Electric drive unit for a bicycle and bicycle having the same

Abstract

The invention relates to an electric drive (1; 11; 21; 31) for a bicycle, with a gear mechanism (4). The gear mechanism comprises a planetary gear set. The planetary gear set comprises at least three rotating elements (12; SR, PT, HR) arranged rotatably relative to one another. The electric drive (1; 11; 21; 31) further comprises an electric motor (5), a drive shaft (7; 7'), a drive wheel (8) for transmitting the motor force of the electric motor to the drive shaft, a first freewheel element (F1) and a second freewheel element (F2). The drive wheel can be connected to the drive shaft (7; 7') by means of the first freewheel element. One rotating element of the gear mechanism can be connected to the drive shaft by means of the second freewheel element. Another rotating element of the rotating elements of the planetary gear set of the gear mechanism is formed integrally with the power transmission (7; 7'; 9) of the gear mechanism.

Description

[Technical field]

[0001] The present invention relates to an electric drive for a bicycle. The present invention also relates to a bicycle having such an electric drive.

[0002] Electrically assisted bicycles (pedelecs) are known in which electric bicycles are driven in a hybrid manner, in particular electrically by means of an electric motor and by muscle power by means of pedals. These have an electric motor arranged in the receiving area of ​​the pedal shaft of the electric bicycle. The gear mechanism which transmits the torque from the electric motor and the pedals of the electric bicycle to the drive shaft of the electric bicycle is also arranged in the receiving area of ​​the pedal shaft of the electric bicycle. However, the amount of installation space in the vicinity of the receiving area of ​​the pedal shaft of the electric bicycle is limited. Summary of the Invention

[0003] In a first aspect, the invention relates to an electric drive for a bicycle. The drive can be designed to transmit an electrically generated drive force to a drive axle of the bicycle. Alternatively or additionally, the drive can be designed to transmit a drive force generated by muscle power, for example by rotation of the bicycle pedals, to the drive axle of the bicycle. For example, the drive can be used to generate a torque that is transmitted to the drive axle of the bicycle to drive the bicycle. The drive can have a hybrid design, i.e. the drive can also be designed such that the bicycle is driven both electrically and by muscle power. The bicycle can also be an electric bicycle, in particular a hybrid drive pedelec. In the case of a pedelec, the bicycle drive force generated by muscle power and the bicycle drive force generated electrically can be combined.

[0004] The electric drive comprises a gear mechanism arranged at a bottom bracket of the bicycle. The bottom bracket can be the part of the bicycle frame where the pedals for driving the bicycle are arranged. The housing of the bottom bracket can be designed in the form of a pipe to which the bicycle pedals are attached. The gear mechanism can also be attached to the housing. Furthermore, a chain ring can be arranged in the area of ​​the bottom bracket, which can be designed to transmit the driving force generated by the drive to a driving axle of the bicycle. The gear mechanism can be designed to convert, by means of various conversion elements, the driving force generated by the drive and applied in the form of a driving speed into an output speed acting on the drive shaft.

[0005] The gear mechanism comprises at least one planetary gear set. The planetary gear set comprises at least three rotating elements. The rotating elements are arranged rotatably relative to one another and are designed to transmit torque. The three rotating elements arranged rotatably relative to one another can be a sun gear, a planet carrier with at least one planetary gear, and an internal gear of the planetary gear set. The sun gear, the planet carrier, and the internal gear can each be arranged on a rotatably mounted shaft. The sun gear, the planet gear, and the internal gear can each be designed as gears that mesh with one another. Depending on the diameter of the individual gears and their relative rotation speeds, torque can be transmitted between the sun gear, the planet carrier, and the internal gear. For example, the internal gear can be fixed, preventing it from rotating. The sun gear can be coupled to a drive shaft of the bicycle. The planet carrier can be coupled to a pedal crankshaft of the bicycle. As both the sun gear and the internal gear mesh with the planet carrier, torque can be transmitted from the drive to the drive shaft of the bicycle.

