Rotor arrangement for a separately excited synchronous machine

Abstract

The present invention relates to a rotor arrangement (100) for a separately excited synchronous machine. The rotor arrangement (100) comprises a rotor shaft (1) designed as a hollow shaft for an excitation winding, a transmission unit (3) for the 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 toward 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. The invention further relates to a separately excited synchronous machine.

Description

The present invention relates to a rotor arrangement for a separately excited synchronous machine.Externally excited synchronous machines can be used in motor vehicles as drive devices and comprise-unlike permanently excited synchronous machines-a rotor-side exciter winding (rotor winding) which can be energized in order to generate an exciter field which interacts with a stator field in order to generate a rotational movement of the rotor.It is known from the prior art that an alternating current provided by the power electronics can be transmitted in contactless fashion by an inductive (current / rotation) transmission device. Such an inductive transmission device may be a (for example 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 in a spatially fixed manner in the electric machine, for example on the housing, and the secondary unit, on the other hand, is rotatable, 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 unit in a contactless manner to the secondary winding of the secondary unit. A rectifier unit connected to the secondary winding extracts the transmitted alternating current and converts it into a direct current for energizing the rotor windings.Previous cooling concepts have insufficient cooling capacity of components of the rectifier unit and of the transmission device.The object of the present invention is to improve cooling of components of the rectifier unit and / or of the inductive transmission device.The object is achieved by a rotor arrangement according to claim 1 and a separately excited synchronous machine according to claim 9.A first aspect of the invention relates to a rotor arrangement for a separately excited synchronous machine, comprising:a rotor shaft, designed as a hollow shaft, for an exciter winding;an inductive transmission unit for the contactless transmission of a current required for rotor field generation to the exciter winding, wherein the transmission unit is arranged in the rotor shaft; anda hollow cooling body which is arranged in the rotor shaft and is configured to convey a cooling medium in the direction of an end side of the transmission unit, wherein the cooling body comprises a rectifier unit for the transmitted current on an outer surface, in particular an outer circumferential surface.The rotor shaft carries the exciter winding. The exciter winding (rotor winding) can be energized in order to generate the rotor-side magnetic field (rotor field). The rotor field then interacts with a stator-side magnetic field (stator field), so that the rotor shaft and thus the rotor arrangement are driven.The inductive transmission unit is provided to transmit the current for the rotor field generation to the rotor winding. For this purpose, the transmission unit comprises a stator-side primary side which comprises a primary ferrite core having a primary-side winding (primary winding) and a rotor-side secondary side which comprises a secondary ferrite core having a secondary-side winding (secondary winding). The primary side is provided 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 each other by an air gap through which the cooling medium for cooling the transmission unit can flow.The transmission unit is arranged at one end of the rotor shaft and is at least partially inserted into the rotor shaft. In some examples, the transmission unit is arranged entirely in the rotor shaft. The end of the rotor shaft having the transmission unit is referred to as a drive-side end. In contrast, an output-side end of the rotor shaft is located.The cooling body is hollow and elongated and guides the cooling medium in a direction from the output-side end of the rotor shaft to the transmission device. The cooling body comprises a cavity, for example a fluid line, for transmitting the cooling medium, which extends over the entire length of the cooling body, for example axially. In a cross-sectional view (in the direction of the longitudinal axis of the cooling body), the fluid line is arranged centrally. In some examples, the fluid conduit may be drilled. In other examples, the heat sink may be molded with a core for the fluid conduit to form the fluid conduit.The cooling body is arranged at least partially in the rotor shaft and lies within the rotor shaft in such a way that the fluid line is arranged coaxially with respect to the axis of rotation of the rotor shaft.The rectifier unit for rectifying and transmitting the current from the secondary winding of the transmission unit to the rotor winding is disposed on the outer surface of the heat sink. In addition, further components (an electronic circuit) may be located on the outer surface of the heat sink next to the rectifier unit. These components comprise, for example. The invention also relates to conductive tracks, contact elements (e.g. plug connections for connecting the secondary winding of