Rotor for an electric machine, method for producing a rotor, and electric machine having a rotor of this kind

Abstract

The present invention relates to a rotor (1) for an electric machine (2) having a rotor body (4) that has a laminated core (6) with rotor teeth (7) that delimit longitudinal slots (9) between them. The rotor (1) has a rotor winding (10) that is arranged on the rotor teeth (7) and is composed of at least one electrical conductor that is guided around the rotor teeth (7), wherein the rotor winding (10) has winding longitudinal sections (12a, 12b) that are arranged in the longitudinal slots (9). Slot closure wedges (16) are provided in the longitudinal slots (9), each of said slot closure wedges having at least one through-opening (17a, 17b) that passes axially through a respective slot closure wedge (16), which through-openings form cooling channels (15a, 15b), through which coolant can flow, for cooling the winding longitudinal sections (12a, 12b). It is essential to the invention that the through-openings (17a, 17b) are moulded into the slot closure wedges (16) by casting. The invention furthermore relates to a method for producing a rotor (1) for an electric machine (2) and to an electric machine (2) having a rotor (1) of this kind.

Description

[0001] Rotor for an electrical machine, method for producing a rotor and electrical machine with such a rotor

[0002] The present invention relates to a rotor for an electrical machine according to the preamble of claim 1. The invention relates in particular to a method for producing a rotor and, more particularly, to an electrical machine having such a rotor.

[0003] A rotor for an electrical machine of the type mentioned above is known from DE 10 2018 220 810 A1. The known rotor has a rotor body comprising a laminated core with rotor teeth projecting radially away from the center of rotation, with longitudinal grooves filled with potting compound between adjacent rotor teeth. Cooling channels are arranged in the potting compounds, allowing direct cooling of the rotor windings. Unfortunately, the cooling channels can only be manufactured with comparatively high effort, which makes the provision of the known rotor relatively cost-intensive.

[0004] Further rotors for electrical machines are described in the documents EP 1 430 585 A1 , DE 102018220 810 A1 , EP 2 985 885 A1 , US 8,138,642 B2, DE 102018222 469 A1 or DE 10 2011 052 085 A1.

[0005] The object of the invention is to provide an improved or at least a different embodiment of a rotor for an electrical machine. The rotor according to the invention should, in particular, be relatively cost-effective to manufacture. Furthermore, an advantageous manufacturing method for such a rotor and an electrical machine with such a rotor should be specified.

[0006] In the present invention, this object is achieved by the subject matter of the independent claims. Advantageous embodiments are the subject matter of the dependent claims and the description.

[0007] The basic idea of ​​the invention is to produce the cooling channels provided in the longitudinal slots of the rotor for cooling the longitudinal winding sections of the rotor winding of the rotor by casting technology, ie in particular by a primary forming process.

[0008] Accordingly, a rotor for an electric machine is proposed, which is equipped with a rotor body defining a rotational center axis and has a laminated core with rotor teeth projecting radially away from the rotational center axis, which are adjacent to one another in a circumferential direction around the rotational center axis and define longitudinal grooves between them in the circumferential direction, which axially penetrate the laminated core. The rotor further has a rotor winding arranged on the rotor teeth and comprising at least one electrically conductive conductor wound in several turns around the rotor teeth. The rotor winding thus has longitudinal winding sections, each of which is arranged in the longitudinal grooves and extends axially through the longitudinal grooves, adjacent to a rotor tooth.Furthermore, it is provided that slot closure wedges, preferably formed from a hardenable, viscous potting compound, are arranged in the longitudinal slots, each of which has at least one through-opening axially penetrating a respective slot closure wedge. The through-openings form cooling channels through which coolant can flow to cool the longitudinal winding sections. Essential to the invention is that the through-openings are cast, in particular, pre-formed, into the slot closure wedges.

[0009] In other words, the cooling channels are directly defined or formed by the slot closure wedges. This eliminates the need for the pipe or hose bodies typically used to create cooling channels, which must be laboriously laid and fixed in the longitudinal slots during rotor manufacture. The proposed rotor is therefore comparatively easy to assemble and has a reduced number of components compared to conventional rotors, which is why the rotor according to the invention is relatively lightweight and cost-effective. Furthermore, the absence of pipe or hose bodies results in efficient cooling of the longitudinal winding sections of the rotor winding, since heat flows between the longitudinal winding sections of the rotor winding and a coolant flowing through the cooling channels during operation are not adversely affected by the thermal conductivity of the pipe or hose bodies.

