Drive unit for a vehicle

Abstract

The invention relates to a drive unit for a vehicle comprising an electric motor (3, 4) for at least periodically driving the vehicle by supplying electrical power to the electric motor (3, 4), a pedal crankshaft (2) for receiving muscular force to at least periodically drive the vehicle via muscular force, and an output element (14) via which a drive force for driving the vehicle can be output by the drive unit. A transmission with a predetermined transmission ratio is provided, which is coupled to an output element (5) of the electric motor (3, 4) on the input side and which can be coupled to the output element (14) of the drive unit via a transmission output element (9) on the output side. In addition, a pedal crankshaft output element (12) coupled to the pedal crankshaft (2) is provided, which can be coupled to the output element (14) of the drive unit. The drive unit has a torque-limiting assembly (20) which is designed for limiting a torque acting on a rotor (3) of the electric motor.

Description

[0001] ZF Friedrichshafen AG File 213547 Friedrichshafen 2022-08-09 Drive device for a vehicle Technical field The present invention relates to a drive device for a vehicle which is driven at least temporarily by an electric motor and at least temporarily by muscle power. In particular, the invention relates to a drive device for a vehicle in which the drive power of an electric motor and the drive power generated by muscle power can be combined and used to drive the vehicle. The vehicle can be designed as an e-bike or pedelec in which the drive by muscle power can be supported by the drive of the electric motor. State of the art The prior art according to DE 102015100676 B3 describes a drive device for a bicycle or a pedelec. In this drive device, an electric motor is used to generate drive power for the vehicle.The electric motor is coupled to an output element of the drive device via a shaft gear. The prior art according to EP 2976551 B1 describes a pin-ring gear, which represents a design of a shaft gear with which a predetermined gear ratio can be provided for transmitting a drive force. Description of the invention: A drive device for a vehicle comprises the following: an electric motor for at least temporarily driving the vehicle by supplying electrical power to the electric motor, a pedal crankshaft for absorbing muscle power for at least temporarily driving the vehicle by muscle power, and an output element, via which drive force for driving the vehicle can be output from the drive device.The drive device further comprises a transmission with a predetermined gear ratio, which is coupled on the input side to an output element of the electric motor and which, on the output side, can be coupled to the output element of the drive device via a transmission output element. ZF Friedrichshafen AG File 213547 Friedrichshafen 2022-08-09. Furthermore, the drive device comprises a pedal crankshaft output element coupled to the pedal crankshaft, which can be coupled to the output element of the drive device. The drive device comprises a torque limiting assembly configured to limit a torque acting in the power transmission path between the electric motor and the output element. The drive device can be permanently mounted on the vehicle. The drive device can be designed as an assembly and mountable on the vehicle in such a way that a compact design is enabled.The vehicle can be intended for the transport of people. In addition, the vehicle can be intended for the transport of goods. The vehicle can be designed as a single-track vehicle. Alternatively, the vehicle can be designed as a multi-track vehicle. The vehicle can be designed as an e-bike or pedelec, in which both muscle power and the drive power of an electric drive can be used to propel the vehicle. An electrical energy storage device can be provided with which the electric motor of the drive device can be operated. Furthermore, a control device can be provided with which the operation of the electric motor can be controlled. The vehicle can have pedals that are mounted on the pedal crankshaft to enable the introduction of muscle power.According to one embodiment, the transmission can have a support element coupled to a housing of the drive device for supporting a reaction torque, wherein the torque limiting assembly can be provided in the power transmission path between the support element and the housing in order to limit the support torque to a predetermined maximum support torque. According to one embodiment, if the predetermined maximum support torque is exceeded, the torque limiting assembly can permit rotation of the support element of the transmission relative to the housing, so that the torque acting on the rotor of the electric motor due to the reaction torque can be limited to a permissible torque.ZF Friedrichshafen AG File 213547 Friedrichshafen 2022-08-09 According to one embodiment, the torque limiting assembly can be provided in the power transmission path between the output element of the electric motor and an input side of the transmission in order to limit the torque transmitted via the power transmission path between the output element of the electric motor and the input side of the transmission to a predetermined maximum torque. According to one embodiment, if the predetermined maximum torque is exceeded, the torque limiting assembly can permit rotation of the output element of the electric motor relative to the input side of the transmission, so that the torque acting on the rotor of the electric motor can be limited to a permissible torque.According to one embodiment, the torque limiting assembly can be provided in the power transmission path between the transmission output element and the output element of the drive device in order to limit the torque transmitted via the power transmission path between the transmission output element and the output element of the drive device to a predetermined maximum torque. According to one embodiment, if the predetermined maximum torque is exceeded, the torque limiting assembly can permit rotation of