WO2021026575A1

WO2021026575A1 - Rotor

Info

Publication number: WO2021026575A1
Application number: PCT/AT2020/060290
Authority: WO
Inventors: Dietmar Andessner; Christian DORFBAUER; Zi Li; Lucas YANG
Original assignee: Miba Sinter Austria Gmbh
Priority date: 2019-08-09
Filing date: 2020-08-07
Publication date: 2021-02-18
Also published as: AT522826A1

Abstract

The invention relates to a rotor (3) for an axial flux machine (1), comprising a metallic rotor core (4) and multiple permanent magnets (5) arranged on the rotor core (4), said rotor core (4) having recesses, such as pockets (8), in which the permanent magnets (5) are arranged.

Description

ROTOR

The invention relates to a rotor for an electrical axial flux machine, comprising a metallic rotor core and a plurality of permanent magnets which are arranged on the rotor core.

The invention further relates to an electrical axial flux machine, comprising a rotor and a stator.

In addition, the invention relates to a method for producing a rotor for an electrical axial flow machine, according to which a metallic rotor core is provided and a plurality of permanent magnets are arranged on the rotor core.

Electric machines with a disc-shaped rotor or electric disc armature machines allow high torques and power densities in short axial Bauräu men. A stator generates an axially aligned magnetic flux which is superimposed on the rotor flux and which runs through permanent magnets of a rotor.

As a result of efforts to reduce greenhouse gases, electrical machines are increasingly becoming the focus of research on drives for vehicles. There are many different designs of such electrical machines. For example, they can have a stator next to a rotor, a rotor between two stators or a stator between two rotors. Usually the rotor has a disk-shaped rotor core on which is equipped with permanent magnets.

The connection between the permanent magnets and the rotor core can also be configured differently. For example, from WO 01/11755 A1 it is known to embed the permanent magnets in a fiber-reinforced or fabric-reinforced plastic and to connect them positively to the surrounding plastic.

DE 10 2015 220 845 A1 describes a rotor in which the permanent magnets are held in the axial direction in axia len openings in the rotor disk via spring elements.

With regard to the increase in the performance of such electrical machines, various designs are also described. For example, DE 102017 127 157 describes it Al a rotor for an axial flux motor with an axis of rotation extending along an axial direction, the rotor extending annularly and having a plurality of permanent magnets along a circumferential direction, the magnetization of which is each oriented in the circumferential direction, the permanent magnets along the Circumferential direction are each arranged spaced from one another, wherein a first material at least comprising a soft magnetic composite is arranged between the permanent magnets.

The present invention is based on the object of making available an improved electrical axial flow machine.

The object of the invention is achieved in the case of the electrical axial flux machine mentioned at the outset in that the rotor core has recesses, for example pockets or grooves, and that the permanent magnets are arranged in the recesses.

The object of the invention is also achieved with the axial flow machine mentioned at the outset, in which the rotor is designed according to the invention.

In addition, the object of the invention is achieved in the aforementioned method in that recesses are generated in the rotor core and the permanent magnets are arranged in the recesses.

The advantage here is that the rotor can be built relatively flat, so that the axial construction length of the axial flow machine can be reduced. In addition, the permanent magnets can be held better in the recesses, so that the forces acting on the permanent magnets, such as centrifugal forces, can be better controlled or the speed of the rotor can be increased. In addition, it can be used to better protect the magnets from mechanical influences.

In order to further increase the performance of the axial flux machine, it can be provided in the rotor according to one embodiment that the recesses with the permanent magnets are arranged on both sides of the rotor core.

In the preferred embodiment variant, the rotor core consists of a rolled electrical sheet or is produced by rolling up an electrical sheet. Due to different magnetic inductances in and across the magnetic direction, the use of the reluctance term in the field weakening range can be achieved. This is advantageous, for example, for the use of the electrical axial flux machine provided with the rotor in a traction machine. In addition, eddy current losses in the rotor yoke can also be reduced. The permanent magnets of the rotor are preferably magnetized in the axial direction of the rotor.