[0010] Furthermore, it can be provided that the through-openings are incorporated into the slot closure wedges during manufacture of the rotor by encapsulating removable core elements inserted into the longitudinal slots with a potting compound that is in a hardenable, viscous state during encapsulation. Furthermore, the encapsulation can be realized with a viscous polymer material that is dimensionally stable upon hardening or cooling and is thus demoldable. The casting or primary shaping of the through-openings in the slot closure wedges is expediently realized in concrete terms by first inserting the provided core elements into the longitudinal slots during manufacture of the rotor and then encapsulating them with a potting compound that is provided in a hardenable, viscous state.The potting compound poured into the longitudinal slots wets the core elements, and in particular the longitudinal winding sections of the rotor winding, and molds the outer shape of the core elements with high contour accuracy. After a subsequent curing phase, during which the potting compound hardens, the then cured potting compound forms the said slot closure wedges, whereby the through openings are provided with an inner shape defined by the outer shape of the core elements. According to the understanding of the invention, the slot closure wedges formed from the cured potting compound are dimensionally stable and / or permanently non-detachably connected to the rotor body and / or the longitudinal winding sections of the rotor winding. The slot closure wedges can have elastic material properties.Furthermore, the slot closure wedges and / or the said core elements are expediently designed such that the core elements can be relatively easily removed from the slot closure wedges, i.e., demolded. This can be achieved, for example, by the core elements having a conical outer shape, which facilitates axial withdrawal of the core elements from the slot closure wedges. The core elements can be pulled axially out of the slot closure wedges, or expelled axially from the slot closure wedges using pressure, or removed from the slot closure wedges using a solvent; in the latter case, the core elements are implemented, for example, as salt cores. After the through-holes have been cast, the through-holes can be machined if necessary.This allows the through-openings to be provided cost-effectively and, in particular, to be arranged relatively easily in the slot closure wedges close to the rotor winding.

[0011] It can be expediently provided that the through-openings are each arranged in the circumferential direction between two adjacent longitudinal winding sections. Alternatively or additionally, it can be provided that at least one through-opening, two through-openings, or several through-openings are provided in each slot closure wedge. This allows efficient cooling of the longitudinal winding sections to be achieved by increasing the heat flow from the longitudinal winding sections of the rotor winding to be cooled to the coolant.

[0012] In particular, it can be provided that at least one through-opening is assigned to each longitudinal winding section such that a longitudinal winding section is in greater heat exchange with a coolant that flows during operation through the at least one through-opening assigned to this longitudinal winding section than with a coolant that flows during operation through at least one further through-opening assigned to a further longitudinal winding section adjacent to this longitudinal winding section. Said through-opening and said further through-opening can be arranged in a single slot closure wedge.The assignment of the through-openings to the longitudinal winding sections can be designed such that the distance between a longitudinal winding section and at least one through-opening assigned to this longitudinal winding section is smaller than the distance between a further longitudinal winding section adjacent to this longitudinal winding section and at least one through-opening assigned to this further longitudinal winding section. This has the overall advantage of significantly improving the cooling of the longitudinal winding sections of the rotor winding, since the heat flow from the longitudinal winding sections of the rotor winding to be cooled to the coolant flowing through the cooling channels during operation is increased.

[0013] It can further be provided that the through-openings are delimited, in particular exclusively, by a respective slot closure wedge. As a result, the through-openings or the cooling channels are completely embedded in a respective slot closure wedge. This achieves, in particular, electrical insulation of the coolant flowing through a through-opening or cooling channel during operation from the rotor winding. Further measures for sealing the through-openings or the cooling channels within the longitudinal slots can therefore be dispensed with.

[0014] Furthermore, it can be provided that at least one through-opening is assigned to each longitudinal winding section, wherein an axially extending separating element is arranged in the circumferential direction between a longitudinal winding section and a through-opening assigned to this longitudinal winding section. In other words, the through-openings and the longitudinal winding sections of the rotor winding are each connected to one another or spaced apart from one another via a separating element. The separating elements can each abut a longitudinal winding section and / or a through-opening.

[0015] It can further be provided that the separating elements arranged in a longitudinal slot, for example two separating elements, are designed separately. Alternatively, it can be provided that the separating elements arranged in a longitudinal slot, for example two separating elements, are designed as an integral, i.e. one-piece, separating component, wherein the separating component has through-openings. The separating component can have supports on both longitudinal winding sections. Furthermore, the through-openings of the separating component are expediently designed such that the potting compound used to produce the slot closure wedges can flow through the through-openings. This can ensure that the longitudinal slots are completely filled with potting compound. Furthermore, it can be provided that the separating elements are each axially, i.e.parallel to the rotation center axis, extend in sections or completely over the entire axial length of a respective winding longitudinal section. Furthermore, it can be provided that the separating elements each extend in a transverse direction running transversely, in particular at right angles, to the rotation center axis, in sections or completely over the entire transverse length of a respective winding longitudinal section.

[0016] Furthermore, it can be provided that the separating elements each have an insulator layer formed by a respective slot closure wedge for electrically insulating the through-openings from the longitudinal winding sections and / or a support layer for supporting a longitudinal winding section. Furthermore, the through-openings can each be delimited in sections by a respective slot closure wedge and in sections by a respective separating element, in particular by its insulator layer and / or its support layer. The insulator layers are advantageously formed by a respective slot closure wedge having electrically insulating properties. The support layers can be formed by a strip-shaped insert body, which will be discussed below. The insulator layers and / or the support layers can be relatively thin and / or, for example, each in the form of a film or foil.Furthermore, the support layers can expediently extend beyond the through-openings in the transverse direction on both sides. Furthermore, it can be provided that an insulating layer is arranged between the longitudinal winding sections and the separating elements. The insulating layer can be formed, in particular, by a potting compound or an electrically insulating insulation layer.

