DE102022004795B4 - Rotor for an electrical machine, in particular an axial flux machine, and a corresponding electrical machine - Google Patents

Abstract

The invention relates to a rotor (1) for an electrical machine (3), wherein the rotor (1) is rotatable in relation to a rotor axis (2), with a disk-shaped rotor base body (5), and a disk-shaped rotor core (6) which is arranged on the rotor base body (5), wherein - a radial outer region (11) of the rotor core (6) is delimited by a radial outer region (12) of the rotor base body (5), - a radial inner region (13) of the rotor core (6) is delimited by a radial inner region (14) of the rotor base body (5), and - the radial inner region (13) of the rotor core (6) and the radial inner region (14) of the rotor base body (5) are arranged at a distance from one another. In this case, an axial stiffness of the rotor core (6) at the radial inner region (13) of the rotor core (6) is compared to an axial stiffness of the radial outer region (11) of the rotor core (6) and/or an axial rigidity of a radial central region of the rotor core (6). According to the invention, the axial rigidity of the rotor core (6) at the radial inner region (13) of the rotor core (6) is reduced by a recess (22), in particular in the form of a circumferential groove. Furthermore, the invention relates to an electrical machine (3).

Description

The invention relates to a rotor for an electrical machine, wherein the rotor is rotatable in relation to a rotor axis. The rotor has a disk-shaped rotor base body and a disk-shaped rotor core, which is arranged on the rotor base body. A radial outer region of the rotor core is delimited by a radial outer region of the rotor base body and a radial inner region of the rotor core is delimited by a radial inner region of the rotor base body.

Furthermore, the invention relates to an electrical machine with a stator and at least one rotor.

In axial flow machines as electrical machines, the rotors have large diameters due to their design. Therefore, their edge areas reach very high circumferential speeds at high speeds, which result in high centrifugal forces. Although the rotors consist of different components, they are designed as solid disks in order to have low-drag, acoustically inconspicuous aerodynamics.

For example, the EP 3 687 047 A1 , the WO 2016 / 113 567 A1 and the US 2015 / 0 244 219 A1 Axial flow machines with a disk-shaped rotor.

From the genre-defining text JP 2009 - 131 087 A A rotor of an electrical machine is known whose strength is improved in the direction of its axis of rotation. The spiral-wound rotor core and the magnets are arranged in a concave space in the outer area of the rotor base body, and are fixed and held in place by a connecting element due to the special shape of the space.

The JP 2006 - 304 474 A describes an electric motor with an axial air gap that achieves high torque and high performance using a reluctance torque. For this purpose, magnets are arranged in receiving areas of the rotor base body, which in some embodiments are covered by a rotor core as a yoke. Depending on the design, the yoke can have different shapes and also contribute different strengths to the rotor.

The document JP 2021 - 2 914 A discloses an electrical machine with an axial air gap, wherein the rotor consists of a rotor base body in whose circumferential groove magnets are arranged, which are fixed with resin. The groove has recesses through which the resin can hold the magnets securely in the groove in a form-fitting manner.

In addition, the CN 214 124 956 U also an electric motor with an axial permanent magnet hub, where the permanent magnets are inserted and held in receptacles of a steel frame on a sheet-metal rotor core.

One disadvantage of the axial flux machines in the state of the art is that the rotor of an axial flux machine is a material connection between the rotor yoke and the rotor base body, in particular between the magnet and the magnet carrier to the rotor yoke, and represents an area of high stress concentration in the inner radius. The reason for this is the deformation of the adjacent areas under the influence of centrifugal force. Excessive centrifugal forces destroy the rotor assembly and therefore limit the maximum permissible speed. An electric machine with a low maximum speed has only low performance.

Therefore, an object of the present invention is to provide a rotor, in particular for an axial flow machine, which can be operated in a higher speed range than in the prior art.

This object is achieved by a rotor and an electrical machine according to the independent patent claims. Useful further developments arise from the dependent patent claims.

One aspect of the invention relates to a rotor for an electrical machine, wherein the rotor is rotatable with respect to a rotor axis, with a disk-shaped rotor base body, a disk-shaped rotor core which is arranged on the rotor base body, wherein a radial outer region of the rotor core is delimited by a radial outer region of the rotor base body, a radial inner region of the rotor core is delimited by a radial inner region of the rotor base body, wherein the radial inner region of the rotor core and the radial inner region of the rotor base body are arranged at a distance from one another.

