Method for manufacturing a planetary gear stage for a chassis actuator, chassis actuator and roll stabilizer

Abstract

A method for manufacturing a planetary gear stage for a suspension actuator comprises the steps of: providing a ring gear (6a) with internal teeth (1), providing a planet carrier that accommodates a set of planet gears, temporarily partially expanding the ring gear (6a) to deform it from an unloaded state (6a) with a circular cross-section to a stressed state (6a') with a polygonal cross-section, mounting the planet carrier by aligning it so that it can be inserted into the ring gear (6a') using an assembly clearance created by the partial expansion in the axial direction, and releasing the tension on the ring gear (6a'), thereby deforming it back into the state (6a) with a circular cross-section in which the planet carrier is received by the ring gear (6a) with no or at least minimal play.

Description

[0001] The invention relates to a method for manufacturing a planetary gear stage according to claim 1. The invention also relates to a chassis actuator for a motor vehicle according to claim 10, and an actively adjustable roll stabilizer for a motor vehicle according to claim 11.

[0002] Planetary gears are used in various areas of engineering. These are so-called epicyclic gears, meaning they have not only a fixed shaft but also shafts that rotate in a circular path within the housing. In planetary gears, the rotating shafts run parallel to the fixed shaft, with the gears rotating on these shafts (called "planetary gears") orbiting a central gear, the sun gear. There are various applications for planetary gears in automotive engineering.

[0003] To increase vehicle stability and ride comfort, it is common practice to equip vehicles with a so-called roll stabilizer. In its simplest form, this is essentially a C-shaped torsion bar spring, mounted in the middle opposite the vehicle body, with its outer, opposing ends each connected to a wheel suspension. This design ensures that when cornering, the roll stabilizer not only compresses the vehicle body on the outside side (due to centrifugal force), but also slightly lowers the inside wheel (resulting in improved stability).

[0004] To further enhance vehicle stability and ride comfort, it is known from the prior art to design such roll stabilizers to be actively adjustable. The roll stabilizer comprises an actuator and is divided into two stabilizer sections that can be rotated relative to each other about a rotational axis by means of the actuator. By rotating the stabilizer sections relative to each other, a roll movement of the vehicle body is deliberately generated, or a roll movement of the vehicle body caused by external influences is deliberately counteracted. As is known, an electric motor is used for the drive, which is usually coupled to a mechanical transmission, in particular in the form of a multi-stage planetary gear unit, to translate the torque or speed of the electric motor.

[0005] In a well-known manner, such planetary gear sets have a centrally located sun gear, a set of planet gears, and a ring gear at each stage. The planet gears are each rotatably mounted about their own axis of rotation relative to a planet carrier. All planet gears mesh and roll against the centrally located sun gear. Simultaneously, the planet gears mesh and roll against an outer ring gear with internal teeth, which, in the case of an actively adjustable roll stabilizer, is usually fixed to the housing, for example, as an integral part of the landing gear actuator housing or at least attached to it.

[0006] Within the multi-stage planetary gear set of an actively adjustable roll stabilizer, high transmitted torques can occur in certain operating situations. Furthermore, load changes within the planetary gear set can occur in certain operating situations due to a reversal of the direction of rotation. Gear backlash, which may be caused by assembly issues, can lead to undesirable noise generation during such load changes, specifically when a change in tooth flank occurs due to a change in direction within the gear set.

[0007] To avoid or at least reduce backlash within a planetary gear set – and thus to avoid or reduce the resulting acoustic disturbances – DE 10 2017 208 800 B3 proposes a gear for a planetary gear set that is divided into a first spur gear and a second spur gear, which can be preloaded against each other by a spring ring. The gear is used as a planet gear within at least one stage of a planetary gear set and helps to eliminate backlash within the planetary gear stage, thereby reducing noise generation, particularly during changes in the direction of the gear set.

