Rotor component and method for producing a rotor of an electric machine

Abstract

The invention relates to a method for producing a current-excited rotor. The method comprises providing a rotor body having electrically conductive windings, and potting the rotor body with a potting compound such that an electrically conductive winding interface to the windings remains accessible. The method further comprises, subsequently to the potting, connecting the winding interface to an electrical energy supply in order to provide an excitation current for the windings.

Description

[0001] Rotor component and method for manufacturing a rotor of an electric machine

[0002] The invention relates to an electric machine, such as a synchronous machine. In particular, the invention relates to a method for manufacturing a rotor for an electric machine.

[0003] A vehicle that is at least partially electrically powered comprises an electric machine for propelling the vehicle. The electric machine includes a stator that encloses a rotor of the electric machine, wherein a current-excited rotor has a rotor body with rotor slots in which electrically conductive windings are arranged to generate a magnetic field. The windings of the rotor form a winding head at each end face of the rotor.

[0004] During operation of the electric machine, the rotor is subjected to relatively high stress due to centrifugal force. This applies particularly to the windings in the rotor slots and / or on the end faces of the rotor body. The rotor slots can each be covered by a slot closure wedge, which retains the windings in the respective rotor slots. Furthermore, the windings can be fixed within the rotor slots and on the end faces of the rotor body using potting compound. The application of heated potting compound is typically associated with a relatively high thermal load on the electrical power supply required to provide the excitation current for the rotor windings, which can impair the electrical power supply.

[0005] This document addresses the technical challenge of enabling a particularly gentle manufacturing process for a rotor using potting compound.

[0006] The problem is solved in each case by the independent claims. Advantageous embodiments are described, inter alia, in the dependent claims. It should be noted that additional features of a claim dependent on an independent claim, without the features of the independent claim or only in combination with a subset of the features of the independent claim, can constitute a separate invention independent of the combination of all features of the independent claim, which can be made the subject of an independent claim, a divisional application, or a subsequent application.

[0007] This applies equally to technical teachings described in the description that can constitute an invention independent of the features of the independent patent claims.

[0008] According to one aspect, a method for manufacturing a current-excited rotor for an electric machine, in particular for a synchronous machine, is described. The method comprises providing a rotor body with electrically conductive windings. The rotor body can have N salient poles (e.g., N = 4 or more, or N = 6 or more). A rotor slot can be arranged between each salient pole. The windings can be arranged around the salient poles in the rotor slots.

[0009] The process further includes potting the rotor body with a potting compound, such that an electrically conductive winding interface to the windings remains accessible (and thus not covered with potting compound). The potting compound can be introduced into the rotor body in a heated and / or liquid state. Subsequently, the potting compound can be cured to provide a rotor component with (cured) potting compound.

[0010] Before potting the rotor body, a (cup-shaped) support body can be positioned on each of its end faces. These support bodies cover the winding head (of the windings) located on the respective end face. During the potting process, the potting compound can be introduced through one or more recesses in one or both support bodies into the rotor slots and / or into the cavity between the support bodies and the respective end face of the rotor body.

[0011] Preferably, slot closure wedges can be positioned on the individual rotor slots of the rotor body before potting to cover the rotor slots. This allows the rotor component to be manufactured with (cured) potting compound in a particularly reliable manner.

[0012] This allows for the provision of a rotor component with (cured) potting compound, featuring an easily accessible winding interface for connecting the windings to an electrical power supply. The winding interface can protrude axially beyond the support body on one of the two end faces of the rotor body (outwards, i.e., away from the rotor body) and thus remain freely accessible (even after potting with the compound).

[0013] The rotor component is preferably designed such that only electrical conductors (e.g., copper conductors) and / or no electronic components and / or slip rings are arranged between the windings and the winding interface. This ensures that the heated potting compound does not cause any thermal damage to the rotor component.

[0014] The process further comprises, following the potting, connecting the winding interface to an electrical power supply to provide the excitation current for the windings. The electrical power supply may include one or more slip rings and / or brushes. Alternatively or additionally, the electrical power supply may include an electronic circuit for the wireless, in particular inductive, transmission of electrical energy to the rotor windings.

[0015] This describes a process in which the rotor body is potted before the windings are electrically connected to an electrical power supply. This avoids thermal stress on the electrical power supply, enabling a particularly reliable and gentle rotor manufacturing process.

