Drivetrain for a motor vehicle, and motor vehicle

Abstract

The invention relates to a drivetrain for a motor vehicle, comprising a drive machine (10), a transmission (12) and a housing in which the drive machine (10) and the transmission (12) are arranged, wherein: at least one shaft (14, 16) of the drive machine (10) or of the transmission (12), which shaft is rotatable about an axis of rotation extending in the axial direction (A), is mounted on the housing by means of a bearing (24); a vibration damper (28) designed for damping vibrations of the shaft (14, 16) is held on the shaft (14, 16) via a holding region (30) of the vibration damper (28); the holding region (30) of the vibration damper (28) at most has a spacing from the bearing (24) in the axial direction which corresponds to 20 percent of an axial length (A) of the shaft (14, 16).

Description

[0001] Powertrain for a motor vehicle as well as motor vehicle

[0002] The invention relates to a drive train for a motor vehicle and a motor vehicle.

[0003] From EP 0 988470 B1, a hollow drive shaft with an integrated vibration damper is known. This vibration damper consists of a damping mass and an elastic coupling element. The damping mass is rotationally and axially symmetric and is operatively connected to the inner wall of the hollow drive shaft via the elastic coupling element. The elastic coupling element is made of an elastomeric material.

[0004] Furthermore, an arrangement for vibration damping of a hollow component is known from DE 36 32 418 A1. The arrangement comprises a damping mass located inside the cavity and bearing against its inner wall, which is elastically mounted in the cavity.

[0005] Furthermore, a vibration damper for a propeller shaft is known from JP-H-08233 031 A.

[0006] The object of the present invention is to provide a solution by which rigid body vibrations of shafts of a drive train of a motor vehicle can be dampened particularly well.

[0007] 24-2163 ABZ EXA 24.09.2024 This problem is solved according to the invention by the subject matter of the independent claims. Further possible embodiments of the invention are disclosed in the dependent claims, the description, and the figures. Features, advantages, and possible embodiments set forth in the description for one of the subject matter of the independent claims are to be regarded, at least analogously, as features, advantages, and possible embodiments of the respective subject matter of the other independent claims, as well as of any possible combination of the subject matter of the independent claims, optionally in conjunction with one or more of the dependent claims.

[0008] The invention relates to a drivetrain for a motor vehicle, in particular a car, and especially a passenger car. The drivetrain is configured to propel the motor vehicle. The drivetrain comprises a drive engine, a transmission, and a housing in which the drive engine and the transmission are arranged. The drive engine is configured to provide torque by which the motor vehicle can be propelled by transmitting the torque provided by the drive engine to the wheels of the motor vehicle. The transmission is configured to increase the torque provided by the drive engine and to make this increased torque available for driving the wheels.The drive train is designed so that at least one shaft of the drive motor or the gearbox, which is rotatable about an axially extending axis of rotation, is supported on the housing by means of a bearing. This means that the drive motor comprises at least one shaft and the gearbox comprises at least one, and in particular several, shafts, with at least one of these shafts being supported on the housing by means of a bearing. It is possible that all shafts of the gearbox and the drive motor are supported on the housing by means of their respective bearings.

[0009] The drive train is designed to incorporate a vibration damper, intended to dampen shaft vibrations, which is held in place by a retaining section. The vibration damper comprises the retaining section, at least one spring section, and at least one mass section. The retaining section is designed to be attached to the shaft, thus holding the vibration damper in place.

[0010] 24-2163 ABZ EXA 24.09.2024 Drivetrain is also held. The mass is held to the mounting area via the spring section, allowing it to oscillate relative to the mounting area for vibration damping. This means that the oscillating mass is attached to the mounting area via the spring section, which enables the mass to oscillate relative to the mounting area. In the drivetrain, the mounting area of ​​the vibration damper is designed so that its axial distance from the bearing is at most 20% of the axial length of the shaft. In other words, the vibration damper is held particularly close to the bearing on the shaft via the mounting area, allowing rigid body vibrations of this shaft to be dampened particularly efficiently. Rigid body vibration of the shaft is defined as the shaft oscillating without deformation.In this type of rigid body vibration, the entire shaft oscillates within the bearing. By attaching the vibration damper to the shaft via its mounting area in the immediate vicinity of the bearing, and thus at a distance from the bearing that is at most 20% of the axial length of the shaft, such rigid body vibrations of this shaft can be particularly well damped and thus eliminated.