[0017] The said separating elements expediently implement a supporting function in such a way that they mechanically support the longitudinal winding sections of the winding.

[0018] The inventors have further recognized that undesirable bulging of the longitudinal winding sections of the rotor winding in the circumferential direction can be counteracted by expediently supporting said support layers in contact with the longitudinal winding sections. The support layers can advantageously extend axially, i.e., parallel to the rotational center axis, in sections or completely over an overall axial longitudinal extent of a respective longitudinal winding section and / or further extend in a transverse direction running transversely to the rotational center axis, in sections or completely over an overall transverse extent of a respective longitudinal winding section. By means of this arrangement of the support layers, bulging of the longitudinal winding sections can be reliably prevented.

[0019] It can expediently be provided that said support layers are each realized by an elongated metal strip, in particular a sheet metal strip, embedded in a respective potting compound. The metal strips can each have electrical insulation, for example an electrically insulating coating. The metal strips can furthermore have two opposing large flat sides, two opposing axial end faces, and two opposing narrow sides. The first large flat side of the metal strip can be supported in contact with said longitudinal winding section. Furthermore, the second large flat side of the metal strip can partially delimit the at least one through-opening or a cooling channel and / or bear against an insulating layer.The second large flat side of the metal strip can be partially and / or the axial end faces of the metal strip and / or the narrow sides of the metal strip can each be embedded in a respective slot closure wedge, i.e. connected to this slot closure wedge.

[0020] Corresponding metal strips can be inserted into the longitudinal slots as insert bodies during the manufacture of the rotor and at least partially encapsulated by the potting compound provided in a curable, viscous state, so that, once the potting compound has cured, the metal strips are fully embedded and fixed in the respective slot closure wedges, or at least partially embedded in them. For the purposes of the invention, the term "encapsulated" can be understood to mean that at least one or more sides of a metal strip are wetted by the curable potting compound, so that, after the potting compound has cured, the metal strip is connected to the slot closure wedge via only one or more surfaces.

[0021] In principle, the metal strip can be made of any metal material. The decisive factor is that the metal material selected for the metal strip possesses a certain degree of mechanical rigidity, thus preventing undesirable bulging of the longitudinal winding sections of the rotor winding in the circumferential direction, and exhibits comparatively good thermal conductivity, allowing heat to be optimally transferred from a longitudinal winding section to a coolant flowing through the at least one cooling channel.

[0022] It can be expediently provided that the slot closure wedges are formed from a plastic material, in particular a thermosetting plastic material, for example an epoxy resin, or a thermoplastic. Thermosets with a high glass transition temperature are preferred, which cure through crosslinking and can withstand operating temperatures of 150-180°C. Thermoset injection molding is preferred for a phenol-based casting compound, or transfer molding for an epoxy-based casting compound.

[0023] The plastic material can also be advantageously formed from a thermoplastic. It can advantageously be introduced into the longitudinal slots of the rotor in a hot, liquefied state and solidify upon cooling. Suitable materials can be produced cost-effectively and, from a process engineering perspective, can be poured into the longitudinal slots of the rotor as a curable, viscous potting compound, which is relatively easy to process and subsequently cured. Slot closure wedges designed accordingly advantageously exhibit electrically insulating properties.

[0024] Further expediently, it can be provided that the slot closure wedges are cast into the longitudinal slots as a potting compound in a hardenable, viscous state, wherein the slot closure wedges are formed by hardening the potting compound, wherein the hardening of the potting compound creates positive connections between the slot closure wedges and the longitudinal winding sections arranged in a respective longitudinal slot and / or the rotor teeth delimiting a respective longitudinal slot and / or the support layers arranged in a respective longitudinal slot. As a result, the slot closure wedges are permanently and non-removably fixed to the rotor. The casting of the potting compound into the longitudinal slots can further be designed such that the slot closure wedges seal the longitudinal slots in a fluid-tight manner, so that further measures for electrical insulation of the rotor can be unnecessary.

[0025] Furthermore, it can be provided that the slot closure wedges fill a respective longitudinal slot only partially or completely. In particular, the slot closure wedges can leave a radially inner foot region of the longitudinal slots free or completely fill it. Furthermore, in the case of so-called full encapsulation, it can be provided that the slot closure wedges completely fill all gaps formed between the turns of the longitudinal winding sections. Alternatively, in the case of partial encapsulation, it can be provided that the slot closure wedges completely fill only the gaps formed between outer winding layers of the longitudinal winding sections.

[0026] The through-holes can each have a coolant-permeable cross-section that is round, oval, rectangular, polygonal, kite-shaped, or diamond-shaped. This specifies preferred through-hole cross-sections of the through-holes or cooling channels. They can be created, in particular, during the casting of the through-holes into the slot closure wedges, for which purpose core elements are expediently provided with an outer contour complementary to the desired through-hole cross-section.

