Planetary gear assembly with press-fitted gears for electric bicycle drive unit and planetary carrier

Abstract

The proposed solution relates in particular to a drive unit (A) for an electric bicycle (1), comprising a drive shaft (AT), an output shaft (AW), at least one electric motor (E1, E2), and a gear mechanism having at least one planetary gear stage (PG) including a sun gear (42), a planetary carrier (51), and a ring gear (53), through which the drive shaft (AT) and the output shaft (AW) are coupled to each other. The gear mechanism comprises a connecting shaft (K1) connected to the drive shaft (AT) via a gear stage (GP1) and non-rotatably connected to the planetary carrier (51). The connecting shaft (K1) carries the drive gear (41) of the gear stage (GP1), and the teeth (410) of the drive gear (41) are press-fitted into the bearing opening (510) of the planetary carrier (51) for non-rotatable connection with the planetary carrier (51).

Description

Technical Field

[0001] The proposed solution relates in particular to a drive unit for an electric bicycle.

Background Art

[0002] For example, a drive unit for an electric bicycle such as a so-called e-bike or a pedelec, which is fixed to the frame of the electric bicycle via a drive housing and is rotatably attached to a drive shaft for imparting a driving force for driving the electric bicycle by human power, is known to have an output shaft attached coaxially with the drive shaft for transmitting the driving force to the wheel. In order to apply an additional assist force, at least one electric motor and a gear mechanism having a planetary gear stage can be housed in the drive housing.

[0003] In a variant with two electric motors, the gear ratio of the planetary gear stage can be adjusted by the first and second electric motors, so that the gear ratio for the driver of the electric bicycle can be continuously adjusted using the gear mechanism connecting the drive shaft and the output shaft. In this regard, for example, in the drive unit known from Patent Document 1, three shaft rows are provided in order to compactly house the components of the gear mechanism, the first rotor shaft of the first electric motor and the second rotor shaft of the second electric motor, as well as the drive shaft and the output shaft, in the drive housing.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, there is still a need for a drive unit that enables a compact arrangement of components within the drive housing. [Means for solving the problem]

[0006] The proposed solution provides improvement measures here.

[0007] In particular, a drive unit for an electric bicycle is proposed, wherein the gear mechanism comprises a (first) connecting shaft that supports a gear and is non-rotatably connected to the planetary carrier of the planetary gear stage of the gear mechanism. For example, the gear, which is non-rotatably fixed to the connecting shaft or formed on the connecting shaft, has multiple teeth. To non-rotatably connect the connecting shaft to the planetary carrier, at least one tooth tip of the drive gear is press-fitted into the bearing opening of the planetary carrier.

[0008] Therefore, the proposed solution offers to use a gear already intended for the gear stages of a gear mechanism for an additional non-rotatable connection between the connecting shaft and the planetary carrier. Thus, no additional parts on the connecting shaft or additional elements fixed to the connecting shaft are required to transmit driving force from the gear to the planetary carrier. Instead, one or more teeth of the gear itself are used to establish a press-fit connection to the planetary carrier, thereby enabling the transmission of driving force to the planetary carrier within the gear mechanism. As a result, the planetary gear assembly, comprising the planetary carrier, connecting shaft, and gear, requires only a relatively small axial installation space.

[0009] In this context, for example, in one embodiment, at least one tooth tip may be configured to connect to the planetary carrier by friction and / or shape fitting, in which, for example, press-fitting is defined to simultaneously produce shape fitting by elastic deformation of the tooth tip and / or the inner wall of the bearing opening of the planetary carrier.

[0010] At least one tooth tip may have a stepped portion in the region of the press-fit connection. In the stepped portion, the tip diameter of the tooth tip is larger than that of the adjacent region of the at least one tooth tip, for example, less than a tenth of a millimeter, and especially a few hundredths of a millimeter. Thus, in the region of the stepped portion, the tooth tip is specifically designed to have a larger interference fit for the press-fit to be created. Particularly in this context, it may be advantageous for the tooth tip surface in the stepped portion to be ground, especially overground, for the press-fit. This means that grinding of the tooth tip surface in a region with a locally larger tip diameter can be easily achieved while maintaining interference fit.

