Drive unit for a bicycle with a continuously variable transmission

Abstract

The invention relates to a drive device (2) for a bicycle (1), comprising a pedal crank shaft (19), a first electric machine (18), a first partial transmission (6), a second electric machine (49), and a second partial transmission (7), wherein a first transmission element of the first partial transmission (6) is operatively connected to the first electric machine (18), wherein a second transmission element of the first partial transmission (6) is operatively connected to a second transmission element of the second partial transmission (7), wherein a third transmission element of the first partial transmission (6) is operatively connected to an output gear (8), wherein a first transmission element of the second partial transmission (7) is operatively connected to the second electric machine (49), and wherein a third transmission element of the second partial transmission (7) is fixed to a housing (3), and wherein a freewheel (14) is arranged between the pedal crank shaft (19) and the second transmission element of the first partial transmission (6).Furthermore, the invention relates to a bicycle (1) with such a drive device (2).

Description

[0001] The invention relates to a drive device for a bicycle. Furthermore, the invention relates to a bicycle with such a drive device.

[0002] US Patent 2013 / 012350 A1 discloses a wheel hub drive for a motor vehicle, comprising an electric motor effectively connected to an input element of a transmission. The transmission has an output element connected to a shaft section through which a wheel of the motor vehicle can be driven. A sensor is provided for monitoring the rotational speed of the drive, comprising a rotationally fixed sensor element and a rotatable sensor element, the rotatable sensor element being rotationally fixed to the output element.

[0003] DE 10 2022 205 263 B3 describes a drive unit for a muscle-powered vehicle. A housing, mountable to the vehicle, is provided for at least partial accommodation of drive unit components. A superimposed transmission is designed as a stepped planetary gear set with at least one stepped planetary gear, corresponding ring gears, and an input element. A crank mechanism can be coupled to one of the ring gears, and an output element of the electric machine is coupled to the input element. The superimposed transmission is rotatably arranged relative to the housing, so that the rotation of the electric machine and the rotation of the pedal-driven crank mechanism are superimposed and transmitted to the output gear.

[0004] DE 10 2022 212 262 B3 also describes a drive device for a muscle-powered vehicle, in which a driving force for propelling the vehicle is generated at least temporarily by a muscle force of a driver of the vehicle.

[0005] The subsequently published German patent DE 10 2023 201 654 A1 describes a drive train for a bicycle. This drive train is designed for a continuously variable transmission between a crankshaft and an output shaft. The transmission has three planetary gear sets. A first motor shaft is permanently and rotationally fixed to a first sun gear. A first planet carrier is permanently and rotationally fixed to a second ring gear.

[0006] The first planet carrier is rotationally fixed to a third sun gear. A first ring gear is permanently and rotationally fixed to a second sun gear. A third planet carrier is rotationally fixed to the crankshaft. A third ring gear is rotationally fixed to the output shaft. The second planet gear set is radially interlocked with the first planet gear set.

[0007] The object of the present invention is to propose a drive device for a bicycle with a freely or continuously adjustable transmission that enables high gear ratios. This object is achieved by the subject matter of claim 1 and by the subject matter of claim 2. Preferred embodiments are described in the dependent claims.

[0008] According to a first aspect of the invention, a drive device for a bicycle comprises a pedal crank shaft, a first electric machine, a first partial transmission, a second electric machine, and a second partial transmission, wherein a first transmission element of the first partial transmission is operatively connected to the first electric machine, wherein a second transmission element of the first partial transmission is operatively connected to a second transmission element of the second partial transmission, wherein a third transmission element of the first partial transmission is operatively connected to an output gear, wherein a first transmission element of the second partial transmission is operatively connected to the second electric machine, and wherein a third transmission element of the second partial transmission is fixed to a housing, and wherein a freewheel is arranged between the pedal crank shaft and the second transmission element of the first partial transmission.

[0009] The first electric motor and the first partial gearbox form a first motor-gearbox unit. The second electric motor and the second partial gearbox form a second motor-gearbox unit.

[0010] Each sub-gearbox is a high-ratio gear stage capable of achieving gear ratios of preferably at least 1:30. Each sub-gearbox is designed to have three inputs or outputs. Therefore, wave gears, planetary gears, or eccentric gears, for example, are suitable as sub-gearboxes within the meaning of the invention. Other gear types with three inputs or outputs are also suitable for use in the proposed drive device. "Three inputs or outputs" means that each sub-gearbox comprises one input and two outputs or one output and two inputs. Drive power is introduced into the sub-gearbox via the input. The drive power is either routed out of the sub-gearbox, forwarded, or supported via the respective output.

[0011] The output gear is designed to drive at least an indirect wheel of the bicycle and can be operatively connected to a traction drive or similar mechanism. The output gear transmits the converted drive power, in particular drive torque, for example via the aforementioned traction drive to the driven wheel of the bicycle, especially the rear wheel. The design of the output gear depends on the specific configuration of the power transmission to the driven wheel. For example, the output gear is a sprocket if the traction drive is a chain drive.

[0012] In this context, "at least indirectly" means that two elements or components are effectively connected to each other via at least one further component located between them, or are directly and thus immediately connected to each other. Accordingly, for example, further components or parts, in particular shafts, can be arranged between the respective gear element and the output gear.

[0013] “Fixed to a housing” in the context of this invention means that a torque of the drive device is supported, in particular on the housing or a housing part of the drive device and thus on the frame of the bicycle.

[0014] Muscle power is introduced into the system via the crank axle and transmitted to the first gearbox via the freewheel. The freewheel ensures that the crank axle, when the fixed cranks are at a standstill, is not driven by the inertia of the first motor-gearbox unit. Furthermore, the freewheel allows the rider to pedal backwards with minimal torque and resistance, mimicking the behavior of a conventional bicycle and thus perceived by the rider as familiar and therefore unobtrusive. The crank axle can be hollow or solid. It is preferably arranged concentrically to the first motor-gearbox unit. The freewheel can be either a friction-lock or positive-locking mechanism and may include one or more clamping elements.