[0011] In a possible further development of the invention, the mounting area of ​​the vibration damper is arranged to overlap the bearing in a radial direction perpendicular to the axial direction. In other words, the mounting area of ​​the vibration damper and the bearing overlap each other in the radial direction. The vibration damper is thus attached to the shaft with its mounting area particularly close to the bearing by which the shaft is supported in the housing. This allows rigid body vibrations of this shaft to be damped or eliminated particularly efficiently very close to the bearing.

[0012] In a further possible embodiment of the invention, the shaft is designed as a hollow shaft and the vibration damper is arranged inside the shaft. In this embodiment, it is particularly possible that the vibration damper is held by the mounting area on a wall of the shaft that defines a cavity within the hollow shaft. The arrangement of the vibration damper within the cavity of the hollow shaft enables a particularly compact and space-saving design of the drive train.

[0013] 24-2163 ABZ EXA 24.09.2024 In a further possible embodiment of the invention, the vibration damper is configured to dampen rigid body vibrations. The vibration damper is particularly well suited for damping rigid body vibrations if it has a damping mass with a particularly high weight. For this purpose, the damping mass can be provided by a material with a particularly high density. Furthermore, a vibration damper can be selected that is configured to dampen vibrations with a frequency of 1.1 kHz. This allows rigid body vibrations of the shaft to be damped particularly strongly, and in particular completely eliminated, by means of the vibration damper.

[0014] In a further possible embodiment of the invention, the vibration damper comprises the spring section adjoining the holding section and the mass section, which is indirectly held to the holding section via the spring section. The mass section is designed to dampen shaft vibrations by oscillating in a radial direction perpendicular to the axial direction relative to the holding section. This means that the vibration damper is designed as a radial damper. Thus, the mass section of the vibration damper can oscillate radially to compensate for the shaft vibrations.

[0015] In this context, it is particularly possible for the spring section to comprise an elastomer and / or a metal. Designing the spring section with an elastomer allows for elastic deformation, thereby enabling the mass to oscillate relative to the holding area. Alternatively or additionally, the spring section can comprise the metal, in particular a thin-walled metal element. This metal acts as a spring and allows the mass to oscillate relative to the holding area. Designing the spring section with metal ensures a particularly long service life for the vibration damper.

[0016] In another possible embodiment of the invention, the vibration damper is designed in a pin-like shape, and the retaining area is located at one end of the vibration damper, so that the vibration damper is held at one end on the shaft. In other words, the vibration damper is designed in a rod-like shape, wherein

[0017] 24-2163 ABZ EXA 24.09.2024 This rod-shaped vibration damper is held at one end via the mounting area on the shaft, and the free end of the rod-shaped vibration damper can oscillate relative to the mounting area for vibration damping of the shaft, particularly in the radial direction. Especially when the vibration damper is arranged within the cavity of the hollow shaft, the rod-shaped design of the vibration damper allows the use of a particularly large damping mass by designing the vibration damper with a particularly large length, in particular with a particularly large axial length of the mass area.

[0018] In another possible embodiment of the invention, the drive machine is an electric traction machine. The traction machine can also be referred to as an electric motor. The traction machine is designed to power the vehicle using electrical energy from the vehicle's battery. If the drive machine is designed as an electric traction machine, then the drive train is an electric drive train of the vehicle. The vibration damper effectively dampens vibrations of the shaft of the electric drive train, allowing the electric drive train to operate with particularly low vibration and, consequently, very quietly.Furthermore, due to the particularly low vibrations, the bearing by which the shaft is mounted on the housing is subjected to very little mechanical stress during operation, resulting in a particularly long service life for the drive train.