[0011] A gear can essentially be part of the (first) gear stage of a gear mechanism in which a connecting shaft is connected to a drive shaft.

[0012] In one embodiment, the connecting shaft is rotatably mounted on the sun gear shaft, which supports the sun gear of the planetary gear stage. The connecting shaft can be rotatably mounted on the sun gear shaft via a bearing in which the inner ring is non-rotatably connected to the sun gear shaft and the outer ring is non-rotatably connected to the connecting shaft. Thus, the connecting shaft and the sun gear shaft are located in the (second) shaft row of the gear mechanism and are mounted coaxially with each other.

[0013] An axial preloading element may be provided within the gear mechanism to provide axial preload to the planetary gear stage. The connecting shaft may have, for example, an annular circumferential web that projects radially inward with respect to the bearing axis defined by the sun gear shaft, and which is axially opposed to the outer ring of the bearing on which the connecting shaft is rotatably mounted to the sun gear shaft. In this case, the element that provides axial preload to the planetary gear stage is supported by the web of the connecting shaft and the outer ring of the bearing. In this way, the axial preload of the planetary gear stage can be incorporated into the connecting shaft in a relatively compact manner.

[0014] Elements that provide axial preload to the planetary gear stage may include, for example, corrugated spring washers. Such corrugated spring washers are supported, for example, on the web of the connecting shaft on one side and on the outer ring of the (third) bearing on the other side.

[0015] In one embodiment, the web portion supporting the preload element for the planetary gear stage is formed radially inward of the region of the connecting shaft, and is specifically formed radially outward of that region, having at least one tooth tip that is press-fitted into a bearing opening.

[0016] The sun gear shaft, on which the connecting shaft is rotatably mounted, can be rotatably mounted via a first bearing at a first bearing position in the drive housing and a second bearing at a second bearing position in the drive housing. In one embodiment, for example, the gear mechanism is further specified to include a further (preload) element, which is supported in part of the drive housing at the first bearing position and preloads the sun gear shaft axially in the direction of the second bearing position with respect to the physical bearing axis defined by the sun gear shaft.

[0017] In this case, the preload applied by the element preloading the planetary gear stage and acting in the second axial direction may be less than the preload applied by the other element preloading the sun gear shaft and acting in the opposite axial direction. By providing additional first and second elements that apply preload in opposite directions, and using them to apply preload to the sun gear shaft on one hand and the planetary gear stage on the other, it is possible to achieve a predetermined preload for the components of the gear mechanism arranged in the second axle row with relatively few elements. Thus, each component of the gear mechanism on the second axle row can be easily preloaded axially with a specified minimum weight, and play in the second axle row can be reduced. This significantly reduces acoustic problems in the operation of the drive unit, especially when the gear mechanism requires little axial installation space.

[0018] The proposed solution is also advantageous for a drive unit having only one electric motor, but in one embodiment, a drive unit having first and second electric motors may be provided. In that case, the gear ratio of the planetary gear stage can be adjusted in particular continuously with the help of the first and second electric motors, thereby enabling the torque generated by the first electric motor to be transmitted at least partially to the output shaft. For example, in this context, the first electric motor having a first rotor shaft driven by it may be configured to be located in a third shaft row. The sun gear shaft is also located in a second shaft row, in particular together with the coupling shaft and the planetary gear stage. The drive shaft, output shaft, and second rotor shaft driven by the second electric motor are also mounted coaxially with each other in the first shaft row.

[0019] For example, a connecting shaft that is non-rotatably connected to a planetary carrier forms a first connecting shaft for a first gear stage of the gear mechanism, while the ring gear of the planetary gear stage is non-rotatably connected to a second connecting shaft that carries an output gear for a second gear stage, and the ring gear is connected to the output shaft via this second gear stage.