Preferably, according to one embodiment of the invention, the individual layers of the rotor core arranged one above the other in ra dialer direction are connected to one another from the spirally ge rolled electrical sheet in order to give the recesses a higher stability.

According to a further embodiment of the invention, it can be provided that the permanent magnets are arranged within the rotor core. Although the formation of the recesses can thus be more difficult, this embodiment variant has the advantage that the aforementioned effects can be further improved.

According to a preferred embodiment, the recesses in the rotor core for accommodating the permanent magnets are already produced when rolling up, which can simplify their production, since the rolled up rotor core no longer has to be machined after rolling to form the pockets.

According to a preferred embodiment of the method, it can be provided that the recesses in the rotor core are produced by punching the electrical steel sheet on one or both sides. It can also be used to shorten the process time for manufacturing the rotor core.

For better fixation of the permanent magnets in the recesses, it can be provided according to a further variant embodiment of the method that the permanent magnets are covered on the outside in the radial direction with an, in particular metallic, cover.

According to a variant embodiment of the invention, the cover can be made from the electrical sheet, so that the cover can be produced simply when the electrical sheet is rolled up to form the rotor core. According to a further embodiment variant, it can also be provided that the cover is made from a stainless steel strip, the stainless steel strip also being able to be connected to the electrical steel sheet according to an embodiment variant of the method. The stainless steel strip has a higher tensile strength than normal electrical steel. In addition, it can be advantageous to use a stainless steel which is not or hardly magnetically conductive.

According to another variant of the invention, the cover can also be produced by pressing a ring onto the rotor core, which simplifies the introduction of the permanent magnets, since the ring can be pressed on in a separate production station. The ring can be made from metal or from fiber composite materials. It can be made available with lower weight design variants. These have a lower mass moment of inertia and can therefore have better dynamics.

For a better understanding of the invention, it is explained in more detail with reference to the following figures.

They each show in a simplified, schematic representation:

1 shows a variant embodiment of an electrical axial flow machine;

2 shows a first variant embodiment of a rotor for an electrical axial flow machine in an oblique view;

3 shows a detail of the first embodiment variant of the rotor in a view of its end face;

4 shows a further variant embodiment of a rotor for an electrical axial flow machine in an oblique view;

Fig. 5 shows another embodiment of a rotor for an electrical Axialflussma machine in an oblique view.

As an introduction, it should be noted that in the differently described embodiments, the same parts are provided with the same reference numerals or the same component names. where the disclosures contained in the entire description can be applied analogously to the same parts with the same reference numerals or the same component names. The position details chosen in the description, such as above, below, side, etc., refer to the figure immediately described and shown and these position details are to be transferred accordingly to the new position in the event of a change in position.

1 shows schematic design variants of an electrical axial flux machine 1, including a stator 2 and a rotor 3. The axial flux machine 1 can, for example, also have two stators 2, between which the rotor 3 is arranged, as shown by the second stator 2 shown in dashed lines in FIG Fig. 1 is shown. However, a variant of the electrical axial flow machine 1 with only one stator 2, which is arranged between two rotors 3, is also possible. In the event that the electrical axial flow machine 1 has a plurality of rotors 3, all rotors 3 are preferably designed in the same way, so that the following explanations can be applied to all rotors 3.

Since this basic structure of electrical axial flux machine 1 is known per se, reference is made to the relevant prior art for further details, in particular the design of the at least one stator 2.

In all variants of the invention, the rotor 3 has a rotor core 4 on which a plurality of permanent magnets 5 are arranged and attached to the rotor core 3, as can also be seen from FIGS. 2 and 3, which show a first variant of the rotor 3 .

The rotor core 4 can have the shape of an at least approximately annular disk. In addition, the rotor core 4 can be arranged on a shaft, for example directly or on a hub 7 of the shaft 6.

