Drive unit for electric bicycle with radially fixed stator and assembly method

Abstract

The present invention relates in particular to a drive unit (A) for an electric bicycle, the drive unit comprising an electric motor drive having a stator (2) and a rotor (3), the rotor (3) being rotatable about its axis, the drive unit further comprising a housing part (G1) in which a support part (1) for the stator (2) is provided, the support part (1) having an inner wall (11) facing the outer surface of the casing of the stator (2). The stator (2) in the support (1) is fixed against rotation around the rotor axis by means of at least one engaging connection between the inner wall (11) of the support (1) and a component (21) of the stator (2), the engaging connection being formed by at least one first engaging connection portion (111, 112, 113, 111') of the support (1) projecting radially with respect to the rotor axis and at least one second engaging connection portion (210; 210') of the stator (2) engaging with the first engaging connection portion (111, 112, 113, 111').

Description

[Technical Field]

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

[0002] Drive units for electric bicycles are widely known, each having at least one electric motor drive. The at least one electric motor drive is used together with the drive unit to provide a drive torque generated by an external action to an output element of the drive unit. The output element is then coupled to, for example, a power transmission element. The power transmission element is connected to the rear wheel of the electric bicycle via a transmission member such as a belt or chain. The drive torque generated by the external action is typically provided in addition to a drive torque generated by muscle action applied to the pedal shaft via the pedals. Summary of the Invention

[0003] The output element and the power transmission element are usually provided on a pedal shaft assembly that includes a pedal shaft with a freewheel. Since the rotation axis of the pedal shaft is the same as that of the output element and the power transmission element, a compact design of the drive unit is possible.

[0004] At least one electric motor having a stator and a rotor is typically provided in the electric motor drive of a drive unit. The stator is accommodated in a housing of the drive unit and supported so that it cannot rotate. For this purpose, the housing forms, for example, a pot-shaped support, on which the stator is placed during assembly of the drive unit, together with the rotor, if necessary, already pre-assembled to the stator. Accurate positioning and fixing of the stator in the support on the housing side is particularly important in view of the generation of potentially destructive torques during operation of the electric motor drive. If the stator is not concentric with the rotor axis of the rotating rotor, or if the concentricity of the stator and rotor is not reliably maintained during operation of the drive unit, destructive torques can result due to stator misalignment (eccentricity). Even if the stator is fixed using additional wedge-shaped fastening elements, for example, avoidable stator misalignment can still occur. Therefore, special measures must usually be taken, and if necessary, a time-consuming additional inspection of the assembled electric motor drive is required.

[0005] Against this background, there is a need for an improved drive unit and an improved assembly method, which, on the one hand, allows the stator of an electric bicycle drive unit to be securely fixed to the housing part in a desired orientation, and, on the other hand, makes it easier to assemble the stator to the housing part.

[0006] This problem is solved by the drive unit of claim 1 and the assembly method of claim 15.

[0007] In the proposed drive unit for an electric bicycle, the stator of the electric motor drive unit is fixed to the support part of the housing part of the drive unit so as to resist rotation about a rotor axis defined by the rotor of the electric motor drive unit by means of at least one form-fit between an inner wall of the support part facing an outer surface of the stator and a component of the stator, the form-fit being formed by at least one first form-fitting portion of the support part projecting radially relative to the rotor axis and at least one second form-fitting portion of the stator engaging with the first form-fitting portion.

[0008] The proposed solution is further based on the basic idea of ​​providing a form fit between the outer profile of the stator, which is assembled to the support, and the inner wall of the support, if necessary, thereby fixing the stator against rotation around the rotor axis. By using a form-fit connection of the type proposed here, the form fit is created by simply placing the stator on the support. At the same time, the orientation of the stator relative to the support can be defined in a specific way by means of the interacting form-fitting parts, so that the stator can only be installed in one specific position on the support, i.e., in the position where two form-fitting parts can engage with each other.

[0009] The inner wall of the support can essentially surround the entire outer periphery of the stator in the circumferential direction, for example the inner wall can be formed as a completely closed structure along an annular line, but the inner wall can also essentially be at least partially interrupted, for example by separating slots.

[0010] The first form-fitting portion of the radially protruding support portion may be formed on the inner wall of the support portion and may therefore be integrally molded with the inner wall.

