φ.

[0039] In the third gear stage 30, it is clearly visible that means are provided to axially preload the planets 37 with respect to their planetary axis 34 in order to reduce backlash. The preload is exerted opposite to the opening direction of the wedge angle α formed by the mutually inclined tooth engagement lines 35, 36. For this purpose, a spring element 38 is provided between each planet 37 and planet carrier 33, which exerts an axial preload on the respective planet 37. In this way, by means of the axial preload of the planet 37, backlash-free operation can be ensured for the gear stage 30, thereby preventing disruptive noises that occur, for example, during a tooth flank change during a change of direction within the gearbox.

[0040] The conical gearing of the planets 37 of the third gear stage 30 preferably has a root cone angle of 4.5 degrees. As in Fig. As shown in Figure 2, the inner tooth engagement line 36 and the outer tooth engagement line 35 of the gear stage 30 continue onto the inner tooth engagement line 26 and the outer tooth engagement line 25, respectively, of the second gear stage 20. This design allows for easy assembly of the second gear stage 20 and the third gear stage 30, as they can be inserted one after the other in an axial direction into the actuator housing 19 (as shown in the figure, from right to left).

[0041] In the Fig. 3a and Fig. 3b shows individual components of the third gear stage 30 shown separately for illustrative purposes. While Fig. 3a, each with reference to the axis of rotation 7, show the sun gear 31 with a cone angle φ, the planet 37 with a cone angle β, and the ring gear 32. Fig. 3b shows only two planets 37 with their respective planetary axes 34. This corresponds to the information already provided by Fig. The design of the third gear stage 30 described in section 2 also shows the features in the Fig. 3a and Fig. The components of gear stage 30 shown in 3b exhibit a comparable geometry. In particular, it can be seen that due to a [missing information] on the ring gear 32 (compare [missing information]), Fig. 3a) In the conical internal gearing, both an outer tooth engagement line 35 and an inner tooth engagement line 36 are inclined relative to each other, deviating from parallelism and forming a wedge angle α. The planets 37 also have conical gearing with a cone angle β. The planetary axes 34 of the planets 37 lie on an angle bisector of the wedge angle α. Based on the Fig. 3a and Fig. In the embodiment shown in 3b, the planetary axes 34 are parallel to the rotation axis 7.

[0042] In contrast to the previous one based on the Fig. 2, Fig. 3a and Fig. The embodiments shown in 3b are in the Fig. 4a and Fig. 4b shows an embodiment according to the invention for the design of the planets on a planetary gear according to the invention. Fig. 4a and Fig. Section 4b refers to an alternative planetary stage 40 that can be used in a planetary gear set according to the invention. Accordingly, the planetary gear set comprises a sun gear 41, a ring gear 42, and a planet carrier (not shown), which are arranged coaxially with respect to a common axis of rotation 7. The sun gear 41 engages with several planets 47, each rotatably mounted about a planetary axis 44, along a tooth engagement line 46. The planets 47 engage with an inner face of the ring gear 42 along an outer tooth engagement line 45. Again, the inner tooth engagement line 46 and the outer tooth engagement line 45 are inclined relative to each other, deviating from parallelism and forming a wedge angle α. The planets 47 each have conical teeth with a cone angle β, which is opposite to the wedge angle α.The planetary axis 44 of each of the planets 47 lies on the angle bisector of the wedge angle α.

[0043] Unlike gear stages 20 and 30, the following applies to the Fig. 4a and Fig. In the planetary stage 40 shown in Figure 4b, the ring gear 42 is designed with cylindrical teeth. Accordingly, the outer line of tooth engagement 45 runs parallel to the axis of rotation 7. The planetary axes 44 are offset from the axis of rotation 7 by an angle of inclination ψ. The conical teeth of the sun gear 41 have a cone angle φ that is twice as large as the angle of inclination ψ of the planetary axes. Reference sign 1 planetary gear 2 Actuator 3. Roll stabilizer 4 sun wheel 5 Ring gear 6 planetary carriers 7. Axis of rotation 8 Planetary axis 9 planets 10 first gear stage 11a; 11b left stabilizer section; right stabilizer section 12a; 12b left wheel; right wheel 13a; 13b left wheel suspension; right wheel suspension 14 Electric motor 15 gearboxes 16 Output element 17 warehouses 18 Motor shaft 19 actuator housings 20 second gear stage 21 Sun wheel 22 Ring gear 23 planetary carriers 24 Planetary axis 25 outer tooth engagement line 26 inner tooth engagement line 27 Planet 29 bolts 30 third gear stage 31 Sun wheel 32 Ring gear 33 planetary carriers 34 Planetary axis 35 outer tooth engagement line 36 inner tooth engagement line 37 Planet 38 Spring element 39 bolts 40th planetary stage 41 Sun wheel 42 Ring gear 44 Planetary axis 45 outer tooth engagement line 46 inner tooth engagement line 47 Planet α Wedge angle β Cone angle (planets) φ Cone angle (Sun) ψ Angle of inclination