[0015] According to the invention, each sub-gearbox of the drive device is either a wave gear or an eccentric gear. The latter is designed as a planetary gear, each comprising a first eccentric gear and a second eccentric gear, which are arranged on the second gear element of the respective sub-gearbox via an eccentric rotatably mounted on the second gear element of the respective sub-gearbox. Each eccentric gear is designed as a planet gear mounted on an associated eccentric, the respective eccentric being rotatably mounted on a planet carrier. The eccentric gears are preferably arranged in a specific angular relationship and have an eccentric rotation. Each eccentric orThe planet gear is configured to mesh with a sun gear or a ring gear, wherein, when one eccentric gear is meshed with its corresponding sun gear, the other eccentric gear is meshed with its corresponding ring gear, and vice versa. The sun gears and / or the ring gears are preferably integrally connected to one another, in any case in a rotationally fixed manner.

[0016] Preferably, the first gear element of the respective sub-gearbox comprises a sun gear or several sun gears connected to each other in a rotationally fixed manner, wherein the second gear element is designed as a planet carrier on which the two eccentric gears are rotatably mounted, and wherein the third gear element comprises a ring gear or several ring gears connected to each other in a rotationally fixed manner. The assignment of the gear elements to the components of the respective sub-gearbox or planetary gearset of the drive device can be adapted as required.

[0017] The two sub-gearboxes are therefore operatively connected to each other via their planet carriers, for example via a coupling drive, which can be designed as a gear stage, in particular as a spur gear set or as a traction drive.

[0018] The ring gear of the first sub-transmission represents the transmission output and is at least indirectly operatively connected to the output gear. In one embodiment, the ring gear of the first sub-transmission is rotationally fixed to the output gear. A first eccentric shaft of the first sub-transmission preferably forms the input of the first sub-transmission and is rotationally fixed to the two sun gears of the first sub-transmission. The first eccentric shaft is to be understood as the first input shaft of the first sub-transmission. The first eccentric shaft is preferably rotationally fixed to a first rotor of the first electric machine. The first stator of the first electric machine is arranged fixed to the frame or indirectly fixed to the frame.

[0019] According to the first aspect of the invention, the first motor-gearbox unit forms a continuously variable transmission (CVT) of the drive device. "CVT" stands for "Electronically Continuously Variable Transmission." With the motor-gearbox unit that implements the CVT function, a transmission ratio can be continuously adjusted between a minimum and a maximum as desired and according to application-specific requirements. Thus, the transmission ratio between input and output speed or input and output torque is continuously varied.

[0020] If the first electric motor, rotor, or input shaft is driven at the same speed as the pedal crankshaft, the first sub-gearbox, especially if it is an eccentric gear, operates in a continuous, uninterrupted loop between the second gear element of the first sub-gearbox (the first planet carrier, which also acts as an input and is operatively connected to the pedal crankshaft via the freewheel) and the third gear element (the first ring gear), which acts as the output. This ensures that the output gear is driven at the same speed as the pedal crankshaft rotates.

[0021] If the first electric machine, or the first rotor, or the first input shaft is driven more slowly than the pedal crankshaft, then the first ring gear and thus the output gear will also be driven more slowly than the pedal crankshaft.

[0022] If the first electric motor, rotor, or input shaft is driven faster than the crankshaft, then the first ring gear, and thus the output gear, is also driven faster than the crankshaft. Due to the gear ratio of the first sub-gearbox, the first electric motor only needs to provide a lower torque than the crankshaft by the gear ratio factor, but at a correspondingly higher speed.

[0023] The freewheel at the gearbox input or on the pedal crankshaft prevents torque transmission from the pedal crankshaft to the gearbox input in the reverse direction of rotation. This occurs when pedaling backwards relative to the vehicle's forward movement, or when the pedal crankshaft rotates more slowly than the gearbox element connected to it via the freewheel. Therefore, reverse movement cannot be initiated by turning the pedal crankshaft backwards. However, reverse movement can be achieved if the first electric motor is driven backwards at a faster speed than the output shaft can stand still. In this case, when the pedal crankshaft is driven, the output shaft will rotate backwards in a direction corresponding to the forward direction. A speed limit can be set for the first electric motor in the reverse direction.be predetermined, so that the same high speed cannot be achieved as with a drive corresponding to forward travel.

[0024] The second motor-gearbox unit takes over the task of providing electric motor assistance to the bicycle. An additional torque is generated by the second electric motor in a known manner, then converted via the second sub-gearbox and transmitted, at least indirectly, to the output wheel. The second motor-gearbox unit can be fundamentally different in design from the first. Alternatively, the first and second motor-gearbox units can be identical, which simplifies the design of the drive system and reduces costs.

[0025] Preferably, the partial transmissions are operatively interconnected via at least one first coupling drive. The coupling drive between the partial transmissions can have a gear ratio other than 1:1 in order to better adapt the second motor-gearbox unit to the specific requirements of the bicycle, for example.

[0026] According to a second aspect of the invention, a drive device for a bicycle comprises a pedal crank shaft, a first electric machine, a first partial transmission, a second electric machine, a second partial transmission, wherein a first transmission element of the first partial transmission is operatively connected to the first electric machine, wherein a second transmission element of the first partial transmission is operatively connected to a third transmission element of the second partial transmission, wherein a third transmission element of the first partial transmission is fixed to a housing, wherein a first transmission element of the second partial transmission is operatively connected to the second electric machine, and wherein a second transmission element of the second partial transmission is operatively connected to an output gear, and wherein a freewheel is arranged between the pedal crank shaft and the second transmission element of the first partial transmission.