[0011] Basically, it is also possible to provide the support with a plurality of (at least two) first form-fitting portions that protrude in the radial direction. Each of these first form-fitting portions of the support engages with one of the at least two second form-fitting portions of the stator. The at least two second form-fitting portions may be spaced apart from one another in the circumferential direction of the stator. Thus, the stator is connected to the support on the housing side in a form-fitting manner at a plurality of positions.

[0012] In particular, when the inner wall of the support portion is continuous over the entire periphery, at least two first shape fitting portions of the support portion may be formed on the same inner wall.

[0013] In one embodiment, only three first form fitting portions are provided on the support. By providing multiple first form fitting portions, in particular only three first form fitting portions, and second form fitting portions formed on the stator and interacting with the first form fitting portions, the assembly forces acting on the stator components forming the second form fitting portions during assembly can be distributed across multiple fitting portions, in this example, three fitting portions. The three first form fitting portions of the support can be arranged at equal intervals from one another along a circumferential line around the rotor axis within the support. Thus, these three first form fitting portions are arranged on radial lines relative to the rotor axis at the support, and the lines are each spaced apart by an angle of 120° from one another.

[0014] In one embodiment, a form-fitting element is provided on at least one of the first and second form-fitting parts and form-fits into a recess of the corresponding form-fitting part of the other. On the one hand, this includes a form-fitting element provided on the first form-fitting part of the support part and form-fitting into a recess of the second form-fitting part provided on the stator side. However, this may also include variants in which the second form-fitting part provided on the stator side has a form-fitting element that form-fits into a recess of the first form-fitting part provided on the support side.

[0015] To ensure a form-fit that requires as little mounting space as possible and that can withstand sufficient loads, the form-fitting elements can be stud- or pin-shaped. For example, a corresponding form-fitting element is formed by a locking stud. When assembling the stator to the housing part, such a locking stud is inserted into a recess of the other form-fitting part, for example by plugging, in particular by press-fitting.

[0016] To ensure that the first and second form-fitting portions engage with each other when the stator is assembled to the support, it is advantageous for form-fitting elements to protrude from the support in the radial or axial direction of the rotor axis. For example, the form-fitting elements of the first form-fitting portion on the support side may protrude radially from the inner wall. Alternatively or additionally (in the latter case, for example, by form-fitting at another connecting position), the form-fitting elements of the second form-fitting portion on the stator side may protrude axially from a component of the stator on which the second form-fitting portion is provided. When the stator is assembled in an assembly direction parallel to the rotor axis, the radially protruding form-fitting elements of the first form-fitting portion on the support side can engage with recesses of the second form-fitting portion on the outer periphery of the stator that open in the assembly direction. The axially protruding form-fitting elements of the second form-fitting portion on the stator side protrude, for example, in the assembly direction parallel to the rotor axis. Thereby, by placing the stator on the support, it can automatically engage with the recess provided in the support along the assembly direction.

[0017] In a further refinement, at least one locking element is provided in the recess (of the first or second form-fitting portion). This locking element is plastically deformed when the form-fitting element engages with the recess and forms a force-fit and / or form-fit connection with the form-fitting element. Thus, when the stator is assembled to the support, the corresponding locking element is deformed due to the insertion of the form-fitting element into the recess and forms a force-fit and / or form-fit connection with the form-fitting element inserted in the recess. Such a plastically deformed locking element can further improve the fixation of the stator to the support and the prevention of rotation about the rotor axis. In this way, by utilizing the plastic deformation of the locking element, a larger interference fit can be relatively easily achieved in at least one form fit by the locking element.

[0018] The at least one locking element can be formed, for example, by a rib, in particular a so-called crimp rib, which projects into the recess so that, for example, a movement towards plastic deformation of the rib occurs when a form-fitting element is inserted therein.

[0019] To further improve or adjust the interference fit, at least two opposing locking elements may be provided on the recess edges that define the opposing recesses, such that multiple locking elements are provided in the recesses.

[0020] In one embodiment, the stator component with at least one second form-fitting portion is formed by an axial end piece of the stator in the direction of the rotor axis. The axial end piece of the stator forming the at least one second form-fitting portion may be provided at an end of the stator in the assembly direction (the direction along which the stator is assembled to the support). The axial end piece forming the at least one second form-fitting portion then faces, for example, towards a bottom part of the support in the assembly direction that faces the stator in the assembled state. For example, the axial end piece is formed by an (electrical) insulating end plate or an (electrical) insulating end ring of the stator. The axial end piece can therefore be a separate part that defines the axial end of the stator and is assembled to a base body that supports the stator coils during assembly. The corresponding axial end piece can therefore be formed as a separate part that is assembled to the base body of the stator, in particular a separate part that can be inserted into the base body.