[0006] Furthermore, the electric drive comprises an electric motor offset with respect to the gear mechanism and at least a drive shaft mounted on the pedal crankshaft of the bicycle. The electric motor can be designed to convert electrical energy into mechanical energy. The electric motor can be designed, for example, as a synchronous or asynchronous motor. The output shaft of the electric motor can be connected, for example, in a permanently non-rotatable manner, with the rotor of the electric motor. The electric motor can be arranged, for example, axially parallel to the longitudinal axis of the gear mechanism or the bottom bracket. The pedal crankshaft can be a mechanical shaft mounted along the longitudinal direction of the bottom bracket. The pedal crankshaft can have at least one end protruding from the bottom bracket. At both ends of the pedal crankshaft, a pedal crank can be mounted, on which a pedal for mechanically driving the bicycle can be mounted, respectively. The drive shaft can be designed in the form of a hollow shaft, which is mounted on the pedal crankshaft so as to be mechanically operatively connected to the pedal crankshaft. The drive force generated by the pedal crank can be transmitted to the drive shaft in the form of a torque via the pedal crankshaft. The drive shaft may further be mechanically operably connected to at least one rotating element of a planetary gear set of the gear mechanism. The drive shaft may further be mechanically operably connected to an output shaft of the electric motor.

[0007] Furthermore, the electric drive comprises a drive wheel, which is arranged coaxially with the drive shaft and transmits the motor force from the electric motor to the drive shaft. The drive wheel can be designed in the form of a gear that can be coupled to the output shaft of the electric motor via a traction device. The traction device can be a chain or a toothed belt that can mesh with the teeth of the gear. Alternatively or additionally, the drive wheel can be a pulley that can be connected to the traction device in a frictionally coupled manner.

[0008] In addition, the electric drive comprises a first freewheel element and a second freewheel element. The first freewheel element and the second freewheel element are arranged together in a one-piece freewheel element carrier. The first freewheel element can be designed to couple two components of the drive depending on the direction of rotation. The first freewheel element can thus be designed to couple two components of the drive for the transmission of torque in a first direction. In a second direction of rotation opposite to the first direction of rotation, the first freewheel element can be used to release or interrupt the connection between the two components. For example, the first freewheel element can be used to block a shaft from rotating in the first direction inside the drive. What has been said about the first freewheel element also applies to the second freewheel element. Thus, the coupling function depending on the direction of rotation of the two components of the drive can be realized using the first or the second freewheel element. The first and second freewheel elements can have pawls. Alternatively, the first and second freewheel elements can have clamping rollers, clamping bodies, pawl rings or wrap springs. The first and second freewheel elements are arranged together in a one-piece freewheel element carrier, the freewheel element carrier therefore being a single component in which the first freewheel element and the second freewheel element are respectively partially arranged.

[0009] The drive wheel can be connected to the drive shaft by means of a first freewheel element via a one-piece freewheel element carrier. Furthermore, one of the rotating elements of the planetary gear set of the gear mechanism can be connected to the drive shaft by means of a second freewheel element via a one-piece freewheel element carrier. The first freewheel element can thus couple the drive wheel or the drive shaft connected thereto with the drive shaft depending on the direction of rotation. The second freewheel element can thus couple one of the rotating elements of the planetary gear set of the gear mechanism, e.g. an internal gear, with the drive shaft depending on the direction of rotation. The one-piece freewheel element carrier allows these two coupling functions to be realized via a single component.

[0010] Another rotating element of the rotating elements of the planetary gear set of the gear mechanism is formed integrally with the gear mechanism transmission. The other rotating element of the planetary gear set can be, for example, a sun gear. Meanwhile, the internal gear of the planetary gear set can be connectable with the drive shaft by means of a second freewheel element via a one-piece freewheel element carrier. The gear mechanism transmission can be a transmission component arranged inside the gear mechanism, for example rotatable, for transmitting torque. Alternatively, the gear mechanism transmission can be a plurality of transmission components arranged inside the gear mechanism, in particular rotatable, for transmitting torque to each other.