the transmission output element relative to the output element, so that the torque acting on the rotor of the electric motor can be limited to a permissible torque. The torque acting on the rotor of the electric motor can result from the drive of the electric motor and the transmission function of the transmission.In this case, the torque acting on the rotor of the electric motor corresponds to the existing drive torque of the electric motor. The torque acting on the rotor of the electric motor can additionally or alternatively result from an effect on the transmission. In particular, if an effect is present on the output side of the transmission, this is at least partially transmitted to the rotor of the electric motor via the transmission. Additionally or alternatively, torque surges acting on the output side of the transmission can be transmitted to the rotor of the electric motor via the transmission. ZF Friedrichshafen AG File 213547 Friedrichshafen 2022-08-09. Furthermore, the torque acting on the rotor of the electric motor can result from the dynamic operating mode of the drive device.In particular, the torque acting on the rotor of the electric motor can result from a dynamic mode of operation in conjunction with the inertia of the moving elements involved. Thus, the torque acting on the rotor of the electric motor can be subject to strong fluctuations if there are significant speed changes at the electric motor or if speed fluctuations are induced on the output side of the transmission. According to one embodiment, the torque limiting assembly can have a friction clutch arrangement that is preloaded by a preloading element such that, upon exceeding a predetermined maximum torque applied to the torque limiting assembly, slippage is induced in the friction clutch arrangement, so that the torque limiting assembly permits a relative movement between an input side and an output side of the torque limiting assembly.The friction clutch assembly can be formed from one or more friction clutch discs. Alternatively, the friction clutch assembly can be formed from one or more conical elements. The friction clutch assembly can be arranged axially symmetrically to an axis of symmetry of the drive device. According to one embodiment, the torque limiting assembly can have a positive-locking clutch assembly with a locking body and a locking body receptacle, which are preloaded onto one another by a preloading element to form a positive connection such that when a predetermined maximum torque applied to the torque limiting assembly is exceeded, the locking body releases from the locking body receptacle, so that the torque limiting assembly allows a relative movement between an input side and an output side of the torque limiting assembly. The locking body can be designed as a sphere.ZF Friedrichshafen AG File 213547 Friedrichshafen 2022-08-09 The locking body receptacle can be designed as a body with a recess designed to receive the locking body. If the locking body is designed as a ball, it is particularly advantageous if the locking body receptacle is a circular recess or a spherical recess. The positive-locking coupling assembly can be arranged axially symmetrically to an axis of symmetry of the drive device. The positive-locking coupling assembly can have a plurality of locking elements and, accordingly, a plurality of locking body receptacles assigned to the locking elements. According to one embodiment, the transmission can be designed as a shaft transmission.If the transmission is designed as a shaft transmission, it can have an inner bushing provided with external teeth and coupled to a transmission output element, an outer ring provided with internal teeth, which is a support element of the transmission, and a bushing bearing driven by the electric motor via an input side of the transmission for circumferentially deforming the inner bushing. The external teeth of the inner bushing can have a smaller number of teeth than the internal teeth of the outer ring, and the circumferential deformation of the inner bushing can cause the inner bushing to rotate relative to the outer ring. According to one embodiment, the transmission can be designed as a planetary gear set. If the transmission is designed as a planetary gear set, it can have a sun gear, a ring gear, and a planet carrier that carries at least one planetary gear that meshes with the sun gear and the ring gear.The sun gear, the ring gear, and the planet carrier can form a support element coupled to a housing of the drive device for supporting a reaction torque, an input side of the transmission, and a transmission output element, respectively. In one embodiment, the planetary gear set can be designed such that the sun gear forms an input side of the transmission, the planet carrier forms the transmission output element, while the ring gear forms the support element coupled to the housing of the drive device for supporting the reaction torque. The support element can alternatively be formed by the sun gear or by the planet carrier. The transmission can be designed with more than one planetary gear set ZF Friedrichshafen AG File 213547 Friedrichshafen 2022-08-09, which are coupled to one another. Furthermore, the transmission can be designed as a stepped planetary gear set. According to one embodiment, the transmission can be designed as a spur gear stage.If the transmission is designed as a spur gear stage, it has at least two meshing spur gears supported by a support arrangement. One of the spur gears forms an input side of the transmission, the other of the spur gears forms a transmission output element, and the support arrangement forms a support element of the transmission. The transmission can have more than one spur gear stage. If more than two spur gears are provided, one of the spur gears forms the input side of the transmission and another of the spur gears, via which the drive power of the transmission is output, forms the transmission output element. In this case, too, the support arrangement of the spur gears forms the support element of the transmission. According to one embodiment, the