[0021] A further aspect of the proposed solution relates to a method for assembling a stator to a housing part of a drive unit for an electric bicycle, wherein the housing part is a part of the housing of the drive unit. This housing part accommodates mechanical and electronic components of the drive unit, in particular components of the electric motor drive part of the drive unit. In particular, a support part for the stator and a rotor rotatable relative to the stator about the rotor axis is provided in the housing part, the support part having an inner wall facing an outer surface of the stator when the stator is assembled to the housing part. In the proposed solution, the stator is fixed to the support part so as not to rotate about the rotor axis by at least one form fit between the inner wall of the support part and the stator component. The form fit is formed by at least one first form fit portion formed on the support part and protruding radially, and at least one second form fit portion formed on the stator that engages with the first form fit portion during assembly of the stator to the support part.

[0022] The proposed assembly method can therefore be used in particular to assemble embodiments of the proposed drive unit, and therefore the advantages and features of embodiments of the proposed drive unit described above and below are also applicable to embodiments of the proposed assembly method, and vice versa.

[0023] For example, in one embodiment of the proposed assembly method, the stator is further fixed to the support along its outer periphery by a press-fit connection, so that the stator may for example be press-fit into the support, whereby the outer periphery of the stator contacts in a press-fit manner with a side wall of the support which may be fully continuous or at least partially interrupted in the circumferential direction.

[0024] To press the stator into the support, especially the pot-shaped support, at least a portion of the housing can be heated. This allows a temporary deformation of the outer surface of the housing for the stator to be inserted. Such heating can be limited to only a portion of the housing, resulting in localized heating. Alternatively, the entire housing can be heated to a predetermined assembly temperature (taking into account defined tolerances). For example, induction heating is suitable for targeted, process-reliable heating of the housing, especially in the industrial production of drive units. This heating can be carried out, for example, using an inductor provided in an assembly device for assembling the drive unit.

[0025] In connection with the above-described embodiment of the proposed drive unit, in one embodiment of the proposed assembly method, at least one of the first or second form-fitting portions may be provided with a form-fitting element, which is inserted into a recess of the other corresponding (second or first) form-fitting portion when assembling the stator to the support, so as to form-fit. For example, the corresponding form-fitting element may protrude from the support or from a component of the stator in the radial or axial direction of the rotor axis. In particular, the form-fitting element may protrude radially from the support or axially from the component of the stator.

[0026] In particular, at least one locking element, for example in the form of a rib, may be provided in the recess, which may be plastically deformed when the form-fitting element is inserted into the recess and form a press-fit and / or form-fit connection with the form-fitting element.

[0027] In one embodiment, at least one locking element (provided on the stator or the support) is melted by heating at least a portion of the housing before the form-fitting element is inserted into the recess. This at least localized melting of the at least one locking element can reduce the assembly force required to insert the form-fitting element into the corresponding recess. For example, one or more locking elements may protrude into the recess to such an extent that, when the locking element is in its rigid state, it cannot be overcome without irreversible destruction of at least one component of the drive unit. Therefore, the corresponding form-fitting element cannot be inserted into the recess without destruction while the one or more locking elements are in their rigid state. However, the assembly force required for plastic deformation of the one or more locking elements can be reduced by at least localized melting.

[0028] In principle, the heating of the housing may be limited to one or more second form-fitting portions of the stator, where one or more locking elements are provided. In particular, if the stator is inductively heated in some way, in particular by means of an inductor, for the heat-assisted press-fitting into the support, this induction heating may be performed to melt one or more locking elements provided in at least one second form-fitting portion of the stator. As a result, during the assembly process, the stator is press-fit into place in the housing part with the aid of heat. The stator can then be further fixed in a form-fitting manner in a relatively simple manner without unintended axial displacement, for example due to radial forces acting locally on the stator. [Brief explanation of the drawings]

