CN117006195A

CN117006195A - Torsional vibration damper with gears

Info

Publication number: CN117006195A
Application number: CN202310364502.1A
Authority: CN
Inventors: 乌尔班·潘瑟
Original assignee: Schaeffler Technologies AG and Co KG
Current assignee: Schaeffler Technologies AG and Co KG
Priority date: 2022-05-05
Filing date: 2023-04-07
Publication date: 2023-11-07
Also published as: DE102022111145A1

Abstract

The torsional vibration damper (1) proposed here comprises an input part (2) and an output part (3) which can be torsionally limited relative to one another about a rotational axis (A) against the action of at least one spring element (5). With respect to the rotation axis (A), the input part (2) is arranged on a first side of the output part (3), and the gear carrier (10) together with the gear (11) is arranged on a second side opposite to the first side of the output part (3). The gear (11) has helical teeth. If torque is transmitted from the shaft (4) via the input part (2), the spring element (5), the output part (3), the carrier (10) and the gear wheel (11), for example, to the internal combustion engine, the resulting axial forces are supported on the axial bearings (14). Since its bearing radius (21) is larger than the force radius (22) of the gear wheel (11), no tilting moment is generated, since the corresponding axial reaction forces (23, 24) are larger than the corresponding axial forces (17).

Description

Torsional vibration damper with gears

Technical Field

The invention relates to a torsional vibration damper with a connected gear, which is preferably used in a starter generator in a drive train of a motor vehicle.

Background

In reciprocating piston engines, the periodic process of accelerated piston motion and gas forces in the intake, compression, work and exhaust, in combination with the firing order of the individual cylinders, causes rotational non-uniformities in the crankshaft and the flywheel mass connected in the form of a flywheel. Since the torque and stiffness of the rotating components of the drive train are a torsional vibration-capable structure with a characteristic natural frequency, rotational irregularities introduced by the engine can force torsional vibrations that can cause undesired side effects such as acoustic anomalies or increased wear of the components without damping. To reduce the effect, torsional vibration dampers are used.

From the prior art, a torsional vibration damper is known, which is provided for compensating in particular torsional vibrations in the drive train of a motor vehicle in order not to transfer torsional vibrations generated by an internal combustion engine to the transmission, so that the service life of the transmission is increased. Corresponding torsional vibration dampers are known, for example, from US 2020/0032853 A1. In order to compensate for the corresponding torsional vibrations, the rotating flywheel masses are each mounted on both the engine side and the transmission side. The flywheel masses are arranged coaxially and torsionally with respect to one another and are mounted torsionally limited with respect to one another about the rotational axis of the torsional vibration damper against the action of the spring element. The spring element and the flywheel mass together form a torsional vibration damper designed as a dual-mass flywheel.

By dividing the flywheel mass on the input side on the engine side and the flywheel mass on the output side on the transmission side, the moment of inertia of the rotating transmission component is increased. By targeted coordination of the spring elements, the resonant frequency of the torsional vibration damper is displaced significantly below the idle speed of the engine and the excited engine arrangement. Thereby, torque decoupling of the internal combustion engine from the powertrain occurs.

In particular when used in a starter generator, the torsional vibration damper must be operated in different operating conditions, including on the one hand the operating conditions for starting the internal combustion engine and on the other hand the operating conditions for operating the starter generator as a generator. The two operating conditions differ in the direction in which torque is transmitted through the torsional vibration damper and in the magnitude of the transmitted torque. The two operating situations require different bearing concepts in order to support the moments that occur. This is costly.

Disclosure of Invention

The present invention is based on the object of at least partially overcoming the problems known from the prior art.

The object is achieved by means of the features of the torsional vibration damper of the invention. Further advantageous embodiments of the invention are described herein. The features listed individually in the examples can be combined with one another in a technically meaningful way and can define further embodiments of the invention. Furthermore, the features of the invention are explained and illustrated in detail in the description, wherein further preferred embodiments of the invention are shown.

A torsional vibration damper according to the invention is proposed, comprising an input part, an output part and at least one spring element, wherein the input part and the output part can be torsionally limited relative to one another about a rotational axis against the action of the at least one spring element, wherein the carrier is connected in a rotationally fixed manner with the output part together with a toothed wheel having helical teeth, wherein the toothed wheel and the input part are formed on opposite sides of the output part. The torsional vibration damper is characterized in that the axial bearing for the output part is formed at the input part at a bearing radius with respect to the rotational axis and is larger than the force radius of the gear wheel, wherein the force radius is the radius at which the force is transmitted between the gear wheel and the further gear wheel, wherein a radial bearing is formed, which is formed radially inside the gear carrier.

Unless explicitly stated otherwise, terms such as radius, radial direction, axial direction, circumferential, and circumferential direction used in this document always refer to axes of rotation.

