Circuit board assembly for electric bicycle drive unit and assembly method

Abstract

The proposed solution particularly relates to a circuit board assembly (7) for a drive unit (A) of an electric bicycle. The circuit board assembly includes two interconnected circuit boards (71, 72) and a circuit board holder (74), one of which is fixed to the circuit board holder (74) and which holds the circuit boards (71, 72) at a distance determined by the circuit board holder (74).

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, including at least one electric motor drive unit. The at least one electric motor drive unit is used to provide a drive torque generated by an 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 the external force is typically applied in addition to a drive torque generated by muscle force applied to a 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] The electric motor drive of the drive unit is usually provided with at least one electric motor with a stator and a rotor. The stator is accommodated in a housing part of the drive unit and supported so that it is rotationally fixed. For this purpose, the housing part forms a support position, for example in the form of a support pot, into which the stator (possibly together with a pre-assembled rotor) is placed during assembly of the drive unit.

[0005] The drive unit housing, which houses the electric motor drive in particular, typically also houses electronic components, such as one or more circuit boards. The electronic components, for example, serve to supply current to the electric motor drive and to house sensors and circuit components for controlling the drive unit. When multiple circuit boards are housed in the drive unit housing, it is often difficult to position and hold these circuit boards in place while additional components are being installed in the drive unit housing. Therefore, when multiple circuit boards are housed in a single housing, stable assembly of the drive unit can be very difficult. Summary of the Invention [Problem to be solved by the invention]

[0006] In light of this, there is an increasing demand for improved means for arranging multiple circuit boards in the housing of a drive unit, particularly a drive unit for an electric bicycle.

[0007] The proposed solution provides, inter alia, a circuit board assembly having two interconnected circuit boards, at least one of which is fixed to a circuit board holder, which holds the circuit boards at a predetermined distance from each other. The two circuit boards are arranged at a predetermined distance via the circuit board holder so that they support each other and prevent tilting relative to each other. Therefore, the circuit board assembly with the pre-assembled circuit board holder can be installed in the housing of the drive unit in a process-reliable manner, since the relative positions of the two circuit boards are already ensured by the circuit board holder.

[0008] For example, the circuit board holder has at least one spacer member that determines the distance at which two circuit boards are held together. Corresponding spacer members are arranged, for example, above one circuit board and below the other circuit board. Therefore, in this embodiment, the spacer member is arranged between the two circuit boards, ensuring the distance between the circuit boards arranged above and below, and providing a structure in which the circuit boards support each other.

[0009] For example, at least one of the circuit boards can be form-fitted to at least one spacer member. For example, form-fitting connections between the circuit boards and the circuit board holders can facilitate pre-assembly of the circuit board assembly and / or relatively easily ensure a specific orientation of each circuit board relative to the circuit board holder. This form-fitting may particularly include a configuration in which a member of each circuit board and a spacer member of the circuit board holder contact each other form-fittingly without the use of additional fasteners. For example, form-fitting members of the circuit boards may be inserted into the spacer members to form-fit connection between at least one of the circuit boards and the at least one spacer member. The form-fitting members may be, for example, members integrally formed with the respective circuit boards. In one embodiment, for example, form-fitting members of the circuit boards, particularly form-fitting members formed on the respective circuit boards, are inserted into openings in the spacer members.

[0010] Alternatively or additionally, at least one spacer element of the circuit board holder may be formed with a through-opening, e.g., a through-hole. The through-opening provides a passage for a fastening member (of the circuit board assembly) to secure the circuit board assembly to the carrier component. Thus, the spacer element of the circuit board holder not only supports and keeps the two circuit boards spaced apart, but also serves to secure the circuit board assembly, consisting of the two circuit boards and the circuit board holder, to the carrier component. To secure the circuit board assembly to the carrier component, fastening members such as screws or bolts (as part of the circuit board assembly) are provided, which pass through the through-openings in the spacer element. This allows a pre-assembled circuit board assembly with two circuit boards and a circuit board holder to be fastened to a carrier component of the drive unit using the spacer element of the circuit board holder. This carrier component may be formed, for example, by a housing part of the drive unit or by components of the drive unit already attached to the housing component.