[0020] The proposed solution also 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 having a plurality of planetary gears, each rotatably mounted, at least two, three, or four, and a connecting shaft non-rotatably connected to the planetary carrier. To non-rotatably connect the connecting shaft to the planetary carrier, the planetary carrier has bearing openings into which the drive gear of the connecting shaft is press-fitted with at least one tooth tip.

[0021] The planetary gear assembly proposed for use as part of a planetary gear stage in a drive unit for electric bicycles is particularly suitable for the drive unit of the proposed drive unit.

[0022] The proposed solution also relates to electric bicycles with the proposed design modifications of the drive unit. [Brief explanation of the drawing]

[0023] The attached drawings show examples of possible embodiments of the proposed solution.

[0024] [Figure 1] It is a cross-sectional view showing in part an embodiment of the drive unit according to the proposal, paying particular attention to a second row of shafts provided with a planetary gear stage. [Figure 2] It is a further cross-sectional view of the drive unit of FIG. 1, particularly showing an additional force transmission path. [Figure 3] It is a single-piece perspective view showing the planetary gear stage excluding the ring gear. [Figure 3A] It is a cross-sectional view of the planetary gear stage of FIG. 3. [Figure 4] It is a diagram schematically showing an electric bicycle in which the drive units of FIGS. 1 and 2 are used together with the planetary gear stages of FIGS. 3 and 3A.

Mode for Carrying Out the Invention

[0025] FIG. 4 shows an electric bicycle 1 equipped with an electric motor type drive unit A. The electric bicycle 1 has a frame 10, which in this example includes a top tube, a down tube, and a seat tube, and the drive unit A is attached in the region of the intersection of the seat tube and the down tube. As part of the drive unit A, there is control electronics SE and a sensor device 15 designed using, for example, a torque sensor and a position sensor, which is for sensor-based detection of the torque applied by an input to the drive shaft AT (in the form of a bottom bracket shaft) of the drive unit A. The sensor device 15 may alternatively or additionally include a speed sensor for detecting the speed of the drive shaft AT.

[0026] The output element of the drive unit A (in this case, a hollow output shaft AW mounted coaxially with the drive shaft AT) is connected to the rear wheel 12 of the electric bicycle 1 via a belt or chain 13 as a power transmission element, enabling the electric bicycle 1 to be driven. For example, a wheel sensor 14 for determining the speed of the electric bicycle 1 is assigned to this rear wheel 12. Of course, the wheel sensor 14 could instead be installed on the front wheel 11 of the electric bicycle 1.

[0027] The drive unit A is part of the drive system of the electric bicycle 1, and this system also includes a control unit 2. As shown in Figure 4, the control unit 2 is mounted, for example, in the area of ​​the handlebars of the electric bicycle 1 and is connected to the control electronic equipment SE of the drive unit A. User input is recorded via the control unit 2 and can be used to control the drive unit A. For example, the control unit 2 also includes at least one display for informing the user of the electric bicycle 1 of the following information:

[0028] For example, the current operating state of the drive unit A with respect to the set assist level, the charge state of the battery unit 3 which includes at least one (rechargeable) battery and supplies electrical energy to the drive unit A, and / or the set gear which specifies the gear ratio at which the drive torque applied by human power to the drive shaft AT is transmitted to the output element of the drive unit A.

[0029] Figure 1 shows details of the drive unit A, focusing on the inside of the drive housing G. The drive shaft AT penetrates the drive housing G and is connected to the pedal crank on each side, through which the driver of the electric bicycle 1 can apply driving force using human power. The output shaft AW protrudes from the drive housing G on only one side and is connected to an output element in the form of, for example, a chain wheel or a toothed belt pulley to drive the rear wheel 12 of the electric bicycle 1.