[0016] The process can include, following the casting, positioning the rotor shaft in a central recess of the rotor body. In other words, following the casting of the rotor body, the rotor shaft can be guided along with the rotor body. For this purpose, the rotor shaft can be inserted into the central recess of the rotor body.

[0017] Connecting the winding interface to the electrical power supply can be done after the rotor shaft is assembled. This allows for particularly gentle rotor manufacturing. Furthermore, it enables a particularly flexible joining of the rotor shaft. Alternatively, the winding interface can be connected during rotor shaft assembly to enable particularly efficient rotor manufacturing.

[0018] The winding interface can be located on a first end face of the rotor body. The rotor shaft can be positioned in the central recess of the rotor body from the opposite second end face to ensure particularly gentle joining of the rotor shaft.

[0019] According to another aspect, a rotor component for a current-excited rotor of an electric machine is described. The rotor component comprises a rotor body with electrically conductive windings. The rotor component may also have slot closure wedges that cover the individual rotor slots. Furthermore, the rotor component may have support bodies on the end faces of the rotor body that cover the winding heads.

[0020] The rotor body of the rotor component is encased in a (cured) potting compound such that an electrically conductive winding interface to the windings remains accessible. The winding interface can include an electrically conductive contact element, in particular a fork, projecting axially beyond an end face of the rotor body. Alternatively or additionally, the winding interface can be electrically connected to the windings. The winding interface is preferably arranged directly on the rotor body. Furthermore, the winding interface is preferably arranged such that it does not touch the rotor shaft.

[0021] The winding interface can be located on the electrical power transmission path for supplying the excitation current at a point between the rotor shaft and the windings. The electrical power transmission path can further include slip rings and / or a wireless power transmission circuit. The winding interface is preferably located between the windings on the one hand and the slip rings and / or the wireless power transmission circuit on the other.

[0022] The rotor component is designed such that the electrical power supply for providing the excitation current for the windings can be connected to the winding interface after the rotor body has been potted with potting compound. The rotor component can also be designed such that the rotor shaft can be arranged in the central recess of the rotor body after the rotor body has been potted with potting compound.

[0023] This document describes a rotor component that enables a particularly gentle electrical connection of the windings to an electrical power supply. Furthermore, it describes a rotor for an electric machine, which comprises the rotor component described in this document.

[0024] According to another aspect, an electrical machine, in particular a (current-excited) synchronous machine, is described, which includes the rotor described in this document. Furthermore, the electrical machine typically includes a stator.

[0025] According to another aspect, a (road) motor vehicle (in particular a passenger car or a truck or a bus or a motorcycle) is described that includes the electric machine described in this document for propelling the vehicle.

[0026] It should be noted that the methods, devices, and systems described in this document can be used both alone and in combination with other methods, devices, and systems described in this document. Furthermore, any aspect of the methods, devices, and systems described in this document can be combined with one another in a variety of ways. In particular, the features of the claims can be combined with one another in a variety of ways. Features listed in parentheses are to be understood as optional features.

[0027] The invention will now be described in more detail using exemplary embodiments.

[0028] Figure 1a shows an exemplary electrical machine;

[0029] Figure 1b shows a perspective view of an exemplary rotor body;

[0030] Figure 1c shows a perspective view of an exemplary slotted locking wedge;

[0031] Figure 2a shows a perspective view of an exemplary rotor with rotor windings;

[0032] Figure 2b shows a perspective view of an exemplary supporting body;

[0033] Figure 2c shows a perspective view of an exemplary rotor with support bodies; Figure 2d shows a perspective view of an exemplary rotor shaft with a slip ring module;

[0034] Figure 3a shows the end face of an exemplary rotor component;

[0035] Figure 3b shows an exemplary rotor shaft with contact elements; and

[0036] Figure 4 shows a flowchart of an exemplary process for manufacturing a rotor.

[0037] As stated at the outset, this document deals with the efficient and environmentally friendly production of a current-excited rotor for an electric machine. In this context, Fig. 1a shows an exemplary electric machine 100 in a view perpendicular to the shaft 101 of the electric machine 100. The shaft 101 of the electric machine 100 can correspond to the longitudinal axis of the stator 110 and / or the axis of rotation of the rotor 120 of the electric machine 100. Furthermore, the shaft 101 can run along the z-axis of the Cartesian coordinate system shown.

[0038] The electric machine 100 comprises a stator 110 with several stator windings 111 arranged at different angular positions around the rotational axis of the rotor 120, and configured to generate a rotating electromagnetic field. The stator 110 is enclosed by a housing 135 of the electric machine 100.

