Rotor for electric machine with magnets having protrusions

Abstract

The invention relates to a rotor (1) for an electric machine (18), comprising a rotor laminated core (2), which comprises a plurality of rotor laminations (3) stacked in the axial direction, which rotor laminations have a plurality of recesses distributed in the circumferential direction, which recesses form magnet pockets (6, 7, 8), and in each pocket a magnet (9, 13, 15) is inserted, the magnets (9, 13, 15) having at least two projections (11, 14, 16) on the outer side (10). The invention also relates to an electric machine (18) having such a rotor (1), and to a vehicle (17) having an electric machine (18).

Description

Field of the Invention

[0001] The present invention relates to a rotor for an electric machine, the rotor having a rotor lamination core which comprises a plurality of rotor laminations stacked in the axial direction and having a plurality of magnet pockets which are arranged distributed in the circumferential direction and form recesses into which magnets are inserted. The axial direction extends parallel to the axis of rotation of the rotor. Background of the Invention

[0002] Electric machines having rotors of this type are increasingly being used in electric drive vehicles or hybrid vehicles. Here, the electric machine is mainly used as an electric motor for driving the wheels or axles of the vehicle. The electric motor can in particular be configured as a synchronous motor or an asynchronous motor.

[0003] The electric motor is usually mechanically coupled to a gearbox for speed adaptation. The electric motor is additionally usually electrically connected to an inverter which generates an AC voltage, in particular a polyphase AC voltage, from the DC voltage supplied from a battery for the operation of the electric motor.

[0004] The stator of the electric machine has a stator lamination core and a stator winding. When a current is applied to the stator winding, an electric rotating field is generated, which causes the rotor to rotate.

[0005] The rotor lamination core consists of a plurality of axially stacked or aligned rotor laminations. Some of the rotor plates have recesses therein which form magnet pockets for the magnets. After the magnets have been inserted into the magnet pockets, a liquid potting compound is usually introduced into the rotor lamination core, which potting compound cures when heated. It must be ensured that the rotor lamination core composed of the stacked rotor laminations is sealed in order to prevent leakage of the potting compound. The tolerances of the magnet pockets and the magnets are selected such that the magnets can be inserted into the magnet pockets without jamming or clogging.

[0006] The aim is to ensure that the magnets are positioned as radially far as possible from the magnet pockets, since the electromagnetic forces are then at a maximum. However, with regard to the tolerances required for mounting the magnets, the magnets can be in a radially inner position or the position is not defined. Therefore, a rotor is needed in which the magnets in the magnet pockets are positioned radially outwards. This radial direction is perpendicular to the axis of rotation of the rotor. Summary of the Invention

[0007] The present invention is therefore based on the object of specifying a rotor in which the magnets in the magnet pockets are positioned radially outwards.

[0008] This object is achieved by a rotor having the features of claim 1.

[0009] In the rotor according to the invention, the magnet has at least two protrusions on its outer side. The outer side can be one of the longer outer sides of the magnet. The dimensions of the protrusions and the dimensions of the magnet match the dimensions of the recess or the magnet pocket that holds the magnet, such that the magnet can be positioned in the magnet pocket without play. In particular, the magnet contacts the inner side of the recess by means of two protrusions on its outer side, such that its position is fixed. This has the advantage that the complex potting with potting compound can be omitted. Accordingly, the rotor according to the invention is characterized by a shorter production time compared to the prior art.

[0010] In the context of the present invention, it is preferred that at least two protrusions point radially inwards or radially outwards. The magnet is inserted into the recess, where the protrusions face the axis of rotation of the rotor. This ensures that the magnet is as far outwards as possible in the radial direction. However, the two protrusions can also point radially outwards.

[0011] In the present application, it is preferred that the magnet has two or more protrusions on its outer side. However, in principle, it is also possible to provide only one such protrusion. In order to prevent the magnet from tilting, it is also possible for the protrusions to extend over a larger area of the outer side of the magnet.

[0012] On the other hand, the magnet can also have more than two such protrusions, for example three, four, five, six, seven, eight, nine, ten, eleven or twelve protrusions located on the same outer side of the magnet.

[0013] An improvement of the invention provides that at least two protrusions are designed such that the outer side of the magnet that is positioned opposite the protrusions is flush with the inner side of the magnet pocket. This improves the retention of the magnet in the magnet pocket such that the magnet does not slide. In particular, the magnet can thus reliably hold the radially outermost position in the magnet pocket.

[0014] It can also be provided that the two protrusions arranged on the outer side of the magnet are at a distance from the edge of the magnet. In particular, the two protrusions can be offset from the edge towards the center of the outer side. However, alternatively, the protrusions can be placed directly on the edge of the magnet. In particular, the protrusions can each be adjacent to or in contact with the edge of the magnet.

[0015] It is also within the scope of the present invention for the protrusions to have a semi-circular or triangular or rectangular cross-section. With regard to their three-dimensional shape, the protrusions can be formed as hemispheres, triangular pyramids, tetrahedral pyramids or cuboids.

