Rotor of an electric machine

Abstract

The present invention relates to a rotor (1) of an electric machine (10), comprising: a rotor body (2) extending around a rotor axis (100), in particular a laminated rotor core, having a plurality of salient poles (4), wherein a relevant rotor slot (5) is formed between every two adjacent salient poles (4); an excitation winding (6a) comprising a plurality of excitation coils (6), which each surround a relevant pole shank (4a) of one of the salient poles (4); and a rotor sleeve (7) which surrounds the rotor body (2) with respect to a circumferential direction (300) about the rotor axis (100), characterized in that, in at least one of the rotor slots (5), at least one pre-load transfer element (8) is provided which is disposed between the rotor sleeve (7) and the excitation winding (6a) in the radial direction (200) and which is designed to transfer a mechanical pre-load of the rotor sleeve (7) to the excitation winding (6a).

Description

[0001] Description

[0002] title

[0003] Rotor of an electrical machine

[0004] State of the art

[0005] The present invention relates to a rotor of an electrical machine. Furthermore, the invention relates to an electrical machine having such a rotor. The rotor has a prestressed field winding.

[0006] Electrical machines are known from the prior art that have a rotor with an excitation winding. To avoid air turbulence, the use of rotor sleeves is known. For example, DE 10 2020 130 123 A1 describes an electrical machine with a rotor, wherein the rotor has a rotor sleeve. The rotor sleeve is arranged on the rotor side of the air gap and covers, at least in the circumferential direction, given distances between the salient poles against the air gap, i.e., toward the air gap. This is particularly helpful at relatively high speeds to avoid turbulence of a medium present in the air gap—typically the air flowing around the rotor in the air gap—when the rotor rotates.

[0007] Disclosure of the invention

[0008] The rotor according to the invention allows the rotor winding to be pre-tensioned by a rotor sleeve. This prevents the rotor winding from slipping during rotor operation and enables high slot fill factors.

[0009] The rotor for an electric machine has a rotor body extending around a rotor axis and having a plurality of salient poles. A rotor slot is formed between each adjacent salient pole. The rotor body is preferably a rotor core. The rotor also has an excitation winding. This comprises a plurality of excitation coils, each of which encloses a pole shaft of one of the salient poles. Furthermore, the rotor has a rotor sleeve that surrounds the rotor body circumferentially around the rotor axis.

[0010] At least one preload transmission element is provided in at least one of the rotor slots. The preload transmission element is arranged radially between the rotor sleeve and the excitation winding and is also designed to transmit a mechanical preload of the rotor sleeve to the excitation winding. In this way, in particular, a radial preload force can be applied to the excitation winding.

[0011] The subclaims show preferred developments of the invention.

[0012] The salient poles are preferably designed without pole shoes. This allows the excitation coils to be radially mounted on the pole shafts. The excitation coils can thus be pre-wound and mounted on the pole shafts in the wound state. This simplifies the manufacture of the excitation coils. Furthermore, it is possible for excitation coils mounted on adjacent pole shafts to have only a minimal gap between them, thereby maximizing the slot fill factor. The slot fill factor is preferably above 54%, preferably above 60%. In particular, slot fill factors of up to approximately 67% are possible. Furthermore, it is provided that the bias voltage transmission element is a separate insert. The bias voltage transmission element extends in the axial direction of the rotor slot. The bias voltage transmission element can preferably be inserted into the rotor slot after the excitation windings have been mounted on the pole shafts.

[0013] Preferably, the respective preload transmission element protrudes axially from the rotor body. This ensures, in particular, that the preload is transmitted through the rotor sleeve from the preload transmission element along the entire axial dimension of the rotor slot. Furthermore, it is preferably provided that the preload transmission element is enclosed by the rotor sleeve. The rotor sleeve completely surrounds the preload transmission element in the circumferential direction. This ensures a uniform transmission of the preload force from the rotor sleeve to the preload transmission element.

[0014] Particularly advantageously, the respective preload transmission element extends radially beyond the salient poles of the respective rotor slot. This ensures that the rotor sleeve presses against the preload transmission element. This leads, in particular, to the transmission of a preload force from the rotor sleeve via the respective preload transmission elements to the excitation winding. In this way, reliable preloading of the excitation winding is achieved.

[0015] Preferably, it is also provided that the respective preload transmission element is positively fastened or anchored in the circumferential direction at its ends to the salient poles of the respective rotor slot. This is achieved in particular by clamping the preload transmission element in the circumferential direction between the salient poles of the respective rotor slot. As a result, the preload transmission element is firmly arranged within the rotor slot. Moving the preload transmission element outward is made difficult or impossible, particularly at high rotor speeds. This relieves the load on the rotor sleeve, which does not have to absorb the entire centrifugal forces emanating from the preload transmission elements.

