Power transmission assembly for transmitting power to a rotor assembly of an externally excited electric machine, method for pre-installing a power transmission assembly, method for pre-installing a rotor assembly comprising the power transmission assembly, and externally excited electric machine comprising the rotor assembly

Abstract

The invention relates to a power transmission assembly (10), in particular an inductive power transmission assembly (10), and to a rotary transformer for transmitting power to a rotor assembly (20) of an externally excited electric machine (30), comprising a carrier lance (4), which is connected to a primary assembly (3); a bearing end (1); and an inner installation securing means (2), which pre-installs the primary assembly (3) in the bearing end (1) and remains in the bearing end after the power transmission assembly (10) is installed.

Description

[0001] Power transmission arrangement for power transmission to a rotor arrangement of a separately controlled electrical machine, method for pre-assembling a

[0002] Power transmission arrangement, method for pre-assembling a rotor arrangement with the power transmission arrangement and externally controlled electrical machine with the rotor arrangement

[0003] In the field of separately excited electric motors, power transmission arrangements are playing an increasingly important role as exciters, as they make permanent magnets or rare earths unnecessary.

[0004] In separately excited electric motors, the magnetic rotor field is generated by a current flowing through coils in the moving rotor. In commonly used drives, the electrical energy is transferred from the stationary to the rotating system using conductive slip rings.

[0005] An alternative to conductive energy transfer is offered by separately excited electric motors, where energy transfer occurs inductively. This eliminates the need for both permanent magnets and sliding contacts.

[0006] The current is transferred to the rotor via an inductive transformer. The transformer is powered by an alternating voltage from the stator. The alternating voltage is converted to direct voltage on the rotor side via a rectifier for the rotor's magnetic coils. The magnetic coils then induce a rotor magnetic field, which interacts with the stator magnetic field. This allows the motor to generate torque. The magnetic coils replace the permanent magnets. The system consisting of the inductive transformer and rectifier can also be referred to as an inductive exciter.

[0007] Electric motors are often subject to strict space constraints. However, the design of inductive exciters is limited because all moving components in the exciter must have very high speed stability. The speeds in the exciter can range from 18,000 to 24,000 revolutions per minute. Ferrite, a brittle material, is often used in exciters for the cores of the magnetic coils. This, in particular, results in significant limitations in design freedom with regard to speed stability.

[0008] When using primary and secondary ferrites for inductive excitation of a synchronous motor, a defined air gap often has to be set on the electric motor. This ensures that the ferrites do not touch each other, as this could cause damage. On the other hand, for high-power electric motors, it may be necessary to ensure a defined distance between the primary and secondary arrangements in order to transfer the desired currents to the rotor.

[0009] Furthermore, for the space-neutral integration of an inductively excited SESM rotor, for example, into the system installation space of a permanent-magnet machine, the transformer, i.e., the inductive exciter, must be arranged within the hollow rotor shaft, which can be composed of several parts. The rotor shaft consists of a central part and a side part, which contains the bearing seat for the rotor shaft. It may be desirable to retain the rotor bearing in terms of bearing type, bearing size, and bearing spacing, for example, to maintain modular compatibility with permanent-magnet rotors.

[0010] To ensure the required transmission of inductive currents, a certain minimum diameter of the transformer may be necessary. This diameter then determines the inner diameter of the central part of the rotor hollow shaft in the axial area below the stator's laminated core.

[0011] However, the inner diameters of the specified rotor bearings may be smaller than the inner diameter of the hollow shaft in the central area, which is why the transformer or the secondary side must be mounted into the rotor shaft before a multi-part rotor shaft can be assembled, or the side part of the hollow rotor shaft can be mounted. This also applies to the primary side of the inductive rotary transformer if it has a larger diameter in the area below the rotor bearing on the side where the transformer is located than a possible inner diameter of the rotor shaft or a side part of the rotor shaft, which could be, for example, a bearing end and tapers accordingly.

[0012] Accordingly, the stator-fixed, non-rotating primary side of the transformer must be inserted into the rotor before joining, finishing and completing it, since it will no longer fit through the lateral opening of the hollow shaft later.

[0013] Furthermore, it must be ensured that the primary side of the inductive transformer is held securely enough to prevent it from being damaged during motor manufacturing, for example, when inserted into the hollow rotor shaft, or damaging another part. Furthermore, it must be ensured that the primary side of the transformer is positioned sufficiently precisely relative to the secondary side during operation to maintain the previously defined air gap and prevent contact between the primary and secondary ferrites, as this could cause damage to the primary and secondary ferrites, or even damage the rotor bearing.

