Rotor assembly for an externally excited synchronous machine

Abstract

The present invention relates to a rotor assembly (100) for an externally excited synchronous machine. The rotor assembly (100) comprises: a rotor shaft (1) in the form of a hollow shaft for an excitation winding; a transmission unit (3) for contactlessly transmitting a current required for generating a rotor field to the excitation winding, the transmission unit (3) being arranged in the rotor shaft (1); and a hollow cooling body (9) which is arranged in the rotor shaft (1) and is designed to convey a cooling medium in the direction of an end face of the transmission unit (3), the cooling body (9) comprising a rectifier unit (11a) for the transmitted current on an outer surface. The invention also relates to an externally excited synchronous machine.

Description

[0001] Rotor arrangement for a separately excited synchronous machine

[0002] The present invention relates to a rotor arrangement for a separately excited synchronous machine.

[0003] Separately excited synchronous machines can be used in motor vehicles as drive devices and, unlike permanent magnet synchronous machines, comprise a rotor-side excitation winding (rotor winding) which can be energized to generate an excitation field which interacts with a stator field to generate a rotary movement of the rotor.

[0004] It is known from the prior art that an alternating current provided by the power electronics can be transmitted contactlessly by an inductive (current / rotation) transmission device. Such an inductive transmission device can be a (e.g. rotationally symmetrical) transformer comprising a primary unit and a secondary unit, wherein the primary unit comprises a primary ferrite core with an associated primary winding and the secondary unit comprises a secondary ferrite core with an associated secondary winding. The primary ferrite core and the secondary ferrite core are separated from one another by an air gap and are designed to be rotatable relative to one another. As a rule, the primary unit is arranged spatially fixed in the electrical machine, e.g. on the housing, while the secondary unit is rotatable, e.g. through a rotationally fixed connection to the rotor.

[0005] The inductive transmission device allows an alternating current to be transmitted contactlessly from the primary winding of the primary unit to the secondary winding of the secondary unit. A rectifier unit connected to the secondary winding taps the transmitted alternating current and converts it into a direct current to power the rotor windings.

[0006] Previous cooling concepts have insufficient cooling performance for components of the rectifier unit and the transmission device. The object of the present invention is to improve the cooling of components of the rectifier unit and / or the inductive transmission device.

[0007] The object is achieved by a rotor arrangement according to claim 1 and a separately excited synchronous machine according to claim 9.

[0008] A first aspect of the invention relates to a rotor arrangement for a separately excited synchronous machine, comprising:

[0009] - a rotor shaft designed as a hollow shaft for an excitation winding;

[0010] - an inductive transmission unit for the contactless transmission of a current required for rotor field generation to the excitation winding, wherein the transmission unit is arranged in the rotor shaft; and

[0011] - a hollow heat sink arranged in the rotor shaft and configured to convey a cooling medium toward an end face of the transmission unit, wherein the heat sink comprises a rectifier unit for the transmitted current on an outer surface, in particular an outer peripheral surface.

[0012] The rotor shaft carries the excitation winding. The excitation winding (rotor winding) can be energized to generate the rotor-side magnetic field (rotor field). The rotor field then interacts with a stator-side magnetic field (stator field), driving the rotor shaft and thus the rotor assembly.

[0013] The inductive transfer unit is designed to transfer the current for rotor field generation to the rotor winding. For this purpose, the transfer unit comprises a stator-side primary side, which includes a primary ferrite core with a primary-side winding (primary winding), and a rotor-side secondary side, which includes a secondary ferrite core with a secondary-side winding (secondary winding). The primary side is fixed to the stator, and the secondary side is connected to the rotor shaft in a rotationally fixed manner. The primary side and the secondary side are separated from one another by an air gap through which the cooling medium for cooling the transfer unit can flow. The transfer unit is arranged at one end of the rotor shaft and is at least partially inserted into the rotor shaft. In some examples, the transfer unit is arranged entirely within the rotor shaft. The end of the rotor shaft with the transfer unit is referred to as the drive-side end.Opposite this is an output-side end of the rotor shaft.

[0014] The heat sink is hollow and elongated and conducts the cooling medium in a direction from the output-side end of the rotor shaft to the transmission device. The heat sink comprises a cavity for transmitting the cooling medium, e.g., a fluid line that extends over the entire length of the heat sink, e.g., axially. In a cross-sectional view (in the direction of the longitudinal axis of the heat sink), the fluid line is arranged centrally. In some examples, the fluid line can be drilled. In other examples, the heat sink can be cast with a core for the fluid line to form the fluid line.

