Drive unit for electric bicycles, featuring an axially preloaded sun gear shaft and planetary gear stages.

Abstract

The proposed solution relates to a drive unit (A) of an electric bicycle (1), and comprises a gear mechanism located within a drive housing (G). The gear mechanism has at least one planetary gear stage (PG) including a sun gear (42), a planetary carrier (51), and a ring gear (53). The gear ratio of the planetary gear stage (PG) is adjustable by a first electric motor (E1) and a second electric motor (E2), and the drive shaft (AT) and the output shaft (AW) are interconnected via the planetary gear stage (PG). The sun gear shaft (4) is axially preloaded toward the second bearing position (GS2) by a first member (WF1) supported at the first bearing position (GS1) of the sun gear shaft (4), which is provided in a part (G1) of the drive housing (G). Furthermore, the second member (WF2) preloads the planetary gear stage (PG) axially toward the first bearing position (GS1) relative to the sun gear shaft (4).

Description

Technical Field

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

Background Art

[0002] The drive unit of an electric bicycle, so-called an E-bike or pedelec, is fixed to the frame of the electric bicycle via a drive housing, and includes a rotatable drive shaft for applying a driving force to drive the electric bicycle by muscular strength, and an output shaft arranged coaxially with the drive shaft for transmitting the driving force to the wheel of the electric bicycle. In order to apply an additional assist force, a first and a second electric motor and a gear mechanism having a planetary gear stage can be accommodated in the drive housing. The gear ratio of the planetary gear stage can be adjusted by the first and second electric motors, whereby the gear ratio for the rider of the electric bicycle can be continuously adjusted via the gear mechanism connecting the drive shaft and the output shaft. The drive unit disclosed in WO2019 / 175022A1, for example, includes three shaft rows, and compactly houses members of the gear mechanism, the first rotor shaft of the first electric motor, the second rotor shaft of the second electric motor, as well as the drive shaft and the output shaft, in the drive housing.

Summary of the Invention

Problems to be Solved by the Invention

[0003] However, there is still a need for a drive unit that can improve the assembly property while compactly arranging the members in the drive housing, and further can preload the members of the gear mechanism in the axial direction with space saving. Thereby, it becomes possible to eliminate, or at least reduce, abnormal noises caused by unnecessary play.

Means for Solving the Problems

[0004] The proposed solution provides a countermeasure here.

[0005] The proposed drive unit for electric bicycles includes at least the following: • Drive housing • A drive shaft rotatably mounted on the drive housing provides the driving force to propel the electric bicycle using muscle power. • Output shaft, which is coaxially positioned with the drive shaft on the first axle train, rotatably mounted in the drive housing, and transmits power to the wheels of the electric bicycle. • First electric motor and second electric motor A gear mechanism located within a drive housing and comprising at least one planetary gear stage including a sun gear, planetary carriers, and a ring gear, wherein the gear ratio of the planetary gear stage is adjustable by a first electric motor and a second electric motor, and the drive shaft and the output shaft are interconnected via the planetary gear stage.

[0006] The torque generated by the first electric motor can be transmitted, at least partially, to the output shaft. Furthermore, the gear mechanism includes a sun gear shaft that is rotationally fixed to the sun gear. This sun gear shaft forms the physical support axis of the second shaft row in which the planetary gear stage is arranged. The sun gear shaft is rotatably mounted on the one hand to a first bearing position in the drive housing via a first bearing, and on the other hand to a second bearing position in the drive housing via a second bearing. The gear mechanism further includes a (first) connecting shaft. This (first) connecting shaft is connected to the drive shaft via a (first) gear stage and rotationally fixed to the planetary carrier. The sun gear shaft is preloaded in the direction of the second bearing position, i.e., the first axial direction with respect to the support axis, by a first (preload) member supported at the first bearing position located in part of the drive housing. The planetary gear stage is preloaded by the second (preload) member in the direction of the first bearing position, i.e., the second axial direction opposite to the first axial direction, relative to the sun gear shaft.

[0007] By providing additional first and second members, and applying predetermined preloads to the sun gear shaft on one side and to the planetary gear stages relative to the sun gear shaft on the other, it becomes possible to apply the specified preload to the components of the gear mechanism arranged in the second shaft row with a relatively small number of components. Each component is preloaded axially with minimal load, thereby reducing play in the second shaft row. This significantly reduces acoustic problems during the operation of the drive unit.

