Vehicle drive unit

Abstract

The drive device for a vehicle includes electric motors (3, 4) that are supplied with electric power to at least temporarily drive the vehicle, a pedal crankshaft (2) that receives muscle power to at least temporarily drive the vehicle, and a driven element (14) that can output drive power for driving the vehicle from the drive device. A gear train with a predetermined transmission ratio is provided, and the gear train is coupled on its input side to an output element (5) of the electric motors (3, 4) and is connectable on its output side to a driven element (14) of the drive device via a gear train output element (9). Furthermore, a pedal crankshaft output element (12) is provided that is connected to the pedal crankshaft (2). The pedal crankshaft output element (12) is connectable to the driven element (14) of the drive device. The drive device includes a torque limiting assembly (20) designed to limit torque acting on a rotor (3) of the electric motor.

Description

[Technical Field]

[0001] The present invention relates to a drive system for a vehicle that is driven at least partly by an electric motor and at least partly by muscle power. In particular, the present invention relates to a drive system for a vehicle that can use a combination of driving force from an electric motor and driving force generated by muscle power to drive the vehicle. The vehicle can be designed as an e-bike or pedelec, in which driving force from muscle power can be supported by driving force from an electric motor. [Background technology]

[0002] The prior art according to DE 10 2015 100 676 B3 describes a drive for a bicycle or pedelec, in which an electric motor is used to generate the driving force for the vehicle, the electric motor being connected to an output element of the drive via a harmonic gear.

[0003] The prior art according to EP 2 976 551 B1 describes a pin-ring transmission which represents a strain wave gear design that is able to provide a predetermined transmission ratio for the transmission of driving forces. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] DE 10 2015 100 676 B3 [Patent Document 2] EP 2 976 551 B1 Summary of the Invention [Means for solving the problem]

[0005] A drive device for a vehicle includes an electric motor that is supplied with electric power to at least temporarily drive the vehicle, a pedal crankshaft that receives muscle power to at least temporarily drive the vehicle, and a driven element that can output drive power for driving the vehicle from the drive device. The drive device further includes a gear device having a predetermined transmission ratio. The gear device is coupled on an input side to an output element of the electric motor and is connectable on an output side to a driven element of the drive device via a gear device output element. In addition, the drive device includes a pedal crankshaft output element connected to the pedal crankshaft. The pedal crankshaft output element is connectable to the driven element of the drive device. The drive device includes a torque limiting assembly that is designed to limit torque acting on a power transmission path between the electric motor and the driven element.

[0006] The drive unit can be permanently attached to the vehicle. The drive unit can be designed as an assembly and can be attached to the vehicle to allow for a compact design. The vehicle can be intended for the transportation of people. Additionally, the vehicle can be intended for the transportation 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 configured as an e-bike or pedelec, in which both muscular power and the drive power of the electric drive unit can be used to drive the vehicle. An electric energy storage device can be provided that can operate the electric motor of the drive unit. Furthermore, a control device can be provided that can control the operation of the electric motor. The vehicle can be provided with pedals attached to the crankshaft to allow the introduction of muscular power.

[0007] According to one embodiment, the gearing may include a support element coupled to the housing of the drive for supporting the reaction torque, and a torque limiting assembly may be provided in the power transmission path between the support element and the housing for limiting the support torque to a predetermined maximum support torque.

[0008] According to one embodiment, when a predetermined maximum support torque is exceeded, a torque limiting assembly allows rotation of the support element of the gearing relative to the housing, thereby limiting the torque acting on the rotor of the electric motor by a reaction torque to the allowable torque.

[0009] According to one embodiment, a torque limiting assembly may be provided in a power transmission path between an output element of the electric motor and an input side of the gearing to limit the torque transmitted through the power transmission path between the output element of the electric motor and the input side of the gearing to a predetermined maximum torque.

[0010] According to one embodiment, when a predetermined maximum torque is exceeded, a torque limiting assembly allows rotation of the output element of the electric motor relative to the input side of the gearing, thereby limiting the torque acting on the rotor of the electric motor to the allowable torque.

[0011] According to one embodiment, a torque limiting assembly may be provided in a power transmission path between the gearing output element and the driven element of the drive device to limit the torque transmitted through the power transmission path between the gearing output element and the driven element of the drive device to a predetermined maximum torque.