[0016] The respective prestress transmission element comprises, in particular, lamellae embedded in a matrix. The lamellae are preferably punched. The matrix is ​​preferably made of plastic. As a result, the prestress transmission element, in particular, has low electrical conductivity and is simple and cost-effective to manufacture, as well as being robust.

[0017] In a further preferred embodiment, salient poles have pole shoes. The pole shoes each protrude into the two adjacent rotor slots with two pole collars. The pole collars of the pole shoes are each plastically bendable about an axis at the base of the respective pole collar, thereby enabling the respective excitation coil to be plugged onto the respective salient pole. Particularly advantageously, the pole collars can be plastically bent such that they are radially aligned with the pole shafts. This makes plugging in the excitation windings easy, analogous to the case where no pole shoes were present. The pole collars of the same rotor slot each form the bias voltage transmission elements. In particular, the pole collars can be bent back after the excitation windings have been plugged in, in order to extend, in particular, vertically or circumferentially from the respective pole shaft.The pole collars allow force to be transferred from the rotor sleeve to the excitation winding, which allows the excitation winding to be pretensioned.

[0018] The pole collars particularly preferably each have at least one weakened portion at their base. This weakened portion serves to reduce bending resistance, allowing the pole collars to be easily plastically deformed, particularly for attaching the winding. The weakened portion is preferably formed by a recess or indentation. This allows for the deformation of the pole collars and thus the installation of the excitation windings to be carried out easily and with minimal effort.

[0019] Preferably, the respective bias voltage transmission element is designed to be magnetically and / or electrically insulating. Alternatively, it is preferably provided that the bias voltage transmission element has no or only partial magnetic conductivity. This avoids or reduces, in particular, the risk of a magnetic or electrical short circuit between two salient poles. Any influence on the magnetic fluxes of the rotor and / or the electric machine is also minimized.

[0020] Preferably, an air gap remains within a rotor slot between two coil sides of two excitation coils. The air gap is designed, in particular, as a cooling channel. For example, in the case of a dip-impregnated winding, the gap serves as an axial cooling channel to increase continuous power. In particular, the cooling medium is introduced via a shaft and a fluid-connected rotor lamination section or a fluid-connected balancing disk.

[0021] Each excitation coil is advantageously fully or at least partially impregnated with an impregnating material. The impregnating material is, in particular, resin. Alternatively or additionally, each rotor slot is cast with a potting material, in particular resin. This particularly increases the mechanical stability of the rotor and improves the thermal properties of the rotor. The rotor sleeve preferably has a wall thickness of at least 0.5 mm, preferably at least 0.6 mm, and a maximum of 1.5 mm, preferably 1.4 mm. This leads to an optimal preload that can be applied by the rotor sleeve to the excitation winding.

[0022] The preload force of the rotor sleeve leads in particular to a pressure applied to the excitation coils which is at least 1000 MPA, preferably at least 1200 MPA, and / or a maximum of 3000 MPA, preferably a maximum of 1600 MPA.

[0023] The preferred number of poles is between 6 and 16. This number is not practically feasible with the current technology, as it would only be possible with insufficient slot fill factors. By separately preparing the excitation coils and pre-tensioning them, high slot fill factors can be achieved even with high pole counts.

[0024] Preferably, the respective prestress transmission element is designed in the shape of a groove wedge. Alternatively or additionally, the respective prestress transmission element is designed in the shape of a circular segment or arcuate cross-section.

[0025] The invention also relates to an electrical machine, in particular a salient-pole machine. The electrical machine comprises a stator and a rotor driven by the stator, as described above.

[0026] Short description of the drawings

[0027] Embodiments of the invention are described in detail below with reference to the accompanying drawings. In the drawing:

[0028] Figure 1 is a schematic illustration of a salient pole machine according to an embodiment of the invention,

[0029] Figures 2 to 5 are schematic illustrations of various steps in the manufacture of a rotor according to a first embodiment of the invention, Figure 6 is a schematic detailed view of the rotor according to the first

[0030] Embodiment of the invention,

[0031] Figures 7 to 9 each show schematic illustrations of various steps in the manufacture of a rotor according to a second embodiment of the invention, and

[0032] Figure 10 is a schematic illustration of a rotor according to a third embodiment of the invention.

[0033] Embodiments of the invention

[0034] Preferably, all identical components, elements and / or units in all figures are provided with the same reference numerals.