[0027] In contrast to the first aspect of the invention, in the second aspect, the second electric machine or the second motor-gearbox unit fulfills the E-CVT function. Thus, the second motor-gearbox unit forms a continuously variable transmission or an E-CVT transmission of the drive device. By varying the speed of the second electric machine, the gear ratio between the pedal crank shaft and the output wheel can be continuously varied. By controlling the second electric machine so that the rotor is driven in reverse, i.e., in a direction of rotation opposite to normal operation, reverse travel can be achieved, during which different gear ratios can also be continuously varied by varying the speed. Accordingly, the first electric machine or the first motor-gearbox unit serves to assist the drive.Everything said regarding the first and second motor-gearbox units according to the first aspect of the invention applies conversely and analogously to the motor-gearbox units according to the second aspect of the invention.

[0028] Regarding the pedal crankshaft, the output gear and the housing, unless otherwise stated, reference is made to the above explanations.

[0029] In one embodiment, each sub-gearbox of the drive device is a wave gear, each comprising a flexible ring element with external teeth, which is actuated by a wave generator and is at least partially deformable in the radial direction, and a rigid ring element with internal teeth. The internal teeth of the rigid ring element mesh with the external teeth of the flexible ring element at at least one tooth engagement area to transmit torque. In contrast to an eccentric gear design, a wave gear can be designed more simply and compactly. Of course, other planetary gears can also be used in the drive device according to the second aspect of the invention.

[0030] The wave generator, also called a "wave generator" in English, is operatively connected to a shaft, which is preferably driven by an associated electric machine to set the wave generator into rotation. Accordingly, the wave generator can form the drive side of the wave gear. For example, the wave generator has an elliptical or oval cross-sectional shape.

[0031] The wave generator preferably has a non-circular bearing element, wherein the bearing element projects at least partially axially into the flexible ring element. The bearing element has an inner ring, an outer ring, and rolling elements arranged spatially between them, wherein the inner ring can be rotationally fixed to the rotor shaft.

[0032] The flexible ring element is a collar sleeve, also known as a "flexspline." It is a high-strength, torsionally rigid sleeve element. Its flexibility allows it to accommodate the shaft generator and bearing element, at least partially axially, while remaining locally deformable depending on the shaft generator's outer shape. Specifically, the shaft generator's outer shape is defined by the bearing element's outer ring. The rolling elements of the bearing element contact the outer circumferential surface of the inner ring, with a first raceway for the rolling elements forming on this outer circumferential surface. Furthermore, the rolling elements also contact the inner circumferential surface of the outer ring, with a second raceway for the rolling elements forming on this inner circumferential surface.The flexible ring element has at least one open axial side for receiving the shaft generator with the bearing element, wherein the inner circumferential surface of the flexible ring element is arranged in the operation of the shaft generator to receive the outer circumferential surface of the outer ring of the bearing element in a rotationally fixed manner.

[0033] During operation, the shaft generator can rotate, causing the inner ring of the bearing element to twist relative to the flexible ring element and the outer ring of the bearing element, which is fixedly mounted within it. During this process, a section of the flexible ring element deforms elastically in accordance with the direction and speed of rotation of the shaft generator. In other words, during operation of the shaft drive, the shaft generator is set into a rotational motion, which causes the flexible ring element to undergo circumferential deformation.

[0034] Preferably, the external teeth of the flexible ring element for transmitting torque engage at least partially with the internal teeth of the rigid ring element in two symmetrically opposed tooth engagement areas relative to the axis of rotation of the wave generator. This allows for uniform force application and transmission, and the respective wave gear can be designed to save space.

[0035] The rigid ring element, also known as a "circular spline," is a torsionally stiff, rigid ring whose internal teeth have more teeth than the external teeth of the flexible ring element. Specifically, the rigid ring element is designed as a ring gear. The rotation of the shaft generator causes a permanent, continuous tooth engagement between the flexible and rigid ring elements. In other words, the opposing tooth engagement areas move continuously around the shaft generator's axis of rotation, i.e., circumferentially, during the shaft generator's rotation. Since the flexible ring element has fewer teeth than the rigid ring element, rotation of the shaft generator causes a relative movement of the flexible ring element to the rigid ring element. This results in the rolling elements of the bearing element rolling between the inner and outer rings.

[0036] The assignment of the gear elements to the components of the respective partial or planetary gear unit of the drive device according to the second aspect of the invention can be adapted as required. According to a first embodiment, the first gear element of the first partial gear unit is a first shaft generator, wherein the second gear element of the first partial gear unit is a first flexible ring element, wherein the third gear element of the first partial gear unit is a first rigid ring element, wherein the first gear element of the second partial gear unit is a second shaft generator, wherein the second gear element of the first partial gear unit is a second flexible ring element, and wherein the third gear element of the first partial gear unit is a second rigid ring element.

[0037] The second gear element of the first sub-gearbox is preferably operatively connected to the third gear element of the second sub-gearbox via a spur gear stage or a traction drive. In the first connection variant described above, the first flexible ring element of the first sub-gearbox is therefore operatively connected to the second rigid ring element of the second sub-gearbox via a coupling drive, in particular via a spur gear stage or a traction drive.

[0038] Alternatively, the assignment of the second and third gear elements to components of the second sub-gearbox can be reversed. According to a second embodiment, the first gear element of the first sub-gearbox is a first wave generator, the second gear element of the first sub-gearbox is the first flexible ring element, the third gear element of the first sub-gearbox is the first rigid ring element, the first gear element of the second sub-gearbox is a second wave generator, the second gear element of the first sub-gearbox is a second rigid ring element, and the third gear element of the first sub-gearbox is a second flexible ring element. In this connection variant, the first flexible ring element of the first sub-gearbox is operatively connected to the second flexible ring element of the second sub-gearbox via a transmission stage, in particular a spur gear stage or a traction drive.