[0008] The (1) connecting shaft is connected to the planetary carrier in a rotationally fixed state and is rotatably supported on the sun gear shaft via a third bearing. In one embodiment, a second member that preloads the planetary gear stage may be supported on this third bearing. For example, in this case, the second member that preloads the planetary gear stage may be supported on one side by the outer ring of the third bearing connected to the (1) connecting shaft, and on the other side by a part of the (1) connecting shaft.

[0009] In one embodiment, the second member is located axially opposite to the outer ring of the third bearing and is supported by the web portion of a connecting shaft that protrudes radially inward and extends to encircle the support axis. The preload of the planetary gear stage relative to the sun gear shaft can be adjusted by the second member via the connection between the third bearing and the sun gear shaft.

[0010] In one embodiment, to make the rotational fixed connection between the (first) connecting shaft and the planetary carrier more compact, the region of the connecting shaft forming the web is frictionally coupled and / or shape-engaged with the planetary carrier in the portion facing radially outward. This means that in one embodiment, the connecting shaft is equipped with a first gear stage output gear, and the teeth of at least one drive gear are press-fitted into the support opening of the planetary carrier, thereby connecting it to the planetary carrier in a rotational fixed state. Here, the teeth of at least one drive gear are used for the press-fit connection to the planetary carrier, thereby saving axial mounting space. The press-fit causes elastic deformation of the teeth and / or the support opening, thereby simultaneously obtaining a shape coupling between the teeth and the planetary carrier at the support opening.

[0011] A first (preload) member, provided to preload the sun gear shaft, sets the preload in the direction of the second bearing position on the housing side, and can be supported, for example, on the outer ring of the first bearing on one side and on the other side by the portion of the drive housing that defines the position of the first bearing.

[0012] As a general rule, the preload applied by the first member and acting in the first axial direction is greater than, or can be set to be greater than, the preload applied by the second (preload) member and acting in the second axial direction opposite to the first axial direction. Therefore, the preload on the sun gear shaft at the first bearing position compensates for the preload applied to the planetary gear stage in the opposite direction. This makes it easy to preload all bearings on the second shaft row with the minimum load and to minimize the number of preload members required for this purpose.

[0013] In principle, the first member and / or the second member can be made of an elastic material. In particular, both the first member and the second member can be equipped with corrugated spring washers. Corrugated spring washers allow for the setting of sufficiently high preload at a relatively low cost and are also easy to install.

[0014] In one embodiment, a second electric motor of the drive unit is mounted coaxially with the drive shaft and the output shaft, and thus drives a (second) rotor shaft located in the first axle train. The gear mechanism includes a gear that is rotationally fixed to the sun gear shaft and meshes with a gear provided on the (second) rotor shaft to form a further (third) gear stage. The gear of the further (third) gear stage, rotationally fixed to the sun gear shaft, may be located between the first and second members when viewed from the direction of the support axis. Therefore, the gear rotationally fixed to the sun gear shaft can be provided on the shaft portion of the sun gear shaft that extends between the first and third bearings. This makes it possible to arrange the components on the second axle train in a relatively space-saving manner.

[0015] A connecting shaft connected to the planetary carrier in a fixed rotational position may serve as the first connecting shaft for the first gear stage of the gear mechanism. The ring gear of the planetary gear stage is connected in a fixed rotational position to a second connecting shaft, which houses the output gear for the second gear stage, thereby connecting to the output shaft via the second gear stage. In one embodiment, this second connecting shaft is rotatably mounted to the sun gear shaft via a fourth bearing. Thus, the components of the gear mechanism are supported coaxially with each other around a support axis physically defined by the sun gear shaft and are arranged relatively compactly with respect to each other. Rotatable support on the sun gear shaft makes it relatively easy to apply axial preload to each component. In one embodiment, the output gear may be additionally supported by a fifth bearing provided in part of the housing. In one embodiment, a sixth bearing is provided for supporting the planetary carrier on a ring gear rotatably connected to the output gear.

[0016] In one modification, a third (preloading) member is additionally provided to apply axial preload to the components on the second shaft row. This third member is, for example, an elastic member and may in particular include a (third) corrugated spring washer. This third member preloads the fourth bearing, which rotatably supports the second connecting shaft relative to the sun gear shaft, in the direction of the first bearing position on the sun gear shaft (i.e., in the second axial direction). In this case, the third member may be supported on one side by the inner ring of the first bearing and on the other side by the inner ring of the fourth bearing. Thus, the fourth bearing is preloaded in the second axial direction (e.g., elastically) by the third member, thereby applying a specified preload.

