Drive device for an electric bicycle and assembly for a drive device

Abstract

In at least one embodiment, the drive device (100) comprises a planetary gear (2) with a planet carrier (20), wherein the planet carrier is rotatably mounted about an axis of rotation (A) by means of a radial bearing (4) and an axial bearing (5).

Description

[0001] A drive device for an electric bicycle is described. Furthermore, an assembly for an electric bicycle drive device, a method for assembling an electric bicycle drive device, and an electric bicycle are described.

[0002] Bicycles offer a cost-effective, easy-to-use, and emission-free means of transportation. They have also become widespread as sports and fitness equipment, and certain types have proven particularly suitable for various sporting applications.

[0003] In recent years, enthusiasm for electric bicycles (especially so-called "pedelecs") has grown, despite their relatively high weight and price compared to other bicycles. A key requirement for electric bicycles is providing a reliable and supportive drive system.

[0004] One problem to be solved is to specify a drive device for an electric bicycle that contributes to efficient and low-wear operation of the electric bicycle. Further problems to be solved are to specify an assembly for such a drive device, a method for assembling such a drive device, and an electric bicycle equipped with such a drive device.

[0005] First, the drive system for an electric bicycle is specified.

[0006] In at least one embodiment, the drive device comprises a planetary gear with a planet carrier, wherein the planet carrier is rotatably mounted about an axis of rotation by means of a radial bearing and an axial bearing.

[0007] The present invention is based, among other things, on the understanding that axial forces, in addition to radial forces, can act on the planet carrier in the drive device. By combining a radial bearing and an axial bearing for supporting the planet carrier, all acting forces can be effectively absorbed, thereby minimizing wear on the drive device. This also results in efficient power transmission and low noise levels.

[0008] In the drive unit, the planet carrier is mounted so that it can rotate about an axis of rotation. This means, in particular, that the planet carrier is rotatable relative to a housing of the drive unit. Unless otherwise specified, directions parallel to the axis of rotation of the planet carrier are referred to here and in the following as "axial directions" or simply as "axial". Furthermore, unless otherwise indicated, the directional terms "radial" and "azimuthal" refer to this axis of rotation. The planet carrier, for example, is rotationally symmetrical with respect to its axis of rotation.

[0009] The planet carrier is rotatably mounted using a radial bearing and a thrust bearing. Both the radial and thrust bearings are rolling bearings. For example, only the radial bearing and the thrust bearing are used for the rotary mounting of the planet carrier. The radial bearing absorbs forces perpendicular to the axis of rotation of the planet carrier, i.e., radially acting forces, whereas the thrust bearing absorbs forces parallel to the axis of rotation, i.e., axially acting forces. The radial bearing is supported, for example, by the planet carrier. The radial bearing and the thrust bearing are arranged in axially opposite sections of the planet carrier; that is, the planet carrier is positioned axially between the radial bearing and the thrust bearing.

[0010] In addition to the planet carrier, the planetary gear set comprises a planet gear, which is rotatably mounted on the planet carrier, as well as a ring gear and a sun gear. The planet gear meshes with the sun gear and the ring gear. The ring gear may be fixed to the housing and therefore does not rotate during operation. The sun gear, for example, rotates around the same axis of rotation as the planet carrier. The axis of rotation of the planet gear runs parallel to, or substantially parallel to, the axis of rotation of the planet carrier. During operation, the axis of rotation of the planet gear rotates around the axis of rotation of the planet carrier. The planet carrier may be made of metal. The planet gear may be partially made of plastic.

[0011] For example, the planet gear is mounted on a needle bearing so that it can rotate relative to the planet carrier. Using a needle bearing is useful to counteract tilting of the planet gear relative to the planet carrier.

[0012] For the rotary mounting of the planetary gear on the planet carrier, the planetary gear can have a bolt or pin that is inserted through or into a recess in the planet carrier. Alternatively, the planet carrier can have a bolt or bushing that is inserted through a hole in the planetary gear.

[0013] The planetary gear set can have two or more, for example, three planet gears. The planet gears are all rotatably mounted on the planet carrier. In particular, each planet gear is rotatably mounted on the planet carrier via a needle bearing. All features disclosed in connection with one planet gear are also disclosed for all other planet gears of the planetary gear set.

[0014] According to at least one embodiment, the axial bearing has elongated rolling elements. The longitudinal axes of the rolling elements run, for example, in a radial direction. The rolling elements of the axial bearing can be cylindrical or conical. The axial bearing can be a needle roller bearing. The radial bearing is, for example, a ball bearing.

[0015] According to at least one embodiment, the axial bearing is arranged radially on the outer circumference of the planet carrier. This means that the axial bearing is positioned as far away as possible from the planet carrier's axis of rotation. As a result, the axial bearing has a particularly large span, allowing it to absorb axial forces exceptionally well.

[0016] According to at least one embodiment, the thrust bearing and the planet gear of the planetary gear are at least partially at the same height in the radial direction. In other words, there is a region of the thrust bearing that is radially spaced from the axis of rotation of the planet carrier by the same distance as a region of the at least one planet gear. In particular, the thrust bearing is radially spaced further from the axis of rotation of the planet carrier than the axis of rotation of the planet gear. Alternatively or additionally, the thrust bearing and the ring gear of the planetary gear are at least partially at the same height in the radial direction.

