Electric bicycle drive unit with interlocking support member for use in powertrain assembly and assembly method

Abstract

The proposed solution particularly relates to a drive unit (A) for an electric bicycle. The drive unit includes at least one electric motor drive (R, S), a bottom bracket spindle assembly (T), and a powertrain assembly (1) that transmits the drive torque generated by the electric motor drive (R, S) to an output member (92) of the bottom bracket spindle assembly (T). The powertrain assembly (1) has a powertrain carrier (10) to which at least two interacting transmission members (32, 42) are rotatably mounted. One of the transmission members (32, 42) is attached to the powertrain carrier via a support member (5) so as to be rotatable about a rotation axis (M). A first end (52) of the support member is inserted into a part (101) of the powertrain carrier (10) in a rotationally fixed manner, and a second end (50) of the support member defines the axial position of the one transmission member (42) on the powertrain carrier (10) relative to the rotation axis (M). A central portion (51) for rotatably mounting one transmission member (42) is provided between the first end portion (52) and the second end portion (50).

Description

[Technical Field]

[0001] The proposed solution relates in particular to drive units for electric bicycles. [Background technology]

[0002] Electric bicycle drive units are widely known, each of which includes at least one electric motor drive unit. The at least one electric motor drive unit is used to apply a drive torque generated by external force applied to an output member of the drive unit. The output member is connected to a power transmission member connected to the rear wheel of the electric bicycle via a transmission medium such as a belt or chain. The drive torque generated by external force is typically applied in addition to a drive torque generated by muscle force applied to the pedal shaft via the pedals.

[0003] The output member and the power transmission member are usually mounted on a pedal shaft assembly that includes a pedal shaft with a freewheel, which allows the rotation axis of the pedal shaft to be the same as that of the output member and the power transmission member, making it possible to reduce the size of the drive unit.

[0004] There is still a demand for electric bicycle drive units that are lighter in weight, have higher power density, and / or are easier to install. Summary of the Invention [Problem to be solved by the invention]

[0005] In view of this background, a drive unit has been proposed that includes a powertrain assembly including a powertrain carrier on which at least two interacting transmission members are rotatably supported, in order to transmit the drive torque generated by the electric motor drive to the output member of the pedal shaft assembly. One of these transmission members is rotatably supported on the powertrain carrier about a rotation axis via a support member, and the support member is a) the first end is rotationally fixedly engaged with a portion of the powertrain carrier; b) determining an axial position of one transmission member on the powertrain carrier relative to the rotation axis by the second end; c) A central portion is provided between the first end and the second end for rotatably supporting one transmission member.

[0006] In the proposed drive unit, the radial and axial positioning of at least one transmission member is performed via a power train assembly with a support member. The corresponding functional integration not only facilitates the assembly of the power train assembly, but also the assembly of the drive unit. Furthermore, the individual assemblies of the drive unit can be preassembled and then combined to form the drive unit more easily.

[0007] The support member provided in the powertrain assembly of the proposed drive unit securely fixes the support member to the powertrain carrier by its first end. The central portion between the first and second ends of the support member defines the rotation axis of the transmission member, and the transmission member is fixed in axial position by the second end. Thus, the axial position of the rotatable transmission member on the powertrain carrier is fixed by the second end. Because one support member accurately positions the transmission member on the powertrain carrier, it also ensures accurate positional relationship with other transmission members on the interacting powertrain carrier. In particular, in a preferred embodiment, no additional parts need to be assembled to the powertrain carrier after the support member is attached to the powertrain carrier.

[0008] For example, the first end of the support member may be press-fit into an opening formed in a portion of the powertrain carrier. The support member, which defines the axis of rotation of the transmission member, is securely fixed by a press-fit connection between the portion of the powertrain carrier and the first end of the support member. The first end being press-fit into the opening in the powertrain carrier further simplifies assembly.

[0009] For example, a shoulder may be formed at the second end, and the axial position of the rotatably supported transmission member may be determined via this shoulder. If a shoulder is formed at the second end of the support member, when the support member is assembled, this shoulder may axially abut against the rotatably supported transmission member or a component rotationally fixedly connected to the transmission member, thereby determining the axial position of the transmission member on the powertrain carrier. For example, the transmission member may be rotatably supported on the central portion of the support member via a bearing whose inner ring is rotationally fixedly connected to the central portion. For example, in this way, the shoulder at the second end may axially abut against the inner ring of a bearing designed as a roller bearing or the like.

[0010] In this configuration, the axial length of the central portion may be shorter than the axial length of the inner ring so that the inner ring of the bearing is securely fixed and clamped in the axial direction by the shoulder of the second end when the support member is inserted. As a result, the width of the inner ring along the rotation axis is longer than the length of the central portion along the rotation axis. This allows the surface of the inner ring away from the shoulder of the second end to be pressed against a portion of the power train carrier by the shoulder of the second end, thereby fixing it in the axial direction. In this way, by inserting the support member, the inner ring can be fixed along the rotation axis between the shoulder of the second end and a portion of the power train carrier.

[0011] In one embodiment, the transmission member rotatably supported via the support member is formed by an annular gear. To optimize weight, the annular gear can be rotationally fixedly connected to a hub, which is further fixed to the outer ring of the bearing. The outer ring is rotatably supported relative to the inner ring, for example, via a number of roller bodies. By providing the hub between the outer ring of the bearing and the annular gear, which are formed by additional components, it is not necessary to form the gear as a single piece using a heavy or expensive material. For example, only the annular gear can be made from high-strength steel, while the hub can be made from a lighter aluminum material. The lightweight hub is press-fit onto the annular gear or a gear ring formed integrally therewith, via a fitted adjustment, and is then connected to the outer ring of the bearing.

[0012] In one embodiment, the first end, the central portion, and the second end of the support member are formed with different diameters. The diameter of the second end is larger than the diameter of the central portion, which is larger than the diameter of the first end. Such a (stepped) support member configuration allows, for example, the support member to be inserted into the transmission member and supported rotatably along the rotation axis with the first end leading. In particular, in this configuration, the support member may be formed as a hollow stepped bolt, in particular, with an outer diameter that increases stepwise from the first end through the central portion to the second end.