[0017] In principle, the load on the fourth bearing can be reduced, at least partially, by a preload applied by the second member acting in the direction of the first bearing position. For example, the preload applied by the second member counteracts the axial meshing force generated in the planetary gears of the planetary gear stage, and as a result, this meshing force acting in the first axial direction needs to be absorbed by the fourth bearing. Therefore, a preload applied by the second member in the opposite direction, i.e., in the second axial direction, acts to reduce the load on the fourth bearing.

[0018] In one embodiment, when looking in the first axis direction from the first bearing position along the support axis, the following components of the gear mechanism are arranged in sequence. a. A gear rotationally fixed to the sun gear shaft b. The (first) connecting shaft rotationally fixed to the planetary carrier c. The planetary gear stage d. The output gear connected to the second connecting shaft

[0019] In principle, the first electric motor may drive the first rotor shaft, and the first rotor shaft of this first electric motor may be arranged in the third shaft row. This first rotor shaft is connected to the ring gear of the planetary gear stage arranged in the second shaft row via the fourth gear stage. In particular, the proposed solution enables the compact arrangement and axial preloading of the gear components on the second shaft row with relatively few members. This is particularly effective in a configuration where, in a variant of the drive unit, three shafts are arranged coaxially with each other on the second shaft row and four gear stages are provided.

[0020] In principle, at least one or all of the gear stages of the drive unit may be composed of spur gear stages. For the first bearing and the third bearing, it is suitable to use, for example, double-row angular ball bearings. However, this is not necessarily essential.

[0021] The proposed solution also relates to an electric bicycle having a variant of the proposed drive unit.

Brief Description of the Drawings

[0022] The accompanying drawings show possible variants of the proposed solution. [Figure 1] It is a partial cross-sectional view of one embodiment of the proposed drive unit, showing in particular the second shaft row provided with a planetary gear stage. [Figure 2] It is a further cross-sectional view of the drive unit of FIG. 1, particularly a view including an additional force curve. [Figure 3]It is a perspective view showing the planetary gear stage excluding the ring gear alone. [Figure 3A] It is a cross-sectional view of the planetary gear stage shown in FIG. 3. [Figure 4] It is a diagram schematically showing an electric bicycle including the drive unit shown in FIGS. 1 and 2 and the planetary gear stage shown in FIGS. 3 and 3A.

Mode for Carrying Out the Invention

[0023] FIG. 4 shows an electric bicycle 1 provided with an electric motor drive unit A. The electric bicycle 1 has a frame 10. In this example, the frame 10 includes a top tube, a down tube, and a seat tube. The drive unit A is attached in a region where the seat tube and the down tube intersect. The drive unit A includes control electronics SE and a sensor device 15. The sensor device 15 is constituted by, for example, a torque sensor and a position sensor, and detects the torque introduced by muscular force at the drive shaft (in the form of the bottom bracket shaft AT) of the drive unit A by the sensor. The sensor device 15 may alternatively or additionally include a speed sensor for detecting the rotational speed of the drive shaft AT.

[0024] Via a belt or chain 13 which is a transmission member, an output member of the drive unit A (here, a hollow output shaft AW attached coaxially with the drive shaft AT) is connected to the rear wheel 12 of the electric bicycle 1, whereby the electric bicycle 1 can be driven. As an example, a wheel sensor 14 for determining the traveling speed of the electric bicycle 1 is assigned to the rear wheel 12. Of course, the wheel sensor 14 may be provided on the front wheel 11 of the electric bicycle 1.

[0025] The drive unit A is part of the drive system of the electric bicycle 1 and also includes the control unit 2. In Figure 4, the control unit 2 is mounted, for example, in the handlebar area of ​​the electric bicycle 1 and connected to the control electronics SE of the drive unit A. User input is recorded via the control unit 2 and controls the drive unit A. For example, the control unit 2 further includes at least one display that shows the following information to the user of the electric bicycle 1. • Current operating status of drive unit A (set assist level, etc.) • The charge state of battery unit 3, which includes at least one rechargeable battery and supplies electrical energy to drive unit A. • Set gear (defines the gear ratio used when transmitting the drive torque generated in the drive shaft AT by muscle operation to the output member of the drive unit A)

[0026] Figure 1 shows the internal details of the drive housing G of the drive unit A. The drive shaft AT passes through the drive housing G, and both ends are connected to the pedal crank, allowing the rider of the electric bicycle 1 to apply driving force through muscle power via the pedal crank. The output shaft AW protrudes from only one side of the drive housing G and is connected to an output member, such as a chainwheel or a toothed belt pulley, to drive the rear wheel 12 of the electric bicycle 1.