[0014] Previous arrangements and assembly methods are unable to secure the primary side to the stator before joining a bearing end or side part of a rotor shaft, or to position and secure the primary side relative to the rotor-side components, such as the secondary side, which is non-rotatably connected to the rotor. As a result, the primary side sits loosely in the hollow shaft and can thus be damaged. "Stator-secure" here means, for example, that the primary side of the transformer does not rotate with it.

[0015] The object of the present invention is therefore to provide a power transmission arrangement, a rotor arrangement, and a separately excited electrical machine in which the above-mentioned disadvantages are at least partially reduced. This object is achieved by a power transmission arrangement according to claim 1, a method for preassembling a power transmission arrangement according to claim 7, a method for preassembling a rotor arrangement according to claim 8, a method for assembling a separately excited electrical machine according to claim 9, and a motor vehicle according to claim 11.

[0016] Further aspects and features of the present invention emerge from the dependent claims, the accompanying drawings and the following description of embodiments.

[0017] According to a first aspect, the present invention provides a power transmission arrangement, in particular an inductive power transmission arrangement, for transmitting power to a rotor arrangement of a separately excited electric machine, comprising:

[0018] - a carrier lance connected to a primary assembly;

[0019] - a storage end, and

[0020] - an internal assembly lock that fixes the primary assembly in the bearing end in a pre-assembly position and remains there after assembly of the power transmission assembly.

[0021] The term "power transmission arrangement" describes an exciter or exciter of an electrical machine. The power transmission arrangement generally serves to induce electrical energy from power electronics into the rotor winding. The power transmission arrangement can be an exciter, for example, an inductive exciter, and is designed to transmit power to a rotor assembly of a separately excited electrical machine. The separately excited electrical machine can be an electric motor.

[0022] The power transmission arrangement according to the invention comprises a support lance connected to a primary assembly. The connection is a rotationally fixed connection. The support lance can be designed in the form of a bolt and can have a diameter of 3 to 15 mm. The support lance can also be configured such that it has different diameters in longitudinal sections.

[0023] The primary assembly can be connected to the support lance. For example, the primary assembly can be secured to the support lance by a retaining ring. The retaining ring can be a nut. The connection can also be made by gluing, welding, and the like. There can be more than one connection and / or connection type between the primary assembly and the support unit.

[0024] The length of the support lance can depend on the installation space of the electrical machine and / or the length of the secondary assembly. The support lance can be designed so that it can be connected to a machine housing of the electrical machine.

[0025] The support lance can have a recess for routing cables. The recess can be configured, for example, as a groove or a hole through which the connections and / or cables are routed.

[0026] The primary arrangement can be the primary side of an inductive transformer and can comprise a primary winding and a primary ferrite. The primary winding can be arranged in a rotationally fixed manner around the primary ferrite. The primary ferrite can be cylindrical. The primary ferrite can have a T-shaped cross-section.

[0027] The power transmission arrangement according to the invention further comprises a bearing end. A bearing end is, for example, an unused side part of a hollow rotor shaft. The bearing end can be tapered and, for example, have a funnel-shaped cross-section. The bearing end can be made of the same material as a cylindrical part of the hollow rotor shaft.

[0028] The bearing end can be the side part of a hollow rotor shaft, wherein the bearing end tapers to provide installation space for the rotor bearing. According to the invention, the support lance connected to the primary assembly is pre-assembled to the bearing end by means of an assembly lock, wherein the assembly lock remains in the bearing end after final assembly of the power transmission assembly according to the invention. The assembly lock is, for example, an internal assembly lock. The assembly lock can be made of a flexible material, such as a plastic. The assembly lock can be an elastomer or rubber. The assembly lock can be designed to fix the primary assembly in a pre-assembly position on the bearing end by means of an interference fit. The assembly lock can be annular. The assembly lock can comprise individual knobs, grooves or slots in order to set a certain elasticity in the radial direction through the shape.The assembly lock can be designed to connect the primary ferrite to a bearing end of a rotor shaft in a tilt-resistant manner.

[0029] The assembly lock can run in a groove along an inner diameter of the bearing end and grip the outer diameter of a ferrite core of a primary arrangement by an interference and thus fix it in a pre-assembly position in the bearing end.