[0030] The drive unit A also has a first electric motor E1 that drives the first rotor shaft. This first electric motor E1, together with a second electric motor E2 that drives the second rotor shaft RW, is housed in a first housing portion G1 of the drive housing G. The first housing portion G1 is connected to the second housing portion G2, which together with the first housing portion G1 defines the internal space of the drive housing G, where the gear mechanism is housed in addition to the electric motors E1 and E2. The first and second electric motors E1 and E2 are connected via a power control unit to form a continuously variable electric transmission, allowing for continuous adjustment of the gear ratio of the planetary gear stage PG of the gear mechanism. The planetary gear stage PG is part of a multi-stage superposition gear through which the drive shaft AT, output shaft AW, and the two rotor shafts of the first and second electric motors E1 and E2 are coupled to each other, although only the second rotor shaft RW of the second electric motor E2 is visible in the illustration in Figure 1.

[0031] The drive shaft AT, the output shaft AW, and the rotor shaft RW of the second electric motor E2 are arranged coaxially with the first shaft row, while the planetary gear stage PG, which in this case has three shafts, is arranged with its physical bearing axis S defined by the sun gear shaft 4. The first rotor shaft of the first electric motor E1 is also arranged with a third shaft row within the drive housing G, which extends parallel to the first and second shaft rows.

[0032] To kinematically connect the gear elements of drive unit A, which is arranged in three shaft rows, four gear stages GP1, GP2, GP3, and GP4 are provided, each designed as a spur gear stage.

[0033] The drive shaft AT on the first axle train is connected to the first coupling shaft K1 on the second axle train via the first gear stage GP1. 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 non-rotatably connected to the drive shaft AT and coupled to a freewheel as needed. The first coupling shaft K1 is also non-rotatably connected to the planetary carrier 51 of the planetary gear stage PG, which is rotatably mounted to the sun gear shaft 4 via a third bearing L3 designed as a double-row angular contact ball bearing.

[0034] The output shaft AW on the first shaft train is also connected to the second coupling shaft K2 via the second gear stage GP2. This second coupling shaft K2 carries an output gear 6 that meshes with the gear of the output shaft AW for the second gear stage GP2. The first gear stage GP1 increases the speed of the drive shaft AT to the higher absolute speed of the first coupling shaft K1, and the first coupling shaft K1 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 the lower speed of the output shaft AW at the gear ratio of the second gear stage GP2.

[0035] The (second) rotor shaft RW of the second electric motor E2 on the first axle train is connected to the sun gear shaft 4 (as the third connecting shaft) on the second axle train via the third gear stage GP3. For this purpose, the gear on the rotor shaft meshes with a gear 43 that is non-rotatably connected to the sun gear shaft 4. The sun gear shaft 4 carries the sun gear 42 of the planetary gear stage PG, which meshes with the planetary gears 52 of the planetary gear stage PG.

[0036] The ring gear 53 of the planetary gear stage PG is also non-rotatably connected to the output gear 6 and, in its external teeth, connected to the first rotor shaft of the first electric motor E1 via the fourth gear stage GP4.

[0037] In the proposed embodiment of drive unit A shown in Figure 1, the sun gear shaft 4 is rotatably mounted to the housing G at both of its longitudinal ends. The first (lower in Figure 1) end of the sun gear shaft 4 is rotatably mounted to the first housing portion G1 via a first bearing L1 at the first housing-side bearing position GS1. The second longitudinal end (upper in Figure 1) of the sun gear shaft 4 is also rotatably mounted via a second bearing L2 at the second housing-side bearing position GS2. The second bearing position GS2 is defined by the second housing portion G2. Viewed along the bearing axis S, starting from the first bearing position GS1 and moving in the first axial direction, is the shaft section of the sun gear shaft 4 to which the gear 43 of the third gear stage GP3 is fixed. Following this, in the first axial direction along the bearing axis S, there is a third bearing L3 for rotatably mounting the first connecting shaft K1, followed by a sun gear 42, and thus the planetary gear stage PG continues in the first axial direction. Following this, in the first axial direction, there is the output gear 6 of the fourth gear stage GP4 in front of the second bearing position GS2 on the housing side.

