Power transmission arrangement for power transmission to a rotor arrangement of a separately excited electrical machine, method for assembling a power transmission arrangement, rotor arrangement with the power transmission arrangement and separately excited electrical machine with the rotor arrangement

Abstract

The present invention relates to a power transmission arrangement (10), in particular an inductive power transmission arrangement (10), for transmitting power to a rotor arrangement of a separately excited electrical machine (20), comprising a hollow rotor shaft (11), a primary arrangement (1), a support lance (3) which is connected to the primary arrangement (1) and a bearing arrangement (4) which supports the support lance (3), which is connected to the primary arrangement (1), in a cylindrical part of the hollow shaft (11).

Description

In the field of externally excited electric motors, power transmission arrangements play an increasingly important role as exciters, since permanent magnets or rare earths can thereby be dispensed with.In externally excited electric motors, the rotor magnetic field is generated by current flow through coils in the moving rotor. The transmission of the electrical energy from the stationary into the rotating system usually takes place conductively via slip rings in the case of drives which are widely used on the market.An alternative to conductive energy transmission is provided by externally excited electric motors, in which the energy transmission takes place inductively. As a result, both the permanent magnets and sliding contacts can be dispensed with.The current is transmitted to the rotor via an inductive transformer. The transformer is supplied with energy by the stator via an alternating voltage. The alternating voltage is converted on the rotor side into direct voltage via a rectifier for the magnet coils of the rotor. The magnet coils then induce a rotor magnetic field which interacts with the stator magnetic field. This allows the motor to generate torque. The magnet coils replace the permanent magnets. The system of inductive transformer and rectifier can also be referred to as inductive exciter.Electric motors are often subject to strict installation space requirements. The design of the inductive exciter is, however, limited, since all movable components in the exciter must have a very high rotational speed strength. The rotational speeds in the exciter can be in the range of 18,000 and 24,000 revolutions per minute.In exciters, the brittle material ferrite is often used for the cores of the magnet coils. In particular, this results in significant restrictions in the freedom of design with regard to the rotational speed strength.When using a primary ferrite and secondary ferrite for inductively exciting a synchronous motor, a defined air gap must frequently be set on the electric machine, by means of which air gap it can be ensured on the one hand that the ferrites do not touch one another, since damage can thereby occur. On the other hand, for high power ranges of an electric machine, it may be necessary to ensure a defined distance of the primary and secondary arrangements in order to be able to transmit the desired currents to the rotor.Furthermore, for the installation space-neutral integration of an inductively excited SESM rotor, for example into the system installation space of a permanently excited machine, an arrangement of the transformer, that is to say of the inductive exciter, within the hollow rotor shaft, which can be composed of a plurality of parts, is necessary. The rotor shaft consists of a central part and a side part which has the bearing seat for the rotor shaft. It may be desirable to maintain rotor support in terms of bearing type, bearing size, and bearing spacing, for example, to maintain modular compatibility with permanently excited rotors.In order to be able to ensure the required transmission line of the inductive currents, a specific 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 region below the laminated core of the stator.However, the inner diameters of the specified rotor bearings can be smaller than the inner diameter of the hollow shaft in the central region, which is why the transformer or the secondary side must be mounted in the rotor shaft before a multi-part rotor shaft can be joined together 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 the latter has a larger diameter in the region below the rotor bearing on the side on which the transformer is arranged than a possible inner diameter of the rotor shaft, or of a side part of the rotor shaft, which is, for example, a bearing end and tapers correspondingly.Accordingly, the stator-fixed, non-corotating primary side of the transformer must be inserted into the rotor before the latter is joined, finished working and completed, since it no longer fits through the lateral opening of the hollow shaft later.Furthermore, it must be ensured that the primary side of the inductive transformer is held reliably enough that it is not damaged or damage another part even during the manufacture of the motor, for example during insertion into the hollow rotor shaft. Moreover, it must be ensured that the primary side of the transformer is positioned sufficiently accurately with respect to the secondary side during operation in order to be able to maintain the defined air gap described