[0013] The first end of the support member is fitted and fixed to a portion of the powertrain carrier for at least radial support, while in one embodiment the second end may be radially supported by a support shield. Such a support shield is fixed to the powertrain assembly and form-fittingly connected to the second end. For example, the support shield may have a support opening that form-fits the second end. Optionally, the second end may protrude through a corresponding opening in the support shield.

[0014] If a portion of the second end protrudes through the support opening formed in the support shield, in a further development, the protruding portion of the second end can be accommodated in a receiving portion provided in a housing portion of the drive unit that accommodates the electric motor drive and the power train assembly provided with the support shield. The receiving portion can be formed, for example, on the corresponding portion of the housing, i.e., on the inside facing the housing space of the housing that accommodates the electric motor drive and the power train assembly including the support shield. When assembling the drive unit, first, the electric motor drive, the power train assembly, and the support shield are assembled into the first housing portion. Then, the housing space is closed by the second housing portion, and the second housing portion is provided with a receiving portion that accommodates the protruding portion of the second end. In this way, the second housing portion and, if necessary, the drive unit housing can radially support the support member of the second end (additionally). This allows for further strengthening of the support member that provides the rotation axis of the transmission member without increasing the complexity of the drive unit assembly.

[0015] In principle, the at least two transmission members rotatably supported on the transmission carrier and interacting with each other may be of different types, such as friction wheels or belt pulleys. In one embodiment, the mutually interacting transmission members are gears. For example, a stepped gear (first transmission stage) may be rotatably supported on the transmission carrier and meshes with a pinion on the rotor shaft of the rotor assembly of the electric motor drive. This stepped gear is then rotationally fixedly coupled to a stepped pinion, which is the first transmission member (second transmission stage) of the transmission assembly. An intermediate gear meshing with the stepped pinion may be provided as a second transmission member fixed to the transmission carrier via a support member.

[0016] The intermediate gear meshes with the output gear of the pedal shaft assembly to transmit the driving torque generated by the motor to the power transmission member, and when the drive unit is attached to an electric bicycle, transmits the driving force to the rear wheel of the electric bicycle via a belt or chain.

[0017] In one variant, the stepped gear and stepped pinion of the powertrain assembly are rotationally fixedly connected to a support shaft, which is rotatably supported via a (first) bearing mounted on the powertrain carrier. The support shaft may, for example, be formed integrally with the stepped pinion, with one shaft end being press-fit into the shaft opening of the stepped gear. Other configurations are of course possible. For example, the stepped pinion may be formed as a separate part and assembled to the support shaft.

[0018] In one embodiment, a stepped gear of a two-stage gear transmission provided on a transmission assembly includes an externally toothed ring gear and a hub, and the ring gear is connected to the hub of the stepped gear via a carrier structure having multiple through-holes. Thus, the stepped gear can be formed as a single unit with the hub and ring gear. However, to optimize rigidity, weight, and / or operating noise, in this embodiment, several through-holes are formed in the carrier structure connecting the hub to the ring gear. The multiple through-holes in the carrier structure not only reduce weight but also help reduce airborne noise. Airborne noise can, in some circumstances, cause unpleasant operating noise for a user during operation of the drive unit, especially if the airborne noise also vibrates the housing of the drive unit. Furthermore, the carrier structure having multiple through-holes significantly reduces the weight of the stepped gear.

[0019] In a further development, the through openings are dimensioned in such a way that the carrier structure is ultimately constituted only by a plurality of carrier parts that extend in spoke-like fashion (for example in the form of radial struts) from the hub to the ring gear.

[0020] Alternatively, the through openings may be arranged in a series within the carrier structure in a circumferential row around the axis of rotation of the stepped gear, for example, the through openings may be arranged in a circular series around the axis of rotation of the stepped gear, and, if desired, the through openings may be equally spaced apart.

[0021] In a design further optimizing stiffness and / or airborne noise, the through-openings may not be circular, but may be at least partially curved or have an arrow-shaped profile. This means that the rotation direction of the stepped gear is specified during operation of the drive unit in order to transmit the drive torque generated by the electric motor drive in the direction of the output member of the pedal shaft assembly. Each through-opening may have a shape such that the opening edges, which are circumferentially opposite to each other and extend from the hub toward the ring gear (center), are curved or split in the direction opposite to the rotation direction, for example.

[0022] To further integrate the functionality of the powertrain assembly into the powertrain carrier, in one embodiment, the powertrain carrier may comprise a support to which at least a portion of the electronic assembly of the drive unit is fixed. Thus, the powertrain carrier may, for example, form a support for fixing an electronic assembly within the drive unit housing, away from the area where the rotatable transmission member is supported on the powertrain carrier. For example, this support may serve to fix at least a portion of at least one circuit board of the electronic assembly of the drive unit. Thus, in the assembled state, at least a portion of the circuit board is fixed to the support on the powertrain carrier. Such a circuit board may, for example, be part of the control electronics for controlling the electric motor drive.

[0023] The proposed solution also relates to a method for assembling a drive unit for an electric bicycle. In a drive unit assembled according to the proposed assembly method, a powertrain assembly with a powertrain carrier is accommodated together with an electric motor drive in a housing of the drive unit, in which a pedal shaft assembly is also rotatably supported. In the proposed assembly method, the powertrain assembly is pre-assembled, including at least two transmission members rotatably supported on the powertrain carrier and interacting as a structural unit. This pre-assembled structural unit is then mounted in a housing part of the housing that already includes at least the stator of the electric motor drive.

[0024] Therefore, in this aspect of the proposed solution, the power train assembly is pre-assembled, so that the functionality of the power train assembly may be tested individually before it is assembled into the housing part by fixing the power train carrier to the housing part in which at least the stator of the electric motor drive part is already mounted.