[0015] The heat sink is arranged at least partially in the rotor shaft and is located within the rotor shaft such that the fluid line is arranged coaxially to the rotation axis of the rotor shaft.

[0016] The rectifier unit for rectifying and transmitting the current from the secondary winding of the transfer unit to the rotor winding is located on the outer surface of the heat sink. Additionally, other components (of an electronic circuit) can be located next to the rectifier unit on the outer surface of the heat sink. These components include, for example, conductive tracks, contact elements (e.g., connectors for connecting the secondary winding of the transfer unit and the rotor winding to the rectifier unit), circuits (e.g., for smoothing the input current, rectifier circuit), components for limiting induced voltage peaks (e.g., varistors, suppressor diodes (TVS diodes)), and other active and / or passive components for implementing safety functions or transmitting signals.

[0017] In some examples, the rectifier unit is arranged on an outer peripheral surface of the heat sink (possibly distributed). The outer peripheral surface is a surface of the heat sink that faces radially outward (as viewed from the longitudinal axis of the heat sink).

[0018] By providing the rectifier unit directly on an outer surface of the heat sink, improved cooling of the rectifier unit can be achieved.

[0019] In some embodiments, the heat sink can have a multi-layer structure, wherein the multi-layer structure comprises a dielectric layer, a conductor layer, and an insulating layer, in particular a solder resist layer. This means that in a cross-sectional view of the heat sink (from inside to outside), the dielectric layer, the conductor layer, and the insulating layer are shown. The layered structure can be realized, for example, by producing an insulated metal substrate (also known as IMS), in which the dielectric layer and the conductor layer (e.g., a copper layer) are applied to a metallic base body (e.g., made of aluminum) of the heat sink by pressing under the influence of temperature.

[0020] In some examples, the dielectric layer may have a thickness of 50 to 200 μm and / or the conductive layer may have a thickness of 20 to 200 μm. The solder resist layer may, for example, have a thickness of 10 to 100 μm.

[0021] The conductor tracks in the conductor track layer can be made of copper, for example.

[0022] In some examples, the multilayer structure may also be present multiple times. This means that the multilayer structure can be present multiple times on top of each other to create a multilayer printed circuit board with multiple layers of conductor tracks (i.e., multiple levels of copper traces).

[0023] In some embodiments, the outer surface of the heat sink can be planar. This allows the rectifier unit to be applied to the heat sink particularly easily. In some examples, the heat sink can also have multiple planar outer surfaces. For example, the heat sink can be substantially cuboid-shaped and thus have four planar outer peripheral surfaces on which electronic components and / or contact elements can be applied.

[0024] In some embodiments, the rotor assembly may further comprise an intermediate element arranged between the transfer unit and the heat sink. The intermediate element comprises:

[0025] - an annular disc; and

[0026] - a receiving sleeve connected at one end to an inner edge of the annular disc.

[0027] The intermediate element can, for example, be formed from an insulating plastic and be substantially rotationally symmetrical. The annular disc comprises an inner hole defined by the inner edge of the annular disc. The receiving sleeve can be cylindrical. The receiving sleeve is connected to the inner edge at one end. The receiving sleeve is further connected to the annular disc such that an inner circumference of the receiving sleeve and the inner hole are aligned with each other.

[0028] The intermediate element can be arranged in the rotor shaft coaxially to the longitudinal axis of the rotor shaft and between the transmission unit and the heat sink.

[0029] The intermediate element's receiving sleeve accommodates the heat sink when the rotor assembly is assembled. This means that the receiving sleeve and the heat sink axially overlap.

[0030] The intermediate element can comprise contact elements that transmit the current from the transfer unit to the rectifier unit. For this purpose, the secondary winding of the transfer unit is connected to the intermediate element-side contact element, which is arranged on a side of the intermediate element facing the heat sink. The intermediate element-side contact element is connected to a correspondingly designed contact element of the rectifier unit, which is arranged on the heat sink.

[0031] In some embodiments, a free end of the receiving sleeve may include a radially inwardly projecting collar. The free end of the receiving sleeve is opposite the end of the receiving sleeve connected to the annular disc.