According to the invention, the axial rigidity of the rotor core at the radial inner region of the rotor core is reduced compared to the axial rigidity of the radial outer region of the rotor core and/or the axial rigidity of a radial central region of the rotor core. As a result, lower release forces act on the contact surface between the inner region of the rotor core and the rotor base body.

According to the invention, the axial stiffness of the rotor core is reduced in the radial inner region of the rotor core by a recess formed there, such as a groove. This allows a reduction in the axial stiffness to be achieved in a particularly simple manner.

The rotor according to the invention can be used efficiently in electrical machines with high speed ranges. The rotor can therefore be used for powerful electrical machines. The use of the proposed rotor in axial flow machines is particularly advantageous, since the proposed rotor can be used to create or provide axial flow machines capable of high speeds.

Furthermore, the proposed rotor offers the advantage that different deformations caused by centrifugal force in adjacent areas of the rotor components of the rotor, such as the rotor yoke and rotor base body, do not lead to disintegration of the entire assembly, i.e. the rotor. The rotor according to the invention can therefore be used in axial flow machines, so that such an axial flow machine has a higher speed limit range or a higher speed limit compared to the prior art.

A further aspect of the invention relates to an electrical machine, in particular an axial flux machine, with a stator and a rotor according to the previous aspect or an advantageous development thereof, wherein the rotor is rotatable about a rotor axis in relation to the stator.

In particular, the rotor of the previous aspect described above can be used and in particular employed in the electrical machine just described.

In particular, the electrical machine is an axial flux machine. For example, the electrical machine can have the aforementioned rotor according to the invention. In particular, the electrical machine has a stator and a rotor according to the invention on each side of the stator.

Thus, the electric machine can be designed as an axial flux electric motor or an axial flux machine with double rotor topology.

Further advantages, features and details of the invention emerge from the following description of preferred embodiments and from the drawing(s). The features and combinations of features mentioned above in the description as well as the features and combinations of features mentioned below in the description of the figures and/or shown alone in the figures 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 invention.

• 1 eine schematische Ansicht eines erfindungsgemäßen Rotors;
• 2 eine schematische Darstellung eines Rotorkerns des Rotors aus 1;
• 3 eine beispielhafte, seitliche Schnittansicht des Rotors aus 1;
• 4 einen beispielhaften Ausschnitt eines Bereichs der Schnittansicht aus 3; und
• 5 eine schematische Darstellung einer elektrischen Maschine mit zumindest einem Rotor aus 1.

The following figures show:

• 1 a schematic view of a rotor according to the invention;
• 2 a schematic representation of a rotor core of the rotor from 1 ;
• 3 an exemplary side sectional view of the rotor from 1 ;
• 4 an exemplary section of a section view from 3 ; and
• 5 a schematic representation of an electrical machine with at least one rotor made of 1 .

In the figures, functionally identical elements are provided with the same reference symbols.

In the 1 a schematic representation of a rotor 1 is shown. In particular, a side view, i.e. a top view in relation to a rotor axis 2 or rotation axis (cf. for example 2 ). The rotor 1 is rotatable in relation to the rotor axis 2. The rotor axis 2 can also be the rotation axis of an electrical machine 3 (cf. 4 ). In particular, rotor axis 2 corresponds to the x-axis.

The electrical machine 3 can be, for example, an axial flux machine. The electrical machine 3 can have a stator 4. The stator 4 can be arranged adjacent to a rotor 1 on each of its two axial sides.

The rotor 1 has a disk-shaped rotor base body 5 or a rotor carrier. Furthermore, the rotor 1 can have a disk-shaped rotor core 6 or rotor yoke (cf. 2 ). The disk-shaped rotor core 6 can be arranged on, in particular on, the rotor base body 5. In other words, viewed axially, the rotor core 5 can rest on the rotor base body 5.