above and to prevent primary and secondary ferrite from touching, since they can thus be damaged or the rotor bearing can thus be damaged.Previous arrangements and assembly methods are not able to hold the primary side firmly in terms of the stator before joining a bearing end or side part of a rotor shaft, or to position and fix the primary side generally with respect to the rotor-side components, such as the secondary side connected to the rotor in a rotationally fixed manner, as a result of which the primary side lies loosely in the hollow shaft and can thus be damaged. Fixed to the stator here means, for example, that the primary side of the transformer does not corotate.It is therefore an object of the present invention to provide a power transmission arrangement, a rotor arrangement and a separately excited electric machine, in which the disadvantages specified above are at least partially reduced.This object is achieved by a power transmission arrangement according to claim 1, a method for pre-assembly of a power transmission arrangement according to claim 7, a method for pre-assembly of a rotor arrangement according to claim 8, a method for assembly of a separately excited electric machine according to claim 9 and a motor vehicle according to claim 11.Further aspects and features of the present invention will become apparent from the dependent claims, the accompanying drawings and the following description of embodiments.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:a hollow rotor shaft;a primary arrangement;a support lance connected to the primary assembly; anda bearing arrangement which supports the carrier lance, which is connected to the primary arrangement, in a cylindrical part of the hollow shaft.The term "power transmission arrangement" describes an exciter of an electric machine. The power transmission arrangement generally serves to induce electrical energy from power electronics into the rotor winding. The power transmission arrangement may be an exciter, for example an inductive exciter, and is configured to transmit power to a rotor arrangement of a separately excited electric machine. The externally excited electric machine may be an electric motor.A hollow rotor shaft here means, for example, a cylindrically shaped part of a hollow shaft, which does not have a bearing end and into which the inductive transformer or the power transmission arrangement can be inserted.The power transmission arrangement according to the invention initially has a carrier lance which is connected to a primary arrangement. 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 carrier lance can furthermore be designed such that it has different diameters in longitudinal section regions.The length of the support lance can be dependent on the installation space length of the electric machine and / or the length of the primary arrangement. The support lance may be configured to be connected to a machine housing of the electric machine.The primary assembly may be connected to the support lance. For example, the primary arrangement can be fixed to the carrier lance by a securing ring. The retaining ring may be a nut. The connection can also be made by gluing, welding and the like. There may be more than one connection and / or type of connection between the primary arrangement and the carrier unit.The primary arrangement may be the primary side of an inductive transformer and may comprise a primary winding and a primary ferrite. The primary winding can be arranged rotationally fixedly around the primary ferrite. The primary ferrite may be cylindrical. The primary ferrite may have a T-shaped cross section.The power transmission arrangement according to the invention further comprises a bearing arrangement which is connected to the carrier lance. The bearing arrangement is configured, for example, such that an inner region of the bearing arrangement is connected to the carrier lance and an outer region is connected to an inner diameter of a section of the cylindrical part of the hollow rotor shaft. The connection can be effected directly, for example by adhesive bonding, but a further element can also be arranged between the inner diameter of the hollow shaft and the outer region of the bearing arrangement and can be connected to the latter in each case.In one exemplary embodiment, the bearing arrangement comprises two ball bearings set against one another. The bearing arrangement can be designed such that a prestressed O-arrangement is formed from the two ball bearings by a spacer disk being located between the segments of the outer region of the bearing arrangement or the outer rings of the ball bearings, while the inner region of the bearing arrangement or the inner rings of the ball bearings is / are connected to the carrier lance, wherein the inner rings are compressed under prestress. This can result in a particularly compact configuration and high bending stiffness of the bearing arrangement, for example. In this way, a pre-assembled bearing cartridge can be produced, for example by fitting the bearing arrangement into a sleeve.A preload bearing as described above has a higher tilting stability than a single ball bearing, whereby it can be ensured in this embodiment according to the invention that the primary assembly and the secondary assembly do not touch and thus can be prevented from being damaged. Furthermore, the bearing