[0027] In a further embodiment of the invention, the rotor teeth can have radially outer pole pieces that project beyond the longitudinal slots and the respective longitudinal winding sections arranged therein in the circumferential direction, with the slot closure wedges abutting the pole pieces. In particular, the slot closure wedges can be provided to abut partially or exclusively against radially inwardly oriented inner surfaces of the pole pieces. As a result, the slot closure wedges are supported radially outwardly on the pole pieces, thereby achieving a relatively effective and cost-effective fluid-tight sealing of the longitudinal slots or the rotor winding.

[0028] Furthermore, it can be provided that the through-openings and / or the core elements used to create the through-openings have a conical shape. A conical shape of the through-openings or the cooling channels or the core elements used to create the cooling channels facilitates the easy removal of the core elements from the cured casting compound. The conical through-openings can each have an opening angle of less than or equal to 1°, where the opening angle is understood to be an angle measured between the surface lines of a through-opening viewed in section.

[0029] In particular, it can be provided that radially outwardly oriented outer surfaces of the slot closure wedges are provided with a plastic coating. Said plastic coating can also be provided on the laminated core of the rotor body, in particular on the radially outwardly oriented top surfaces of said pole shoes. The plastic coating can be created, for example, by overmolding the outer surfaces of the slot closure wedges and / or the laminated core and / or the top surfaces of the pole shoes. As a result, the rotor has a complete or partial plastic coating, effectively and cost-effectively sealing the rotor in a fluid-tight manner.

[0030] Furthermore, it can be provided that the longitudinal slots are tightly covered by a closing element. This allows the longitudinal slots to be effectively sealed with the potting compound present during formation of the slot closure wedges or, during later operation, the slot closure wedges accommodated therein. The closing elements can, for example, be arranged radially outwardly on the pole shoes of the rotor teeth. The term “radial” refers here to the center of rotation of the rotor. The closing element can, for example, be realized in the form of a separate component, in particular a plastic component, pressed into the slot closure wedges. The pressed-in component can be arranged between the rotor teeth, seal a respective longitudinal slot and / or delimit the respective longitudinal slot to the outside. The pressed-in component can additionally be overmolded. The pressed-in component can be realized by overmolded injection molding of the slot closure wedges.Alternatively or in addition to the closure element, it may be expedient if the longitudinal grooves are tightly covered during the manufacture of the rotor and the groove closure wedges by means of a sliding tool, in particular a casting tool and / or a casting mold that does not remain on the workpiece.

[0031] It can further be provided that in the proposed rotor and / or its manufacture, the rotor winding, in particular the longitudinal winding sections of the rotor winding, are or will first be cast using a curable potting compound in a viscous state. By potting the rotor winding with potting compound, cavities located between the turns of the rotor winding are filled. Removable core elements inserted into the longitudinal slots can then be cast with the same potting compound, forming the through-openings in the slot closure wedges. This effectively achieves a joint or successive potting process, whereby cavities in the rotor winding are first filled using the same potting compound and then the through-openings in the slot closure wedges are formed.It may be advantageous if, during the manufacture of the rotor, the potting of the rotor winding and the creation of the through-openings in the slot closure wedges with the removable core elements inserted into the longitudinal slots are carried out with the same potting compound and in a single work step.

[0032] According to a further basic concept of the invention, a method for producing a rotor for an electric machine is provided. The method includes the following steps:

[0033] - Providing a rotor blank having a rotor body defining a rotational center axis, which has a laminated core with a plurality of rotor teeth projecting radially away from the rotational center axis, which are adjacent to one another in a circumferential direction around the rotational center axis and define longitudinal grooves between them in the circumferential direction, which axially penetrate the laminated core,

[0034] - Providing an energizable rotor winding on the rotor blank, wherein the rotor winding is provided from at least one electrically conductive conductor guided in several turns around the rotor teeth, wherein the rotor winding is provided with winding longitudinal sections which are arranged in the longitudinal slots and extend axially through the longitudinal slots in contact with a rotor tooth,

[0035] - Providing core elements which are intended to create cooling channels of the rotor for cooling the winding longitudinal sections, through which coolant can flow, and which have an outer shape which defines an inner shape of the cooling channels,

[0036] - optional insertion of metal strips into the longitudinal grooves,

[0037] - Inserting the core elements into the longitudinal grooves,

[0038] - Filling the longitudinal grooves with a casting compound by pouring the casting compound into the longitudinal grooves in a hardenable, viscous state so that the longitudinal grooves are partially or completely filled with casting compound and the inserted core elements are wetted by casting compound and / or the optional metal strips are wetted by casting compound,

[0039] - Curing of the casting compound, optionally without cooling, and after curing the casting compound forms dimensionally stable slot closure wedges,

[0040] - Removing the core elements, creating through-openings that form the cooling channels through which coolant can flow to cool the longitudinal winding sections. This provides a method for producing an advantageous rotor for an electrical machine, in particular a method for producing the rotor according to the preceding description. The through-openings or the cooling channels can have the features described above in connection with the rotor. Furthermore, the metal strips can have the features described above in connection with the separating elements of the rotor.