[0011] Thus, according to the proposed electric drive for bicycles, both the freewheel element carrier itself and the further rotating element of the planetary gear set are formed integrally with the power transmission of the gear mechanism. This allows the number of components to be reduced. Furthermore, it is possible to reduce the required installation space inside the bottom bracket, since fewer components need to be accommodated inside the bottom bracket. In addition, the drive can also be designed more simply and cost-effectively, since fewer components have to be used.

[0012] According to one embodiment of the drive device, the power transmission of the gear mechanism can be formed by the drive shaft. Thus, in this embodiment, one of the rotating elements of the planetary gear set of the gear mechanism can be connected to the drive shaft by means of a second freewheel element via a one-piece freewheel element carrier. Another rotating element of the planetary gear set of the planetary gear mechanism can be formed integrally with the drive shaft. Thus, in particular in the design of the gear mechanism, the number of components can be reduced, such as components such as teeth between the drive shaft and the rotating elements of the planetary gear set. Furthermore, due to the integral design, i.e. the direct connection between one of the rotating elements of the planetary gear set and the drive shaft, friction losses during the transmission of torque between these components can also be minimized.

[0013] According to another embodiment of the drive, the power transmission of the gear mechanism can be formed by a one-piece freewheel element carrier. In this embodiment, the one-piece freewheel element carrier can thus be formed integrally with the rotating elements of the planetary gear set. This makes it possible to eliminate the need for an additional freewheel element carrier between the rotating elements of the planetary gear set. The installation of the drive can therefore be made easier. In addition, this arrangement allows both the function of torque transmission and the function of connection between two components that transmit the torque to be realized by means of a single component. This allows the complexity of the gear mechanism to be reduced.

[0014] According to another embodiment of the drive device, the gear mechanism power transmission can be formed by a drive shaft and a one-piece freewheel element carrier. In this embodiment, the above-mentioned features and advantages can be combined.

[0015] According to another embodiment, the drive shaft of the bicycle can be mechanically operatively connected to at least one pedal crank. The power transmission path can be from the pedal crank to the drive shaft via a gear mechanism. The pedal crank can be attached to the pedal crankshaft, for example. In this case, the drive shaft can be mechanically operatively connected to the pedal crank via the pedal crankshaft on which the drive shaft is attached. In addition, the drive shaft can be further connected to a component of the gear mechanism via a first and / or a second freewheel element. Thus, when a driving force generated by a human pressing on a pedal attached to the pedal crank is applied to the pedal crank, the driving force can be transmitted to the drive shaft via the above-mentioned operative connection.

[0016] In this embodiment, the motor force from the electric motor can be transferred to the drive shaft in an end region of the power transmission path. The motor force from the electric motor can be transferred to the drive shaft by means of a drive wheel arranged coaxially with the drive shaft. In this embodiment, the drive wheel can be arranged inside the drive so that the motor force from the electric motor is transferred to the drive shaft at the output of the gear mechanism. Thus, the drive force applied via the pedal crank can first be led to the gear mechanism via the pedal crankshaft for torque transfer, i.e. for setting a suitable transmission ratio of the rotating elements of the planetary gear set. After the suitable transmission ratio has been set, i.e. after a gear shift has occurred, the drive force can be amplified by the motor force from the electric motor and applied to the drive shaft. This configuration offers the advantage that a gear shift can be performed without additional motor force from the electric motor, i.e. without load. This allows the service life of the gear mechanism to be extended.

[0017] According to another embodiment, the drive wheels can be mounted on the drive shaft. The drive wheels can be mounted directly on the drive shaft. Alternatively, the drive wheels can be mounted on the drive shaft indirectly, for example by means of another rotating element. The drive wheels can be mounted on the drive shaft, in particular for transmitting torque. This configuration offers the advantage that the motor power from the electric motor can be transmitted particularly simply by the drive wheels.

[0018] According to one embodiment, the drive wheels can be mounted on the housing of the drive device. By mounting the drive wheels on the housing of the drive device, installation space inside the drive device can be saved.