the transmission 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. varistor, suppressor diodes (TVS diodes)), further active and / or passive components for implementing safety functions or for transmitting signals.In some examples, the rectifier unit is arranged (optionally distributed) on an outer circumferential surface of the heat sink. The outer circumferential surface is here (as viewed from the longitudinal axis of the cooling body) a surface of the cooling body pointing radially outwards.By providing the rectifier unit directly on an outer surface of the cooling body, improved cooling of the rectifier unit can be achieved.In some embodiments, the heat sink may have a multilayer structure, wherein the multilayer structure comprises a dielectric layer, a conductor track layer and an insulating layer, in particular a solder resist layer. That is, in a cross-sectional view, the heat sinks (from the inside to the outside) include the dielectric layer, the wiring layer, and the insulating layer. The layer structure can be realized, for example, by producing an insulated metal substrate (also: IMS), in which the dielectric layer and the conductor track layer (for example. The heat sink can be applied to a metallic base body (for example made of aluminum) by pressing under the action of temperature.In some examples, the dielectric layer may have a thickness of 50 to 200 μm and / or the conductive trace layer may have a thickness of 20 to 200 μm. The solder resist layer can have a thickness of 10 up to 100 μm, for example.The conductor tracks in the conductor track layer can be formed, for example, from copper.In some examples, the multilayer structure may also be present in multiple instances. This means that the multilayer structure can be present several times one above the other in order to produce a multilayer printed circuit board having a plurality of conductor track layers (i.e. a plurality of planes having copper tracks).In some embodiments, the outer surface of the heat sink may be planar. As a result, the rectifier unit can be applied to the cooling body in a particularly simple manner.In some examples, the heat sink may also have a plurality of planar outer surfaces. For example, the heat sink can be substantially cuboidal in design and therefore have four planar outer circumferential surfaces on which electronic structural elements and / or contact elements can be applied.In some embodiments, the rotor assembly may further include an intermediate member disposed between the transfer unit and the heat sink. The intermediate element comprises:an annular disc; anda receiving sleeve connected at one end to an inner edge of the annular disc.The intermediate element can be formed from an insulating plastic, for example, and can be configured to be substantially rotationally symmetrical. The annular disc includes an inner hole defined by the inner rim of the annular disc. The receiving sleeve can be cylindrical. The receiving sleeve is connected at one end to the inner edge. The receiving sleeve is further connected to the annular disc such that an inner periphery of the receiving sleeve and the inner hole are aligned with each other.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 cooling body.The receiving sleeve of the intermediate element receives the cooling body in the assembled state of the rotor arrangement. This means that the receiving sleeve and the cooling body axially overlap or overlap.The intermediate element may comprise contact elements that transmit a transmission of the current from the transmission unit to the rectifier unit. For this purpose, the secondary winding of the transmission unit is connected to the contact element on the intermediate element side, which is arranged on a side of the intermediate element facing the cooling body. The contact element on the intermediate element side is connected to a correspondingly configured contact element of the rectifier unit, which is arranged on the heat sink.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 which is connected to the annular disc.The collar extends radially inward from the free end with respect to the longitudinal axis of the receiving sleeve. In some examples, the collar extends perpendicular to the longitudinal axis of the receiving sleeve.As mentioned above, the receiving sleeve receives the cooling body. For this purpose, in this embodiment the collar has a collar opening.In some embodiments, the receiving sleeve and the collar can delimit a collecting region for the cooling medium. The cooling medium, which is directed from the cooling body toward the transfer unit, is collected in the collection region. Starting from the collecting region, the cooling medium can flow through the air gap of the transfer unit, which is present between the primary unit and the secondary unit, and thus cool the transfer unit. The collecting region can ensure that a minimum amount of the cooling medium can flow through the air gap of the transmission unit.In some embodiments, the cooling body can have a hollow connecting piece which projects into the receiving sleeve and through the collar opening. Thus, the intermediate element and the hollow connector overlap or overlap in the axial direction. The hollow connector is connected to the fluid line of the cooling body in a fluid-conducting manner. The hollow connector