[0041] According to a further basic concept of the invention, an electrical machine, in particular a generator or a drive motor, is proposed, which has a rotor according to the preceding description or a rotor manufactured according to the preceding method. This provides an advantageous electrical machine characterized by a relatively lightweight and cost-effective rotor.

[0042] In summary, the present invention preferably relates to a rotor for an electrical machine with a rotor body having a laminated core with rotor teeth defining longitudinal slots between them. The rotor has a rotor winding arranged on the rotor teeth, comprising at least one electrical conductor guided around the rotor teeth, wherein the rotor winding has longitudinal winding sections arranged in the longitudinal slots. Slot closure wedges are provided in the longitudinal slots, each of which has at least one through-opening axially penetrating a respective slot closure wedge, which form cooling channels through which coolant can flow to cool the longitudinal winding sections. It is essential to the invention that the through-openings are cast into the slot closure wedges.The invention further relates to a method for producing a rotor for an electrical machine and to an electrical machine comprising such a rotor. Further important features and advantages of the invention emerge from the subclaims, the drawings, and the associated description of the figures with reference to the drawings.

[0043] It is understood that the features mentioned above and those to be explained below can be used not only in the combination specified in each case, but also in other combinations or on their own, without departing from the scope of the present invention.

[0044] Preferred embodiments of the invention are illustrated in the drawings and are explained in more detail in the following description, wherein the same reference numerals refer to the same or similar or functionally identical components.

[0045] They show, schematically

[0046] Fig. 1 shows a sectional view of a section of a rotor for an electrical machine according to a first preferred embodiment,

[0047] Fig. 2 shows a sectional view of a section of a rotor for an electrical machine according to a further preferred embodiment and

[0048] Fig. 3 shows a section of a rotor for an electrical machine according to a further preferred embodiment in a sectional view, Fig. 4 shows a section of a rotor for an electrical machine according to a further preferred embodiment in a sectional view.

[0049] 1 to 4 each show a preferred embodiment of a rotor, designated overall by the reference numeral 1, for an electric machine 2. The electric machine 2 can be designed as a generator or as a drive motor, in particular as a traction drive for an electric vehicle (not illustrated).

[0050] Fig. 1 shows a sectional view of a section of a rotor 1 for an electrical machine 2. The rotor 1 initially has a usually approximately circular-cylindrical rotor body 4 which defines a center axis of rotation 3, around which the rotor 1 is rotationally adjustable in a circumferential direction 8 indicated by an arrow in Figs. 1 to 3. The rotor body 4 has a rotor shaft (not illustrated here) aligned coaxially with the center axis of rotation 3, and a laminated core 6 arranged on the rotor shaft in a rotationally fixed manner and having a plurality of rotor teeth 7 projecting radially away from the center axis of rotation 3. The laminated core 6 consists purely by way of example of a plurality of laminated elements made of a ferromagnetic material which are not visible in the present figures and are stacked axially one on top of the other in the direction of the center axis of rotation 3.

[0051] In Fig. 1, it can also be seen that two rotor teeth 7 directly adjacent to one another in the circumferential direction 8 define an approximately V-shaped longitudinal groove 9 between them in the circumferential direction 8, which extends completely axially through the laminated core 6. The rotor teeth 7 also have pole shoes 27 on the radial outside, each of which has a head surface 29 on the radial outside and which project at least partially beyond the longitudinal grooves 9 in the circumferential direction 8, so that they each form inner surfaces 28 facing the longitudinal grooves 9 and oriented radially inward towards the center axis of rotation 3.

[0052] The rotor 1 further comprises a rotor winding 10 which can be energized by means of a power source (not shown), which is realized from at least one electrically conductive conductor. The at least one electrically conductive conductor can have an insulating coating in order to prevent faulty electrical contact. Furthermore, it is provided that the at least one electrically conductive conductor of the rotor winding 10 is guided in a conventional manner in several turns around the rotor teeth 7. The rotor winding 10 has winding heads (also not shown) on axially opposite, not illustrated axial end faces of the rotor teeth 7, to which longitudinal winding sections 12a, 12b of the rotor winding 10 are connected axially, in this case parallel to the rotational center axis 3. Two of these

[0053] Longitudinal winding sections 12a, 12b of the rotor winding 10 are, as can be seen in Figs. 1 to 3, accommodated within a longitudinal groove 9 and are arranged at least in sections and optionally exclusively on circumferential surfaces 13 of the directly adjacent rotor teeth 7, which are opposite one another in the circumferential direction 8. The longitudinal winding sections 12a, 12b of the rotor winding 10 bear, for example, directly or indirectly against the circumferential surfaces 13 of the rotor teeth 7 and each extend radially with respect to the center axis of rotation 3 between one of the said inner surfaces 28 of the pole shoes 27 and a radially outwardly oriented base surface 14 of the rotor body 4, which connects circumferential surfaces 13 of a longitudinal groove 9, which are opposite one another in the circumferential direction 8. In this case, a respective winding longitudinal section 12a, 12b can rest on the inner surface 28 of a pole shoe 27 and / or a base surface 14 of the rotor body 4.

