Abstract
A roll stabilizer, e.g., for a multitrack motor vehicle, with a divided torsion bar, between the mutually facing ends of which an actuator is arranged for transmission of a torsion moment. The actuator may have a housing which is connected to the one torsion bar part and houses a motor and a planetary gear mechanism connected to the motor, the gear output of which is connected to the other torsion bar part. and the planet wheels of which intermesh with a mating gear. A multistage planetary gear mechanism is provided, whose final planetary gear stage on the gear output side is equipped with planet wheels, wherein at least one of said planet wheels is divided into two axially adjacent spur gears which are rotatable relative to each other and between which a torsion spring is actively arranged. The divided planet wheel may be in play-free engagement with the mating gear.
Claims
1. A roll stabilizer for a multitrack motor vehicle, comprising: a divided torsion bar having mutually facing ends, between which an actuator is arranged for transmission of a torsion moment, wherein the actuator has a housing which is connected to one torsion bar part and houses a motor and a planetary gear mechanism connected to the motor, a gear output of which is connected to the other torsion bar part and planet wheels of which intermesh with a mating gear, wherein a multistage planetary gear mechanism is provided, whose final planetary gear stage on a gear output side is equipped with planet wheels, wherein at least one of said planet wheels is divided into two axially adjacent spur gears which are rotatable relative to each other and between which a torsion spring is actively arranged, such that a divided planet wheel is in play-free engagement with the mating gear.
2. The roll stabilizer as claimed in claim 1, wherein the torsion spring transmits a torsion moment between the two spur gears, under which torsion moment, when the roll stabilizer is load-free, firstly a tooth of one spur gear lies against a tooth of the mating gear delimiting a tooth gap, and secondly a tooth of the other spur gear lies against another tooth of the mating gear delimiting the tooth gap.
3. The roll stabilizer as claimed in claim 1, wherein the mating gear is formed by a ring gear connected rotationally fixedly to the housing.
4. The roll stabilizer as claimed in claim 1, wherein the planet wheels are mounted rotatably in a planet carrier and are all configured as divided planet wheels.
5. The roll stabilizer as claimed in claim 1, wherein the torsion spring is formed as a circular ring segment and has two peripheral spring ends, between which a slot is formed in which two cams engage which are each assigned to one of the two spur gears, wherein one cam is assigned to one of the two spring ends and the other cam is assigned to the other spring end.
6. The roll stabilizer as claimed in claim 5, wherein the two cams are arranged at least substantially without overlap in an axial direction.
7. The roll stabilizer as claimed in claim 6, wherein the two cams are arranged axially behind each other when the torsion spring is without load.
8. The roll stabilizer as claimed in claim 1, wherein the spur gears of a common planet wheel are mounted rotatably on a common bearing bolt.
9. The roll stabilizer as claimed in claim 5, wherein the two spur gears are identical in structure and wherein the two cams are each connected integrally to the assigned spur gear.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0028] FIG. 1 shows an active roll stabilizer according to an embodiment of the disclosure,
[0029] FIG. 2 shows a planetary gear stage of the active roll stabilizer from FIG. 1,
[0030] FIG. 3 shows a cross-section through the planetary gear stage of FIG. 2,
[0031] FIG. 4 shows a partial longitudinal section through the planetary gear stage of FIG. 2,
[0032] FIG. 5 shows a planet wheel as depicted in FIG. 4,
[0033] FIG. 6 shows a front view of the planet wheel from FIG. 5,
[0034] FIG. 7 shows the planet wheel from FIG. 5 in an exploded view,
[0035] FIG. 8 shows a perspective view of the planet wheel from FIG. 5 in cross-section,
[0036] FIG. 9 shows an exploded view of the planet wheel as in FIG. 8,
[0037] FIG. 10 shows a section along line X-X from FIG. 5,
[0038] FIG. 11 shows a torsion spring of the planet wheel from FIG. 5,
[0039] FIG. 12 shows the torsion spring from FIG. 11 in perspective view, and
[0040] FIG. 13 shows a diagram with the pretension moment of the planet wheel over the twist angle.
DETAILED DESCRIPTION
[0041] FIG. 1 shows an active roll stabilizer for a multitrack motor vehicle which has a torsion bar 3 divided into two torsion bar parts 1, 2, and an actuator 4 actively arranged between the two torsion bar parts 1, 2. This active roll stabilizer is arranged transversely to the vehicle longitudinal axis; its free ends are connected to wheel carriers (not shown). The actuator 4 has a hollow cylindrical housing 5 which houses an electric drive (not shown) and a planetary gear mechanism connected to the drive and not shown in detail. The housing 5 is connected rotationally fixedly to the torsion bar part 2. An output shaft (not shown) of the planetary gear mechanism is connected rotationally fixedly to the torsion bar part 1. When the actuator is activated, the two torsion bar parts 1, 2 are twisted relative to each other and a torsion moment is built up.