[0039] Furthermore, the electric machine 100 comprises the rotor 120, which is driven by the rotating magnetic field generated by the stator 110. The rotor 120 is rigidly connected to the shaft 101 driven by the electric machine 100 (which may be connected to the rotor shaft of the rotor 120 or may be identical to the rotor shaft of the rotor 120). The rotor 120 comprises a rotor body 122.

[0040] The rotor 120 of an electric machine 100 can have a laminated iron core (e.g., composed of mutually insulating sheets) as its rotor body 122. Fig. 1b shows an exemplary rotor body 122 of a rotor 120 in a perspective view. The rotor body 122 extends along the axis of rotation or the longitudinal axis of the rotor 120 (i.e., in the axial direction) from a first end face 128 to an opposite second end face 129. In the illustrated example, the rotor body 122 has different salient poles 124 arranged at different angular positions around the axis of rotation of the rotor 120. The salient poles 124 can be evenly distributed around the axis of rotation. A winding can be arranged around each salient pole 124, through which a magnetic field is generated. The individual salient poles 124 can thus form magnetic poles of the rotor 120.

[0041] The rotor body 122 has a central opening or recess 123, in particular a bore, into which the rotor shaft of the rotor 120 can be inserted. The rotor shaft can be rotatably mounted on the end faces of the rotor body 122 via respective bearing surfaces to enable rotation of the rotor 120.

[0042] Between two directly adjacent salient poles 124 of the rotor body 122, a rotor slot 125 is formed in which the windings of the adjacent salient poles 124 are arranged. A rotor slot 125 extends along the longitudinal and / or rotational axis from the first end face 128 to the opposite second end face 129 of the rotor body 122.

[0043] The rotor groove 125 between two directly adjacent (circumferentially) salient poles 124 has an opening 126 on the outer surface of the rotor body 122 facing away from the rotor shaft, the opening 126 extending along the longitudinal axis from the first end face 128 to the second end face 129 of the rotor body 122. In the transverse direction to the longitudinal axis, the opening 126 is bounded by (mutually facing) legs 131 of the pole shoes 130 of the two directly adjacent salient poles 124.

[0044] To manufacture a rotor 120, electrically conductive windings can be wound around the salient poles 124, such that windings of the two directly adjacent salient poles 124 are arranged in each rotor slot 125. After arranging the windings, the openings 126 of the individual rotor slots 125 can each be covered with a slot closure wedge 180 (see Fig. 1c). A slot closure wedge 180 can be inserted from an end face 128 between the legs 131 of the pole shoes 130 of the two directly adjacent salient poles 124 to cover the opening 126.

[0045] Fig. 2a shows a perspective view of a rotor 120 with a rotor body 122, wherein a rotor shaft 202 is arranged in the central opening 123 of the rotor body 122. Furthermore, rotor windings 201 are arranged around each of the individual salient poles 124. The rotor windings 201 form a winding head 206 on each of the two end faces 128, 129 of the rotor body 122. The openings 126 of the individual rotor slots 125, which are to be covered, can be seen between the pole shoes 130 of the individual salient poles 124.

[0046] During operation of the electric machine 100, centrifugal forces in a radial direction act on the rotor 120, in particular on the winding heads 206 on the two end faces 128, 129 of the rotor body 122. These forces could lead to damage to the electric machine 100, especially to the windings 201. To absorb the forces acting on the winding heads 206, a cup-shaped support body, in particular a support ring, 210 can be arranged on each end face of the rotor 120 (see Fig. 2b). The support body 210 has a cover area 212 extending substantially parallel to the respective end face, which covers the respective end face in the axial direction. The cover area 212 has a central, circular recess 216 through which the shaft 202 of the rotor 120 is guided.

[0047] The support body 210 further comprises an annular edge region 213, which extends axially from the outer edge of the cover region 212 towards the rotor body 122. The edge region 213 has an inner surface 214 which, in the installed state of the support body 210, can, for example, rest on support areas 205 (to fix the support body 210 to the rotor body 122). The individual support areas 205 can be formed by the individual pole shoes 130 of the rotor body 122. Preferably, the support body 210 rests on the lateral surface of a star disk, which abuts the end face 128, 129 of the rotor body 122. In this case, the individual support areas 205 are formed by the star disk, in particular by the lateral surface of the star disk.