[0011] In one embodiment, at least one spacer member of the circuit board holder is sleeve-shaped.

[0012] Basically, the circuit board holder can include multiple (at least two) spacer members connected to each other via the connecting structure of the circuit board holder. The two circuit boards can support each other at multiple positions via the multiple spacer members of the circuit board holder, thereby increasing the rigidity of the circuit board assembly. Furthermore, the multiple spacer members, each of which contacts both circuit boards, make it easier to set the orientation of the two circuit boards relative to each other and the circuit board holder. In particular, by combining multiple form-fitting members provided on the circuit boards that connect (particularly, fit) to the multiple spacer members, the two circuit boards can be connected to the circuit board holder only in unique orientations relative to each other.

[0013] In one embodiment, the two circuit boards are not only physically connected to each other via the circuit board holder, but also electrically connected to each other via a connecting member. Therefore, an electrical signal can be transmitted between the two circuit boards via at least one connecting member. The connecting member can be formed, for example, by at least one connecting plug. By providing the connecting plug on one of the circuit boards, the other circuit board can be plugged into the connecting plug during assembly of the circuit board assembly to establish an electrical connection.

[0014] In one embodiment, a connecting member provided for electrical connection can be configured to pass through the circuit board holder. Thus, the connecting member between two circuit boards is provided in the area of ​​the circuit board assembly where the circuit board holder is disposed between the two circuit boards. For example, the circuit board holder can have an opening that receives at least a portion of the connecting member in a form-fitting manner.

[0015] In an embodiment in which a connecting member provided for electrically connecting two circuit boards fits into an opening in the circuit board holder, the connecting member can be optionally used to ensure that the two circuit boards can only be assembled in a specific orientation relative to the circuit board holder and to each other. The opening into which at least a portion of the connecting member fits in a form-fitting manner can function as a positioning opening because the connecting member can only pass in a specific orientation. Thus, a circuit board holder having an opening can only be attached in a specific orientation to a circuit board that already has a connecting member. After the circuit board holder is attached to this circuit board, another circuit board is attached to the circuit board holder and connected to the connecting member, electrically coupling the circuit boards. In this case, the other circuit board can only be connected to the (possibly rigid) connecting member via corresponding contacts and / or connection sleeves on the other circuit board in a specific orientation, so that the additional circuit board can also only be assembled in a specific orientation relative to the circuit board holder.

[0016] The openings for the connecting members can be formed on the circuit board holder, for example in the above-mentioned connecting structure, through which the spacer members of the circuit board holder are connected to one another.

[0017] Part of the proposed solution is also a drive unit for an electric bicycle, comprising an electric motor drive and an embodiment of the proposed circuit board assembly.

[0018] The plug connector portion may comprise one or more plug connectors for connecting the drive unit to a power source and / or higher level control electronics onboard the e-bicycle and may be provided on one of the circuit boards of the circuit board assembly. Alternatively or additionally, at least part of the sensor technology capable of measuring torque (e.g., on the pedal axle of the drive unit) and / or an inertial measurement unit may be provided on at least one of the circuit boards.

[0019] In one embodiment, the electric motor drive of the drive unit comprises a rotor rotatable about a rotor axis and a power train assembly whose transmission member is coupled to the rotor of the electric motor drive. To compactly arrange the circuit board assembly in the housing of such a drive unit, for example, the circuit board assembly may be fixed to a power train carrier on which the transmission member of the power train assembly is at least partially, in particular rotatably, supported. The power train carrier in such a drive unit thus serves to support the transmission member and the circuit board assembly.

[0020] To facilitate assembly of the circuit board assembly, at least one spacer member of the circuit board holder may be provided with through openings through which fasteners pass to secure the circuit board assembly to the powertrain carrier, such that the circuit board assembly can be secured to the powertrain carrier of the drive unit during assembly using the fasteners passing through the spacer member.