Torsional vibration dampers are used in particular in starter generators, which can be understood as a motor vehicle Generator (Lichtmaschine) or a combination of a Generator (Generator) for charging a battery and a starter for starting an internal combustion engine. In this case, depending on the operating situation, torque is transmitted from the input part to the output part and thus to the gear wheel, in particular if a connection to the internal combustion engine is made via the gear wheel and the internal combustion engine has to be started. In this case, high torques occur. In the second operating situation, torque is transmitted from the internal combustion engine via the gear and the output member to the input member and via said input member to the shaft of the starter generator. This is the generator operation, in which case the starter generator operates as a generator for charging the battery. The torque transmitted is small and has a different sign than the torque in the first operating state.

By using a gear with helical teeth, an axial force component, i.e. an axial force, is generated during operation, which axial force has to be absorbed by the bearing. The term "force radius" is understood to mean the radius with respect to the axis of rotation at which a force is introduced into the gear or from the gear into the meshed gear. The force radius is in particular the maximum radius at which the gears that are engaged are in contact when engaged. The force radius is smaller than a bearing radius of the axial bearing at which the output member is supported in the axial direction.

If, now, for example, when starting the internal combustion engine, axial forces are introduced into the output part from the direction of the gear wheel, a larger bearing radius causes a supporting force on the axial bearing which is oriented opposite to the axial forces and which is not only in the region of the introduction of the following forces but also in the region offset by exactly 180 ° about the axis of rotation: the force is introduced into a region corresponding to the region in which the gear wheel meshes with another gear wheel via which the aforementioned gear wheel is connected with the internal combustion engine. In this operating situation, therefore, no tilting moment acts on the gearwheel and the carrier. Forces caused by tangential and radial forces can be absorbed by the radial bearing.

In the second operating condition, the sign of the torque differs from in the first operating condition, the corresponding axial force acting from the direction of the output member towards the direction of the gear. The axial bearing cannot absorb the corresponding forces, but the radial bearing, which is located radially completely inside the carrier and the gear, supports a tilting moment which, due to the smaller amount, is significantly smaller than in the first operating situation.

The axial bearing is thus configured such that it can absorb the axial forces caused by the introduction of torque into the output member via the gear, while the axial forces caused by the introduction of said torque from the output member into the gear are supported in the radial bearing.

Preferably, the radial bearing is configured such that it protrudes out of the gear in both directions in relation to the axis of rotation in the axial direction. Since the radial bearing protrudes out of the gearwheel and the carrier in both directions in the axial direction, by means of forces which can be introduced by the gearwheel in the radial direction and in the tangential direction, tilting moments caused by said forces can be excluded.

Preferably, the outer radius of the gear is less than or equal to the bearing radius. Because the force radius is smaller than the outer radius of the gear, the force transmission does not take place at the outer radius but in the meshed teeth. Measuring the bearing radius as a function of the outer radius of the gear wheel thus allows the size of the torsional vibration damper to be determined, which always causes a corresponding absorption of axial forces when a torque is introduced into the gear wheel from the input part via the output part.

Preferably, the input member is connected in a rotationally fixed manner to the shaft, and the radial bearing is supported on the shaft. This is preferably the shaft of the starter generator. The transmission of torque between the shaft and the input part as the primary-side damping element can be realized in a simple manner in terms of design and at the same time allows the support of the radial bearing on the shaft. The shaft and the input element are particularly preferably formed in one piece. This simplifies the installation of the torsional vibration damper.

According to a further aspect of the invention, a starter generator is proposed, which comprises a shaft and a torsional vibration damper as described hereinabove, in which the shaft is connected in a rotationally fixed manner to an input part and a radial bearing is supported on the shaft. The input member is preferably formed integrally with the shaft.

In a starter generator, a direct or indirect connection to an internal combustion engine is established via a gear in such a way that: the gears are in meshing engagement with the starting ring gear or ensure torque flow via one or more gears connected therebetween. Starter generators are used in particular in motor vehicles, preferably motorcycles or automobiles, and combine the function of the starter of an internal combustion engine together with the starter of an automobile generator. The details and advantages described for the torsional vibration damper can be transferred and applied to the starter generator and vice versa.

It is to be noted in advance that the terms used herein ("first", "second") are used to distinguish one or more objects, sizes or procedures of the same type, i.e. in particular not necessarily to define the relatedness and/or order of the objects, sizes or procedures to each other. If correlation and/or order is desired, this is explicitly stated herein or will be apparent to those skilled in the art upon examination of the specifically described designs.