output element can be coupled to an output gear that drives at least one driven wheel of the vehicle via a traction mechanism.In this case, a gear change mechanism can be provided between the output gear and the at least one driven wheel of the vehicle, which gear change mechanism is designed for the stepped change of the gear ratio between the output gear and the at least one driven wheel. The traction means can be a chain that is guided over an arrangement of pinions or chainrings. If the traction means is designed as a chain, the gear change mechanism can be formed by a derailleur. The gear change mechanism designed as a derailleur can be provided with adjusting devices that guide the traction means designed as a chain onto gearwheels with different numbers of teeth. In particular, the derailleur on the driven wheel can have a plurality of pinions with different numbers of teeth. Additionally or alternatively, the derailleur on the pedal crank area can have a plurality of chainrings with different numbers of teeth.By guiding the chain onto a predetermined combination of pinions or chainrings, the gear ratio between the output gear of the drive device and the driven gear of the vehicle can be discretely adjusted. ZF Friedrichshafen AG File 213547 Friedrichshafen 2022-08-09 The gear change mechanism can alternatively be designed as a hub gear on the driven gear of the vehicle. In this case, a gear transmission arrangement can be provided in the region of a hub of the driven gear of the vehicle, with which gear transmission arrangement the gear ratio between the driven gear and a drive element connected to the hub gear can be discretely variable. In this case, the traction means can be a chain. Alternatively, the traction means can be a belt, including a toothed belt. According to one embodiment, a freewheel can be provided in the power transmission path between the transmission output element and the output element.The freewheel between the transmission output element and the output element can be designed such that power can be transmitted from the transmission output element to the output element for driving the vehicle in the forward direction. According to a further embodiment, a freewheel can be provided in the power transmission path between the pedal crankshaft output element and the output element. The freewheel between the pedal crankshaft output element and the output element can be designed such that power can be transmitted from the pedal crankshaft output element to the output element for driving the vehicle in the forward direction. The vehicle of the aforementioned embodiments can be designed as an e-bike or pedelec. In particular, the vehicle can be designed as a single-track vehicle with a front wheel and a rear wheel. The driven wheel of the vehicle can be the rear wheel.The drive device can be mounted on a frame of the vehicle. The vehicle can further comprise an electrical energy storage device which can be provided for supplying electrical energy to the drive device. The vehicle can further comprise an operating element with which the driver can actuate the gear change mechanism. ZF Friedrichshafen AG File 213547 Friedrichshafen 2022-08-09 Brief description of the figures Figure 1 shows a schematic representation of an embodiment of the drive device; and Figure 2 shows a schematic representation of a modified embodiment of the drive device. Detailed description of embodiments Embodiments are described below with reference to the drawings. Figure 1 shows a schematic representation of an embodiment of the drive device for a vehicle.In the view shown in Figure 1, the drive device is shown in section along an axis of symmetry. The drive device of Figure 1 has a housing 1 that forms an outer circumference of the drive device. Fastening means are provided on the housing 1 and are designed to attach the drive device to a vehicle. Located in the housing 1 is a pedal crankshaft 2 that extends axially through the housing 1 and protrudes from the housing 1 at both axial ends. The pedal crankshaft 2 is rotatably mounted within the housing 1. Pedal cranks (not shown in Figure 1) are mounted on the pedal crankshaft 2 and are designed to introduce muscle power into the pedal crankshaft 2. The pedal crankshaft 2 has a pedal crankshaft output element 12, which in the present embodiment is provided as a radial extension on the pedal crankshaft 2.On the outer circumference of the pedal crankshaft output element 12, a first freewheel 13 is provided, with which the pedal crankshaft output element 12 can be coupled to an output element 14 of the drive device. In the present embodiment, the output element 14 is designed as a sleeve-shaped element, on the inner circumference of which the first freewheel 13 is provided. ZF Friedrichshafen AG File 213547 Friedrichshafen 2022-08-09 The output element 14 is rotatably mounted within the housing 1 and protrudes axially from the housing, as shown in Figure 1. A driven gear 15 designed as a gear is provided on the output element 14. Rotation of the output element 14 thus causes rotation of the driven gear 15, which is fixedly connected to the output element 14.When the pedal crankshaft 2 rotates in a first direction, which is associated with a forward direction of the vehicle, the first freewheel 13 transmits the rotation of the pedal crankshaft output element 12 to the output element 14. Thus, in this case, the output gear 15 rotates due to the rotation of the pedal crankshaft 2 in the direction associated with the forward travel of the vehicle. When the pedal crankshaft 2 rotates in the opposite direction relative to the output element 14, the first freewheel 13 opens and the rotation of the pedal crankshaft 2 is not transmitted to the output gear 15. On the left side in Figure 1, an electric motor is provided in a corresponding cavity of the housing 1. The electric motor has a stator 4 that is stationary relative to the housing. Furthermore, the electric motor has a rotor 3 that is arranged radially outside the stator 4 and that is rotatably supported on the housing 1 via a corresponding bearing.The motor