[0025] The pre-assembled power train assembly may include a two-stage gear type power train, in which, for example, a stepped gear, a stepped pinion as a first transmission member of the power train assembly rotationally fixedly coupled to the stepped gear, and an intermediate gear as a second transmission member of the transmission unit meshing with the stepped pinion are pre-assembled in a state where they are rotatably supported on the power train carrier of the power train assembly. The stepped gear is arranged to mesh with the pinion of the rotor shaft of the electric motor drive.

[0026] The power train assembly can generally be pre-assembled using the support member according to the first aspect described above, which makes it even easier, and therefore the advantages and features described above and below in relation to embodiments of the proposed drive unit are also applicable to embodiments of the proposed assembly method.

[0027] If a predetermined support member is provided, this support member may be assembled to a transmission member already arranged on the transmission carrier, whereby its first end may be guided through the transmission member and inserted into a part of the transmission carrier. If the transmission member rotatably supported on the transmission carrier via a support member is formed by the aforementioned intermediate gear, in one embodiment of the proposed assembly method, the support member is fitted (in a pre-assembly step) to the intermediate gear already arranged on the transmission carrier and brought into mesh with the stepped pinion.

[0028] Before the pre-assembled power train assembly is assembled into the housing part, a rotor assembly with a rotor shaft may already be assembled into the housing part with the stator. The rotor shaft of the rotor assembly is mounted with, for example, a pinion that meshes with the stepped gear of the power train assembly. The power train carrier of the pre-assembled power train assembly has, at its end facing the electric motor drive, an opening for passing, for example, the pinion of the rotor shaft. This allows the pre-assembled power train assembly to be assembled into the housing part already supporting the stator and the rotor with the pinion shaft, and the pinion of the rotor shaft to mesh with the stepped gear that is already rotatably supported on the power train carrier.

[0029] In another embodiment, the rotor assembly with the rotor shaft may be pre-assembled to the powertrain assembly, and the pre-assembled powertrain assembly together with the rotor assembly may be assembled to the housing part already comprising the stator of the electric motor drive. Thus, for example, the pinion of the rotor shaft is already arranged in a predetermined state on the powertrain assembly outside the housing part comprising the stator so as to already mesh with the stepped gear of the powertrain assembly, and therefore the powertrain assembly and the rotor assembly may be assembled as a pre-assembled assembly to the housing part already accommodating the stator.

[0030] Typically, a support shield can also be assembled to the powertrain carrier. The support shield can be assembled to the powertrain carrier before or after the powertrain assembly is assembled to the housing part already comprising the stator of the electric motor drive. This support shield can, for example, enable the formation of a form-fitting receptacle for the second end of the above-mentioned support member. Alternatively or additionally, the support shield can accommodate a (second) bearing, in particular a roller bearing, via which the support shaft of the stepped gear assembly is rotatably supported, the stepped gear meshing with the pinion of the rotor shaft and the stepped pinion of the powertrain assembly being rotationally fixedly connected to the stepped gear.

[0031] In one embodiment of the proposed assembly method, for inserting the electronic assembly of the drive unit, at least a part of the electronic assembly, for example at least a part of a circuit board of the electronic assembly, can be fixed to a support of the powertrain carrier of the powertrain assembly, for example by fixing a part of the electronic assembly to a support of the powertrain carrier after the powertrain assembly has been placed in a predetermined position in the housing space of the yet unclosed drive unit housing.

[0032] The pedal shaft assembly can be assembled into the (first) housing part before the housing space in which the electric motor drive and the powertrain assembly are (completely) accommodated is closed by another (second) housing part of the housing. During this assembly, the first housing part already includes at least the stator of the electric motor drive. The two housing parts that are fixed together in the assembled drive unit each have a pedal shaft opening for the pedal shaft of the pedal shaft assembly. This allows pedals to be attached to each end protruding from the housing (and also allows the power transmission member of the pedal shaft assembly to be connected to a belt or chain on the other side of the housing). [Brief explanation of the drawings]