[0019] According to another embodiment, the first and second freewheel elements can be arranged at least partially axially adjacent to each other inside the one-piece freewheel element carrier with respect to the longitudinal axis of the drive shaft. The longitudinal axis of the drive shaft can, for example, correspond to the axis along which the drive shaft extends in the bottom bracket. The first and second freewheel elements can be arranged at least partially adjacent to each other along this axis. For example, the first and second freewheel elements can contact each other on their respective outer surfaces oriented perpendicularly to the longitudinal axis of the drive shaft. Thus, in this embodiment, the extent of the one-piece freewheel element carrier can be greater in a direction along the longitudinal axis of the drive shaft than in a direction perpendicular to this axis. Thus, in this embodiment, the installation space required in a radial direction with respect to the longitudinal axis of the drive shaft can be reduced.

[0020] According to another embodiment, the first and second freewheel elements can be arranged at least partially radially adjacent to one another inside the one-piece freewheel element carrier with respect to the longitudinal axis of the drive shaft. The longitudinal axis of the drive shaft can, for example, correspond to the axis along which the drive shaft extends in the bottom bracket. The first and second freewheel elements can extend radially outward from this axis and be arranged at least partially adjacent to one another. Thus, in this embodiment, the extent of the one-piece freewheel element carrier can be greater in a direction perpendicular to the longitudinal axis of the drive shaft than in a direction parallel to this axis. As a result, in this embodiment, the installation space required in the axial direction with respect to the longitudinal axis of the drive shaft can be reduced.

[0021] According to another embodiment, the first and second freewheel elements can be oriented in the same direction inside the one-piece freewheel element carrier with respect to the longitudinal axis of the drive shaft. For example, the first and second freewheel elements can be designed as first and second claws. The first and second claws can be oriented such that the claws can extend at least partially radially outward inside the one-piece freewheel carrier element with respect to the longitudinal axis of the drive shaft. Alternatively, the first and second claws can extend radially inward with respect to the longitudinal axis of the drive shaft. Further configurations of the first and second freewheel elements and their respective orientations are also conceivable. This embodiment provides the advantage that the first and second freewheel elements can be easily formed inside the one-piece freewheel element carrier, in particular in the same direction.

[0022] According to another embodiment, the first and second freewheel elements can be oriented in opposite directions inside the one-piece freewheel element carrier with respect to the longitudinal axis of the drive shaft. For example, the first and second freewheel elements can be designed as first and second claws. The first and second claws can be oriented inside the one-piece freewheel element carrier such that the first claw can extend at least partially radially outward with respect to the longitudinal axis of the drive shaft. The second claw can extend at least partially radially inward with respect to the longitudinal axis of the drive shaft. Further configurations of the first and second freewheel elements and their respective orientations are also conceivable. This embodiment offers the advantage that the first and second freewheel elements can be easily formed inside the one-piece freewheel element carrier, in particular as mirror images in the axial direction.

[0023] According to another embodiment, the first and second freewheel elements can be arranged inside the one-piece freewheel element carrier at a predetermined distance from the longitudinal axis of the drive shaft. The predetermined distance of the one-piece freewheel element carrier from the longitudinal axis of the drive shaft can be determined or defined, for example, by the expected load-bearing capacity of the first and second freewheel elements. For example, if a relatively high load-bearing capacity is expected, the first and second freewheel elements can be arranged at a relatively large distance from the longitudinal axis of the drive shaft. Alternatively, if a relatively low load-bearing capacity is expected, the first and second freewheel elements can be arranged at a relatively small distance from the longitudinal axis of the drive shaft. Thus, the torque acting on the one-piece freewheel element carrier can be adjusted by appropriately selecting the distance from the longitudinal axis of the drive shaft. This allows the service life of the one-piece freewheel element carrier to be extended.