[0017] According to at least one embodiment, the axial play of the planet carrier in the drive device is at most 0.3 mm, 0.2 mm, or 0.1 mm. This means that during operation, the planet carrier can be displaced in a direction parallel to the axis of rotation by at most 0.3 mm, 0.2 mm, or 0.1 mm. Such minimal axial play also keeps the maximum tilt angle of the planet carrier during operation small. This minimal axial play can be achieved, in particular, by a small tolerance chain in the axial direction. For example, axial movement of the planet carrier is limited by stops provided on both sides of the planet carrier.

[0018] According to at least one embodiment, a thrust washer of the axial bearing is located directly opposite a support element of the drive device in the axial direction. The support element forms, for example, one of the two stops mentioned above. For instance, the support element is a section of the housing or is fixed to the housing, that is, immovably arranged relative to the housing. The support element can, in particular, be a radially extending housing section. The thrust washers are the disks of the axial bearing against which the rolling elements of the axial bearing roll.

[0019] The fact that two elements are axially opposed means that, when viewed from a direction parallel to the axis of rotation of the planet carrier, one element at least partially overlaps the other. In other words, the two elements are at least partially at the same height in both the radial and azimuthal directions. The fact that the elements are directly opposed means that, apart from a gap filled with air or lubricant, no other element, and in particular no other solid part of the drive mechanism, is arranged between them.

[0020] According to at least one embodiment, a further thrust washer of the axial bearing is located directly opposite the planet carrier in the axial direction. In particular, the planet carrier is spaced axially away from the support element by the axial bearing.

[0021] According to at least one embodiment, a ring of the radial bearing lies axially directly opposite another support element of the drive device. This second support element forms the other of the two stops mentioned above. The second support element is, in particular, a section of the housing or is fixed to the housing, that is, arranged immovably relative to the housing. The second support element is, for example, a radially extending housing section. The ring is, in particular, the outer ring of the radial bearing. The rolling elements of the radial bearing run on this ring.

[0022] According to at least one embodiment, a further ring of the radial bearing is located directly opposite the planet carrier in the axial direction. This further ring is, in particular, the inner ring of the radial bearing. The further ring can be spaced apart from the planet carrier by an O-ring. The rolling elements of the radial bearing run on this further ring.

[0023] According to at least one embodiment, some or all of the aforementioned, directly opposing elements are adjacent to one another. However, the sum of the axial distances between the aforementioned, directly opposing elements is at most 0.1 mm, 0.05 mm, or 0.02 mm. Because only the thrust bearing and the radial bearing are arranged axially between the planet carrier and the two support elements, the tolerance chain in the axial direction is kept small, resulting in minimal axial play of the planet carrier.

[0024] According to at least one embodiment, the radial bearing is coupled directly to both the planet carrier and the housing of the drive device. In particular, the radial bearing abuts the housing and the planet carrier in a radial direction. For example, the outer ring of the radial bearing abuts the housing in a radial direction, and the inner ring of the radial bearing abuts the planet carrier in a radial direction. In the area where the radial bearing abuts the housing in a radial direction, the housing is, for example, single-walled and forms an outer surface of the drive device with the surface opposite the radial bearing.

[0025] Because the radial bearing borders both the housing and the planet carrier in the radial direction, the tolerance chain in the radial direction is also kept small, which also keeps the maximum tilting angle of the planet carrier small.

[0026] According to at least one embodiment, the planetary gear is arranged axially between the axial bearing and the radial bearing.

[0027] According to at least one embodiment, the radial bearing is located at least partially at the same height as the planet gear in the radial direction. For example, the radial bearing projects radially away from the axis of rotation of the planet carrier and beyond the planet gear. In particular, the radial bearing is located further away from the axis of rotation of the planet carrier than the axis of rotation of the planet gear. Alternatively or additionally, the radial bearing can be located at least partially at the same height as the ring gear of the planetary gear in the radial direction.

[0028] According to at least one embodiment, the inner diameter of the radial bearing is larger than the inner diameter of the axial bearing. For example, the inner diameter of the radial bearing is at least 4 cm or at least 5 cm.

[0029] By positioning the radial bearing far from the axis of rotation, the planet carrier can be precisely aligned and held stably in its radial position during operation. A large radial bearing also helps to counteract tilting.

[0030] According to at least one embodiment, the drive device further comprises an electric motor and an output shaft. The electric motor is coupled to the output shaft via the planetary gear in order to transmit torque from the electric motor to the output shaft.

[0031] In other words, the planetary gear is connected between the electric motor and the output shaft. The planetary gear is specifically designed to increase the torque delivered by the electric motor. For example, the planetary gear is arranged axially between the electric motor and the output shaft.

[0032] The electric motor consists of a stator and a rotor. For example, the electric motor is an internal rotor motor.

[0033] The output is the component of the drive system from which torque is transferred. For example, the output includes an output shaft. The output shaft can be a hollow shaft. For instance, a pedal axle of the drive system might pass through the output shaft. The output shaft can be non-rotatably connected to a chainring or chainring spider. Alternatively or additionally, the output shaft may have an interface for coupling with a chainring or chainring spider.

