Actuator for an adjustable roll stabilizer

Abstract

Actuator (2) for an actively adjustable roll stabilizer (1), comprising a drive unit (8) and a drive-connected gearbox, which is designed as a multi-stage planetary gearbox with several interconnected planetary gear stages (10, 20, 30) and can be connected on the output side to a stabilizer section (5b) of the roll stabilizer (1), characterized in that tooth engagement areas of one of the planetary gear stages (30) are located within a gearbox chamber (38), which is sealed against other areas (10, 20) of the gearbox and is filled to a considerable extent with a lubricant (36) to dampen operating-related vibrations.

Description

[0001] The invention relates to an actuator for an actively adjustable roll stabilizer according to the preamble of claim 1. The invention further relates to an actively adjustable roll stabilizer for a motor vehicle according to claim 13.

[0002] Actuators for actively adjustable roll stabilizers are known from the prior art. In this context, reference is made to patent disclosure DE 10 2013 202 258 A1, which describes an actuator with features of the preamble of claim 1. As essential elements, this actuator comprises a drive unit and a drive-connected gearbox, which is designed as a multi-stage planetary gearbox with several interconnected planetary gear stages and can be connected on the output side to a stabilizer section of the roll stabilizer.Within the actuator, a drive speed provided by the drive unit (e.g., an electric motor) is reduced – in a manner known in itself – via several planetary gear stages to a significantly lower output speed. This allows a stabilizer section of a roll stabilizer, connected to the actuator on the output side, to rotate around an axis. The reduction provided by the multi-stage planetary gear ensures that a considerably higher torque is applied on the output side (at the stabilizer section) than at the drive unit.

[0003] When installed on an adjustable roll stabilizer, the actuator allows the stabilizer section connected to the actuator on the output side to be rotated around a rotational axis relative to a stabilizer section mounted on the opposite side of the actuator housing. The stabilizer sections can each be coupled at their ends to a wheel suspension of a vehicle equipped with the actively adjustable roll stabilizer. By actuating the actuator and thus rotating the stabilizer sections relative to each other, the vehicle's roll behavior can be influenced. For example, body roll caused by cornering can be counteracted. In addition, body roll caused by uneven road surfaces can be reduced. Vehicle stability and ride comfort are thereby increased.

[0004] A three-stage planetary gearbox, as described in DE 10 2013 202 258 A1, is structurally integrated into a single housing that accommodates the three planetary gear stages in a coaxial arrangement. During the actuator's operation, specifically when the drive unit and the gearbox connected to it are running, the different planetary gear stages exhibit significantly different speeds (rotational speeds) and forces or torques due to the stepwise reduction. At the output-side, third stage of the gearbox, relatively high forces or torques are present at a relatively low rotational speed. Particularly during a change of direction (reversal of the drive unit's direction of rotation), disruptive reversing noises occur in the third planetary gear stage, partly due to backlash. These noises are caused by a direction-change impulse (teeth striking).To mitigate or avoid such switching noises, the use of tensionable planetary gears within a planetary gear stage is known; in this context, reference is made, for example, to DE 10 2017 208 800 B3.

[0005] For the general technical background of the present invention, reference is made to the following prior art documents: DE 10 2015 003 047 A1, US 2018 / 0 291 984 A1 and KR 10 2017 0 121 521 A.

[0006] It is an object of the present invention to provide an alternative or supplementary measure for noise minimization for an actuator as described above. Furthermore, an actively adjustable roll stabilizer for a motor vehicle is to be provided, with which corresponding effects can be achieved.

[0007] The aforementioned problem is initially solved by an actuator for an actively adjustable roll stabilizer according to the features of claim 1. This actuator comprises a drive unit and a drive-connected gearbox, which is designed as a multi-stage planetary gearbox with several interconnected planetary gear stages and can be connected on the output side to a stabilizer section of the roll stabilizer. According to the invention, the actuator is characterized in that the tooth engagement areas of one of the planetary gear stages are located within a gearbox chamber, which is sealed from other areas of the gearbox and is filled to a considerable extent with a lubricant to dampen operational vibrations.

