Drive unit for an electric bicycle, and planetary gear assembly with a gear pressed into the planet carrier

Abstract

In particular, the invention relates to a drive unit (A) for an electric bicycle (1), comprising a driveshaft (AT), an output shaft (AW), at least one electric motor (E1, E2), and a transmission device comprising at least one planetary gear stage (PG) which has a sun gear (42), a planet carrier (51), and a ring gear (53) and via which the driveshaft (AT) and the output shaft (AW) are coupled together. The transmission device comprises a coupling shaft (K1) which is connected to the drive shaft (AT) via a transmission stage (GP1) and is rotationally fixed to the planet carrier (51). The coupling shaft (K1) supports a drive gear (41) of the transmission stage (GP1), and a tooth head (410) of the drive gear (41) is pressed into a bearing opening (510) of the planet carrier (51) in order to rotationally fix the coupling shaft to the planet carrier (51).

Description

[0001] Drive unit for an electric bicycle and planetary gear assembly with gear pressed into planet carrier

[0002] Description

[0003] The proposed solution concerns in particular a drive unit for an electric bicycle.

[0004] Drive units for electric bicycles, such as e-bikes or pedelecs, are known. These are attached to the frame of the electric bicycle via a drive housing. In addition to a rotatably mounted drive shaft for applying muscle-powered drive power to propel the electric bicycle, they also have an output shaft mounted coaxially to the drive shaft for transmitting the drive power to a wheel of the electric bicycle. To apply additional assist power, at least one electric motor and a transmission device with a planetary gear stage can be housed in the drive housing.

[0005] In variants with two electric motors, a gear ratio of the planetary gear stage can be adjusted using first and second electric motors, so that the gearing device coupling the drive shaft and the output shaft allows a driver of the electric bicycle to continuously adjust the gear ratio. In a drive unit known in this regard from WO 2019 / 175022 A1, for example, three shaft trains are provided to compactly accommodate the components of the gearing device, a first rotor shaft of the first electric motor and a second rotor shaft of the second electric motor, as well as the drive shaft and the output shaft, in a drive housing.

[0006] However, there is still a need for drive units that allow a compact arrangement of the components within the drive housing.

[0007] The proposed solution provides a remedy here. Specifically, a drive unit for an electric bicycle is proposed, in which the transmission device comprises a (first) coupling shaft carrying a gearwheel and is non-rotatably connected to a planetary carrier of a planetary gear stage of the transmission device. The gearwheel, which is, for example, non-rotatably fixed to the coupling shaft or formed thereon, has a plurality of teeth. At least one tooth tip of a tooth of the drive gearwheel is pressed into a bearing opening in the planetary carrier to ensure a non-rotatable connection between the coupling shaft and the planetary carrier.

[0008] The proposed solution accordingly envisages using a gear already provided for a gear stage of the transmission in addition to the rotationally fixed connection of the coupling shaft to the planet carrier. To transmit drive force from the gear to the planet carrier, no additional section on the coupling shaft or an additional element to be fixed to the coupling shaft is necessary. Instead, one or more tooth tips of the gear itself are used to create a press connection to the planet carrier and thus to transmit drive force to the planet carrier in the transmission. As a result, a planetary gear assembly comprising the planet carrier, the coupling shaft, and the gear requires comparatively little axial space.

[0009] In this context, for example, one embodiment variant may also provide for the at least one tooth tip to be frictionally and / or positively connected to the planet carrier. In this context, it is provided, for example, that the press connection simultaneously creates a positive connection through elastic deformation of the tooth tip and / or an inner wall of the bearing opening of the planet carrier.

[0010] The at least one tooth tip can have a shoulder in the area of ​​the press connection. At the shoulder, the tip circle diameter of the tooth tip is larger than an adjacent area of ​​the at least one tooth tip, for example by less than a tenth of a millimeter, in particular several hundredths of a millimeter. In the area of ​​the shoulder, the tooth tip is therefore specifically designed with a (larger) oversize for the press connection to be produced. In this context in particular, it can be advantageous for the tip surface on the shoulder to be ground, in particular overground, for the press connection. In this way, in an area with a locally larger tip circle diameter, the tip surface can be ground without any problem while maintaining the interference fit. The gear can in principle be part of a (first) gear stage of the transmission device via which the coupling shaft is connected to the drive shaft.