with the internal stator 4 and the external rotor 3 is thus designed as an external rotor. In the area to the left of the electric motor in Figure 1, a control device is provided which serves to supply current to the stator 4 of the electric motor from an external energy source. When current is supplied to the stator 4, the winding of the stator 4 is excited and rotation of the rotor 3 of the electric motor is brought about. This rotation of the rotor 3 of the electric motor is transmitted to an output element 5 of the electric motor. A gear is provided on the right-hand side of the electric motor in Figure 1. In the present embodiment, the gear shown in Figure 1 is designed as a shaft gear. The shaft gear has an inner bushing 7, on the outside of which a toothing is provided. The inner bushing 7 is designed as a sleeve that is flexible in the circumferential direction. An outer ring 8 is arranged outside the inner bushing 7.The outer ring 8 has internal teeth that can selectively engage with the external teeth of the inner bushing 7. In the present embodiment, a bushing bearing 6 is provided within the inner bushing 7. The bushing bearing 6 has an outer ring that deviates from a circular shape. In particular, the outer ring of the bushing bearing 6 is elliptical. The inner ring of the bushing bearing 6 is coupled to the output element 5 of the electric motor. When the rotor 3 of the electric motor rotates, the bushing bearing 6 is set in rotation. Due to the non-circular shape of the outer ring of the bushing bearing 6 and its contact with an inner circumference of the inner bushing 7, the inner bushing 7 is circumferentially deformed. As a design characteristic of a shaft gear, the inner bush 7 has a number of teeth that is less than the number of teeth of the internal toothing of the outer ring 8.Thus, when the outer ring 8 is stationary and the bush bearing 6 rotates, the inner bush 7 is set in rotation. The direction of rotation of the inner bush 7 is opposite to the direction of rotation of the rotor 3 of the electric motor. Due to the special design of the shaft gear, high gear ratios of 1:50 or more can be achieved with compact designs. In the present application, an electric motor can therefore be used which has a compact design due to the relatively high rated speeds. In particular, electric motors with a rated speed of 5,000 rpm or more can be used. The reduced speed due to the gear ratio of the gear is transmitted to a support element 10 of the shaft gear, which is rotatably supported on the housing 1 via bearings. A gear output element 9 is coupled to the support element 10 of the shaft gear.The rotation of the support element 10 is transmitted to the transmission output element 9, which lies radially outside the support element 10 of the shaft gear. A second freewheel 11 is provided on the radially outer circumference of the transmission output element 9. The second freewheel 11 lies between the radial outer circumferential surface of the transmission output element 9 and the radial inner circumferential surface of the output element 14 of the drive device. The second freewheel 11 is configured to transmit a rotation of the transmission output element 9, ZF Friedrichshafen AG File 213547 Friedrichshafen 2022-08-09 associated with forward travel of the vehicle, to the output element 14. A rotation of the transmission output element 9 relative to the output element 14 in a direction of rotation opposite to the direction of rotation associated with forward travel is not transmitted to the output element 14.Thus, the rotations of the pedal crankshaft 2 and the transmission output element 9 are combined at the output element 14. In this way, the drive device is designed with a function for combining the muscle power introduced into the pedal crankshaft 2 and the drive force output by the rotor 3 of the electric motor. In the present embodiment, the output gear 15 is designed as a chainring of a bicycle drive. The output gear 15, designed as a chainring, carries a chain (not shown) as a traction means, which is provided with a sprocket set (likewise not shown) on a hub of a rear wheel of the bicycle. In one embodiment, the vehicle has a derailleur system that can guide the chain to sprockets with different numbers of teeth via a derailleur. In the present embodiment, the derailleur is operated by the rider via a control element.During operation of the vehicle, the rider can apply muscle power to the drive system via the pedal crankshaft 2, which is then transmitted to the output element 14 via the first freewheel 13. Simultaneously, or at least temporarily, the drive power of the electric motor can also be transmitted to the output element 14 via the transmission shown in Figure 1 and the second freewheel 11. If, in such an operating state, the rider operates the control element to change the position of the chain in order to change the gear ratio between the output gear 15, designed as a chainring, and the rear wheel, dynamic speed changes occur, and shocks are regularly caused due to the inertia of the mass-bearing elements. Furthermore, during operation of the vehicle, for example, when braking or driving on very uneven ground, strong vibrations and shocks arise in the drive train between the output gear 15 and the rear wheel of the vehicle.ZF Friedrichshafen AG File 213547 Friedrichshafen 2022-08-09 To take these relationships into account, the drive device has a torque limiting assembly 20 shown in Figure 1. In the embodiment shown in Figure 1, the torque limiting assembly 20 has a locking body 23 in the shape of a ball. As shown in Figure 1, the locking body 23 is preloaded to the left in Figure 1 in the direction of a locking body receptacle 24 by a preloading element 22. The locking body receptacle 24 has a recess designed to partially receive the locking body 23. In the torque limiting assembly 20 shown in Figure 1, the locking body receptacle 24 is concentrically constructed and attached to the shaft gear radially outside the outer ring 8 of the shaft gear. On the other side, the locking body 23 with the preloading element 22 is