[0012] According to one embodiment, a torque limiting assembly allows rotation of the gearing output element relative to the driven element above a predetermined maximum torque, thereby limiting the torque acting on the rotor of the electric motor to the allowable torque.

[0013] In this case, the torque acting on the rotor of the electric motor may result from the drive of the electric motor and the transmission function of the gearing. In this case, the torque acting on the rotor of the electric motor corresponds to the existing drive torque of the electric motor. Additionally or alternatively, the torque acting on the rotor of the electric motor may result from an influence on the gearing. In particular, if there is an influence on the output side of the gearing, this is at least partially transmitted to the rotor of the electric motor via the gearing. Additionally or alternatively, a torque shock affecting the output side of the gearing may be transmitted to the rotor of the electric motor via the gearing.

[0014] Furthermore, the torque acting on the rotor of the electric motor can result from the dynamic operating modes of the drive, in particular from dynamic operating modes related to the mass inertia of the moving elements involved, and can therefore be subject to strong fluctuations when the rotational speed of the electric motor is strongly changed or when rotational speed fluctuations are induced on the output side of the gearing.

[0015] According to one embodiment, the torque limiting assembly may include a friction clutch device biased by a biasing element such that, when a predetermined maximum torque applied to the torque limiting assembly is exceeded, slippage is induced in the friction clutch device, allowing relative movement between the input and output sides of the torque limiting assembly. The friction clutch device may be comprised of one or more friction clutch discs. Alternatively, the friction clutch device may be comprised of one or more conical elements. The friction clutch device may be arranged axially symmetrically with respect to an axis of symmetry of the drive system.

[0016] According to one embodiment, the torque limiting assembly may include a positively coupled clutch device having a locking body and a locking body receiving portion. The locking body and the locking body receiving portion are biased toward one another by a biasing element to form a positive coupling, so that when a predetermined maximum torque applied to the torque limiting assembly exceeds a predetermined maximum torque, the locking body is released from the locking body receiving portion, and the torque limiting assembly allows relative movement between the input side and the output side of the torque limiting assembly. The locking body may be designed as a ball. The locking body receiving portion may be designed as a body having a recess designed to receive the locking body. If the locking body is designed as a ball, it is particularly advantageous for the locking body receiving portion to be a circular or spherical recess. The positively coupled clutch device may be arranged axially symmetrically with respect to the axis of symmetry of the drive device. The positively coupled clutch device may include a plurality of locking elements and a plurality of locking body receiving portions correspondingly assigned to the locking elements.

[0017] According to one embodiment, the gear train can be designed as a strain wave gear train. When the gear train is designed as a strain wave gear train, it can comprise an inner bush with external teeth and connected to the gear train output element, an outer ring that is a support element of the gear train and has internal teeth, and a bush bearing that can be driven by an electric motor via the input side of the gear train to deform the inner bush in the circumferential direction. In this case, the external teeth of the inner bush can have a smaller number of teeth than the internal teeth of the outer ring. The circumferential deformation of the inner bush can cause the inner bush to rotate relative to the outer ring.

[0018] According to one embodiment, the gear train can be designed as a planetary gear set. When the gear train is designed as a planetary gear set, it can include a sun gear, an internal gear, and a planet carrier carrying at least one planet gear that meshes with the sun gear and the internal gear. In this case, the sun gear, the internal gear, and the planet carrier can constitute a support element, an input side of the gear train, or a gear train output element, connected to the housing of the drive device to support the reaction torque. In one embodiment, the planetary gear set can be designed so that the sun gear constitutes the input side of the gear train and the planet carrier forms the gear train output element, while the internal gear constitutes a support element connected to the housing of the drive device to support the reaction torque. The support element can alternatively be constituted by the sun gear or the planet carrier. The gear train can be designed with one or more planetary gear sets connected to each other. Furthermore, the gear train can be designed as a multi-stage planetary gear set.