The rotor 1 can have a plurality of magnets 7, which can be designed, for example, as permanent magnets or permanent magnets, which can be arranged at a distance in a circle on the rotor core 6. The plurality of magnets 7 can be directly connected to the rotor core 6. Otherwise, the plurality of magnets 7 be fixed to the rotor core 6 by means of a magnet carrier 8. In particular, the magnets 7 can be enclosed with the aid of the magnet carrier 8 and thus held on the rotor core 6. For example, the disk-shaped rotor base body 5 can have a central rotor base body opening 9 or a through-opening. The rotor base body opening 9 serves in particular to accommodate a shaft, hub and/or a rotatable element for power transmission.

In the 2 1 shows a schematic representation of the rotor core 6. As can be seen, this is disk-shaped. The disk-shaped rotor core 6 can also have a central rotor core opening 10, wherein a diameter of the rotor core opening 10 can be equal to or substantially equal to a diameter of the rotor base body opening 9. In particular, the rotor core 6 has a recess 22 or cavity 15 on the inner circumference, for example in the form of a groove.

In the 3 is an exemplary sectional view of the rotor 1 from the 1 shown.

According to the invention, a radial outer region 11 of the rotor core 6 is delimited by a radial outer region 12 of the rotor base body 5. In other words, the radial outer region 11 of the rotor core 6 is impaired with regard to a radial outward expansion by the radial outer region 12 of the rotor base body 5. The radial outer region 12 of the rotor base body 5 thus delimits or frames the radial outer region 11 of the rotor core 6. The radial outer region 12, like a radial central region of the rotor base body 5, is designed as a solid body. Furthermore, a radial inner region 13 of the rotor core 6 is delimited by a radial inner region 14 of the rotor base body 5. In other words, the rotor core 6 is delimited or bordered by the rotor base body 5 on its radial end sides. In other words, the rotor core 6 can be enclosed or framed by the rotor base body 5.

In order to be able to counteract the loads on the components of the rotor 1, the radial inner region 13 of the rotor core 6 and the radial inner region 14 of the rotor base body 5 are arranged at a distance from one another. The radial inner regions of the rotor core 6 and the rotor base body 5 therefore do not touch on their radial inner sides. It is particularly advantageous if a cavity 15 is formed between the radial inner region 13 and the radial inner region 14. This cavity 15 can be annular, for example. The axial rigidity of the radial inner region 13 is reduced by a recess 22 formed here in the form of a circumferential groove.

In particular, the rotor 1 consists of the components rotor base body 5, optionally the magnet carrier 8 and the magnets 7. The rotor core 6 can have a reduced rigidity in the area of its inner radius due to the recess 22. This can be achieved by the cavity 15.

For example, the radial inner region 13 may have a side wall 16 (see 4 ) of the rotor core opening 10. The radial inner region 14 can, for example, be a side wall 17 (see 4 ) of the rotor body opening 9. The side wall 16 of the rotor core opening 10 and an outer side 18 (compare 4 ) of the radial inner region 14 can have a predetermined radial distance 19 from each other (cf. 4 ).

Accordingly, the rotor core 6 has a distance 19 in the area of its inner radius, so that in this area the rotor core 6 is not connected or attached to the rotor base body 5. This ensures that the centrifugal forces which the components introduce into the rotor base body 5 on the outside do not lead to an impermissible deformation of the rotor core 6 at its inner radius. Instead, the centrifugal forces are guided here, bypassing the rotor core 6 in the rotor base body 5, through a hub 20 to the opposite side (a side facing away from the stator 4) of the rotor 1. They therefore support each other indirectly without leading to an increase in stress in the connection between the rotor core 6 and the rotor base body 5. Furthermore, in addition to or instead of this, the cavity 15 can be partially, in particular completely, filled with a casting compound.

Thus, a high-speed axial flow machine can be created with the help of the rotor 1. The components of the rotor 1 are partially not connected or not rigidly connected to the hub 20 of the rotor base body 5 in their inner areas. Here they have an area of reduced rigidity, such as the cavity 15.

In a further embodiment, the rotor core 6 may not be completely fixed to the inside of the rotor carrier or rotor base body 5. This area can be left open in order not to place unnecessary strain on the structural integrity, especially at high speeds. Furthermore, the rotor base body 5 can be designed to be flexible in the radial inner area, i.e. radially inside the rotor core 6, in order to further reduce the strain. This inner area contributes to the fastening enance of the rotor core 6 only to a limited extent and is therefore left free, since otherwise unnecessary loads may occur between the rotor base body 5 and the rotor core 6, which may weaken the structure of the rotor 1.