[0033] The accompanying drawings show examples of possible implementations of the proposed solution. [Figure 1A] 1 shows a view of the first housing part of the housing of the proposed drive unit from the outside. [Figure 1B] 1B shows the housing part of FIG. 1A rotated by 180° to view the inside, with the stator of the electric motor drive already inserted in the motor support position provided for it; FIG. [Figure 2] 1A and 1B during assembly of the drive unit before the rotor assembly of the electric motor drive is inserted. FIG. [Figure 3] FIG. 10 is a view showing the first housing part with the rotor assembly inserted in a predetermined state. [Figure 4] 4 shows the first housing part shown in FIG. 3, a power train assembly fixed thereto and coupled to a pinion of the rotor shaft of the electric motor drive, and a support shield at least partially covering the transmission member of the power train assembly. [Figure 5] FIG. 10 shows the first housing part with the power train assembly assembled and the support shield secured thereto. [Figure 6] FIG. 6 is an exploded view of an intermediate gear assembly of the powertrain assembly shown in FIGS. 4 and 5, which is part of a second transmission stage of a two-stage transmission of the powertrain assembly. [Figure 7A] 10A-10C illustrate various stages in pre-assembly of a powertrain assembly. [Figure 7B] 10A-10C illustrate various stages in pre-assembly of a powertrain assembly. [Figure 7C] 10A-10C illustrate various stages in pre-assembly of a powertrain assembly. [Figure 7D] 10A-10C illustrate various stages in pre-assembly of a powertrain assembly. [Figure 7E] 10A-10C illustrate various stages in pre-assembly of a powertrain assembly. [Figure 8A] 10 shows the power train assembly already assembled to the first housing part before the support shield is assembled. FIG. [Figure 8B] 10 shows the first housing portion with the powertrain assembly assembled and the support shield secured to the powertrain assembly. FIG. [Figure 9] 10 shows in perspective view a support member formed as a shoulder bolt for axial and radial positioning of the intermediate gear assembly and thus the intermediate gear of the power train assembly. FIG. [Figure 10] 10 is a cross-sectional view of the area of ​​the intermediate gear assembled with the shoulder bolt of FIG. 9, defining the axis of rotation of the intermediate gear; [Figure 11] 10 shows the first housing portion with the circuit board secured to the support of the powertrain carrier of the powertrain assembly after further steps in the assembly of the electronic assembly. FIG. [Figure 12] FIG. 10 is a view showing the first housing part without the pedal shaft assembly inserted therein. [Figure 13] FIG. 4 is a view of the second housing portion of the housing of the drive unit as seen from the inside. [Figure 14] 1 shows the second housing part being placed on the first housing part to close the housing space which contains, inter alia, the power train assembly, the electric motor drive and the electronic assembly. [Figure 15A] 10A-10C are views of the assembled housing from different sides. [Figure 15B] 10A and 10B are views of the assembled housing from different sides; [Figure 16A] FIG. 10 shows a power train assembly to which a rotor assembly is fixed, as an alternative assembly method. [Figure 16B] 1 illustrates a powertrain assembly including a rotor assembly with a support shield secured thereto prior to insertion into a first housing portion on which a stator is mounted. FIG. [Figure 17A]16B, showing the power train assembly with the rotor assembly secured and the support shield not yet secured, prior to insertion into the first housing portion. FIG. [Figure 17B] 17B shows the power train assembly already assembled to the first housing part according to FIG. 17A, with the support shield not yet assembled. [Figure 18] FIG. 1 is a perspective view showing a portion of a stepped gear assembly of a power train assembly having a stepped gear and a stepped pinion, showing that the carrier structure of the stepped gear is formed by a carrier portion extending in a spoke-like manner, unlike in the previous figure. [Figure 19] FIG. 19 is an exploded view of the stepped gear and stepped pinion of FIG. 18 with first and second bearings for the rotating assembly. [Figure 20] FIG. 10 is a single view showing the transmission members of the drive unit meshing with each other. [Figure 21] 10A and 10B are diagrams showing another modified example of a stepped gear in which the carrier structure is formed in a different shape. DETAILED DESCRIPTION OF THE INVENTION

[0034] 1A and 1B show the first housing part G1 of the proposed embodiment of the drive unit A from different perspectives. The first housing part G1 is formed as a housing half and, together with the second housing half, defines a housing space for accommodating the electronic and mechanical components of the drive unit. For connection to the second housing part G2 (in this example, the second housing half), the first housing part G1 includes a plurality of (at least two, in this example, three) fixing positions B1, B2, B3 distributed around its periphery. Furthermore, the first housing part G1 is formed with a housing opening OT1 for the pedal shaft T of the drive unit A and a support opening R for the rotor shaft RW of the electric motor drive part of the drive unit A.

[0035] As can be seen particularly from the view into the interior of the first housing part G1 shown in Figure 1B, the first housing part G1 forms a motor support position with a support pot for arranging the stator S of the electric motor drive. In Figure 1B, the stator S has already been inserted into the first housing part G1 during assembly of the drive unit A.

[0036] In the next assembly step, the rotor assembly R is inserted into the stator S and thus into the first housing part G1, as shown in Figure 2. The rotor assembly consists of a rotor unit with sheet-coated magnets and a rotor shaft RW. A motor pinion RR is formed on the rotor shaft RW or fixed in a rotationally fixed manner, so that the driving torque generated by the electric motor drive parts R, S is transmitted via the pinion RR.

[0037] After the rotor assembly R is inserted into the first housing portion G1, as shown in FIG. 3, the rotor shaft RW with the pinion R protrudes in the axial direction, allowing the stepped gear 31 of the power transmission mechanism assembly 1 to mesh with the pinion RR.

[0038] In the illustrated embodiment, the powertrain assembly 1 with a two-speed transmission is pre-assembled on the powertrain carrier 10, and the pre-assembled powertrain assembly 1 is then assembled and fixed to the first housing part G1. The support shield 2 is then attached to the powertrain carrier 10 of the powertrain assembly 1. This basic procedure is illustrated by the exploded view of Figure 4. Figure 5 shows the housing part G1 after the corresponding assembly steps have been completed, with the gear assembly 1 fixed to the housing part G1 and the support shield 2 fixed to the powertrain carrier 10 of the assembly 1.

[0039] Part of the power transmission mechanism assembly 1 is the intermediate gear 42, and when the drive unit is assembled, the driving torque generated by the electric motor is transmitted to the output gear 92 via the intermediate gear 42. A power transmission member 93 is connected to the output gear 92 in a rotationally fixed state, for example, and a belt wheel or a chain ring is connected to this power transmission member 93 in a rotationally fixed state, and torque is transmitted to the rear wheel of the electric bicycle via a transmission medium such as a belt or chain (see Figures 12, 14, 15A-15B, and 20).

[0040] The intermediate gear 42, here annular, is formed as part of the intermediate gear assembly 4. The intermediate gear 42 is rotationally fixedly connected to a hub 41, which can be connected to a bearing 40 for rotatably supporting the intermediate gear 42. Using a separate hub 41 can reduce the weight of the intermediate gear 42. For example, the intermediate gear 42 can be formed from high-strength steel, and the annular hub 41 can be formed from lightweight aluminum. When the hub 41 is pressed onto the annular intermediate gear 42, it is rotationally fixedly connected to the outer ring of the bearing 40. The pre-assembled intermediate gear assembly 4 is used in the process of pre-assembling the power train assembly 1.

[0041] According to FIG. 7A, when pre-assembling the power train assembly 1, the power train carrier 10 is first prepared. The power train carrier 10 forms a plurality of fixing positions 103a-103c, via which the power train carrier 10 and subsequently the pre-assembled power train assembly can be fixed in the first housing part G1 by means of screws, bolts or the like. The power train carrier 10 also has a support opening 100 with a support seat 1003. The support opening 100 is used to accommodate the stepped gear 31 that meshes with the pinion RR of the rotor assembly R. A further support position with a support dome 101 is formed on the power train carrier 10 at a position offset from the support opening 100. The intermediate gear assembly 4 is fixed to the support dome 101.

