Damper shaft with a rotation axis for a rotor connection of an electric drive machine

Abstract

The invention relates to a damper shaft (1) with a rotation axis (2) for a rotor connection (3) of an electric drive machine (5,6), comprising at least the following components: - a rotor-side torque connection (7); - a gearbox-side torque connection (8); - a stop device (9) by which a clearance angle (10) between the rotor-side torque connection (7) and the gearbox-side torque connection (8) is predetermined to a maximum angle (11) and only upon reaching the maximum angle (11) are the rotor-side torque connection (7) and the gearbox-side torque connection (8) connected to each other with a second torque stiffness by means of the stop device (9) in a torque-transmitting manner; and - a torsionally flexible connecting device (12), wherein within the clearance angle (10) the rotor-side torque connection (7) and the gearbox-side torque connection (8) are connected to each other with a first torque stiffness by means of the torsionally flexible connecting device (12), where the first torque stiffness is lower than the second torque stiffness. The damper shaft proposed here allows for the reduction of noise emissions caused by zero crossings without affecting the installation space.

Description

[0001] The invention relates to a damper shaft with a rotational axis for a rotor connection of an electric drive motor, a rotor with such a damper shaft for an electric drive motor, a drive train with such a rotor for a motor vehicle, and a motor vehicle with such a drive train.

[0002] Here, a damper shaft is proposed that can be used in a drivetrain with at least one electric drive motor. According to one aspect, a drivetrain with at least one electric drive motor for a motor vehicle is proposed, with a torsional vibration damping unit (e.g., the damper shaft). In a drivetrain with at least one electric (drive) motor for a motor vehicle, i.e., a purely electric drivetrain or a hybrid drivetrain with an additional combustion engine, two NVH-critical phenomena generally occur (NVH: Noise Vibration Harshness).

[0003] Periodic lifting and impact of the tooth flanks of gears or splines due to zero torque crossings leads to gear chattering noises. A single lifting and impact of the tooth flanks of gears or splines due to zero torque crossings leads to clunking noises.

[0004] The acoustic relevance for both types of NVH-critical phenomena increases with the size of the impact masses. This is particularly the case in purely electric and hybrid powertrains due to the transmission-integrated electric (drive) motors with high mass moments of inertia.

[0005] The following measures against gear rattling noises are considered to be known: (1) Tension of the gears in the power flow of the electric (drive) machine due to an increase in the torque of the electric (drive) machine (e.g. charging or boosting). (2) Shifting the NVH-critical operating point towards higher engine speeds. (3) Improvement of the pre-insulation by means of a higher-quality torsional vibration damper (e.g. dual-mass flywheel with centrifugal pendulum absorber instead of a simple dual-mass flywheel) or slip control via a clutch.

[0006] The following measure against clonking noises is considered to be known: (1) Lower torque gradients of the electric (drive) machine at zero torque crossing.

[0007] If NVH-critical phenomena are combatted cost-effectively through software countermeasures, this results in several undesirable side effects on powertrain operation: namely, higher fuel consumption, an impact on battery aging, especially in cold conditions, and reduced longitudinal dynamics. In contrast, conventional hardware solutions are associated with significantly increased manufacturing costs.

[0008] It is therefore an object of the present invention to propose a drive train with at least one electric machine for a motor vehicle which is cost-effective both in production and in operation and in which the NVH behavior is improved.

[0009] Based on this, the present invention is based on the object of at least partially overcoming the disadvantages known from the prior art. The features of the invention are derived from the independent claims, for which advantageous embodiments are presented in the dependent claims. The features of the claims can be combined in any technically reasonable manner, whereby the explanations from the following description as well as features from the figures, which comprise additional embodiments of the invention, can also be consulted for this purpose.

[0010] The invention relates to a damper shaft with a rotational axis for a rotor connection of an electric drive machine, comprising at least the following components: - a rotor-side torque connection; - a torque connection on the gearbox side; - a stop device, by means of which a clearance angle between the rotor-side torque connection and the gearbox-side torque connection is predetermined to a maximum angle and only when the maximum angle is reached are the rotor-side torque connection and the gearbox-side torque connection connected to each other in a torque-transmitting manner by means of the stop device with a second torque stiffness; and - a torsionally soft connecting device, wherein within the clearance angle the rotor-side torque connection and the gearbox-side torque connection are connected to one another in a torque-transmitting manner by means of the torsionally soft connecting device with a first torque stiffness, wherein the first torque stiffness is lower than the second torque stiffness.

[0011] In the following, reference is made to the specified axis of rotation whenever, without explicit indication to the contrary, the axial direction, radial direction, or the direction of rotation and corresponding terms are used. Ordinal numbers used in the preceding and following descriptions serve only to clearly distinguish them and do not reflect the order or ranking of the designated components. An ordinal number greater than one does not necessarily imply that another such component must be present.