[0019] In another possible embodiment of the invention, the shaft is a transmission intermediate shaft. The transmission intermediate shaft is a shaft of the transmission configured to transmit torque from a transmission input shaft, driven directly by the engine, to a transmission output shaft. The transmission output shaft is configured to drive at least one wheel of the vehicle. The particularly effective damping of vibrations, especially the rigid body vibrations of the transmission intermediate shaft, allows the torque to be transmitted from the input shaft to the transmission output shaft with exceptionally low losses, thereby enabling particularly efficient operation of the transmission and, consequently, the drivetrain.

[0020] 24-2163 ABZ EXA 24.09.2024 The invention further relates to a motor vehicle with a drivetrain as already described in connection with the drivetrain according to the invention, wherein the motor vehicle can be driven by means of the drivetrain. The drivetrain is in particular an electric drivetrain by means of which the motor vehicle can be driven electrically.

[0021] Further features of the invention may become apparent from the claims, the figures, and the description of the figures. The features and combinations of features mentioned above in the description, as well as the features and combinations of features shown below in the description of the figures and / or in the figures themselves, can be used not only in the combinations specified, but also in other combinations or on their own, without departing from the scope of the invention.

[0022] The drawing shows in:

[0023] Fig. 1 shows a schematic perspective view of a drive motor and a gearbox of a drive train for a motor vehicle;

[0024] Fig. 2 shows a partially cutaway side view of the drive machine as well as a drive shaft and a transmission intermediate shaft;

[0025] Fig. 3 shows a schematic top view of an internal damper; and

[0026] Fig. 4 shows a schematic partially cutaway view of the intermediate shaft of the transmission, in which a vibration damper is arranged in a cavity enclosed by the intermediate shaft.

[0027] In the figures, identical and functionally equivalent elements are provided with the same reference symbols.

[0028] Figure 1 shows a drive motor 10, in this case an electric drive motor, and a gearbox 12 of a drive train, in this case an electric drive train of a motor vehicle. In addition to the drive motor 10 and the gearbox 12, the drive train comprises a housing (not shown in the figures) in which the drive motor 10 and the gearbox 12 are accommodated.

[0029] 24-2163 ABZ EXA 24.09.2024. The drive machine 10 comprises a rotor shaft 14, and the gearbox 12 comprises several gearbox shafts 16. In this design, a drive shaft 18 of the gearbox 12 is formed integrally with the rotor shaft 14, or rather, is formed as an extension of the rotor shaft 14. In addition to the drive shaft 18, the gearbox 12 comprises an intermediate gearbox shaft 20 and an output shaft 22. As can be seen particularly well in Fig. 1, the drive shaft 18 is meshed with the intermediate gearbox shaft 20 via a gear, thereby forming a first gear ratio stage, and the intermediate gearbox shaft 20 is meshed with the output shaft 22 via another gear, thereby forming a second gear ratio stage of the gearbox 12. Fig. 2 shows the drive machine 10, the drive shaft 18 and the intermediate shaft 20 of the gearbox 12 in a partially cutaway view.Here, the gears 26 can be identified, via which the drive shaft 18 forms the toothing with the intermediate transmission shaft 20.

[0030] In this design, at least one of the shafts 14, 16 is rotatably mounted on the housing about an axis of rotation by means of at least one bearing 24. The respective shafts 14, 16 of the drive train can exhibit rigid body vibrations during operation. The transmission shafts 16 in the drive train can exhibit rigid body vibrations due to large load variations of the drive machine 10 and numerous interactions. This means that the respective transmission shaft 16 behaves as a rigid body and thus vibrates as a whole in its bearings 24 while the transmission shaft 16 is driven by a gear.

[0031] To effectively dampen, and in particular eliminate, such rigid body vibrations of shafts 14, 16 of the drive train, especially the intermediate shaft 20 of the transmission 12, a vibration damper 28 is used. Possible embodiments of the vibration damper 28 are shown in Figures 3 and 4. The vibration damper 28 comprises a holding section 30, a spring section 32 adjoining the holding section 30, and a mass section 34 adjoining the spring section 32. The mass section 34 comprises a damping mass of the vibration damper 28, which can dampen vibrations of the respective shaft 14, 16 by means of vibrations relative to the holding section 30, in particular radial vibrations relative to the holding section 30. In Figure 4, the spring section 32 is indicated only by a dashed line. It may be provided that

[0032] 24-2163 ABZ EXA 24.09.2024 the spring area 32 comprises an elastomer and / or a metal, for example a thin-walled metal element.