[0029] The attached figures show exemplarily possible implementations of the proposed solution. In these figures: [Figure 1A] 1A and 1B show an embodiment of the proposed drive unit in perspective views from different longitudinal sides. [Figure 1B] 1A and 1B show an embodiment of the proposed drive unit in perspective views from different longitudinal sides. [Figure 2A] 1C shows a first housing part of the housing of the drive unit of FIGS. 1A and 1B as viewed from the outside. [Figure 2B] 2B shows the first housing part of FIG. 2A as viewed from the inside. [Figure 3] 1 shows the first housing portion with the stator of the electric motor drive portion of the drive unit assembled thereto. [Figure 4] The first housing part is shown in the next assembly step, where the rotor is assembled to the first housing part which already has the stator. [Figure 5] The first housing part to which the stator is assembled and the rotor is assembled is shown. [Figure 6] 1 shows the first housing part in the next assembly step, where the transmission assembly and support shield are assembled to the first housing part already containing the stator and rotor. [Figure 7] Shown is the first housing portion to which the transmission mechanism assembly is secured, and the transmission mechanism assembly to which the support shield is secured. [Figure 8] FIG. 1 is a perspective view of a pre-assembled stator of a drive unit, the stator being shown alone. [Figure 9] 9 is an enlarged view of the stator of FIG. 8, showing one of the second form-fitting portions provided on the stator side. FIG. [Figure 10]10 is an enlarged view of the first housing part, showing a first form-fitting portion of a support portion of the first housing part provided for the stator; FIG. [Figure 11] 11 is an enlarged view of a first shape-fitting portion of the support portion shown in FIG. 10. The first engagement fitting portion is formed by an engagement stud that protrudes in the radial direction. [Figure 12] 1 is an enlarged view of the first housing part already having the stator, showing the first and second form-fitting parts that engage with each other; FIG. [Figure 13] FIG. 10 is a perspective view of a first housing part of another embodiment of a drive unit, showing the inside of the first housing part. [Figure 14] 14 is a perspective view of the stator of the alternative embodiment assembled to the first housing part of FIG. 13. FIG. [Figure 15] 15 is a cross-sectional view of the first housing part of FIG. 13, with the stator of FIG. 14 assembled to the first housing part. DETAILED DESCRIPTION OF THE INVENTION

[0030] 1A and 1B show a drive unit A for an electric bicycle in different perspective views showing two different sides. The drive unit A comprises a housing G that houses electronic and mechanical components. The housing G comprises two interconnected first and second housing parts G1 and G2, each of which defines one half of the housing.

[0031] The ends of the pedal shaft T protrude from both sides of the housing G. Pedals can be attached to these ends, so that, after proper assembly of the drive unit A on the electric bicycle, a driving torque is introduced into the pedal shaft T by muscle power actuation to drive the electric bicycle. Via a power transmission element K on the pedal shaft T, in particular, the torque generated by muscle power actuation can be transmitted to the rear wheel of the electric bicycle via a transmission member such as a belt or chain, for example with the aid of a belt wheel or chain ring that is connected so as not to rotate relative to the power transmission element K. In addition, a torque generated by an external force actuation can be applied to the power transmission element K and is provided by an electric motor drive unit housed in the housing G and transmitted to the power transmission element K via a transmission mechanism housed in the housing G.

[0032] On one side formed by the first housing part G1, a plug connector part ST is visible extending from the interior of the housing G to the outside. This plug connector part ST has one or more plug connectors for connecting the drive unit A to a current source and / or higher-level control electronics of the electric bicycle.

[0033] 2A and 2B show the first housing part G1 for the embodiment of the proposed drive unit A, showing the first housing part G1 alone from different perspectives. The first housing part G1 is formed as a housing half which, in combination with the second housing part G2, defines a housing space in which the electronic and mechanical components of the drive unit A are accommodated. For connection with the second housing part G2, in this example, for connection with the second housing half, the first housing part G1 has a plurality of fastening positions B1, B2, and B3 (at least two, in this example, three) distributed on the outer periphery of the first housing part G1. In addition, 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 are formed in the first housing part G1. The rotor shaft 30 is part of the rotor 3 and is rotatable relative to the stator 2 of the electric motor drive unit around a rotor axis that coincides with the axis of the rotor shaft 30, and provides a drive torque generated by an external force operation (see particularly Figures 4 to 7).

[0034] As can be seen from the inside of the first housing part G1 in particular in Figure 2B, the first housing part G1 forms a (motor) support 1 with a support pot, which is provided in particular for arranging a stator 2 of an electric motor drive.

[0035] The pot-shaped support 1 or the support in which the support pot is formed inside the first housing part G1 has an inner wall 11 that completely surrounds the support opening OR for the rotor shaft 30 (i.e., around the rotor axis of the rotor 3 defined by the rotor shaft 30) along an annular line. This inner wall 11 extends perpendicularly to the bottom 10 of the support 1. In this example, the bottom 10 is exemplarily formed in the form of flower-like ribs extending toward the support opening OR. A first form-fitting section is formed on the inner wall 11 of the support 1, with a plurality—in this example, exactly three—of radially protruding engagement studs 111, 112, and 113. The engagement studs 111, 112, and 113 are equally spaced from one another in the region of the inner wall 11 near the bottom of the support 1 and are each located at the same height.