[0027] The drive unit A is equipped with a first electric motor E1, which drives the first rotor shaft. The first electric motor E1, together with the second electric motor E2 which drives the second rotor shaft RW, is housed in the first housing section G1 of the drive housing G. The first housing section G1 is connected to the second housing section G2, and the internal space of the drive housing G is defined by both housing sections. In addition to the electric motors E1 and E2, a gear mechanism is housed in this internal space. The first electric motor E1 and the second electric motor E2 are connected via a power control unit, which together constitute an electric continuously variable 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, and the drive shaft AT, the output shaft AW, and both rotor shafts of the first electric motor E1 and the second electric motor E2 are interconnected via this superposition gear. Note that only the second rotor shaft RW of the second electric motor E2 is shown in Figure 1.

[0028] The drive shaft AT, output shaft AW, and rotor shaft RW of the second electric motor E2 are arranged coaxially on the first shaft row. Meanwhile, the planetary gear stage PG, which has three shafts, is arranged on the second shaft row, whose physical support axis S is defined by the sun gear shaft 4. The first rotor shaft of the first electric motor E1 is arranged within the drive housing G on a third shaft row that extends parallel to the first and second shaft rows.

[0029] To kinematically connect the gear members of drive unit A, which is arranged in three shaft rows, four gear stages GP1, GP2, GP3, and GP4 are provided, all of which consist of spur gear stages.

[0030] The drive shaft AT on the first axle train is connected to the first connecting shaft K1 on the second axle train via the first gear stage GP1. For this purpose, the first connecting shaft K1 is provided with a drive gear 41 that meshes with an intermediate gear ZR. This intermediate gear ZR is rotatably fixed to the drive shaft AT and is connected to a freewheel as needed. The first connecting shaft K1 is rotatably fixed to the planetary carrier 51 of the planetary gear stage PG and is rotatably mounted to the sun gear shaft 4 via a third bearing L3. The third bearing L3 here consists of a double-row angular contact ball bearing.

[0031] The output shaft AW of the first axle train is connected to the second connecting shaft K2 via the second gear stage GP2. The second connecting shaft K2 is equipped with an output gear 6 that meshes with the gear of the output shaft AW in 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 connecting shaft K1. The first connecting shaft K1 is connected to the second connecting shaft K2 via the planetary gear stage PG. The speed of the second connecting shaft K2 is converted and transmitted to the lower speed of the output shaft AW by the gear ratio of the second gear stage GP2.

[0032] The (second) rotor shaft RW of the second electric motor E2 of the first shaft train is connected to the sun gear shaft 4 (third connecting shaft) of the second shaft train via the third gear stage GP3. For this purpose, the gear on the rotor shaft meshes with a gear 43 that is fixed to the sun gear shaft 4 in a rotational position. The sun gear shaft 4 is provided with a sun gear 42 of the planetary gear stage PG, and this sun gear 42 meshes with a planetary gear 52 of the planetary gear stage PG.

[0033] The ring gear 53 of the planetary gear stage PG is connected to the output gear 6 in a rotationally fixed state, and its external teeth are connected to the first rotor shaft of the first electric motor E1 via the fourth gear stage GP4.

[0034] In the proposed embodiment of drive unit A shown in Figure 1, the sun gear shaft 4 is rotatably mounted at both of its longitudinal ends to the housing G. The first end of the sun gear shaft 4 (lower in Figure 1) is rotatably mounted via a first bearing L1 to a first housing-side bearing position GS1 on the first housing portion G1. The second longitudinal end of the sun gear shaft 4 (upper in Figure 1) is rotatably mounted via a second bearing L2 to a second housing-side bearing position GS2. The second bearing position GS2 is defined by the second housing portion G2. Viewed along the support axis S, the shaft portion of the sun gear shaft 4 continues from the first bearing position GS1 in the first axial direction, to which the gear 43 of the third gear stage GP3 is fixed. Viewed in the first axial direction along the support axis S, there is a third bearing L3 that rotatably supports the first connecting shaft K1, followed by the sun gear 42, and then the planetary gear stage PG. Further along the first axial direction, the output gear 6 of the fourth gear stage GP4 follows, and beyond that, the second bearing position GS2 on the housing side is located.