[0016] It is particularly preferred that the shape and dimensions of the protrusions are selected such that the magnet is held frictionally in the magnet pocket. The friction between the magnet and the inner side of the magnet pocket holds the magnet firmly in the desired position.

[0017] The rotor according to the invention can be designed such that the rotor lamination core is divided into a plurality of lamination core segments in the axial direction, wherein two adjacent lamination core segments are rotated relative to each other in the circumferential direction. The rotation is typically a few degrees. This measure counteracts the generation of the detent torque.

[0018] In the rotor according to the invention, the protrusions can preferably extend over the entire axial length of the magnet or over a part of the axial length of the magnet. The axial length of the magnet refers to the length of the magnet held in the magnet pocket along the rotation axis of the rotor.

[0019] The protrusions can preferably be arranged at the corners of the magnet respectively. It should be noted that the protrusions do not collide with the contour of the magnet pocket, so that the magnet can be easily inserted into the magnet pocket. The corners and radii of the magnet and the magnet pocket can be designed or dimensioned in a suitable manner for this purpose.

[0020] A plurality of magnets are preferably arranged continuously in the axial direction in the magnet pockets of the rotor lamination core.

[0021] Furthermore, the invention relates to an electric machine having a rotor and a stator of the described type, wherein the rotor can be rotatably supported relative to the stator. The rotor can have a rotor shaft, and the stator can have a stator winding. The rotor lamination core can be connected to the rotor shaft in a rotationally fixed manner, for example by screwing or pressing. The rotor lamination core can be stamped and stacked, for example, by means of a metal rod that is guided through the rotor lamination core and pressed on both sides.

[0022] The rotor lamination core can also have end plates, each end plate being arranged on the axial side of the rotor lamination core. The end plates can be connected to the rotor lamination core by through screws. Alternatively, the end plates can be fixed to the rotor lamination core in another way, for example by adhesive bonding or stamping and stacking.

[0023] The invention also relates to a vehicle having at least one electric machine of this type, by means of which the vehicle can be driven. Description of the Drawings

[0024] The invention will be discussed below on the basis of exemplary embodiments with reference to the drawings. The drawings are schematic, wherein:

[0025] Figure 1 A sectional view of a rotor according to the invention is shown;

[0026] Figure 2 A top view of the rotor lamination is shown;

[0027] Figure 3 Details of the rotor lamination are shown, wherein the magnet is inserted into the magnet pocket;

[0028] Figure 4 Another exemplary embodiment of the rotor lamination is shown, in which magnets are inserted into magnet pocket portions;

[0029] Figure 5 Another exemplary embodiment of the rotor lamination is shown, in which magnets are inserted into magnet pocket portions; and

[0030] Figure 6 A vehicle having an electric machine according to the present invention is shown. Detailed Description

[0031] Figure 1 FIG. is a cross-sectional view of a rotor 1 for an electric machine. The rotor 1 includes a rotor lamination core 2, which is composed of a plurality of rotor laminations 3 stacked axially. The rotor lamination 3 has a central opening, and a rotor shaft 4 is press-fitted into the central opening in a rotationally fixed manner.

[0032] Figure 1 The rotor lamination core 2 is shown to have a through-opening 5. Magnet pocket portions 6 are arranged on the outer periphery of the rotor lamination core 2, and in these magnet pocket portions 6, a plurality of magnets are inserted in an axially stacked manner during installation.

[0033] Figure 2 A top view of a single rotor lamination 3 is schematically shown, which does not necessarily correspond to the details of the rotor laminations of the rotor lamination core 2 shown in Figure 1 The rotor lamination 3 includes magnet pocket portions 6, 7, which are arranged to be distributed circumferentially for magnets that are different in terms of their dimensions and shapes. The shape and number of the magnet pocket portions can vary with the number of magnetic poles of the rotor. The magnet pocket portions 6, 7 are provided in pairs. The rotor lamination 3 further includes a through-opening 5, which is arranged between the larger magnet pocket portions 6 and is used for screwing the rotor lamination core 2. Alternatively, end plates can be fixed to the rotor lamination core by adhesive bonding or stamping stacking.

[0034] Figure 3is a top view and shows details near the outer periphery of the rotor lamination core 2. The rotor lamination core 2, which is composed of stacked rotor laminations, has magnet pockets 8 into which magnets 9 are inserted. The magnet 9 has a basic cuboid shape, and two protrusions 11 are formed on its radially inward facing outer side 10, the protrusions having a triangular cross-section. Both of the two protrusions 11 are at a certain distance from the center of the edge of the magnet 9 facing the outer side 10. In the exemplary embodiment shown, the protrusions 11 extend over the entire axial length of the magnet 9. The dimensions of the magnet 9 with the protrusions 11 and the dimensions of the magnet pockets 8 are matched to each other taking into account tolerances, so that the magnet 9 inserted into the magnet pockets 8 is frictionally held there. On the one hand, the protrusions 11 contact the first inner side of the magnet pockets 8. The opposite outer side 12 of the magnet 9 contacts the second inner side of the magnet pockets 8. The magnet 9 can be inserted into the magnet pockets 8 with a very small force and is automatically held in that position. An additional position fixing process (e.g., by inserting a potting compound) is optional.