[0011] In one design variant, the coupling shaft is rotatably mounted on a sun gear shaft, which supports the sun gear of the planetary gear stage. The coupling shaft can be rotatably mounted on the sun gear shaft via a bearing, the inner ring of which is non-rotatably connected to the sun gear shaft, and the outer ring of which is non-rotatably connected to the coupling shaft. The coupling shaft and the sun gear shaft are thus located on a (second) shaft train of the transmission and are mounted coaxially to each other.

[0012] To axially preload the planetary gear stage, an axial preloading element can be provided within the transmission device. The coupling shaft comprises, for example, a radially inwardly projecting, annular circumferential web section relative to the bearing axis defined by the sun gear shaft, which is axially opposite the outer ring of the bearing, via which the coupling shaft is rotatably mounted on the sun gear shaft. The element axially preloading the planetary gear stage is then supported on this web section of the coupling shaft and the outer ring of the bearing. Axial preload of the planetary gear stage can thus be integrated comparatively compactly on the coupling shaft.

[0013] The element that axially preloads the planetary gear stage can, for example, comprise a wave spring washer. Such a wave spring washer rests, for example, on the web section of the coupling shaft on the one hand and the outer ring of the (third) bearing on the other.

[0014] In one embodiment, the web section on which the prestressing element for the planetary gear stage is supported is formed on a radially inner side of a region of the coupling shaft, on the radially outer side of which the at least one tooth head pressed into the bearing opening is provided, in particular formed.

[0015] The sun gear shaft, on which the coupling shaft is rotatably mounted, can be rotatably mounted via a first bearing at a first bearing point of the drive housing and via a second bearing at a second bearing point of the drive housing. In one embodiment, in such a case, for example, it is further provided that the transmission device comprises a further (preloading) element which is supported at the first bearing point on a part of the drive housing and axially preloads the sun gear shaft in the direction of the second bearing point, relative to a physical bearing axis defined by the sun gear shaft. In this case, a preload force applied by the (preloading) element preloading the planetary gear stage and acting in a second axial direction can be smaller than a preload force applied by the other element preloading the sun gear shaft and acting in an opposite axial direction.By providing additional first and second elements that preload in opposing directions, which preload the sun gear shaft on the one hand and the planetary gear stage on the other, a defined preload on the components of the transmission device arranged on a second shaft train can be achieved with comparatively few elements. The respective components of the transmission device on the second shaft train can thus be easily preloaded axially with a predetermined minimum load, thereby reducing play in the second shaft train. This significantly reduces acoustic problems during operation of the drive unit, particularly while simultaneously requiring minimal axial space for the transmission device.

[0016] Although the proposed solution is also advantageous for drive units with only one electric motor, one embodiment can provide a drive unit with first and second electric motors. A transmission ratio of the planetary gear stage can then be adjustable (in particular continuously) using the first and second electric motors, wherein a torque generated by the first electric motor can be transmitted at least partially to the output shaft. For example, in this context it can be provided that the first electric motor, with a first rotor shaft driven by it, is provided on a third shaft train. The sun gear shaft, in turn, is arranged on a second shaft train, in particular with the coupling shaft and the planetary gear stage. The drive shaft, the output shaft, and a second rotor shaft driven by the second electric motor are in turn mounted coaxially to one another on a first shaft train.

[0017] For example, the coupling shaft connected in a rotationally fixed manner to the planetary carrier forms a first coupling shaft for a first gear stage of the transmission device, while the ring gear of the planetary gear stage is connected in a rotationally fixed manner to a second coupling shaft which carries an output gear for a second gear stage, via which the ring gear is connected to the output shaft.

[0018] The proposed solution further relates to a planetary gear assembly for a planetary gear stage in a drive unit for an electric bicycle. The planetary gear assembly comprises a planetary carrier, on which several (at least two, three, or four) planetary gears are each rotatably mounted, and a coupling shaft that is rotationally connected to the planetary carrier. For the rotationally fixed connection of the coupling shaft to the planetary carrier, the planetary carrier has a bearing opening into which a drive gear of the coupling shaft is pressed with at least one tooth tip.