[0021] The proposed solution also includes a method for assembling a circuit board assembly in a housing part of a drive unit of an electric bicycle, in which a circuit board assembly including two circuit boards and a circuit board holder is pre-assembled so that the two circuit boards are fixed to the circuit board holder and the circuit boards are held at a predetermined distance, and then assembled in the housing part of the drive unit.

[0022] In this way, the two circuit boards and the circuit board holder (and other components, if necessary) can form a pre-assembled unit in which the two circuit boards are positioned so as to be supported by the circuit board holder in a predetermined orientation relative to each other, and then assembled into the housing of the drive unit.

[0023] In particular, embodiments of the proposed circuit board assembly can be used with the proposed assembly method, and therefore, the features and advantages described above and below for embodiments of the proposed circuit board assembly also apply to embodiments of the proposed assembly method, and vice versa.

[0024] For example, in embodiments of the proposed assembly method, the drive unit may comprise an electric motor drive with a rotor rotatable about a rotor axis, and a powertrain assembly having a transmission member coupled to the rotor and at least partially assembled to a powertrain carrier of the powertrain assembly. The powertrain carrier may be assembled to the housing portion before the pre-assembled circuit board assembly, so that the pre-assembled circuit board assembly is secured to the powertrain carrier during assembly of the drive unit. [Brief explanation of the drawings]

[0025] The accompanying drawings show examples of possible implementations of the proposed solution. [Figure 1A] 1A-1C are perspective views of an embodiment of the proposed drive unit, shown in different longitudinal side views; [Figure 1B]1A-1C are perspective views of an embodiment of the proposed drive unit, shown in different longitudinal side views; [Figure 2A] 1C is a view of a first housing part of the housing of the drive unit shown in FIGS. 1A and 1B, as seen from the outside. FIG. [Figure 2B] 2B is a view showing the inside of the first housing part of FIG. 2A. FIG. [Figure 3] FIG. 4 is a view showing a first housing part to which a stator of an electric motor drive part of a drive unit is assembled. [Figure 4] 10 is a view showing a stage in the assembly process where a rotor is assembled to a first housing portion to which a stator has already been assembled. FIG. [Figure 5] FIG. 2 is a view showing a first housing part to which a stator and a rotor are assembled. [Figure 6] 1 shows the stage where the power train assembly and support shield are assembled to the first housing part which already contains the stator and rotor. FIG. [Figure 7] 10 shows a first housing portion to which the powertrain assembly is secured and a support shield secured to the powertrain assembly. FIG. [Figure 8] FIG. 1 shows a first housing part onto which a pre-assembled circuit board assembly is mounted according to the proposed solution. [Figure 9] 1 illustrates a first housing portion having a circuit board assembly mounted thereon and at least partially secured to a powertrain carrier of a powertrain assembly. [Figure 10] 1 is an exploded view of a circuit board assembly including a first circuit board, a circuit board holder, and a second circuit board. [Figure 11] FIG. 10 is a perspective view showing a circuit board holder of another embodiment of a circuit board assembly. [Figure 12] 12 is a diagram showing the circuit board assembly with the circuit board holder of FIG. 11 assembled and fixed to the power train carrier. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0026] 1A and 1B are perspective views of a drive unit A of an electric bicycle, viewed from two different sides. The drive unit A has a housing G that houses electronic and mechanical components. The housing G consists of a first housing portion G1 and a second housing portion G2 that are connected to each other, each of which forms a housing half.

[0027] Both ends of the pedal shaft T protrude from the housing G. After attaching pedals to both ends and properly assembling the drive unit A to the electric bicycle, the electric bicycle can be driven by applying a driving torque to the pedal shaft T through muscle operation. In particular, torque generated through muscle operation via the power transmission member K of the pedal shaft T can be output using a belt wheel or chain ring connected to the power transmission member K in a rotationally fixed state, and can be transmitted to the rear wheel of the electric bicycle via a transmission medium such as a belt or chain. In addition, torque generated by external force operation can be applied to the power transmission member K. The torque is supplied by an electric motor drive unit housed in the housing G and transmitted to the power transmission member K via a transmission mechanism also housed in the housing G.