[0036] In this example, the engagement studs 111, 112, and 113 function to form a concave-convex form fit with the components of the stator 2 when the stator 2 is assembled to the support 1 as intended. The three form fits thus formed secure the stator 2 within the pot-shaped support 1 of the first housing part G1 against rotation about the rotor axis and against unwanted axial displacement. The engagement studs 111, 112, and 113 precisely engage the outer periphery of the stator 2, so that the subsequent insertion of the rotor 3 into the stator 2 already assembled in the first housing part G1 is not hindered. This allows the individual components of the electric motor drive to be assembled in stages. For example, the multi-component stator 2 and the multi-component rotor 3 can be pre-assembled independently of each other and then sequentially assembled into the first housing part G1.

[0037] In Figure 3, the stator 2 has already been inserted into the first housing part G1 and fixed in place during assembly of the drive unit A. Details of the fixing of the stator 2 to the support will be explained in more detail below, with particular reference to Figures 8 to 12.

[0038] As shown in Figure 4, in the next assembly step, the rotor 3, which is made up of multiple components, is inserted into the stator 2, i.e., the first housing part G1. The rotor 3 includes a rotor unit with magnets covered in laminated plates and a rotor shaft 30. A (motor) pinion 31 is either integrally formed with the rotor shaft 30 or is non-rotatably fixed thereto, so that the driving torque generated by the electric motor drives 2, 3 can be transmitted via the pinion 31.

[0039] When the drive unit A is assembled as intended, a driving torque generated by an external action is transmitted from the pinion 31 to a transmission mechanism connected to the power transmission element K. In this example, at least a part of this transmission mechanism is constituted by a pre-assembled transmission mechanism assembly 4. As shown in FIG. 5, this transmission mechanism assembly 4 is assembled to the first housing part G1 after the stator 2 and the rotor 3 have been arranged on the support part 1 as intended.

[0040] In this example, a plurality of meshing gears are rotatably supported on the transmission mechanism carrier 40 of the transmission mechanism assembly 4. In particular, a gear configured to mesh with the pinion 31 when the transmission mechanism assembly 4 is assembled to the first housing part G1 as intended is rotatably supported on the transmission mechanism carrier 40. The corresponding transmission gears can be pre-assembled on the transmission mechanism carrier 40.

[0041] If the transmission mechanism assembly 4 is fully assembled in advance, the assembly is assembled to the first housing part G1 in accordance with the assembly process shown in Fig. 6 and fixed in an appropriate position within the first housing part G1 using fastening elements in the form of, for example, screws or bolts. Then, the support part shield 5 is placed on the transmission mechanism assembly 4 inserted into the first housing part G1 in this way and fixed to the transmission mechanism assembly 4.

[0042] After the assembly of further mechanical and electronic components to the first housing part G1, the second housing part G2 is attached and fixed to the first housing part G1, thereby hermetically closing the housing space of the housing G, which accommodates the transmission mechanism assembly 4 and the motor drives 2, 3.

[0043] 8 to 12 show in more detail the fastening of the stator 2 to the pot-shaped support 1 of the first housing part G1. In this example, the stator 2 has a multi-component structure and includes a base body 20 that supports the coils 23 of the stator 2. In this example, the stator 2 has a multi-component structure, including, among other things, a base body 20 that supports the coils 23 of the stator 2. So-called insulating rings 21 and 22 are attached to both sides of this base body 202 as first and second axial end members relative to the rotor axis. The first insulating ring 21 defines the first axial end member of the stator 2 in the assembly direction and faces the bottom 10 of the support 1 when the stator 2 is assembled as intended. The second insulating ring 22 defines the other axial end member of the stator 2 and faces the transmission mechanism assembly 4 when the stator 2 is assembled as intended. For example, the cables and contacts for connecting the electric motor drives 2, 3 to the control electronics of the drive unit A are routed through the location of the second insulating ring 22. The first insulating ring 21 (as well as the second insulating ring 22 in this example), which is provided in particular for insulating the coil 23, is made of glass-fiber reinforced plastic in order to optimize weight and ensure sufficient load-bearing capacity.

