End-face cover element for a rotor

Abstract

A cover element for a rotor of an electric machine is described. The cover element is designed to cover a winding head arranged on an end face of the rotor body of the rotor. The cover element comprises a support part and a cooling channel part, the cooling channel part being designed to be arranged between the winding head and the support part, and the cooling channel part being made of an electrically insulating material. The cooling channel part has at least one cooling channel which runs from an inlet opening for cooling fluid, in the radial direction as far as an outlet opening for cooling fluid, said inlet opening facing the rotor shaft of the rotor and said outlet opening facing away from the rotor shaft.

Description

[0001] 24-1370

[0002] Front cover element for a rotor

[0003] The invention relates to an electric machine, such as a (current-excited) synchronous machine. In particular, the invention relates to a voice-side cover element for covering an end face of a rotor.

[0004] 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 heads 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, the windings being supported by a support disk arranged at each end face. A cover element can be attached to each end face to cover the respective winding head, in particular by screwing it on. 24-1370

[0005] - 2 -

[0006] This document addresses the technical challenge of providing a particularly efficient cover element for covering and cooling an end face of a rotor.

[0007] The problem is solved by the independent claim. 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 itself 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. This applies equally to technical teachings described in the description, which can constitute an invention independent of the features of the independent claims.

[0008] According to one aspect, a cover element for the rotor of an electric machine is described. The cover element is designed to cover the winding head located on an end face of the rotor body. The cover element can be arranged essentially perpendicular to the rotor shaft (i.e., in the axial direction). The rotor can furthermore have a bandage that surrounds the winding head in the circumferential direction.

[0009] The cover element comprises a support part and a cooling channel part, the cooling channel part being designed (in the installed state of the cover element) to be positioned between the winding head and the support part. The cooling channel part preferably consists of an electrically insulating material (e.g., a plastic). The cooling channel part can be manufactured as a single injection-molded part 24-1370

[0010] - 3 - be designed. On the other hand, the support part preferably consists of a metal, in particular a metal sheet.

[0011] The cooling channel part has at least one cooling channel that extends radially from an inlet opening for cooling fluid (especially oil) facing the rotor shaft of the rotor to an outlet opening for cooling fluid facing away from the rotor shaft.

[0012] This describes a cover element that enables efficient and reliable cooling of the windings, especially the winding head, of a rotor.

[0013] The at least one cooling channel of the cover element preferably runs in a meandering pattern from the inlet opening to the outlet opening. Alternatively or additionally, the at least one cooling channel preferably covers 20% or more of the total surface area of ​​the end face of the rotor body. Alternatively or additionally, the cooling channel section can have several cooling channels, e.g., three or more cooling channels, each extending from an inlet opening to an outlet opening. This enables particularly efficient and reliable cooling of the windings, especially the winding head, of the rotor.

[0014] The support element can cover the cooling channel, allowing the cooling fluid flowing through the channel to contact the support element. In other words, the support element can form at least one wall of the cooling channel. This enables particularly efficient and reliable cooling of the windings, especially the winding head and the rotor.

[0015] The at least one cooling channel is preferably designed such that the cooling fluid, in particular alone, is moved from the inlet opening to the outlet opening by the centrifugal force acting during rotation of the rotor. Thus, a particularly effective 24-1370

[0016] - 4 - efficient and reliable cooling of the windings, especially the winding head and rotor, is enabled.

[0017] The outlet of at least one cooling channel can be designed such that the centrifugal force acting during rotor rotation ejects cooling fluid radially from the cooling channel. This enables particularly efficient and reliable cooling of the rotor and the stator (enclosing the rotor) of the electric machine.

[0018] The outlet opening can be efficiently formed by a recess in the support part, in particular on the outer edge of the support part facing away from the rotor shaft.

[0019] The inlet opening of the cooling channel can be designed such that, in the installed state of the cover element, the inlet opening faces a radial bore of the hollow rotor shaft (and is aligned with it in the radial direction), allowing cooling fluid to flow from the rotor shaft through the radial bore and the inlet opening into the cooling channel of the cover element's cooling channel section. This ensures that at least one cooling channel of the cover element is supplied with cooling fluid in a particularly reliable and efficient manner.