[0042] In a first assembly step of pre-assembling the power train assembly 1, before the intermediate gear assembly 4 is placed, the stepped gear assembly 3 is mounted in the support opening 100. In addition to the intermediate gear 31, the stepped gear assembly 3 is provided with a stepped pinion 32 connected in a rotationally fixed manner. To rotatably support the stepped gear 31 and the stepped pinion 32 on the power train carrier 10, a first bearing 35, here in the form of a roller bearing (see Figures 18 and 19), is provided, the outer ring of which is fixed to the support seat 1003. A support shaft 34, which connects the stepped gear 31 and the stepped pinion 32 in a rotationally fixed manner, is rotatably supported via the inner ring of this first bearing 35. Furthermore, a second bearing 33, for example in the form of a roller bearing, is provided at the end of the shaft remote from the support opening 100, thereby supporting the support shaft 34, and thus the stepped gear 31 and stepped pinion 32, on the transmission mechanism carrier 10 for rotation about the first rotation axis or transmission axis of the transmission mechanism assembly 1 defined by the support shaft 34.

[0043] 7B, in the pre-assembly process of the power train assembly 1, the stepped gear assembly 3 is first inserted into the power train carrier 10, and then the intermediate gear assembly 4 is placed thereon. As a result, the intermediate gear assembly 4 is guided laterally onto the stepped pinion 32 so that the intermediate gear 42 meshes with the stepped pinion 32. Then, the support opening of the bearing 40 of the intermediate gear assembly 4 is aligned with and centered within the support opening provided in the support dome 101.

[0044] After the intermediate gear assembly 4 has been inserted from the side, the intermediate gear 42 is fixed radially and axially to the power train carrier 10 via a support member in the form of a shoulder bolt 5. The shoulder bolt 5 has three successive sections 50, 51, 52 of different diameters. The first end 52 has the smallest diameter and is adapted to be pressed into an opening in the support dome 101. Along the longitudinal axis of the shoulder bolt 5, which is hollow in this case, a central section 51 follows, to which the inner ring of the bearing 41 of the intermediate gear assembly 4 is fixed. At the other axial end of the shoulder bolt 5, a second end 50, which has the largest diameter, follows the central section 51.

[0045] As can be seen particularly in the single-piece view of FIG. 9 and the cross-sectional view of FIG. 10 , the central portion 51 and the second end portion 50 each form a shoulder 511 or 501 with a (wavy) shoulder. When the shoulder bolt 5 is pushed in, the shoulder 511 of the central portion 51 faces the support dome 101, but the surfaces do not abut. Therefore, the length of the central portion 51 measured along the central axis of the shoulder bolt 5 is shorter than the width of the inner ring 401 of the bearing 40. This allows the shoulder 501 of the second end portion 50 to axially abut the inner ring 401 when the shoulder bolt 5 is pushed in, thereby axially fixing the inner ring 401 to the support dome 101. The intermediate gear assembly 4 is positioned axially and radially by inserting the shoulder bolt 5 into the intermediate gear 42 or the intermediate gear assembly 4 already positioned on the powertrain carrier 10 and forcing the first end 52 into the support opening of the support dome 101. The bearing 40 and its inner ring 401 function as a stopper for the shoulder bolt 5, and the central axis of the shoulder bolt 5 defines the rotation axis of the intermediate gear 42, and therefore defines the second transmission shaft of the power train assembly.

[0046] In the assembled state of the power transmission assembly 1 shown in FIG. 7E or 10 , the intermediate gear 42 (with hub 41) is fixed to the outer ring 402 of the bearing 40, and the inner ring 401 is fixed to the center portion 51 of the shoulder bolt 5. In this manner, the intermediate gear 42 can rotate about the central axis of the shoulder bolt 5 by the roller element 403 of the bearing 40 provided between the inner ring 401 and the outer ring 402. Therefore, the intermediate gear 42 is rotatably supported on the power transmission carrier 10 via the shoulder bolt 5, and can transmit torque from the stepped pinion 32 to the output gear 92 as part of the second transmission stage of the power transmission assembly 1.

[0047] Once the power train assembly 1 is fully pre-assembled, it is assembled into the first housing part G1 and secured in the first housing part G1 using fastening members (screws 6d and 6e in this case) according to the following assembly procedure shown in Fig. 8A. The support shield 2 is then positioned and secured to the power train assembly 1 thus inserted into the first housing part G1. The support shield 2 is aligned with the securing positions 102a, 102b, and 102c of the power train carrier 10 in the securing openings 202a, 202b, and 202c, and secured by, for example, the screws 6a, 6b, and 6c.

[0048] The support shield 2 is provided with a support position 203 for supporting the second bearing 33 of the stepped gear assembly 3. The support shield 2 also has a fitting opening 205 formed therein for the second end 50 of the stepped bolt 5, which protrudes axially from the intermediate gear 42. When the support shield 2 is assembled to the power train carrier 10 in a predetermined manner, the second bearing 33 is accommodated and supported in the support position 203, and the protruding portion of the second end 50 of the stepped bolt 5 passes through the fitting opening 205 in the support shield 2 and is accommodated in a form-fitting manner. The support shield 2 completely supports the stepped bolt 5 radially at its second end 50 over its entire circumference. Furthermore, because a portion of the second end 50 of the stepped bolt 5 protrudes axially from the support shield 2, the second end 50 can provide additional radial support in the second housing part G2, which is connected to the first housing part G1.

[0049] The second housing part G2 is assembled in a subsequent assembly step, in particular only after the electronic assembly 7 has been assembled to the first housing part G1 (after the support shield 2 has been fixed to the powertrain carrier 10 in FIG. 8B). In this case, the electronic assembly 7 includes at least two circuit boards 71 ​​and 72 connected to each other. One circuit board 72 is at least partially fixed to the support 107 of the powertrain carrier 10. The part of the powertrain carrier 10 assembled to the first housing part G1 therefore also serves to support and fix part of the electronic assembly 7, in this case part of the circuit board 72. In this example, the electronic assembly 7 is provided for electronically controlling the electric motor drives R, S of the drive unit A.