[0044] In the illustrated embodiment, a positioning pin 220 is provided on the second insulating ring 22. The positioning pin 220 protrudes axially from the stator 2. When the transmission mechanism assembly 4 is attached to the first housing part G1, the positioning pin 220 is engageable with a corresponding opening or recess in the transmission mechanism carrier 40. Therefore, the positioning pin 220 determines the attitude of the transmission mechanism carrier 40, which is assembled into the first housing part G1, and the transmission mechanism assembly 4 including the transmission mechanism carrier 40, relative to the stator 2.

[0045] The multiple second form-fitting portions are configured as recesses having the form of engagement slots 210 and are provided in the first (lower) insulating ring 21 at intervals in the circumferential direction. Three of these engagement slots 210 engage with engagement studs 111, 112, and 113 protruding radially from the support part 1 when the stator 2 is inserted into the support part 1. Because the engagement slots 210 of the stator 2 are open in the assembly direction and the radial direction, the engagement slots 210 formed in the first insulating ring 21 of the stator 2 can be fitted (inserted) onto the engagement studs 111, 112, and 113 on the support part side. This allows the stator 2 to be fixed to the housing part G1 in the intended mounting orientation when the stator 2 is inserted as far as possible toward the base 10 in the assembly direction.

[0046] To ensure that the fixation achieved by each form fit is sufficiently load-bearing, each form fit is provided with an interference fit. This interference fit is assisted by locking elements in the form of crimping ribs Q1-Q4 provided in each engagement slot 210. Thus, as shown in the enlarged view of FIG. 9, each engagement slot 210 is defined by two slot edges 210.1 and 210.2 that face each other in the circumferential direction. Each slot edge 210.1 and 210.2 is provided with a pair of crimping ribs Q1, Q2 or Q3, Q4 that project toward the center of the recess 210. As a result, each engagement slot 210 is provided with two pairs of clamping ribs Q1, Q2 and Q3, Q4 that project opposite each other.

[0047] The dimensions of the engagement studs 111, 112, and 113 and the dimensions of the engagement slots 210 having the crimping ribs Q1-Q4 are set so that insertion of the engagement stud 111, 112, or 113 into the corresponding engagement slot 210 is possible only by press-fitting the stud into the engagement slot 210 and plastically deforming the crimping ribs Q1-Q4 of the engagement slot 210. All three engagement studs 111, 112, and 113 are securely received in the three corresponding engagement slots 210 of the stator 2 by corresponding interference fits, both form-fit and press-fit. This results in static overdetermination due to the circumferentially distributed arrangement of the three engagement studs 111, 112, and 113. Therefore, when the stator 2 is form-fitted to the inner wall 11 via the three engagement studs 111, 112 and 113 with an assembly clearance, only two of the three engagement studs 111, 112 and 113 actually engage.

[0048] 11 and 12, the engaging stud 112 is press-fitted in the axial direction from the side opposite to the assembly direction, causing the crimping ribs Q1 to Q4 to plastically deform on the side surfaces 112a and 112b of the engaging stud 112. The deformed crimping ribs Q1 to Q4 are then connected to these side surfaces 112a and 112b in a press-fitted state.

[0049] The interference fit in this example, provided by the crimping ribs Q1-Q4 in combination with the dimensions of the engaging studs 111, 112 and 113, is selected so that it cannot yield in the rigid state (without irreversibly damaging at least one of the components), and in particular is set so that it cannot yield without damaging the first insulating ring 21 that forms the engaging slot 210.

[0050] In this example, the crimping ribs Q1 to Q4 are melted during assembly of the stator 2 to the support 1 so that the engagement studs 111, 112, and 113 can be inserted into the corresponding engagement slots 210 of the first insulating ring 21 of the stator 2 while deforming the crimping ribs Q1 to Q4. Basically, heating may be performed only in localized areas of the first insulating ring 21. In contrast, the illustrated embodiment employs a configuration in which the entire housing G1 is induction heated. In this case, the crimping ribs Q1 to Q4 in each engagement slot 210 are melted by the induction-heated engagement studs 111, 112, and 113 during assembly. The housing G1 is heated at least at its outer periphery via an inductor. Such an inductor can be provided, for example, in an assembly device on which the first housing part G1 is positioned and fixed for the assembly process.