[0028] On the side formed by the first housing part G1, the plug connector part ST of the circuit board assembly 7 is visible, having been pulled out from the inside of the housing G. The plug connector part ST protrudes to the outside through a plug opening O7 and has one or more plug connectors for connecting the drive unit A to a power source and / or higher-level control electronics installed in the electric bicycle.

[0029] 2A and 2B 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 part G2, defines a housing space for accommodating the electronic and mechanical components of the drive unit A. For connection to the second housing part G2 (the second housing half in this example), 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. The first housing part G1 also includes a housing opening OT for the pedal shaft T of the drive unit A and a support opening OR for the rotor shaft 30 of the electric motor drive part of the drive unit A. The rotor shaft 30 is part of the rotor 3, which is rotatable about a rotor axis that coincides with the axis of the rotor shaft 30, and applies a driving torque generated by external force to the stator 2 of the electric motor drive part (see in particular FIGS. 4 to 7).

[0030] As is particularly evident from the view into the interior of the first housing part G1 shown in Figure 2B, the first housing part G1 forms a (motor) support position 1 with a support pot, which is intended in particular for the arrangement of a stator 2 of the electric motor drive.

[0031] The pot-shaped support position 1, i.e., the support position provided by forming a support pot in the first housing part G1, has an inner wall 11 that extends completely circumferentially around the support opening OR of the rotor shaft 30 (and thus around the rotor axis of the rotor 3 defined by the rotor shaft 30). The inner wall 11 extends perpendicular to the bottom 10 of the support position 1 and is exemplarily formed in this case by a flower-like rib structure centered on the support opening OR.

[0032] In Figure 3, the stator 2, which is made up of multiple coils 23, is inserted into the first housing part G1 and fixed in place during assembly of the drive unit A. In a subsequent assembly process, as shown in Figure 4, the rotor 3, which is made up of multiple parts, is inserted into the stator 2 and the first housing part G1. The rotor 3 is made up of a rotor unit with a magnet covered with a sheet and a rotor shaft 30. A (motor) pinion 31 is formed or fixed in a rotationally fixed state on the rotor shaft 30, so that the drive torque generated by the electric motor drives 2 and 3 is transmitted via the pinion 31.

[0033] When the drive unit A is assembled as specified, a driving torque generated by an external operation is transmitted from the pinion 31 to a transmission mechanism connected to the power transmission member K. In this case, at least a part of this transmission mechanism is provided by a pre-assembled transmission mechanism assembly 4. As shown in FIG. 5, after the stator 2 and the rotor 3 are arranged at the support position 1 as specified, the transmission mechanism assembly 4 is assembled into the first housing part G1.

[0034] In this example, a number of meshing gears are rotatably supported on the transmission carrier 40 of the transmission assembly 4. The gears are particularly intended to mesh with the pinion 31 when the transmission assembly 4 is mounted in the first housing part G1 in a defined state. The gears of the transmission can be pre-mounted on the transmission carrier 40.

[0035] After the power train assembly 4 has been assembled in advance, it is attached to the first housing part G1 according to the procedure shown in Fig. 6 and fixed inside the first housing part G1 with fastening members such as screws and bolts. Then, the support part shield 5 is placed on the power train assembly 4 inserted into the first housing part G1 as described above and fixed thereto.

[0036] After further mechanical and electronic components are attached to the first housing portion G1, the second housing portion G2 is attached and fixed to the first housing portion G1, thereby sealing the accommodation space of the housing G that accommodates the power train assembly 4 and the motor drivers 2 and 3.

[0037] As shown in particular in Figures 8 to 10, before the housing space is closed, the components already attached to the first housing part G1 include a circuit board assembly 7 with a plug connector part 73.

[0038] The circuit board assembly 7 comprises a first (main) circuit board and a second (additional) circuit board, with a circuit board holder 74 disposed therebetween, allowing the two circuit boards 71, 72 to support each other and be positioned at a predetermined distance via the circuit board holder 74 (see FIG. 8). The first circuit board 71 is equipped with at least one torque sensor and a plug connector unit 73. The second circuit board 72 has a smaller area than the first circuit board 71, but is equipped with, for example, a rotor attitude sensor and / or an inertial measurement unit. In this example, the two circuit boards 71, 72 serve to supply current to the electric motor drive units 2, 3 and electronically control the drive units.