arrangement according to the invention can ensure high smoothness of running during operation.As already described above, in one embodiment the ball bearings are separated by a spacer disc which is mounted between the outer rings of the ball bearings. The spacer disk can contribute to increasing the bending stiffness of the bearing arrangement.In a further exemplary embodiment, the carrier lance is connected to an inner ring of the bearing arrangement.According to a further exemplary embodiment, the carrier lance can have a cutout for line guidance. The cutout can be configured, for example, by a groove or by a bore through which the connections and / or lines are led out.In a further embodiment, the power transmission arrangement may comprise a spring, wherein the spring is attached to the bearing arrangement. Depending on the embodiment of the bearing arrangement, the spring can be attached to an axially left or to an axially right end of the bearing arrangement.In a further embodiment, the power transmission assembly comprises a sleeve attached to the bearing assembly. The sleeve can, for example, space the bearing arrangement from the inner diameter of the hollow rotor shaft. Furthermore, the sleeve can be designed such that it spaces the bearing arrangement from the secondary arrangement. As a result, it is possible to use, for example, smaller bearings which are better suited for the construction of the rotor or the desired rotational speeds. Furthermore, the assembly of the power transmission arrangement can thus be facilitated. Furthermore, a pre-assembled bearing cartridge described further above can thus be obtained by fitting the pre-tensioned bearing arrangement into the sleeve described here.For example, the carrier lance can be inserted into a pre-assembled bearing cartridge which comprises the sleeve and the ball bearings. The pre-assembled bearing cartridge can be pre-assembled together with the primary ferrite core on the carrier lance. In this case, the inner rings according to one exemplary embodiment can be pressed against one another via a corrugated spring as a bearing spring between a securing ring and one of the inner rings and can thus be set elastically or prestressed in an O-arrangement.In a further embodiment, the carrier lance is pre-assembled with the primary arrangement and the bearing arrangement. This can be effected, for example, in a manner described above.In a further embodiment, the power transmission arrangement further comprises a secondary arrangement and a rectifier unit. The secondary arrangement may be the secondary side of the inductive transformer or the power transmission arrangement and may comprise a secondary winding and a secondary ferrite. The secondary arrangement can be cylindrical. The secondary assembly may have a U-shaped cross-section. The rectifier unit may be in contact with a protection circuit.In another aspect, the present invention provides methods of assembling a power transmission assembly comprising:providing a bearing end;providing the hollow shaft;providing the support lance, wherein the support lance is connected to the primary assembly and the bearing assembly;attaching a securing ring within the cylindrical part of the hollow shaft;attaching the rectifier unit to the securing ringattaching the secondary assembly to the rectifier unit;attaching the spring to the secondary assembly;attaching the provided support lance with primary arrangement and bearing arrangement to the spring;attaching a snap ring to an outer end of the cylindrical part of the hollow shaft; andjoining the hollow shaft to the bearing end, wherein one end of the carrier lance protrudes from the bearing end.Instead of a securing ring, a shoulder may also be present on an inner diameter of the hollow shaft as an axial stop.A bearing end is, for example, a side part of the hollow rotor shaft that is not, or not yet, provided.In a further aspect, the present invention provides a rotor arrangement comprising a power transmission arrangement according to the invention.By means of the power transmission arrangement according to the invention, all electronic components of a rotor arrangement, such as, for example, the rectifier unit of an inductively excited rotor and the primary arrangement and the secondary arrangement of the inductive transformer, can be pre-assembled in a cylindrical part of the hollow rotor shaft before the hollow rotor shaft is provided with a bearing end, which is, for example, funnel-shaped.The primary arrangement is mounted without play in the cylindrical part of the hollow rotor shaft by the bearing arrangement. In one embodiment of the present invention, the primary arrangement of the power transmission arrangement can be present as a pre-assembled component. The pre-assembled component can comprise a carrier lance which is connected to the primary arrangement and to a bearing arrangement.In a further aspect, the present invention provides an electric machine comprising the rotor arrangement according to the invention. The electric machine is, for example, a separately excited electric machine.When mounting the rotor arrangement in the housing of an electric machine, the carrier lance, which is connected to the primary arrangement, can be connected to the housing of the electric machine, for example, in a manner such that a defined, tangential relative movement of the