[0035] Viewed from the axial direction, the printed circuit board P for the electronic control of the electric motors E1 and E2 is located between the gear 43 of the third gear stage GP3 and the first bearing L1 of the sun gear shaft 4, and inside the drive housing G. To facilitate assembly, the printed circuit board P is located in the area of ​​the separation surface between the two housing sections G1 and G2.

[0036] In the illustrated drive unit A, the components of the gear mechanism are arranged very compactly on the support axis S of the second shaft row, defined by the sun gear shaft 4. At the same time, a relatively small number of (preloading) members, consisting of three corrugated spring washers WF1, WF2, and WF3, each applying preload, ensure that all bearings that rotatably support the components on the second shaft row are preloaded with minimal load. This significantly reduces the noise generated during the operation of drive unit A.

[0037] For example, a first corrugated spring washer WF1 is positioned at the first bearing position GS1. This first corrugated spring washer WF1 is supported on one end by the first housing portion G1 and on the other end by the outer ring of the first bearing L1, which rotatably supports the sun gear shaft 4. The first bearing L1 is similarly composed of a double-row angular contact ball bearing.

[0038] The second corrugated spring washer WF2 serves to preload the planetary gear stage PG in the axial direction. The first corrugated spring washer WF1 preloads the sun gear shaft 4 in the direction of its second bearing position, i.e., in the first axial direction (upward in Figure 1) along the support axis S. On the other hand, the second corrugated spring washer WF2 preloads the planetary gear stage PG relative to the sun gear shaft 4 in the direction of the first bearing position GS1, i.e., in the second axial direction opposite to the first axial direction. For this purpose, the second corrugated spring washer WF2 is supported on the outer ring of the third bearing L3, and the first connecting shaft K1 is rotatably attached to the sun gear shaft 4 via the third bearing L3. Furthermore, the second corrugated spring washer WF2 is supported on the web 411 of the first connecting shaft K1. This web 411 extends radially inward and has a ring-like shape that encircles the support axis S. The first connecting shaft K1 is connected to the planetary carrier 51 of the planetary gear stage PG in a rotationally fixed state, thereby preloading the planetary gear stage PG in the axial direction.

[0039] 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 direction, the second axial direction. The preload on the planetary gear stage PG by the second corrugated spring washer WF2 is compensated by a larger preload acting in the opposite direction on the sun gear shaft 4. This preload also acts on the sun gear assembly, which consists of the sun gear shaft 4 and the gear mechanism components connected to it in a rotationally fixed state.

[0040] The third corrugated spring washer WF3 is positioned between the second bearing L2, which supports the sun gear shaft 4 at bearing position GS2 on the second housing side, and the fourth bearing L4. The second connecting shaft K2, which has the output gear 6, is rotatably supported on the shaft portion of the sun gear shaft 4 via this fourth bearing L4. The 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 in the second axial direction (downward in Figure 1) via the third corrugated spring washer WF3. The second corrugated spring washer WF2 reduces the load on the fourth bearing L4. The outer ring of this fourth bearing L4 must release the meshing force of the four planetary gears 52 in the first axial direction during the operation of the drive unit A, corresponding to the force curve "3" shown in Figure 2.

[0041] The cross-sectional view in Figure 2 also shows a force curve "D" indicating the preload applied via the first corrugated spring washer WF1 and acting in the first axial direction along the support axis S. The force curve "C" shown in Figure 2 indicates a lower preload applied by the second corrugated spring washer WF2 in the second axial direction along the support axis S, opposite to the first axial direction. This force counteracts the preload from the first corrugated spring washer WF1 and the meshing force generated from the four planetary gears 52 during the operation of the drive unit A on the sun gear shaft 4. The preload from the third corrugated spring washer WF3 is represented by the force curve "B" in Figure 2 and acts in the second axial direction on the inner ring of the fourth bearing L4.

[0042] The planetary carrier 51 is attached to the ring gear 53 via a sixth bearing L6, which in this example is a grooved bearing. This sixth bearing L6 is particularly necessary to absorb the meshing force of the drive gear 41 acting in the first drive direction via the first gear stage GP1 during the operation of the drive unit A.

[0043] The sixth bearing L6 is fixed by an inner ring to the shoulder portion 511 of the planetary carrier 51, which protrudes in the first axial direction.