[0008] In this context, the term "tooth engagement areas" of a planetary gear stage refers to areas where gear elements of this stage, such as the sun gear, ring gear, and planet gears, mesh with each other for power transmission; in other words, where they are in meshing tooth engagement. These are areas where the tooth flanks of different gear elements collide and where noise is generated, particularly, but not exclusively, due to changes in direction.

[0009] According to the invention, the tooth engagement areas are located within a gear chamber that is sealed off from other areas of the gearbox. Accordingly, the gear chamber forms a space within the gearbox, which can be designed in various ways, but which accommodates the tooth engagement areas of one of the planetary gear stages, is sealed off from other areas of the gearbox, and is filled to a significant extent with a lubricant to dampen operational vibrations. By filling the gear chamber to a significant extent with a lubricant, in particular a grease with a suitable viscosity, it is ensured that the tooth engagement areas of the planetary gear stage located in the gear chamber are virtually continuously exposed to the lubricant, thereby achieving a noise-reducing damping effect in addition to the lubrication effect.Within a multi-stage, particularly three-stage, planetary gear unit of an actuator as described above, significantly higher rotational speeds occur in the first and second planetary gear stages. These speeds preclude the high lubricant fill level proposed for the preferably third planetary gear stage, as otherwise the lubricant (grease) would foam, particularly in the first planetary gear stage, leading to high friction due to the strong lubricant circulation caused by the high rotational speeds.

[0010] In the actuator proposed according to the invention, the solution is to assign a gearbox chamber sealed off from other areas of the gearbox to one of the planetary gear stages, which advantageously allows for a significantly higher lubricant filling for the respective planetary gear stage – in order to achieve a desired lubrication and damping effect – thereby achieving acoustic advantages.

[0011] Advantageously, a planetary gear stage comprises a sun gear, a ring gear, and planet gears mounted on a planet carrier, which mesh with the sun gear and the ring gear. According to a known, advantageous embodiment, the ring gear is immobile, in particular fixed to the housing.

[0012] Accordingly, either the actuator and / or the actuator's gearbox has a housing that accommodates the multiple planetary gear stages, particularly in a coaxial arrangement with respect to a rotational axis.

[0013] As previously described, the lowest rotational speeds occur on the output-side planetary gear stage, while at the same time the highest forces and torques are present there. Accordingly, an advantageous embodiment of the actuator provides that the sealed gear chamber provided according to the invention is assigned to a preferably output-side planetary gear stage, which operates within the gearbox in the comparatively lowest speed range. This ensures that, due to the high lubricant fill on this planetary gear stage, significantly more flexing work is generated within the grease lubricant despite the low rotational speed or limited rotation angle (in operational use, the output-side planet carrier is rotated by no more than 20°), which is acoustically advantageous due to significant damping effects, particularly during flank changes at zero crossing.Changes in direction within the gearbox. However, a correspondingly high lubricant fill on the first or second planetary gear stage would be a significant disadvantage due to the high rotational speeds present there, resulting in foaming effects and consequently higher friction.

[0014] As already explained, the sealed gear chamber proposed according to the invention can be designed in different ways. According to a structurally preferred embodiment, the sealed gear chamber is a ring-shaped space extending between the sun gear, ring gear, and planet carrier, through which the planet gears, which are mounted on bolts, in particular, penetrate. In addition to the aforementioned gear elements, the gear chamber is spatially delimited by a seal, which will be described in more detail later.

[0015] A preferred embodiment of the actuator provides that the sealed gearbox chamber has a volume that is at least half, but less than completely, filled with lubricant. It has been shown that such a filling level results in a significant damping effect (viscous damping) within the gearbox. Complete filling, on the other hand, is considered impractical.

[0016] The actuator is advantageously characterized by a seal comprising a multitude of sealing elements that prevents the lubricant located in the gearbox chamber from escaping. Different types of sealing elements can be used.

[0017] Advantageously, an annular seal is arranged between the planet carrier and the ring gear and / or between the planet carrier and the housing. Furthermore, an annular seal is advantageously assigned to a bearing of the planet carrier. A seal is also advantageously arranged between the sun gear and the planet carrier.