[0050] After assembling the electronic assembly 7 into the first housing part G1 as shown in FIG. 11, in one of the subsequent assembly steps shown in FIG. 12, a step is performed in which a pre-assembled pedal shaft assembly T including a drive gear wheel 92 and a pedal shaft is inserted into the first housing part G1.

[0051] During the assembly of the drive unit A, the second housing part G2 is assembled. If necessary, this assembly is performed after the completion of assembly steps such as attaching a seal to the outer periphery of the first housing part G1. The interior of the second housing part G2 is shown in FIG. 13. In addition to the housing opening OT2 for the pedal shaft of the pedal shaft assembly T described above, the second housing part G1 has a recess 82 on its interior side for the axially protruding portion of the support shield 2. This recess 82 accommodates the second bearing 33 of the stepped gear assembly 3 of the power transmission mechanism assembly 1. The interior of the second housing part G2 also has a receiving part 85 for the second end 50 of the shoulder bolt 5. When the housing G is closed, the part of the second end 50 of the shoulder bolt 5 protruding from the support shield 2 extends into this receiving part 85, so that the second end 50 is supported radially on the circumferential side within the second housing part G2 as well (without abutting against the interior of the second housing part G2 in the axial direction).

[0052] 14 shows the state in which the second housing part G2 is placed on the first housing part G1. In this case, the connection positions B4, B5, and B6 of the second housing part G2 align with the connection positions B1, B2, and B3 of the first housing part G1, so that the two housing parts G1 and G2 can be fixed to each other via the pairs of connection positions B1 / B4, B2 / B5, and B3 / B6. This seals the storage space of the housing G, which houses the power train assembly 1 and the motor drive parts R and S.

[0053] 15A and 15B show the assembled housing G of the drive unit A from two different sides. On the side of the first housing part G1, there is shown a plug connector part 710 formed by the electronic assembly 7 and extending from the inside to the outside of the housing G. The plug connector part 710 has one or more plug connectors for connecting the drive unit A to a power source and / or higher-level control electronics.

[0054] 16A, 16B, 17A and 17B show two ways of assembling the power train assembly 1 and the electric motor drives R and S.

[0055] 16A and 16B show a variant in which the powertrain assembly 1 is fully pre-assembled, whereby the powertrain assembly 1 is assembled into the first housing part G1 with the support shield 2 as well as other components already assembled on the powertrain carrier 10. The rotor assembly R is also already arranged on the pre-assembled powertrain assembly, in particular on the powertrain carrier 10, so that the pinion RR of the rotor shaft RW is in mesh with the intermediate gear 31 of the powertrain assembly 1 before the powertrain assembly 1 is placed in the first housing part 1. The powertrain assembly 1 with the rotor assembly R already arranged thereon (the rotor unit protruding below the powertrain carrier 10) is then assembled into the first housing part G1 in which only the stator S is arranged in the motor support position.

[0056] 17A and 17B, the rotor assembly R is also pre-assembled with the powertrain assembly 1 before being inserted into the first housing part G1. In contrast to the embodiment shown in Figures 16A and 16B, the support shield 2 is attached to the powertrain carrier 10 after the powertrain assembly 1 with the rotor assembly R has been inserted into the first housing part G1.

[0057] 18 and 19 show enlarged details of another configuration example of the stepped gear assembly 3. In the variant of Figures 18 and 19, the power train carrier 10 is designed with a protruding flange 11. The protruding flange 11 is arranged at a support position of the gear carrier 10 and protrudes beyond the gear carrier 10.

[0058] FIGS. 18 and 19 show enlarged details of another design example of the stepped gear assembly 3. In the variants of FIGS. 18 and 19, the design of the stepped gear 31 differs from that of FIGS. 4 to 7E. The stepped gear 31 of FIGS. 18 and 19 includes an externally toothed ring gear 312. The ring gear 312 is connected to the hub 310 of the stepped gear 31 via a carrier structure 311. The carrier structure 311 is formed by a plurality of radially extending spoke-like carrier portions 3111, and the stepped gear 31 is relatively lightweight. Relatively large through-openings 3110 are formed between the spoke-like carrier portions 3111. These serve to reduce airborne noise when the stepped gear 31 is rotating.

[0059] The stepped gear 31 is rotationally fixedly secured via a hub 310 of the stepped gear 31 to a first axial end of a support shaft 34 forming the stepped pinion 32. A first bearing 35 is arranged on the outer periphery of the hub 310 and is inserted into a support seat 1003 in a support opening 100 of the power train carrier 10. A second bearing 33 is fixed to the opposite axial end of the support shaft 34, which is radially supported within the support shield 2.

[0060] Figure 20 is a diagram of the interacting gears of the drive unit A. Figure 20 particularly shows how the pinion RR of the rotor shaft RW meshes with the stepped gear 31. Through this first transmission stage of the powertrain assembly 1, torque is transmitted from the stepped pinion 32 to an intermediate gear 42. The intermediate gear 42 not only meshes with the stepped pinion 32, but also with the output gear 92 of the pedal shaft assembly T, transmitting the driving torque generated by the motor to the rear wheel of the electric bicycle.