[0039] Preferably, the first electric motor and the first partial gearbox are arranged coaxially with the pedal crank shaft. Alternatively or additionally, the second electric motor and the second partial gearbox are each arranged parallel to the pedal crank shaft. Preferably, the first electric motor and the first partial gearbox are arranged coaxially with each other. Furthermore, preferably, the second electric motor and the second partial gearbox are arranged coaxially with each other.

[0040] According to an alternative embodiment of the drive device, the two electric motors and the two partial gearboxes are arranged coaxially to the pedal crank shaft. In this case, the drive device is constructed in a radially nested configuration. Preferably, the first electric motor is designed as an internal rotor and the second electric motor as an external rotor.

[0041] Preferably, the second gear element of the first sub-gearbox has a first toothed section, and the gear element of the second sub-gearbox, which is operatively connected to it (i.e., the second gear element according to the first aspect of the invention or the third gear element according to the second aspect of the invention), has a second toothed section, wherein the first and second toothed sections mesh with each other. The first and second toothed sections form a first coupling drive between the sub-gearboxes. Accordingly, the gear elements operatively connected to each other via the toothed sections rotate in opposite directions relative to each other. This can be reversed, if necessary, by a further spur gear stage configured to reverse the direction of rotation.

[0042] In this sense, the second gear element of the second sub-gearbox can have a third tooth and the output gear a fourth tooth, with the third and fourth teeth meshing with each other. Thus, a further reversal of the direction of rotation occurs at the output of the drive device. The third and fourth teeth form a second coupling mechanism.

[0043] Preferably, the output gear is arranged coaxially with the crankshaft. The crankshaft can pass axially through the output gear. The concentric design saves significant axial installation space.

[0044] In an alternative embodiment, the second gear element of the first sub-gearbox and the gear element of the second sub-gearbox connected to it, i.e., the second gear element according to the first aspect of the invention or the third gear element according to the second aspect of the invention, are directly operatively connected to each other via a traction drive as the first coupling drive. Accordingly, in contrast to a spur gear stage as described above, there is no reversal of the direction of rotation, with both the second gear element of the first sub-gearbox and the gear element of the second sub-gearbox connected to it rotating in the same direction.

[0045] According to this variant, the output gear can be arranged coaxially to the second electric motor and thus parallel to the crankshaft. Furthermore, the output gear is preferably arranged parallel to the first electric motor and the first gearbox. Both the first electric motor and the first gearbox can be arranged concentrically.

[0046] According to a third aspect of the invention, a bicycle comprises a drive device according to the first or second aspect of the invention. The bicycle can be propelled solely by the muscle power of a user or cyclist. Alternatively, the bicycle can be an electric bicycle, pedelec, or e-bike, in which the bicycle's propulsion can be assisted or performed by at least one electric motor. In this case, the electric motor typically assists the user's power output according to the rider's input and a torque supplied by the user. Therefore, the term "bicycle" encompasses not only bicycles propelled solely by muscle power without a motor, but also bicycles with an additional drive system. In particular, the term "bicycle" also includes cargo bikes with more than two wheels, especially those with three or four wheels.

[0047] The aforementioned drive device can be arranged as a type of central drive in the area of ​​the crank axle. Preferably, the housing of the drive device is located between a seat tube and a down tube of the frame. The housing can be an integral part of the bicycle frame or bolted to the bicycle frame.

[0048] Naturally, the partial gear units of the drive device according to the second aspect of the invention can also be designed as eccentric gear units or other planetary gear units with three inputs or outputs. Likewise, the partial gear units of the drive device according to the first aspect of the invention can also be designed as wave gear units or other planetary gear units with three inputs or outputs.

[0049] Further measures improving the invention are described in more detail below, together with a description of four exemplary embodiments of the invention, with reference to the figures, wherein identical or similar components are provided with the same reference numeral. This shows Fig. 1 a highly schematic representation of a bicycle according to the invention with a drive device according to a first embodiment, Fig. 2 a schematic longitudinal sectional view of the drive device according to the invention Fig. 1, Fig. 3 a schematic longitudinal sectional view of the drive device according to the invention in a second embodiment, Fig. 4 a schematic longitudinal sectional view of the drive device according to a third embodiment according to the invention, and Fig. 5 a schematic longitudinal section view of the drive device according to the invention in a fourth embodiment.

[0050] Fig. Figure 1 shows a highly simplified version of a bicycle 1 according to the invention. The bicycle 1 has a frame 20 on which a steerable first wheel 21, designed as a front wheel, and a second wheel 22, designed as a drive wheel or rear wheel, are mounted. The first wheel 21 can be manually pivoted by the user via a handlebar 23, on which the user can support and hold themselves using handlebar grips while riding, the handlebar 23 being connected to the first wheel 21 via a fork 24.

[0051] A drive device 2 is integrated into a housing 3 between a seat tube 25, a down tube 26, and two frame segments 31 of the frame 20 that rotate and support the second wheel 22. The design and function of the drive device 2 are described in various embodiments according to the Fig. 2, Fig. 3, Fig. 4 to Fig. 5 is described in more detail. The housing 3 can be screwed to the frame 20 and is sealed to the outside.