[0051] In this example, the housing G1 may be induction heated to press the stator 2 into the support part 1, so that the stator 2 abuts against the inner wall 11 that surrounds the support part 10 in the circumferential direction, and the stator 2 is press-fit at its outer periphery. The induction heating of the housing G1 to form such a press-fit in the support part 1 also melts the crimping ribs Q1 to Q4 provided in the engagement slit 210, functioning as an additional means for preventing twisting of the stator 2 relative to the support part 1 and the resulting axial misalignment (eccentricity).

[0052] 13, 14, and 15, the form-fitting between the inner wall 11 of the support part 1 and the stator 2 arranged on the support part 1 is also provided in the support part 1 of the first housing part G1. However, in contrast to the above-described embodiment, in this example, only a single form-fitting is provided, which is constituted by a radially protruding protrusion 111' in the first form-fitting part of the inner wall 11 and an engaging part 210' in the second form-fitting part on the stator 2 side. Furthermore, the stator-side engaging part 210' may be formed as a part of the base body 20 that protrudes in the axial direction, rather than as an insulating ring 21.

[0053] 13 to 15, the engagement portion 210' of the stator 2 has a recess with a central engagement stud 210A. When the stator 2 is inserted into the support portion 1 (by heat), when the stator 2 is inserted into the support portion 1 to the maximum extent toward the bottom portion 10 along the assembly direction, the radially protruding protrusion 111' of the inner wall 11 engages with the recess of the engagement portion 210'. At this time, the engagement stud 210A on the stator side also engages so as to form-fit with the recess of the protrusion 111' formed as the engagement opening 111A. Due to the form-fit obtained in this manner, the stator 2 is fixed to the first housing portion G1 in the intended mounting position, as in the above-described embodiment, and rotation about the rotor axis is restricted. At this time, no radial force that could lead to axial misalignment of the stator 2 is applied to the stator 2, thereby preventing undesired destructive torque from being generated during operation of the electric motor drive units 2 and 3.

[0054] Similar to the form fit of the previous embodiments, at least one locking element, for example in the form of a crimping rib that is plastically deformed during assembly to enhance the interference fit, may be formed in a recess in the engagement part 210' with the central engagement stud or in the engagement opening 111A in the support part 1. [Explanation of symbols]

[0055] 1 Support part 10 bottom 11 Side wall 111, 112, 113 Engagement stud (first shape fitting portion) 111' Overhanging part (first shape fitting part) 111A Engagement opening / recess 112a, 112b side 2 stator 20 Base body 21 First insulating ring 210 Engagement slot / recess (second shape fitting portion) 210.1, 210.2 Slot edge (recess edge) 210' Engagement portion (second shape fitting portion) 210A Engagement Stud 22 Second insulating ring 220 Locating Pin 23 Coil 3 rotors 30 rotor shaft 31 (Motor) Pinion 4 Transmission Mechanism Assembly 40 Transmission carrier 5 Support Shield A Drive Unit B1~B3 connection position G Housing G1, G2 Half of the housing (housing part) K power transmission element OR Support opening for rotor shaft Support opening for OT pedal axle Q1~Q4 Crimping rib (locking element) ST plug connector T Pedal shaft assembly U circumferential direction

Claims

1. A drive unit for an electric bicycle, an electric motor drive including a stator (2) and a rotor (3), the rotor (3) being rotatable about a rotor axis; a housing portion (G1) in which a support portion (1) for the stator (2) is provided, The support portion (1) has an inner wall (11) facing an outer surface of the stator (2), The stator (2) is fixed to the support (1) against rotation around the rotor axis by means of at least one form fit between the inner wall (11) and a component (21) of the stator (2), the form fit being formed by at least one first form fit portion (111, 112, 113, 111') of the support (1) projecting in a radial direction relative to the rotor axis and at least one second form fit portion (210, 210') of the stator (2) engaging with the first form fit portion (111, 112, 113, 111'). A drive unit characterized by:

2. At least two radially protruding first form-fitting portions (111, 112, 113) are provided on the support, and each of the first form-fitting portions engages with one of at least two second form-fitting portions (210) of the stator (2).

2. The drive unit of claim 1.

3. The at least two second shape-fitting portions (210) are spaced apart from each other in the circumferential direction of the stator (2).

3. The drive unit according to claim 2.

4. At least two first shape-fitting portions (111, 112, 113) of the support portion (1) are formed on the same inner wall (11).

4. A drive unit according to claim 2 or 3.

5. Only three first shape-fitting portions (111, 112, 113) are provided on the support portion (1). Drive unit according to any one of claims 2 to 4.