Drawings

The invention and the technical field are described in detail below with reference to the accompanying drawings. It should be noted that the invention should not be limited by the illustrated embodiments. In particular, if not explicitly stated otherwise, it is also possible to extract some aspects of the facts set forth in the figures and to combine them with other components and knowledge in the present description and/or in the figures. It should be noted in particular that the figures and the dimensional relationships particularly shown are merely schematic. Like reference numerals refer to like objects so that the description from other figures may be used in addition as necessary. The drawings show:

FIG. 1 shows a longitudinal section through a torsional vibration damper;

fig. 2 shows a longitudinal section through a torsional vibration damper in a first operating situation;

fig. 3 shows a longitudinal section through a torsional vibration damper in a second operating situation; and

fig. 4 shows a schematic view of a starter generator with a torsional vibration damper.

Detailed Description

Fig. 1 shows a torsional vibration damper 1 with an input part 2 and an output part 3. The input member 2 and the output member 3 can be twisted relative to each other about the axis of rotation a against the action of the at least one spring element 5. The present embodiment comprises two spring elements 5. The input member 2 is in this example formed integrally with a shaft 4 which is rotatable about an axis of rotation a. Unless explicitly disclosed otherwise, the terms radial, radial direction, axial direction, circumferential direction and tangential are always understood herein to relate to the axis of rotation a.

The cover 6 is connected to the input part 2 in a rotationally fixed manner, said cover and the input part 2 together forming a channel 7 in which at least one spring element 5, preferably comprising at least one curved pressure spring, is accommodated and guided. The spring element 5 is in this case in the circumferential direction at a first side against a stop 8 of the input part 2 and at a second side opposite the first side against a stop 9 of the output part 3.

The carrier 10 is connected in a rotationally fixed manner to the output part 3. The toothed wheel 11 with helical teeth is connected to the gear carrier 10 in a rotationally fixed manner via a screw 12. The gear 11 has a plurality of teeth 13.

The output member 3 is axially supported at the input member 2 via an axial bearing 14. The gear carrier 10 is at least partially formed radially inside the gear 11 and is supported on the shaft 4 via a radial bearing 15 formed radially inside the gear carrier 11. Via the snap ring 16, the gear carrier 10, and thus the gear 11 and the output member 3, are also fixed against displacement in the axial direction, i.e. in the direction of the rotation axis a.

The torsional vibration damper 1 is preferably mounted as part of a starter generator which combines the function of a starter for an internal combustion engine with the function of a motor vehicle generator. In this case, the shaft 4 is the shaft of a starter generator. The starter generator is directly or indirectly connected to the internal combustion engine via a gear wheel 11 with helical teeth. By using the torsional vibration damper 1 at the starter generator, very different operating conditions are possible. Fig. 2 shows a first operating situation with an applied high torque for starting the internal combustion engine via the gear 11, while fig. 3 shows a second operating situation with an applied lower torque of opposite sign in generator operation for generating electrical energy.

Fig. 2 shows the operation when starting the internal combustion engine. In this case, torque is transmitted from the shaft 4 of the starter generator via the input part 2, the spring element 5, the output part 3 and the gear carrier 10 to the gear 11 and via said gear to a further gear connected to the internal combustion engine in meshing engagement. The necessary torque, the sign of which is defined here as positive for better differentiation from the second operating situation (fig. 3), is significantly higher in magnitude than in the second operating situation and is, for example, 100Nm newton meters.

In this operating situation, a first axial force 17 in the negative x-direction (see the coordinate system shown), a first radial force 18 in the negative y-direction and a first tangential force 19 directed outwards from the plane of the drawing are acting on the gearwheel 11 due to the helical toothing. The radial bearing 15 is formed entirely in the radial direction within the carrier 10 and the gear 11. Thus, the first radial force 18 and the first tangential force 19 are supported via the radial bearing 15 (see the first radial reaction force 20). The first radial force 18 and the first tangential force 19 cause a tilting moment acting on the radial bearing 15. The first axial force 17 causes a tilting moment which is absorbed in the axial bearing 14, however, because the bearing radius 21 of the axial bearing 14 with respect to the axis of rotation a is greater than the force radius 22, the supporting forces generated in the axial bearing 14 (only the first supporting force 23 at the angular position, in which the effect of the first axial force 17 is shown by way of example, and the second supporting force 24 at the angular position, in which it is rotated 180 °) are positive, wherein the first supporting force 23 is greater than the second supporting force 24, so that the tilting moment is absorbed and the carrier 10, and thus the radial bearing 15, is not tilted.

Fig. 3 shows an alternative second operating situation in which the respective starter generator is operated in generator operation. In this case, torque is transmitted from the internal combustion engine via the gear 11, the gear carrier 10, the output part 3, the spring element 5 and the input part 2 to the shaft 4 of the starter generator. The torque is significantly smaller in magnitude than in the first operating state, and has the opposite sign compared to the first operating state. For example, the torque is about 13Nm in magnitude when the generator is running.