[0012] The damper shaft proposed here is a component that, in terms of its functionality, location, and space requirements, is currently unused in a motor vehicle drivetrain. This is also due to the fact that the underlying problem in the context of a drivetrain with at least one electric drive motor—namely, generating a high level of acoustic comfort—was previously unknown. Furthermore, solving this problem while meeting the technical requirements of such a drivetrain is a complex challenge.

[0013] The damper shaft can be used anywhere in the torque flow within a drive train, preferably close to the respective electric drive motor, so that the cause of the noise (namely the torque difference and / or speed difference) is decoupled from the drive train as early as possible. Because shafts are inevitably used in a drive train, a shaft-type damper is ideal, allowing the damper shaft to be used as a replacement for a conventional shaft for a particularly space-saving design. The electric drive motor can be, for example, a radial flux motor or an axial flux motor.

[0014] In one embodiment, the rotor-side torque connection is directly connected to a rotor (or its rotor connection) or, in another embodiment, indirectly (for example via a spur gear, spline connection, or a separating clutch) to a rotor of an electric drive machine (with the separating clutch closed, if applicable) in a torque-resistant manner. In the context presented here, a connection is understood to mean a mechanical connection, which is preferably designed to be as rigid as possible, for example, approximately as a one-piece embodiment, for example by means of a (star or central) screw connection or spline connection. The rotor is formed, for example, exclusively by a rotor or a laminated core or squirrel cage.Alternatively, a rotor connection is additionally formed by means of a shaft, wherein in one embodiment the rotor connection is preferably designed as a hollow shaft on the radial inside and as a solid shaft on the end side (for example as a flange).

[0015] The gearbox-side torque connection is arranged opposite the rotor-side torque connection in the torque flow, i.e., it is connected to the rotor-side torque connection in a torque-transmitting manner exclusively via the torsionally flexible connecting device and the stop device. The gearbox-side torque connection is designed to transmit a torque input into the rotor-side torque connection (of the respective electric drive unit) to the rest of the (connectable) gearbox. However, a reverse torque transmission is at least not excluded and is preferably provided (for example, for generator operation or eddy-current braking, as well as for intermediate operating states).

[0016] For a predetermined clearance angle, for example, a total of 1° [one degree of 360°] up to ± 2°, which thus defines the maximum angle from a neutral angular position (neutral position), a torque with a first torque stiffness is transmitted by means of the torsionally flexible connection device. It should be noted that in one embodiment, the torsionally flexible connection device is the only torque-transmitting connection between the rotor-side torque connection and the gearbox-side torque connection, and thus the first torque stiffness is defined solely by the torsionally flexible connection device. In another embodiment, the torsionally flexible connection device is supported by the stop device (or at least one stop component of the stop device) already within the clearance angle, for example, from the beginning (i.e., already starting from the neutral position).However, an increasing stiffness is provided under relative torsion of the two torque connections, for example due to compression of the respective stop component(s). In one embodiment, the torsionally flexible connecting device is designed for a maximum torque of 20 Nm [twenty Newton meters], preferably 10 Nm, particularly preferably 5 Nm, whereby an oscillating load assumption is preferably used for the design. The service life (or number of cycles) is designed, for example, according to the desired (maintenance-free) service life of the respective transmission. The maximum torque that can be transmitted (as designed) via the stop device or with the components involved in the second torque stiffness is, for example, at least 80 Nm [eighty Newton meters], preferably above 100 Nm, particularly preferably above 200 Nm.

[0017] Once the maximum angle is reached, the torque stiffness increases to the second torque stiffness, preferably progressively, and a (second) torque stiffness sufficient for the desired maximum motor torque is achieved. It should be noted that in one embodiment, the second torque stiffness is composed of the torque stiffness of the torsionally flexible connecting device and that of the stop device. Alternatively, with the maximum angle reached, the stop device takes over the torque transmission completely (i.e., exclusively), and thus the second torque stiffness is equal to the torque stiffness of the stop device.It should also be noted that the second torque stiffness is not necessarily constant under a changing applied torque, nor can the maximum angle necessarily be exceeded, for example as a result of a further increasing (elastic) compression, bending or torsion.

[0018] In one embodiment, the first torque stiffness is at least one order of magnitude smaller than the second torque stiffness and is therefore negligible compared to the second torque stiffness. In one embodiment, the two torque stiffnesses are of the same order of magnitude, for example the first torque stiffness is half of the second torque stiffness, wherein the second torque stiffness is, as indicated above, composed of the sum of at least the (first) torque stiffness of the torsionally flexible connecting device and the torque stiffness of the stop device (present when the maximum angle is reached). It should be noted that the stop device is not necessarily limited to one component or structural means, but is, for example, composed of several stop components, such as at least one elastomeric block and at least one flange pair.

[0019] It is further proposed in an advantageous embodiment of the damper shaft that the torsionally soft connecting device is formed by at least one spoke element.