[0061] The stepped gear 31 shown in FIG. 20 has the same design as the stepped gear 31 shown in FIGS. 4 to 7E. FIG. 21 is an enlarged, isolated view of the stepped gear, showing a different design for the carrier structure 311. In the variation shown in FIG. 21, instead of circular through-openings 3110 arranged continuously along a circumferential line, through-openings 3110 with a different contour are selected, which also affects the contour of the carrier portion 3111 extending radially from the hub 310 to the ring gear 312. Therefore, in the variation shown in FIG. 21, in the contour shape of each through-opening 3110, opening edges 3110a and 3110b that are opposed to each other in the circumferential direction extend from the hub 310 toward the ring gear 312 in the opposite direction to the rotation direction D of the stepped gear 31. In the illustrated configuration, the opposing opening edges 3110a and 3110b of the contour of the through-opening 3110 are each formed in an arrow-like or curved shape at the center in the direction opposite to the rotation direction D. The corresponding design of the through openings 3110 and the resulting radial spoke-like support portions 3111 not only contributes to reducing the weight of the stepped gear 31, but also allows for further optimization of the airborne sound level generated during operation of the drive unit A. [Explanation of symbols]

[0062] 1 Powertrain Assembly 10 Powertrain carrier 100 Support opening 1003 Support sheet 101 Support Dome 102a~102c Fixed position 103a~103c Fixed position 107 Support part 2 Support Shield 202a~202c Fixing opening 203 Support position 205 Mating opening Three-stage gear assembly 31 Stepped gear 310 Hub 311 Career Structure 3110 Through opening 3110a, 3110b Opening edge 3111 Carrier Section 312 Ring gear 32 stepped pinion 33 (roller) bearing 34 Bearing shaft 35 (roller) bearing 4 Intermediate gear assembly 40 (roller) bearing 401 Inner Circle 402 outer ring 403 Roller body 41 Hub 42 Intermediate gear 5 Step bolt (support member) 50 Second end 501 Shoulder 51 Central part 511 Shoulder 52 First end 6a~6e Screws (fastening members) 7 Electronic Assembly 71, 72 Circuit board 710 Plug connector part 82 recess 85 Receiving part 92 Output gear 93 Power transmission components A Drive Unit B1~B6 connection position D Rotation direction G Housing G1, G2 housing half (housing part) M Center axis / Rotation axis OR Rotor shaft support opening OT1, OT2 Pedal axle housing opening R rotor assembly RR (motor) pinion RW rotor shaft S stator T Pedal shaft (assembly)

Claims

1. at least one electric motor drive (R, S); a pedal shaft assembly (T); a power transmission assembly (1) that transmits the driving torque generated by the electric motor drive unit (R, S) to the output member (92) of the pedal shaft assembly (T), The power train assembly (1) comprises a power train carrier (10) rotatably supporting at least two interacting transmission members (32, 42), respectively; a first end (52) of the support member (5) being rotationally fixedly fitted to a part (101) of the power transmission carrier (10), a second end (50) of the support member (5) defining an axial position of the one transmission member (42) on the power transmission carrier (10) relative to the rotation axis (M), and the support member (5) having a central portion (51) between the first end (52) and the second end (50) for rotatably supporting the one transmission member (42).

2. 2. A drive unit according to claim 1, characterized in that the first end (52) of the support member (5) is press-fit into an opening formed in the part (101) of the power train carrier.

3. 3. The drive unit according to claim 1, wherein a shoulder (501) is formed at the second end (50), and the axial position of the rotatably supported transmission member (42) is determined via the shoulder (501).

4. 4. A drive unit according to claim 1, wherein the one transmission member (42) is rotatably supported at the central portion (51) of the support member (5) via a bearing (40), and an inner ring (401) of the bearing (40) is connected to the central portion (51) in a rotationally fixed manner.

5. A drive unit according to claims 3 and 4, characterized in that the shoulder (501) of the second end (50) abuts axially against the inner ring (401) of the bearing (40).

6. 6. A drive unit according to claim 5, characterized in that the axial length of the central part (51) is shorter than the axial length of the inner ring (401).

7. The one transmission member rotatably supported via the support member (5) is constituted by an annular gear (42), 7. A drive unit according to any one of claims 4 to 6, characterized in that the annular gear (42) is rotationally fixedly connected to a hub (41), the hub (41) being fixed to an outer ring (402) of a bearing (4), the outer ring (402) being rotatable relative to the inner ring (401).

8. 8. A drive unit according to claim 7, characterized in that the annular gear (42) is made of high strength steel and the hub (41) is made of aluminium.

9. The first end (52), the central portion (51) and the second end (50) are formed with different diameters on the support member (5); 9. A drive unit according to claim 1, wherein the diameter of the second end (50) is greater than the diameter of the central portion (51), which in turn is greater than the diameter of the first end (52).

10. 10. A drive unit according to any one of claims 1 to 9, characterized in that a support shield (2) is fixed to the power train assembly (1), and the second end (50) is received in the support shield (2) in a form-fitting manner.

11. 11. The drive unit according to claim 10, wherein the second end (50) is form-fittingly received in a support opening (205) of the support shield (2), and the second end (50) protrudes through the support opening (205).

12. 12. A drive unit according to claim 11, characterized in that the part of the second end (50) that protrudes through the support opening (205) is received in a receiving part (85) provided in a part (G2) of a housing (G) of the drive unit (A), the part (G2) of the housing (G) receiving the electric motor drive part (R, S) and the power train assembly (1) provided with the support shield (2).

13. 13. A drive unit as described in claim 12, characterized in that the part of the second end (50) protruding from the support opening (205) is supported in the receiving part (85) radially relative to the rotation axis (M) defined by the support member (5).

14. a stepped gear (31) rotatably supported on the power train carrier (10), meshing with a pinion (RR) of a rotor shaft (RW) of a rotor assembly (R) of the electric motor drive unit (R, S), and rotationally fixedly coupled to a stepped pinion (32) which is a first transmission member of the power train assembly (1); 14. A drive unit according to any one of claims 1 to 13, characterized in that the stepped pinion (32) meshes with an intermediate gear (42), which is the second transmission member of the power train assembly (1), rotatably supported on the power train carrier (10) via the support member (5).

15. 15. A drive unit as claimed in claim 14, characterized in that said intermediate gear (42) meshes with an output gear (92) of said pedal shaft assembly (T).

16. 16. A drive unit according to claim 14 or 15, characterized in that the stepped gear (31) and the stepped pinion (32) are rotationally fixedly connected to a support shaft (34), the support shaft (34) being rotatably supported via a bearing (35) accommodated in the transmission mechanism carrier (10).