[0034] According to at least one embodiment, the drive device further comprises a bevel gear stage.

[0035] In particular, the bevel gear stage couples the planetary gear set to the output. In other words, the bevel gear stage is positioned between the planetary gear set and the output. The bevel gear stage is designed, for example, to further increase the torque delivered by the planetary gear set. The bevel gear stage can be a 90° bevel gear stage. The planetary gear set is, for example, arranged axially between the electric motor and the bevel gear stage.

[0036] Due to the coupling of the planetary gear with the bevel gear stage, a high tilting moment and large axial forces can act on the planet carrier during operation of the drive device. These forces are effectively supported by the axial bearing and the radial bearing.

[0037] According to at least one embodiment, the bevel gear stage is coupled to the planet carrier without an intermediate gear stage. In other words, the torque delivered by the planetary gear corresponds to the torque fed into the bevel gear stage. For example, a component of the planetary gear is rotationally fixed to a bevel gear of the bevel gear stage.

[0038] According to at least one embodiment, the radial bearing is arranged axially between the thrust bearing and a second bevel gear of the bevel gear stage. In particular, the radial bearing is arranged at least partially at the level of the planet carrier in the axial direction.

[0039] According to at least one embodiment, the support span of the thrust bearing is greater than the axial distance of the radial bearing to the interface of the bevel gears of the bevel gear stage. This serves, in particular, to keep the axial forces absorbed by the thrust bearing as low as possible. Furthermore, the tilting point of the planet carrier is located close to the radial bearing in the axial direction. By having a smaller axial distance between the radial bearing and the interface of the bevel gears relative to the support span, the lever arm for the force causing the tilting can be kept relatively small. The interface of the bevel gears is understood here to be the area where the teeth of the two bevel gears mesh.

[0040] According to at least one embodiment, the planet carrier is rotationally fixed to a first bevel gear of the bevel gear stage. This means that, during operation, the first bevel gear rotates together with the planet carrier around the planet carrier's axis of rotation at the same speed and in the same direction. The first bevel gear is, in particular, directly connected to the planet carrier, for example, via a positive-locking and / or frictional connection. Alternatively, the planet carrier and the first bevel gear could also be formed integrally. The first bevel gear is, for example, a bevel pinion.

[0041] By coupling the first bevel gear with the planet carrier and providing stable support for the planet carrier using the axial bearing and the radial bearing, the first bevel gear is also mounted with exceptional positional stability, which is advantageous for high power transmission.

[0042] According to at least one embodiment, the bevel gear stage comprises the second bevel gear mentioned above. The second bevel gear engages with the first bevel gear. For example, the second bevel gear is coupled to the output without an intermediate gear stage. An axis of rotation of the second bevel gear runs obliquely or perpendicular to the axis of rotation of the planet carrier or the first bevel gear. The axis of rotation of the output is, for example, parallel to or identical with the axis of rotation of the second bevel gear. In particular, the axis of rotation of the planet carrier lies in a plane that is perpendicular to the axis of rotation of the output. The second bevel gear is, for example, a ring gear. The drive device is, for example, an orthogonal drive.

[0043] According to at least one embodiment, the second bevel gear is coupled to the output via a freewheel. For example, the freewheel couples the second bevel gear to the output shaft of the output.

[0044] According to at least one embodiment, the output shaft of the output device is coupled to a pedal shaft of the drive device via a freewheel. The freewheel is, for example, a toothed pulley freewheel. The pedal shaft is, in particular, guided through the output shaft, which is formed as a hollow shaft.

[0045] According to at least one embodiment, the pedal shaft extends obliquely or perpendicularly to the axis of rotation of the planet carrier. In other words, one axis of rotation of the pedal shaft is oblique or perpendicular to the axis of rotation of the planet carrier. For example, the angle between the pedal shaft, or the axis of rotation of the pedal shaft, and the axis of rotation of the planet carrier is between 80° and 100° inclusive.

[0046] Next, the electric bicycle is specified. The electric bicycle includes a drive device according to one of the embodiments described here.

[0047] Next, the assembly for a drive unit of an electric bicycle and the method for assembling a drive unit are specified. In particular, the assembly is configured for assembling a drive unit according to one of the embodiments described herein. Therefore, all features disclosed in connection with the drive unit are also disclosed for the assembly and the method, and vice versa.

[0048] In at least one embodiment, the assembly for a drive device of an electric bicycle comprises a planet carrier for a planetary gear as well as a radial bearing and an axial bearing for a bearing of the planet carrier such that the planet carrier is rotatable about an axis of rotation.

[0049] The assembly can include, in addition to the planet carrier, the radial bearing, and the thrust bearing, a housing component, for example, a bottom bracket shell. The planet carrier is rotatably mounted relative to this housing component. The housing component of the assembly can be connected to one or more further housing components from one or more other assemblies to form a housing for the drive device. Furthermore, the assembly can include at least one planet gear and one ring gear. The assembly can also include a first bevel gear for a bevel gear stage, which is non-rotatably connected to the planet carrier. Finally, the assembly can include a pedal axle.

[0050] The further assembly includes, for example, an electric motor with a stator, a rotor, and a motor shaft. The further assembly may include the support element for the thrust washer of the axial bearing. Furthermore, the further assembly includes a housing component, for example, a motor housing.