[0032] The collar extends radially inward from the free end relative to the longitudinal axis of the receiving sleeve. In some examples, the collar extends perpendicular to the longitudinal axis of the receiving sleeve.

[0033] As mentioned above, the receiving sleeve accommodates the heat sink. For this purpose, the collar in this embodiment has a collar opening.

[0034] In some embodiments, the receiving sleeve and the collar can define a collecting area for the cooling medium. The cooling medium, which is directed from the heat sink toward the transfer unit, is collected in the collecting area. Starting from the collecting area, the cooling medium can flow through the air gap of the transfer unit, which is located between the primary unit and the secondary unit, and thus cool the transfer unit. The collecting area can ensure that a minimum amount of cooling medium can flow through the air gap of the transfer unit.

[0035] In some embodiments, the heat sink can have a hollow nozzle that projects into the receiving sleeve and through the collar opening. The intermediate element and the hollow nozzle thus overlap or cover each other in the axial direction. The hollow nozzle is fluidly connected to the fluid line of the heat sink. The hollow nozzle enables targeted conveying of the cooling medium into the receiving sleeve and in particular into the collecting area. Furthermore, the accommodation of the hollow nozzle in the collar opening also enables positioning of the heat sink relative to the intermediate element. In some embodiments, a gap can be provided between the collar and the heat sink, in particular the hollow nozzle, for guiding the cooling medium from the receiving sleeve radially outwards towards an inner wall of the rotor shaft.

[0036] The collar and the heat sink or its hollow socket are designed such that, when the rotor assembly is assembled, a gap exists between the collar and the outer peripheral surface of the heat sink or the hollow socket. The cooling medium can flow radially outward from the receiving sleeve or the collecting area through this gap toward the inner wall of the hollow shaft. The gap thus enables cooling of the rotor shaft.

[0037] In some embodiments, the rotor arrangement can further comprise a cylindrical fixing element, via which the heat sink can be connected to the rotor shaft in a rotationally fixed manner. For this purpose, the fixing element can be arranged in the radial direction of the rotor arrangement between the heat sink and the rotor shaft and at least partially accommodate the heat sink axially. To accommodate the heat sink, the fixing element comprises an elongated recess. The fixing element can electrically insulate the rectifier unit of the heat sink from the rotor shaft. An outer diameter of the fixing element can be dimensioned such that the fixing element can be pressed into the hollow rotor shaft. Alternatively or in addition to the press fit, an anti-twist device can also be provided for the fixing element, for example by means of a tongue and groove connection between the inner side of the rotor shaft and an outer side of the fixing element.The fixing element thus enables positioning and fixing of the heat sink in the rotor shaft.

[0038] In some embodiments, the fixing element can have a form-fitting section for receiving the heat sink and for the form-fitting connection of the heat sink in the radial direction. The form-fitting section enables a form-fitting connection in the radial direction of the rotor arrangement and can be formed in the above-mentioned recess of the fixing element. In some examples in which the heat sink is cuboid-shaped, the recess in the region of the form-fitting section (seen in a cross-sectional view perpendicular to the longitudinal direction) can have a rectangular inner contour that corresponds to the outer contour of the heat sink. In the assembled state, the heat sink is thus firmly arranged in the fixing element at least in the radial direction and in the circumferential direction of the rotor shaft. Other form-fitting connection forms are also possible, e.g., a tongue and groove connection between the fixing element and the heat sink.

[0039] In some embodiments, the fixing element can comprise a support section for supporting the rectifier unit against centrifugal force. The support section can be provided in the above-mentioned recess of the fixing element and thus corresponds to an inner wall of the fixing element. The recess is dimensioned in the region of the support section such that the rectifier unit is supported in the radial direction of the rotor arrangement (and thus of the fixing element) by the inner wall of the recess. In other words, the support section encompasses the rectifier unit. In other examples, in which, in addition to the rectifier unit, further electronic components are provided on the heat sink, these can also be supported against centrifugal force by further corresponding support sections.

[0040] In some embodiments, the fixing element can comprise an axially extending groove on an outer circumferential surface. The groove serves as a fluid channel for guiding the cooling medium through the rotor shaft and extends from one end face of the fixing element facing the transmission unit toward the other end face. The cooling medium can be guided outward through the groove to a radial through-bore in the rotor shaft and from there toward the rotor winding. Furthermore, the cooling medium can be guided along the inner wall of the rotor shaft by means of the groove, thus cooling it.