[0020] The cover element can have N bores through the support part and through the cooling channel part, which allow the cover element to be fastened to the end face of the rotor body by means of N axially extending screws, with N > 2, in particular N > 3. The cooling channel part can have N sleeves for the corresponding N screws on its rear side facing the winding head, the sleeves each extending axially from the rear of the cooling channel part to the end face of the rotor body. The N sleeves are preferably fixedly connected to the cooling channel part of the cover element. The N screws can be inserted into corresponding N 24-1370

[0021] - 5 -

[0022] Threaded holes are drilled into the end face of the rotor body. The N threaded holes can be arranged in a star-shaped disk located on the end face of the rotor body. By providing N holes for N screws, a particularly reliable and robust axial fixation of the cover element can be achieved.

[0023] According to another aspect, a rotor for an electric machine, in particular for a (current-excited) synchronous machine, is described. The rotor comprises a rotor body, which typically has a plurality of rotor slots, each extending axially from a first end face to an opposite second end face of the rotor body. The rotor body can have, for example, four or more, or six or more rotor slots. The individual rotor slots can each be arranged between two salient poles of the rotor body. The individual salient poles can extend radially from the yoke of the rotor body away from the yoke. A central recess for the rotor shaft can be arranged in the yoke of the rotor body. The rotor shaft extends axially.

[0024] The rotor can have a first star disk abutting the first end face and a second star disk abutting the second end face, each star disk having N threaded bores, with N > 2, in particular N > 3 or N > 6. Each star disk can have a yoke area that abuts the yoke of the rotor body. Furthermore, the stem disks for the individual limb poles of the rotor body can each have a leg area, the leg areas extending radially away from the yoke area of ​​the respective star disk.

[0025] The rotor further comprises electrically conductive windings, typically arranged in the rotor heads, each forming a winding head at the respective end face, in particular at the respective stem disk. 24-1370

[0026] - 6 -

[0027] Furthermore, the rotor comprises at least one cover element, designed as described in this document, which covers the winding head located on the first end face or the second end face. In particular, the rotor may have a cover element on each of its two end faces, each covering the respective winding head.

[0028] In a preferred example, the one or more cover elements each have a number of outlet openings for cooling fluid corresponding to the number of rotor slots. This ensures particularly reliable cooling of the rotor.

[0029] 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.

[0030] 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.

[0031] It should be noted that the devices and systems described in this document can be used both alone and in combination with other devices and systems described in this document. Furthermore, any aspect of the 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. 24-1370

[0032] - 7 -

[0033] The invention will now be described in more detail using exemplary embodiments.

[0034] Figure a is an exemplary electrical machine;

[0035] Figure 1b shows a perspective view of an exemplary rotor body;

[0036] Figure 1c shows a perspective view of an exemplary slotted locking wedge;

[0037] Figure 2a shows a perspective view of an exemplary rotor with rotor windings;

[0038] Figure 2b shows an exemplary support ring;

[0039] Figure 3a shows a cover element arranged on an end face of a rotor;

[0040] Figure 3b shows a sectional view of the voice-side cover element from Fig. 3a;

[0041] Figure 4a shows an example of an end-face cover element;

[0042] Figure 4b shows a support part of a cover element;

[0043] Figure 4c shows the front side of a cooling channel part of a cover element; and Figure 4d shows the back side of the cooling channel part of a cover element.

[0044] As stated at the outset, this document deals with the efficient and reliable covering and / or cooling of an end face of a rotor of 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.

[0045] 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. 24-1370

[0046] - 8 -

[0047] 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.

[0048] 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 rotor coil (i.e., windings) 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.

[0049] The rotor body 122 has a central opening 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.

[0050] Between each pair of directly adjacent salient poles 124 of the rotor body 122, a rotomut 125 is formed, in which the windings of the adjacent salient poles 124 are arranged. A rotomut 125 extends 24-1370

[0051] - 9 - moving along the longitudinal and / or rotational axis from the first end face

[0052] 128 to the opposite second end face 129 of the rotor body 122.