[0051] Another assembly includes, for example, the output shaft and the coupled second bevel gear for the bevel gear stage. Furthermore, yet another assembly includes a housing component, such as a cover.

[0052] In at least one embodiment, the assembly and the further assembly are connected to each other for the assembly of the drive device, in particular by connecting their housing parts. The support element of the further assembly, which is formed, for example, by the further housing part of the further assembly, is arranged axially directly opposite the thrust washer of the axial bearing. The motor shaft can be inserted through the planet carrier during assembly.

[0053] According to at least one embodiment of the method, the assembly is connected to the further assembly. The housing parts of the assembly and the further assembly can be screwed together. Furthermore, the bevel gears of the assembly and the further assembly can be engaged. Additionally, for example, the pedal shaft of the assembly is pushed through the output shaft of the further assembly.

[0054] The following sections provide a more detailed explanation of a drive device, an assembly, a method for assembling a drive device, and an electric bicycle, all described herein, with reference to the drawings and exemplary embodiments. Identical reference numerals indicate identical elements in the individual figures. If elements or components function identically in different figures, their descriptions are not repeated for each subsequent figure. For clarity, elements may not be labeled with corresponding reference numerals in all illustrations.

[0055] They show: Fig. 1 an embodiment of the electric bicycle, Fig. 2 an embodiment of the drive device, Fig. 3 another embodiment of the drive device, Fig. 4 an embodiment of the assembly, Fig. 5 an embodiment of the further assembly, Fig. 6 a position in an embodiment of the assembly method. Fig. 7 an embodiment of the further assembly, Fig. 8 another position in an embodiment of the assembly method.

[0056] Fig. Figure 1 schematically shows an electric bicycle 200 with a bicycle frame 110, which has a lower frame section 120. This forms a down tube. The lower frame section 120 extends towards a bottom bracket of the electric bicycle, the bottom bracket comprising a pedal axle 90. The pedal axle 90 is part of a drive unit 100 installed in the bicycle.

[0057] Fig. Figure 2 shows a first embodiment of the drive device 100 in a cross-sectional view. The drive device 100 has a planetary gear 2. The planetary gear 2 comprises a planet carrier 20, which is rotatably mounted about an axis of rotation A in a housing 7. One or more planet gears 21 are mounted on the planet carrier 20 so as to be rotatable relative to the planet carrier 20. Fig. Figure 2 shows only the part of the drive device 100 above the axis of rotation A.

[0058] The planetary gear set 2 further comprises a sun gear 26. At least one planet gear 21 meshes with the sun gear 26, which, for example, is also mounted to rotate about the axis of rotation A. Furthermore, at least one planet gear 21 meshes with a ring gear 27 of the planetary gear set 2. The ring gear 27 can be mounted to rotate about the axis of rotation A or be fixed to the housing 7, i.e., mounted to prevent rotation.

[0059] The planetary gear 2 couples an electric motor 1 to an output 8. The electric motor 1 comprises a rotor 11 and a stator 12. A motor shaft 10 of the electric motor 1 is non-rotatably connected to the sun gear 26 of the planetary gear 2. Alternatively, the motor shaft 10 could also be non-rotatably connected to the ring gear 27 or the planet carrier 20. The output 8 is non-rotatably connected to the planet carrier 20. In particular, an output shaft 80 of the output 8, which is designed as a hollow shaft 80, is non-rotatably connected to the planet carrier 20 and to a chainring 82 or a chainring spider 82.

[0060] The planetary gear 2 is used in the drive device 100 to transmit torque from the electric motor 1 to the output shaft 8. The planetary gear 2 specifically reduces the rotational speed and increases the torque. The transmitted torque can be used to assist the pedaling motion of the e-bike rider. In this configuration, the pedal shaft 90, to which the rider manually applies torque, is coupled to the output shaft 80 via a freewheel 92, so that both the torque applied by the rider and the torque applied by the electric motor 1 can be transmitted to the output shaft 8.

[0061] The rotary mounting of the planet carrier 20 in the housing 7 is achieved by means of a radial bearing 4 and a thrust bearing 5. The radial bearing 4 comprises an inner ring 42, rolling elements 40, for example in the form of balls, and an outer ring 41. The outer ring 41 abuts the housing 7 in the radial direction. In the axial direction, the outer ring 41 abuts a support element 71 or is arranged at least axially directly opposite it. The inner ring 42 abuts the planet carrier 20 in the radial direction. In the axial direction, the inner ring 42 abuts the planet carrier 20 or is arranged at least axially directly opposite the planet carrier 20.

[0062] A thrust washer 51 of the axial bearing 5, against which the rolling elements 50 of the axial bearing 5 roll, abuts a support element 70 in the axial direction or is at least axially directly opposite the support element 70. The support element 70 is also part of the housing 7. The rolling elements 50 of the axial bearing 5 can be cylindrical or conical. The second thrust washer 52 of the axial bearing 5, against which the rolling elements 50 roll, abuts the planet carrier 20 in the axial direction or is at least directly opposite the planet carrier 20.