enables a targeted conveying of the cooling medium into the receiving sleeve and in particular into the collecting region. Furthermore, the accommodation of the hollow connector in the collar opening also enables a positioning of the cooling body relative to the intermediate element.In some embodiments, a gap can be provided between the collar and the cooling body, in particular the hollow connector, for guiding the cooling medium from the receiving sleeve radially outwards in the direction of an inner wall of the rotor shaft.The collar and the cooling body or its hollow connection piece are designed in such a way that, in an assembled state of the rotor arrangement, there is a gap between the collar and the outer circumferential surface of the cooling body or of the hollow connection piece. Via the gap, the cooling medium can flow radially outwards from the receiving sleeve or the collecting region in the direction of the inner wall of the hollow shaft. The gap thus enables cooling of the rotor shaft.In some embodiments, the rotor arrangement can furthermore comprise a cylindrical fixing element, by means of which the cooling body can be connected to the rotor shaft in a rotationally fixed manner. For this purpose, the fixing element can be arranged between the cooling body and the rotor shaft in the radial direction of the rotor arrangement and can at least partially accommodate the cooling body axially. For receiving the cooling body, the fixing element comprises an elongate recess. The fixing element makes it possible to electrically isolate the rectifier unit of the cooling body 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 additionally to the press fit, a rotation prevention means for the fixing element can also be provided, for example by 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 cooling body in the rotor shaft.In some embodiments, the fixing element can have a form-fit section for receiving the cooling body and for form-fit connection of the cooling body in the radial direction. The form-fitting section enables a form-fitting 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 of cuboidal design, the recess in the region of the form-fit section (as seen in a cross-sectional view perpendicular to the longitudinal direction) can have a rectangular inner contour which corresponds to the outer contour of the heat sink. In the assembled state, the cooling body is thereby fixedly 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, for example a tongue-and-groove connection between the fixing element and the cooling body.In some embodiments, the fixing element may comprise a support portion 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 surrounds the rectifier unit. In other examples, in which further electronic components are provided on the cooling body in addition to the rectifier unit, these electronic components can likewise be supported against the centrifugal force by further corresponding support sections.In some embodiments, the fixing element can comprise an axially running 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 side of the fixing element facing the transmission unit in the direction of the other end side. The cooling medium can be guided outwards through the groove to a radial through bore in the rotor shaft and from there in the direction of the rotor winding. Furthermore, the cooling medium can be guided along the inner wall of the rotor shaft by means of the groove and thus cool the latter.A second aspect of the invention relates to a separately excited synchronous machine having a rotor arrangement according to one of the embodiments described above. The externally excited synchronous machine can be used as a drive machine for a motor vehicle.Embodiments of the invention will now be described by way of example and with reference to the accompanying drawings. The following shows: FIG. 1 aschematically illustrates a rotor arrangement according to a first embodiment; FIG. 1 bschematically illustrates an enlarged detail in the rotor arrangement according to FIG. 1 a; FIG. 2 shows a perspective view of a cooling body of the rotor arrangement; FIG. 3 is a cross-sectional view of the heat sink; FIG. 4 schematically shows a cooling medium flow through the rotor arrangement from FIG. 1 a; FIG. 5 aschematically illustrates a rotor arrangement according to a second embodiment; FIGS. 5 b, c show perspective representations of the rotor arrangement according to the second embodiment; and FIG. 6 schematically shows a cooling medium flow through the rotor arrangement from FIG. 5 a.FIG. 1 shows a rotor arrangement 100 according to a first embodiment for a separately excited synchronous machine. The rotor arrangement 100 comprises a rotor shaft 1 designed as a hollow shaft, an inductive transmission unit 3 for the contactless transmission of current to a rotor winding (not shown) and a cooling body 9 for carrying a cooling medium.The transmission unit 3 is arranged inside the rotor shaft 1 and comprises a primary side 5 with a primary ferrite core 5 aand a primary winding 5 b. The primary ferrite core 5 ais designed rotationally symmetrically and is plugged onto a journal 201 of a stator (not shown) and is thus firmly connected to the stator. In the present case, the primary ferrite core 5 aincludes an axial (sleeve-shaped) section and a radially outwardly