[0018] The partial sealing of the gearbox proposed according to the invention, and thus the partially increased filling with lubricant in the sealed gearbox chamber, can in itself be used as a measure for noise reduction. In addition, it is also advantageously conceivable as a supplementary noise-reducing measure. Accordingly, at least one of the planet gears in the actuator can advantageously be constructed in two parts, comprising a first and a second partial gear that can be preloaded against each other. For a more detailed description of the construction of such a two-part planet gear, reference is made to the aforementioned DE 10 2017 208 800 B3, which describes such a gear. For sealing purposes, a seal, particularly one acting axially, can be arranged between the partial gears in this case.

[0019] The aforementioned problem is further solved by an actively adjustable roll stabilizer for a motor vehicle according to the features of claim 13. This comprises two stabilizer sections, each of which can be coupled at its end to a wheel suspension of the motor vehicle, and which can be rotated relative to each other about an axis of rotation by means of an actuator as described above, in order to influence the roll behavior of the motor vehicle.

[0020] The invention is explained and described in more detail below with reference to the accompanying drawing. Further advantageous effects of the invention also become apparent from this. The drawing shows: Fig. 1 an actively adjustable roll stabilizer for a motor vehicle with coupled wheel suspensions in a simplified schematic representation from a rear oblique view, Fig. 2 a part of an actuator in half-section, relating to the multi-stage planetary gear contained therein.

[0021] Fig. Figure 1 shows a schematically simplified representation of an actively adjustable roll stabilizer 1 with coupled wheel suspensions. A motor vehicle (not shown here) can be equipped with such an actively adjustable roll stabilizer on a front axle and / or a rear axle, thereby actively influencing the body roll behavior of the motor vehicle.

[0022] The actively adjustable roll stabilizer 1 comprises, as its essential elements, an actuator 2, shown here essentially as a cylindrical unit, which extends along an axis of rotation 4 and has a housing 3. The actively adjustable roll stabilizer 1 also includes a left stabilizer section 5a, which is rigidly connected to the housing 3 of the actuator 2. Furthermore, the actively adjustable roll stabilizer 1 includes a right stabilizer section 5b, which is connected to the actuator 2 on the output side. The arrangement consisting of the left stabilizer section 5a, the right stabilizer section 5b, and the actuator 2 positioned between them forms a C-shaped torsion spring in a manner known per se, whereby, by operating the actuator 2, the right stabilizer section 5b can be rotated about the axis of rotation 4 relative to the left stabilizer section 5a.

[0023] The left stabilizer section 5a and the right stabilizer section 5b are each coupled at their ends, i.e., at their ends furthest from the actuator 2, to a left wheel suspension 6a and a right wheel suspension 6b, respectively, each of which rotatably holds a left wheel 7a and a right wheel 7b, respectively. In the (not shown in detail here) installed state of the actively adjustable roll stabilizer 1, including the wheel suspensions, on a motor vehicle, the roll behavior of the vehicle body can be actively influenced by actuating the actuator 2 in a manner known per se.

[0024] Fig. Figure 2 shows a section of an actuator 2 according to the invention for an actively adjustable roll stabilizer. The axis of rotation 4 of the substantially rotationally symmetric actuator 2 forms the axis of symmetry. In accordance with the core of the present invention, the illustration includes Fig. 2 essentially a gearbox constructed as a multi-stage planetary gearbox, which is housed within the housing 3 of the actuator 2, in addition to a drive unit 8 indicated here only by the reference numeral 8.

[0025] The in Fig. Actuator 2, partially shown and explained in more detail below, can be part of an actively adjustable roll stabilizer 1, as shown by Fig. 1 explained.

[0026] Out of Fig. Figure 2 shows that the actuator 2 extends along a rotational axis 4 and has a substantially rotationally symmetrical structure. Within the housing 3 of the actuator 2 are a drive unit 8 (indicated only by a reference numeral) in the form of an electric drive motor and a multi-stage planetary gearbox with several interconnected planetary gear stages 10, 20, 30 in a coaxial arrangement.

[0027] The dotted lines perpendicular to the axis of rotation 4 indicate that the drive motor 8 initially drives a sun gear 11 of the first planetary gear stage 10. A second planetary gear stage 20 is driven by the first planetary gear stage 10 and in turn drives an output-side third planetary gear stage 30, which is connected on the output side to the right stabilizer section of a roll stabilizer indicated by reference numeral 5b (not shown in detail in the drawing). Fig. 1) is connectable. For rotatable mounting and absorption of forces, a planet carrier 33 located on the output side of the third planetary gear stage 30 is rotatably mounted relative to the housing 3 about the axis of rotation 4 by means of a rolling bearing 9 in the form of a double angular contact ball bearing.