provided in a holder 25 which is provided concentrically on the inner circumference of the housing 1 and is fastened thereto.In the state shown in Figure 1, the locking body 23, designed as a ball, projects into the recess of the locking body receptacle 24 and is preloaded against the locking body receptacle 24 by the preload element 22, designed as a spring. In this state, a positive connection is formed between the locking body receptacle 24 and the holder 25, so that the outer ring 8 remains stationary with respect to the housing 1. In the event that, during operation of the drive device, a relative torque occurs between the locking body receptacle 24 and the holder 25 that is so great that the locking body 23 moves out of the locking body receptacle 24 against the preload force of the preload element 22, a relative rotation between the locking body receptacle 24 and the holder 25 is enabled. In this situation, the outer ring 8 can rotate relative to the housing 1.Therefore, in the event that the support torque acting on the outer ring 8 exceeds a maximum torque, the torque acting on the rotor 3 of the electric motor can be limited. For this purpose, the torque limiting assembly 20, and in particular the spring force of the preloading element 22, is designed according to the specifications for protecting the electric motor. With the present embodiment, it can thus be ensured that excessive torque fluctuations, shocks, and the transmission of strong torques due to the inertia of the overall system are only transmitted to the rotor of the electric motor up to a maximum design value. This improves the function and durability of the electric motor. A further embodiment of the drive device is described below with reference to Figure 2.The essential elements of the drive device shown in Figure 2 correspond to those of Figure 1, and only the differences are described below. While the drive device of Figure 1 has a torque limiting assembly 20 comprising the locking body 23, the locking body receptacle 24, and the holder 25, in the embodiment of Figure 2, a torque limiting assembly 20a is provided at the equivalent position, which assembly includes a friction clutch arrangement 21, preload element 22a, and a holder 26. In a similar manner to the embodiment of Figure 1, in the embodiment of Figure 2, the outer ring 8 is held stationary on the housing 1 via the torque limiting assembly 20a. The torque limiting assembly 20a of Figure 2 has the spring 22a, which is housed in a holder 26. The holder 26 is attached to the inner circumference of the housing 1.On the other side, on the outer circumference of the outer ring 8, the friction clutch assembly 21 is provided. This assembly consists of a plurality of friction clutch elements arranged concentrically around the outer circumference of the outer ring 8. The friction clutch elements comprise stationary friction clutch elements that are non-rotatably mounted on the housing 1 and movable friction clutch elements that are fastened to the outer circumference of the outer ring 8. The stationary and movable friction clutch elements are alternately stacked on top of one another. Due to the spring force of the preload element 22a, the stationary and movable friction clutch elements of the friction clutch assembly 21 are pressed together, so that the outer ring 8 remains stationary relative to the housing 1 up to a certain torque.If the maximum design torque is exceeded, slippage is generated in the friction clutch arrangement 21, so that the stationary and movable friction clutch elements of the friction clutch arrangement 21 can rotate relative to one another and thus the outer ring 8 can rotate relative to the housing 1. ZF Friedrichshafen AG File 213547 Friedrichshafen 2022-08-09 Thus, in a similar manner to the exemplary embodiment in Figure 1, in the embodiment of Figure 2, if a maximum support torque is exceeded, the outer ring 8 can rotate relative to the housing 1. This function has the effect that the maximum torque acting on the rotor 3 of the electric motor can be limited. In further embodiments, the forms of the torque limiting assemblies 20, 20a described above can be used, but the torque limiting assemblies 20, 20a are provided at other positions in the drive device.In an alternative embodiment not shown in the figures, the torque limiting assembly 20, 20a is integrated into the output element 5 of the electric motor. This causes a relative rotation between the output element 5 of the electric motor and the input side of the transmission when a maximum design torque acting on the torque limiting assembly is exceeded. This design can limit the maximum torque acting on the rotor 3 of the electric motor. In an alternative embodiment not shown in the figures, the torque limiting assembly 20, 20a is integrated into the transmission output element 9.In particular, the provision of the torque limiting assembly 20, 20a on the transmission output element 9 ensures that, when a maximum design torque acting on the torque limiting assembly is exceeded, a relative rotation is caused between the transmission output element 9 and the output element 14 of the drive device. With this design, the maximum torque acting on the rotor 3 of the electric motor can be limited. In an alternative embodiment (not shown), the transmission is designed as a planetary gear set. In a further alternative embodiment (not shown), the transmission is designed as a spur gear stage.Other transmission forms are conceivable, as long as the transmission is supported by a support element on the housing of the drive device and, similar to the shaft transmission explained above (ZF Friedrichshafen AG File 213547 Friedrichshafen 2022-08-09), the transmission has an input side coupled to the rotor of the electric motor and a transmission output element that can be coupled to the output element of the drive device. In the present embodiments, the drive device is applied to a bicycle configured as an e-bike or pedelec. In alternative embodiments, the drive device is applied to a multi-track vehicle, in particular to a vehicle with three or four wheels.