[0041] A second aspect of the invention relates to a separately excited synchronous machine with a rotor arrangement according to one of the embodiments described above. The separately excited synchronous machine can be used as a drive motor for a motor vehicle. Embodiments of the invention will now be described by way of example and with reference to the accompanying drawings. In the drawings:

[0042] Fig. 1a schematically shows a rotor arrangement according to a first embodiment;

[0043] Fig. 1 b schematically shows an enlarged section in the rotor arrangement according to Fig. 1a;

[0044] Fig. 2 is a perspective view of a heat sink of the rotor assembly;

[0045] Fig. 3 is a cross-sectional view of the heat sink;

[0046] Fig. 4 schematically shows a cooling medium flow through the rotor arrangement of Fig. 1a;

[0047] Fig. 5a schematically shows a rotor arrangement according to a second embodiment;

[0048] Fig. 5b, c perspective views of the rotor arrangement according to the second embodiment; and

[0049] Fig. 6 schematically shows a cooling medium flow through the rotor arrangement of Fig. 5a.

[0050] Fig. 1 shows a rotor assembly 100 according to a first embodiment for a separately excited synchronous machine. The rotor assembly 100 comprises a rotor shaft 1 designed as a hollow shaft, an inductive transmission unit 3 for contactless transmission of current to a rotor winding (not shown), and a heat sink 9 for conducting a cooling medium.

[0051] The transmission unit 3 is arranged within the rotor shaft 1 and comprises a primary side 5 with a primary ferrite core 5a and a primary winding 5b. The primary ferrite core 5a is rotationally symmetrical and is plugged onto a pin 201 of a stator (not shown), thus firmly connecting it to the stator. In the present case, the primary ferrite core 5a comprises an axial (sleeve-shaped) section and a radially outwardly projecting section. The primary winding 5b at least partially wraps around the primary ferrite core 5a at its axial section. Furthermore, the transmission unit 3 comprises a secondary side 7 with a secondary ferrite core 7a and a secondary winding 7b. The secondary ferrite core 7a comprises an axial (sleeve-shaped) section and a radially inwardly projecting section. The secondary winding 7b is inserted into the secondary ferrite core 7a.The secondary ferrite core 7a is rotationally fixed to the rotor shaft 1 and thus rotatable relative to the primary ferrite core 5a. For example, the secondary ferrite core 7a can be rotationally fixedly coupled to an inner circumferential surface of the rotor shaft 1 along its axial section.

[0052] The primary winding 5b and the secondary winding 7b are framed by the axial and radial sections of the primary ferrite core 5a and the secondary ferrite core 7a and at least partially overlap axially (as viewed in the longitudinal direction of the rotor assembly 100 or rotor shaft 1). In other embodiments (not shown), the primary windings 5a and the secondary windings 7b can also completely overlap axially.

[0053] The heat sink 9 is elongated and arranged in the rotor shaft 1 and coaxially to its longitudinal axis. The heat sink 9 is connected to the rotor shaft 1 in a rotationally fixed manner (e.g., via a fixing element 15 described later). A hollow connecting piece 9a is provided at an end of the heat sink 9 facing the transmission unit 3. The heat sink 9 further comprises a fluid line 9b that extends over the entire length of the heat sink 9. The fluid line 9b is arranged centrally in the heat sink 9 (in a cross-sectional view of the heat sink 9) and is designed such that, when the rotor assembly 100 is in the assembled state, it runs coaxially to the longitudinal axis of the rotor shaft 1. This enables the cooling medium to be guided close to the axis of rotation. Furthermore, the heat sink 9 comprises, at an end facing away from the transmission unit 3, a (heat sink side) radially inwardly projecting collar 9c through which a stator-fixed cooling medium supply line 203 projects.The cooling medium is supplied to the heat sink on the stator side via the cooling medium supply line 203. There is an axial overlap between the heat sink 9 and the cooling medium supply line 203. The heat sink 9 can be plugged onto the cooling medium supply line 9 and positioned using the heat sink-side collar 9c. Furthermore, a seal (not shown) can be provided in the area of ​​the heat sink-side collar 9c between the heat sink 9 and the cooling medium supply line 203.