[0048] Fig. 2c shows an exemplary rotor 120, which has slot locking wedges 180 for covering the windings 201 arranged in the individual rotor slots 125 and a support body 210 on each end face for covering the winding heads 206. The cavities of the rotor 120, in particular in the individual rotor slots 125 and on the end faces 128, 129 of the rotor body 122, are filled with a hardened potting compound to fix the windings 201.

[0049] Fig. 2d shows an exemplary rotor shaft 202 in a perspective view. The rotor shaft 202 has a slip ring module 260 with several, in particular two, slip rings 261. The rotor shaft 202 has a rotor body area 253 (with a circular cylindrical surface) around which the rotor body 122 of the rotor 120 is arranged. Furthermore, the rotor shaft 202 has at least one bearing 252 for supporting the rotor shaft 202 and the rotor 120. The rotor shaft 202 can also have one or more sealing rings 251 for sealing the rotor 120 (to prevent coolant from escaping from the rotor 120).

[0050] The slip ring module 260 is arranged at one end of the rotor shaft 202. Electrical leads 254 can be routed from the individual slip rings 261 under the bearing 252 to the rotor body 122 to electrically connect the windings 201 of the rotor 120. The slip ring module 260 can have a first slip ring 261 for a first electrical pole (e.g., for a positive pole) and a second slip ring 261 for a second electrical pole (e.g., for a negative pole). The electrical leads 254 can be electrically connected to a switching ring 270, the switching ring 270 having a contact element 271, in particular a contact fork, for each lead 254. The potting compound can be introduced into the recess 123 of the rotor body 122 after the rotor shaft 202 has been positioned. The heated (liquid) potting compound can be introduced through the recesses 215 of the support bodies 210.

[0051] The application of the heated potting compound can lead to a relatively high thermal load on the electrical winding interface 170 (e.g., the switching ring) between the windings 201 of the rotor 120 and the power source for supplying the excitation current. In the example shown in Fig. 2d, the electrical winding interface 270 comprises the switching ring with the contact elements 271. The electrical power supply can be provided by the slip ring module 260 and by the conductors 254. In an alternative example, the electrical power supply can be provided by inductive transmission of the excitation current to the windings 201 of the rotor 120. In this case, the electrical power supply can include electronic components to convert the inductively transmitted alternating current into a rectified excitation current.

[0052] The rotor 120 can be designed such that the potting compound can be introduced into the rotor body 122 before the rotor shaft 202 is joined and / or before the (inductive or electrically conductive) connection for supplying the excitation current is established. For this purpose, the rotor 120 can be designed such that an (electrically conductive) winding interface 270, e.g., the switching ring, to the windings 201 of the rotor 120 remains freely accessible even after the potting process has been carried out.

[0053] Fig. 3a shows an end face of a rotor component 300, which includes, for example, the rotor body 122, the windings 201, the slot locking wedges 180, and optionally the end-face support bodies 210. The rotor component 300, however, does not have a rotor shaft 202. Furthermore, the rotor component 300 has an accessible winding interface 270 (e.g., on an end face) through which the excitation current for the windings 201 can be supplied. Potting compound can be introduced into the rotor component 300, for example, via the recesses 215 of the support bodies 210, to fix the windings 201 and the winding heads 206. A potted rotor component 300 can thus be provided, whereby the winding interface 270 remains accessible even after potting the rotor component 300 (and is not covered with potting compound).

[0054] In a subsequent step, the rotor shaft 202 can be inserted into the recess 123 of the rotor body 122, and the electrical connection to the winding interface 270 can be made (e.g., via the lines 254), so that the excitation current can be supplied to the windings 201. Because the potting of the rotor component 300 has already been carried out beforehand, there is no thermal stress on the electrical connection (e.g., for the components of an inductive transmission unit for the excitation current).

[0055] The rotor component 300 (i.e., the wound laminated core) can thus be potted before electrical connection. The design of the rotor component 300 ensures that the winding interface 270 (e.g., a fork, a flag, or a cup) remains exposed for electrical contacting of the windings 201 even after potting. Electrical contacting can be carried out during or after joining the rotor shaft 202.

[0056] The rotor shaft 202 and the rotor body 122 can be connected to each other, for example, via a longitudinal press fit (e.g., using a forming bore) to transmit torque. Alternatively or additionally, the rotor shaft 202 can be thermally shrunk for the joining process. The transmission unit for providing the excitation current can then be installed after the joining process. This ensures that the transmission unit is not affected by thermal influences (during the cooling of the rotor shaft 202 and / or during the application of the potting compound).