[0030] The primary assembly may be pre-assembled with the support lance and this may be pre-assembled in the bearing end.

[0031] In one embodiment, in addition to the mounting retainer described above, the power transmission assembly includes a further, external mounting retainer that pre-assembles the support lance into the bearing end. The support lance can be connected to the primary assembly. The external mounting retainer can have a function, such as a sealing function.

[0032] The outer assembly lock can be designed to stabilize the support lance against tilting during later assembly of the primary arrangement in a functional position. The outer assembly lock can serve as a guide element for the support lance with the primary ferrite or the primary arrangement connected to the support lance during final assembly of the power transmission arrangement or assembly of a rotor. In one embodiment of the power transmission arrangement according to the invention, the outer assembly lock can be removed from the bearing end, for example after final assembly of the rotor. If the assembly lock no longer fulfills a further function, such as a sealing function, it can be removed from the power arrangement after assembly in a functional position. The outer assembly lock can also be designed to fix a pre-assembled bearing end or a side part of a rotor hollow shaft (with connected support lance) until final assembly.

[0033] In a further embodiment, the power transmission assembly comprises a hollow rotor shaft having a cylindrical portion with a secondary assembly. The hollow rotor shaft may, for example, be provided with a tapered end or bearing end, or a side portion, for example, as a cylindrical hollow shaft. The cylindrical hollow shaft may be surrounded by a stator-side laminated core with stator-side windings or the stator.

[0034] Furthermore, the power transmission arrangement according to the invention has a secondary arrangement. The secondary arrangement can be the secondary side of an inductive transformer and can comprise a secondary winding and a secondary ferrite. The secondary arrangement can be cylindrical. The secondary arrangement can have a U-shaped cross-section.

[0035] In one embodiment, the cylindrical part of the hollow rotor shaft has an inner and an outer securing element on an inner circumference. The securing elements can be configured to fix the secondary assembly in the hollow rotor shaft. The securing elements can be annular.

[0036] In a further embodiment, the cylindrical part of the hollow rotor shaft further comprises a rectifier unit and a protective circuit. The rectifier unit can be in contact with a protective circuit, which can also be held in the hollow rotor shaft by means of the securing elements according to one embodiment. Further separating elements or insulating and protective devices can also be mounted in the cylindrical part of the rotor shaft.

[0037] The individual components of the power transmission arrangement according to the invention, for example for the cylindrical part of the hollow rotor shaft, can be pre-assembled therein.

[0038] In a further aspect, the present invention provides a method for pre-assembling a bearing end for the power transmission arrangement according to the invention, comprising:

[0039] - Providing the end of the warehouse;

[0040] - Connecting the carrier lance to the primary assembly;

[0041] - securing the primary assembly inside the bearing end with the internal assembly lock; and

[0042] - Fasten the support lance to an outer end of the bearing end with the outer mounting lock.

[0043] The primary assembly can be connected to the support lance by axial clamping with a nut. This can be a welded or adhesive connection.

[0044] The primary assembly can be secured inside the bearing end, for example, by fixing the primary ferrite with an internally applied oversize.

[0045] Furthermore, in the method according to the invention, the carrier lance is fixed in a pre-assembly position by the external assembly lock.

[0046] The bearing end can be pre-assembled with the primary assembly using the method described here. A support lance can be designed so that it can be connected to a housing part of an electrical machine. The bearing end can thus be provided as a pre-assembled component. This results in greater flexibility of the component, as the primary assembly is securely held in a pre-assembly position and has an assembly lock that allows for safe and secure guidance during final assembly of the component. "Safely guided" means, for example, in such a way that the primary ferrite and the secondary ferrite cannot collide during final assembly of the power transmission assembly.

[0047] In a further aspect, the present invention provides a method for pre-assembling a rotor arrangement, comprising the bearing end described here, connected to the primary arrangement and support lance in the pre-assembly position and further comprising the cylindrical part of the hollow rotor shaft, comprising the secondary arrangement, the rectifier unit and the protection circuit, wherein the bearing end is connected to the cylindrical part of the hollow rotor shaft.

[0048] A connection here can be a welded joint, for example. The connection can also be an adhesive joint or a press connection.

[0049] The rotor assembly may be in a pre-assembly position. A pre-assembly position means, for example, that the primary and secondary assemblies are not yet positioned to perform their function, for example, as an inductive transformer.