[0054] Fig. 2 shows a perspective view of the heat sink 9. The heat sink 9 is essentially cuboid-shaped and comprises an electronic circuit 11 on a first (upper) outer circumferential surface. The electronic circuit 11 comprises a rectifier unit 11a, which is connected via a male contact element 11b to the output of the secondary winding 7b of the transmission unit 1 and via a first female contact element 11c to an input of the rotor winding (not shown). The male contact element 11b and the first female contact element 11c are each present in pairs in order to contact both electrical poles of the secondary winding 7b and the rotor winding, respectively. The male contact element 11b is L-shaped in Fig. 1a. In other examples, a different shape may also be possible. As can also be seen from Fig.1a, a second electronic circuit 11 is present on a second outer circumferential surface, which lies opposite the first outer circumferential surface. In other examples, the electronic circuits 11 can also be distributed over other outer surfaces. Furthermore, the electronic circuits 11 can comprise at least one of the following components and / or contact elements, such as components for limiting induced voltage peaks (varistors, TVS diodes), active or passive components for implementing safety functions or for transmitting signals, and a circuit for smoothing the input current (e.g., an RC snubber). By providing the electronic circuits 11 on the heat sink 9, the electronic circuits 11 can be particularly effectively cooled.

[0055] Fig. 3 shows a schematic cross-sectional view of the heat sink 9 along the line AA shown in Fig. 1. The heat sink comprises a base body 91 which is made of a thermally conductive material, e.g. metal. In one example, the base body 91 is made of aluminum. On the sides with the electronic circuits 11, the heat sink 9 comprises a dielectric layer 92 as an insulating layer, which can have a thickness of 50 μm to 200 μm, for example, and a conductor track layer 93, which can be made of copper, for example, and / or have a thickness of 20 μm to 200 μm. Finally, a solder resist layer 94 can be provided which has a thickness of 10 μm to 100 μm. In some examples, the layer structure can be provided only in a partial area of ​​the side, e.g. in the area of ​​the electronic circuits 11. In other examples, the layer structure can extend over the entire side.In further examples, the layer structure comprising the dielectric layer 92 and the conductor layer 93 can also be present, at least in part, multiple times one above the other to create a multilayer printed circuit board. If printed circuit board arrangements, such as the electrical circuits 11, are provided on several outer surfaces of the heat sink 9, these can be electrically connected to one another using additional conductor layers 93.

[0056] In principle, the layered structure and thus the arrangement of the electronic circuits 11 can be present on only one or more sides of the heat sink 9. It is also possible for the electronic circuits 11 to be distributed on all sides of the heat sink 9, so that the layered structure is also present on all sides.

[0057] A manufacturing process for the heat sink 9 can be carried out in accordance with known processes for metal-core printed circuit boards (e.g., IMS printed circuit boards). For example, a dielectric and a copper layer are applied to the metal core by pressing under the influence of heat.

[0058] In order to provide the required electrical insulation (air and creepage distances) between the electronic components and contact elements of the electronic circuits 11, a further solder resist layer 94a or another coating with a different electrical insulator can optionally also be present on further intermediate regions between the elements of the electronic circuit 11 on the heat sink 9. In some examples, the further solder resist layer 94a can also be formed integrally with the solder resist layer 94.

[0059] If, for example, the electrical circuits 11 are placed only on an outer surface of the heat sink 9 or if the conductor tracks or the conductor track layers 93 occupy only a part of the outer surface of the heat sink 9, it may be necessary to provide the additional solder resist layer 94a on the surfaces on which no circuits or conductor tracks are placed in order to insulate the conductive heat sink 9 from the current-carrying elements of the electronic circuits 11.

[0060] Referring again to Fig. 1a, the rotor assembly 100 further comprises an intermediate element 13, which is arranged axially between the transmission unit 3 and the heat sink 9. The intermediate element 13 enables the cooling medium to be guided in the region of the rotor shaft 1, in particular in an area on the side of the transmission unit 3, as will be described later with reference to Fig. 4. During assembly of the rotor assembly 100, the heat sink 9 with the electronic circuit 11 is inserted axially from the drive side (from the left) into the rotor shaft 1, followed by the transmission unit 3 with the intermediate element 13.