[0020] A spoke element is designed like a spoke in a wheel, with a long radial extension (relative to the rotational axis of the damper shaft) and a short extension in the circumferential direction. In one embodiment, the spoke element, unlike a conventional spoke, has a long extension in the axial direction. For example, such a spoke element is formed from a sheet metal, preferably made of spring steel, wherein the sheet metal is preferably inserted in a longitudinal groove with an axial length in the rotor-side torque connection and / or in the transmission-side torque connection.

[0021] In each embodiment, the spoke element has a significantly lower flexural rigidity along its radial extent than in any other direction. It should be noted that in one embodiment, a respective spoke element is formed from a plurality of individual elements (e.g., tabs). For easier handling, a spoke element is preferably made in one piece, for example, cut or punched from a sheet metal material.

[0022] It is further proposed in an advantageous embodiment of the damper shaft that a stop component of the stop device made of an elastomeric plastic is arranged radially between at least two adjacent spoke elements, wherein preferably at least one of the stop components and one of the adjacent two spoke elements are firmly connected to one another.

[0023] In one embodiment, the two adjacent spoke elements diverge at an angle. In one advantageous embodiment, a stop component is arranged in this section, which is shaped similarly to a piece of cake. This stop component is preferably shaped accordingly, wherein in one embodiment a distance is formed from the spoke elements and / or the torque connections, or in another embodiment the stop component is in permanent contact with the spoke elements and / or the torque connections. In the latter embodiment, a stepped stiffness is preferably achieved, for example as a result of a free space that can be filled or used by the (compressed or deformed) stop component, into which space the stop component can initially deflect and forms or finds a stop after this space has been completely filled or used (depending on its deformability).In one embodiment, the stop component comprises an elastomeric plastic and, under load, adapts to the freely usable space within the clearance angle. However, after reaching its deformation limits (for example, due to its approximate incompressibility), it becomes hard, resulting in a sudden increase in stiffness or, preferably, a progressive increase in stiffness. In an alternative embodiment, the stop component is designed (at least functionally) like a buckling beam, and from a predetermined buckling length, the stop component encounters a counter-stop and is thus stiffened (suddenly or, preferably, progressively). Alternatively or additionally, from the maximum angle, the stop component encounters a counter-stop (spaced within the clearance angle) (of at least one of the torque connections) in the circumferential direction.Alternatively or additionally, the stop component is composed of several zones that have different stiffnesses (due to the material or shape). For example, a stop component is formed in a core made of a solid elastomer material and is porous or more porous in the contact area (at least with the spoke elements), provided with a foam material, and / or provided with recesses.

[0024] A permanent (fixed) connection between the stop component and a respective spoke element is advantageous to avoid any noise development and / or an undefined relative position between the spoke elements and the respective stop component. In one embodiment, the stop component is formed (at least partially) from an elastomeric plastic, and the elastomeric plastic is firmly connected to one of the spoke elements by vulcanization. In one embodiment, the type and / or shape of the connection is also used to adjust a desired (at least initial) torque stiffness of the respective spoke element (preferably all spoke elements) (stiffening effect of the fixed connection). This is preferably combined with one of the above-mentioned embodiments with regard to a stiffness graded according to the deformation state.

[0025] In a preferred embodiment, a corresponding distance is maintained on the respective other spoke element (on this side of the fixedly connected stop component) for the clearance angle, so that the stop component does not come into force-transmitting contact as a result of the deformation of the spoke elements under a corresponding torque load before (i.e. only when) the maximum angle is reached.

[0026] It is further proposed in an advantageous embodiment of the damper shaft that the torsionally soft connecting device is formed by a shaft element which meanders axially in an annular region of the damper shaft.

[0027] A meandering structure is characterized by opposing sections (here with reference to the torque transmission) lying next to one another and by reversing connecting sections. In one embodiment, a zigzag shape is formed in the annular region (in a cross-sectional view). In one embodiment, the annular region can be referred to as a folded wave. Preferably, the entire axial extension is used, in which at least one annular section is located, wherein a connecting section is formed at least at one or at each end of the (space-used) extension. In one embodiment, a connecting section is a torque-resistant, for example, materially bonded, connection. Alternatively or additionally, a torque is formed at the connection point or over at least part of the (parallel) extension of the ring in question, a frictionally engaged connection.In one embodiment, the torque-resistant connection is formed in one piece.

[0028] It should be noted that the ring area does not necessarily have to be formed from a circumferentially closed ring. In one embodiment, individual tabs are formed. In one embodiment, the tabs come into force-transmitting contact with each other upon reaching the maximum angle, either directly or via a separate (e.g., elastomeric) stop component, thus achieving a jump in stiffness or, preferably, a progressive increase in stiffness.

[0029] It is further proposed in an advantageous embodiment of the damper shaft that the stop device is formed from an elastomeric plastic and is arranged between the torque connections, wherein the stop device and the torque connections are preferably in force-transmitting contact with each other in every state.