[0050] The pre-assembly position of the rotor assembly according to the invention can be designed to ensure subsequent functionality, for example, achieving and maintaining a defined air gap between the primary assembly and the secondary assembly. A rotor assembly can be pre-assembled such that the carrier lance with the primary ferrite can be pushed out of the bearing end.

[0051] In a further aspect, the present invention provides a method for assembling an electrical machine, comprising:

[0052] - Providing the rotor arrangement according to the invention, e.g. in a pre-assembly position;

[0053] - Inserting the rotor into a housing of the electrical machine; - Pushing the support lance out of the inner assembly lock of the bearing end into the cylindrical part of the hollow rotor shaft into a functional position, whereby the inner assembly lock remains in the bearing end; and

[0054] - Fixing the support lance to the housing of the electrical machine.

[0055] Pushing out into a functional position can, for example, mean a position in which the primary assembly and the secondary assembly have a defined air gap through which the power is transmitted inductively and which is stabilized against axial and radial displacement or movement of the rotor. A functional position can be defined by the length of the support lance and a stop point on the inside of the rotor hollow shaft.

[0056] The inner assembly lock no longer serves a function in the finished or finally installed rotor, but is no longer accessible from the outside. The inner assembly lock remains inside the bearing end.

[0057] The support lance can be attached to the machine housing, for example, by screwing. This eliminates the need for a bearing in the rotor shaft.

[0058] In one embodiment of the method according to the invention, the outer assembly lock at the outer end of the bearing end can be removed.

[0059] The (pre-)assembly of the secondary assembly and the (pre-)assembly of the primary assembly can be performed as parallel process steps. However, the process can also be designed so that the process steps are carried out sequentially, without requiring a specific sequence.

[0060] The primary and secondary assemblies can be present as preassembled parts or partially preassembled. Preassembled here means, on the one hand, the presence as a ferrite and winding, as well as a pre-assembly with other functional units of the power transmission assembly described herein. In a further aspect, the present invention provides a rotor assembly comprising the power transmission assembly according to the invention. In a further aspect, the present invention provides a separately excited electrical machine comprising the rotor assembly. In a further aspect, the present invention provides a vehicle comprising the separately excited electrical machine.

[0061] By using such a designed rotor and its assembly concept, as well as the method for assembling the power transmission arrangement presented here, it can be ensured that the primary side is held securely enough to prevent it from being damaged during handling and the manufacturing processes between insertion into the rotor shaft and installation of the rotor in the housing, or damaging any other part.

[0062] Furthermore, a rotor designed in this way and its assembly concept can ensure that the primary side of the transformer is positioned with sufficient accuracy relative to the secondary side during operation.

[0063] Furthermore, the power transmission arrangement described herein eliminates the need for additional bearings between the rotor- and stator-fixed parts of the inductive transformer, allowing for better use of installation space and cost savings. Furthermore, a power transmission arrangement according to the invention is not subject to static overdetermination.

[0064] Embodiments of the invention will now be described by way of example and with reference to the accompanying drawings, in which:

[0065] Fig. 1 schematically shows an embodiment of the power transmission arrangement according to the invention;

[0066] Fig. 2 schematically shows another embodiment of the power transmission arrangement according to the invention; Fig. 3 schematically shows a rotor arrangement according to the invention;

[0067] Fig. 4 schematically shows an electrical machine according to the invention; and Fig. 5 shows a block diagram of the method according to the invention.

[0068] Before referring to the embodiments in the figures, general statements are made about the power transmission arrangement according to the invention.

[0069] In inductive power transmission, as in the power transmission arrangement described herein, an alternating current provided by the power electronics is transmitted contactlessly through an inductive (current / rotary) transmission device. Such an inductive transmission device can be a (e.g. rotationally symmetrical) transformer comprising a primary arrangement and a secondary arrangement, wherein the primary arrangement comprises a primary ferrite core with associated primary windings and the secondary arrangement comprises a secondary ferrite core with associated secondary windings. The primary winding (coil) generates a magnetic field which is bundled by the ferrite core(s). The primary ferrite core and the secondary ferrite core are separated from one another by an air gap. As a rule, the primary arrangement is arranged in a fixed location in the electrical machine, e.g. on the housing, and the secondary arrangement, on the other hand, is rotatable, e.g.through a non-rotatable connection with the rotor.

[0070] The inductive transmission device allows an alternating current to be transmitted contactlessly from the primary winding of the primary assembly to the secondary winding of the secondary assembly. A rectifier board connected to the secondary winding taps the transmitted alternating current and converts it into direct current to power the rotor winding.