[0019] According to one embodiment, the gearing can be designed as a spur gear stage. When the gearing is designed as a spur gear stage, it comprises at least two spur gears that mesh with each other and are supported via a support device. In this case, one of the spur gears constitutes the input side of the gearing, and the other spur gear constitutes the output element of the gearing. The support device constitutes the support element of the gearing. The gearing can comprise multiple spur gear stages. When two or more spur gears are provided, one of the spur gears constitutes the input side of the gearing. Another of the spur gears, from which the driving force of the gearing is output, constitutes the output element of the gearing. In this case, the support device of the spur gear also constitutes the support element of the gearing.

[0020] According to one embodiment, the driven element can be coupled to a driven gear which drives at least one driven wheel of the vehicle via a traction means, in which case a gear change mechanism can be provided between the driven gear and the at least one driven wheel of the vehicle, which gear change mechanism is designed to vary the transmission ratio between the driven gear and the at least one driven wheel in stages.

[0021] The traction device may be a chain guided through an arrangement of sprockets or chainrings. If the traction device is designed as a chain, the gear change mechanism may be designed as a derailleur. A gear change mechanism designed as a derailleur may have an adjustment device for guiding the traction means designed as a chain to gears with different numbers of teeth. In particular, the derailleur of the driven wheel may have several sprockets with different numbers of teeth. Additionally or alternatively, the derailleur in the pedal crank area may have several chainrings with different numbers of teeth. By guiding the chain to a predetermined combination of sprockets or chainrings, the transmission ratio between the driven gear of the drive device and the driven wheel of the vehicle can be discretely adjusted.

[0022] Alternatively, the gear change mechanism can be designed as a hub shifting mechanism for the driven wheels of the vehicle. In this case, a gear transmission can be provided in the area of the hub of the driven wheels of the vehicle. By means of the gear transmission, the transmission ratio between the driven wheels and the drive element connected to the hub shifting mechanism can be varied in a discrete manner. In this case, the traction means can be a chain. Alternatively, the traction means can be a belt, including a toothed belt.

[0023] According to one embodiment, a freewheel can be provided in the power transmission path between the gearing output element and the driven element, which can be designed so that the power transmission from the gearing output element to the driven element can drive the vehicle in the forward direction.

[0024] According to a further embodiment, a freewheel can be provided in the power transmission path between the pedal crankshaft output element and the driven element, which can be designed so that the power transmission from the pedal crankshaft output element to the driven element can drive the vehicle in the forward direction.

[0025] The vehicle of the above-described embodiments may be designed as an e-bike or pedelec. In particular, the vehicle may be designed as a single-track vehicle having one front wheel and one rear wheel. In this case, the driven wheel of the vehicle may be the rear wheel. The drive unit may be attached to the frame of the vehicle. The vehicle may further include an electric energy storage device that may be provided to supply electric energy to the drive unit. The vehicle may further include a control element that allows the driver to operate the gear change mechanism. [Brief explanation of the drawings]

[0026] [Figure 1] 1 shows a schematic diagram of one embodiment of a drive arrangement. [Figure 2] 1 shows a schematic diagram of a modified embodiment of the drive device; DETAILED DESCRIPTION OF THE INVENTION

[0027] Embodiments will now be described with reference to the drawings. Figure 1 shows a schematic diagram of an embodiment of a drive device for a vehicle. In the view shown in Figure 1, the drive device is shown cut along an axis of symmetry. The drive device of Figure 1 comprises a housing 1 which forms the outer periphery of the drive device. The housing 1 is provided with fastening means which are designed to fasten the drive device to the vehicle.

[0028] Within the housing 1 is a pedal crankshaft 2 which extends axially through the housing 1 and protrudes from the housing 1 at both axial ends. The pedal crankshaft 2 is rotatably supported within the housing 1. A pedal crank (not shown in FIG. 1) is attached to the pedal crankshaft 2. The pedal crank is designed to transfer muscle power to the pedal crankshaft 2.

[0029] The pedal crankshaft 2 comprises a pedal crankshaft output element 12, which in the present embodiment is arranged on the pedal crankshaft 2 as a radial extension. A first freewheel 13 is arranged on the outer periphery of the pedal crankshaft output element 12. The pedal crankshaft output element 12 can be connected to a driven element 14 of the drive device by means of the first freewheel element 13. In the present embodiment, the driven element 14 is designed as a sleeve-shaped element. The first freewheel 13 is arranged on the inner periphery of the driven element 14.