[0052] After Fig. 2 to Fig. The drive device 2 is provided for a bicycle 1 that can be propelled both by the user's muscle power and with electrical assistance. The user, seated on the saddle 27, can apply drive power to the drive device 2 by pedaling 28, which is connected to a crankshaft 19 of the drive device 2 via respective crank arms. Two motor-gearbox units 4, 5, each comprising an electric motor 18, 49 and a partial gearbox 6, 7, are provided. One motor-gearbox unit 4, 5 is for power assistance for the user, and the other motor-gearbox unit 5, 4 is for implementing an e-CVT function. The drive device 2 is arranged as a mid-drive motor in the area of ​​the crankshaft 19. Thus, the bicycle 1 is designed as an e-bike. The motor-gearbox units 4, 5 are effectively arranged in the housing 3 of the drive device 2.

[0053] The first electric machine 18 comprises a stator 47 fixed in a housing and a rotor 48 rotatably arranged therewith. The second electric machine 49 comprises a stator 50 also fixed in a housing and a rotor 51 rotatably arranged therewith.

[0054] The output of the drive device 2 is a driven gear 8, which is rotationally fixed to an output shaft 9. This driven gear transmits the drive power via a chain 29 as a traction element to a sprocket 30 on the second wheel 22 to drive this rear wheel. The driven gear 8, the chain 29, and the sprocket 30 thus form a traction drive for driving the rear wheel, with the driven gear 8 and the sprocket 30 each being designed as a sprocket.

[0055] In the Fig. 2, Fig. 3, Fig. 4 to Fig. 5 different design variants of the drive device 2 are shown in more detail and are described below.

[0056] According to the first embodiment, Fig. 2 The pedal crankshaft 19 is arranged coaxially to the first motor-gearbox unit 4, consisting of the first electric machine 18 and the first sub-gearbox 6, wherein the second motor-gearbox unit 5, consisting of the second electric machine 49 and the second sub-gearbox 7, is arranged axially parallel to it. In the present case, the second electric machine 49 and the second sub-gearbox 7 are also arranged coaxially.

[0057] The E-CVT function is implemented by means of the first motor-gearbox unit 4, while the second motor-gearbox unit 5 is intended for drive support.

[0058] Each sub-gearbox 6, 7 is an eccentric gear unit, comprising an eccentric shaft 10a, 10b as the input shaft of the respective sub-gearbox 6, 7, a first eccentric gear 11a, 11b and a second eccentric gear 12a, 12b, which are arranged via an eccentric 15a, 15b, 16a, 16b rotatably mounted on a planet carrier 13a, 13b. The eccentric gears 11a, 11b, 12a, 12b and the eccentrics 15a, 15b, 16a, 16b are arranged axially spaced on the planet carrier 13a, 13b. Depending on their angular position, the eccentric gears 11a, 11b, 12a, 12b mesh with either a sun gear 17a, 17b, 32a, 32b or a ring gear 33a, 33b of the respective sub-gearbox 6, 7. The eccentric gears 11a, 11b, 12a, 12b of the respective sub-gearbox 6, 7 have the same diameter and the same number of teeth.

[0059] In this case, the sun gears 17a, 17b, 32a, 32b are non-rotatably connected to the associated eccentric shaft 10a, 10b of the respective sub-gearbox 6, 7, with the respective eccentric shaft 10a, 10b being non-rotatably connected to the rotor 48, 51 of the respective electric machine 18, 49. The eccentric shafts 10a, 10b with the sun gears 17a, 17b, 32a, 32b arranged thereon each form a first gear element of the respective sub-gearbox 6, 7 and are operatively connected to the associated electric machine 18, 49. The two sun gears 17a, 17b, 32a, 32b of the respective sub-gearbox 6, 7 have different diameters and numbers of teeth.

[0060] The planet carriers 13a, 13b each form a second gear element of the respective sub-gearbox 6, 7 and are operatively connected to each other via a first coupling drive 34 in the form of a spur gear stage. The second gear element of the first sub-gearbox 6, here the first planet carrier 13a, has a first tooth 35 and the operatively connected second gear element of the second sub-gearbox 7, here the second planet carrier 13b, has a second tooth 36, wherein the first and second tooth 35, 36 are in meshing with each other, and the planet carriers 13a, 13b rotate accordingly in opposite directions.

[0061] The ring gear 33a, 33b of the respective sub-gearbox 6, 7 is to be understood as the third gear element of the respective sub-gearbox 6, 7. The first ring gear 33a of the first sub-gearbox 6 represents the gear output and is directly and rotationally fixed to the output shaft 9 and the driven gear 8. The second ring gear 33b of the second sub-gearbox 7 is fixed to the housing 3 of the drive device 2.

[0062] A freewheel 14 is arranged between the crankshaft 19 and the second gear element of the first sub-gearbox 6, i.e., the first planet carrier 13a. A torque can be transmitted from the crankshaft 19 to the first planet carrier 13b of the first sub-gearbox 6 via the freewheel 14. The freewheel 14 is designed as a friction-fit ball freewheel, which is configured to allow the crankshaft 19 to rotate freely in one direction while transmitting a torque in the opposite direction. Thus, a torque is transmitted via the freewheel 14 to the first planet carrier 13b of the first sub-gearbox 6 only in one direction of rotation of the crankshaft 19.

[0063] The freewheel 14 serves two purposes: firstly, to dampen vibrations that can be caused by the partial gear units 6, 7 and the electric motors 18, 49; and secondly, to allow the rider to pedal backwards with little or no resistance, as the motor-gearbox units 4, 5 are mechanically decoupled from the crank axle 19 by the freewheel 14 when pedaling backwards. Furthermore, when the rider quickly stops the cranks or the crank axle 19, they are not driven further by the inertia of the drive components of the motor-gearbox units 4, 5. This improves the riding experience for the cyclist.

[0064] A torque generated by muscle power can be introduced into the drive device 2 via the crankshaft 19 and transmitted via the freewheel 14 to the first planet carrier 13a of the first motor-gearbox unit 4. When the crankshaft 19 is stationary, i.e., when the cyclist is not pedaling, the freewheel 14 prevents the crankshaft 19 from being driven by the inertia of the first motor-gearbox unit 4.