[0030] As already indicated above, an elastomeric plastic (for example, a conventional elastomer or a thermoplastic elastomer [TPE]) is particularly suitable for the task of being able to provide a stiffness jump, or preferably a progressive stiffness increase, while at the same time providing sufficient damping against noise development. In one embodiment of an elastomeric plastic, thermal dissipation can also be used to dampen noise. Alternatively or additionally, (approximate) incompressibility can be used, whereby (as described above) deformability is used for a lower(er) stiffness. Upon reaching a limit of (slight) deformability (preferably determined by the installation space), stiffness increases with a very steep ramp and then remains almost constant (at least below a design torque limit).

[0031] As already mentioned above, permanent contact is advantageous to avoid any noise generation and / or an undefined relative position of the elastomeric plastic relative to the torque connections or the torsionally flexible connecting device. This is preferably combined with one of the above-mentioned embodiments with a stiffness graded according to the deformation state.

[0032] It is further proposed in an advantageous embodiment of the damper shaft that the elastomeric plastic is arranged radially between the torque connections.

[0033] While in one embodiment, for example, the two torque connections each have the elastomeric plastic arranged between them at their axial ends, and optionally also the torsionally flexible connecting device, it is proposed here that the elastomeric plastic be arranged radially between the torque connections for a very small axial installation space requirement. For example, in the embodiment described above with the spoke elements and stop components between the spoke elements, the entire axial extension or a large part of it can be used for torque transmission, so that a relatively soft material can be used for the torsionally flexible connecting device on the one hand, and also (on the other hand) for the stop device, a torsionally rigid material or torsionally rigid behavior can be achieved.This creates a torque softness in the range of low-load torque fluctuations, where the noise emissions considered here can occur, which reduces or even prevents the teeth of the gears involved from lifting and impacting. On the other hand, it is still possible to transmit the desired (maximum) torque safely and with a familiar response, namely by means of the second torque stiffness, which is present at the maximum angle with the aid of the stop device.

[0034] According to a further aspect, a rotor for an electric drive machine is proposed, wherein a damper shaft according to an embodiment as described above is arranged radially inside the rotor and axially overlapping the rotor.

[0035] Here, an advantageous rotor is proposed in which noise emissions are reduced or suppressed during low-load torque fluctuations. At the same time, a (for example maximum) torque can be transmitted without disruption under load. In the embodiment proposed here, the damper shaft is also integrated into the rotor in a space-neutral manner. Often, especially when torque is required in the motor vehicle sector, a minimum or possible inner diameter of a rotor is very large and allows the storage of functional components with a small outer diameter. This is made possible with the damper shaft as described herein. It should be noted that in an advantageous embodiment, the damper shaft is arranged axially entirely within the rotor in question. Alternatively, at least part of the damper shaft protrudes axially from the rotor in question.Particularly preferably, the rotor in question is supported exclusively by the damper shaft, with the damper shaft preferably having only a plain bearing internally, or particularly preferably no bearing at all. The latter is easily achieved with the aforementioned spoke elements, which, in addition to a low (first) torque stiffness (i.e., forming the torsionally flexible connecting device), also offer (sufficiently) high radial and axial stiffness for most applications.

[0036] A suitable rotor (of a radial flux machine), for example, has a diameter of 180 mm [one hundred and eighty millimeters] to 220 mm, or even up to 350 mm for heavy-duty applications. A suitable damper shaft has a diameter of, for example, 30 mm [thirty millimeters] to 60 mm, or even up to 120 mm for heavy-duty applications. For an axial flux machine, larger diameters are common, although the damper shaft may be the same size or larger than that of a radial flux machine. For example, the rotor of an axial flux machine has a diameter of 200 mm [two hundred millimeters] to 300 mm, or even up to 400 mm for heavy-duty applications. A suitable damper shaft has a diameter of, for example, 50 mm [fifty millimeters] to 75 mm, or even up to 150 mm for heavy-duty applications.

[0037] According to a further aspect, a drive train for a motor vehicle is proposed, comprising at least the following components: - at least one prime mover as a torque source for providing a torque; - at least one consumer for converting at least part of a torque provided by at least one of the torque sources; - a transmission for transmitting at least part of a torque provided by the torque sources to the consumer, wherein at least one damper shaft according to an embodiment as described above is arranged between two torque sources and / or between a

[0038] Torque source and the at least one consumer, wherein preferably at least one of the rotors is designed according to an embodiment according to the above description.

[0039] When multiple drive motors are used, they must be synchronized with each other or decoupled. The latter is largely not implemented in current applications due to the cost of a separating clutch and the rapid controllability of electric drive motors. In a hybrid powertrain with one of the drive motors configured as an internal combustion engine, a gear rattling noise is possible due to the speed fluctuation inherent in an internal combustion engine as a result of the ignition timing if the preload on the meshing teeth of the gears involved is too low. The latter is a desirable operating condition for efficient operation.A second critical condition occurs during purely electric driving or with a (pure) electric axle (driveline with only one or more electric drive motors) during a load change, potentially resulting in a clunk noise (change of engagement to the opposite tooth flank). It should be noted that a low-load operating condition exists not only during idle, but also when an electric drive motor is controlled to the speed of the other drive motor (particularly relevant for an internal combustion engine) in order to free the driveline from drag torque (at least with regard to this electric drive motor).