[0030] 1, the driven element 14 is rotatably mounted inside the housing 1 and projects axially therefrom. The driven element 14 is provided with a driven gear 15 designed as a toothed wheel. Rotation of the driven element 14 therefore causes rotation of the driven gear 15 which is rigidly connected to the driven element 14.

[0031] When the pedal crankshaft 2 rotates in a first direction assigned to the forward movement of the vehicle, the first freewheel 13 transmits the rotation of the pedal crankshaft output element 12 to the driven element 14. In this case, therefore, the rotation of the pedal crankshaft 2 in the direction assigned to the forward movement of the vehicle causes the rotation of the driven gear 15. When the pedal crankshaft 2 rotates in the opposite direction relative to the driven element 14, the first freewheel 13 opens and the rotation of the pedal crankshaft 2 is not transmitted to the driven gear 15.

[0032] On the left side of FIG. 1, an electric motor is located in the corresponding space of the housing 1. The electric motor has a stator 4 fixed to the housing. The electric motor further comprises a rotor 3 arranged radially outside the stator 4 and rotatably supported in the housing 1 via corresponding bearings. A motor with an internal stator 4 and an external rotor 3 is therefore configured as an external rotor. The area located to the left of the electric motor in FIG. 1 is provided with a control device that functions to supply current from an external energy source to the stator 4 of the electric motor. When current is supplied to the stator 4, the windings of the stator 4 are excited, causing the rotor 3 of the electric motor to rotate. This rotation of the rotor 3 of the electric motor is transmitted to the output element 5 of the electric motor.

[0033] A gearing is provided on the right side of the electric motor in FIG. 1. The gearing shown in FIG. 1 is designed as a strain wave gearing in this embodiment. The strain wave gearing comprises an inner bush 7. The inner bush 7 is provided with teeth on its outer side. The inner bush 7 is designed as a circumferentially elastic sleeve. An outer ring 8 is arranged on the outside of the inner bush 7. The outer ring 8 has internal teeth that can selectively engage with the external teeth of the inner bush 7. In this embodiment, a bush bearing 6 is provided inside the inner bush 7. The bush bearing 6 has a non-circular outer ring. In particular, the outer ring of the bush bearing 6 is elliptical. The inner ring of the bush bearing 6 is connected to the output element 5 of the electric motor.

[0034] When the rotor 3 of the electric motor rotates, the bush bearing 6 rotates. The non-circular shape of the outer ring of the bush bearing 6 comes into contact with the inner circumference of the inner bush 7, causing the inner bush 7 to deform over its entire circumference. A characteristic design of strain wave gearing is that the inner bush 7 has fewer teeth than the number of internal teeth on the outer ring 8. Therefore, when the outer ring 8 is stationary and the bush bearing 6 rotates, the inner bush 7 rotates. In this case, the rotation direction of the inner bush 7 is opposite to that of the rotor 3 of the electric motor.

[0035] Due to the special design of the wave gearing, a high transmission ratio of 1:50 or more can be achieved in a compact design. Therefore, in this application, electric motors with compact designs can be used due to their relatively high rated speeds. In particular, electric motors with rated speeds of 5000 rpm or more can be used. The reduced speed resulting from the transmission ratio of the gearing is transmitted to the rotatably supported support element 10 of the wave gearing via a bearing in the housing 1.

[0036] The gear output element 9 is connected to a support element 10 of the wave gearing. The rotation of the support element 10 is transmitted to the gear output element 9, which is located radially outside the support element 10 of the wave gearing. A second freewheel 11 is provided on the radial outer periphery of the gear output element 9. The second freewheel 11 is located between the radial outer periphery of the gear output element 9 and the radial inner periphery of the driven element 14 of the drive device. The second freewheel 11 is therefore designed to transmit the rotation of the gear output element 9, which is assigned to the forward movement of the vehicle, to the driven element 14. The rotation of the gear output element 9 relative to the driven element 14 in a direction of rotation opposite to the direction of rotation assigned to the forward movement is not transmitted to the driven element 14.

[0037] Thus, the rotation of the pedal crankshaft 2 and the rotation of the gearing output element 9 are combined in the driven element 14. In this way, the drive is designed with the function of combining the muscular force introduced into the pedal crankshaft 2 with the drive force output from the rotor 3 of the electric motor.