6. The three first shape-fitting portions (111, 112, 113) are provided at equal intervals along an outer circumferential line surrounding the rotor axis within the support portion (1).

6. The drive unit according to claim 5.

7. At least one of the first and second form-fitting portions (111, 112, 113, 210, 111', 210') is provided with a form-fitting element (111, 112, 113, 210A) that form-fits and engages in a recess (210, 111A) of the corresponding form-fitting portion of the other. Drive unit according to any one of claims 1 to 6.

8. The form-fitting elements (111, 112, 113, 210A) are formed in the shape of a stud or pin, more specifically in the shape of an engaging stud (111, 112, 113, 210A).

8. The drive unit according to claim 7.

9. The form-fitting elements (111, 112, 113, 210A) project radially or axially relative to the rotor axis at the support (1), more particularly from the inner wall (11) or from a component (21) of the stator (2).

9. A drive unit according to claim 7 or 8.

10. At least one locking element (Q1-Q4) is provided in the recess (210, 111A), and the locking element is plastically deformed by the action of the form-fitting element (111, 112, 113, 210A) engaging with the recess (210, 111A) to form a press-fit and / or form-fit with the form-fitting element (111, 112, 113, 210A). Drive unit according to any one of claims 7 to 9.

11. The at least one locking element (Q1-Q4) is formed by a crimping rib.

11. The drive unit of claim 10.

12. At least two opposing locking elements (Q1, Q3, Q2, Q4) are provided on opposing recess edges (210.1, 210.2) defining the recess (210, 111A).

12. A drive unit according to claim 10 or 11.

13. The component of the stator (2) including the at least one second form-fitting portion (210, 210') is formed by an axial end member (21) of the stator (2) with respect to the rotor axis. Drive unit according to one of claims 1 to 12.

14. The axial end members are formed by insulating end plates or insulating end rings (21) of the stator (2).

14. The drive unit of claim 13.

15. A method for assembling a stator (2) to a housing portion (G1) of a drive unit (A) for an electric bicycle, comprising the steps of: a support portion (1) for the stator (2) and a rotor (3) rotatable around a rotor axis relative to the stator (2) is provided in the housing portion (G1), the support portion (1) having an inner wall (11) facing an outer surface of the stator (2) in a state where the stator (2) is assembled to the housing portion (G1); The stator (2) is fixed to the support (1) against rotation about the rotor axis by at least one form fit between an inner wall (11) of the support (1) and a component (21) of the stator (2), the form fit being formed by at least one first form fit portion (111, 112, 113, 111') projecting radially from the support (1) and at least one second form fit portion (210, 210') of the stator (2) engaging with the first form fit portion (111, 112, 113, 111') during assembly of the stator (2) to the support (1). A method characterized by:

16. The stator (2) is further fixed to the support (1) along its outer periphery by a press-fit connection.

16. The method of claim 15.

17. The stator (2) is press-fitted into the support part (1) while at least a part of the stator (2) is heated.

17. The method of claim 16.

18. 18. The method of claim 17, wherein the heating is performed using an inductor.

19. At least one of the first and second form-fitting portions (111, 112, 113, 210, 111', 210') is provided with a form-fitting element (111, 112, 113, 210A), and when the stator (2) is assembled to the support portion (1), the form-fitting element is inserted into the recess (210; 111A) of the other corresponding form-fitting portion so as to form-fit.

19. The method according to one of claims 15 to 18.

20. The form-fitting elements (111, 112, 113, 210A) project radially or axially relative to the rotor axis at the support (1), more particularly from the inner wall (11) or from a component (21) of the stator (2).

20. The method of claim 19.

21. At least one locking element (Q1-Q4) is provided in the recess (210, 111A) and plastically deforms during insertion of the form-fitting element (111, 112, 113, 210A) into the recess (210, 111A) to form a press-fit and / or form-fit with the form-fitting element (111, 112, 113, 210A).

21. The method of claim 19 or 20.

22. The at least one locking element (Q1-Q4) is formed by a crimping rib.

22. The method of claim 21.

23. At least two opposing locking elements (Q1, Q3, Q2, Q4) are provided on opposing recess edges (210.1, 210.2) defining the recess (210, 111A).

23. A drive unit according to claim 21 or 22.

24. At least a portion of the stator (2) is heated before the form-fitting element (111, 112, 113, 210A) is inserted into the recess (210, 111A), thereby melting the at least one locking element (Q1-Q4).

24. The method of claim 17 or 18 and one of claims 21 to 23.

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