[0008] DE 10 2010 046 958 A1 discloses a low-backlash planetary gear and a roll stabilizer with this planetary gear, wherein the backlash is reduced by an axial preload.

[0009] WO 01 / 92 759 A1 discloses a low-backlash planetary gear in which the ring gear is radially preloaded with the planet gears and is therefore also expanded during operation and has a polygonal shape.

[0010] DE 10 2011 116 427 A1 discloses a low-backlash planetary gear in which the radial preload is applied by the sun gear and which is thus elastically deformed during operation.

[0011] It is an object of the present invention to provide a further measure for improving the acoustic behavior of a planetary gear set for a suspension actuator, which can be used as an alternative or supplement to already known acoustic improvement measures. Accordingly, a method for manufacturing a planetary gear set for a suspension actuator, a suspension actuator for a motor vehicle, and an actively adjustable roll stabilizer for a motor vehicle are to be provided.

[0012] The aforementioned problem is initially solved by a method according to the features of claim 1. According to the invention, this is a method for manufacturing a planetary gear stage for a chassis actuator, comprising the following steps: Providing a ring gear with internal teeth, Providing a planet carrier that accommodates a set of planetary gears, temporary partial widening of the ring gear in order to deform it from an unloaded state with a circular cross-sectional profile to a stressed state with a polygonal cross-sectional profile, The planet carrier is mounted by aligning it in such a way that it can be inserted into the ring gear using an assembly clearance created by partial widening. Relaxation of the ring gear, whereby the ring gear deforms back into the state with a circular cross-sectional profile, in which the planet carrier is received by the ring gear with no or at least minimal play.

[0013] The method according to the invention relates initially to the production of a planetary gear stage for a suspension actuator. Accordingly, it is conceivable that a multi-stage planetary gear used in a suspension actuator comprises only one planetary gear stage produced by the method according to the invention. This may already be sufficient to achieve the effects according to the invention, in particular a noise-reducing reduction of backlash. It was recognized according to the invention that assembly-related backlash within a planetary gear causes disruptive noise, especially during load changes (particularly changes of direction).It was also observed that for the assembly of a planetary gear set, particularly for inserting the planet carrier with the planet gears mounted on it, a certain amount of clearance is necessary between the internal teeth of the ring gear and the engagement areas of the planet gears. This clearance is essential to allow the planet carrier to be inserted axially (relative to the axis of rotation). According to the invention, a method has been developed to ensure sufficient gear clearance for assembly purposes by temporarily and partially expanding the ring gear. In the context of the present invention, partial expansion refers to expansion on individual circumferential sections of the ring gear. Specifically, the expansion does not occur over the entire circumference of the ring gear, but only on selected, suitable circumferential sections.By partially widening the ring gear, it is deformed from an unloaded state with a circular cross-sectional profile to a stressed state with a polygonal cross-sectional profile.

[0014] In the context of the present invention, a polygonal cross-sectional profile is understood to mean a cross-sectional profile resulting from the radial expansion of a deformable ring at individual circumferential sections. In particular, it is understood to mean a cross-sectional profile that deviates even slightly from a circular shape.

[0015] According to the invention, after the partial expansion of the ring gear, the planet carrier is mounted by aligning it so that it can be inserted axially into the ring gear using the assembly clearance created by the partial expansion. The partial expansion of the ring gear thus creates an assembly clearance that allows for easy mounting of the planet carrier.

[0016] After the planet carrier is inserted, the ring gear is released according to the invention, causing it to deform back into shape. This reduces the clearance (temporarily) provided for assembly completely or at least partially. Thus, after carrying out the method according to the invention, and in particular after releasing the ring gear, a planetary gear stage is obtained which – with appropriate dimensioning – can be backlash-free or at least has very tight backlash. Due to the reduced backlash, the planetary gear stage produced in this way causes no noise, or at least significantly reduced noise, even during load changes. The problem mentioned at the outset is thus solved.