[0071] The power transmission unit typically comprises a primary assembly and a secondary assembly that are rotatable relative to one another. Both the primary assembly and the secondary assembly each comprise a ferrite and a magnetic coil arranged around it. A design that has proven successful so far is one in which the cylindrical primary assembly is aligned axially within the cylindrical secondary assembly. The two magnetic coils are arranged overlapping between them. The primary assembly is firmly connected to the housing, and the secondary assembly is non-rotatably connected to the rotor. The circumferential air gap between the ferrite of the primary assembly and the ferrite of the secondary assembly forms the transmission surface and is crucial for efficient power transmission.

[0072] The air gap is formed at each end section, and the overlapping coils are arranged in the center section. The air gap should be as small as possible in the radial direction, for example, less than 1 mm. However, the air gap is limited downwards, taking into account tolerances and play. For the best possible efficiency, the primary and secondary arrangements must be aligned as precisely as possible in the axial direction.

[0073] Returning to the embodiments of the present invention, Fig. 1 shows an embodiment of the power transmission assembly (10) according to the invention. Fig. 1 depicts an embodiment of a pre-assembled bearing end (1). A primary ferrite (3a) of a primary assembly (3) of the power transmission assembly (10) is held in a pre-assembly position A by means of an internal assembly lock (2), which may be designed, for example, in the form of a flexible retaining ring.

[0074] According to one embodiment, the primary assembly (3) in Fig. 1 can be connected to a support lance (4), for example, by a clamping connection with a nut (5). The support lance (4) can, in turn, be held to the bearing end (1) with an external assembly lock (6), as also shown in Fig. 1.

[0075] Figure 2 shows an embodiment of a preassembled cylindrical hollow shaft (7) comprising the power transmission assembly (10). A securing element (8) is mounted on the inside and at an outer end of the cylindrical hollow shaft (7). The securing element (8), for example, fixes the rectifier unit (9) and the secondary assembly (11) inside the cylindrical hollow shaft (7).

[0076] In this way, the cylindrical hollow shaft (7) comprising the secondary arrangement (11) of the power transmission arrangement (10) according to the invention can be pre-assembled.

[0077] Figure 3 shows the rotor assembly (20) according to the invention in a pre-assembly position A. The bearing end (1) is connected to the cylindrical hollow shaft (7). The primary ferrite (3a) of the primary assembly (3) is located in the pre-assembly position A and is secured or fixed by the assembly locks (2, 6).

[0078] Fig. 4 shows an electric machine (30) according to the invention. The electric machine (30) of Fig. 4 has a rotor assembly (20), wherein the position of the primary assembly (3) of the power assembly (10) is in a functional position B. A functional position B here means, for example, maintaining a previously defined air gap and an axial positioning relative to the secondary assembly (11) installed in the cylindrical hollow shaft (7) of the power transmission assembly (10).

[0079] The cylindrical hollow shaft (7) is surrounded by a stator (22) with a laminated core and windings (21). The bearing end (1) is supported by a rotor bearing (23). The support lance (4) is connected to the housing (31) of the electric machine (30), for example, by a screw connection (32).

[0080] In Fig. 5, an overview diagram of the methods according to the invention for pre-assembly of a bearing end (1) for a power transmission arrangement (10), pre-assembly for a rotor arrangement (20) and assembly of an electrical machine (30) is shown in summary.

[0081] In step S1, a bearing end (1) is provided. The bearing end (1) is provided with a groove into which an inner assembly lock (2) is fitted. In step S2, a carrier lance (4) is connected to a primary assembly (3) comprising a primary ferrite (3a). In method step S3, the primary assembly (3) is fastened to the bearing end (1) in a pre-assembly position A via the primary ferrite (3a) through the inner assembly lock (2). In a further method step S4, the carrier lance (4) is fastened to an outer end of the bearing end (1) with an outer assembly lock (6) on the bearing end (1). Method steps S1 to S4 represent the method steps for pre-assembling the bearing end (1) of the power transmission assembly (10) according to the invention.

[0082] In a further method step S5, a cylindrical hollow shaft (7) is prepared. In a method step S6, a secondary unit (11) and a rectifier unit (9) are fixed in the cylindrical hollow shaft (7) by means of securing elements (8). Method steps S5 and S6 represent the method steps for pre-assembling the cylindrical hollow shaft (7).