[0019] The planetary gear assembly proposed in particular for use as part of a planetary gear stage in a drive unit for an electric bicycle is particularly suitable for a drive unit of a proposed drive unit.

[0020] The proposed solution also concerns an electric bicycle with a variant of a proposed drive unit.

[0021] The attached figures illustrate possible embodiments of the proposed solution.

[0022] Here we show:

[0023] Figure 1 shows a sectioned view of a variant of a proposed drive unit with a view of a second shaft train on which, in particular, a planetary gear stage is provided;

[0024] Figure 2 shows a further sectional view of the drive unit of Figure 1, in particular with supplemented force curves;

[0025] Figure 3 shows in perspective single representation the planetary gear stage without

[0026] ring gear;

[0027] Figure 3A is a sectional view of the planetary gear stage of Figure 3;

[0028] Figure 4 shows schematically an electric bicycle in which the drive unit of the

[0029] Figures 1 and 2 are used with the planetary gear stage of Figures 3 and 3A.

[0030] Figure 4 illustrates an electric bicycle 1 with an electric motor drive unit A. The electric bicycle 1 has a frame 10, which here, for example, comprises a top tube, a down tube, and a seat tube, and to which the drive unit A is attached in the region of an intersection point of the seat tube and the down tube. Part of the drive unit A are control electronics SE and a sensor device 15, for example designed with a torque sensor and a position sensor, for sensorically detecting a torque introduced by muscle power at a drive shaft AT (in the form of a bottom bracket shaft) of the drive unit A. The sensor device 15 can alternatively or additionally comprise a speed sensor, via which the speed of the drive shaft AT can be detected.

[0031] An output element of the drive unit A, here in the form of a hollow output shaft AW mounted coaxially to the drive shaft AT, is connected to a rear wheel 12 of the electric bicycle 1 via a belt or chain 13 as a power transmission element in order to drive the electric bicycle 1. A wheel sensor 14 for determining a travel speed of the electric bicycle 1 is assigned to this rear wheel 12, for example. Of course, the wheel sensor 14 can instead be provided on a front wheel 11 of the electric bicycle 1.

[0032] The drive unit A is part of a drive system of the electric bicycle 1, which further comprises an operating part 2. The operating part 2 is fastened in Figure 4, for example, in the area of ​​a handlebar of the electric bicycle 1 and is connected to the control electronics SE of the drive unit A. A user input can be recorded via the operating part 2 and used to control the drive unit A. For example, the operating part 2 further comprises at least one display to inform a user of the electric bicycle 1 about

[0033] - the current operating status of the drive unit A, for example with regard to a set support level,

[0034] - a charge state of a battery unit 3 supplying the drive unit A with electrical energy, which contains at least one (rechargeable) battery, and / or

[0035] - a set gear which specifies the ratio with which a drive torque introduced by muscle power at the drive shaft AT is transmitted to the output element of the drive unit A.

[0036] Figure 1 shows details of the drive unit A with a view into the interior of a drive housing G of the drive unit A. The drive shaft AT extends through the drive housing G and is connected on each side to a pedal crank, via which a rider of the electric bicycle 1 can apply drive force using muscle power. An output shaft AW protrudes from the drive housing G only on one side and is then connected, for example, to an output element in the form of a chain wheel or a toothed belt pulley, in order to drive the rear wheel 12 of the electric bicycle 1.

[0037] The drive unit A further comprises a first electric motor E1, which drives a first rotor shaft. This first electric motor E1, together with a second electric motor E2, which drives a second rotor shaft RW, is housed in a first housing part G1 of the drive housing G. The first housing part G1 is connected to a second housing part G2, which, together with the first housing part G1, defines an interior of the drive housing G, in which, in addition to the electric motors E1 and E2, a transmission device is housed. The first and second electric motors E1 and E2 are connected in this case via a power control and form a continuously variable electric actuating gear in order to be able to continuously adjust a transmission ratio of a planetary gear stage PG of the transmission device.The planetary gear stage PG is part of a multi-stage superposition gear, via which the input shaft AT, the output shaft AW and the two rotor shafts of the first and second electric motors E1 and E2 are coupled to one another, whereby in the illustration in Figure 1 only the second rotor shaft RW of the second electric motor E2 is visible.