[0024] In a second aspect, the present invention relates to a bicycle comprising an electric drive according to the first aspect and two pedal cranks arranged at opposite ends of a pedal crankshaft. The pedal cranks are mechanically operatively connected to a drive shaft attached to the pedal crankshaft for human-powered driving of the bicycle. Respective other features, embodiments and advantages can be found in the description of the first aspect. Conversely, the features, embodiments and advantages of the second aspect also constitute the features, embodiments and advantages of the first aspect. [Brief description of the drawings]

[0025] [Figure 1] 2 is a schematic diagram of a detail of an electric drive device arranged in a bottom bracket of a bicycle according to an embodiment of the present invention. FIG. [Diagram 2] 4 is a schematic diagram of a detail of an electric drive arranged in a bottom bracket of a bicycle according to a further embodiment of the invention; [Figure 3a] 4 is a schematic diagram of a detail of an electric drive arranged in a bottom bracket of a bicycle according to a further embodiment of the invention; [Figure 3b] 3b shows a schematic diagram of a detail of an electric drive arranged in a bottom bracket of a bicycle according to a further development of the embodiment of FIG. 3a. [Figure 4] 4 is a schematic diagram of a detail of an electric drive arranged in a bottom bracket of a bicycle according to a further embodiment of the invention; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] Figure 1 shows diagrammatically details of an electric drive 1 arranged in a bottom bracket 3 of a bicycle, not shown in Figure 1. The drive 1 is horizontally inverted with respect to the shown figure and extends downwards. The electric drive 1 comprises a gear mechanism 4 arranged in the bottom bracket 3. The gear mechanism 4 is shown in Figure 1 as a planetary gear mechanism 4 and comprises a sun gear SR, a number of planetary gears PR arranged on a planet carrier PT, and an internal gear HR. The planetary gear mechanism 4 is arranged in a known manner by means of the sun gear SR, the planet carrier PT and the internal gear HR to transmit torque.

[0027] The drive device 1 further comprises an electric motor 5. The electric motor 5 is arranged offset relative to the gear mechanism 4 and electrically drives the bicycle. As shown in FIG. 1, the electric motor 5 is arranged axially parallel to the longitudinal axis of the gear mechanism 4. In this case, the electric motor 5 is arranged offset relative to the gear mechanism 4 relative to the plane of FIG. 1. A pedal crankshaft 6 is attached to the bottom bracket 3 of the bicycle. The pedal crankshaft 6 is mechanically operatively connected to a pedal crank, not shown in FIG. 1, and drives the bicycle by muscle power. A drive shaft 7 is attached on the pedal crankshaft 6. As shown in FIG. 1, the drive shaft 7 is designed as a hollow shaft and is attached on the pedal crankshaft 6 by means of bearings L1, L2.

[0028] To drive the bicycle electrically, the electric motor 5 is mechanically operatively connected to a drive wheel 8 arranged coaxially with the drive shaft 7. A traction device 81, i.e. a chain 81 in FIG. 1, is used to transmit the torque generated by the electric motor 5 to the drive wheel 8 and from there to the drive shaft 7. The drive wheel 8 is mounted to the drive shaft 7 by means of a ball bearing KL1.

[0029] The electric drive 1 further comprises a first freewheel element F1 and a second freewheel element F2, which are respectively indicated as first and second pawls F1, F2 in Fig. 1. The first pawl F1 and the second pawl F2 are arranged together on a one-piece freewheel element carrier 9. The one-piece freewheel element carrier 9 is a single component on which the first freewheel element F1 and the second freewheel element F2 are respectively partially arranged.

[0030] To transmit the motor power of the electric motor 5, the drive wheel 8 can be connected to the drive shaft 7 by means of a first freewheel element F1, in particular via a one-piece freewheel element carrier 9. Thus, the electric motor 5 can be coupled to the drive shaft 7 by means of the first freewheel element F1 via the one-piece freewheel element carrier 9 depending on the direction of rotation.

[0031] One of the rotating elements of the planetary gear set of the gear mechanism 4 can be connected to the drive shaft 7 by means of a second freewheel element F2, in particular via a one-piece freewheel element carrier 9. A rotating element 12 of the gear mechanism 4, which is only partially shown in Figure 1, can be connected to the drive shaft 7 via the second freewheel element F2. This rotating element 12 of the gear mechanism 4 can thus be coupled to the drive shaft 7 by means of the second freewheel element F2 via the one-piece freewheel element carrier 9, depending on the direction of rotation.