[0042] FIG. 2 shows a planetary gear stage 6 of said planetary gear mechanism. A planet wheel carrier 7 carries four gear wheels 8 which are distributed over the periphery and will be described in more detail below, and which are here used as planet wheels 9. The further description of the gear wheels 8 according to the disclosure is given with reference to these planet wheels 9.
[0043] FIG. 3 shows in cross-section the planetary gear stage 6 fitted in the housing 5. The planet wheels 9 with teeth 23 intermesh with teeth 24 of a mating gear 25, which is here formed as a ring gear 10 of the planetary gear mechanism and connected rotationally fixedly to the housing 5.
[0044] FIG. 4 shows a planet wheel 9 in longitudinal section. The planet wheel 9 has two axially adjacent spur gears 11 which, in the exemplary embodiment shown, are identical in structure. The two spur gears 11 are arranged rotatably on a bearing bolt 12 which is attached to the planet wheel carrier 7. The gear wheel may be asymmetric, so that one half is configured narrower. The cams may themselves also be asymmetric in both the peripheral direction and in their axial installation length.
[0045] FIG. 5 shows the planet wheel 8 with its individual parts. On their outer periphery, the spur gears 11 have teeth 13 for engagement with the ring gear and with the sun wheel. A torsion spring 14 in the form of a circular ring segment is arranged between the two spur gears 11 and will be described in more detail below. The two spur gears 11 are provided with plain bearing bushes 15 for rotatable mounting on the bearing bolt. A thrust washer 16 is attached to each of the end faces of the spur gears 11 facing away from each other. Two axially adjacent teeth 13 of the two spur gears 11 together form one of the teeth 23 of the planet wheel 9.
[0046] The thrust washers in the gear wheels according to the disclosure may be omitted depending on application.
[0047] It can also be seen from FIG. 5 that the torsion spring 14 has an inner diameter which extends to the outer periphery of the bearing bolt (not shown here). The outer diameter of the torsion spring extends almost up to the tip circle diameter of the ring gear but does not collide with the teeth of the ring gear.
[0048] FIG. 6 shows the two spur gears 11 in a rotational position with the teeth 13 arranged offset. An initial twist i between the two spur gears 11 is clearly evident. In the rotational position depicted, no pretension has yet been applied to the torsion spring 14; when the two spur gears 11 rotate further in the direction towards a rotational position in which the teeth 13 of the two spur gears 11 align, there is however an increase in a torque as the load of the torsion spring increases, up to a maximum moment Tmax with the teeth 13 axially aligned.
[0049] FIG. 7 clearly shows the individual parts of the planet wheel 9. Here it is evident that the spur gears 11 on the two mutually facing ends are each provided with an axially protruding cam 17 which is connected integrally to the assigned spur gear 11. The figure clearly shows the torsion spring 14, between the two peripherally opposing ends of which a slot 18 is formed in which the two cams 17 engage. The mutually facing ends of the two spur gears have bearing faces 19 for axial mounting of the torsion spring 14.
[0050] FIGS. 8 and 9 clearly show the engagement of the cams 17 in the slot 18 of the torsion spring 14. FIG. 8 in particular clearly shows that the two cams 17, between the bearing face 19 of the assigned spur gear 11 and the free cam end of this cam 17, jointly have an axial extension which is smaller than the axial extension of the torsion spring 14. If the torsion spring 14 is arranged axially play-free between the two spur gears 11, an axial distance is formed between the two cams 17, i.e. the cams 17 do not touch.
[0051] FIG. 9 clearly shows that the torsion spring 14 has an approximately rectangular cross-sectional profile which is arranged in the manner of an arc around the rotation axis of the planet wheel 9, wherein the torsion spring 14 is formed flat. The spring ends 20 of the torsion spring 14 have mutually facing contact faces 21 for the cams 17. The axial extension of these contact faces 21 corresponds to the axial thickness of the torsion spring 14.
[0052] Both contact faces 21 each overlap both cams 17 in the axial direction. The two cams 17 are arranged substantially axially aligned for mounting of the torsion spring 14. Depending on the design of the cams, a pretension of the torsion spring 14 can be set in both directions of rotation. The extension of the two cams 17 in the peripheral direction is slightly smaller than the extension of the slot 18 of the unloaded torsion spring 14. Consequently, assembly of the planet wheel 9 is simple. The peripheral play of the two cams 17 in the slot is dimensioned such that the spur gears 11 can twist relative to each other by an angle which is smaller than half the pitch of the spur gear.