[0035] Figure 1 shows a schematic view of an electrical machine 11 designed as a salient-pole machine. The electrical machine 11 has a stator 12 and a rotor 1 driven by the stator 12.

[0036] The rotor 1 has a rotor body 2 extending around a rotor axis 100 and having a plurality of salient poles 4. The rotor body 2 is, in particular, a rotor core. A rotor slot 5 is formed between adjacent salient poles 4. Each pole shaft 4a of one of the salient poles is enclosed by an excitation coil 6. The rotor 1 has an excitation winding 6a that encompasses all of these excitation coils.

[0037] In addition, a rotor sleeve 7 is provided, which surrounds the rotor body 2 with respect to a circumferential direction 300 around the rotor axis 100. The rotor sleeve 7 preferably has a wall thickness of at least 0.5 mm, preferably at least 0.6 mm, and a maximum of 1.5 mm, preferably 1.4 mm.

[0038] At least one prestress transmission element 8 is provided in the rotor slots 5 and is arranged in the radial direction 200 between the rotor sleeve 7 and the excitation winding 6a. The prestress transmission element 8 is designed to transmit a mechanical prestress of the rotor sleeve 7 to the excitation winding 6a. Various variants of the prestress transmission element 8 are described below. The production of a first variant is illustrated in Figures 2 to 5, each figure showing a different point in time during production.

[0039] Figure 2 shows the rotor body 2 of the rotor 1. The salient poles 4 are designed without pole shoes, which allows the excitation coils 6 to be radially mounted on the pole shafts 4a. As shown in Figure 1, each excitation winding can be pre-wound on a tool 14. This results in a single-tooth winding. By winding outside the rotor slot 5, optimal excitation windings 6a can be prepared and high slot fill levels can be achieved. Figure 3 schematically shows the sliding-on of an excitation coil 6. Figure 4 shows a state in which all salient poles 4 are provided with an excitation coil 6.

[0040] A preload transmission element 8 is provided as a separate insert in each rotor slot 5. The preload transmission elements 8 extend in the axial direction of the rotor slot 5, i.e., along the rotor axis 100. The respective preload transmission element 8 protrudes in the radial direction 200 beyond the salient poles 4 of the respective rotor slot 5.

[0041] As shown in Figure 5, a rotor sleeve 7 is attached. The rotor sleeve 7 exerts a preload force on the preload transmission elements 8, whereby the preload transmission elements 8 transmit the preload to the corresponding areas of the excitation coils 6 in the respective rotor slot 5. Thus, the preload of the excitation winding 6a in the radial direction 200 is achieved.

[0042] The preload transmission elements 8 protrude from the rotor body 2 in the axial direction. In the circumferential direction 300 around the rotor axis 100, the preload transmission elements 8 are surrounded by the rotor sleeve 7. In this way, the preload of the rotor sleeve 7 is evenly applied to the excitation winding 6a by means of the preload transmission elements 8. In particular, the preload is transmitted over the entire axial length of the rotor body 2.

[0043] Figure 6 shows a schematic detailed view of the rotor 1 according to the first exemplary embodiment. It is provided, in particular, that the respective preload transmission element 8 is positively fastened or anchored at its ends in the circumferential direction 300 to the salient poles 4 of the respective rotor slot 5. This is achieved, in particular, by clamping each preload transmission element 8 between the salient poles 4 of the respective rotor slot 5 in the circumferential direction 300.

[0044] Furthermore, an air gap 10 is provided within a rotor slot 5 between two coil sides of two excitation coils 6. This air gap 10 serves, in particular, as an axial cooling channel for dip-impregnated windings to increase continuous power.

[0045] For this purpose, the cooling medium is introduced via a shaft and a flow-connected rotor lamination cut or a rotor-driven balancing disc.

[0046] Figures 7 to 9 schematically show various states during the manufacture of the rotor 1 according to a second variant. In this case, the salient poles 4 have pole shoes, each of which protrudes into the two adjacent rotor slots 5 with two pole collars 9. Figure 7 shows such an illustration.

[0047] The excitation coils 6 are in turn prefabricated as separate components, for example by winding on a tool 14. The pole collars 9 of the pole shoes can each be plastically bent around an axis at the base of the respective pole collar 9. This allows the respective excitation coil 6 to be plugged onto the respective salient pole 4, in particular pole shaft 4a. By bending, it is particularly possible to align the pole collars 9 in the radial direction 200 with the pole shafts 4a. After the excitation coil 6 has been plugged on, the pole collars 9 can be bent back. It is intended that the pole collars 9 of the same rotor slot 5 each form the preload transmission elements 8.