[0040] The transmission comprises at least one gear pair, preferably exclusively spur gear teeth, the tooth flanks of which are prevented from lifting off from one another by means of the at least one damper shaft in a low-load operating state, or at least from hitting one another again at a reduced speed (namely damped), so that noise emission is prevented or at least significantly reduced.

[0041] An advantageous solution to the problem presented here consists in a torsional vibration damping unit that has one or more of the following properties in combination: - integrated between the rotor of the electric (drive) machine and the rotor shaft. - alternatively integrated in the electrical branch of a purely electric motor or hybrid drive train in a shaft. - only covers torque ranges well below the maximum torque of the electric (drive) machine. - is equipped with low friction and rigidity. - dynamically decouples the mass inertia (especially the impact mass) of the electric (drive) machine. - can be constructed as an elastomer damper, spoke damper, torsion shaft, clearance angle with parallel friction. - has a downstream stop for transmitting the full torque of the electric (drive) machine. - is designed as a bearing unit, especially in the arrangement between the rotor and the rotor shaft. - is intended for use in hybrid transmissions, hybrid modules, electric motors and electric axles.

[0042] According to a further aspect, a motor vehicle is proposed, comprising at least one drive wheel and a drive train according to an embodiment according to the above description, wherein, for propelling the motor vehicle, a torque can be delivered from the at least one drive motor of the drive train to the at least one drive wheel, wherein in a low-load operating state, noise emission in the drive train is reduced or suppressed by means of its at least one damper shaft.

[0043] The motor vehicle is, for example, a passenger car, a truck, or a motorized two-wheeler. The motor vehicle has a drive train according to one embodiment as described above. The torque output by the at least one prime mover is transmitted via the transmission to the at least one drive wheel (consumer). In one embodiment, the transmission referred to here comprises a switchable transmission. In one embodiment, the transmission comprises a differential.

[0044] The motor vehicle proposed here comprises a drivetrain with at least one damper shaft, by means of which noise emissions due to tooth lift-off in low-load operating conditions can be significantly reduced or suppressed effectively and cost-effectively. At the same time, the damper shaft can be used without requiring additional installation space, allowing conventional or conventionally designed components to continue to be used unchanged. Compared to a drivetrain without a damper shaft, the drivetrain proposed here can also be designed for more efficient operation.

[0045] The invention described above is explained in detail below against the relevant technical background with reference to the accompanying drawings, which show preferred embodiments. The invention is in no way limited by the purely schematic drawings, whereby it should be noted that the drawings are not to scale and are not suitable for defining proportions. It is shown in Fig. 1: a gearbox with three connected drive motors for a drive train; Fig. 2: a transmission with a connected electric drive motor for a drive train; Fig. 3: a damper shaft within a rotor in a first embodiment in a schematic half-sectional view; Fig. 4: the damper shaft according to Fig. 3 in a schematic cross-sectional view; Fig. 5: a damper shaft within a rotor in a second embodiment in a schematic half-sectional view; and Fig. 6: a drive train in a motor vehicle.

[0046] In Fig. 1 is a transmission 23 with three connected drive motors 4, 5, 6 for a drive train 19 (for example for a motor vehicle 20, compare Fig. 6) is shown in a schematic circuit diagram, with the first drive motor being designed as an internal combustion engine 4 and the other two as electric drive motors 5, 6. This is therefore a hybrid drive train. The electric drive motors 5, 6 each comprise a rotor 17, 18. At the circles designated as damper shaft 1 in the transmission 23, there are suitable locations for the (alternative or additional) use of a damper shaft 1 in the transmission 23. It should be noted that the location of impact is designated and not necessarily the (primarily axially) definitively limited position 29 in the transmission 23 or in the respective shaft. Preferably, the (optional) damper shaft 1 in the first electric drive motor 5 and / or the (optional) damper shaft 1 in the second electric drive motor 6 are arranged axially within the respective rotor 17, 18 (cf. Fig. 3 to Fig. 5). It should be noted that the schematic diagram does not represent a geometric relative position 29 and / or relative sizes, but should be interpreted purely functionally. Furthermore, the size ratio of the gears shown does not indicate the preferred gear ratio, but merely provides an indication of a gear ratio or reduction.

[0047] Here, each of the drive motors 4, 5, 6 is (purely optionally) configured to provide a torque, i.e., a torque source. It is not excluded that a torque (referred to as thrust torque when used in a drive train 19 of a motor vehicle 20) is input into the respective torque source. Furthermore, it is not excluded that a torque source (for example, the first electric drive motor 5 and / or the internal combustion engine 4) is used solely for internal purposes, for example, to generate electrical current. In the embodiment shown, the (third) torque flow 27 to the consumer-side differential 24 can be interrupted by means of a separating clutch 33 (preferably the only one in the drive train 19).