projecting section. The primary winding 5b wraps at least partially around the primary ferrite core 5a at its axial portion.Furthermore, the transmission unit 3 comprises a secondary side 7 with a secondary ferrite core 7 aand a secondary winding 7 b. The secondary ferrite core 7a comprises an axial (sleeve-shaped) portion and a radially inwardly projecting portion. The secondary winding 7b is inserted in the secondary ferrite core 7a. The secondary ferrite core 7 ais connected to the rotor shaft 1 in a rotationally fixed manner and is thus rotatable relative to the primary ferrite core 5 a. For example, the secondary ferrite core 7 amay be rotationally fixedly coupled at its outer circumferential surface along the axial portion to an inner circumferential surface of the rotor shaft 1.The primary winding 5 band the secondary winding 7 bare framed by the axial and radial portions of the primary ferrite core 5 aand the secondary ferrite core 7 aand axially overlap at least partially (as seen in the longitudinal direction of the rotor arrangement 100 and rotor shaft 1, respectively). In other embodiments (not shown), the primary windings 5a and the secondary windings 7b may also overlap completely axially.The cooling body 9 is of elongate design and is arranged in the rotor shaft 1 and coaxially with respect to its longitudinal axis. In this case, the cooling body 9 is connected to the rotor shaft 1 in a rotationally fixed manner (for example via a fixing element 15 described later). At an end of the cooling body 9 facing the transmission unit 3, a hollow connecting piece 9 ais provided. Furthermore, the cooling body 9 comprises a fluid line 9 bextending over the entire length of the cooling body 9. The fluid line 9 bis arranged centrally in the cooling body 9 (in a cross-sectional view of the cooling body 9) and is formed in such a way that, in the assembled state of the rotor arrangement 100, it runs coaxially with respect to the longitudinal axis of the rotor shaft 1. This allows the cooling medium to be guided close to the axis of rotation. Furthermore, the cooling body 9 comprises, at an end facing away from the transmission unit 3, a (cooling body-side) radially inwardly projecting collar 9 c, through which a stator-fixed cooling medium feed line 203 projects. The cooling medium is supplied to the cooling body on the stator side by means of the cooling medium supply line 203. In this case, there is axial overlapping or overlapping between the cooling body 9 and the cooling medium feed line 203. The cooling body 9 can be plugged onto the cooling medium feed line 9 and positioned by the collar 9 con the cooling body side. Furthermore, a seal (not shown) can be provided in the region of the collar 9 c, on the cooling body side, between the cooling body 9 and the cooling medium feed line 203.FIG. 2 shows a perspective illustration of the heat sink 9. the heat sink 9 is of substantially cuboidal configuration and comprises an electronic circuit 11 on a first (upper) outer circumferential surface. The electronic circuit 11 comprises a rectifier unit 11 awhich is connected via a male contact element 11 bto the output of the secondary winding 7 bof the transmission unit 1 and via a first female contact element 11 cto an input of the rotor winding (not shown). The male contact element 11 band the first female contact element 11 care each present in pairs in order to contact both electrical poles of the secondary winding 7 band of the rotor winding, respectively. The male contact element 11 bis L-shaped in FIG. 1 a. In other examples, a different shape may also be possible. As is also seen from FIG. 1 a, a second electronic circuit 11 is present on a second outer circumferential surface which is opposite the first outer circumferential surface. In other examples, the electronic circuits 11 may also be arranged distributed on other outer surfaces. Furthermore, the electronic circuits 11 can comprise at least one of the following structural and / or contact elements, such as, for example. Components for limiting induced voltage peaks (varistor, 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 cooling body 9, a particularly effective cooling of the electronic circuits 11 can take place.FIG. 3 schematically shows a cross-sectional view of the heat sink 9 along the line A-A shown in FIG. 1. The heat sink comprises a base body 91 which is made of a thermally conductive material, for example. Metal is formed. In one example, the base body 91 is formed 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, for example, 50 μm to 200 μm, and a conductor track layer 93, which can have a thickness of, for example, copper and / or a thickness of 20 μm to 200 μm. Finally, a solder resist layer 94 can also be provided, which has a thickness of 10 μm up to 100 μm. In some examples, the layer structure can be provided only in a partial area of the side, i.e. in the region of the electronic circuits 11. In other examples, the layer structure may extend over the entire side. In further examples, the layer structure comprising the dielectric layer 92 and the conductor track layer 93 can also be present at least partially multiple times one above the other in order to produce a multilayer printed circuit board. If printed circuit board arrangements, such as the electrical circuits 11, are provided on a plurality of outer