carrier lance is permitted. The permitted relative movement is at a maximum + / -2 degrees.The permitted relative rotational movement of the carrier lance with respect to the housing of the electric machine can be achieved, for example, in that the carrier lance is not round at the housing end, but is, for example, semicircular and the housing has the corresponding negative contour, by means of which the carrier lance is fixed with little play. By allowing a slight play, a static over-certainty of the power transmission arrangement can be avoided.Since the power transmission arrangement according to the invention is mounted on the primary side (i.e. its primary arrangement) in the rotor shaft by means of the bearing arrangement, it is possible in principle to use any desired coupling known from the prior art for connecting the carrier lance to the machine housing, wherein the coupling method can allow compensation of axis offsets, angle errors and axial movements in order to avoid a rigid coupling to the machine housing and thus a static overdetermination.In one exemplary embodiment, the carrier lance of the power transmission arrangement can be incorporated in a potential compensation of the electric machine. Furthermore, the power transmission arrangement can have a sealant at the connection point to the electrical machine when it is installed in the system housing, and can also have the inclusion in the potential compensation. As a result, for example, a current flow in the bearing arrangement of the power transmission arrangement of the inductive exciter can be prevented.In a further aspect, the present invention comprises a vehicle which has the electric machine according to the invention.By means of a rotor arrangement according to the invention and the method presented here for mounting the power transmission arrangement for a rotor arrangement for an electric machine, it can be ensured that the primary side is held securely enough that it is not damaged during handling and the manufacturing processes between the insertion into the rotor shaft and the installation of the rotor into the housing, or that it damage another part.Furthermore, a rotor configured in this way and its mounting concept can ensure that the primary side of the transformer is positioned sufficiently accurately with respect to the secondary side during operation.Embodiments of the invention will now be described by way of example and with reference to the accompanying drawing, in which: FIG. 1 schematically shows an embodiment of the power transmission arrangement according to the invention; FIG. 2 schematically shows a further embodiment of the power transmission arrangement according to the invention; FIG. 3 schematically shows an electric machine according to the invention; FIG. 4 schematically shows a further embodiment of the power transmission arrangement according to the invention; and FIG. 5 shows a block diagram of the method according to the invention.Before referring to the embodiments in the figures, general explanations are made on the power transmission arrangement according to the invention.In inductive power transmission as in the power transmission arrangement described herein, an alternating current provided by the power electronics is transmitted in contactless fashion by an inductive (current / rotation) transmission device. Such an inductive transmission device may be a (e.g. rotationally symmetric) 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 each other by an air gap. As a rule, the primary arrangement is arranged in a spatially fixed manner in the electric machine, for example on the housing, and the secondary arrangement, on the other hand, is rotatable in, for example by a rotationally fixed connection to the rotor.By means of the inductive transmission device, an alternating current can be transmitted from the primary winding of the primary arrangement in a contactless manner to the secondary winding of the secondary arrangement. A rectifier board connected to the secondary winding extracts the transmitted alternating current and converts it into direct current for energizing the rotor winding.The power transmission unit usually comprises a primary arrangement and a secondary arrangement, which are rotatable relative to one another. Both the primary arrangement and the secondary arrangement each comprise a ferrite and a magnetic coil arranged around it. A design has been proven in this case in which the cylindrical primary arrangement is aligned in the axial direction within the cylindrical secondary arrangement. In between, the two magnet coils are arranged overlapping. The primary arrangement is firmly connected to the housing and the secondary arrangement is rotationally fixed to the rotor. The air gap running in the circumferential direction between the ferrite of the primary arrangement and the ferrite of the secondary arrangement forms the transmission surface and is decisive for efficient power transmission.The air gap is formed at the end portions, respectively, and the overlapping coils are disposed at the central portion. The air gap should be as small as possible in the radial direction, for example below 1 mm. However, the air gap is limited downward, taking into account tolerances and play. For the best possible efficiency, the primary arrangement and the secondary arrangement must be aligned as exactly as