[0028] In a manner known in isolation, each of the three planetary gear stages 10, 20, 30 comprises a sun gear 11, 21, 31, a ring gear 15, 25, 35 fixed to the housing, and planet gears 12, 22, 32 mounted on a planet carrier 13, 23, 33. The planet gears 12, 22, 32 are each rotatably mounted relative to the respective planet carrier 13, 23, 33 by means of a bolt 14, 24, 34 and interposed rolling bearings (not specified here) and are in meshing engagement with, on the one hand, the sun gear 11, 21, 31 and, on the other hand, the ring gear 15, 25, 35 of the respective planetary gear stage 10, 20, 30.

[0029] The three-stage planetary gear shown ensures that an input speed provided by the drive motor 8 is reduced at the sun gear 11 via three planetary gear stages to a significantly lower speed of the output-side planet carrier 33.

[0030] At the in Fig. In the actuator 2 shown, the planet gear 32 on the third planetary gear stage 30 is designed – in a manner known per se – as a split gear, comprising a first partial gear 32a and a second partial gear 32b, arranged axially adjacent to one another and preloaded against each other by an intervening spring element 32c in a manner known per se (compare DE 10 2017 208 800 B3). The preloading of the partial gears 32a and 32b against each other helps to reduce backlash within the gearbox of the actuator 2, which can lead to disturbing operating noises, particularly during changes of direction within the gearbox.

[0031] Actuator 2 according to Fig.According to the invention, 2 comprises a further measure (in principle independent of the previously described split gear) that contributes to minimizing the noise of the transmission. Accordingly, the tooth engagement areas of the third planetary gear stage 30 are located within a gear chamber 38, which is sealed from other areas of the transmission and is filled to a considerable extent with a lubricant 36 to dampen operating-related vibrations.

[0032] The gear chamber 38 on the third planetary gear stage 30 is a ring-shaped space extending between the sun gear 31, ring gear 35, and planet carrier 33, through which the planet gears 32, mounted on bolts 34, penetrate. A seal 37, comprising a plurality of sealing elements 37a, 37b, 37c, 37d, 37e, ensures that the ring-shaped gear chamber 38 (interrupted by planet gears 32) is sealed to the outside, specifically against the second planetary gear stage 20 and the first planetary gear stage 10, and on the output side, particularly against the bearing 9.

[0033] Accordingly, the sealed gear chamber 38 has a defined volume. To achieve the effect according to the invention, this volume is largely filled with a lubricant 36 in the form of grease of suitable viscosity. This results in sufficient flexing within the lubricant at the gear meshing areas of the third planetary gear stage 30, particularly between the sun gear 31, planet gears 32, and ring gear 35, despite relatively low rotational speed. This ensures not only adequate lubrication but also significant noise-reducing damping. In particular, during changes of direction within the gearbox, flank-change shocks are significantly reduced, resulting in considerably fewer disturbances within the gearbox. For this purpose, the volume of the gear chamber 38 is at least half, but less than completely, filled with the lubricant.

[0034] The seal provided for the gearbox chamber 38 at the third planetary gear stage 30 allows the remaining areas of the gearbox, in particular the first planetary gear stage 10 and / or the second planetary gear stage 20, to be filled with lubricant to a significantly different extent, especially to a significantly smaller volume fraction. Due to the considerably higher rotational speeds occurring there, a lubricant fill of more than half in the first and / or second planetary gear stage 10 or 20 would be associated with considerable disadvantages due to foaming. The seal according to the invention also allows a different type of lubricant to be used on the first and / or second planetary gear stage 10 or 20, thus advantageously meeting different requirements in the various gearbox areas.