[0053] The Rotomut 125 between two (circumferentially) directly adjacent 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

[0054] 129 of the rotor body 122 extends. In the direction of the longitudinal axis, the opening 126 is limited by (mutually facing) legs 131 of the pole shoes 130 of the two directly adjacent leg poles 124.

[0055] 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.

[0056] 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 at 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.

[0057] 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, which lead to damage to the 24-1370

[0058] - 10 - electric machine 100, in particular the windings 201, could lead to damage. To absorb the forces acting on the winding heads 206, a cup-shaped support ring 210 can be arranged on each end face of the rotor 120 (see Fig. 2b). The support ring 210 has a cover area 212 extending substantially parallel to the respective end face, through which the respective end face is covered 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.

[0059] The support ring 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 ring 210, can, for example, rest on bearing areas of the star disk 250 of the rotor 120 (in order to fix the support ring 210 to the rotor body 122). The star disk 250 can bear against the end face 128, 129 of the rotor body 122. The individual bearing areas can be formed by the circumferential surface of the star disk 250.

[0060] During assembly, a support ring 210 can be pushed axially onto the support areas of the respective stem disk 250 on both end faces of the rotor 120, so that the winding heads 206 on both end faces of the rotor 120 are each covered by a support ring 210 (each in the axial direction and in the radial direction).

[0061] The fixation of a support ring 210 can be achieved by an interference fit between the support ring 210 and the star washer 250, in particular between the edge region 213 of the support ring 210 and the cylindrical surface of the star washer 250. To also ensure axial fixation, the support ring 210 can be screwed into the star washer 250. For this purpose, the support ring 210, in particular the cover region 212 of the support ring 210, can be secured with one or more 24-1370

[0062] - 11 -

[0063] have bores 217 through which a screw can be guided to fix the support ring 210 to the stem plate 250.

[0064] The star disk 250 itself can be fixed to the rotor body 112 via the respective winding head 206 and / or via an interference fit between the star disk 250 and the rotor shaft 202.

[0065] The support ring 210 may be designed in multiple parts. In particular, the edge area 213 may be designed as a bandage, and the cover area 212 may be designed as a (essentially flat) cover element.

[0066] Fig. 3a shows an exemplary end-face cover element 312, designed to be arranged on the end face of a winding head 206 in order to cover the end face of the winding head 206. Furthermore, in the example shown in Fig. 3a, a circumferential bandage 313 is used to enclose the winding head 206 circumferentially, so that centrifugal forces acting in the radial direction can be absorbed by the bandage 313. The bandage 313 can extend around an outer edge of the cover element 312, so that the cover element 312 is fixed in the radial direction by the bandage 313.

[0067] The cover element 312 has bores 215 through which a screw 305 can be inserted to fix the cover element 312 axially. The individual screws 305 can be screwed into corresponding threaded bores in the stem plate 250 and / or in the end face 128, 129 of the rotor body 122 to achieve axial fixation of the cover element 312.

[0068] The cover element 312 can further have one or more openings 217 through which potting compound can be introduced into the cavity between the cover element 24-1370

[0069] - 12 -

[0070] 312 and the stem disk 250 and / or the end face 128, 129 of the rotor body 122 can be inserted to support the winding head 206.

[0071] The cover element 312 has one or more outlet openings 301 on its outer edge for cooling fluid (in particular oil) to cool the rotor 120. The cooling fluid can be guided to the rotor 120 via the rotor shaft 202, which is designed as a hollow shaft. Furthermore, the cooling fluid can be directed through one or more (radial) openings in the rotor shaft 202 into one or more cooling channels of the cover element 312. During operation of the rotor 120, the cooling fluid can be driven radially through the one or more openings in the rotor shaft 202 into the one or more cooling channels of the cover element 312 by centrifugal force.The one or more cooling channels of the cover element 312 can extend from the rotor shaft 202 to the one or more outlet openings 301 on the outer edge of the cover element 312, so that the cooling fluid is driven by centrifugal force through the one or more cooling channels of the cover element 312 and is then flung out through the one or more outlet openings 301 of the cover element 312.