possible with respect to one another in the axial direction.Returning to the embodiments of the present invention, an exemplary embodiment of the power transmission arrangement ( 10) according to the invention is illustrated in FIG. 1. In the cylindrical part of a hollow rotor shaft (11), a securing ring (12) is attached at an outer end. A primary arrangement (1) is connected to a support lance (3). The connection can be made by clamping with a nut (5). The support lance ( 3) is furthermore connected to a bearing arrangement ( 4). The bearing arrangement in FIG. 1 consists of two ball bearings ( 4 a, 4 b) which form a prestressed O-arrangement as bearing region ( 6) for the support lance ( 3). In the bearing region ( 6), a spacer disk ( 7) can be located between the outer rings ( 41 a, 41 b) of the ball bearings ( 4 a, 4 b). The inner rings ( 42 a, 42 b) of the ball bearings ( 4 a, 4 b) are connected to the carrier lance ( 3) in a rotationally fixed manner, for example by adhesive bonding.The outer rings ( 41 a, 41 b) of the ball bearings ( 4 a, 4 b) can be connected to the inner wall of the cylindrical part of the hollow rotor shaft ( 11) in a rotationally fixed manner, for example by adhesive bonding. Alternatively, this can be achieved by a press fit between the mentioned parts.The components of the bearing region ( 6), in particular the inner rings ( 42 a, 42 b), can be bonded to the support lance ( 3) under prestress, which can result in a compact configuration of the bearing region which at the same time has a high bending stiffness. Alternatively, the inner rings ( 42 a, 42 b) can be axially clamped between, for example, an axial stop on the carrier lance ( 3) and a securing ring ( 26) by means of a bearing spring ( 27) and in the process can be acted upon by the spring force as a prestress.The power transmission assembly (10) of Figure 1 further comprises a spring (8) mounted between the second ball bearing (4b) and the secondary assembly (2). The spring (8) is located between the outer ring (41b) of the ball bearing (4b) and the secondary ferrite (2a) of the secondary arrangement (2). The spring ( 8) is configured, for example, to compensate component tolerances in the axial direction. In the exemplary embodiment of FIG. 1, the secondary arrangement ( 2) is followed by a rectifier unit ( 9). By means of a further securing ring ( 12), the components of the power transmission arrangement ( 10) described in the embodiment of FIG. 1 are fixed in the cylindrical part of the hollow rotor shaft ( 11).FIG. 1 also shows a bore ( 13) on the support lance ( 3), with which bore the support lance ( 3) is provided for line guidance.The embodiment of the power transmission arrangement ( 10) depicted in FIG. 2 is connected to a bearing end ( 14) of the hollow rotor shaft in addition to the embodiment depicted in FIG. 1. The connection may be a welded connection.The support lance ( 3) in FIG. 2 is designed such that it protrudes from the bearing end ( 14). The protruding end of the carrier lance ( 3) is provided with a protective cap ( 15) for protection against damage during further manufacturing steps, which protective cap can protrude into the interior of the bearing end ( 14). There are also embodiments, not shown, in which the protective cap (15) projects beyond the end of the bearing end (14).FIG. 3 shows an electric machine ( 20) according to the invention, in which the power transmission arrangement ( 10) is installed. The cylindrical part of the hollow rotor shaft (11) is surrounded by a stator (16) and the stator-side laminated core with winding (17). The rotor arrangement with the power transmission arrangement (10) is mounted in the housing (18) of the electric machine (20) by the rotor bearing (19). The housing (18) of the electric machine (20) has an opening (21) through which the carrier lance (3) is guided. The opening ( 21) can be a negative contour of the carrier lance ( 3). The support lance ( 3) can have a semicircular shape. The opening is provided with a seal (22). The housing (18) has a line opening (23) through which the lines of the power transmission arrangement (10) are guided. The carrier lance ( 3) and the housing ( 18) are incorporated into a potential compensation ( 24).FIG. 4 shows a further embodiment of the power transmission arrangement ( 10) according to the invention. Here, the primary arrangement ( 1) is pre-assembled together with the bearing arrangement ( 4) on the support lance ( 3) before it is mounted in the hollow rotor shaft ( 11). In this case, a sleeve ( 25) is attached to the bearing arrangement ( 4), which sleeve is bonded, for example, to the outer rings ( 41 a, 41 b) of the bearing arrangement. On the side of the bearing arrangement (4) on which the primary arrangement is located, the sleeve (25) has a projection which partially encloses the outer ring (41b). Thus, for the purpose of spacing and compensating for tolerances of the bearing arrangement (4) with respect to the secondary ferrite (2b), the spring (8) can be dispensed with.In the embodiment shown here, a securing ring ( 26) is furthermore attached to the carrier lance. Between the securing ring (26) and the inner ring (42a), a bearing spring (27) is mounted for tolerance compensation and for elastic positioning of the two bearings in an O-arrangement.If the power transmission arrangement ( 10) shown in FIG. 4 is installed in a