[0063] The described arrangement minimizes the tolerance range for the radial and axial play of the planet carrier 20. For example, the axial play of the planet carrier 20 is at most 0.3 mm. This minimizes or prevents tilting of the planet carrier 20 within the housing.

[0064] Fig. Figure 3 shows a further embodiment of the drive device 100 in a cross-sectional view. The drive device 100 comprises a housing 7 with three interconnected housing parts 70, 71, 74. Housing part 70 forms a motor housing in which an electric motor 1 is accommodated. Housing part 71 forms a bottom bracket housing in which, among other things, a planetary gear 2 is accommodated. The motor housing 70 and the bottom bracket housing 71 are connected to each other via a sealing sleeve 72. Housing part 74 forms an output-side cover that is screwed onto the bottom bracket housing 71.

[0065] The electric motor 1 comprises a stator 12 and a rotor 11. The electric motor 1 is an internal rotor motor. During operation, the rotor 11 rotates relative to the stator 12, or rather to the housing 7, about an axis of rotation A. The rotor 11 is coupled to a motor shaft 10 and, during operation, also sets the shaft into rotation about the axis of rotation A. The axis of rotation A passes through the motor shaft 10. The motor shaft 10 is made, for example, of stainless steel or case-hardened steel. The electric motor 1 is mounted in the housing 7 by means of motor bearings 16.

[0066] The motor shaft 10 projects axially out of the rotor 11 and into the planet carrier 20 of the planetary gear 2. In the opposite axial direction, a magnet 14 is arranged at the end of the motor shaft 10, spaced apart from the motor shaft 10 by an adapter 15. The adapter 15 is made of aluminum, for example, and is intended to reduce the influence of the steel motor shaft 10 on the magnetic field generated by the magnet 14. The drive device 100 further includes a sensor (not shown) that detects the magnetic field of the magnet 14 and thereby qualitatively and quantitatively determines the position of the motor shaft 10.

[0067] The planetary gear 2, which forms a first gear stage of the drive device 100, comprises the planet carrier 20, three planet gears 21, a sun gear 26 and a ring gear 27. In the Fig. Figure 3 shows a cross-sectional view of a first planet gear 21, namely the one located above the axis of rotation A, while another planet gear 21 is shown in a top view. The planet gears 21 are rotatably mounted on the planet carrier 20. The planet carrier 20 is also rotatably mounted about the axis of rotation A by means of two rolling bearings 4, 5. In this case, the planet carrier 20 has bushings 25 that are inserted through holes in the planet gears 21.

[0068] The sun gear 26 for the planetary gear set 2 is integrated into the motor shaft 10; that is, the motor shaft 10 and the sun gear 26 are formed as a single piece. Specifically, the teeth for the sun gear 26 are formed in the motor shaft 10 by means of a forming process, for example, a rolling process. This means that the teeth for the sun gear 26 are manufactured without milling, as can be seen from the absence of milling marks. The teeth of the sun gear 26 are helical, meaning that the teeth are not parallel, but rather angled to or helically around the axis of rotation A.

[0069] The teeth of the sun gear 26 engage with corresponding helical teeth of the planet gears 21. Rotation of the motor shaft 10 sets the planet gears 21 into rotation, which in turn causes the planet carrier 20 to rotate around the axis of rotation A. The planet gears 21 roll against the stationary ring gear 27. The ring gear 27 is fixed, for example, to the housing 7 and therefore does not rotate relative to the housing 7 during operation.

[0070] The use of a forming process in the manufacturing of the sun gear 26's teeth results in a particularly smooth surface. The teeth of the planet gears 21, for example, are made of plastic. The smooth surface of the sun gear 26 is especially advantageous when using plastic for the planet gears 21, as it minimizes wear. Planet gears made entirely or partially of plastic tolerate larger manufacturing tolerances and are less susceptible to tilting relative to the planet carrier 20.

[0071] In fact, a tilting moment acts on the planet gears 21, which tends to tilt them relative to the planet carrier 20. This tilting moment results largely from the use of helical gearing. However, helical gearing is advantageous with regard to high power transmission and low noise generation.

[0072] To minimize and effectively counteract tilting of the planet gears 21 relative to the planet carrier 20, each planet gear 21 is rotatably mounted on the planet carrier 20 by means of a needle bearing 22. The needle- or cylindrical-shaped rolling elements 24 of the needle bearing 22 roll on the bushings 25 on one side and on sleeves 23 on the other. The bushings 25 and the sleeves 23 are made of metal, for example. The sleeves 23 are part of the planet gears 21 and are encased or overmolded with plastic, with the teeth of the planet gears 21 being formed from this plastic. By reducing the relative tilting between the planet gears 21 and the planet carrier 20 through the use of the needle bearings 22, the wear of the drive device 100 can be reduced and its performance increased.

[0073] The planet carrier 20 has a recess at one axial end facing away from the motor 1. The axis of rotation A passes through this recess. The planet carrier 20 has an internal thread in the area of ​​the recess. A first bevel gear 30, namely a bevel pinion, of a bevel gear stage 3 is screwed into this internal thread. The bevel gear stage 3 forms a second gear stage of the drive device 100. The first bevel gear 30 has a cylindrical section with an external thread and a conical section with external teeth. The cylindrical section is screwed into the recess of the planet carrier 23, thereby fixing the first bevel gear 30 to the planet carrier 23 and making it immovable relative to the planet carrier 20, i.e., rotationally fixed to it. The first bevel gear 30 is precisely aligned relative to the planet carrier 20 by means of a centering collar.The cone-shaped section protrudes axially, away from the electric motor 1, from the planet carrier 20.