[0061] The intermediate element 13 is formed from a plastic material, for example, an electrically insulating one. The intermediate element 13 comprises an annular disc 13a as a base and a receiving sleeve 13b, which extends away from the annular disc 13a and is arranged coaxially with the annular disc 13a. An inner hole 13e of the annular disc 13a is aligned with the inner circumference of the receiving sleeve 13b. Thus, an edge of the inner hole 13e and an end of the receiving sleeve 13b are connected to each other. At another (free) end, the receiving sleeve 13b comprises a radially inwardly projecting collar 13c. The collar 13c forms a collar opening 13d for receiving the hollow socket 9a of the heat sink 9.

[0062] On a side facing away from the transmission unit 3, the annular disc 13a has a second female contact element 13g for receiving the male contact element 11b. The second female contact element 13g is connected to the output of the secondary winding 7b. This allows the current transmitted by the transmission unit 3 to be passed on to the rotor winding via the female contact element 13g, the male contact element 11b, the rectifier unit 11, and the first female contact element 11c. The intermediate element 13 has an outer diameter at its base (annular disc 13a) that essentially corresponds to the inner diameter of the rotor shaft 1. The intermediate element 13 abuts axially with one side of the annular disc 13 against the transmission unit 3.Furthermore, the receiving sleeve 13b, the collar 13c, and an end face of the transfer unit 13 facing the intermediate element 13 define a collection area 13f for the cooling medium provided via the heat sink 9. The collar 13d ensures that a minimum amount of cooling medium flows through an air gap in the transfer unit 3. The collar 13c or the collar opening 13d is dimensioned such that a gap exists between the hollow socket 9a and the inner edge of the collar opening 13d, through which gap the cooling medium can flow from the collection area 13f toward an inner wall of the rotor shaft 1.

[0063] The rotor shaft 1 comprises radial through-bores 1a for guiding the cooling medium from an interior of the rotor shaft 1 to the outside to the rotor windings. Figs. 1a and 1b show two radial through-bores 1a arranged diametrically opposite one another. Alternatively, the radial through-bores 1a can also be distributed differently in the circumferential direction. In other examples, only a single radial through-bore 1a can be provided. In further examples, a plurality of radial through-bores 1a can be arranged (uniformly) distributed in the circumferential direction of the rotor shaft. A distribution of the radial through-bores 1a in the axial direction is also possible.

[0064] Fig. 4 schematically shows a cooling medium flow, indicated by arrows, in the rotor assembly 100 of Fig. 1a. At a first transfer point on the output side of the rotor shaft 1 (on the right side in Fig. 3), the cooling medium is transferred from the stator-side cooling medium supply line 203 to the heat sink 9 (which rotates with the rotor shaft 1 during operation), in particular into the fluid line 9b. At a second transfer point, which is located on the side of the transmission unit 3, the cooling medium flows into the collecting area 13f. From there, the cooling medium flows via the air gap between the primary ferrite core 5a and the secondary ferrite core 7a to the primary winding 5b and the secondary winding 7b and then to a side opposite the output side of the rotor assembly 100 (to the left in Fig. 3).Furthermore, due to the rotation generated during operation of the separately excited synchronous machine, the cooling medium flows through the gap between the collar 13c and the heat sink 9 toward the inner wall of the rotor shaft 1. Thus, the cooling medium flows around an outer side of the heat sink 9. Furthermore, the cooling medium flows through the radial through-bores 1a toward the rotor winding (not shown).

[0065] Fig. 5a-c schematically show sectional views of a rotor arrangement 100' according to a second embodiment. Fig. 5b and 5c show perspective sectional views, wherein the view of the rotor arrangement 100' from Fig. 5b is rotated approximately 90° about the longitudinal axis compared to the view from Fig. 5c. The rotor arrangement 100' according to the second embodiment differs from the rotor arrangement 100 according to the first embodiment by the heat sink 9, which, according to the second embodiment, has a funnel-shaped opening 9c at its output-side end instead of a collar. In the rotor arrangement 100' according to the second embodiment, the radial through-bores 1a are also present, but are hidden in Fig. 5a-c. Furthermore, the rotor arrangement 100' according to the second embodiment comprises a fixing element (further intermediate element) 15 for the heat sink 9.The fixing element 15 is cylindrical and is constructed substantially symmetrically with respect to a plane which is perpendicular to the plane of the drawing of Fig. 6 (described later) and which includes the longitudinal axis of the fixing element 15.