[0044] The ring gear 53 is supported by an output gear 6, which is connected in a fixed rotational state, via a fifth bearing L5 on the drive housing G. This fifth bearing L5 is located at the bearing position of the second housing portion G2. This bearing position is concentric with the second bearing position GS2 of the sun gear shaft 4 and is located radially outward from the second housing portion G2 with respect to the support axis S.

[0045] To further reduce the axial mounting space, in this embodiment, the first connecting shaft K1 and the planetary carrier 51 are connected in a rotationally fixed state by pushing a portion of the tooth tip 410 of the drive gear 41 into the support opening 510 of the cylindrical extension of the planetary carrier 51.

[0046] As particularly shown in the enlarged views of Figures 3 and 3A, the support opening 510 is located in the center of the planetary carrier 51. The planetary carrier 51 is provided with multiple bearing journals 54 for rotatably supporting a plurality (in this case, four) planetary gears 52. The teeth 410 of the drive gear 41 are press-fitted into the central support opening 510, and elastic deformation of the surface of the teeth 410 and / or the inner wall of the support opening 510 creates a shape engagement and friction coupling between (a) the drive gear 41 (and thus the first connecting shaft K1) and (b) the planetary carrier 51. A portion of the drive gear 43 is used for a rotational fixed connection to the planetary carrier 51, as a connection with the drive shaft AT is established through that portion in the first gear stage GP1.

[0047] To precisely adjust the press-fit connection, each tooth tip 410 is provided with a shoulder 4110, and the area of ​​this shoulder facing the press-fit direction is ground. The diameter of the tooth tip circle is formed to be several hundredths of a millimeter larger so that it can be adjusted by grinding at the press-fit connection. [Explanation of Symbols]

[0048] 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 Shoulder / grinding area 411 Web (Department) 42 Sangiya 43 gears 51 Planetary Carrier 510 Support opening 511 Shoulder 52 Planetary Gear 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 1st connection shaft K2 2nd connecting shaft L1-L6 Bearings P Printed Circuit Board PG Planetary Gear Stage RW rotor shaft S Support axis SE Control Electronics WF1, WF2, WF3 Corrugated Spring Washers ZR intermediate gear

Claims

1. A drive unit for an electric bicycle (1), Drive housing (G) and A drive shaft (AT) is rotatably mounted to the drive housing (G) and provides driving force generated by muscle power to drive the electric bicycle (F), An output shaft (AW) is arranged coaxially with the drive shaft (AT) on the first shaft row, rotatably mounted to the drive housing (G), and transmits driving force to the wheels (12) of the electric bicycle (1). First electric motor (E1), The second electric motor (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), disposed within the drive housing (G), wherein the gear ratio of the planetary gear stage (PG) is adjustable by the first electric motor (E1) and the second electric motor (E2), and the drive shaft (AT) and the output shaft (AW) are interconnected via the planetary gear stage (PG), Equipped with, At least a portion of the torque generated by the first electric motor (E1) can be transmitted to the output shaft (AW), The gear mechanism includes a sun gear shaft (4) which is rotatably fixed to the sun gear (42) and forms the physical support axis (S) of the second shaft row, the planetary gear stage (PG) is arranged on the second shaft row, and the sun gear shaft (4) is rotatably mounted on one side via a first bearing (L1) to the first bearing position (GS1) of the drive housing (G) and on the other side via a second bearing (L2) to the second bearing position (GS2) of the drive housing (G). The gear mechanism includes a connecting shaft (K1) which is connected to the drive shaft (AT) via a gear stage (GP1) and is fixed in rotation to the planetary carrier (51). A drive unit characterized in that the sun gear shaft (4) is preloaded axially toward the second bearing position (GS2) with respect to the support axis (S) by a first member (WF1) supported at the first bearing position (GS1) provided on a part (G1) of the drive housing (G), and the planetary gear stage (PG) is preloaded axially toward the first bearing position (GS1) with respect to the sun gear shaft (4) by a second member (WF2).

2. The drive unit according to claim 1, characterized in that the connecting shaft (K1), which is connected to the planetary carrier (51) in a rotationally fixed state, is rotatably mounted to the sun gear shaft (4) via a third bearing (L3).

3. The drive unit according to claim 2, characterized in that the second member (WF2) that preloads the planetary gear stage (PG) is supported by the third bearing (L3).