[0038] The input shaft AT, the output shaft AW, and the rotor shaft RW of the second electric motor E2 are arranged coaxially on a first shaft train, while the planetary gear stage PG—in this case with three shafts—is arranged on a second shaft train, for which a physical bearing axis S is defined by a sun gear shaft 4. The first rotor shaft of the first electric motor E1 is in turn arranged on a third shaft train within the drive housing G, which runs parallel to the first and second shaft trains.

[0039] For the kinematic coupling of the gear elements of the drive unit A arranged on the three shaft trains, four gear stages GP1, GP2, GP3 and GP4, each designed as spur gear stages, are provided.

[0040] The drive shaft AT on the first shaft train is connected via a first gear stage GP1 to a first coupling shaft K1 on the second shaft train. For this purpose, the first coupling shaft K1 carries a drive gear 41 that meshes with an intermediate gear ZR. This intermediate gear ZR is rotationally fixedly connected to the drive shaft AT, optionally coupled to a freewheel. The first coupling shaft K1 is in turn rotationally fixedly connected to a planet carrier 51 of the planetary gear stage PG and is rotatably mounted on the sun gear shaft 4 via a third bearing L3—here designed as a double-row angular contact ball bearing.

[0041] The output shaft AW on the first shaft train is in turn connected to a second coupling shaft K2 via a second gear stage GP2. This second coupling shaft K2 carries an output gear 6, which meshes with a gear on the output shaft AW for the second gear stage GP2. The first gear stage GP1 increases the speed of the input shaft AT to a higher absolute speed of the first coupling shaft K1, which is connected to the second coupling shaft K2 via the planetary gear stage PG. The speed of the second coupling shaft K2 is transmitted to a lower speed of the output shaft AW with the gear ratio of the second gear stage GP2.

[0042] The (second) rotor shaft RW of the second electric motor E2 on the first shaft train is connected to the sun gear shaft 4 (as the third coupling shaft) on the second shaft train via a third gear stage GP3. For this purpose, a gear on the rotor shaft side meshes with a gear 43 that is non-rotatably connected to the sun gear shaft 4. The sun gear shaft 4 carries a sun gear 42 of the planetary gear stage PG, which meshes with the planet gears 52 of the planetary gear stage PG.

[0043] A ring gear 53 of the planetary gear stage PG is in turn connected in a rotationally fixed manner to the output gear 6 and is connected to the first rotor shaft of the first electric motor E1 via an external toothing via a fourth gear stage GP4.

[0044] In the embodiment of a proposed drive unit A shown in Figure 1, the sun gear shaft 4 is rotatably mounted at both of its longitudinal ends on the housing G. A first (lower in Figure 1) shaft end of the sun gear shaft 4 is rotatably mounted at a first housing-side bearing point GS1 via a first bearing L1 on the first housing part G1. The second (upper in Figure 1) longitudinal end of the sun gear shaft 4 is in turn rotatably mounted at a second housing-side bearing point GS2 via a second bearing L2. The second bearing point GS2 is defined by the second housing part G2. Viewed along the bearing axis S, starting from the first bearing point GS1 in a first axial direction, there follows a shaft section of the sun gear shaft 4, to which the gear 43 of the third gear stage GP3 is fixed.This is followed in the first axial direction along the bearing axis S by the third bearing L3 for the rotatable support of the first coupling shaft K1, before the sun gear 42 and thus the planetary gear stage PG follow in the first axial direction. This is followed in the first axial direction by the output gear 6 of the fourth gear stage GP4 in front of the second bearing point GS2 on the housing side.

[0045] Viewed in the axial direction, a printed circuit board P for the electronic control of the electric motors E1 and E2 is provided in the interior of the drive housing G between the gear 43 of the third gear stage GP3 and the first bearing L1 for the sun gear shaft 4. In this case, this circuit board is located in the area of ​​a parting plane between the two housing parts G1 and G2 for easier assembly.