[0038] Viewed axially, a printed circuit board P for electronically controlling electric motors E1 and E2 is located inside 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. To facilitate assembly, it is located in the region of the separation surface between the two housing sections G1 and G2.

[0039] In the illustrated drive unit A, the individual components of the gear mechanism are arranged very compactly on the bearing axis S of the second axle row, defined by the sun gear shaft 4. At the same time, a relatively small number of (preload) elements, in the form of three corrugated spring washers WF1, WF2, and WF3, each providing preload, ensure that all bearings for rotatably mounting the components on the second axle row are preloaded with minimal weight. This significantly reduces the generation of unpleasant noise during the operation of the drive unit A.

[0040] For example, a first wave spring washer WF1 is provided at the first bearing position GS1, which is supported on the one hand by the first housing portion G1 and on the other hand by the outer ring of the first bearing L1, which rotatably supports the sun gear shaft 4 and is configured here as a double-row angular contact ball bearing.

[0041] The second corrugated spring washer WF2 serves to axially preload the planetary gear stage PG. The first corrugated spring washer WF1 axially preloads the sun gear shaft 4 in the direction of its second bearing position, and therefore in the first axial direction (upward in Figure 1) along the bearing axis S, while the second corrugated spring washer WF2 axially preloads the planetary gear stage PG relative to the sun gear shaft 4 in the direction of the first bearing position GS1, and therefore in the opposite second axial direction. For this purpose, the second corrugated spring washer WF2 is supported on the outer ring of the third bearing L3, which rotatably mounts the first connecting shaft K1 to the sun gear shaft 4. Furthermore, the second corrugated spring washer WF2 is supported on the web portion 411 of the first connecting shaft K1, which protrudes radially inward and extends annularly around the bearing axis S. The first connecting shaft K1 is non-rotatably connected to the planetary carrier 51 of the planetary gear stage PG, thereby providing axial preload to the planetary gear stage PG.

[0042] The preload applied by the first corrugated spring washer WF1, acting in the first axial direction, is set higher than the preload applied by the second corrugated spring washer WF2, acting in the opposite second axial direction. Therefore, the preload on the planetary gear stage PG by the second corrugated spring washer WF2 is compensated by a larger and opposite preload acting on the sun gear shaft 4 (and consequently, the sun gear assembly, including the sun gear shaft 4 and the gear mechanism components non-rotatably connected thereto).

[0043] A third corrugated spring washer WF3 is provided between the second bearing L2, which supports the sun gear shaft 4 at the second housing-side bearing position GS2, and the fourth bearing L4, which rotatably supports the second connecting shaft K2 carrying the output gear 6 in the shaft section of the sun gear shaft 4. This third corrugated spring washer WF3 is supported by the inner ring of the second bearing L2 and the inner ring of the fourth bearing L4. In this way, the fourth bearing L4 is preloaded axially in the second axial direction (downward in Figure 1) via the third corrugated spring washer WF3. The second corrugated spring washer WF3 reduces the load on the fourth bearing L4, and the meshing force of the four planetary gears 52 must be released in the first axial direction during the operation of the drive unit A via the outer ring of the fourth bearing L4 (corresponding to the force transmission path "3" shown in Figure 2).

[0044] The cross-sectional view in Figure 2 also illustrates the force transmission path labeled "D" for a preload applied via the first corrugated spring washer WF1 and acting in the first axial direction along the bearing axis S. The force transmission path indicated by "C" in Figure 2 illustrates a lower preload applied by the second corrugated spring washer WF2 in the opposite second axial direction along the bearing axis S. This force counteracts the preload of the first corrugated spring washer WF1 on the sun gear shaft 4 and counteracts the meshing force of the four planetary gears 52 during the operation of the drive unit A. The preload of the third corrugated spring washer WF3 (indicated by the force transmission path "B" in Figure 2) also acts in the second axial direction on the inner ring of the fourth bearing L4.