[0033] To ensure that rigid body vibrations of at least one of the shafts 14, 16, in particular the intermediate transmission shaft 20, are particularly well damped, the vibration damper 28 is held on this shaft 14, 16 via the mounting area 30. The mounting area 30 of the vibration damper 28 has a maximum axial distance to the nearest bearing 24 that corresponds to 20% of the axial length of the shaft 14, 16. Here, only the distance between the mounting area 30 of the vibration damper 28 and the bearing 24 supporting the shaft 14, 16, whose vibrations are to be dampened by the vibration damper 28, is considered. The axial direction of each shaft 14, 16 runs parallel to the longitudinal direction of a rotational axis about which the respective shaft 14, 16 rotates during operation.Here, the vibration damper 28 is arranged particularly close to the bearing 24 in the axial direction for damping rigid body vibrations. For this purpose, the holding area 30 of the vibration damper 28 is designed to have a maximum axial distance to the nearest bearing by which this shaft 14, 16 is supported on the housing, which corresponds to 20% of the axial length of this shaft 14, 16.

[0034] In particular, the mounting area 30 of the vibration damper 28 can be arranged on the shaft 14, 16 such that it radially overlaps the bearing 24 supporting this shaft 14, 16. In this respect, the mounting area 30 of the vibration damper 28 has no axial distance to the bearing 24 due to the radial overlap. To effectively dampen rigid body vibrations, the vibration damper 28 can be designed to have a particularly high damping mass. In this case, the vibration damper 28 is designed as a radial damper. This means that the mass area 34 can oscillate in the radial direction perpendicular to the axial direction A relative to the mounting area 30, thereby damping the vibrations of the shaft 14, 16 on which this vibration damper 28 is mounted.To enable a particularly compact design of the drive machine 10, the vibration damper 28 is designed as an internal damper and is thus arranged in a cavity of the shaft 14, 16 to be damped. (With others.)

[0035] 24-2163 ABZ EXA 24.09.2024 In words, the respective shaft 14, 16 to be damped is designed as a hollow shaft and the vibration damper 28 is arranged in the cavity enclosed by this hollow shaft.

[0036] A possible embodiment of the vibration damper 28 is shown in a schematic side view in Fig. 3. The vibration damper 28 can be rotationally symmetrical. The retaining region 30 can be annular, as shown in Fig. 3, and configured so that its outer wall, which radially defines the vibration damper 28, rests against the shaft 14, 16 to be damped, in particular against an inner wall of the shaft 14, 16 that defines the cavity of the shaft 14, 16. With respect to the radial direction R, the vibration damper 28 can, as shown in Fig. 3, have the mass region 34, which is enclosed radially outward by both the spring region 32 and the retaining region 30. It is possible that the mass region 34 is also enclosed radially outward by the spring region 32.

[0037] The vibration damper 28 can be designed in the form of a pin or rod, as shown in Fig. 4. Fig. 4 shows a schematic, partially cutaway view of the vibration damper 28 arranged in a cavity of the intermediate shaft 20 of the transmission. The retaining area 30 of the vibration damper 28 is radially covered outwards by the bearing 24, which is indicated in Fig. 4 only by dashed lines. The spring area 32, which is indicated in Fig. 4 by a dashed line, adjoins the retaining area 30. In the embodiment shown in Fig. 4, the spring area 32 of the vibration damper 28 is also rod-shaped, with the retaining area 30 adjoining the spring area 32 at one end and the mass area 34 adjoining the spring area 32 at the other end. The vibration damper 28 is also designed in a rod shape in the mass area 34 in the embodiment shown in Fig. 4.The overall pin- or rod-shaped vibration damper 28, in the embodiment shown in Fig. 4, is thus held at one end by the retaining area 30 on the inner wall of the intermediate transmission shaft 20, which defines the cavity, and has a free end at the other end, which can oscillate radially to dampen vibrations of the intermediate transmission shaft 20. The damping frequency of the vibration damper 28 shown in Fig. 4 can be adjusted by modifying the respective radii R1 and R2 of the vibration damper 28 as well as the respective axial extensions of the respective length sections Y of the vibration damper 28, which have a uniform radius.