[0038] In this embodiment, the driven gear 15 is designed as a chain ring of a bicycle drive. The driven gear 15, designed as a chain ring, carries a chain (not shown) as a traction means. The chain is attached to the hub of the rear wheel of the bicycle by a sprocket set (also not shown). In one embodiment, the vehicle is equipped with a derailleur. The derailleur can guide the chain via a rear derailleur to sprockets with a different number of teeth. In this embodiment, the rear derailleur is operated by the rider via a control element.

[0039] When the vehicle is in operation, the driver can apply muscular force to the drive system via the pedal crankshaft 2. This force is transmitted to the driven element 14 via the first freewheel 13. Simultaneously, or at least temporarily, the drive force of the electric motor can be transmitted to the driven element 14 via the gearing shown in FIG. 1 as well as via the second freewheel 11. When the driver operates the operating element to change the chain position in order to change the transmission ratio between the driven gear 15, which is designed as a chain ring, and the rear wheel in this operating state, dynamic speed changes occur, resulting in periodic shocks due to the inertia of the mass-bearing elements. Furthermore, when the vehicle is in operation, for example, during braking or when driving on very uneven road surfaces, strong vibrations and shocks occur in the drivetrain between the driven gear 15 and the rear wheel of the vehicle.

[0040] To take these relationships into account, the drive device includes a torque limiting assembly 20 shown in Figure 1. In the embodiment shown in Figure 1, the torque limiting assembly 20 has a ball-shaped locking body 23. As shown in Figure 1, the locking body 23 is biased to the left by the biasing element 22 of Figure 1, toward the locking body receiving portion 24. The locking body receiving portion 24 has a recess designed to partially receive the locking body 23.

[0041] In the torque limiting assembly 20 shown in FIG. 1 , the locking body receptacle 24 is configured concentrically and attached to the outer ring 8 of the strain wave gearing, radially outside the outer ring 8. On the other hand, the locking body 23 with the biasing element 22 is arranged concentrically on the inner circumference of the housing 1 and is mounted on a holder 25 fixed to the housing 1. In the state shown in FIG. 1 , the locking body 23, designed as a ball, protrudes into a recess in the locking body receptacle 24 and is biased against the locking body receptacle 24 by the biasing 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 relative to the housing 1.

[0042] If, during operation of the drive device, a relative torque is generated between the locking body receiver 24 and the holder 25 that is large enough to move the locking body 23 out of the locking body receiver 24 against the biasing force of the biasing element 22, relative rotation between the locking body receiver 24 and the holder 25 becomes possible. In this situation, the outer ring 8 can rotate relative to the housing 1. Therefore, if the support torque acting on the outer ring 8 exceeds the 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 biasing element 22, are designed according to specifications for protecting the electric motor.

[0043] Therefore, by using this embodiment, excessive torque fluctuations, shocks, and strong torque transmission caused by the inertia of the entire system are transmitted to the rotor of the electric motor only up to the maximum design value, thereby improving the functionality and durability of the electric motor.

[0044] A further embodiment of the drive device will be described below with reference to FIG. 2. Essential elements of the drive device shown in FIG. 2 correspond to those of FIG. 1. Below, only the differences will be described. The drive device of FIG. 1 includes a torque limiting assembly 20 having a stop 23, a stop receiving portion 24, and a holder 25. Meanwhile, in the embodiment of FIG. 2, a torque limiting assembly 20a having a friction clutch device 21, a biasing element 22a, and a holder 26 is provided in a similar position. Similar to the embodiment of FIG. 1, in the embodiment of FIG. 2, the outer ring 8 is held stationary on the housing 1 via the torque limiting assembly 20a. The torque limiting assembly 20a of FIG. 2 includes a spring 22a housed in a holder 26. The holder 26 is attached to the inner periphery of the housing 1. Meanwhile, the outer periphery of the outer ring 8 is provided with a friction clutch device 21 consisting of a plurality of friction clutch elements arranged concentrically around the outer periphery of the outer ring 8.