[0017] According to an advantageous embodiment of the inventive method, the polygonal cross-sectional profile of the clamped ring gear corresponds to the profile of an outer envelope of the planet carrier with the planet gears mounted thereon. The partial widening of the ring gear is therefore expediently carried out in such a way that the ring gear can accommodate the planet carrier with the planet gears mounted thereon while ensuring a certain amount of assembly clearance.

[0018] Preferably, the number of polygonal expansions of the ring gear corresponds to the number of planet gears in the set of planet gears.

[0019] The temporary partial widening of the ring gear provided for in the invention can be carried out in different ways. According to a preferred embodiment, in the step of temporary partial widening, the ring gear is compressed radially from the outside inwards at individual circumferential sections in order to form widenings at the intermediate circumferential sections. The resulting effect, which is advantageously usable within the scope of the invention, can be explained as follows: by compressing the ring gear radially from the outside inwards at individual circumferential sections – by means of locally applied compressive forces – an elastic deformation takes place at these loaded circumferential sections, in particular they are pressed inwards, deviating from the circular path, and thus deformed (in the sense of an inwards "bulge"). These deformations occur at all circumferential sections that are each subjected to a compressive force.As a consequence of these local inward deformations, the intervening circumferential sections—those not subjected to an inward-directed compressive force—undergo outward elastic deformations (bulging), as the material is forced to yield in this direction. These bulges are thus formed by an outward bulging of the material. As a result, the ring gear, with its alternating inward and outward deformations, exhibits an approximately polygonal cross-sectional shape. The radial compression from the outside to the inside, as described above, offers the advantage of easy accessibility, since the forces required for deformation can be applied directly to the ring gear from the outside.The widening of the intermediate circumferential sections forms as a result of partial compression, without the need to insert a tool into the ring gear. The subsequent assembly, specifically the insertion of the planet carrier into the ring gear, can therefore be carried out easily without any tool obstruction.

[0020] Alternatively or additionally, in the step of temporary partial widening, the ring gear is clamped radially from the inside out at individual circumferential sections in order to form widenings at the circumferential sections.

[0021] In both cases, the ring gear, when under tension, exhibits a cross-sectional profile that would allow for a larger center distance between the planet gears. In reality, the center distance of the planet gears on the planet carrier is constant; accordingly, the deformation of the ring gear provides greater clearance, which can be advantageously used for assembly.

[0022] As already mentioned, in the step of temporary partial expansion, the ring gear is deformed – by applying force radially from the outside and / or from the inside – in order to form expansions. In the context of the present invention, an expansion is to be understood as a deformation deviating from a circular shape outwards, in the sense of an outwardly directed bulge.

[0023] The temporary partial expansion can be carried out in various ways. According to a preferred embodiment of the method, this is done using a multi-part jaw chuck. Preferably, the number of jaws corresponds to the number of planet gears in the set of planet gears.

[0024] To enable the temporary deformation of the ring gear provided for in the invention, the ring gear is expediently made of an elastically deformable material, in particular of metal of a suitable wall thickness.

[0025] The aforementioned problem is further solved by a chassis actuator for a motor vehicle according to the features of claim 10. The chassis actuator according to the invention is provided with a drive train comprising an electric motor, a multi-stage planetary gear unit, and an output element, wherein at least one stage of the planetary gear unit is manufactured according to the previously described method according to the invention. The chassis actuator can advantageously be used with an actively adjustable roll stabilizer.

[0026] The aforementioned problem is also solved by an actively adjustable roll stabilizer for a motor vehicle according to the features of claim 11.

[0027] According to the invention, this comprises a chassis actuator as described above and two stabilizer sections connected thereto, which can be rotated relative to each other about an axis of rotation by means of the chassis actuator in order to influence the rolling behavior of the motor vehicle.