[0057] Fig. 4 shows a flowchart of an exemplary method 400 for manufacturing a current-excited rotor 120. The method 400 comprises providing 401 a rotor body 122 with electrically conductive windings 201. The windings 201 are arranged in the rotor slots 125 of the rotor body 122. The method 400 further comprises potting 402 the rotor body 122 with a potting compound such that an electrically conductive winding interface 170 to the windings 201 remains accessible (and is not covered with potting compound). The potting 402 can be carried out before the rotor shaft 202 is joined to the rotor body 122. The winding interface 170 can be located directly on the rotor body 122 (in particular on an end face 128, 129 of the rotor body 122).

[0058] Furthermore, the method 400, following the potting 402, includes connecting 403 the winding interface 170 to an electrical power supply to provide an excitation current for the windings 201. The electrical power supply can, for example, include one or more slip rings 261. Alternatively or additionally, the electrical power supply can include a circuit for wireless electrical power transmission.

[0059] The measures described in this document can result in a particularly gentle and reliable manufacturing process for a rotor 120 of an electric machine 100.

[0060] The present invention is not limited to the embodiments shown. In particular, it should be noted that the description and the figures are intended only to illustrate the principle of the proposed methods, devices, and systems by way of example.

Claims

Claims 1) Method (400) for manufacturing an electrically excited rotor (120); wherein the method (400) comprises, - Providing (401) a rotor body (122) with electrically conductive windings (201); - Potting (402) the rotor body (122) with a potting compound in such a way that an electrically conductive winding interface (170) to the windings (201) remains accessible; and - following the potting (402), connecting (403) the winding interface (170) to an electrical power supply to provide an excitation current for the windings (201). 2) Method (400) according to claim 1, wherein the method (400) subsequently comprises, in addition to the potting (402), arranging a rotor shaft (202) in a central recess (123) of the rotor body (122). 3) Method (400) according to claim 2, wherein - the connection (403) of the winding interface (170) is carried out following the arrangement of the rotor shaft (202); or - the connection (403) of the winding interface (170) takes place during the arrangement of the rotor shaft (202). 4) Method (400) according to one of claims 2 to 3, wherein - the winding interface (170) is arranged on a first end face (128) of the rotor body (122); and - the rotor shaft (202) is arranged from the opposite second end face (129) of the rotor body (122) in the central recess (123) of the rotor body (122). 5) Method (400) according to one of the preceding claims, wherein - the method (400) prior to casting (402) the rotor body (122) comprises arranging a support body (210) on each of both End faces (128, 129) of the rotor body (122); wherein the support bodies (210) each cover a winding head arranged on the respective end face (128, 129); and - as part of the potting process (402), the potting compound is introduced in particular through one or more recesses (215) in one or both support bodies (210) into rotor grooves (125) and / or into a cavity between the support bodies (210) and the respective end face (128, 129) of the rotor body (122). 6) Method (400) according to claim 5, wherein the winding interface (170) extends in axial direction beyond the support body (210) on one of the two end faces (128, 129) of the rotor body (122) and thus remains freely accessible. 7) Method (400) according to one of the preceding claims, wherein the electrical power supply comprises an electronic circuit for wireless, in particular inductive, transmission of electrical energy to the windings (201) of the rotor (120). 8) Rotor component (300) for a current-excited rotor (120) of an electric machine (100), wherein - the rotor component (300) comprises a rotor body (122) with electrically conductive windings (201); - the rotor body (122) is encased in a potting compound in such a way that an electrically conductive winding interface (170) to the windings (201) remains accessible; and - the rotor component (300) is designed such that an electrical power supply for providing an excitation current for the windings (201) can be connected to the winding interface (170) following the potting of the rotor body (122) with potting compound. 9) Rotor component (300) according to claim 8, wherein the rotor component (300) is configured such that a rotor shaft (202) of the rotor (120) is subsequently the rotor body (122) can be arranged by potting the rotor body (122) with potting compound in a central recess (123) of the rotor body (122). 10) Rotor component (300) according to one of claims 8 to 9, wherein - the winding interface (170) comprises an electrically conductive contact element (171), in particular a fork, projecting in an axial direction beyond an end face (128, 129) of the rotor body (122); and / or - the winding interface (170) is electrically connected to the windings (201); and / or - the winding interface (170) is located on the rotor body (122) and / or does not touch a rotor shaft (202) of the rotor (120); and / or - the winding interface (170) is located on an electrical power transmission path to provide the excitation current at a point between the rotor shaft (202) of the rotor (120) and the windings (201).

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