hollow rotor shaft ( 11), then the spring ( 8) is located on the bearing arrangement ( 4) (not shown) on the side of the bearing end ( 14).FIG. 5 shows the method according to the invention for assembling the power transmission arrangement ( 10) in the form of a block diagram.The method according to the invention can be characterized in that all components of the power transmission arrangement are mounted in the cylindrical part of the hollow shaft (11) before it is provided with a bearing end (14).In the method according to the invention, in step S 1, first the support lance ( 3) is connected to the primary arrangement ( 1) and the bearing arrangement ( 4). In a further step S 2, a hollow rotor shaft ( 11) or its cylindrical part is provided. A retaining ring ( 12) is mounted therein at an inner central portion (S 3). The rectifier unit is attached to the securing ring ( 12) before the secondary arrangement ( 2) is inserted into the hollow shaft in method step S 4. The carrier lance ( 3) from method step S 1 is attached (S 5) to the secondary arrangement ( 2), wherein a spring ( 8) is attached to the bearing arrangement ( 4), for example between the bearing arrangement ( 4) and the secondary arrangement, in order to protect the primary arrangement from being interfered with by the secondary arrangement ( 2), or to space it from the bearing arrangement with installation space tolerance. In method step S 6, the components in the hollow rotor shaft ( 11) are fastened to an outer end of the cylindrical part by means of a further securing ring ( 12). In method step S 8, the hollow rotor shaft from method step S 6 is provided with the bearing end ( 14) provided in S 7, for example by welding.Reference numerals denote reference numerals1 Primary arrangement 2 Secondary arrangement 2 aSecondary ferrite 3 Carrier lance 4 Bearing arrangement 4 a, 4 b Kugellager bearing 5 Nut 6 Bearing region 7 Spacer plate 8 Spring 9 Rectifier unit 10 Power transmission arrangement 11 Hollow rotor shaft (cylindrical part) 12 Securing ring 13 Groove 14 Bearing end 15 Protective cap 16 Stator 17 Stator-side laminated core with winding 18 Housing 19 Rotor bearing 20 Electric machine 21 Opening 22 Seal 23 Line opening 24 Potential compensation 25 Sleeve 26 Securing ring 27 Bearing spring 41 a, 41 b Außenring ring ball bearing 42 a, 42 b Ring bearing

Claims

Power transmission arrangement (10), in particular an inductive power transmission arrangement (10), for power transmission to a rotor arrangement of a separately excited electric machine (20), comprising: - a hollow rotor shaft (11); - a primary arrangement (1); - a carrier lance (3) which is connected to the primary arrangement (1); and - a bearing arrangement (4) which supports the carrier lance (3) which is connected to the primary arrangement (1) in a cylindrical part of the hollow shaft (11).Power transmission arrangement (10) according to claim 1, wherein the bearing arrangement (4) comprises two ball bearings (4a, 4b) set against one another.The power transmission assembly (10) according to claim 2, wherein the ball bearings (4a, 4b) are separated by a shim (7) attached to an outer ring (41a, 41b) of the ball bearings (4a, 4b).Power transmission arrangement (10) according to one of the preceding claims, wherein the carrier lance (3) is connected to an inner ring (42a, 42b) of the bearing arrangement (4).Power transmission arrangement (10) according to one of the preceding claims, wherein the carrier lance (3) has a bore or cutout (13) for line guidance.The power transmission assembly (10) of any preceding claim, further comprising a spring (8), wherein the spring (8) is attached to the bearing assembly (4).The power transmission assembly (10) of any preceding claim, further comprising a sleeve (25) attached to the bearing assembly (4).Power transmission arrangement (10) according to one of the preceding claims, wherein the carrier lance (3) is pre-assembled with the primary arrangement (1) and the bearing arrangement (4).The power transmission arrangement (10) according to any of the preceding claims, further comprising: - a secondary arrangement (2); and - a rectifier unit (9).A method for assembling a power transmission assembly (10) according to any of claims 1 to 9, comprising: - providing a bearing end; - providing the hollow shaft; - providing the support lance, wherein the support lance is connected to the primary assembly and the bearing assembly; - attaching a circlip within the cylindrical part of the hollow shaft; - attaching the rectifier unit to the circlip; - attaching the secondary assembly to the rectifier unit; - attaching the spring to the secondary assembly; - attaching the provided support lance with primary assembly and bearing assembly to the spring; - attaching a circlip to an outer end of the cylindrical part of the hollow shaft; and - joining the hollow shaft to the bearing end, wherein an end of the support lance protrudes from the bearing end.A rotor comprising a power transmission assembly (10) according to any preceding claim.An electric machine (20) comprising the rotor of claim 11.Electric machine (20) according to Claim 12, wherein the carrier lance (3) is incorporated into the potential compensation (24) of the electric machine (20).Vehicle comprising the electric machine (20) according to any of claims 12 and 13.

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