surfaces of the cooling body 9, these can be electrically conductively connected to one another with the aid of additional conductor track layers 93.In principle, the layer structure and thus the arrangement of the electronic circuits 11 can also be present only on one or more sides of the cooling body 9. It is also possible for the electronic circuits 11 to be distributed on all sides of the heat sink 9, with the result that the layer structure is also present accordingly on all sides.A production sequence for the heat sink 9 can be carried out in accordance with known methods 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 action of temperature.In order to provide a required electrical insulation (air and creepage distances) between the electronic structural and contact elements of the electronic circuits 11, a further solder resist layer 94 aor another coating with another electrical insulator can also optionally be present on the cooling body 9 on further intermediate regions between the elements of the electronic circuit 11. In some examples, the further solder resist layer 94 amay also be formed integrally with the solder resist layer 94.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 for the further solder resist layer 94 ato be provided on the surfaces on which no circuits or conductor tracks are placed, in order to isolate the conductive heat sink 9 from the current-carrying elements of the electronic circuits 11.Referring again to FIG. 1 a, the rotor arrangement 100 further comprises an intermediate element 13 arranged axially between the transmission unit 3 and the cooling body 9. The intermediate element 13 enables the cooling medium to be guided in the region of the rotor shaft 1, in particular in a region on the side of the transmission unit 3, as will be described later with reference to FIG. 4. During the assembly of the rotor arrangement 100, the cooling body 9 with the electronic circuit 11 is inserted axially from the drive side (from the left) into the rotor shaft 1 and subsequently the transmission unit 3 with the intermediate element 13.The intermediate element 13 is formed from a plastic material, for example an electrically insulating plastic material. The intermediate member 13 includes an annular disc 13a as a base and a receiving sleeve 13b extending from the annular disc 13a and arranged coaxially with the annular disc 13a. At this time, an inner hole 13e of the annular disc 13a is aligned with the inner periphery of the receiving sleeve 13b. Thus, an edge of the inner hole 13 eand an end of the receiving sleeve 13 bare connected to each other. At another (free) end, the receiving sleeve 13 bincludes a radially inwardly projecting collar 13 c. The collar 13c forms a collar opening 13d for receiving the hollow stub 9a of the cooling body 9.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. As a result, the current transmitted from the transmission unit 3 can be passed on to the rotor winding via the female contact element 13 g, the male contact element 11 b, the rectifier unit 11 and the first female contact element 11 c.The intermediate member 13 has an outer diameter at its base (annular disc 13a) substantially corresponding to the inner diameter of the rotor shaft 1. The intermediate member 13 abuts with one side of the annular disc 13 axially with the transmission unit 3. Furthermore, the receiving sleeve 13 b, the collar 13 cand an end side of the transmission unit 13 facing the intermediate element 13 delimit a collecting region 13 ffor the cooling medium provided via the cooling body 9. The collar 13 dis used to ensure that a minimum amount of cooling medium flows through an air gap in the transmission unit 3. The collar 13 cor the collar opening 13 dis dimensioned such that a gap is present between the hollow connecting piece 9 aand the inner edge of the collar opening 13 d, via which gap the cooling medium can flow out of the collecting region 13 fin the direction of an inner wall of the rotor shaft 1.The rotor shaft 1 includes radial through holes 1 afor guiding the cooling medium from an inside of the rotor shaft 1 to the outside toward the rotor windings. In FIGS. 1 aand 1 b, two radial through-bores 1 aare illustrated, which are arranged diametrically with respect to one another. Alternatively, the radial through-bores 1 acan also be distributed differently in the circumferential direction. In other examples, only a single radial through bore 1 acan be provided. In further examples, a plurality of radial through-holes 1 amay be arranged (uniformly) distributed in the circumferential direction of the rotor shaft. Distribution of the radial through-bores 1a in the axial direction is also possible.FIG. 4 schematically shows a cooling medium flow indicated by arrows in the rotor arrangement 100 from FIG. 1 a. 