[0035] In a further production step, the previously unmagnetized magnets can be magnetized with an external magnetic field. This increases the magnetic attraction on the outer side 12 of the magnet 9 and its tendency to adhere precisely there.

[0036] Figure 4 is similar to Figure 3 and shows another exemplary embodiment of the rotor lamination core 2, in which a magnet 13 is inserted into the magnet pockets 8, and the protrusions 14 of the magnet pockets 8 are formed as hemispheres. In this exemplary embodiment, the protrusions 14 are exactly located on the edge of the outer side of the magnet 13. The protrusions 14 hold the magnet 13 in the radially outermost position, so that the magnetic field acting on the outside of the rotor is at a maximum.

[0037] Figure 5 is similar to Figure 3 and Figure 4 and shows the rotor lamination core 2 with a magnet 15, the protrusions 16 of the magnet 15 being of rectangular shape. The protrusions 16 are supported on the radially inner side of the magnet pockets 8. The outer side surface of the magnet 15 abuts against the inner side of the radially outer part of the magnet pockets 8.

[0038] Figure 6 shows a vehicle 17 having an electric motor 18, the electric motor 18 having a rotor 1 and a stator 20, the rotor 1 having a rotor shaft 19, and the stator 20 having a stator winding and surrounding the rotor 1. The electric motor 18 is used to drive the shaft of the vehicle 17.

[0039] List of reference numerals

[0040] 1 Rotor

[0041] 2 Rotor lamination core

[0042] 3 Rotor Laminations

[0043] 4 Rotor Shaft

[0044] 5 Through Opening

[0045] 6 Magnet Pocket

[0046] 7 Magnet Pocket

[0047] 8 Magnet Pocket

[0048] 9 Magnet

[0049] 10 Outer Side

[0050] 11 Protrusion

[0051] 12 Outer Side

[0052] 13 Magnet

[0053] 14 Protrusion

[0054] 15 Magnet

[0055] 16 Protrusion

[0056] 17 Vehicle

[0057] 18 Electric Motor

[0058] 19 Rotor Shaft

[0059] 20 Stator

Claims

1. A rotor (1) for an electric machine (18), having a rotor stack core (2), the rotor stack core (2) comprising a plurality of rotor laminations (3), the plurality of rotor laminations (3) being stacked in an axial direction and having a plurality of magnet pockets (6, 7, 8), the magnet pockets (6, 7, 8) being distributed circumferentially and forming recesses, magnets (9, 13, 15) being inserted into each recess, characterized in that, The magnets (9, 13, 15) have at least two protrusions (11, 14, 16) on the outer side (10).

2. The rotor according to claim 1, wherein the at least two protrusions (11, 14, 16) point radially inwards or radially outwards.

3. The rotor according to claim 1 or 2, wherein the at least two protrusions (11, 14, 16) are designed such that the outer side (12) of the magnets (9, 13, 15) positioned opposite the protrusions (11, 14, 16) is flush with the inner side of the magnet pockets (6, 7, 8).

4. The rotor according to any one of the preceding claims, wherein the two protrusions (11, 14, 16) arranged on the outer side (10) are at a distance from the edges of the magnets or are adjacent to the edges of the magnets (9, 13, 15).

5. The rotor according to any one of the preceding claims, wherein the protrusions (11, 14, 16) have a semi-circular or triangular or rectangular cross-section.

6. The rotor according to any one of the preceding claims, wherein the shape and size of the protrusions (11, 14, 16) are selected such that the magnets (9, 13, 15) are frictionally held in the magnet pockets (6, 7, 8).

7. The rotor according to any one of the preceding claims, wherein the rotor lamination core (2) is divided into a plurality of lamination core segments in the axial direction, and two adjacent lamination core segments are rotated relative to each other in the circumferential direction.

8. The rotor according to any one of the preceding claims, wherein the protrusions (11, 14, 16) extend over the entire axial length of the magnets (9, 13, 15) or over a part of the axial length of the magnets (9, 13, 15).

9. The rotor according to any one of the preceding claims, wherein the protrusions (11, 14, 16) are each arranged at the corners of the magnets (9, 13, 15).

10. The rotor according to any one of the preceding claims, wherein a plurality of magnets (9, 13, 15) are arranged continuously in the magnet pockets in the axial direction.

11. An electric machine (18) having a stator (20) and a rotor (1) according to any one of claims 1 to 10, the rotor (1) being rotatably mounted relative to the stator.

12. A vehicle (17) having at least one electric machine (18) according to claim 11, the vehicle (17) being drivable by means of the electric machine (18).

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