[0032] In the embodiment of FIG. 1, further rotating elements of the planetary gear sets of the gear mechanism 4 are formed integrally with the power transmission 7, 9 of the gear mechanism 4. In FIG. 1, the power transmission 7, 9 of the gear mechanism 4 is formed by a one-piece freewheel element carrier 9. The planet carrier PT of the planetary gear sets of the gear mechanism 4 is formed integrally with this power transmission 9.

[0033] The first freewheel element F1 and the second freewheel element F2 are shown in FIG. 1 as first and second claws F1, F2, respectively, on the one-piece freewheel element carrier 9. The first and second claws F1, F2 are arranged axially adjacent to each other with respect to the longitudinal axis LA of the drive shaft 7. Furthermore, in FIG. 1, the first and second claws F1, F2 are oriented radially outward, i.e., in the same direction, with respect to the longitudinal axis LA of the drive shaft 7. Furthermore, in FIG. 1, the first and second claws F1, F2 are arranged at a relatively small predetermined distance from the longitudinal axis LA of the drive shaft 7.

[0034] Figure 2 shows diagrammatically details of an electric drive 11 according to another embodiment. Elements of the drive 11 which are given the same reference numbers in Figure 2 are equivalent to elements of the drive 1 of Figure 1. These elements are not further detailed in the description of Figure 2.

[0035] The drive 11 of FIG. 2 differs from the drive 1 of FIG. 1 in that in this case the internal gear HR of the planetary gear set of the gear mechanism 4 can be coupled to the drive shaft 7 by means of a second freewheel element F2, in particular via a one-piece freewheel element carrier 9. As with the drive 1 of FIG. 1, in FIG. 2 the drive devices 7, 9 of the gear mechanism 4 are likewise formed by a one-piece freewheel element carrier 9. In contrast to FIG. 1, in the drive 11 of FIG. 2 instead of the planet carrier PT of the planetary gear set of the gear mechanism 4 the sun gear SR and the one-piece freewheel element carrier 9 are formed in one piece.

[0036] In FIG. 2, the first freewheel element F1 and the second freewheel element F2 are likewise designated as first and second claws F1, F2, respectively. The first and second claws F1, F2 are arranged radially adjacent to one another, at least partially, with respect to the longitudinal axis LA of the drive shaft 7. Furthermore, in FIG. 2, with respect to the longitudinal axis LA of the drive shaft 7, the first claw F1 is oriented radially inward, whereas the second claw F2 is oriented radially outward. This allows a reduction in the axial installation space of the drive device 11 compared to the embodiment of FIG. 1. Furthermore, in FIG. 2, the first and second claws F1, F2 are arranged at a greater predetermined distance from the longitudinal axis LA of the drive shaft 7 compared to FIG. 1.

[0037] Figure 3a shows diagrammatically details of an electric drive 21 according to another embodiment. Elements of the drive 21 which are given the same reference numbers in Figure 3 are equivalent to elements of the drive 1 of Figure 1 and the drive 11 of Figure 2. These elements will not be detailed further in the description of Figure 3.

[0038] In the drive 21 of Fig. 3a, the internal gear HR of the planetary gear set of the gear mechanism 4 can still be coupled to the drive shaft 7 by means of the second freewheel element F2, i.e. via a one-piece freewheel element carrier 9. In contrast to the drive 1 of Fig. 1 and the drive 11 of Fig. 2, however, in Fig. 3 the drive transmission 7, 9 of the gear mechanism 4 is formed by the drive shaft 7. In the drive 21 of Fig. 3 the sun gear SR of the planetary gear set of the gear mechanism 4 and the drive shaft 7 are thus formed in one piece.