[0002] ZF Friedrichshafen AG File 213547 Friedrichshafen 2022-08-09 Reference numeral 1 Housing 2 Pedal crankshaft 3 Rotor electric motor 4 Stator electric motor 5 Output element electric motor 6 Bushing bearing shaft gear 7 Inner bush shaft gear 8 Outer ring shaft gear 9 Gearbox output element 10 Support element shaft gear 11 Second freewheel 12 Pedal crankshaft output element 13 First freewheel 14 Output element 15 Output gear 20, 20a Torque limiting assembly 21 Friction clutch assembly 22, 22a Preload element 23 Locking body 24 Locking body holder 25 Holder 26 Holder

Claims

ZF Friedrichshafen AG File 213547 Friedrichshafen 2022-08-09 Patent claims 1. Drive device for a vehicle, with an electric motor (3, 4) for at least temporarily driving the vehicle by supplying electrical power to the electric motor (3, 4), a pedal crankshaft (2) for absorbing muscle power for at least temporarily driving the vehicle by muscle power, and an output element (14) via which drive power for driving the vehicle can be output from the drive device; a transmission with a predetermined transmission ratio, which is coupled on the input side to an output element (5) of the electric motor (3, 4) and which can be coupled on the output side via a transmission output element (9) to the output element (14) of the drive device; a pedal crankshaft output element (12) coupled to the pedal crankshaft (2) and coupleable to the output element (14) of the drive device;wherein the drive device has a torque limiting assembly (20; 20a) which is designed to limit a torque acting in the power transmission path between the electric motor (3, 4) and the output element (14).

2. Drive device according to claim 1, characterized in that the transmission (3, 4) has a support element which is coupled to a housing (1) of the drive device for supporting a reaction torque, wherein the torque limiting assembly (20; 20a) is provided in the power transmission path between the support element and the housing (1) in order to limit the support torque to a predetermined maximum support torque.