[0028] 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 A schematic view of an actively adjustable roll stabilizer in a simplified perspective representation, Fig. 2 a section of a chassis actuator for an actively adjustable roll stabilizer in partial cross-sectional view, Fig. 3 a planetary gear stage of a chassis actuator in cross-sectional view, Fig. 4 a ring gear in different states, Fig. 5 a ring gear in different states.

[0029] Fig. Figure 1 shows an actively adjustable roll stabilizer 10 in a simplified schematic perspective view from a rear oblique angle. The actively adjustable roll stabilizer 10 can be used on a motor vehicle (not shown here) on one or more axles of the vehicle to influence the roll behavior of the equipped vehicle. According to the illustration of Fig. 1. A left wheel 11a and a right wheel 11b are each articulated to a vehicle body (not shown here for illustrative purposes) via a left wheel suspension 12a and a right wheel suspension 12b, respectively, in a manner known per se. The actively adjustable roll stabilizer 10 comprises as essential elements a chassis actuator 14, which has a substantially cylindrical basic shape and extends along an axis of rotation 7 in the transverse direction of the vehicle when installed on a motor vehicle, as well as an associated left stabilizer section 13a and an associated right stabilizer section 13b.

[0030] At their end furthest from the chassis actuator 14, the left stabilizer section 13a and the right stabilizer section 13b are each coupled to the left wheel suspension 12a and the left wheel 11a or to the right wheel suspension 12b and the right wheel 11b respectively via a so-called pendulum support (not specified here).

[0031] Within a housing 6 of the suspension actuator 14 is a drive train, which will be explained later, consisting of an electric motor, a multi-stage planetary gear, and an output element connected to the right stabilizer section 13b. In a manner known per se, the right stabilizer section 13b can be rotated about the axis of rotation 7 relative to the (housing-fixed) left stabilizer section 13a by means of the suspension actuator 14, in particular by operating the electric motor. Due to the mechanical coupling with the wheel suspensions or the wheels 11a, 11b, the roll behavior of the vehicle body can be influenced in this way.

[0032] To further illustrate the structure of a landing gear actuator, the following is shown. Fig. Figure 2 shows a landing gear actuator 14 in a section view. As can be seen, the landing gear actuator 14 extends essentially rotationally symmetrically with respect to the axis of rotation 7. For orientation, the positions of the left stabilizer section 13a and the right stabilizer section 13b are indicated at least by reference symbols. Also indicated is the position of an electric motor 5, which is arranged within a housing 6 of the landing gear actuator 14 and is connected via a motor shaft 4 to a multi-stage planetary gear unit also arranged within the housing 6.The latter comprises a first planetary gear stage 21, a second planetary gear stage 22, and a third planetary gear stage 23, which are arranged one after the other in an axial direction and are connected to each other in a drive connection to translate a drive speed provided by the electric motor 5 (provided via the motor shaft 4) into an output speed provided on the output side of the third planetary gear stage at the planet carrier 23a. The planet carrier 23a of the third planetary gear stage 23 is connected to an output element 24 via a vibration decoupling element (not specified here), which is rotatably mounted relative to the housing 6 of the landing gear actuator 14 via rolling bearings 15.

[0033] Each of the three planetary gear stages 21, 22, 23 comprises a planet carrier 21a, 22a, 23a, a set of planet gears 21b, 22b, 23b, and a sun gear 21c, 22c, 23c. The planet gears of each of the planetary gear stages 21, 22, 23 mesh with a housing-fixed ring gear. The ring gear is formed by a section of the housing 6 of the landing gear actuator 14. In the first planetary gear stage 21, the ring gear 6b ​​is a section of the housing 6 whose axial width is essentially limited to the first planetary gear stage 21. For the second planetary gear stage 22 and the third planetary gear stage 23, the ring gear is formed by a common housing section, which is referred to here as ring gear 6a.