[0048] The first electric drive machine 5 is configured, for example, for towing the internal combustion engine 4 and / or for a boost operation to assist the internal combustion engine 4, and preferably for generating electrical power in generator operation, especially in a mode for increasing the (battery-electric) range, when the internal combustion engine 4 and the first electric drive machine 5 are decoupled from the differential 24 by means of the separating clutch 33.

[0049] The second electric drive motor 6 is, for some operating points, used as the sole torque source of the drive train 19 for direct torque utilization of a consumer 21, 22 (for example, the propulsion of a motor vehicle 20) and is here (purely optionally) inseparably connected to the differential 24. For example, for city driving, the second electric drive motor 6 is sufficient as a torque source, and operation of the internal combustion engine 4 is not required.

[0050] The (first) torque flow 25 between the internal combustion engine 4 and the first electric drive motor 5 is therefore uninterruptible. Thus, in every operating state in which the internal combustion engine 4 delivers torque, there is a potential for noise emissions due to tooth lift-off in a low-load operating state. This noise emission is caused by the situation explained above, namely that intrinsic to an internal combustion engine 4, a speed fluctuation is caused by the ignition timing; thus, gear chatter can occur if the preload on the meshing teeth of the gears 28 involved is too low for this.However, such a noise emission is often also possible in the (second) torque flow 26 of the second electric drive machine 6, namely when both transmission sub-trains on both sides of the differential 24 are simultaneously connected to the differential 24 (disconnect clutch 33 closed) and at least (or above all alone) the internal combustion engine 4 is operated to deliver torque.

[0051] A second critical condition occurs during a load change, potentially resulting in a clunk noise (change of contact to the opposite tooth flank). This is particularly critical in electric drive motors 5, 6, because they generally do not feature other torsional damping devices, such as those commonly found in internal combustion engines 4 (e.g., dual-mass flywheel, centrifugal pendulum-absorbing damper, multi-flange damper, or rocker damper).

[0052] In Fig. 2 shows a transmission 23 with a (single) connected electric drive motor 6 for a drive train 19. Such a transmission 23 is also generally referred to as an electric axle. For the sake of clarity, this is shown as the (second) electric drive motor 6 and its partial transmission train (in the area of ​​the second torque flow 26 of the second electric drive motor 6) up to a differential 24. A transmission 23 driven by an internal combustion engine 4 (cf. Fig. 1) is not necessarily problematic here. However, the same second critical condition is dampened here as with regard to the Fig. 1, namely the situation during a load change and the possible consequence of a clonk noise. For further details, reference is also made to the previous description with reference to the Fig. 1.

[0053] In Fig. 3 shows a damper shaft 1 within a rotor 17 in a first embodiment in a schematic half-sectional view. For better clarity, identical components (pars-pro-toto) are provided with a reference numeral only above or below the rotational axis 2. The damper shaft 1 is designed for rotation about the rotational axis 2 and is mounted by means of (preferably exclusively two) rolling bearings 34, wherein the rotor 17 is simultaneously mounted by means of these rolling bearings 34 (preferably also axially supported). The damper shaft 1 comprises a rotor-side torque connection 7 (connection to the rotor 17) and a transmission-side torque connection 8 (connection to the transmission 23, here to a gear 28), wherein the transmission-side torque connection 8 is arranged centrally. Between the torque connections 7, 8 are a torsionally flexible connecting device 12, from which here (with the aid of the Fig. 4) a spoke element 13 can be seen above and below the rotation axis 2, and a stop device 9, of which here (with the help of the Fig. 4) a stop component 14 can be seen above and below the rotation axis 2, over which a clearance angle 10 (compare Fig. 4) between the rotor-side torque connection 7 and the transmission-side torque connection 8 is predetermined and limited to a maximum angle 11. The spoke elements 13 are accommodated in a receiving shaft 35, which here (purely optionally) forms the transmission-side torque connection 8. It can be clearly seen here that the torsionally flexible connecting device 12 and the stop device 9 are arranged completely radially and completely axially within the rotor 17.

[0054] Due to their long radial extension and small expansion in the circumferential direction, the spoke elements 13 provide a low (first) torque stiffness between the torque connections 7, 8. Upon reaching a predetermined maximum angle 11, the stop components 14 create an on-block situation, resulting in a (preferably progressive) steep increase in stiffness to the higher (second) torque stiffness. The on-block situation is a (force-transmitting) contact of the spoke elements 13 against the adjacent stop components 14. It should be noted that the presence of an on-block situation only upon reaching the maximum angle 11 does not preclude the spoke elements 13 and the stop components 14 from being in permanent contact with each other (possibly also force-transmitting).In an on-block situation, however, a material-related and shape-related (strongly progressive) increase in stiffness is generated (for example, in the case of a stop component 14 made of an elastomeric plastic due to the incompressibility).