[0074] The first bevel gear 30 has a recess that is open towards the electric motor 1 and into which the motor shaft 10 is guided. The motor shaft 10 can rotate freely within this recess. Unlike in the Fig. As shown in Figure 3, the motor shaft 10 could be rotatably mounted within the recess by means of a bearing.

[0075] The section of the motor shaft 10 projecting into the recess of the bevel gear 30 is free of teeth. This section forms, for example, an interface for a so-called "stand-alone" test of the electric motor 1, that is, a test in its uninstalled state.

[0076] In operation, the planet carrier 20 and the first bevel gear 30 rotate together around the axis of rotation A. The bevel gear stage 3 has a second bevel gear 31 in the form of a ring gear. The second bevel gear 31 is mounted to rotate around a pedal axle P, the pedal axle P being perpendicular to the axis of rotation A. Bevel gear stage 3 is therefore a 90° bevel gear stage.

[0077] The second bevel gear 31 is coupled via a freewheel 81 to an output shaft 80 in the form of a hollow shaft. The output shaft 80 is part of an output 8. The output 8 also includes, for example, a chainring and / or a chainring spider (not shown), which are rotationally fixed to the output shaft 80. Alternatively, the output shaft 80 can also simply have an interface for a rotationally fixed coupling with the chainring or the chainring spider.

[0078] A pedal shaft 90 extends through the hollow-shafted output shaft 80. The pedal shaft 90 is coupled to the output shaft 80. Both the pedal shaft 90 and the output shaft 80 are rotatably mounted by radial bearings 60, 61, the so-called main bearings 60, 61. When the rider of the electric bicycle pedals, the pedal shaft 90 is set into rotation about the pedal axis P, thereby engaging the output shaft 80 via a freewheel mechanism. The electric motor 1 exerts a torque on the output shaft 80, assisting the rider, via the planetary gear 2 and the bevel gear stage 3. The drive device 100 shown is an orthogonal drive.

[0079] By using a bevel gear stage 3 directly coupled to the planet carrier 20, i.e., without any further, intermediate gear stage, the drive device 100 can be designed to be particularly compact and simultaneously provides an efficient speed reduction from the electric motor 1 to the output 8. However, the direct coupling between the planet carrier 20 and the bevel gear stage 3 also results in the bevel gear stage 3 exerting an axial force, a radial force, and an azimuthal force on the planet carrier 20 during operation of the drive device 100. These forces attempt to push the planet carrier 20 towards the electric motor 1 and simultaneously tilt the planet carrier 20.

[0080] To efficiently absorb the radial forces acting upon it, the planet carrier 20 is mounted in the housing 7 via a large radial bearing 4. The radial bearing 4 has, for example, an inner diameter of 5 cm. The radial bearing 4 is supported by the planet carrier 20.

[0081] The axial forces that occur are absorbed by a thrust bearing 5. In particular, the tilting moment results in a large axial load on the thrust bearing 5. The thrust bearing 5 also has a large diameter. Here, the thrust bearing 5 is arranged at the outer edge or outer circumference of the planet carrier 20, radially as far away as possible from the axis of rotation A. In addition, elongated rolling elements, such as cylinders or cones, are used as the rolling elements 50 of the thrust bearing 5, which distributes the load over a larger area.

[0082] To minimize tilting of the planet carrier 20, the axial play for the planet carrier 20 between the radial bearing 4 and the thrust bearing 5 is selected to be particularly small, for example, a maximum of 0.1 mm. This is achieved, among other things, by a small tolerance chain in the axial direction. The small tolerance chain is implemented as follows: One thrust washer 51 of the thrust bearing 5, against which the rolling elements 52 roll, is arranged in the axial direction directly opposite a support element, namely a radially extending part of the motor housing 70. The other thrust washer 52 of the thrust bearing 5 is arranged in the axial direction directly opposite the planet carrier 20.Furthermore, the inner ring 42 of the radial bearing 4, on which the rolling elements 40 of the radial bearing 4 roll, is arranged axially directly opposite the planet carrier 20, and the outer ring 41 of the radial bearing 4 is arranged axially directly opposite another support element, namely a part of the bottom bracket housing 71. The motor housing 70 and the bottom bracket housing 71 are axially immovably connected to each other. The elements directly opposite each other axially either abut each other or are separated from each other in the axial direction by at most narrow gaps. In particular, the sum of the axial distances between the aforementioned directly opposite elements is less than 0.1 mm.

[0083] With the drive device 100 installed and the motor running, the planet carrier 20 is pressed axially towards the electric motor 1. The planet carrier 20 is then supported axially directly against the thrust washer 52, and the thrust washer 51 is supported axially directly against the motor housing 70. The aforementioned small axial distances ensure that the planet carrier 20 hardly tilts despite the strong tilting moment.