The rotor core 4 has pockets 8. In particular, a pocket 8 is provided in the rotor core 4 for each permanent magnet 5, so that a permanent magnet 5 is accommodated in a pocket 8. In general, 5 recesses can be arranged for receiving the permanent magnets, so for example grooves. Therefore, if in the following only pockets 8 Be are taken, then these explanations can also generally be transferred to recesses for receiving the permanent magnets 5 and these recesses should therefore also be read. In the variant of the rotor 3 according to FIGS. 2 and 3, the pockets 8 are arranged within the rotor 3 and are designed to be open in a lateral surface 9 of the rotor core 4. The permanent magnets 5 can thus be pushed radially into the pockets 8.

Web 10 made of the material of the rotor core 4 are formed between the pockets 8. Furthermore, the permanent magnets 5 are also covered by the material of the rotor core 4 on both axial end faces 11 due to the pocket formation mentioned.

The pockets 8 can extend in the radial direction over an entire radial height 12 of the rotor core 4, or only over a partial area of this radial height 12, in which case the pockets 8 can also be designed like a blind hole.

In a circumferential direction 13, 8 recesses 16, 17 can be arranged on both sides between the permanent magnets 5 and Be tenwwall 14, 15 of the pockets. These recesses 16, 17 are formed in particular by the spaced arrangement of the permanent magnets 5 to the side walls 14, 15 of the pockets 8. Furthermore, the recesses 16, 17 can extend over the entire radial height 12 or only a partial area of this radial height 12 of the rotor core 4.

The recesses 16, 17 can, for example, have a T-shaped cross section, as can be seen from FIGS. 2 and 3.

The recesses 16, 17 taper the rotor core 4 and a thin, soft magnetic web 10 is formed, which can be more easily saturated by the permanent magnets 5. A reduction in the loss of the magnetic effect due to this "short circuit" in the magnetic circuit can thus be achieved.

In principle, the rotor core 4 can be made from a solid material or consist of it. In the preferred embodiment of the rotor 3 or the axial flux machine 1, however, the rotor core 4 consists of a laminated core made of electrical sheet 18. For this purpose, electrical sheet metal rings can be used which are arranged one above the other in the radial direction to form the laminated core. In terms of process technology, however, it is simpler if a sheet metal strip is wound spirally from the electrical sheet 18, that is, the rotor core 4 consists of a rolled, band-shaped electrical sheet 18, as can be seen in particular in FIG. The laminated core thus has several layers 19 made of electrical steel 18. The axial width of the Layers 19 corresponds to the axial width of the strip-shaped electrical steel sheet 18. The electrical steel sheet 18 is therefore not further divided in the axial direction after being rolled up to form the laminated core.

The layers 19 of the laminated core are preferably connected to one another, in particular by means of radial connection techniques on the disgusted electrical steel. For example, the layers 19 can be welded to one another by one or both sides on the axial end face (s) of the rotor core 4, for example connected by means of laser welding. The weld seam is preferably formed linearly and leading in the radial direction. A plurality of weld seams can also be formed per axial face of the rotor core 4. The weld can also be made point-like.

The laminated core can also have layers 19 connected by punching, caulking or generally by clamping. The die-stacking per se is known from the prior art, so that further explanations are unnecessary.

The layers 19 can also be connected to one another by spokes.

Furthermore, the layers 19 can be rolled under tension to form the laminated core, so that an (additional) frictional connection can exist between the layers 19.

The layers 19 can also be glued together.

Of course, other suitable connection techniques for connecting the layers 19 can also be used.

The rotor core 4 can also be connected to the hub 7.

The electrical sheet 18 can be an electrical sheet 18 corresponding to the prior art for this purpose. Sheet metal grades with high mechanical strengths are preferred, especially for higher speeds.

The layers 19 of the laminated core are arranged running perpendicular to the end faces 11 of the permanent magnets 5.