[0048] Figure 8 shows the pole collars 7 in a bent state, with the excitation coils 6 applied to all salient poles 4. The pole collars 9 are then bent back and at least partially enclosed in the circumferential direction 300 by a rotor sleeve 7. This state is shown in Figure 9.

[0049] The pole collars 9 each have at least one weakened portion 9a at their base. This weakened portion, in particular, has a recess or indentation to reduce bending resistance. The respective bias voltage transmission element 8 is designed to be magnetically and / or electrically insulating or partially magnetically conductive.

[0050] Figure 10 shows a schematic illustration of a rotor 1 according to a third variant. In this variant, the salient poles 4 are designed without pole shoes, so that the excitation windings 6 can be applied to the pole shafts 4a, analogously to the first variant. It is provided that the respective bias voltage transmission element 8 has stamped laminations 9b embedded in a matrix, in particular made of plastic. In particular, the bias voltage transmission elements 8 form loose pole collars that interact with the salient poles 4 in a pole-shoe-like manner.

[0051] In all variants, the excitation coils 6 are fully or at least partially impregnated with an impregnating material. The impregnating material is preferably resin. Alternatively or additionally, each rotor slot 5 is preferably potted with a potting material. The potting material is also preferably resin. This improves the stability, aerodynamics, and temperature behavior of the rotor 1.

Claims

Claims 1 . Rotor (1 ) of an electrical machine (10) comprising - a rotor body (2) extending around a rotor axis (100), in particular a rotor core, with a plurality of salient poles (4), wherein a rotor groove (5) is formed between each adjacent salient pole (4), - an excitation winding (6a) comprising a plurality of excitation coils (6), each enclosing a pole shaft (4a) of one of the salient poles (4), and - a rotor sleeve (7) which surrounds the rotor body (2) with respect to a circumferential direction (300) around the rotor axis (100), characterized in that at least one prestress transmission element (8) is provided in at least one of the rotor slots (5), which is arranged in the radial direction (200) between the rotor sleeve (7) and the excitation winding (6a) and is designed to transmit a mechanical prestress of the rotor sleeve (7) to the excitation winding (6a).

2. Rotor (1) according to claim 1, characterized in that the salient poles (4) are designed without pole shoes for radially plugging the excitation coils (6) onto the pole shafts (4a) and the bias voltage transmission element (8) is a separate insert which extends in the axial direction of the rotor slot (5).

3. Rotor (1) according to claim 2, characterized in that the respective preload transmission element (8) protrudes in the axial direction from the rotor body (2) and is enclosed by the rotor sleeve (7).

4. Rotor (1) according to one of claims 2 to 3, characterized in that the respective prestress transmission element (8) extends in the radial direction (200) beyond the salient poles (4) of the respective rotor slot (5).

5. Rotor (1) according to one of claims 2 to 4, characterized in that the respective prestress transmission element (8) is positively fastened or anchored in the circumferential direction (300) at its ends to the salient poles (4) of the respective rotor slot (5), in particular is clamped in the circumferential direction (300) between the salient poles (4) of the respective rotor slot (5).

6. Rotor (1) according to one of claims 2 to 5, characterized in that the respective prestress transmission element (8) has, in particular punched, lamellae (9b) which are embedded in a matrix, in particular made of plastic.

7. Rotor (1) according to claim 1, characterized in that the salient poles (4) have pole shoes, each of which projects with two pole collars (9) into the two adjacent rotor slots (5), wherein the pole collars (9) of the pole shoes are each plastically bendable about an axis at the base of the respective pole collar (9) for plugging the respective excitation coil (6) onto the respective salient pole (4), in particular in order to be oriented in the radial direction (200) in alignment with the pole shafts (4a), wherein the pole collars (9) of the same rotor slot (5) each form the bias voltage transmission elements (8).

8. Rotor (1) according to claim 7, characterized in that the pole collars (9) each have at least one weakening (9a) at their base, in particular a recess or indentation, to reduce the bending resistance.

9. Rotor (1) according to one of the preceding claims, characterized in that the respective bias voltage transmission element (8) is designed to be magnetically and / or electrically insulating or is partially magnetically conductive.

10. Rotor (1) according to one of the preceding claims, characterized in that an air gap (10) remains within a rotor groove (5) between two coil sides of two excitation coils (6), which air gap is designed in particular as a cooling channel.

11. Rotor (1) according to one of the preceding claims, characterized in that each excitation coil (6) is completely or at least partially impregnated with an impregnating material, in particular with resin, and / or each rotor groove (5) is cast with a casting material, in particular with resin.

12. Electrical machine (11), in particular a salient pole machine, comprising a stator (12) and a rotor (1) drivable by the stator (12) according to one of the preceding claims.

Images