[0083] In method step S7, the preassembled bearing end (1) comprising the primary assembly (3) is connected to the preassembled cylindrical hollow shaft (7) comprising the secondary assembly (11) in a preassembly position A. The connection can be a welded joint. Method step S7 represents the preassembly of the rotor assembly (20).

[0084] In method step S8, the rotor assembly from method step S7 is inserted into the rotor housing. In method step S9, the primary assembly is adjusted to a functional position B. The functional position B is, for example, a position in which a previously defined air gap is maintained between the primary assembly (3) and the secondary assembly (11). In this exemplary embodiment, the functional position is achieved by pushing the primary ferrite (3b) out of the inner assembly lock by means of the carrier lance (4) into the secondary assembly (11). The contactless guidance of the primary assembly into the functional position B is achieved by the outer assembly lock (6). The outer assembly lock (6) can optionally be removed after the functional position has been adjusted. In method step S10, the carrier lance (4) is fastened to the machine housing (31) of the electrical machine (30) by means of a closure element (32).

[0085] In this way, the primary assembly can be held fixed to the stator and does not require its own bearing, which saves costs and installation space.

[0086] In addition, the individual components of the rotor shaft can be pre-assembled, which can save time and effort during the final assembly of an electrical machine.

[0087] The process steps S1-S4 and S5-S6 shown as parallel in Fig. 5 can also be carried out one after the other.

[0088] Reference symbol

[0089] Bearing internal assembly lock

[0090] Primary arrangement a primary ferrite

[0091] Carrier lance

[0092] Nut external assembly lock cylindrical hollow shaft / rotor hollow shaft

[0093] securing element

[0094] Rectifier unit 0 Power transmission assembly 1 Secondary ferrite 0 Rotor assembly 1 Laminated core with windings 2 Stator 0 Electrical machine 1 Housing 2 Screw connection

Claims

Patent claims 1. Power transmission arrangement (10), in particular an inductive power transmission arrangement (10), for transmitting power to a rotor arrangement (20) of a separately excited electrical machine (30), comprising: - a carrier lance (4) connected to a primary assembly (3); - one bearing end (1 ), and - an internal assembly lock (2) which fixes the primary assembly (3) in the bearing end (1) in a pre-assembly position and remains therein after the assembly of the power transmission assembly (10).

2. Power transmission arrangement (10) according to claim 1, further comprising an outer mounting lock (6) which pre-assembles the support lance (4) in the bearing end (1).

3. Power transmission arrangement (10) according to claim 2, wherein the outer mounting lock (6) is removable from the bearing end (1).

4. Power transmission arrangement (10) according to one of the preceding claims, further comprising a hollow rotor shaft having a cylindrical part (7) with a secondary arrangement (11).

5. Power transmission arrangement (10) according to claim 4, wherein the cylindrical part (7) has an inner and an outer securing element (8).

6. A power transmission arrangement according to claim 4 or 5, wherein the cylindrical part (7) further comprises a rectifier unit (9) and a protection circuit.

7. A method for pre-assembling a bearing end (1) for the power transmission arrangement (10) according to one of claims 1 to 6, comprising: - Providing the bearing end (1 ); - connecting the carrier lance (4) to the primary assembly (3); - securing the primary assembly (3) inside the bearing end (1) with the internal assembly lock (2); and - Fasten the support lance (4) to an outer end of the bearing end (1) with the outer assembly lock (6).

8. A method for pre-assembling a rotor assembly (20), comprising: - Providing the bearing end (1) according to claim 7; - Providing the cylindrical part (7) of the hollow rotor shaft, comprising the secondary arrangement (11), the rectifier unit (9) and the protection circuit; and - Connecting the bearing end (1) to the cylindrical part (7) of the hollow rotor shaft.

9. A method for assembling an electrical machine (30), comprising: - providing the rotor assembly (20) according to claim 8; - inserting the rotor arrangement (20) into a housing (31) of the electrical machine (30); - pushing the support lance (4) out of the inner assembly securing device (2) of the bearing end (1) into the cylindrical part (7) of the hollow rotor shaft into a functional position, wherein the inner assembly securing device (2) remains in the bearing end (1); and - Fixing the support lance (4) to the housing (31) of the electrical machine (30).

10. A method for assembling an electrical machine (30) according to claim 9, further comprising: - Remove the outer assembly lock (6) at the outer end of the bearing end (1 ).

11. Motor vehicle comprising an electric machine (30) according to one of claims 9 and 10.

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