[0045] The friction clutch elements include a fixed friction clutch element non-rotatably attached to the housing 1 and a movable friction clutch element attached to the outer periphery of the outer ring 8. The fixed friction clutch element and the movable friction clutch element are alternately stacked on top of each other. Due to the spring force of the biasing element 22a, the fixed friction clutch element and the movable friction clutch element of the friction clutch device 21 are pressed together. As a result, the outer ring 8 remains stationary relative to the housing 1 up to a certain torque. When the maximum design torque is exceeded, slippage occurs in the friction clutch device 21. As a result, the fixed friction clutch element and the movable friction clutch element of the friction clutch device 21 can rotate relative to each other. Therefore, the outer ring 8 can rotate relative to the housing 1.

[0046] Thus, similar to the embodiment of Figure 1, in the embodiment of Figure 2, if the maximum support torque is exceeded, the outer ring 8 can rotate relative to the housing 1. This feature makes it possible to limit the maximum torque acting on the rotor 3 of the electric motor.

[0047] In further embodiments, the above-described configuration of the torque limiting assembly 20, 20a can be used, however, the torque limiting assembly 20, 20a is provided at another location in the drive.

[0048] In an alternative embodiment not shown, the torque limiting assembly 20, 20a is integrated into the electric motor output element 5. In this case, exceeding the maximum design torque acting on the torque limiting assembly causes relative rotation between the electric motor output element 5 and the input side of the gearing. This design makes it possible to limit the maximum torque acting on the electric motor rotor 3.

[0049] In an alternative embodiment not shown, the torque limiting assembly 20, 20a is integrated into the gearing output element 9. In particular, by providing the torque limiting assembly 20, 20a on the gearing output element 9, relative rotation is induced between the gearing output element 9 and the driven element 14 of the driver when a maximum design torque acting on the torque limiting assembly is exceeded. This design makes it possible to limit the maximum torque acting on the rotor 3 of the electric motor.

[0050] In an alternative embodiment not shown, the gearing is designed as a planetary gear set. In a further alternative embodiment not shown, the gearing is designed as a spur gear stage. Other gearing configurations are also conceivable, as long as the gearing is supported on the housing of the drive device by means of a support element and has, like the above-mentioned strain wave gearing, an input side that is connected to the rotor of the electric motor and a gearing output element that can be connected to the driven element of the drive device.

[0051] In this embodiment, the drive unit is applied to a bicycle designed as an e-bike or pedelec. In an alternative embodiment, the drive unit is applied to a multi-track vehicle, in particular a vehicle with three or four wheels. [Explanation of symbols]

[0052] 1. Housing 2 pedal crankshaft 3. Electric motor rotor 4 Electric motor stator 5. Electric motor output element 6. Bush bearings for strain wave gearing 7. Inner bush of strain wave gear 8 Outer ring of strain wave gear 9 Gearing Output Elements 10 Strain wave gear device support element 11 Second freewheel 12 pedal crankshaft output element 13 First freewheel 14 Driven element 15 Driven gear 20, 20a Torque limiting assembly 21 Friction clutch device 22, 22a biasing element 23 Locking body 24 Locking body receiving portion 25 Holder 26 Holder

Claims

1. A drive system for a vehicle, An electric motor (3, 4) that drives the vehicle at least temporarily by being supplied with power; a pedal crankshaft (2) that receives muscle force to drive the vehicle at least temporarily by muscle force; and a driven element (14) that can output driving force for driving the vehicle from the drive device, A gear device having a predetermined gear ratio, wherein the gear device is connected to the output element (5) of the electric motor (3, 4) on the input side and is connectable to the driven element (14) of the drive device via the gear device output element (9) on the output side, A pedal crankshaft output element (12) connected to the pedal crankshaft (2), wherein the pedal crankshaft output element (12) comprises a pedal crankshaft output element (12) that can be connected to the driven element (14) of the drive device, A drive system for a vehicle, comprising a torque limiting assembly (20; 20a) designed to limit the torque acting on the power transmission path between the electric motors (3, 4) and the driven element (14).

2. A drive device according to claim 1, wherein the gear devices (3, 4) include support elements connected to the housing (1) of the drive device to support reaction torque, and the torque limiting assembly (20; 20a) is provided in the power transmission path between the support elements and the housing (1) to limit the support torque to a predetermined maximum support torque.