[0045] The planetary carrier 51 is attached to the ring gear 53 via a sixth bearing L6, which in this case is designed as a deep groove ball bearing. This sixth bearing L6 must absorb the meshing force of the drive gear 41 acting in the first drive direction via the first gear step GP1 during the operation of the drive unit A. The inner ring of the sixth bearing L6 is fixed to a step 511 that protrudes in the first axial direction of the planetary carrier 51.

[0046] The ring gear 53 is also supported by a fifth bearing L5 on the drive housing G, by an output gear 6 that is non-rotatably connected to it. This fifth bearing L5 is located at a bearing position on the second housing portion G2, which is concentric with the second bearing position GS2 for the sun gear shaft 4, and is positioned radially outward on the second housing portion G2 with respect to the bearing axis S.

[0047] To further reduce the axial installation space, in the illustrated embodiment, a non-rotatable connection is provided between the first connecting shaft K1 and the planetary carrier 51 by press-fitting a portion of the tooth tips 410 of the drive gear 41 into the bearing opening 510 of the cylindrical extension of the planetary carrier 51.

[0048] As can be seen particularly in the enlarged views of Figures 3 and 3A, the bearing opening 510 is located in the center of the planetary carrier 51, which has multiple bearing journals 54 for rotatably mounting multiple (in this case, four) planetary gears 52. The tooth tips 410 of the drive gear 41 are press-fitted into the central bearing opening 510, and as a result, elastic deformation of the tooth tip surface of the tooth tips 410 and / or the inner wall of the bearing opening 510 creates a connection between (a) the drive gear 41 and thus the first connecting shaft K1, and (b) the planetary carrier 51 by form and friction. Thus, a portion of the drive gear 43, which is responsible for establishing the connection to the drive shaft AT in the first gear stage GP1, is used for a non-rotatable connection with the planetary carrier 51.

[0049] For precise adjustment of the press-fit connection, each tooth tip 410 has a stepped portion 4110 with a grinding area in the region facing the press-fit direction. Here, the tooth tip diameter is several hundredths of a millimeter larger to allow grinding of the diameter in the region of the press-fit connection. [Explanation of symbols]

[0050] 1. Electric bicycle 10 (bicycle) frame 11 Front Wheel 12 Rear wheels 13 Belts / Chains 14 Wheel Sensors 15 Sensor device 2 Control Unit 3. Battery Unit (Energy Storage) 4 Sun gear shaft 41 Drive gear 410 Tooth tip 4100 Step section / grinding area 411 Web (Department) 42 Sun Gear 43 Gears 51 Planetary Carrier 510 Bearing opening 511 Multilayered section 52 Planetary gears 53 Ring Gear 54 Bearing Journal 6 Output Gears A Drive Unit AT drive shaft AW output axis E1, E2 Electric Motors G drive housing G1, G2 Housing section GP1~GP4 gear stages GS1, GS2 bearing positions K1 First connecting shaft K2 Second connecting shaft L1~L6 Bearings P Printed Circuit Board PG Planetary Gear Stage RW rotor shaft S bearing axis SE Control Electronics WF1, WF2, WF3 wave spring washers ZR intermediate gear

Claims

1. A drive unit for an electric bicycle (1), A drive shaft (AT) for applying human power to drive the aforementioned electric bicycle (F), An output shaft (AW) for transmitting the aforementioned driving force to the wheels (12) of the electric bicycle (1), At least one electric motor (E1, E2) and A gear mechanism comprising at least one planetary gear stage (PG) including a sun gear (42), a planetary carrier (51), and a ring gear (53), which connects the drive shaft (AT) and the output shaft (AW) to each other, It has, The gear mechanism has a connecting shaft (K1) that supports a gear (41) that is non-rotatably connected to the planetary carrier (51), A drive unit characterized in that, in order to non-rotatably connect the connecting shaft (K1) to the planetary carrier (51), at least one tooth tip (410) of the drive gear (41) is press-fitted into the bearing opening (510) of the planetary carrier (51).