[0072] As shown in Fig. 3b, the cover element 312 has a (generally flat) support part 320 that covers a cooling channel part 330 of the cover element 312. The cooling channel part 330 is arranged between the support part 320 and the winding head 206. The one or more cooling channels 333 are arranged in the cooling channel part 330. The cooling channel part 330 can be made of plastic. The support part can be made of metal, in particular sheet metal.

[0073] Fig. 4a shows the cover element 312 with the support part 320 and the cooling channel part 330 in a perspective view. Fig. 4b shows the support part 320 of the cover element 312, which has N bores 325 for the corresponding N screws 305 for axially fixing the cover element 312 (e.g., with N>2, or N>3, or N>6). Furthermore, the support part 320 has one or more openings 327 for the corresponding openings 217 for introducing potting compound.

[0074] The support element 320 has a (circular) inner edge 326 on its inner side facing the rotor shaft 202. The outer edge of the support element 320, facing away from the rotor shaft 202, can also be circular, but preferably has one or more recesses 321 for the corresponding one or more outlet openings 301 of the one or more cooling channels 333. The one or more recesses 321 can be arranged rotationally symmetrically around the rotor shaft 202. In the illustrated example, the support element 320 has six recesses 321 for corresponding six outlet openings 301.

[0075] The support element 320 can be configured as a mechanical support for the cover element 312. Furthermore, the support element 320 can be configured to cool the cooling fluid flowing through the one or more cooling channels 333 of the cooling channel part 330. For this purpose, the support element 320 can directly cover the one or more cooling channels 333, so that the cooling fluid comes into contact with the support element 320.

[0076] Fig. 4c shows the front side of the cooling channel part 330 facing the support part 320, and Fig. 4d shows the rear side of the cooling channel part 330 facing away from the support part 320 (and towards the winding head 206). The rear side of the cooling channel part 330 preferably has a shape corresponding to the winding head 206 (so that the rear side of the cooling channel part 330 and / or the one or more cooling channels 333 are arranged in the immediate vicinity of the winding head 206).

[0077] The cooling channel section 330 has one or more inlet openings 332 on its inner edge facing the rotor shaft 202, through which cooling fluid can be directed from the rotor shaft 202 into the one or more cooling channels 333 (by the centrifugal force acting on the cooling fluid). The one or more - 14 -

[0078] Cooling channels 333 can run in a meandering shape from the one or more inlet openings 332 at the inner edge to the outer edge of the cooling channel part s 330, in particular to the one or more outlet openings 331 at the outer edge of the cooling channel part s 330.

[0079] The cooling channel part 330, which consists of an electrically insulating material, is preferably arranged (on the back) in the immediate vicinity directly on the winding head 206, so that the one or more cooling channels 333 can provide particularly reliable cooling of the winding head 206 and thus of the windings 201.

[0080] The cooling channel part 330 can have N bores 335 for the corresponding N screws 305 for axially fixing the cover element 312. Furthermore, the cooling channel part 330 can have one or more openings 337 for introducing potting compound.

[0081] As can be seen in Fig. 3d, the cooling channel section 330 can have guide sleeves 336 for the corresponding screws 305. The sleeves 336 can each extend axially from the cooling channel section 330 to the end face 128, 129 of the rotor body 122. The one or more sleeves 336 enable reliable axial screw fastening of the cover element 312.

[0082] The cooling channel section 330 can be configured as a sealing element for sealing the rotor 120 with respect to potting compound, the potting compound being introduced into the cavity between the cooling channel section 330 and the end face 128, 129 of the rotor body 122 (in order to support and / or fix the windings 201 and / or the winding head 202 after the potting compound has hardened). This ensures efficient and reliable manufacturing of the rotor 120. 24-1370

[0083] - 15 -

[0084] A cover element 312 is thus described, comprising a plastic cover 330 (with sleeves 336 and / or seals), i.e., a cooling channel section, and a steel sheet 320, i.e., a support section (for strength). One or more cooling channels 333 can be integrated between the sheet 320 and the plastic cover 330, through which cooling fluid (especially oil) can flow from the rotor shaft 202 and is ejected radially outwards through slots 321 in the sheet 320. The plastic cover 330 can be positioned relatively close to the winding head 206, since the plastic cover 330 is electrically insulating and thus there is no risk of voltage jumps from the winding head 206 to the cover 330. This reduces the thermal distance between the windings 202 and the sheet 320 (i.e., the support section).