[0039] In this case, the circuit board assembly 7 pre-assembled with the circuit board holder 74 is installed in the first housing part G1, with the power train assembly 4 already attached to it. The power train carrier 40, which is already arranged in the first housing part G1, forms the support 407 on which the circuit board assembly 7 is fixed. For this purpose, the first large circuit board 71 is fixed to the support 407 at several connection locations, which are defined by holes (407.1, 407.2, 407.3) provided in the power train carrier 40. In this example, parts of the first circuit board 71 are also fixed directly to the first housing part G1, using the connection locations formed by the first housing part G1 for this purpose.

[0040] When the circuit board assembly 7 is placed in a predetermined state on the transmission mechanism carrier 40, the plug connector portion 73 is inserted into the plug opening O7 on the housing side, and when the circuit board assembly 7 is placed and fixed in the first housing portion G1, the plug connector portion 73 protrudes outward from the inside of the first housing portion G1.

[0041] The circuit board assembly 7 is fixed to the circuit board holder 74 by means of the power train carrier 40, which acts as a carrier part. The circuit board holder 74 comprises a number of spacer elements (three in this case) in the form of spacer sleeves 741, 742, 743. As shown in Figure 9, the spacer sleeves 741, 742, 743 determine the spacing between the two circuit boards 71, 72 and each have a through opening through which fastening elements in the form of fixing screws 6.1, 6.2, 6.3 pass to fix the circuit board assembly 7 in the holes 407.1, 407.2, 407.3 in the support part 407 on the power train carrier.

[0042] As is clear from the exploded view of Figure 10, both the first large circuit board 71 and the second smaller (additional) circuit board 72 include a plurality of form-fitting elements, through which the circuit boards 71, 72 can be connected to the circuit board holder 74 by form-fitting before fastening screws 6.1, 6.2, 6.3 are attached. The form-fitting elements are formed as protruding insert sleeves 7131, 7132, 7133 on the upper side of the first circuit board 71. The underside of the second circuit board 72, facing the first circuit board 71, is also provided with form-fitting elements in the form of protruding insert sleeves, two of which (7231 and 7232) are shown in the exploded view of Figure 10. Alternatively, holes may simply be drilled in the circuit board 71 at the positions of the insert sleeves 7131, 7132, 7133.

[0043] The insertion sleeves 7131, 7132, 7133, 7231, and 7232 are inserted into the end openings of the corresponding spacer sleeves 741, 742, and 743 of the circuit board holder 74, respectively. In the drawing, the first and second circuit boards 71 ​​and 72 are connected to each other in a predetermined position and to the circuit board holder 74 in a predetermined orientation without using tools via the three spacer sleeves 741, 742, and 743 connected by the triangular connecting structure 740. By fitting together, the first and second circuit boards 71 ​​and 72 and the circuit board holder 74 can be installed in the first housing part G1 as a pre-assembled unit.

[0044] For example, the circuit board holder 74 may be inserted first onto the top of the first circuit board 71. Then, the second circuit board 72 is inserted into the circuit board holder 74. It is of course also possible to insert the circuit board holder 74 into the smaller second circuit board 72 first, and then insert the circuit board holder 74 with the second circuit board 72 into the first circuit board 71. In either case, connecting the two circuit boards 71, 72 to the circuit board holder 74 involves a connecting member in the form of a connecting plug 712 that electrically couples the two circuit boards 72, 71, 72 to each other. In the illustrated embodiment, the connecting plug 712 is part of the first circuit board 71, and the second circuit board 72 is inserted into the connecting plug 712, or the connecting plug 712 is inserted into the second circuit board 72.

[0045] After the circuit board assembly 7 is placed on the powertrain carrier 40, one of the fixing screws 6.1, 6.2, 6.3 can be inserted into one of the fixing openings 721, 722, 723 provided on the upper side of the second circuit board 72. Each of these fixing openings 72 opens into one of the insertion sleeves of the second circuit board 72. Once the fixing screws 6.1, 6.2, 6.3 pass through the spacer sleeves 741, 742, 743 and the insertion sleeves 7131, 7132, 7133 of the first circuit board 71, respectively, they can be screwed into the corresponding holes 407.1, 407.2, 407.3 of the powertrain carrier 40.