As can be seen from FIGS. 2 and 3, the pockets 8 are preferably designed such that the rotor core 4 rests directly on the permanent magnets 5 on both sides. In the axial flux machine 1 (FIG. 1), the permanent magnets 5 preferably have a magnetization in the axial direction, ie in the direction of the axis of rotation of the shaft 6.

As stated above, it is possible with the rotor 3 to provide an additional reluctance term in the field weakening range. This is achieved by the inductance difference in (d) and across (q) to the direction of the magnet. This is indicated by the two arrows 20, 21 in FIG. 3.

4 and 5 further and possibly independent embodiments of the rotor 3 are shown, again with the same reference numerals or component names as in the preceding FIGS. 1 to 3 are used for the same parts. In order to avoid unnecessary repetitions, reference is made to the detailed description of the previous FIGS. 1 to 3.

In contrast to the variant of the rotor 3 according to FIGS. 2 and 3, the pockets 8 (e.g. FIG. 3) in the variant of the rotor 3 according to FIG. 4 are also covered on the radially outer lateral surface 9 (FIG. 2). For this purpose, a cover 22 can be arranged on this jacket surface 9, which covers the openings of the pockets 8. The cover 22 is preferably made of a metallic material. However, it can also consist of another suitable material, for example a plastic such as a thermoplastic or a thermosetting plastic.

According to one embodiment of the invention, it can be provided that the cover 22 is produced from the electrical sheet 18 itself. For this purpose, the electrical sheet 18 can be further wound after the insertion of the permanent magnets 5 in the pockets 8 of the rotor core 4 until the pockets 8 are also covered on the radially outer circumference. For this purpose, one or more additional layers 19 of the strip-shaped electrical steel sheet 18 can be disgusted.

For the sake of completeness, it should be mentioned at this point that the terms “wound” and “rolled” are used synonymously with regard to a sheet metal package produced from a strip-shaped electrical sheet 18.

Instead of the electrical steel sheet 18, according to a further embodiment variant, a stainless steel band can be used that is wound around the radially outer jacket surface of the rotor core 4 becomes. The stainless steel strip can optionally be connected to the strip-shaped electrical sheet 18, for example welded, so that the cover 22 in this embodiment variant with the different materials for the laminated core and the cover 22 also in the context of rolling up the electrical sheet 18 to the rotor core 4 by further winding can be produced.

According to a further embodiment variant of the rotor 3, it can be provided that the cover 22 is made from a ring which is pressed onto the rotor core 4.

5 shows a variant of the rotor 3 in which the pockets 8 are not arranged or formed within the rotor core 4, but rather as depressions in at least one, preferably in both, axial end faces 23, 24 of the rotor core 4 the permanent magnets 5 are arranged on one or both sides of the rotor core 4, only the double-sided variant being shown in FIG.

In the circumferential direction 13, the permanent magnets 5 are again separated from one another by the radially extending webs 10. In the embodiment variant with the arrangement of the permanent magnets 5 on both sides, webs 24 are additionally formed in the axial direction.

In contrast to the preceding variant embodiment of the rotor 3 according to FIGS. 2 and 3, the permanent magnets 5 also bear (directly) on the side walls 14, 15 of the pockets 8.

Furthermore, the permanent magnets 5 preferably extend over the entire radial height 12 of the rotor core 4. In this embodiment variant, the rotor core 4 also preferably consists of the electrical sheet 18, as is indicated in FIG. 5 with the aid of a web 10.

In all embodiment variants of the rotor 3, the permanent magnets 5, viewed in the direction of the axial direction, preferably have an at least approximately circular segment-shaped shape. But they can also have a different shape, for example trapezoidal.