[0085] 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 devices and systems by way of example.

Claims

24-1370 - 16 - Claims 1) Cover element (312) for a rotor (120) of an electric machine (100); wherein - the cover element (312) is designed to cover a winding head (206) arranged on an end face (128, 129) of a rotor body (122) of the rotor (120); - the cover element (312) has a support part (320) and a cooling channel part (330); - the cooling channel part (330) is designed to be arranged between the winding head (206) and the support part (320); - the cooling channel part (330) consists of an electrically insulating material; and - the cooling channel part (330) has at least one cooling channel (333) which extends radially from an inlet opening (332) for cooling fluid facing the rotor shaft (202) of the rotor (120) to an outlet opening (301) for cooling fluid facing away from the rotor shaft (202). 2) Cover element (312) according to claim 1, wherein the support part (330) covers the cooling channel (333) so that cooling fluid flowing through the cooling channel (333) touches the support part (330). 3) Cover element (312) according to one of the preceding claims, wherein the at least one cooling channel (333) is designed such that cooling fluid, in particular alone, is moved from the inlet opening (332) to the outlet opening (301) by the centrifugal force acting during rotation of the rotor (120). 4) Cover element (312) according to one of the preceding claims, wherein the outlet opening (301) of the at least one cooling channel (333) is such that 24-1370 - 17 - is designed so that the centrifugal force acting during rotation of the rotor (120) causes cooling fluid to be flung out of the cooling channel (333) in a radial direction. 5) Cover element (312) according to one of the preceding claims, wherein the inlet opening (332) of the cooling channel (333) is designed such that the inlet opening (332) in the installed state of the cover element (312) faces a radial bore of the rotor shaft (202) designed as a hollow shaft, and cooling fluid from the rotor shaft (202) passes through the radial bore and through the inlet opening (332) into the cooling channel (333) of the cooling channel part s (330) of the cover element (312). 6) Cover element (312) according to one of the preceding claims, wherein the cover element (312) has N bores (217) through the support part (320) and through the cooling channel part (330) which make it possible to fasten the cover element (312) to the end face (128, 129) of the rotor body (122) by means of N axially extending screws (305), with N>2, in particular N>3. 7) Cover element (312) according to claim 6, wherein - the cooling channel part (330) has N sleeves (336) for the corresponding N screws (305) on a rear side facing the winding head (206); and - the sleeves (336) extend from the rear of the cooling channel part (330) in an axial direction to the front face (128, 129) of the rotor body (122). 8) Cover element (312) according to one of the preceding claims, wherein the outlet opening (301) is formed by a recess on the support part (320), in particular on an outer edge of the support part (320) facing away from the rotor shaft (202). 24-1370 - 18 - 9) Cover element (312) according to one of the preceding claims, wherein the support part (320) consists of a metal, in particular a metal sheet. 10) Cover element (312) according to one of the preceding claims, wherein - which at least one cooling channel (333) meanders from the inlet opening (332) to the outlet opening (301); and / or - which covers at least one cooling channel (333) 20% or more of the total area of ​​the end face (128, 129) of the rotor body (122); and / or - the cooling channel part (330) has several cooling channels (333) which each extend from an inlet opening (332) to an outlet opening (301). 11) Rotor (120) for an electric machine (100), wherein the rotor (120) comprises, - an axially extending rotor shaft (202); - a rotor body (122) with a plurality of rotomutes (125), each extending in an axial direction from a first end face (128) to an opposite second end face (129) of the rotor body (122); - electrically conductive windings (201) arranged in the rotor slots (125), each forming a winding head (206) on the first and second end faces (128, 129) of the rotor body (122); and - at least one cover element (312) which is designed according to one of the preceding claims and which covers the winding head (206) arranged on the first end face (128) or on the second end face (129). 24-1370 - 19 - 12) Rotor (120) according to claim 11, wherein the cover element (312) has a number of outlet openings (301) for cooling fluid corresponding to the number of rotor slots (125) of the rotor (120).

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