[0046] After the circuit board assembly 7 is assembled into the first housing portion G1, the two circuit boards 71, 72 are fixed in position relative to each other by the circuit board holder 74 and are further structured to support each other. This prevents the circuit boards 71, 72 from tilting backward when other components, particularly the second housing portion G2, are subsequently assembled into the first housing portion G1. Particularly in assembling the drive unit A, other components can be brought into contact with portions of the circuit board assembly 7 in a process-reliable manner without concern for the circuit boards 71, 72 being misaligned relative to each other.

[0047] In the embodiments shown in FIGS. 11 and 12 , the circuit board holder 74 has a different configuration for supporting and connecting the two circuit boards 71 ​​and 72. In the embodiments shown in FIGS. 8 to 10 , the connection structure 740 connecting the spacer sleeves 741, 742, and 743 is formed by three support posts defining a central triangular opening. In the embodiment shown in FIGS. 11 and 12 , the connection structure 740 is formed by a continuous connection surface between the three spacer sleeves 741, 742, and 743. A plug and positioning opening 744 is formed in the connection surface of the connection structure 740, and the connection plug 712 is received therein in a form-fitting manner. In this case, the circuit board holder 74 can only be attached to the circuit boards 71 ​​and 72 in one orientation relative to the connection plug 712. Therefore, the orientation of the circuit board holder 74 relative to the circuit boards 71 ​​and 72 is uniquely determined via the plug and positioning opening 744 for the connection plug 712.

[0048] 12, after the spacer sleeves 741, 742, 743 are placed on the support 407 of the power train carrier 40, they are aligned with the bore holes 407.1, 407.2, 407.3, so that the fixing screws 6.1, 6.2, 6.3 inserted through the fixing openings 721, 722, 723 of the second circuit board 72 pass through the spacer sleeves 741, 742, 743 of the circuit board holder 74 and are screwed into the bore holes 407.1, 407.2, 407.3, fixing the pre-assembled circuit board assembly 72 to the gear carrier 40. [Explanation of symbols]

[0049] 1 Support position 10 bottom 11 Side wall 2 stator 23 Coil 3 rotors 30 rotor shaft 31 (Motor) Pinion 4 Powertrain Assembly 40 Transmission mechanism carrier (carrier part) 407 Support part 407.1, 407.2, 407.3 Bore holes (connection positions) 5 Support Shield 6.1, 6.2, 6.3 Fixing screws 7 Circuit Board Assembly 71 (Main) Circuit Board 712 Connection plug (connection member) 7131, 7132, 7133 Insert sleeve (shape fitting member) 72 (additional) circuit boards 721, 722, 723 Fixing opening 7231, 7232 Insert sleeve (shape fitting member) 73 Plug connector part 74 Circuit Board Holder 740 Connection Structure 741, 742, 743 Spacer sleeve (dome with bore) 744 Plug and Locating Opening A Drive Unit B1-B3 connection position G Housing G1, G2 housing half (housing part) K power transmission components O7 Plug opening OR Rotor shaft support opening OT Pedal Axle Housing Opening T Pedal shaft (assembly)

Claims

1. A circuit board assembly (7) of a drive unit (A) of an electric bicycle, comprising: Two circuit boards (71, 72) connected to each other; a circuit board holder (74); A circuit board assembly, characterized in that one of the circuit boards (71, 72) is fixed to the circuit board holder (74), and the circuit boards (71, 72) are held at a predetermined distance from each other via the circuit board holder (74).

2. 2. The circuit board assembly according to claim 1, wherein the circuit board holder (74) comprises at least one spacer member (741, 742, 743) that defines the spacing at which the two circuit boards (71, 72) are held together.

3. 3. A circuit board assembly according to claim 2, characterized in that at least one of said circuit boards (71, 72) is connectable in a form-fitting manner to said at least one spacer member (741, 742, 743).