2. The drive unit according to claim 1, characterized in that at least one tooth tip (410) is connected to the planetary carrier (51) by at least one of friction and morphological fitting.

3. The drive unit according to claim 1 or 2, characterized in that at least one tooth tip (410) has a stepped portion (4110) in the region of press-fit connection.

4. The drive unit according to claim 3, characterized in that the tip diameter of the tooth tip (410) is larger in the stepped portion (4110) than in the adjacent region of at least one tooth tip (410).

5. The drive unit according to claim 3 or 4, characterized in that the tooth tip surface of the stepped portion (4110) for press-fitting is ground, particularly over-ground.

6. The drive unit according to any one of the preceding claims, characterized in that the gear (41) is part of a gear stage (GP1) that connects the connecting shaft (K1) to the drive shaft (AT).

7. The drive unit according to any one of the preceding claims, characterized in that the connecting shaft (K1) is rotatably attached to the sun gear shaft (4) that supports the sun gear (42) of the planetary gear stage (PG).

8. The drive unit according to claim 7, characterized in that the connecting shaft (K1) is rotatably mounted on the sun gear shaft (4) via a bearing (L3) having an inner ring that is not rotatably connected to the sun gear shaft (4) and an outer ring that is not rotatably connected to the connecting shaft (K1).

9. The connecting shaft (K1) has a web portion (411) that faces the outer ring in the axial direction and protrudes radially inward, extending in the circumferential direction. The drive unit according to claim 8, characterized in that an element (WF2) is provided that preloads the planetary gear stage (PG) in the axial direction, supported by the web portion (411) of the connecting shaft (K1) and the outer ring of the bearing (L3).

10. The drive unit according to claim 9, characterized in that the element (WF2) that preloads the planetary gear stage (PG) in the axial direction includes a wave spring washer (WF2).

11. The drive unit according to claim 9 or 10, characterized in that the web portion (411) is formed radially inward of the region of the connecting shaft (K1), and at least one tooth tip (411) press-fitted into the bearing opening (511) is provided on the radially outward side of the region, and is particularly formed.

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

13. The drive unit according to claims 9 and 12, characterized in that the gear mechanism is supported at the first bearing position (GS1) in a part (G1) of the drive housing (G), and has a further element (WF1) that preloads the sun gear shaft (4) axially in the direction of the second bearing position (GS2) with respect to the bearing axis (S).

14. The drive unit according to claim 13, characterized in that the preload applied by the element (WF2) that preloads the planetary gear stage and acting in the second axial direction is smaller than the preload applied by the further element (WF1) that preloads the sun gear shaft (4) and acting in the opposite first axial direction.

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

16. The connecting shaft (K1), which is non-rotatably connected to the planetary carrier (51), is the first connecting shaft for the first gear stage (GP1) of the gear mechanism. The drive unit according to any one of the preceding claims, characterized in that the ring gear (53) is non-rotatably connected to a second connecting shaft (K2) that carries an output gear (6) for a second gear stage (GP2) that connects the ring gear (53) to the output shaft (AW).

17. An electric bicycle equipped with a drive unit (A) as described in any one of the preceding claims.

18. A planetary gear assembly for a planetary gear stage (PG) in a drive unit (A) for an electric bicycle (1), comprising a planetary carrier (51) on which a plurality of planetary gears (52) are each rotatably mounted, and a connecting shaft (K1) that is non-rotatably connected to the planetary carrier (51), The planetary carrier (51) has a bearing opening (510), and the connecting shaft (K1) supports the drive gear (41). A planetary gear assembly characterized in that at least one tooth tip (410) of the drive gear (41) is press-fitted into the bearing opening (510) of the planetary carrier (51) in order to non-rotatably connect the connecting shaft (K1) to the planetary carrier (51).

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