[0035] The seal 37 of the gearbox chamber 38 prevents the lubricant 36 contained in the gearbox chamber 38 from escaping. For this purpose, the seal 37 comprises a seal 37a or 37e arranged between the sun gear 31 and the planet carrier 33. Furthermore, an annular seal 37b is arranged between the planet carrier 33 and the ring gear 35. To prevent lubricant from escaping on the output side, an annular seal 37d is also assigned to the bearing 9 of the planet carrier 33. Reference sign 1 (active) adjustable roll stabilizer 2 Actuator 3 cases 4 Rotation axis 5a left stabilizer section 5b right stabilizer section 6a left wheel suspension 6b right wheel suspension 7a left wheel 7b right wheel 8 Drive motor 9 warehouses 10 first planetary gear stage 11 Sun wheel 12 planetary gear 13 planetary carriers 14 bolts 15 Ring gear (housing-mounted) 20 second planetary gear stage 21 Sun wheel 22 planetary gear 23 planetary carriers 24 bolts 25 Ring gear (housing-mounted) 30 third planetary gear stage 31 Sun wheel 32 planetary gear 32a first partial gear 32b second partial gear 32c spring element 33 planetary carriers 34 bolts 35 Ring gear (housing-mounted) 36 Fat 37 Sealing 37a-e Sealing element 38 volumes

Claims

[1] Actuator (2) for an actively adjustable roll stabilizer (1), comprising a drive unit (8) and a drive-connected gearbox, which is designed as a multi-stage planetary gearbox with several interconnected planetary gear stages (10, 20, 30) and can be connected on the output side to a stabilizer section (5b) of the roll stabilizer (1), characterized by , that the tooth engagement areas of one of the planetary gear stages (30) are located within a gear chamber (38) which is sealed against other areas (10, 20) of the gear and is filled to a considerable extent with a lubricant (36) to dampen operating vibrations. [2] Actuator according to claim 1, characterized by, that each planetary gear stage (10, 20, 30) has a sun gear (11, 21, 31), a ring gear (15, 25, 35) and planet gears (12, 22, 32) mounted on a planet carrier (13, 23, 33), which are in meshing engagement with the sun gear (11, 21, 31) and the ring gear (15, 25, 35). [3] Actuator according to claim 1 or 2, characterized by , that its gearbox is designed as a three-stage planetary gearbox. [4] Actuator according to any of the preceding claims, characterized by , that the actuator (2) and / or the gearbox has a housing (3) which accommodates the several planetary gear stages (10, 20, 30) in a coaxial arrangement with respect to a rotational axis (4). [5] Actuator according to any of the preceding claims, characterized by , that the sealed transmission chamber (38) is assigned to a preferably output-side planetary gear stage (30) which is operated within the transmission in the comparatively lowest speed range. [6] Actuator according to any one of claims 2 to 5, characterized by , that the sealed gearbox chamber (38) is a ring-shaped space extending between the sun gear (31), ring gear (35) and planet carrier (33), which is penetrated by the planet gears (32) which are mounted in particular on bolts (34). [7] Actuator according to any of the preceding claims, characterized by , that the sealed gearbox chamber (38) has a volume that is at least half but less than completely filled with the lubricant (36). [8] Actuator according to any of the preceding claims, characterized by a seal (37) comprising a plurality of sealing elements (37a, 37b, 37c, 37d, 37e) which prevents the lubricant (36) located in the gearbox chamber (38) from escaping. [9] Actuator according to any one of claims 2 to 8, characterized by, that an annular seal (37b, 37d) is arranged between planet carrier (33) and ring gear (35) and / or between planet carrier (33) and housing (3). [10] Actuator according to any one of claims 2 to 9, characterized by , that a ring-shaped seal (37d) is associated with a bearing (9) of the planet carrier (33). [11] Actuator according to any one of claims 2 to 10, characterized by , that a seal (37a, 37e) is arranged between the sun wheel (31) and the planet carrier (33). [12] Actuator according to any one of claims 2 to 11, characterized by , that at least one of the planet gears (32) is constructed in two parts and comprises a first and a second partial gear (32a, 32b), wherein a seal (37c) acting in particular axial direction is arranged between the partial gears (32a, 32b). [13] Actively adjustable roll stabilizer (1) for a motor vehicle, comprising two stabilizer sections (5a, 5b) which can be coupled at their ends to a wheel suspension (6a, 6b) of the motor vehicle and which can be rotated relative to each other about an axis of rotation (4) by means of an actuator (2) according to one of claims 1 to 12 in order to influence the roll behavior of the motor vehicle.

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