[0039] In Fig. 3a, the first freewheel element F1 and the second freewheel element F2 are likewise designated as first and second pawls F1, F2, respectively. The first and second pawls F1, F2 are at least partially axially adjacent and radially inwardly oriented, i.e. in the same direction, relative to the longitudinal axis LA of the drive shaft 7. Furthermore, in Fig. 3, the first and second pawls F1, F2 are arranged at a greater predefined distance from the longitudinal axis LA of the drive shaft 7, as compared to Figs. 1 and 2. This allows the pawls F1, F2 to absorb a greater torque, as compared to the drives 1, 11.

[0040] FIG. 3b shows a schematic development of the drive device 21 according to FIG. 3a. In this case, the drive shaft 7' of the drive device 21 extends radially outward relative to the longitudinal axis LA. This embodiment offers the advantage that a further drive wheel 8', which transmits the drive force from the drive device 21 to the drive axle of the bicycle, can be mounted on the drive shaft 7' at a reduced distance from the drive shaft 7'. Furthermore, a sealing element 10a is arranged between the radially outwardly extending drive shaft 7' and the housing 10 of the drive device 21. Using the sealing element 10a, the housing 10 of the drive device 21 can be sealed against the ingress of dirt and / or moisture.

[0041] Figure 4 shows diagrammatically details of an electric drive 31 according to another embodiment. Elements of the drive 31 which are given the same reference numbers in Figure 4 are equivalent to elements of the drive 1 in Figure 1, the drive 11 in Figure 2 and the drive 21 in Figures 3a and 3b. These elements are not further detailed in the description of Figure 4.

[0042] In the drive 31 of FIG. 4, similarly to FIG. 1, the only partially depicted rotating element 12 of the planetary gear set of the gear mechanism 4 can be connected to the drive shaft 7 by means of the second freewheel element F2, in particular via a one-piece freewheel element carrier 9. In contrast to the drives 1, 11 and 21 of FIGS. 1, 2 and 3a, however, the power transmission device 7, 9 of the gear mechanism 4 is formed in FIG. 4 by both the drive shaft 7 and the one-piece freewheel element carrier 9. In FIG. 4, the sun gear SR of the planetary gear set of the gear mechanism 4 is formed in one piece with this power transmission device 7, 9. Thus, in the drive 31 of FIG. 4, the sun gear SR of the planetary gear set of the gear mechanism 4, the drive shaft 7 and the one-piece freewheel element carrier 9 are formed in one piece. This allows the drive 31 to be particularly simple to design, using fewer components than the designs of the drives 1, 11 and 21.

[0043] Furthermore, in the drive device 31 of FIG. 4, the drive wheel 8 is mounted on the housing 10 of the drive device 31. This allows the one-piece freewheel element carrier 9 to be arranged radially inside the ball bearing KL1 of the drive wheel 8 with respect to the longitudinal axis LA of the drive shaft 7. The freewheel element carrier 9 and the ball bearing KL1 can thus be arranged radially stacked. This allows the axial installation space with respect to the longitudinal axis LA of the drive shaft 7 to be reduced. [Explanation of symbols]

[0044] 1;11;21;31 Electric drive 3 Bottom bracket 4 Gear mechanism, planetary gear mechanism SR sun gear PR Planetary Gear PT Planet Carrier HR Internal Gear 5 Electric motor 6 pedal crankshaft 62 Pedal Crank 7;7' drive shaft 8;8' drive wheels 81 Traction devices, chains F1 First freewheel element, first pawl F2 Second freewheel element, second pawl 9 Freewheel Element Carrier 7;7';9 Power transmission device 10. Housing 10a Sealing elements 12 Rotational Elements L1, L2 bearings KL1 Ball Bearing LA Longitudinal axis of the drive shaft