[0055] As soon as the maximum angle 11 is reached, the torque stiffness increases to the second torque stiffness, for example progressively or abruptly, and a (second) torque stiffness sufficient for the desired maximum engine torque and thus a desired response behavior is achieved.

[0056] A first preferred embodiment is designed with torsionally flexible spokes (elements) 13. The rotor 17 is connected in a torsionally flexible (and preferably frictionless) manner in the torsional direction via radial, star-shaped sheet metal segments for small angles of rotation (i.e., the decoupling area). In the radial direction, the rotor 17 is rigidly mounted on the rotor shaft via the sheet metal segments. Larger angles of rotation (e.g., when the electric motor's full torque is applied) are transmitted with damping via an end stop (e.g., an elastomer).

[0057] In Fig. 4, the damper shaft 1 is according to Fig. 3 in a schematic cross-sectional view. Reference is made to the previous description in this regard. It is clearly visible that the torsionally flexible connecting device 12 is here (purely optionally) designed from a plurality of spoke elements 13 arranged circumferentially next to one another, and furthermore (purely optionally) a (pie-shaped) stop component 14 of the stop device 9 is provided between each two spoke elements 13 (only two of these components are provided with reference numerals pars-pro-toto). Furthermore, it is clearly visible that the torsionally flexible connecting device 12 and the stop device 9 are arranged completely radially within the rotor 17.

[0058] In this embodiment, two adjacent spoke elements 13 diverge at an angle. A stop component 14 is arranged in this space (shaped similarly to a slice of cake). In this exemplary embodiment, the stop component 14 comprises an elastomeric plastic and, under load, adapts within the clearance angle 10 around a neutral position 36 (shown here) or neutral angular position into the freely usable space. However, it is then hard at the latest after reaching its deformation limits (for example, due to its approximate incompressibility), thus resulting in a progressive increase in stiffness.

[0059] Only when the maximum angle 11 is reached are the rotor-side torque connection 7 and the gearbox-side torque connection 8 connected to each other in a torque-transmitting manner by means of the stop device 9. If the torque applied around the rotation axis 2 and its resulting vector exceeds the maximum angle 11, torque is transmitted to the rotor-side torque connection 7 or the rotor connection 3. Thus, at low torques (for example, during zero-torque transitions), for example, an electric drive motor 5 connected to an internal combustion engine 4 in a torque-transmitting manner, soft damping is achieved and tooth lift-off is reduced or suppressed, thus preventing unwanted noise generation.

[0060] In Fig. 5 shows a first embodiment of a damper shaft 1 within a rotor 17 in a schematic half-sectional view. Without excluding generality, the embodiment shown here is largely identical to the one shown in Fig. 3 and Fig. 4 described embodiment, and therefore reference is made to the description therein and only the differences are discussed below. Regarding the stepped damping function, reference is made to the description of the Fig. 4.

[0061] The torsionally flexible connecting device 12 here is an axially intermeshing shaft element 16. This creates a long, torsionally flexible connection between the rotor-side torque connection 7 and the gearbox-side torque connection 8 (or the receiving shaft 35). The meandering structure of the shaft element 16 is characterized by opposing sections (with respect to the torque line 37) lying next to one another, as well as reversing connecting sections 38. In this exemplary embodiment, a zigzag shape is formed in the annular region 15, which can be understood from the representation of the torque line 37. The respective axial ends of the meandering shaft element 16 are supported within the annular region 15 by bearings 29 (for example, plain bearings or roller bearings), as shown.The meandering shaft element 16 forms the rotor-side torque connection 7 radially outward, and the gearbox-side torque connection 8 to the receiving shaft 35 is formed centrally. The stop device 9 here also comprises a plurality of stop components 14, which are formed overlapping the meandering shaft element 16 in the circumferential direction between the rotor-side torque connection 7 and the receiving shaft 35.

[0062] Here, the individual elements (in cross-section here purely optionally wedge-shaped) of the meandering shaft element 16 are firmly connected to one another (for example meandering, i.e. alternating left and right in the illustration, connected to one another, for example soldered or welded) and the bearings 29 are provided for sufficient radial and axial rigidity, while the (first) torque rigidity is (primarily) defined by the length of the meandering structure and the previously mentioned end connection points.

[0063] When the maximum angle 11 is reached, torques can be transmitted in a damped manner, either additionally or solely, via the stop device 9, for example, with a plurality of stop components 14 (preferably made of an elastomeric plastic). This achieves a second, higher torque stiffness in this operating state, i.e., a stepped torque stiffness dependent on an applied angle (and thus torque) is provided.