[0046] In the illustrated drive unit A, the individual components of the transmission device are arranged very compactly on the bearing axis S of the second shaft train, defined by the sun gear shaft 4. At the same time, a comparatively small number of preload elements in the form of three wave spring washers WF1, WF2, and WF3, each applying a preload force, ensure that all bearings for the rotatable mounting of the components on the second shaft train are preloaded with a minimum load. This significantly reduces the occurrence of disturbing noises during operation of the drive unit A.

[0047] For example, a first wave spring washer WF1 is provided at the first bearing point GS1, which is supported on the one hand on the first housing part G1 and on the other hand on an outer ring of the first bearing L1 which rotatably supports the sun gear shaft 4 and is also designed as a double-row angular contact ball bearing.

[0048] A second wave spring washer WF2 serves to axially preload the planetary gear stage PG. While the first wave spring washer WF1 axially preloads the sun gear shaft 4 in the direction of its second bearing point and thus in the first axial direction (upwards in Figure 1) along the bearing axis S, the second wave spring washer WF2 axially preloads the planetary gear stage PG relative to the sun gear shaft 4 in the direction of the first bearing point GS1 and thus in the opposite, second axial direction. For this purpose, the second wave spring washer WF2 is supported in this case on an outer ring of the third bearing L3, via which the first coupling shaft K1 is rotatably mounted on the sun gear shaft 4. In addition, the second wave spring washer WF2 is supported on a web 411 of the first coupling shaft K1, which runs annularly around the bearing axis S and projects radially inwards.Since the first coupling shaft K1 is non-rotatably connected to the planet carrier 51 of the planetary gear stage PG, this achieves an axial preload of the planetary gear stage PG. The preload force applied by the first wave spring washer WF1 and acting in the first axial direction is set greater than the preload force applied by the second wave spring washer WF2 and acting in the opposite second axial direction. The preload of the planetary gear stage PG by the second wave spring washer WF2 is thus compensated by the larger, opposing preload force on the sun gear shaft 4 (and thus also a sun gear assembly comprising the sun gear shaft 4 and the components of the transmission device connected thereto in a non-rotatably manner).

[0049] A third wave spring washer WF3 is provided between the second bearing L2 for supporting the sun gear shaft 4 at the second housing-side bearing point GS2 and a fourth bearing L4, via which the second coupling shaft K2 carrying the output gear 6 is rotatably mounted on a shaft section of the sun gear shaft 4. This third wave spring washer WF3 is supported on the inner ring of the second bearing L2 and on the inner ring of the fourth bearing L4. In this way, the fourth bearing L4 is axially preloaded in the second axial direction (downward in Figure 1) via the third wave spring washer WF3. The second wave spring washer WF2 has a load-relieving effect on the fourth bearing L4, via whose outer ring - corresponding to the force curve shown in Figure 2 in the area of ​​a circularly outlined "3" - a toothing force of the four planetary gears 52 must be diverted in the first axial direction during operation of the drive unit A.

[0050] The sectional view in Figure 2 further illustrates a force curve, marked with “D” in a square border, for the preload force introduced via the first wave spring washer WF1 and acting in the first axial direction along the bearing axis S. A force curve, illustrated with “C” in a square border in Figure 2, for the (lower) preload force applied by the second wave spring washer WF2 in the opposite, second axial direction to the planetary gear stage PG, in turn counteracts the preload force of the first wave spring washer WF1 in the sun gear shaft 4 and the toothing force of the four planet gears 52 during operation of the drive unit A. The preload force of the third wave spring washer WF3, for which a force curve is illustrated with a “B” in a square border in Figure 2, in turn acts in the second axial direction on the inner ring of the fourth bearing L4.

[0051] The planet carrier 51 is mounted on the ring gear 53 via a sixth bearing L6, here designed as a deep groove bearing. This sixth bearing L6 is responsible, in particular, for absorbing the toothing force of the drive gear 41, which acts in the first drive direction during operation of the drive unit A via the first gear stage GP1. The sixth bearing L6 is secured by an inner ring to a shoulder 511 of the planet carrier 51 that protrudes in the first axial direction.