Claims

1. An electric drive (1; 11; 21; 31) for a bicycle, comprising: a gear mechanism (4) arranged on the bottom bracket (3) of the bicycle and comprising at least one planetary gear set, the planetary gear set comprising at least three rotating elements (12; SR, PT, HR), the rotating elements (12; SR, PT, HR) being arranged rotatably relative to one another and designed to transmit torque; an electric motor (5) offset relative to said gear mechanism (4); a drive shaft (7; 7') mounted on at least the pedal crankshaft (6) of said bicycle; a drive wheel (8) arranged coaxially with the drive shaft (7; 7') for transmitting motor power from the electric motor (5) to the drive shaft (7; 7'); a first freewheel element (F1); a second freewheel element (F2), said first freewheel element (F1) and said second freewheel element (F2) are arranged together in a one-piece freewheel element carrier (9); the drive wheel (8) is connectable to the drive shaft (7; 7') by means of the first freewheel element (F1) via the one-piece freewheel element carrier (9), one of the rotating elements (12; SR, PT, HR) of the planetary gear set of the gear mechanism (4) can be connected to the drive shaft (7; 7') by means of the second freewheel element (F2) via the one-piece freewheel element carrier (9), an electric drive, wherein another of the rotating elements (12; SR, PT, HR) of the planetary gear set of the gear train (4) is formed integrally with the power transmission (7; 7'; 9) of the gear train (4).

2. 2. An electric drive (1; 11; 21; 31) according to claim 1, wherein the power transmission (7; 7'; 9) of the gear mechanism (4) is formed by the drive shaft (7; 7').

3. 2. An electric drive (1; 11; 21; 31) according to claim 1, wherein the power transmission (7; 7'; 9) of the gear mechanism (4) is formed by the one-piece freewheel element carrier (9).

4. 2. An electric drive (1; 11; 21; 31) according to claim 1, wherein the power transmission (7; 7'; 9) of the gear mechanism (4) is formed by the drive shaft (7; 7') and the one-piece freewheel element carrier (9).

5. 5. An electric drive device (1; 11; 21; 31) according to any one of claims 1 to 4, wherein the drive shaft (7; 7') of the bicycle is mechanically operatively connected to at least one pedal crank (62), and a power transmission path runs from the pedal crank (62) to the drive shaft (7; 7') via the gear mechanism (4).

6. 6. An electric drive (1; 11; 21; 31) according to claim 5, wherein the motor power from the electric motor (5) is transmitted to the drive shaft (7; 7') in an end region of the power transmission path.

7. An electric drive (1; 11; 21) according to any one of claims 1 to 4, wherein the drive wheels (8) are mounted on the drive shaft (7; 7').

8. An electric drive (31) according to any one of claims 1 to 4, wherein the drive wheels (8) are mounted on a housing (10) of the drive (31).

9. 5. The drive device (1; 21; 31) according to any one of claims 1 to 4, wherein the first freewheel element (F1) and the second freewheel element (F2) are arranged axially adjacent to each other, at least partially, within the one-piece freewheel element carrier (9) relative to the longitudinal axis (LA) of the drive shaft (7; 7').

10. 5. The drive device (11) according to claim 1, wherein the first freewheel element (F1) and the second freewheel element (F2) are arranged at least partially diametrically adjacent to one another within the one-piece freewheel element carrier (9) relative to the longitudinal axis (LA) of the drive shaft (7; 7').

11. 5. The drive device (1; 21; 31) according to any one of claims 1 to 4, wherein the first freewheel element (F1) and the second freewheel element (F2) are oriented in the same direction within the one-piece freewheel element carrier (9) relative to the longitudinal axis (LA) of the drive shaft (7; 7').

12. 5. The drive device (11) according to any one of claims 1 to 4, wherein the first freewheel element (F1) and the second freewheel element (F2) are oriented in opposite directions within the one-piece freewheel element carrier (9) relative to the longitudinal axis (LA) of the drive shaft (7; 7').

13. 5. The drive device (1; 11; 21; 31) according to any one of claims 1 to 4, wherein the first freewheel element (F1) and the second freewheel element (F2) are arranged inside the one-piece freewheel element carrier (9) at a predetermined distance from the longitudinal axis (LA) of the drive shaft (7; 7').

14. A bicycle comprising an electric drive (1; 11; 21; 31) according to any one of claims 1 to 4 and two pedal cranks (62) arranged at opposite ends of the pedal crankshaft (6), the pedal cranks (62) being mechanically operably connected to the drive shaft (7; 7') attached to the pedal crankshaft (6) for human-powered driving of the bicycle (2).

Images