[0066] The fixing element 15 is formed from a plastic material and arranged within the rotor shaft 1. An outer diameter of the cylindrical fixing element 15 is selected such that the fixing element 15 can be pressed into the rotor shaft 1 and is thus connected in a rotationally fixed manner to the inner circumferential surface of the rotor shaft 1. The fixing element 15 accommodates the heat sink 9 in a recess 15i, which comprises a form-fitting section 15e and support sections 15f, g. Furthermore, the fixing element 15 comprises channels in the form of grooves 15a on its outer circumferential surface, which extend axially from an end of the fixing element 15 facing the transmission unit 3 (left end) in the direction of the output-side end (right end). The grooves 15a are arranged distributed in the circumferential direction so that they are in fluid communication with the radial through-bores 1a of the rotor shaft 1.At the output-side end, the fixing element 15 (viewed in a longitudinal direction) comprises, at the level of the first female contact elements 11c of the heat sink 9, a truncated cone-shaped receiving cavity for the first female contact elements 11c, into which the grooves 15a open. The receiving cavity comprises inclined sections 15b that are directed radially inward. The receiving cavity further comprises radial through-openings 15c in the region of the first female contact elements 11c.

[0067] The heat sink 9 is received in the fixing element 15 in a form-fitting manner in the radial direction via the form-fitting section 15e of the fixing element 15. In the assembled state of the rotor arrangement 100, the heat sink 9 (seen in a cross-sectional view perpendicular to the longitudinal direction) has an outer contour that substantially corresponds to an inner contour (seen in a cross-sectional view perpendicular to the longitudinal direction) of the fixing element 15. In Fig. 5, the outer contour of the heat sink 9 and the inner contour of the fixing element 15 are substantially rectangular, at least in the region of the form-fitting section 15e. To insert the heat sink 9 into the fixing element 15, the fixing element 15 comprises, on its inner circumferential surfaces, which point towards the first female contact elements 11c, clearances (or recesses) 15j for the first female contact elements 11c. As shown in Fig.As shown in Figure 5b, the reliefs 15j extend in the axial direction (of the fixing element 15) and are dimensioned and positioned such that the first female contact elements 11c do not collide with the fixing element 15 when the heat sink 9 is inserted (from left to right) into the fixing element 15. An axial limitation of the heat sink 9 in the direction of the output-side end of the fixing element 15 is provided by an axial stop 15d of the fixing element 15. Furthermore, the fixing element 15 comprises a sleeve-shaped stop 15h at its drive-side end, against which the intermediate part 13 abuts.

[0068] The fixing element 15 further comprises support sections 15f, 15g, which support the components of the electronic circuits 11 against centrifugal force. For this purpose, the fixing element 15 is designed such that it encompasses the components in the region of the electronic circuits 11. As shown in Fig. 5a, b, the support sections 15f, 15g may have a stepped configuration if the components of the electronic circuits 11 have different heights.

[0069] In Fig. 5c it is further evident that at least on the sides of the heat sink 9 which do not have any electronic components, the fixing element 15 receives the heat sink 9 (as in the region of the form-fitting section 15e) in a substantially form-fitting manner at the level or in the region of the support sections 15f, 15g.

[0070] In principle, it is also possible to provide the fixing element 15 for the rotor assembly 100 according to the first embodiment. Depending on the requirements, the fixing element 15 in the rotor assembly 100 according to the first embodiment can also only support or fix the heat sink 9, possibly without supporting the components of the electronic circuit 11 and the cooling medium guide.

[0071] With reference to Fig. 6, the cooling medium flow in the rotor assembly 100' is described.