4. The drive unit according to claim 3, characterized in that the second member (WF2) that preloads the planetary gear stage (PG) is supported on one side by the outer ring of the third bearing (L3) connected to the connecting shaft (K1), and on the other side by a part (411) of the connecting shaft (K1).

5. The drive unit according to claim 4, characterized in that the second member (WF2) is supported by the web portion (411) of the connecting shaft (K1), the web portion is located on the opposite side in the axial direction from the outer ring, protrudes radially inward, and extends to surround the support axis (S) in an annular manner.

6. The drive unit according to claim 5, characterized in that the region of the connecting shaft (K1) that forms the web portion (411) is connected to the planetary carrier (51) by friction coupling and / or shape engagement in the portion (410) facing radially outward.

7. The drive unit according to claim 6, characterized in that the connecting shaft (K1) is equipped with a drive gear (41) of the gear stage (GP1), and the tooth tips (410) of the drive gear (41) are press-fitted into the bearing opening (510) of the planetary carrier (51), thereby connecting the drive gear (41) to the planetary carrier (51) in a rotationally fixed state.

8. The drive unit according to any one of claims 1 to 7, characterized in that the first member (WF1) is supported on one side by the outer ring of the first bearing (L1) and on the other side by the part (G1) of the drive housing (G).

9. A drive unit according to any one of claims 1 to 8, characterized in that the preload applied by the first member (WF1) and acting in the first axial direction is greater than the preload applied by the second member (WF2) and acting in the opposite direction, the second axial direction.

10. The drive unit according to any one of claims 1 to 9, characterized in that the first member (WF1) and / or the second member (WF2) are composed of elastic members including a corrugated spring washer in particular.

11. The second electric motor (E2) drives the rotor shaft (RW), which is mounted coaxially with the drive shaft (AT) and the output shaft (AW) and is located on the first shaft row. The drive unit according to any one of claims 1 to 10, characterized in that the gear mechanism comprises a gear (43) connected to the sun gear shaft (4) in a rotationally fixed state, and the gear (43) meshes with a gear provided on the rotor shaft (RW) to constitute a further gear stage (GP3).

12. The drive unit according to claim 11, characterized in that the gear (43) of the further gear stage (GP3), which is connected to the sun gear shaft (4) in a rotationally fixed state, is positioned between the first member (WF1) and the second member (WF2) when viewed along the support axis (S).

13. The connecting shaft (K1), which is connected to the planetary carrier (51) in a rotationally fixed state, is the first connecting shaft for the first gear stage (GP1) of the gear mechanism. A drive unit according to any one of claims 1 to 12, characterized in that the ring gear (53) is connected to the second connecting shaft (K2) in a rotationally fixed state, the second connecting shaft (K2) is equipped with an output gear (6) for the second gear stage (GP2), and the ring gear (53) is connected to the output shaft (AW) via the output gear (6).

14. The drive unit according to claim 13, characterized in that the second connecting shaft (K2) is rotatably mounted on the sun gear shaft (4) via a fourth bearing (L4).

15. The drive unit according to claim 14, characterized in that the drive unit (A) comprises a third member (WF3) that preloads the fourth bearing (L4) in the axial direction toward the first bearing position (GS1).

16. The drive unit according to claim 15, characterized in that the third member (WF3) is supported on one side by the inner ring of the first bearing (L1) and on the other side by the inner ring of the fourth bearing (L4).

17. A drive unit according to any one of claims 14 to 16, characterized in that the load on the fourth bearing (L4) is at least partially reduced by a preload applied by the second member (WF2) and acting in the direction of the first bearing position (GS1).

18. When viewed axially from the first bearing position (GS1) along the support axis (S), a. The gear (43) connected to the sun gear shaft (4) in a rotationally fixed state, b. The connecting shaft (K1) connected to the planetary carrier (51) in a rotationally fixed state, c. The planetary gear stage (PG), d. The output gear (6) connected to the second connecting shaft (K2) A drive unit according to any one of claims 11 or 12 and claims 13 to 17, characterized in that the components are arranged in order.

19. The first electric motor (E1) drives the first rotor shaft, A drive unit according to any one of claims 1 to 18, characterized in that the first rotor shaft of the first electric motor (E1) is arranged on a third shaft row and connected to the ring gear (53) on the second shaft row via a fourth gear stage (GP4).

20. An electric bicycle characterized by comprising a drive unit (A) as described in any one of claims 1 to 19.

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