[0054] During normal operation of the rotor 1, losses in the form of waste heat occur within the rotor winding 10, which cause undesired heating of the rotor winding 10 and the adjacent components of the rotor 1, in particular the rotor body 4.

[0055] In order to prevent overheating of the rotor 1 during normal operation, which could in particular cause the aforementioned insulation coating of the electrically conductive conductor to thermally fail and cause a failure of the electrical machine 2, it is provided that the rotor 1 is equipped with a cooling device 14 which has cooling channels 15a, 15b through which coolant can flow for cooling the longitudinal winding sections 12a, 12b.

[0056] In known rotors, cooling channels result in relatively high provision costs, which is undesirable. Therefore, it is proposed here that slot closure wedges 16 be arranged in the longitudinal slots 9 of the rotor 1, each of which has at least one through-opening 17a, 17b axially penetrating a respective slot closure wedge 16. The through-openings 17a, 17b form the cooling channels 15a, 15b through which coolant can flow for cooling the longitudinal winding sections 12a, 12b. The rotor 1 according to the present invention can be provided cost-effectively by molding the through-openings 17a, 17b into the slot closure wedges 16 by casting, in particular by primary molding.

[0057] This eliminates the need for the pipes or hoses typically used to create cooling channels, which previously required laborious installation and installation in the longitudinal grooves 9. The proposed rotor 1 is therefore comparatively easy to assemble and has a reduced number of components, making it more cost-effective than conventional rotors. Furthermore, the absence of pipes or hoses enables efficient cooling of the longitudinal winding sections 12a, 12b of the rotor winding 10, since heat flows between the longitudinal winding sections 12a, 12b of the rotor winding 10 and a coolant flowing through the cooling channels 15a, 15b during operation are not adversely affected by the thermal conductivity of the pipes or hoses.

[0058] The casting or primary forming of the through-openings 17a, 17b in the slot closure wedges 16 is realized in particular by providing core elements (not illustrated here) and first inserting them into the longitudinal slots 9 during the manufacture of the rotor 1. These elements are then encapsulated with a polymeric (thermoplastic or thermosetting) potting compound (also not illustrated here). The potting material fills a cavity created between the winding sections 12a, 12b of the rotor winding 10 and the core elements inserted into the longitudinal slots 9 and encloses the core elements so that their shape forms continuous channels after demolding.After a cooling or curing phase following the casting process, the casting compound forms the aforementioned slot closure wedges 16, with the through-openings 17a, 17b being provided with an inner shape defined by the outer shape of the core elements, for example, a conical one. Finally, the core elements are removed from the slot closure wedges 16, i.e., demolded.

[0059] In the embodiment of the rotor 1 illustrated in Fig. 1, it is provided that each slot closure wedge 16 has exactly one single central through-opening 17a, which is arranged centrally in the circumferential direction 8 between two adjacent winding longitudinal sections 12a, 12b.

[0060] In contrast, in the embodiments of the rotor 1 illustrated in Figs. 2 and 3, exactly two separate through-openings 17a, 17b are provided in each slot closure wedge 16, each of which is arranged in the circumferential direction 8 between two adjacent longitudinal winding sections 12a, 12b. Other configurations with more than two through-openings or cooling channels are also conceivable. In Figs. 2 and 3 it can also be seen that each longitudinal winding section 12a, 12b is assigned exactly one through-opening 17a, 17b such that the first longitudinal winding section 12a is in a greater heat exchange with a coolant which, during operation, flows through the through-opening 17a assigned to this first longitudinal winding section 12a than with a coolant which, during operation, flows through the further through-opening 17b assigned to the second longitudinal winding section 12b adjacent to the first longitudinal winding section 12a.

[0061] Furthermore, it should be mentioned that in Fig. 1 the through openings 17a are limited exclusively by a respective slot closure wedge 16, ie the through openings 17a or the cooling channels 15a according to this embodiment are each completely embedded in a respective slot closure wedge 16.

[0062] 1 to 3 further show that separating elements 18 are arranged in the circumferential direction 8 between the longitudinal winding sections 12a, 12b and the through openings 17a, 17b assigned to these longitudinal winding sections 12a, 12b. The separating elements 18 each extend axially, i.e. parallel to the rotational center axis 3, in sections or completely over an overall axial longitudinal extent of a respective longitudinal winding section 12a, 12b and furthermore in each case in a transverse direction 19 running transversely, in particular at right angles, to the rotational center axis 3, in sections over an overall transverse extent of a respective longitudinal winding section 12a, 12b. It is further provided that the separating elements 18 are each formed by an insulator layer 21 according to the embodiments illustrated in Figs. 1 and 2.The insulator layers 21 are provided for electrically insulating the through-openings 17a, 17b from the longitudinal winding sections 12a, 12b and are formed by a respective slot closure wedge 16. This means that the insulator layers 21 are each an integral component of the slot closure wedges 16. The insulator layers 21 directly delimit the through-openings 17a, 17b in sections, whereby an inner side of the insulator layers 21 facing the through-openings 17a, 17b is wetted by coolant during operation.