3. Drive device according to claim 2, characterized in that if the predetermined maximum support torque is exceeded by the torque limiting assembly (20;20a) a rotation of the support element of the gear (3, 4) relative to the housing is permitted, so that the torque acting on the rotor (3) of the electric motor (3, 4) due to the reaction torque is limited to a permissible torque; ZF Friedrichshafen AG File 213547 Friedrichshafen 2022-08-09 4. Drive device according to claim 1, characterized in that the torque limiting assembly (20; 20a) is provided in the power transmission path between the output element (5) of the electric motor (3, 4) and an input side of the transmission in order to limit the torque transmitted via the power transmission path between the output element (5) of the electric motor (3, 4) and the input side of the transmission to a predetermined maximum torque.

5. Drive device according to claim 4, characterized in that, when the predetermined maximum torque is exceeded, the torque limiting assembly (20; 20a) permits rotation of the output element (5) of the electric motor (3, 4) relative to the input side of the transmission, so that the torque acting on the rotor (3) of the electric motor (3, 4) is limited to a permissible torque.Drive device according to claim 1, characterized in that the torque-limiting assembly (20; 20a) is provided in the power transmission path between the transmission output element (9) and the output element (14) of the drive device in order to limit the torque transmitted via the power transmission path between the transmission output element (9) and the output element (14) of the drive device to a predetermined maximum torque.

7. Drive device according to claim 6, characterized in that, when the predetermined maximum torque is exceeded, the torque-limiting assembly (20; 20a) permits rotation of the transmission output element (9) relative to the output element (14), so that the torque acting on the rotor (3) of the electric motor (3, 4) is limited to a permissible torque.Drive device according to one of the preceding claims, characterized in that the torque limiting assembly (20a) has a friction clutch arrangement (21) which is prestressed by a prestressing element (22a) in such a way that when a torque limiting element (22a) is exceeded. ZF Friedrichshafen AG File 213547 Friedrichshafen 2022-08-09, wherein a predetermined maximum torque applied to the torque limiting assembly (20a) causes slippage in the friction clutch arrangement (21), so that the torque limiting assembly (20a) permits relative movement between an input side and an output side of the torque limiting assembly (20a). 9.Drive device according to one of the preceding claims, characterized in that the torque limiting assembly (20) has a locking body (23) and a locking body receptacle (24), which are prestressed against one another by a prestressing element (22) to form a positive connection such that when a predetermined maximum torque applied to the torque limiting assembly (20) is exceeded, the locking body (23) is released from the locking body receptacle (24), so that the torque limiting assembly (20) permits a relative movement between an input side and an output side of the torque limiting assembly (20).Drive device according to one of the preceding claims, characterized in that the transmission is designed as a shaft transmission having an inner bushing (7) provided with external teeth and coupled to a transmission output element (9), an outer ring (8) provided with internal teeth, which is a support element of the transmission, and a bushing bearing (6) drivable by the electric motor (3, 4) via an input side of the transmission for circumferentially deforming the inner bushing (7), wherein the external teeth of the inner bushing (7) have a smaller number of teeth than the internal teeth of the outer ring (8), and the circumferential deformation of the inner bushing (7) causes a rotation of the inner bushing (7) relative to the outer ring (8).Drive device according to one of claims 1-9, characterized in that the transmission is designed as a planetary gear set which has a sun gear, a ring gear and a planet carrier which carries at least one planet gear meshing with the sun gear and the ring gear, wherein the sun gear, the ring gear and the planet carrier form a support element which is connected to a housing (1). ZF Friedrichshafen AG File 213547 Friedrichshafen 2022-08-09 Drive device for supporting a reaction torque, forming an input side of the transmission or a transmission output element.

12. Drive device according to one of claims 1-9, characterized in that the transmission is designed as a spur gear stage having at least two meshing spur gears supported by a support arrangement, wherein one of the spur gears forms an input side of the transmission, the other of the spur gears forms a transmission output element, and the support arrangement forms a support element of the transmission. 13.Drive device according to one of the preceding claims, characterized in that the output element (14) is coupled to an output gear (15) which drives at least one driven wheel of the vehicle via a traction means, wherein a gear change mechanism is provided between the output gear (15) and the at least one driven wheel of the vehicle, which gear change mechanism is designed to change the gear ratio between the output gear (15) and the at least one driven wheel in stages.

14. Drive device according to one of the preceding claims, characterized in that a freewheel (11) is provided in the power transmission path between the transmission output element (9) and the output element (14).

15. Drive device according to one of the preceding claims, characterized in that a freewheel (13) is provided in the power transmission path between the pedal crankshaft output element (12) and the output element (14).

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