[0053] In FIG. 8, the designations A and B indicate the contacts which exist between the torsion spring 14 and the two cams 17 when the torsion spring 14 is pretensioned. The two contact faces 21 formed at the spring ends 20 are loaded diagonally; in position A, the one cam 17 is in contact, and in position B, the other cam 17.
[0054] FIG. 10 shows a section through the planet wheel 9. This depiction shows that the force transmission between the cams 17 and the torsion spring 14 takes place on the radially outer portion of the torsion spring 14. The further radially outward the force transmission takes place, the stiffer the torsion spring 14 behaves and the more favorable the influence of the torsion spring 14 on reducing the disruptive rattling noise on a load change. Since the torsion spring 14 in deformed state is no longer perfectly circular, the contact point will drift radially outward, which benefits the stiffness of the torsion spring.
[0055] FIG. 11 shows the opening angle alpha between the two contact faces 21 of the torsion spring 14. The contact faces 21 enclosing the opening angle alpha evidently lie in a plane which contains the rotation axis of the gear wheel 8. In this position of the contact faces 21, the maximum possible force can be transmitted in the peripheral direction with a minimum possible radial force component.
[0056] The contact faces 21 extend over a height h which extends radially in a region as far radially out as possible at the spring end 20. In the exemplary embodiment, this region lies in a portion which amounts to between 80% and 100% of the outer diameter of the torsion spring 14. The further the attack point of the force is spaced radially from the rotation axis of the planet wheel 9, the better the torsion spring 14 can transmit the torque.
[0057] FIG. 12 shows the torsion spring in perspective view.
[0058] For the installation and function of the gear wheel according to the disclosure as a planet wheel in the planetary gear mechanism, reference is made to FIG. 13 which shows a torque loading of the torsion spring 14 over the twist angle between the two spur gears 11.
[0059] The initial twist i of the two spur gears 11 (FIG. 6) represents the twist angle before these are joined to the ring gear and sun wheel. When the planet wheels 9 are joined to the sun wheel and ring gear using the planet carrier 7, the spur gears 11 are twisted relative to each other, since the initial twist i is greater than the toothing play z available between the planet wheel and the ring gear/sun wheel. The spur gears 11 are now twisted relative to each other by the pretension angle v. A pretension moment Tini is set. The gear mechanism is now play-free. The travel still available is the toothing play z. If the gear mechanism is now subjected to a moment, the spur gears twist further relative to each other until the tooth flanks make contact. During this process, the torsion spring is loaded to the maximum moment Tmax. This energy is now stored in the spring and reduces the impulse with which the tooth flanks can impact on each other. This effect is achieved by targeted matching of the spring stiffness and spring travel. The spring travel can be set using the toothing play.
[0060] The teeth 23 of the planet wheels 9 engage in the tooth gaps 25 of the ring gear 10 (FIG. 3). When the planetary gear mechanism is unloaded, firstly the one tooth 13 of the one spur gear 11 lies with pretension on the tooth 24 of the ring gear 10 delimiting the tooth gap 25; secondly, the other tooth 13 of the other spur gear 11 lies on the other tooth 24 of the ring gear 10 delimiting the tooth gap 25. If an operating load is now applied, the two spur gears 11 twist, with an increase in the torque acting between the two spur gears 11, until their teeth 13 are axially aligned and both lie with pretension on a common tooth 24 of the ring gear 10.
[0061] Similarly, the planet wheels 9 engage in the tooth gaps of the sun wheel so that play-free engagement of the planet wheels with the sun wheel is guaranteed.
LIST OF REFERENCE SIGNS
[0062] 1 Torsion rod part [0063] 2 Torsion rod part [0064] 3 Torsion rod [0065] 4 Actuator [0066] 5 Housing [0067] 6 Planetary gear stage [0068] 7 Planet wheel carrier [0069] 8 Gear wheel [0070] 9 Planet wheel [0071] 10 Ring gear [0072] 11 Spur gear [0073] 12 Bearing bolt [0074] 13 Teeth [0075] 14 Torsion spring [0076] 15 Plain bearing bush [0077] 16 Thrust washer [0078] 17 Cam [0079] 18 Slot [0080] 19 Bearing face [0081] 20 Spring end [0082] 21 Contact face [0083] 22 Clearance [0084] 23 Tooth (planet wheel) [0085] 24 Tooth (ring gear) [0086] 25 Tooth gap (ring gear) [0087] 26 Mating gear