Claims

[1] Planetary gear (1), in particular for use on an actuator (2) of an adjustable roll stabilizer (3) for a motor vehicle, wherein the planetary gear (1) comprises a sun gear (21; 31; 41), a ring gear (22; 32; 42) and a planet carrier (23; 33) which are arranged coaxially to each other with respect to a common axis of rotation (7), wherein the sun gear (21; 31; 41) is in meshing tooth engagement with several planets (27; 37; 47) which are each rotatably mounted on the planet carrier (23; 33) about a planet axis (24; 34; 44) along an inner tooth engagement line (26; 36; 46) and the planets (27; 37; 47) are each in meshing tooth engagement with an inner side of the ring gear (22; 32; 42) along an outer tooth engagement line (25; 35; 45) are in intermeshing tooth engagement, wherein the inner tooth engagement line (26; 36; 46) and the outer tooth engagement line (25; 35; 45) are inclined to each other, deviating from parallelism and forming a wedge angle (α), wherein the planets (27; 37;47) each have a conical toothing with a cone angle (β) directed opposite to the wedge angle (α) and the planetary axis (24; 34; 44) of each of the planets (27; 37; 47) lies on the angle bisector of the wedge angle (α), ; characterized by , that the ring gear (42) is designed with a cylindrical toothing, wherein the planet axes (44) are offset relative to the axis of rotation (7) by an angle of inclination (ψ). [2] Planetary gear according to claim 1, characterized by , that the sun gear (21; 31; 41) has a conical toothing with a cone angle (φ). [3] Planetary gear unit according to claim 1 or 2, characterized by Means (38) to axially preload the planets (37) with respect to their planetary axis (34) to reduce backlash, the preload being exerted against the opening direction of the wedge angle (α) formed by the mutually inclined tooth engagement lines (35, 36). [4] Planetary gear according to claim 3, characterized by, that the means comprise a spring element (38) acting between planet (37) and planet carrier (33), which exerts a preload acting in an axial direction on the planet (37). [5] Planetary gear unit according to claim 3 or 4, characterized by Means that at least limit axial movement of the planets against the opening direction of the wedge angle (α), in particular by forming a rigid and / or elastic stop. [6] Planetary gear set according to any of the preceding claims, characterized by , that the conical interlocking of the planets (27; 37) has a foot cone angle of 4° to 5°, particularly preferably of about 4.5°. [7] Planetary gear set according to any of the preceding claims, characterized by , that the conical toothing of the sun wheel (41) has a cone angle (φ) that is twice as large as the inclination angle (ψ) of the planetary axes (44). [8] Planetary gear set according to any of the preceding claims, characterized by, that the planets (27; 37) are rotatably mounted relative to the planet carrier (23; 33) in particular by means of bolts (29; 39) attached to the planet carrier (23; 33). [9] Planetary gear set according to any of the preceding claims, characterized by that this is arranged in a housing, in particular an actuator housing (19), wherein preferably the ring gear (22; 23) is formed on a housing wall or is attached to the housing. [10] Planetary gear set according to any one of the preceding claims, characterized by , that this serves to reduce an input speed provided by a drive motor (14) or by an upstream gear stage (20; 10) into a correspondingly reduced output speed. [11] Actuator (2) for an actively adjustable roll stabilizer (3), comprising an electric motor (14) and a gearbox (15) that can be connected to the drive, in order to be able to rotate a stabilizer section (11b) of the roll stabilizer (3) about an axis of rotation (7), wherein the gearbox (15) is in particular multi-stage and has at least on one gearbox stage (20; 30), in particular on its output-side gearbox stage (30), a planetary gearbox (1) according to one of the preceding claims. [12] Actuator according to claim 11, characterized by , that the transmission (15) has a planetary gear (1) according to one of the preceding claims on the output-side transmission stage (30) and on a transmission stage (20) upstream of this.

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