[0052] The ring gear 53 is in turn supported on the drive housing G via the output gear 6 connected thereto in a rotationally fixed manner by a fifth bearing L5. This fifth bearing L5 is arranged at a bearing point of the second housing part G2, which is concentric with the second bearing point GS2 for the sun gear shaft 4 and is provided radially further outward on the second housing part G2 with respect to the bearing axis S.

[0053] In order to further reduce the axial installation space, in the illustrated embodiment for the rotationally fixed connection between the first coupling shaft K1 and the planet carrier 51, a part of a tooth head 410 of the drive gear 41 is pressed into a bearing opening 510 of a cylindrical extension of the planet carrier 51.

[0054] As can be seen particularly in the enlarged views of Figures 3 and 3A, the bearing opening 510 is provided centrally on the planet carrier 51, which has a plurality of bearing pins 54 for the rotatable mounting of the plurality (in this case four) planet gears 52. Tooth tips 411 of the drive gear 41 are pressed into the central bearing opening 510, so that elastic deformation on the tip surfaces of the tooth tips 410 and / or on the inner wall of the bearing opening 510 creates a positive and frictional connection between a) the drive gear 41 and thus the first coupling shaft K1 and b) the planet carrier 51. Thus, a part of the drive gear 43, via which the connection to the drive shaft AT is established at the first gear stage GP1, is used for the rotationally fixed connection to the planet carrier 51.

[0055] For precise adjustment of the press fit, the tooth tips 410 each have a shoulder 4110 with a grinding area in an area located in the press-in direction. Here, the tip diameter is a few hundredths of a millimeter larger to allow for grinding of the diameter in the press fit area.

[0056] 1 electric bike

[0057] 10 (bicycle) frames

[0058] 11 Front wheel

[0059] 12 rear wheel

[0060] 13 Belt / Chain

[0061] 14 Wheel sensor

[0062] 15 Sensor device

[0063] 2 Control panel

[0064] 3 Battery unit (energy storage)

[0065] 4 sun gear shaft

[0066] 41 Drive gear

[0067] 410 tooth head

[0068] 4100 heel / grinding area

[0069] 411 Bridge (section)

[0070] 42 Sun gear

[0071] 43 gear

[0072] 51 planet carrier

[0073] 510 warehouse opening

[0074] 511 paragraph

[0075] 52 Planetary gear

[0076] 53 ring gear

[0077] 54 bearing journals

[0078] 6 Output gear

[0079] A drive unit

[0080] AT drive shaft

[0081] AW output shaft

[0082] E1, E2 electric motor

[0083] G Drive housing

[0084] G1, G2 housing part

[0085] GP1 - GP4 gear stage

[0086] GS1, GS2 storage location

[0087] K1 First coupling shaft

[0088] K2 Second coupling shaft

[0089] L1 - L6 bearings

[0090] P Circuit board PG Planetary gear stage

[0091] RW rotor shaft

[0092] S bearing axis

[0093] SE control electronics

[0094] WF1, WF2, WF3 wave spring washer

[0095] ZR intermediate gear

Claims

Claims 1 . Drive unit for an electric bicycle (1), with a drive shaft (AT) for the muscle-powered application of a drive force for driving the electric bicycle (F), an output shaft (AW) for transmitting the drive force to a wheel (12) of the electric bicycle (1), at least one electric motor (E1, E2), a transmission device with at least one planetary gear stage (PG) having a sun gear (42), a planet carrier (51) and a ring gear (53), via which the drive shaft (AT) and the output shaft (AW) are coupled to one another, wherein the transmission device comprises a coupling shaft (K1) which carries a gear (41) which is connected in a rotationally fixed manner to the planet carrier (51), characterized in that at least one tooth tip (410) of the drive gear (41) is pressed into a bearing opening (510) of the planet carrier (51) for the rotationally fixed connection of the coupling shaft (K1) to the planet carrier (51).

2. Drive unit according to claim 1, characterized in that the at least one tooth head (410) is connected to the planet carrier (51) in a frictional and / or positive manner.

3. Drive unit according to claim 1 or 2, characterized in that the at least one tooth head (410) has a shoulder (4110) in the region of the press connection.