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 feed line 203 to the cooling body 9, in particular to the fluid line 9 b(rotating with the rotor shaft 1 during operation). At a second transfer point, which is located on the side of the transfer unit 3, the cooling medium opens into the collecting region 13 f. From there, the cooling medium flows via the air gap between the primary ferrite core 5 aand the secondary ferrite core 7 ato the primary winding 5 band the secondary winding 7 band then to a side opposite to the output side of the rotor arrangement 100 (to the left in FIG. 3 ). Further, due to the rotation generated during operation of the externally excited synchronous machine, the cooling medium flows toward the inner wall of the rotor shaft 1 via the gap between the collar 13 cand the cooling body 9.FIGS. 5a-c schematically show a rotor arrangement 100' according to a second embodiment in sectional representations. In this case, FIGS. 5b and 5c show perspective sectional representations, wherein the representation of the rotor arrangement 100' from FIG. 5b is rotated about 90° about the longitudinal axis compared to the representation from FIG. 5c. The rotor arrangement 100' according to the second embodiment differs from the rotor arrangement 100 according to the first embodiment in that the cooling body 9, which according to the second embodiment has a funnel-shaped opening 9 cin its output-side end instead of a collar. In the rotor arrangement 100' according to the second embodiment, the radial through-holes 1a are also present, but are hidden in FIGS. 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 of cylindrical design and is of substantially symmetrical construction with respect to a plane which lies perpendicular to the plane of the drawing of FIG. 6 (described later) and comprises the longitudinal axis of the fixing element 15.The fixing element 15 is formed from a plastic material and is arranged inside 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 to the inner circumferential surface of the rotor shaft 1 in a rotationally fixed manner. The fixing element 15 accommodates the cooling body 9 in a recess 15 ithat comprises a form-fit section 15 eand support sections 15 f, g. The fixing element 15 further comprises channels on its outer circumferential surface in the form of grooves 15 awhich extend axially from an end (left end) of the fixing element 15 facing the transmission unit 3 in the direction of the output-side end (right end). The grooves 15 aare arranged distributed in the circumferential direction, so that they are in fluid communication with the radial through-bores 1 aof the rotor shaft 1. At the output-side end, the fixing element 15 comprises, at the level of the first female contact elements 11 cof the heat sink 9, a frustoconical receiving cavity for the first female contact elements 11 c, into which the grooves 15 aend. The receiving cavity comprises inclined portions 15b directed radially inwardly. The receiving cavity further comprises radial through-openings 15 cin the region of the first female contact elements 11 c.The heat sink 9 is received in the fixing element 15 in a positive-locking manner in the radial direction via the positive-locking section 15 eof the fixing element 15. In the assembled state of the rotor arrangement 100, the heat sink 9 (as seen in a cross-sectional view perpendicular to the longitudinal direction) has an outer contour which substantially corresponds to an inner contour (as seen in a cross-sectional view perpendicular to the longitudinal direction) of the fixing element 15. In FIG. 5, the outer contour of the cooling body 9 and the inner contour of the fixing element 15 are substantially rectangular at least in the region of the positive-locking section 15 e. For inserting the heat sink 9 into the fixing element 15, the fixing element 15 comprises, on its inner circumferential surfaces which point toward the first female contact elements 11 c, clearances (or recesses) 15 jfor the first female contact elements 11 c. As shown in FIG. 5 b, the clearances 15 jextend in the axial direction (of the fixing element 15) and are dimensioned and positioned in such a way that the first female contact elements 11 cdo not collide with the fixing element 15 when the heat sink 9 is introduced (from left to right) into the fixing element 15. An axial delimitation of the cooling body 9 in the direction of the output-side end of the fixing element 15 is provided by an axial stop 15 dof the fixing element 15. The fixing element 15 further comprises a sleeve-shaped stop 15 hon its drive-side end, against which the intermediate part 13 abuts.The fixing element 15 further has the support portions 15 f, 15 gwhich support the components of the electronic circuits 11 against centrifugal force. For this purpose, the fixing element 15 is designed in such a way that it surrounds the components in the region of the electronic circuits 11. As shown in FIGS. 5 a, b, a step-shaped configuration of the support sections 15 f, 15 gmay occur when the components of the electronic circuits 11 have different heights.It can also be seen in FIG. 5 c that, at least on sides of the heat sink 9 which do not have electronic components, the fixing element 15 at the height of or in the region of the support sections 15 f, 15 g substantially positively accommodates the heat sink 9 (as in the region of the positive-locking section 15 e).In principle, it is also possible to provide the fixing element 15 for the rotor arrangement 100 according to the first embodiment. Depending on the need, the fixing element 15 in the rotor arrangement 100 according to the first embodiment can also only take over the support or fixing of the cooling body 9, if appropriate without supporting the components of the electronic circuit 11 and the guidance of the cooling medium.Referring to Fig. 6, the flow of cooling medium in the