[0065] By varying the speed and direction of rotation of the first electric motor 18, which, together with the first sub-gearbox 6, performs the E-CVT function, it is possible to switch between operating modes and to continuously adjust the gear ratio. If the first electric motor 18 is controlled so that the first rotor 48 is driven at the same speed as the pedal crank shaft 19, the first sub-gearbox 6 is in block rotation, i.e., with a 1:1 gear ratio, between the first planet carrier 13a and the first ring gear 33a of the first sub-gearbox 6. Consequently, the output gear 8 rotates at the same speed as the pedal crank shaft 19. If the first rotor 48 rotates or is driven more slowly than the pedal crank shaft 19, the first ring gear 33a of the first sub-gearbox 6, and thus the output or output gear 8, is also driven more slowly than the pedal crank shaft 19.If the first rotor 49 rotates faster than the pedal crankshaft 19, the first ring gear 33a of the first partial gearbox 6, and thus the output gear 8, are also driven faster than the pedal crankshaft 19. Due to the gear ratio of the first partial gearbox 6, the first electric machine 18 only needs to provide a torque lower than that of the pedal crankshaft 19 by the gear ratio factor, but at a correspondingly higher rotational speed.

[0066] However, reverse travel can be achieved if the first rotor 48 is driven backwards at a faster speed beyond the point where the output or the output wheel 8 has come to a standstill. In this case, the output wheel 8 rotates backwards when the pedal crank shaft 19 is driven normally in the forward direction.

[0067] The second motor-gearbox unit 5 takes on the task of providing additional torque, analogous to electric motors in conventional e-bike drives.

[0068] In the present case, the two motor-gearbox units 4, 5 are essentially identical in design. The output of the second motor-gearbox unit 5 is via the first coupling drive 34 between the two planet carriers 13a, 13b, with the torque support on the housing 3 or a housing part of the housing 3 being provided via the second ring gear 33b of the second sub-gearbox 7.

[0069] In this embodiment, the output wheel 8, the pedal crank shaft 19 and the first motor-gearbox unit 4 are arranged concentrically.

[0070] Fig. Figure 3 shows a second embodiment of the drive device 2 according to the invention. Unless otherwise stated, with regard to Fig. 3. The explanations regarding the first embodiment according to Fig. 1 and Fig. 2 referred.

[0071] In contrast to the embodiment according to Fig. In the drive device 2, the eccentric gear is replaced by a wave gear, so that each sub-gearbox 6, 7 is a wave gear. Each wave gear comprises a flexible ring element 38a, 38b, which is deformable at least partially in the radial direction and is actuated by a rotatably driven wave generator 37a, 37b as the first gear element of the respective sub-gearbox 6, 7, and which has external teeth as the second gear element of the respective sub-gearbox 6, 7, and a rigid ring element 39a, 39b with internal teeth as the third gear element of the respective sub-gearbox 6, 7, wherein the internal teeth of the rigid ring element 39a, 39b engage with the external teeth of the flexible ring element 38a, 38b at at least one tooth engagement area 40 to transmit a torque.

[0072] The respective wave generator 37a, 37b of the respective sub-gearbox 6, 7 is operatively connected to the rotor 48, 51 of the respective electric machine 18, 49 via an associated input shaft 41a, 41b. The first flexible ring element 38a of the first sub-gearbox 6 is operatively connected to the pedal crank shaft 19 via a freewheel 14 and to the second rigid ring element 39b of the second sub-gearbox 7 via a first coupling drive 34. A first gear 44 with a first tooth 35 is provided on the first flexible ring element 38a of the first sub-gearbox 6. A second tooth 36 is formed on the operatively connected second rigid ring element 39b of the second sub-gearbox 7. The first and second tooth 35, 36 mesh with each other. Accordingly, the direction of rotation of the components meshing with each other is reversed via the first coupling drive 34.The first rigid ring element 39a of the first partial gearbox 6 is fixed to the housing 3.

[0073] The output of the drive device is formed by the second flexible ring element 38b of the second sub-gearbox 7, which is operatively connected to the output gear 8 via a second coupling drive 42. The second flexible ring element 38b of the second sub-gearbox 7 has a third tooth 43, and a second gear 46 with a fourth tooth 45 is arranged on the output shaft 9, with the third and fourth teeth 43 and 45 meshing with each other. Accordingly, the direction of rotation of the meshing components is reversed again via the second coupling drive 42.

[0074] In contrast to the embodiment according to Fig. 2 In this embodiment, the first and second electric machines 18, 49 perform reversed functions. In other words, the first motor-gearbox unit 4 provides drive support, while the second motor-gearbox unit 5 implements the E-CVT function. Thus, the motor for the E-CVT function and the support motor are interchanged.

[0075] The pedals 28, the crankshaft 19, and the freewheel 14 initially drive the first gear 44 of the first coupling drive 34, through which torque is transmitted to the second motor-gearbox unit 5. In this case, the second rigid ring element 39b is driven directly via the first coupling drive 34. The second rigid ring element 39b, together with the second flexible ring element 38b, acts on the second shaft generator 37b.

[0076] By varying the rotational speed of the second electric machine 49 or the second rotor 51, the gear ratio between the pedal crank shaft 19 and the output gear 8 can be continuously varied up to negative gear ratios, as described above. For further details, please refer to the explanations regarding Fig. 2 referenced, which are applicable here by analogy.

[0077] The first electric motor 18 provides motorized drive support. By mounting the first rigid ring element 39a on a frame-mounted support, a significantly increased torque relative to the torque of the first electric motor 18 can be drawn from the first flexible ring element 38a. For this purpose, it is connected in parallel to the first coupling drive 34 and thus acts on it like the pedal crank shaft 19 via the freewheel 14.