[0084] Another measure to reduce tilting of the planet carrier 20 is to ensure minimal radial play between the planet carrier 20 and the first bevel gear 30. For this purpose, the first bevel gear 30 is rigidly connected to the planet carrier 20. The radial play of the planet carrier 20 is kept low because the radial bearing 4 used for the radial support of the planet carrier 20, which is arranged radially between the planet carrier 20 and the housing 7, has its inner ring 42 in contact with the planet carrier 20 and its outer ring 41 with the housing 7. No intermediate elements are used between the radial bearing 4 and the housing 7, as these could increase the radial play of the planet carrier 20 or the first bevel gear 30. In other words, by using fewer elements in the radial tolerance chain, the radial play of the first bevel gear 30 and the planet carrier 20 is kept low.Tilting the planetary carrier 20 is therefore only possible to a limited extent.

[0085] Overall, the use of the described radial bearing 4 and the described axial bearing 5 helps to counteract tilting of the planet carrier 20 and to efficiently absorb the acting forces. This results in particularly high performance of the drive device 100 with simultaneously low wear.

[0086] Performance is further enhanced by the precise alignment of the bevel gears 30 and 31 relative to each other. This is achieved, firstly, by the previously described low-backlash bearing arrangement of the planet carrier 20 and the first bevel gear 30, and secondly, by the low-backlash bearing arrangement of the second bevel gear 31. For this purpose, the second bevel gear 31 is rigidly connected to the output shaft 80. The output shaft 80, in turn, is rotatably mounted about the axis of rotation P via the radial bearing 60, which is in direct contact with the output shaft 80 on one side and with the cover 74 on the other. The cover 74 is rigidly connected to the bottom bracket shell 71.Here too, to reduce the play of the second bevel gear 31 in the axial direction, parallel to the axis of rotation A, a rotatable bearing of the second bevel gear 31 around the axis of rotation P with few moving elements between the housing 7 and the second bevel gear 31 is implemented.

[0087] The fixed connection between the housing parts 71 and 74 is a screw connection. For this screw connection, the bottom bracket housing 71 and the cover 74 have threads 710 and 740, respectively, which interlock. These threads 710 and 740 extend around the axis of rotation P of the pedal axle 90. The relative arrangement between the housing parts 71 and 74 is secured by means of clamping elements 742. In this case, the clamping elements 742 are screws that are screwed into receptacles 741 of the housing part 74. Specifically, the housing part 74 has two annular sections 743 and 744, which, in the illustrated cross-sectional view, are formed by a U-shaped area of ​​the third housing part 74, i.e., they are spaced apart from each other by a gap parallel to the axis of rotation P. The two sections 743 and 744 each form part of the external thread 740 of the housing part 74.The screwed-in screws 742 push the second section 744 away from the first section 743 with a longitudinal end, causing the screw connection to jam between the housing parts 71, 74 and thus fixing them in their relative arrangement to each other.

[0088] The second bevel gear 31 is restricted in its movement relative to the third housing element 74 in a direction parallel to the axis of rotation P by means of stop surfaces. The screw connection between the housing parts 71 and 74 therefore allows the second bevel gear 31 to be positioned particularly precisely along the axis of rotation P. The tightening of the screw connection then ensures a particularly stable position of the second bevel gear 31 in the direction of the axis of rotation P. Overall, the bevel gears 30 and 31 are thus aligned with particular precision relative to each other, which benefits the performance of the entire drive device 100.

[0089] Fig. Figure 4 shows an embodiment of assembly 101 for the drive device of the Fig. 3. Assembly 101 comprises the bottom bracket housing 71, the planet carrier 20, and the first bevel gear 30, which are rotationally fixed to one another and are rotatably mounted by means of the radial bearing 4 supported by the planet carrier 20. Assembly 101 further comprises the planet gears 21, which are rotatably mounted on the planet carrier 20 by means of the needle bearings 22. The axial bearing 5 is located on the side of the planet carrier 20 facing away from the first bevel gear 30. The pedal axle 90 is also inserted through the bottom bracket housing 71. The bottom bracket housing 71 is, for example, made of metal. Here, the bottom bracket housing 71 is formed in one piece and encloses both the pedal axle 90 in the direction around the pedal axis P and the planet carrier 20 in the direction around the axis of rotation A.

[0090] Fig. Figure 5 shows an embodiment of the further assembly 102 for the drive device 100 of the Fig. 3. The assembly 102 comprises the motor housing 70, in which the electric motor 1 with the associated motor shaft 10 is accommodated.

[0091] For the assembly of the drive device 200 of the Fig. 3. First, assembly 102 is plugged together with assembly 101. The resulting device is in Fig. Figure 6 shows that during assembly, the motor shaft 10 is pushed through the planet carrier 20 and into the receptacle of the first bevel gear 30. The thrust washer 51 is positioned axially directly opposite a radially extending section of the motor housing 70. The housing parts 70 and 71 are then joined together. The dimensions of the individual elements are selected such that no or only small air gaps occur in the axial direction between the housing sections, against which the bearings 4 and 5 can be axially supported.