[0038] 24-2163 ABZ EXA 24.09.2024 the damping of the rigid body vibrations of the intermediate shaft 20 of the transmission can keep structure-borne noise of the first gear stage, especially in the range of 1,100 Hz, particularly low.

[0039] The rigid body vibrations of the shafts 14, 16 of the drive train exhibit a high load dependency and are influenced by numerous interactions within the overall drive train system. Because the transmission shafts 16 behave as rigid bodies, a high-frequency bending frequency of the transmission shafts 16 results, particularly outside of an excitable range.

[0040] The vibration damper 28 has 4 length segments of different radii in its mass area 34. By selecting an axial length for each of these length segments and corresponding radii for the mass area 34 within each length segment, the damping frequency of the vibration damper 28 can be set with particular precision.

[0041] Overall, the invention shows how the elimination of rigid body vibration in transmission shafts 16 of an electric drive train of a motor vehicle can be implemented.

[0042] 24-2163 ABZ EXA 24.09.2024 Reference List

[0043] 10 electric drive motor 12 gearbox 14 rotor shaft

[0044] 16 Transmission shaft 18 Transmission input shaft 20 Transmission intermediate shaft

[0045] 22 Gearbox output shaft 24 Bearing 26 Gear

[0046] 28 Vibration damper 30 Holding area 32 Spring area

[0047] 34 Mass range

[0048] A axial direction

[0049] R radial direction R1 , R2 respective radii Y1 length range of the vibration damper

[0050] 24-2163 ABZ EXA 24.09.2024

Claims

Patent claims 1. Drive train for a motor vehicle, comprising a drive motor (10), a transmission (12) and a housing in which the drive motor (10) and the transmission (12) are arranged, wherein at least one shaft (14, 16) of the drive motor (10) or the transmission (12) rotatable about an axis of rotation extending in the axial direction (A) is supported on the housing by means of a bearing (24), wherein a vibration damper (28) designed to dampen vibrations of the shaft (14, 16) is held on the shaft (14, 16) by means of a retaining area (30) of the vibration damper (28), wherein the retaining area (30) of the vibration damper (28) has a distance to the bearing (24) in the axial direction (A) that corresponds to 20 percent of an axial length (A) of the shaft (14, 16).

2. Drive train according to claim 1, characterized in that the holding area (30) of the vibration damper (28) is arranged to cover the bearing (24) in a radial direction (R) perpendicular to the axial direction (A).

3. Drive train according to claim 1 or 2, characterized in that the shaft (14, 16) is designed as a hollow shaft and the vibration damper (28) is arranged inside the shaft (14, 16).

4. Drive train according to one of the preceding claims, characterized in that the vibration damper (28) is configured to dampen rigid body vibrations.

5. Drive train according to one of the preceding claims, characterized in that the vibration damper (28) has a section adjoining the holding area (30). 24-2163 ABZ EXA 24.09.2024 The spring area (32) and a mass area (34) are included, which is indirectly held on the holding area (30) via the spring area (32) and which is designed to dampen vibrations of the shaft (14, 16) by oscillating in a radial direction (R) perpendicular to the axial direction (A) relative to the holding area (30).

6. Drive train according to claim 5, characterized in that the spring area (32) comprises an elastomer and / or a metal.

7. Drive train according to one of the preceding claims, characterized in that the vibration damper (28) is designed in a pin shape and the holding area (30) is located at one end of the vibration damper (28), so that the vibration damper (28) is held at one end on the shaft (14, 16).

8. Drive train according to one of the preceding claims, characterized in that the drive machine (10) is an electric traction machine.

9. Drive train according to one of the preceding claims, characterized in that the shaft (14, 16) is an intermediate transmission shaft (20) of the transmission (12).

10. Motor vehicle with a drive train according to one of the preceding claims, by means of which the motor vehicle can be driven. 24-2163 ABZ EXA 24.09.2024

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