[0034] Fig. Figure 3 shows a cross-sectional view of a planetary gear stage 31 from the axial direction (relative to the axis of rotation 7), which may be a planetary gear stage within a chassis actuator 14. The illustration shows the presence of a planet carrier 32a, a central sun gear 32c, and a set of four planet gears 32b, wherein the planet gears 32b are each rotatably mounted relative to the planet carrier 32a, at the same distance from the central axis of rotation 7, and with the same center-to-center distance to each other. The in Fig. The planetary gear stage 31 shown in Figure 3 is manufactured according to the inventive method and has virtually no backlash between the ring gear 6a with internal teeth 1 formed on it and the planet gears 32b which are in meshing engagement with it.

[0035] To produce the in Fig. In the planetary gear stage 31 shown in section 3, the ring gear 6a was initially provided. For further explanation, please refer to... Fig. Figure 4 is referenced, which shows, firstly, the ring gear 6a in its unloaded, undeformed state. In this unloaded state, the ring gear 6a has a circular cross-sectional profile.

[0036] According to the inventive method for production, which is described in Fig. In the planetary stage 31 shown, the ring gear 6a is used as shown in the illustration. Fig. 4 temporarily partially expanded. For this purpose, a clamping force 3 is applied to the ring gear at four circumferential regions using a suitable tool, in particular a four-part jaw chuck. This clamping force is directed radially outwards and thus deforms areas of the ring gear in such a way that four polygonal expansions 2 are formed. Accordingly, the expanded ring gear 6a' has a polygonal cross-sectional profile in the clamped state. It should be noted that the illustration according to Fig. Figure 4 shows a greatly exaggerated widening to illustrate the invention. In reality, widenings 2 with a significantly smaller extent, i.e., a significantly smaller deviation from the circular cross-sectional profile of the ring gear 6a in the unloaded state, will suffice to achieve the effect according to the invention. This effect consists in the fact that, in an assembly step following the widening, a planet carrier 32a with the planet gears 32b mounted on it is aligned such that it can be easily inserted axially into the clamped ring gear 6a' by utilizing the assembly clearance created by the widening. The planet carrier 32a is aligned so that the four planet gears 32b each point towards one of the four polygonal widenings 2 in order to benefit from the assembly clearance created by the widening.

[0037] After the planet carrier 32a is inserted into the tensioned ring gear 6a', the ring gear is released, causing it to deform back to state 6a with a circular cross-sectional profile. This deformation occurs in such a way that the planet carrier 32a is in its final assembly state, as shown in Fig. 3 shown, is mounted without play or at least with minimal play within the hollow gear 6a.

[0038] Fig. Figure 5 serves to illustrate a preferred way of carrying out the method according to the invention. It shows – initially comparable to Fig. 4 - a ring gear in different states (unloaded state, tensioned state).

[0039] On the one hand, the ring gear 6a is shown in its unloaded state; on the other hand, the ring gear 6a' is shown in its tensioned state. A significant difference compared to the diagram based on... Fig. The procedure described in section 4 involves partial widening as shown in the illustration. Fig. 5 is caused by applying compressive forces 9 to individual circumferential sections. These compressive forces are directed radially from the outside to the inside (see arrow direction), thus exactly the opposite of the clamping force 3 according to Fig. 4. Through the way in Fig. The compression shown in Figure 5 at the four circumferential sections of the ring gear 6a' forces an expansion at the intervening (also four) circumferential sections, thereby forming the four expansions 2 (the material's deflection forces an outward curvature). The expansions 2 ensure assembly clearance, which facilitates or enables the insertion of a planet carrier. A particularly advantageous aspect of the compression according to Figure 5 is... Fig. Point 5 is that in this case, the force is applied externally. This does not restrict access to the ring gear for mounting the planet carrier.