[0092] Fig. Figure 7 shows an embodiment of the further assembly 104 for the assembly of the drive device 100 of the Fig. 3. Assembly 104 comprises housing part 74. The clamping elements 742, in the form of screws, are already inserted into the receptacles 741 of housing part 74, but only to the extent that sections 743 and 744 are not yet clamped against each other. Assembly 104 further comprises the bevel gear 31, the output shaft 80, and the radial bearing 60. The bevel gear 31 and the output shaft 80 are rotatably mounted about the axis of rotation P via the radial bearing 60.

[0093] For the assembly of the drive device, assembly group 104 of the Fig. 7 on the device of the Fig. 6 screwed on (see Fig.8) The pedal shaft 90 is pushed through the opening 745 in the housing part 74. The housing parts 74 and 71 are screwed together until the positioning of the bevel gears 30 and 31 parallel to the axis of rotation P is adjusted as desired. The screws 742 are then tightened, which clamps the sections 743 and 744 against each other and thus secures the screw connection between the housing part 74 and the housing part 71. This fixes the bevel gears 30 and 31 in their relative position parallel to the axis of rotation P. Reference symbol list 1 electric motor 2 planetary gears 3 bevel gear stage 4 radial bearings 5 axial bearings 7 cases 8 Drive 10 Motor shaft 11 Rotor 12 Stator 14 Magnet 15 adapters for magnets 16 engine mounts 20 planetary carriers 21 planetary gear 22 needle bearings 23 Outer sleeve 24 rolling elements 25 Bushing / Bolt 26 sun wheel 27 Ring gear 30 first bevel gear / pinion 31 second bevel gear / ring gear 40 rolling elements 41 Outer ring 42 inner ring 50 rolling elements 51 Thrust washer 52 Thrust washer 60 radial bearings 61 radial bearings 70 Engine housings 71 Bottom bracket shell 72 Sealing sleeve 74 Coverage 80 Output shaft 81 Freewheel 82 chainring / chainring spider 90 Pedal shaft 92 Freewheel 100 drive device 101 Assembly 102 Assembly 104 Assembly 110 bicycle frames 120 down tube 200 electric bicycle 710 thread 740 thread 741 recording 742 Fixing element / screw 743 first section 744 second section 745 Implementation A axis of rotation P Pedal axle / rotation axle

Claims

[1] comprising a drive device (100) for an electric bicycle (200) - a planetary gear (2) with a planet carrier (20), wherein - the planet carrier (20) is rotatably mounted about an axis of rotation (A) by means of a radial bearing (4) and an axial bearing (5). [2] Drive device (100) according to claim 1, wherein - the axial bearing (5) has elongated rolling elements (50). [3] Drive device (100) according to claim 1 or 2, wherein - the axial bearing (5) is arranged in a radial direction at the outer edge of the planet carrier (20). [4] Drive device (100) according to one of the preceding claims, wherein - the axial play of the planet carrier (20) in the drive device (100) is at most 0.3 mm. [5] Drive device (100) according to one of the preceding claims, wherein - a thrust washer (51) of the axial bearing (5) is located directly opposite a support element (70) of the drive device (100) in the axial direction, - another thrust washer (52) of the axial bearing (5) is located directly opposite the planet carrier (20) in the axial direction, - a ring (41) of the radial bearing (4) is axially directly opposite a further support element (71) of the drive device, - another ring (42) of the radial bearing (4) is located directly opposite the planet carrier (20) in the axial direction. [6] Drive device (100) according to one of the preceding claims, wherein - the radial bearing (4) is coupled both directly to the planet carrier (20) and directly to a housing (7) of the drive device (100). [7] Drive device (100) according to one of the preceding claims, further comprising - a planet gear (21) which is rotatably mounted on the planet carrier (20), wherein - that at least one planet gear (21) is arranged axially between the axial bearing (5) and the radial bearing (4). [8] Drive device (100) according to one of the preceding claims, wherein - the inner diameter of the radial bearing (4) is larger than the inner diameter of the axial bearing (5). [9] Drive device (100) according to one of the preceding claims, further comprising - an electric motor (1), - a drive (8) - the electric motor (1) is coupled to the output (8) via the planetary gear (2) in order to transmit a torque from the electric motor (1) to the output (8). [10] Drive device (100) according to claim 9, further comprising - a bevel gear stage (3) between the planetary gear (2) and the output (8), wherein - the bevel gear stage (3) is coupled to the planetary gear (2) without an intermediate gear stage. [11] Drive device (100) according to claim 10, wherein - the radial bearing (4) is arranged axially between the axial bearing (5) and a second bevel gear (31) of the bevel gear stage (3). [12] Drive device (100) according to claim 10 or 11, wherein - the support span of the axial bearing (5) is greater than the axial distance of the radial bearing (4) to the interface of the bevel gears (30, 31) of the bevel gear stage (3). [13] Drive device (100) according to one of claims 10 to 12, wherein - the planet carrier (20) is coupled to a first bevel gear (30) of the bevel gear stage (3) in a rotationally fixed manner. [14] Drive device (100) according to claim 13, wherein - the second bevel gear (31) engaging with the first bevel gear (30) is coupled to the output (8) without an intermediate gear stage. [15] Assembly (101) for a drive device (100) of an electric bicycle (200) comprising - a planet carrier (20) for a planetary gear (2), - a radial bearing (4) and an axial bearing (5) for a bearing of the planet carrier (20) rotatable about an axis of rotation (A).

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