Thus, due to the helical teeth, a second axial force 25 directed in the positive x-direction (see the coordinate system shown), a second radial force 26 directed in the negative y-direction and a second tangential force 27 directed in the plane of the drawing are exerted on the gear wheel 11. The radial bearing 15 is configured such that the entire gear 11 protrudes from the radial bearing 15 on both sides in the axial direction, so that the second radial force 26 and the second tangential force 27 always act within the length of the radial bearing 15, so that no tilting moment can be generated. The second axial force 25 is significantly smaller in magnitude than the first axial force 17 compared to the first operating condition. Radial bearing radius 30 of radial bearing 15 is less than force radius 22. By the opposite direction of the second axial force 25 compared to the first axial force 17, a tilting moment is generated which is not absorbed via the axial bearing 14. However, the small tilting moment is absorbed by the radial bearing 15 via the reaction force pair constituted by the first radial reaction force 28 and the second radial reaction force 29, so that the radial bearing 15 can support the tilting moment.

Fig. 4 very schematically shows a starter generator 31 with a shaft 4 which is connected, on the one hand, to a starter generator base part 32 comprising the remaining parts of the starter generator 31 and, on the other hand, to the input part 2 of the torsional vibration damper 1 as described above.

The torsional vibration damper 1 proposed here comprises an input part 2 and an output part 3 which can be torsionally limited relative to one another about a rotational axis a against the action of at least one spring element 5. With respect to the rotation axis a, the input member 2 is arranged on a first side of the output member 3, and the carrier 10 together with the gear 11 is arranged on a second side opposite to the first side of the output member 3. The gear 11 has helical teeth. If torque is transmitted from the shaft 4 via the input member 2, the at least one spring element 5, the output member 3, the carrier 10 and the gear 11 to, for example, an internal combustion engine, the resulting axial forces are supported on the axial bearings 14. Because its bearing radius 21 is greater than the force radius 22 of the gear 11, no tilting moment is generated, because the corresponding axial reaction forces 23, 24 are greater than the corresponding axial forces 17.

List of reference numerals:

1. torsional vibration damper

2. Input member

3. Output part

4. Shaft

5. Spring element

6. Cover for a container

7. Channel

8. Stop block

9. Stop block

10. Gear carrier

11. Gear wheel

12. Bolt

13. Teeth

14. Axial bearing

15. Radial bearing

16. Clasp ring

17. First axial force

18. First radial force

19. First tangential force

20. First radial reaction force

21. Bearing radius

22. Radius of force

23. First supporting force

24. Second supporting force

25. Second axial force

26. Second radial force

27. Second tangential force

28. First radial reaction force

29. Second radial reaction force

30. Radial bearing radius

31. Starter generator

32. Basic component of starter generator

Arotation axis

Claims

1. A torsional vibration damper (1), the torsional vibration damper comprising: an input part (2), an output part (3) and at least one spring element (5), wherein the input part (2) and the output part (3) can be twisted around a rotational axis (A) in a limited manner against the action of the at least one spring element (5), wherein a gear carrier (10) is connected in a rotationally fixed manner to the output part (3) together with a gear (11) having an oblique toothing, wherein the gear (11) and the input part (2) are formed on opposite sides of the output part (3), characterized in that an axial bearing (14) for the output part (3) is formed at the input part (2) at a bearing radius (21) relative to the rotational axis (A), and the bearing radius (21) is greater than a force radius (22) of the gear (11), wherein the force radius (22) is a radius at which force is transmitted between the gear (11) and a further gear, wherein a radial bearing (15) is formed, which is formed at the radial inside the gear carrier (10).

2. Torsional vibration damper (1) according to claim 1,

wherein the radial bearing (15) is designed such that it protrudes beyond the gearwheel (11) in both directions in relation to the axis of rotation (A) in the axial direction.

3. Torsional vibration damper (1) according to one of the preceding claims,

wherein the outer radius of the gear (10) is smaller than or equal to the bearing radius (21).

4. Torsional vibration damper (1) according to one of the preceding claims,

wherein the input part (2) is connected to the shaft (4) in a rotationally fixed manner and the radial bearing (15) is supported on the shaft (4).

5. Torsional vibration damper (1) according to claim 4,

wherein the input element (2) and the shaft (4) are formed in one piece.

6. Starter generator (31) comprising a shaft (4) and a torsional vibration damper (1) according to any of the preceding claims, wherein the shaft (4) is connected in torsion with the input part (2) and the radial bearing (15) is supported on the shaft (4).

7. Starter generator (31) according to claim 6, wherein the input member (2) is formed in one piece with the shaft (4).