4. 4. The circuit board assembly of claim 3, wherein form-fitting members (7131, 7132, 7132, 7231, 7232) of the circuit boards (71, 72) are inserted into the at least one spacer member (741, 742, 743) so that at least one of the circuit boards (71, 72) and the at least one spacer member (741, 742, 742) are connected by form-fitting.

5. 5. The circuit board assembly according to claim 4, wherein the form-fitting members (7131, 7132, 7132, 7231, 7232) are inserted into openings in the spacer members (741, 742, 742).

6. 6. A circuit board assembly according to claim 2, wherein the at least one spacer element (741, 742, 743) is formed with through-openings for the passage of fastening elements (6.1, 6.2, 6.3) for fixing the circuit board assembly (7) to a carrier part (40).

7. 7. The circuit board assembly according to claim 6, wherein said at least one spacer member (741, 742, 743) is formed in a sleeve shape.

8. 8. The circuit board assembly according to claim 2, wherein the circuit board holder (7) comprises a plurality of spacer members (741, 742, 743) connected to each other via a connecting structure (740) of the circuit board holder (7).

9. 9. The circuit board assembly according to claim 1, wherein the two circuit boards (71, 72) are electrically connected to each other by a connecting member (712).

10. 10. The circuit board assembly of claim 9, wherein the connecting member (712) passes through the circuit board holder (74).

11. 11. The circuit board assembly of claim 10, wherein the circuit board holder (74) includes an opening (740) that receives and form-fits at least a portion of the connecting member (712).

12. 12. The circuit board assembly according to claim 8 and claim 11, wherein the openings (744) for the connection members (712) are formed in the connection structures (740).

13. 13. A circuit board assembly according to any one of claims 9 to 12, characterized in that the connection member is formed by at least one connection plug (712).

14. A drive unit for an electric bicycle, characterized in that it comprises an electric motor drive (2, 3) and a circuit board assembly (7) according to any one of claims 1 to 13.

15. 15. A drive unit as described in claim 14, characterized in that a plug connector section (73) having one or more plug connectors for connecting the drive unit (A) to a power source and / or higher-level control electronics of the electric bicycle is provided on one of the circuit boards (71, 72) of the circuit board assembly (7).

16. 16. A drive unit according to claim 14 or 15, characterized in that at least part of the sensor technology capable of measuring torque and / or an inertial measurement unit is provided on at least one of the circuit boards (71, 72) of the circuit board assembly (7).

17. the electric motor drive unit (2, 3) comprises a rotor (3) rotatable about a rotor axis (R) and a power train assembly (4), the power train assembly (4) having a transmission member coupled to the rotor (3) of the electric motor drive unit (2, 3); 17. A drive unit according to any one of claims 14 to 16, characterized in that the transmission member is at least partially supported on a power train carrier (40) on which the circuit board assembly (7) is fixed.

18. 18. The drive unit according to claim 17, characterized in that the at least one spacer element (741, 742, 743) of the circuit board holder (74) has through openings through which fastening elements (6.1, 6.2, 6.3) pass, and the circuit board assembly (7) is fixed to the power train carrier (40) via the through openings.

19. A method for assembling a circuit board assembly (7) to a housing part (G1) of a drive unit (A) of an electric bicycle, comprising the steps of: The circuit board assembly (7), which has two circuit boards (71, 72) and a circuit board holder (74), is pre-assembled by fixing the two circuit boards (71, 72) to the circuit board holder (74) and holding the two circuit boards at a predetermined distance by the circuit board holder (74), and then assembled into the housing part (G1).

20. The drive unit (A) comprises an electric motor drive (2, 3) having a rotor (3) rotatable about a rotor axis (R), and a power train assembly (4) having a transmission member coupled to the rotor (3) and at least partially supported on a power train carrier (40), 20. The method according to claim 19, characterized in that the power train carrier (40) is assembled to the housing part (G1) before the pre-assembled circuit board assembly (7), and then the pre-assembled circuit board assembly (7) is fixed to the power train carrier (40).

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