The pockets 8 in the rotor core 4 can be formed after the rotor core 4 has been manufactured. In the preferred embodiment of the invention, however, the pockets 8 are already formed during the manufacture of the rotor core 4. In particular, this takes place when the electrical steel sheet 18 is rolled up to form the rotor core 4, in that on which the pockets 8 are to be formed, openings are produced which then lie one above the other in the radial direction after the electrical steel strip has been wound up and form the pockets 8. The openings are particularly preferably produced by punching.

After the circumferential lengths of the layers 19 of the electrical steel sheet 18 in the rotor core increase from the inside to the outside and the pockets also preferably widen from the inside to the outside (as viewed in the direction of the axial direction), the cutouts in the strip-shaped electrical steel sheet 18 are preferably at a variable distance from one another and variable width.

The exemplary embodiments show and describe possible design variants of the invention, it being noted at this point that combinations of the individual design variants are also possible with one another.

For the sake of order, it should finally be pointed out that, for a better understanding of the structure, the electrical axial flux machine 1 and the rotor 3 are not necessarily shown to scale.

List of reference symbols axial flux machine stator rotor rotor core permanent magnet shaft hub pocket lateral surface web end face height circumferential direction side wall side wall recess recess electrical sheet position arrow arrow cover end face

Claims

Patent claims

1. Rotor (3) for an axial flux machine (1), comprising a metallic rotor core (4) and several permanent magnets (5) which are arranged on the rotor core (4), characterized in that the rotor core (4) has recesses, such as pockets (8), and that the permanent magnets (5) are arranged in the recesses.

2. Rotor (3) according to claim 1, characterized in that the recesses with the permanent magnets (5) are arranged on both sides of the rotor core (4).

3. rotor (3) according to claim 1 or 2, characterized in that the rotor core (4) consists of a rolled electrical sheet (18).

4. rotor (3) according to claim 3, characterized in that the individual layers (19) of the rotor core (4) from the rolled electrical sheet (18) are additionally connected to one another.

5. rotor (3) according to one of claims 1 to 3, characterized in that the permanent magnets (5) are arranged within the rotor core (4).

6. Electric axial flux machine (1), comprising a rotor (3) and a stator (2), characterized in that the rotor (3) is formed according to one of claims 1 to 5.

7. Electric axial flux machine (1) according to claim 6, characterized in that the permanent magnets of the rotor (3) are magnetized in the axial direction of the rotor (3).

8. A method for producing a rotor (3) for an electrical Axialflussma machine (1), according to which a metallic rotor core (4) is provided and a plurality of permanent magnets (5) are arranged on the rotor core (4), characterized in that in Rotor core (4) recesses, such as pockets (8), are generated and the permanent magnets (5) are arranged in the recesses.

9. The method according to claim 8, characterized in that the rotor core (4) is made from an electrical sheet (18) by rolling up the electrical sheet (18).

10. The method according to claim 9, characterized in that the recesses in the rotor core (4) are produced when the electrical sheet (18) is rolled up.

11. The method according to claim 9 or 10, characterized in that the recesses in the rotor core (4) are produced by punching the electrical sheet (18) on one or both sides.

12. The method according to any one of claims 9 to 11, characterized in that by rolling up the electrical steel sheet (18), a spiral-shaped laminated core with several layers (19) lying one above the other in the radial direction is produced from the sheet metal, the individual layers (19) are also connected to each other.

13. The method according to any one of claims 8 to 12, characterized in that the permanent magnets (5) are arranged within the rotor core (4).

14. The method according to any one of claims 8 to 13, characterized in that the permanent magnets (5) are covered in the radial direction on the outside with an, in particular metallic, cover (22) from.

15. The method according to claim 14, characterized in that the cover (22) is made from the electrical sheet (18).

16. The method according to claim 14, characterized in that the cover (22) is made from a stainless steel strip.

17. The method according to claim 16, characterized in that the stainless steel strip is connected to the electrical sheet (18).

18. The method according to claim 14, characterized in that the cover (22) is produced by pressing a ring onto the rotor core (4).