In one embodiment, it can further be provided that the cavity 15 can be filled with an elastic or at least less rigid material and connected thereto.

For example, the magnets 7 can be integrated or fixed directly in the rotor core 6 or rotor yoke. Optionally, the magnet carrier 8 can be provided for fastening the magnets 7.

The magnet carrier 8, if provided, can be, as shown in the 3 or in the 4 can be seen, cover or cover the cavity 15 at least partially or completely when viewed from the outside. However, this is only one possible example. The magnet carrier 8 can also be arranged in such a way that in particular the area of the distance 19 is not covered by the magnet carrier 8 when viewed from the outside.

In particular, the magnet carrier 8 does not have its own connection in the inner area to the rotor base body 5.

Optionally, the rotor base body 5 can also be specially designed in this radial area, i.e. in the area of the cavity 15, in order to be able to further absorb or reduce the stresses that arise. These can be suitable material treatment measures, such as targeted structural weakening or structural reinforcements or different materials or material mixes, which specifically stiffen the area or reduce its stiffness in order to reduce the structural load on the rotor base body 5, depending on the type of load.

List of reference symbols

1

rotor

2

Rotor axis

3

electric machine

4

stator

5

Rotor base body

6

Rotor core

7

several magnets

8

Magnetic carrier

9

Rotor body opening

10

Rotor core opening

11

radial outer area of the rotor core

12

radial outer area of the rotor body

13

radial inner area of the rotor core

14

radial inner area of the rotor body

15

cavity

16

Side wall of the rotor core opening

17

Side wall of the rotor body opening

18

Outside of the radial inner area of the rotor body

19

Distance

20

hub

22

Recess

Claims (6)

Rotor (1) for an electrical machine (3), wherein the rotor (1) is rotatable in relation to a rotor axis (2), with a disk-shaped rotor base body (5), and a disk-shaped rotor core (6) which is arranged on the rotor base body (5), wherein - a radial outer region (11) of the rotor core (6) is delimited by a radial outer region (12) of the rotor base body (5), - a radial inner region (13) of the rotor core (6) is delimited by a radial inner region (14) of the rotor base body (5), and - the radial inner region (13) of the rotor core (6) and the radial inner region (14) of the rotor base body (5) are arranged at a distance from one another, wherein an axial stiffness of the rotor core (6) at the radial inner region (13) of the rotor core (6) is compared to an axial stiffness of the radial outer region (11) of the rotor core (6) and/or an axial stiffness a radial central region of the rotor core (6); characterized in that the axial rigidity of the rotor core (6) is reduced at the radial inner region (13) of the rotor core (6) by a recess (22), in particular in the form of a circumferential groove. Rotor (1) after Claim 1 , characterized in that a cavity (15) is formed between the radial inner region (13) of the rotor core (6) and the radial inner region (14) of the rotor base body (5), in particular the cavity (15) is at least partially filled with a casting compound. Rotor (1) after Claim 1 or 2 , characterized in that - the disk-shaped rotor core (6) has a central rotor core opening (10), wherein the radial inner region (13) of the rotor core (6) forms a side wall (16) of the rotor core opening (10), and - the disk-shaped rotor base body (5) has a central rotor base body opening (9), wherein the radial inner region (14) of the rotor base body (5) forms a side wall (17) of the rotor base body opening (9). Rotor (1) after Claim 3 , characterized in that the side wall (16) of the rotor core opening (10) and an outer side (18) of the radial inner region (14) of the rotor base body (5) have a predetermined radial distance (19) from one another. Rotor (1) according to one of the preceding claims, characterized by a plurality of magnets (7) which are arranged at a distance from one another in a circle on the rotor core (6), and the plurality of magnets (7) are directly connected to the rotor core (6) or the plurality of magnets (7) are fixed to the rotor core (6) by means of a magnet carrier (8). Electrical machine (3), with - a stator (4), and - at least one rotor (1) according to one of the preceding claims, wherein - the rotor (1) is rotatable about the rotor axis (2) with respect to the stator (4).

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