4. Drive unit according to claim 3, characterized in that at the shoulder (4110) the tip circle diameter of the tooth tip (410) is larger than an adjacent region of the at least one tooth tip (410).

5. Drive unit according to claim 3 or 4, characterized in that the head surface on the shoulder (4110) is ground, in particular ground over, for the press connection.

6. Drive unit according to one of the preceding claims, characterized in that the gear (41) is part of a gear stage (GP1) via which the coupling shaft (K1) is connected to the drive shaft (AT).

7. Drive unit according to one of the preceding claims, characterized in that the coupling shaft (K1) is rotatably mounted on a sun gear shaft (4) which carries the sun gear (42) of the planetary gear stage (PG).

8. Drive unit according to claim 7, characterized in that the coupling shaft (K1) is rotatably mounted on the sun gear shaft (4) via a bearing (L3), the inner ring of which is connected in a rotationally fixed manner to the sun gear shaft (4) and the outer ring of which is connected in a rotationally fixed manner to the coupling shaft (K1).

9. Drive unit according to claim 8, characterized in that the coupling shaft (K1) comprises a radially inwardly projecting, annularly encircling web section (411) axially opposite the outer ring, and an element (WF2) is provided which axially prestresses the planetary gear stage (PG) and is supported on the web section (411) of the coupling shaft (K1) and the outer ring of the bearing (L3).

10. Drive unit according to claim 9, characterized in that the element (WF2) axially prestressing the planetary gear stage (PG) comprises a wave spring washer (WF2).

11. Drive unit according to claim 9 or 10, characterized in that the web section (411) is formed on a radially inner side of a region of the coupling shaft (K1), on the radially outer side of which the at least one tooth head (411) pressed into the bearing opening (511) is provided, in particular formed.

12. Drive unit according to one of claims 7 to 11, characterized in that the sun gear shaft (4) forms a physical bearing axis (S) for a second shaft train of the drive unit (A), on which the planetary gear stage (PG) is arranged, and the sun gear shaft (4) is rotatably mounted on the one hand via a first bearing (L1) at a first bearing point (GS1) of the drive housing (G) and via a second bearing (L2) at a second bearing point (GS2) of the drive housing (G).

13. Drive unit according to claims 9 and 12, characterized in that the transmission device comprises a further element (WF1) which is supported at the first bearing point (GS1) on a part (G1) of the drive housing (G) and the Sun gear shaft (4) is axially preloaded in the direction of the second bearing point (GS2), relative to the bearing axis (S).

14. Drive unit according to claim 13, characterized in that a preload force applied by the element (WF2) preloading the planetary gear stage and acting in a second axial direction is smaller than a preload force applied by the other element (WF1) preloading the sun gear shaft (4) and acting in an opposite first axial direction.

15. Drive unit according to one of the preceding claims, characterized in that the drive unit (A) comprises a first electric motor (E1) and a second electric motor (E2) and a transmission ratio of the planetary gear stage (PG) can be adjusted by means of the first and second electric motors (E1, E2), wherein a torque generated by the first electric motor (E1) can be transmitted at least partially to the output shaft (AW).

16. Drive unit according to one of the preceding claims, characterized in that the coupling shaft (K1) connected in a rotationally fixed manner to the planet carrier (51) is a first coupling shaft for a first gear stage (GP1) of the transmission device and the ring gear (53) is connected in a rotationally fixed manner to a second coupling shaft (K2) which carries an output gear (6) for a second gear stage (GP2), via which the ring gear (53) is connected to the output shaft (AW).

17. Electric bicycle with a drive unit (A) according to one of the preceding claims.

18. Planetary gear assembly for a planetary gear stage (PG) in a drive unit (A) for an electric bicycle (1), with a planet carrier (51) on which a plurality of planet gears (52) are each rotatably mounted and a coupling shaft (K1) which is connected in a rotationally fixed manner to the planet carrier (51), characterized in that the planet carrier (51) comprises a bearing opening (510) and the coupling shaft (K1) carries a drive gear (41), wherein at least one tooth head (410) of the drive gear (41) is pressed into the bearing opening (510) of the planet carrier (51) for the rotationally fixed connection of the coupling shaft (K1) to the planet carrier (51).

Images