17. The stepped gear (31) has an externally toothed ring gear (312) and a hub (310), 17. A drive unit according to any one of claims 14 to 16, characterized in that the ring gear (312) is connected to the hub (310) of the stepped gear (31) via a carrier structure (311) having a plurality of through openings (3110).

18. 18. A drive unit according to claim 17, characterized in that the carrier structure (311) is constituted by a plurality of carrier parts (3111) extending in the form of spokes from the hub (310) to the ring gear (312).

19. 18. A drive unit as described in claim 17, characterized in that the plurality of through openings (3110) are arranged consecutively in the carrier structure (310) in a row along the circumferential direction around the rotation axis of the stepped gear (31).

20. 20. The drive unit of claim 19, wherein the rotation direction (D) of the stepped gear (31) is specified during operation of the drive unit (A) so that the drive torque generated by the electric motor drive section (R, S) is transmitted in the direction of the output member (92) of the pedal shaft assembly (T), and the contours of each through opening (3110) have opening edges (3110a, 3110b) that face each other circumferentially and extend from the hub (310) toward the ring gear (312) extend in the opposite direction to the rotation direction (D) and are formed in a curved or arrow-like shape.

21. 21. A drive unit according to any one of claims 10 to 13 and any one of claims 14 to 20, characterized in that the stepped gear (31) and the stepped pinion (32) are rotationally fixedly connected to a support shaft (34), and the support shaft (34) is rotatably supported via a bearing (33) accommodated in the support shield (2).

22. 22. A drive unit according to any one of the preceding claims, characterized in that the support element is formed as a shoulder bolt (5).

23. 23. A drive unit according to any one of claims 1 to 22, characterized in that the power train carrier (10) comprises a support (107) to which at least a part of the electronic assembly (7) of the drive unit (A) is fixed.

24. at least one electric motor drive (R, S); a pedal shaft assembly (T); a power transmission assembly (1) that transmits the driving torque generated by the electric motor drive section (R, S) to the output member (92) of the pedal shaft assembly (T), The power train assembly (1) comprises a power train carrier (10) that rotatably supports at least two interacting transmission members (32, 42), the electric motor drive (R, S) and the power train assembly (1) are accommodated in a housing (G) of the drive unit (A), and the pedal shaft assembly is rotatably supported on the housing (G); the power train assembly (1) is pre-assembled as a structural unit with at least two transmission members (32, 42) interacting with each other, already rotatably supported on the power train carrier (10); 10. A method according to claim 9, characterized in that the pre-assembled structural unit is assembled into a housing part (G1) of the housing (G) which already contains at least the stator (S) of the electric motor drive part (R, S).

25. a stepped gear (31), a stepped pinion (32) which is a first transmission member of the power train assembly (1) and which is rotationally fixedly coupled to the stepped gear (31), and an intermediate gear (42) which is a second transmission member of the power train assembly (1) and which meshes with the stepped pinion (31), are pre-assembled in a state in which they are rotatably supported on the power train carrier (10) of the power train assembly (1); 25. A method according to claim 24, characterized in that the stepped gear is arranged to mesh with a pinion (RR) of a rotor shaft (RW) of the electric motor drive (R, S).

26. 26. The method according to claim 24 or 25, characterized in that one of the transmission members (32, 42) is rotatably supported on the power train carrier (10) around the rotation axis (M) via a support member (5), a first end (52) of the support member (5) is rotationally fixedly fitted to a part (101) of the power train carrier (10), a second end (50) of the support member (5) defines the axial position of the one transmission member (42) on the power train carrier (10) relative to the rotation axis (M), and the support member (5) comprises a central portion (51) between the first end (52) and the second end (50) for rotatably supporting the one transmission member (42).

27. 27. The method according to claim 26, characterized in that the support member (5) is assembled to the one transmission member (42) already arranged on the power train carrier (10) so that the first end (52) of the support member (5) is guided through the transmission member (42) and inserted into the part (101) of the power train carrier.

28. 28. A method as claimed in claims 25 and 27, characterized in that the support member (5) is fitted onto the intermediate gear (42) already placed on the power train carrier (10) and meshing with the stepped pinion (32).

29. Before the pre-assembled power train assembly (1) is assembled into the housing part (G1), a rotor assembly (R) having a rotor shaft (RW) with a pinion (RR) that meshes with the stepped gear (31) of the power train assembly (1) is assembled into the housing part (G1) that already includes the stator (S) of the electric motor drive part (R, S).

29. A method according to any one of claims 24 to 28, characterized in that

30. 29. A method according to any one of claims 24 to 28, characterized in that a rotor assembly (R) comprising a rotor shaft (RW) having a pinion (RR) meshing with a stepped gear (31) of the power train assembly (1) is assembled to the power train assembly (1), and the power train assembly (1) pre-assembled with the rotor assembly (R) is assembled to the housing part (G1) already comprising the stator (S) of the electric motor drive part (R, S).

31. a support shield (2) is assembled to the power train carrier (10) before the power train assembly (1) is assembled to the housing part (G1) already comprising the stator (S) of the electric motor drive part (R, S), or 31. A method according to any one of claims 24 to 30, characterized in that a support shield (2) is assembled to the power train carrier (10) after the power train assembly (1) has been assembled to the housing part (G1) already comprising the stator (S) of the electric motor drive part (R, S).

32. 32. A method according to any one of claims 24 to 31, characterized in that at least a part of the electronic assembly (7) of the drive unit (A) is fixed to a support (107) of the power train carrier (10).

33. 33. The method according to any one of claims 25 to 32, characterized in that the pedal shaft assembly (T) is assembled to the housing part (G1) after the power train assembly (1) has been assembled to the housing part (G1) and before the housing space of the housing (G) in which the electric motor drive part (R, S) and the power train assembly (1) are accommodated is closed by another housing part (G2) of the housing (G).

34. An electric bicycle comprising a drive unit according to any one of claims 1 to 23.

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