[0040] The method according to the invention ensures, on the one hand, easy assembly of the planetary gear stage, and on the other hand, backlash-free or at least low-backlash operation of the planetary gear stage, thereby advantageously improving the acoustic behavior during load direction changes. Reference sign 1 Internal toothing 2 polygonal widenings 3 Tension force 4 Motor shaft 5 electric motor 6 cases 6a Ring gear (unloaded state) 6a' Ring gear (tensioned state) 6b Ring gear 7. Axis of rotation 9 Compressive force 10 actively adjustable roll stabilizer 11a; 11b left wheel; right wheel 12a; 12b left wheel suspension; right wheel suspension 13a; 13b left stabilizer section; right stabilizer section 14 Chassis actuator 15 rolling bearings 21 first planetary gear stage 21a Planetary carrier 21b Planetary gear 21c sun wheel 22 second planetary gear stage 22a Planetary carrier 22b Planetary gear 22c sun wheel 23 third planetary gear stage 23a Planetary carrier 23b Planetary gear 23c sun wheel 24 Output element 31 planetary gear stage 32a Planetary carrier 32b Planetary gear 32c sun wheel

Claims

[1] Method for manufacturing a planetary gear stage (21; 22; 23; 31) for a chassis actuator (14), comprising the following steps: Providing a ring gear (6a; 6b) with internal teeth (1), Providing a planet carrier (21a; 22a; 23a; 32a) that accommodates a set of planet gears (21b; 22b; 23b; 32b), temporary partial widening of the ring gear (6a; 6b) in order to deform it from an unloaded state (6a; 6b) with a circular cross-sectional profile into a stressed state (6a') with a polygonal cross-sectional profile, Assembly of the planet carrier (21a; 22a; 23a; 32a) by aligning the planet carrier (21a; 22a; 23a; 32a) in such a way that it can be inserted into the ring gear (6a') using an assembly clearance created by the partial widening in the axial direction, Relaxation of the ring gear (6a'), whereby the ring gear returns to the state (6a) with a circular cross-sectional profile, in which the planet carrier (21a; 22a; 23a; 32a) is received by the ring gear (6a) without play or at least with minimal play. [2] Method according to claim 1, characterized by , that the polygonal cross-sectional profile of the tensioned ring gear (6a') corresponds to the profile of an outer envelope of the planet carrier (32a) with planet gears (32b) mounted on it. [3] Method according to claim 1 or 2, characterized by , that the number of polygonal expansions (2) of the ring gear (6a') corresponds to the number of planet gears (32b) of the set of planet gears. [4] Method according to any of the preceding claims, characterized by , that the ring gear (6a') allows an increased center distance of the planet gears (32b) when under tension. [5] Method according to any of the preceding claims, characterized by, that in the step of temporary partial widening the ring gear (6a, 6b) is compressed radially from the outside inwards (9) at individual circumferential sections in order to form widenings (2) at intermediate circumferential sections. [6] Method according to any of the preceding claims, characterized by , that in the step of temporary partial widening the ring gear (6a; 6b) is radially stretched from the inside out (3) on individual circumferential sections in order to form widenings (2) on the circumferential sections. [7] Method according to any of the preceding claims, characterized by that the temporary partial widening is carried out using a multi-part jaw chuck. [8] Method according to claim 7, characterized by , that the number of jaws corresponds to the number of planet gears (32b) of the set of planet gears. [9] Method according to any of the preceding claims, characterized by, that the ring gear (6a; 6b) is made of an elastically deformable material, in particular of metal of suitable wall thickness. [10] Chassis actuator (14) for a motor vehicle, comprising a drive train comprising an electric motor (5), a multi-stage planetary gear (21, 22, 23) and an output element (24), wherein at least one stage (22; 23) of the planetary gear is manufactured according to a method of the preceding claims. [11] Actively adjustable roll stabilizer (10) for a motor vehicle, comprising a chassis actuator (14) according to claim 10, and two stabilizer sections (13a, 13b) connected thereto, which can be rotated relative to each other about an axis of rotation (7) by means of the chassis actuator (14) in order to influence the roll behavior of the motor vehicle.

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