[0072] In Fig. 6, the cooling medium is guided into the fluid channel 9b via the cooling medium supply line 203. The cooling medium flows in the direction of the transmission unit 3. In the region of the intermediate element 13, the cooling medium flow corresponds to that in Fig. 4, so that the statements made for Fig. 4 also apply to Fig. 6. The cooling medium flows via the gap between the collar 13c of the intermediate element 13 and the hollow socket 9a of the heat sink 9 into the grooves 15a and from there in the direction of the output side of the rotor shaft 1 (to the right) and through the radial through-bores 1a. Furthermore, any leakage of the cooling medium that may occur between the cooling medium supply line 203 and the fluid line 9b can be guided via the funnel-shaped opening 9c of the heat sink 9a to the inclined sections 15b in the direction of the radial through-openings 15c and the grooves 15a. At the radial through-openings 15c, the cooling medium can exit from the fixing element 15 outwards towards the rotor winding.In summary, the fixing element 15 enables positioning and positive locking of the heat sink 9 within the rotor shaft 1 as well as electrical insulation of the heat sink 9 with its electronic circuits 11 from the rotor shaft 1. Furthermore, the fixing element 15 enables guidance of the cooling medium on an inner circumferential surface of the rotor shaft 1 as well as guidance of a leakage of the cooling medium radially outward along the heat sink 9 in the direction of the through-bores 1 a and support of the components of the electronic circuits 11 against a centrifugal force.

[0073] Reference symbol rotor shaft a radial through-holes transmission unit primary side a primary ferrite core b primary winding secondary side a secondary ferrite core b secondary winding heat sink a hollow socket b fluid line I electronic circuit 1a rectifier unit 1b male contact element 1 c first female contact element 3 intermediate element 3a annular disc 3b receiving sleeve 3c collar 3d collar opening 3f collecting area (cooling medium chamber) 3g second female contact element 5 fixing element 5a grooves 5b inclined sections 5c radial through-holes 5d axial stop 5e form-fitting section 5f , g supporting sections 5h sleeve-shaped stop i recess j clearance 0 rotor arrangement according to first embodiment 0' rotor arrangement according to second embodiment 1 journal 3 cooling medium supply line

Claims

Patent claims 1. Rotor arrangement (100, 100') for a separately excited synchronous machine, comprising: - a rotor shaft (1) designed as a hollow shaft for an excitation winding; - a transmission unit (3) for contactless transmission of a current required for rotor field generation to the excitation winding, wherein the transmission unit (3) is arranged in the rotor shaft (1); and - a hollow heat sink (9) arranged in the rotor shaft (1) and configured to convey a cooling medium towards an end face of the transmission unit (3), wherein the heat sink (9) comprises a rectifier unit (11a) for the transmitted current on an outer surface.

2. Rotor arrangement (100, 100') according to claim 1, wherein the heat sink (9) has a multi-layer structure, the multi-layer structure comprising a dielectric layer (92), a conductor layer (93) and an insulating layer (94).

3. Rotor arrangement (100, 100') according to claim 1 or 2, wherein the outer surface of the heat sink (9) is planar.

4. Rotor assembly (100, 100') according to one of the preceding claims, further comprising an intermediate element (13) arranged between the transmission unit (3) and the heat sink (9) and comprising: - an annular disc (13a); and - a receiving sleeve (13b) connected at one end to an inner edge of the annular disc (13a).

5. Rotor assembly (100, 100') according to claim 4, wherein a free end of the receiving sleeve (13b) comprises a radially inwardly projecting collar (13c).

6. Rotor arrangement (100, 100') according to claim 5, wherein the receiving sleeve (13b) and the collar (13c) delimit a cooling medium chamber (13f).

7. Rotor arrangement (100, 100') according to one of claims 4 to 6, wherein the heat sink (9) has a hollow socket (9a) which projects into the receiving sleeve (13b).

8. Rotor arrangement (100, 100') according to one of claims 4 to 7, wherein a gap is provided between the collar (13c) and the heat sink (9) for guiding the cooling medium from the receiving sleeve (13b) radially outwards in the direction of an inner wall of the rotor shaft (1).

9. Rotor arrangement (100') according to one of the preceding claims, which further comprises a cylindrical fixing element (15) via which the heat sink (9) is connected to the rotor shaft (1) in a rotationally fixed manner.

10. Rotor arrangement (100') according to claim 9, wherein the fixing element (15) comprises a form-fitting section (15e) for receiving the heat sink (9) and for form-fitting connection in the radial direction.

11. Rotor arrangement (100') according to claim 9 or 10, wherein the fixing element (15) comprises a support portion (15f, 15g) for supporting the rectifier unit (11a) against a centrifugal force.

12. Rotor arrangement (100') according to one of claims 9 to 11, wherein the fixing element (15) comprises an axially extending groove (15a) on an outer peripheral surface.

13. Separately excited synchronous machine with a rotor arrangement (100) according to one of claims 1 to 12 and a stator.

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