[0063] In the embodiment illustrated in Fig. 3, in contrast to the embodiments presented in Figs. 1 and 2, the separating elements 18 comprise an insulator layer 21 and additionally a support layer 22, wherein the insulator layer 21 again serves to electrically insulate the through-openings 17a, 17b from the longitudinal winding sections 12a, 12b and is formed by a respective slot closure wedge 16. The support layers 22 are each formed by an elongated metal strip 23 arranged directly on an insulator layer 21 and inserted into the longitudinal slots 9 as an insert during the manufacture of the rotor 1. In the present case, it is also provided that the support layers 22 or the metal strips 23 of the separating elements 18 are each supported in contact with a winding longitudinal section 12a, 12b, whereby an undesirable bulging of the winding longitudinal section 12a, 12b can be prevented.The support layers 22 primarily fulfill a mechanical function, namely supporting the rotor winding 10.

[0064] In Figs. 1 to 3 it can also be seen that the through-openings 17a, 17b each have a cross-section 26 through which coolant can flow during operation, wherein a cross-section 26 according to the embodiment illustrated in Fig. 1 is kite-shaped and the cross-sections 26 according to the embodiments illustrated in Figs. 2 and 3 are rectangular.

[0065] Furthermore, it should be mentioned that the pole shoes 27 of the rotor teeth 7 project beyond the longitudinal slots 9 and the longitudinal winding sections 12a, 12b in the circumferential direction 8, so that the pole shoes 27 have the above-mentioned radially inwardly oriented inner surfaces 28. In the embodiments illustrated in Figs. 1 to 3, the slot closure wedges 16 are applied in a fluid-tight manner to the inner surfaces 28 of the pole shoes 27, thereby achieving an effective and at the same time cost-effective fluid-tight sealing of the longitudinal slots 9 and the rotor winding 10.

[0066] In addition, it can be provided that the head surfaces 29 of the pole shoes 27 and / or radially outwardly oriented outer surfaces 30 of the slot closure wedges 16 are covered with a plastic coating not shown in Figs. 1 to 3.

[0067] The embodiment illustrated in Fig. 4 differs from the previous embodiments in that the longitudinal slots 9 are tightly covered radially outwardly by a closure element 70. This effectively seals the longitudinal slots 9 and the slot closure wedges 16 accommodated therein. In particular, Fig. 4 shows that the closure elements 70 are applied to both sides of the pole pieces 27. Furthermore, the closure element 70 is clearly implemented as a separate component, in particular a plastic component. The closure element 70 can also be overmolded.

[0068] *****

Claims

Claims 1 . Rotor (1 ) for an electrical machine (2), - with a rotor body (4) defining a rotational center axis (3) and having a laminated core (6) with rotor teeth (7) projecting radially away from the rotational center axis (3), which are adjacent to one another in a circumferential direction (8) around the rotational center axis (3) and delimit longitudinal grooves (9) between them in the circumferential direction (8) which axially penetrate the laminated core (6), - with a rotor winding (10) arranged on the rotor teeth (7) and capable of being supplied with current, comprising at least one electrically conductive conductor wound in several turns around the rotor teeth (7), - wherein the rotor winding (10) has longitudinal winding sections (12a, 12b) which are each arranged in the longitudinal slots (9) and extend axially through the longitudinal slots (9) in contact with a rotor tooth (7), - wherein slot closure wedges (16) are arranged in the longitudinal grooves (9), each having at least one through-opening (17a, 17b) axially penetrating a respective slot closure wedge (16), - wherein the through-openings (17a, 17b) form cooling channels (15a, 15b) through which coolant can flow for cooling the longitudinal winding sections (12a, 12b), characterized in that - the through openings (17a, 17b) are formed into the slot closure wedges (16) by casting, in particular by primary molding.

2. Rotor (1 ) according to claim 1 , characterized in that - the through openings (17a, 17b) in the slot closure wedges (16) are produced by casting around removable core elements inserted into the longitudinal grooves (9), and / or. - the casting is carried out with a casting compound in a hardenable, viscous state, and / or - the casting is carried out with a viscous polymer material which is dimensionally stable through curing or cooling and is therefore demouldable.

3. Rotor (1) according to claim 1 or 2, characterized in that - the through openings (17a, 17b) are each arranged in the circumferential direction (8) between two adjacent winding longitudinal sections (12a, 12b), and / or - at least one, two or more through openings (17a, 17b) are provided in each slot closure wedge (16).

4. Rotor (1) according to one of the preceding claims, characterized in that - at least one through-opening (17a, 17b) is assigned to each longitudinal winding section (12a, 12b) in such a way that a longitudinal winding section (12a) is in a greater heat exchange with a coolant which, during operation, flows through the at least one through-opening (17a) assigned to this longitudinal winding section (12a) than with a coolant which, during operation, flows through at least one further through-opening (17b) assigned to a further longitudinal winding section (12b) adjacent to this longitudinal winding section (12a).

5. Rotor (1) according to one of the preceding claims, characterized in that - the through openings (17a, 17b) are delimited, in particular exclusively, by a respective slot closure wedge (16).