[0064] In Fig. 6 shows a plan view of a drive train 19 in a motor vehicle 20, wherein two drive motors 4, 6 are arranged perpendicular to a longitudinal axis 30, along an engine axis 31. The drive motors 4, 6 are arranged in the direction of travel in front of a driver's cab 32 of the motor vehicle 20. The drive train 19 is designed to propel the motor vehicle 20 by driving a left drive wheel 21 and a right drive wheel 22 (here optionally the front axle of the motor vehicle 20) by means of a (preferably dedicated) torque output from the drive motors 4, 6 via a transmission 23. The transmission 23 is designed, for example, according to Fig. 1, wherein the first electric drive machine 5 shown there is not present or not shown here (purely optional), for example as a (coaxial or axially parallel) hybrid module arranged axially between the internal combustion engine 4 and the transmission 23.

[0065] The drive train 19 is designed, for example, such that the motor vehicle 20 can be driven either purely electrically, i.e., only with the electric drive motor 6, or only with the internal combustion engine 4, or in a combination of both drive motors 4, 6. By means of the damper shafts 1 arranged within the drive train 19, a reduction in noise emissions, for example, during zero crossings at the electric drive motor 6, can be implemented within the drive train 19 in a space-neutral manner.

[0066] With the damper shaft proposed here, noise emissions caused by zero crossings can be reduced in a space-neutral manner. List of reference symbols 1 damper shaft 2 rotation axis 3 Rotor connection 4 Internal combustion engine 5 first electric drive machine 6 (second) electric drive machine 7 rotor-side torque connection 8 gearbox-side torque connection 9 Anchor device 10 clearance angles 11 Maximum angle 12 torsionally soft connecting device 13 spoke element 14 Stop component 15 ring area 16 meandering wave element 17 first rotor 18 (second) rotor 19 Powertrain 20 motor vehicles 21 first drive wheel 22 second drive wheel 23 gearboxes 24 Differential 25 first moment flow 26 (second) moment flow 27 third moment flow 28 gear 29 camps 30 Longitudinal axis 31 Motor axle 32 Driver's cab 33 Separating clutch 34 rolling bearings 35 receiving shaft 36 Neutral position 37 Torque line 38 connecting section

Claims

[1] Damper shaft (1) with a rotation axis (2) for a rotor connection (3) of an electric drive machine (5, 6), comprising at least the following components: - a rotor-side torque connection (7); - a gearbox-side torque connection (8); - a stop device (9), via which a clearance angle (10) between the rotor-side torque connection (7) and the gearbox-side torque connection (8) is predetermined to a maximum angle (11), and only when the maximum angle (11) is reached are the rotor-side torque connection (7) and the gearbox-side torque connection (8) connected to one another in a torque-transmitting manner by means of the stop device (9) with a second torque stiffness; and - a torsionally soft connecting device (12), wherein within the clearance angle (10) the rotor-side torque connection (7) and the gearbox-side torque connection (8) are connected to one another in a torque-transmitting manner by means of the torsionally soft connecting device (12) with a first torque stiffness, wherein the first torque stiffness is lower than the second torque stiffness. [2] Damper shaft (1) according to claim 1, wherein the torsionally soft connecting device (12) is formed by at least one spoke element (13). [3] Damper shaft (1) according to claim 2, wherein a stop component (14) of the stop device (9) made of an elastomeric plastic is arranged radially between at least two adjacent spoke elements (13), wherein preferably at least one of the stop components (14) and one of the adjacent two spoke elements (13) are firmly connected to one another. [4] Damper shaft (1) according to one of the preceding claims, wherein the torsionally soft connecting device (12) is formed by a shaft element (16) which axially meanders in an annular region (15) of the damper shaft (1). [5] Damper shaft (1) according to claim 4, wherein the stop device (9) is made of an elastomeric plastic and is arranged between the torque connections (7, 8), wherein preferably the stop device (9) and the torque connections (7,8) are in force-transmitting contact with each other in every state. [6] Damper shaft (1) according to claim 4 or claim 5, wherein the elastomeric plastic is arranged radially between the torque connections (7,8). [7] Rotor (17,18) for an electric drive machine (5,6), wherein a damper shaft (1) according to one of the preceding claims is arranged radially inside the rotor (17,18) and axially overlapping with the rotor (17,18). [8] Drive train (19) for a motor vehicle (20), comprising at least the following components: - at least one drive machine (4,5,6) as a torque source for providing a torque; - at least one consumer (21, 22) for converting at least part of a torque provided by at least one of the torque sources; - a transmission (23) for transmitting at least part of a torque provided by the torque sources to the consumer (21, 22), wherein at least one damper shaft (1) according to one of Claim 1 to Claim 6 is arranged between two torque sources and / or between a torque source and the at least one consumer (21, 22), wherein preferably at least one of the rotors (17,18) is designed according to claim 7. [9] Motor vehicle (20), comprising at least one drive wheel (21, 22) and a drive train (19) according to claim 8, wherein, for propelling the motor vehicle (20), a torque can be delivered from the at least one drive motor (4, 5, 6) of the drive train (19) to the at least one drive wheel (21, 22), wherein in a low-load operating state, noise emission in the drive train (19) is reduced or suppressed by means of its at least one damper shaft (1).

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