3. The drive device according to claim 2, characterized in that when the predetermined maximum support torque is exceeded, the torque limiting assembly (20; 20a) allows the support element of the gear device (3, 4) to rotate relative to the housing, and as a result, the torque acting on the rotor (3) of the electric motor (3, 4) is limited to an allowable torque by the reaction torque.

4. A drive device according to claim 1, wherein 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 the input side of the gear device in order to limit the torque transmitted through the power transmission path between the output element (5) of the electric motor (3, 4) and the input side of the gear device to a predetermined maximum torque.

5. The drive device according to claim 4, characterized in that when the predetermined maximum torque is exceeded, the torque limiting assembly (20; 20a) allows the output element (5) of the electric motor (3, 4) to rotate relative to the input side of the gear device, and as a result, the torque acting on the rotor (3) of the electric motor (3, 4) is limited to an allowable torque.

6. A drive device according to claim 1, wherein the torque limiting assembly (20; 20a) is provided in the power transmission path between the gear output element (9) and the driven element (14) of the drive device in order to limit the torque transmitted through the power transmission path between the gear output element (9) and the driven element (14) of the drive device to a predetermined maximum torque.

7. The drive device according to claim 6, characterized in that when the predetermined maximum torque is exceeded, the torque limiting assembly (20; 20a) allows the gear device output element (9) to rotate relative to the driven element (14), and as a result, the torque acting on the rotor (3) of the electric motor (3, 4) is limited to an allowable torque.

8. A drive device according to claim 1 or 2, wherein the torque limiting assembly (20a) comprises a friction clutch device (21), and the friction clutch device (21) is biased by a biasing element (22a) such that when a predetermined maximum torque applied to the torque limiting assembly (20a) is exceeded, slippage is induced in the friction clutch device (21), allowing the torque limiting assembly (20a) to move relative to the input side and output side of the torque limiting assembly (20a).

9. A drive device according to claim 1 or 2, wherein the torque limiting assembly (20) comprises a locking body (23) and a locking body receiving portion (24), the locking body (23) and the locking body receiving portion (24) are biased by a biasing element (22) to form a shape coupling, and as a result when a predetermined maximum torque applied to the torque limiting assembly (20) is exceeded, the locking body (23) is released from the locking body receiving portion (24), and the torque limiting assembly (20) is able to move relative to the input side and output side of the torque limiting assembly (20).

10. A drive device according to claim 1 or 2, wherein the gear device is designed as a harmonic drive gear device, and the gear device comprises an inner bush (7) having external teeth and connected to a gear device output element (9), an outer ring (8) which is a support element of the gear device and has internal teeth, and a bush bearing (6) which can be driven by the electric motor (3, 4) via the input side of the gear device to deform the inner bush (7) in the circumferential direction, wherein the external teeth of the inner bush (7) have fewer teeth than the internal teeth of the outer ring (8), and the circumferential deformation of the inner bush (7) causes the inner bush (7) to rotate relative to the outer ring (8).

11. A drive device according to claim 1 or 2, wherein the gear device is designed as a planetary gear set, and the gear device comprises a sun gear, an internal gear, and a planetary carrier supporting at least one planetary gear that meshes with the sun gear and the internal gear, and the sun gear, the internal gear, and the planetary carrier constitute a support element, an input side of the gear device, or an output element of the gear device, which is connected to the housing (1) of the drive device to support a reaction torque.

12. A drive device according to claim 1 or 2, wherein the gear device is designed as a spur gear stage, the gear device comprises at least two spur gears that mesh with each other and are supported via a support device, one of the spur gears constitutes the input side of the gear device, the other of the spur gears constitutes the output element of the gear device, and the support device constitutes the support element of the gear device.

13. A drive device according to claim 1 or 2, wherein the driven element (14) is connected via a traction means to a driven gear (15) that drives at least one driven wheel of the vehicle, and a gear change mechanism is provided between the driven gear (15) and at least one driven wheel of the vehicle, which is designed to change the gear ratio between the driven gear (15) and the at least one driven wheel in steps.

14. A drive device according to claim 1 or 2, characterized in that a free wheel (11) is provided in the power transmission path between the gear device output element (9) and the driven element (14).

15. A drive device according to claim 1 or 2, characterized in that a free wheel (13) is provided in the power transmission path between the pedal crankshaft output element (12) and the driven element (14).

Images