[0078] In this embodiment, the output gear 8, the pedal crankshaft 19, and the first motor-gearbox unit 4 are arranged concentrically. Thus, the first electric machine 18 and the first partial gearbox 6 are arranged coaxially with the pedal crankshaft 19 and the output gear 8.

[0079] Fig. Figure 4 shows a third embodiment of the drive device 2 according to the invention. The third embodiment according to Fig. 4 is an alternative embodiment to the second embodiment according to Fig. 3. Unless otherwise stated, regarding Fig. 4 to the explanations regarding the second embodiment according to Fig. 3 referred.

[0080] The difference here lies solely in the design of the first coupling drive 34 and the design of the output of the drive device 2.

[0081] In order to further reduce the overall width of the drive device 2, in addition to the already relatively compact wave gear, or to make the drive device 2 even more axially compact, according to Fig. 4. The output of the drive device 2 is not connected via a second coupling drive analogous to Fig. 3 is not led back to the axially parallel pedal crankshaft 19, but the drive power is led directly concentrically out of the housing 3 to the second motor-gearbox unit 5. This allows the second coupling drive 42 to be connected according to Fig. 3 can be omitted, thereby saving axial installation space.

[0082] Since a uniform direction of rotation of the crankshaft 19 and the output gear 8 is desirable for bicycle applications, the first coupling drive 34 is also designed as a traction drive. A first traction gear 52 is fixedly mounted on the first flexible ring element 38a, and a second traction gear 53 is fixedly mounted on the second rigid ring element 39b. These gears are operatively connected to each other via a traction element, such as a chain or belt. The traction gears 52 and 53, which are corresponding belt pulleys or sprockets, thus rotate in the same direction, and no reversal of the direction of rotation occurs. A three-shaft design with intermediate gears on an intermediate shaft is also possible to avoid a reversal of the direction of rotation.

[0083] In an alternative embodiment not shown here, compared to the second and third embodiments according to Fig. 3 or Fig. 4. The output of the first motor-gearbox unit 4, which is intended for drive support, can be directly coupled to the output gear 8. While this simplifies the design of the drive device 2, it does not allow for varying the drive power of the first electric machine 18, i.e., its speed and torque, via the second motor-gearbox unit 5, which acts as an E-CVT. Only the drive power generated by muscle power can then be continuously varied.

[0084] It is of course conceivable to interchange the connections of the gear elements of the respective sub-gearboxes 6, 7. For example, the connection of the respective flexible ring element 38a, 38b can be interchanged with the respective rigid ring element 39a, 39b. Since interchanging the connection of the respective flexible ring element 38a, 38b and the associated rigid ring element 39a, 39b has hardly any effect on the achievable high gear ratio of the respective wave gear, both connection variants are conceivable and equally possible. This allows the drive device 2 to be flexibly adapted to wave gear types already available or desired by the customer and / or supplier.

[0085] Fig. Figure 5 shows a fourth embodiment of the drive device 2 according to the invention. The fourth embodiment according to Fig. 5 is an alternative embodiment to the second and third embodiments according to Fig. 3 or Fig. 4. Unless otherwise stated, therefore, with regard to Fig. 5. Refer to the explanations regarding the exemplary embodiment according to Fig. 3 or Fig. 4 referred.

[0086] In this embodiment, the two motor-gearbox units 4, 5 are arranged concentrically and radially nested. The first electric machine 18 and the first sub-gearbox 6 are arranged radially within the second electric machine 49 and the second sub-gearbox 7, respectively. The two electric machines 18, 49 are arranged axially essentially in a first common radial plane, and the two sub-gearboxes 6, 7 are arranged axially essentially in a second common radial plane. The radially extending planes are arranged axially adjacent to each other. The two electric machines 18, 49 and the two sub-gearboxes 6, 7 are arranged coaxially with the pedal crankshaft 19 and the output gear 8.

[0087] The radially inner first electric motor 18 is designed as an internal rotor and is intended for drive support, while the radially outer second electric motor 49 is designed as an external rotor and is intended for the implementation of the E-CVT function, i.e., for stepless transmission adjustment from overdrive to reverse gear as described above. The first partial transmission 6 allows the high speeds of the first electric motor 18 to be converted into speeds within the range of normal pedal crank speeds during normal driving operation, particularly in the range between i=20 and i=50.

[0088] In this embodiment, the wave generators 37a, 37b are each understood as the first gear element of the respective sub-gearbox 6, 7, which are each operatively connected to an input shaft 41a, 41b or the respective rotor 48, 51. The first flexible ring element 38a is understood as the second gear element of the first sub-gearbox 6. The first rigid ring element 39a is understood as the third gear element of the first sub-gearbox 6 and is fixed to the housing 3. The second rigid ring element 39b is understood as the second gear element of the second sub-gearbox 7 and is rotationally fixed to the output gear 8 via the output shaft 9. The second flexible ring element 38b is understood as the third gear element of the second sub-gearbox 7.In the present case, the second gear element of the first sub-gearbox 6, i.e. the first flexible ring element 38a, is connected to the third gear element of the second sub-gearbox 7, i.e. the second flexible ring element 38b, in a rotationally fixed manner and is operatively connected to the pedal crank shaft 19 via a freewheel 14.

[0089] The freewheel 14 transmits a torque to the flexible ring elements 38a, 38b when the pedal crank shaft 19 is rotated in the direction of forward travel, and is overrun when the pedal drive is reversed. The pedal crank shaft 19 is guided centrally through the housing 3 and connected to pedals 28 on both sides for drive by the rider via pedal cranks.