6. Rotor (1) according to one of the preceding claims, characterized in that - each winding longitudinal section (12a, 12b) is assigned at least one through opening (17a, 17b), - an axially extending separating element (18) is arranged in the circumferential direction (8) between a winding longitudinal section (12a, 12b) and a through opening (17a, 17b) associated with this winding longitudinal section (12a, 12b).

7. Rotor (1) according to claim 6, characterized in that - the separating elements (18) arranged in a longitudinal groove (9) are designed separately, or - the separating elements (18) arranged in a longitudinal groove (9) are designed as an integral separating component with through openings.

8. Rotor (1) according to claim 6 or 7, characterized in that - the separating elements (18) each extend axially in sections or completely over an overall axial length of a respective winding longitudinal section (12a, 12b), and / or - the separating elements (18) each extend in a transverse direction (19) running transversely to the rotational center axis (3), in sections or completely over an overall transverse extent of a respective longitudinal winding section (12a, 12b).

9. Rotor (1) according to one of claims 6 to 8, characterized in that - the separating elements (18) each have an insulating layer (21) formed by a respective slot closure wedge (16) for electrical insulation of the Through openings (17a, 17b) opposite the winding longitudinal sections (12a, 12b) and / or a support layer (22) for supporting a winding longitudinal section (12a, 12b), and / or - the through openings (17a, 17b) are delimited in sections by a respective slot closure wedge (16) and in sections by a respective separating element (18), in particular by its insulating layer (21) and / or its supporting layer (22), and / or - an insulator layer (21) is provided between the longitudinal winding sections (12a, 12b) and the separating elements (18), wherein the insulator layer (21) is formed in particular by a casting compound or by an electrically insulating insulation layer.

10. Rotor (1) according to claim 9, characterized in that - the support layers (22) are supported in contact with the longitudinal winding sections (12a, 12b).

11. Rotor (1 ) according to claim 9 or 10, characterized in that - the support layers (22) are each realized by a metal strip (23), in particular a sheet metal strip, embedded in a respective slot closure wedge (16).

12. Rotor (1) according to one of the preceding claims, characterized in that - the through-openings (17a, 17b) each have a cross-section (26) through which coolant can flow, which is round, oval, rectangular, polygonal, kite-shaped or diamond-shaped.

13. Rotor (1) according to one of the preceding claims, characterized in that - the through openings (17a, 17b) have a conical shape, and / or - the slot closure wedges (16) are formed from a plastic material, in particular a thermosetting plastic material or a thermoplastic.

14. Rotor (1) according to one of the preceding claims, characterized in that - radially outwardly oriented outer surfaces (30) of the slot closure wedges (16) are provided with a plastic coating.

15. Rotor (1) according to one of the preceding claims, characterized in that - the longitudinal grooves (9) are tightly covered by a closure element (70), and / or - the longitudinal grooves (9) are temporarily sealed during the manufacture of the rotor (1) by means of a sliding tool, in particular a casting tool and / or a casting mold.

16. Rotor (1) according to one of the preceding claims, characterized in that - the rotor winding (10), in particular the winding longitudinal sections (12a, 12b), are cast by means of a curable casting compound in a viscous state, and removable core elements inserted into the longitudinal slots (9) are cast with the same casting compound to form the Through openings (17a, 17b) are cast in the slot closure wedges (16).

17. Method for producing a rotor (1) for an electrical machine (2) in the frame thereof - a rotor blank is provided which has a rotor body (4) defining a rotational center axis (3), which has a laminated core (6) with a plurality of rotor teeth (7) projecting radially away from the rotational center axis (3), which are adjacent to one another in a circumferential direction (8) around the rotational center axis (3) and delimit longitudinal grooves (9) between them in the circumferential direction (8) which axially penetrate the laminated core (6), - an energizable rotor winding (10) comprising at least one electrically conductive conductor guided in several turns around the rotor teeth (7) is provided on the rotor blank, wherein the rotor winding (10) is provided with longitudinal winding sections (12a, 12b) which are arranged in the longitudinal grooves (9) and extend axially through the longitudinal grooves (9) in contact with a rotor tooth (7), - wherein, for the production of cooling channels (15a, 15b) of the rotor (1) through which coolant can flow, which are provided for cooling the longitudinal winding sections (12a, 12b), core elements are provided which have an outer shape which predetermines the inner shape of the cooling channels (15a, 15b), - Inserting the core elements into the longitudinal grooves (9), - filling the longitudinal grooves (9) with a casting compound by pouring the casting compound into the longitudinal grooves (9) in a hardenable, viscous state, so that the longitudinal grooves (9) are partially or completely filled with casting compound and the inserted core elements are wetted by the casting compound, - hardening of the casting compound, whereby the casting compound forms dimensionally stable slot closure wedges (16) after hardening, - removing the core elements, whereby through openings (17a, 17b) are created which form the cooling channels (15a, 15b) through which coolant can flow for cooling the longitudinal winding sections (12a, 12b).

18. Electrical machine (2), in particular a generator or a drive motor, comprising a rotor (1) according to one of the preceding claims 1 to 16 or comprising a rotor (1) produced according to method claim 17. *****

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