rotor assembly 100' will be described.In FIG. 6, the cooling medium is conducted into the fluid channel 9 bvia the cooling medium feed line 203. The cooling medium flows in the direction of the transfer unit 3. In the region of the intermediate element 13, the cooling medium flow corresponds to that of FIG. 4, so that the explanations made for FIG. 4 also apply to FIG. 6. The cooling medium flows via the gap between the collar 13 cof the intermediate element 13 and the hollow connection piece 9 aof the cooling body 9 into the grooves 15 aand from there in the direction of the output side of the rotor shaft 1 (to the right) and through the radial through-bores 1 a. Furthermore, a leakage of the cooling medium, which may occur between the cooling medium feed line 203 and the fluid line 9 b, can be guided via the funnel-shaped opening 9 cof the cooling body 9 ato the oblique sections 15 bin the direction of the radial through-openings 15 cand the grooves 15 a. At the radial through-openings 15 c, the cooling medium can pass out of the fixing element 15 outwards in the direction of the rotor winding.In summary, the fixing element 15 enables positioning and form-fitting of the cooling body 9 within the rotor shaft 1 and electrical insulation of the cooling body 9 with its electronic circuits 11 with respect to the rotor shaft 1. furthermore, the fixing element 15 enables guiding of the cooling medium on an inner circumferential surface of the rotor shaft 1 and guiding of a leakage of the cooling medium radially on the outside along the cooling body 9 in the direction of the through-bores 1 aand supporting of the components of the electronic circuits 11 against a centrifugal force.Reference numerals denote reference numerals1 Rotor shaft 1a Radial through-bores 3 Transmission unit 5 Primary side 5a Primary ferrite core 5b Primary winding 7 Secondary side 7a Secondary ferrite core 7b Secondary winding 9 Cooling body 9a Hollow connection piece 9b Fluid line 11 Electronic circuit 11a Rectifier unit 11b Male contact element 11c First female contact element 13 Intermediate element 13a Annular disc 13b Receiving sleeve 13c Collar 13d Collar opening 13f Collecting region (cooling medium chamber) 13g Second female contact element 15 Fixing element 15a Grooves 15b Oblique sections 15c Radial through-openings 15d Axial stop 15e Positive locking section 15f, g Support sections 15h Sleeve-shaped stop 15i Recess 15j Clearance 100 Rotor arrangement according to first embodiment 100' Rotor arrangement according to second embodiment 201 Journal 203 Cooling medium feed line

Claims

Rotor arrangement (100, 100') for a separately excited synchronous machine, comprising: - a rotor shaft (1) designed as a hollow shaft for an exciter winding; - a transmission unit (3) for the contactless transmission of a current required for rotor field generation to the exciter winding, wherein the transmission unit (3) is arranged in the rotor shaft (1); and - a hollow cooling body (9) arranged in the rotor shaft (1) and configured to convey a cooling medium in the direction of an end face of the transmission unit (3), wherein the cooling body (9) comprises a rectifier unit (11a) for the transmitted current on an outer surface.The rotor assembly (100, 100') of claim 1, wherein the heat sink (9) has a multilayer structure, the multilayer structure comprising a dielectric layer (92), a conductive trace layer (93), and an insulating layer (94).Rotor arrangement (100, 100') according to Claim 1 or 2, wherein the outer surface of the cooling body (9) is planar.The rotor assembly (100, 100') according to any one of the preceding claims, further comprising an intermediate element (13) arranged between the transfer 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).The rotor assembly (100, 100') of claim 4, wherein a free end of the receiving sleeve (13b) comprises a radially inwardly projecting collar (13c).The rotor assembly (100, 100') of claim 5, wherein the receiving sleeve (13b) and the collar (13c) define a cooling medium chamber (13f).Rotor arrangement (100, 100') according to one of Claims 4 to 6, wherein the cooling body (9) has a hollow connection piece (9a) which projects into the receiving sleeve (13b).Rotor arrangement (100, 100') according to one of Claims 4 to 7, wherein a gap is provided between the collar (13c) and the cooling body (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).Rotor arrangement (100') according to one of the preceding claims, which further comprises a cylindrical fixing element (15), via which the cooling body (9) is connected to the rotor shaft (1) in a rotationally fixed manner.Rotor arrangement (100') according to claim 9, wherein the fixing element (15) comprises a form-fit section (15e) for receiving the cooling body (9) and for form-fit connection in the radial direction.The rotor assembly (100') according to claim 9 or 10, wherein the fixing member (15) comprises a support portion (15f, 15g) for supporting the rectifier unit (11a) against a centrifugal force.Rotor arrangement (100') according to one of Claims 9 to 11, wherein the fixing element (15) comprises an axially running groove (15a) on an outer circumferential surface.Externally excited synchronous machine having a rotor arrangement (100) according to one of Claims 1 to 12 and a stator.

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