[0090] The advantage of this design, besides its compactness, is the possibility of easily coupling the two electric machines 18, 49 with power electronics (not shown here) and, if necessary, sensors, which can be arranged on the same side of the electric machines 18, 49, facing away from the partial gear sets 6, 7. Thus, the power electronics of the first electric machines 18, 49

[0091] A further advantage for bicycle applications is that the concentric arrangement on a common axis eliminates the need for additional gear stages. Consequently, the drive device 2 has a simple design. With such a drive device 2, a simpler, more compact, and lighter construction of the drive device 2 can therefore be achieved. Reference symbol list 1 bicycle 2 Drive device 3 cases 4 First engine-transmission unit 5 Second engine-transmission unit 6 First sub-transmission 7 Second sub-transmission 8 Output wheel 9 Output wave 10a, 10b Eccentric shaft 11a, 11b First eccentric wheel 12a, 12b Second eccentric wheel 13a, 13b Planetary carrier 14 Free run 15a, 15b First eccentric 16a, 16b Second eccentric 17a, 17b First sun wheel 18 First electric machine 19 Crankshaft 20 frames 21 First wheel 22 Second wheel 23 handlebars 24 Fork 25 seat tube 26 down tube 27 saddles 28 Pedal 29 chain 30 toothed ring 31 frame segment 32a, 32b Second sun wheel 33a, 33b Ring gear 34 First coupling drive 35 First gearing 36 Second gearing 37a, 37b Wave generator 38a, 38b Flexible ring element 39a, 39b Rigid ring element 40 Tooth engagement area 41a, 41b Input wave 42 Second coupling drive 43 Third Interlocking 44 First gear 45 Fourth gear 46 Second gear 47 Stator of the first electric machine 48 Rotor of the first electric machine 49 Second electric machine 50 Stator of the second electric machine 51 Rotor of the second electric machine 52 First traction wheel 53 Second traction wheel

Claims

[1] Drive device (2) for a bicycle (1), comprising a pedal crank shaft (19), a first electric machine (18), a first partial transmission (6), a second electric machine (49), and a second partial transmission (7), wherein a first transmission element of the first partial transmission (6) is operatively connected to the first electric machine (18), wherein a second transmission element of the first partial transmission (6) is operatively connected to a second transmission element of the second partial transmission (7), wherein a third transmission element of the first partial transmission (6) is operatively connected to an output gear (8), wherein a first transmission element of the second partial transmission (7) is operatively connected to the second electric machine (49), and wherein a third transmission element of the second partial transmission (7) is fixed to a housing (3), and wherein a freewheel (14) is arranged between the pedal crank shaft (19) and the second transmission element of the first partial transmission (6), characterized by, that either both sub-gearboxes (6, 7) are a wave gear or both sub-gearboxes (6, 7) are an eccentric gear. [2] Drive device (2) for a bicycle (1), comprising a pedal crank shaft (19), a first electric machine (18), a first partial transmission (6), a second electric machine (49), a second partial transmission (7), wherein a first transmission element of the first partial transmission (6) is operatively connected to the first electric machine (18), wherein a second transmission element of the first partial transmission (6) is operatively connected to a third transmission element of the second partial transmission (7), wherein a third transmission element of the first partial transmission (6) is fixed to a housing (3), wherein a first transmission element of the second partial transmission (7) is operatively connected to the second electric machine (49), and wherein a second transmission element of the second partial transmission (7) is operatively connected to an output gear (8), and wherein a freewheel (14) is arranged between the pedal crank shaft (19) and the second transmission element of the first partial transmission (6). [3] Drive device (2) according to claim 1 or claim 2, characterized by , that each sub-gearbox (6, 7) is an eccentric gearset designed as a planetary gearset, each comprising a first eccentric wheel (11a, 11b) and a second eccentric wheel (12a, 12b) which are arranged on the second gear element of the respective sub-gearbox (6, 7) via an eccentric (15a, 15b, 16a, 16b) rotatably arranged on the second gear element of the respective sub-gearbox (6, 7). [4] Drive device (2) according to claim 1 or claim 2, characterized by, that each partial transmission (6, 7) is a wave transmission, each comprising a flexible ring element (38a, 38b) with external teeth, which can be actuated by a wave generator (37a, 37b) and is at least partially deformable in the radial direction, and a rigid ring element (39a, 39b) with internal teeth, wherein the internal teeth of the rigid ring element (39a, 39b) engage with the external teeth of the flexible ring element (38a, 38b) for the transmission of a torque at at least one tooth engagement area (40). [5] Drive device (2) according to one of the preceding claims, characterized by , that the first electric machine (18) and the first partial gearbox (6) are arranged coaxially to the pedal crank shaft (19) and / or that the second electric machine (49) and the second partial gearbox (7) are each arranged axially parallel to the pedal crank shaft (19). [6] Drive device (2) according to claim 2 in conjunction with claim 4, characterized by , that the two electric machines (18, 49) and the two partial gearboxes (6, 7) are arranged coaxially to the pedal crank shaft (19). [7] Drive device (2) according to any one of claims 1 to 5, characterized by , that the second gear element of the first sub-gearbox (6) has a first toothing (35) and the gear element of the second sub-gearbox (7) connected to it has a second toothing (36), wherein the first and second toothing (35, 36) are in tooth mesh with each other. [8] Drive device (2) according to claim 7 in conjunction with claim 2 and claim 4, characterized by , that the second gear element of the second sub-gearbox (7) has a third tooth (43) and the output gear (8) has a fourth tooth (45), wherein the third and fourth teeth (43, 45) are in tooth mesh with each other. [9] Drive device (2) according to any one of claims 1 to 5, characterized by, that the second gear element of the first sub-gearbox (6) and the gear element of the second sub-gearbox (7) connected to it are directly connected to each other via a traction drive. [10] Bicycle (1) comprising a drive device (2) according to any of the preceding claims.

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