Rotor for electric machine and method for producing rotor for electric machine

Abstract

A rotor for an electric machine has a core rotatable about an axis of rotation, the core having axially extending grooves; a plurality of magnets accommodated in the grooves; and at least one impeller arranged around the circumference of the axis of rotation; and a method of manufacturing a rotor for an electric machine.

Description

Technical Field

[0001] The present application relates to a rotor for an electric motor, the rotor having a core rotatable about a rotation axis, the core having an axially extending pocket, a plurality of magnets accommodated in the pocket, and at least one impeller arranged circumferentially around the rotation axis; and a method for manufacturing a rotor for an electric motor. Background Art

[0002] Critical component temperatures limit the performance of the electric machine because the insulation material begins to degrade above a threshold temperature.Cooling mechanisms for electric machines are known and include air agitation within an internal cavity of the electric machine.

[0003] US2015 / 0028727 A1 discloses a rotating electric machine cooling device, which includes a cooling fan provided at an axial end portion of a rotor and cooling fins provided at a core ring end portion, which are configured so that air is agitated by the agitation fan and circulates between the cooling fins. An air channel partition plate is positioned radially outside the cooling fan, forming a circulation path in which cooling air is blown out from the cooling fan, flows radially outward between the stator core and the air channel partition plate, and then flows radially inward and returns to the cooling fan, wherein the rotating electric machine includes a first air channel conversion member, which is provided radially outside of a gap between coil ends of circumferentially adjacent concentrated winding coils, and converts the cooling air blown out from the cooling fan and having flowed radially outward through the gap between the coil ends into an axially outward flow.

[0004] EP 2645548 A2 discloses a synchronous machine and a method for forming a rotor of an internal permanent magnet machine, the synchronous machine comprising: a rotor having a substantially cylindrical core with axially extending slots; a plurality of permanent magnets configured to define groups of alternating magnetic poles in a circumferential direction, the permanent magnets being located in corresponding ones of the slots; and a thermally conductive compound adjacent to the permanent magnets and the core for transferring heat from the permanent magnets; the method for forming a rotor of an internal permanent magnet machine comprises positioning a plurality of permanent magnets in corresponding plurality of axially extending magnet slots of the rotor core, and encapsulating the plurality of permanent magnets with the compound. Summary of the invention

[0005] An object of the present application may be to provide a rotor for an electric motor having enhanced cooling performance by air agitation, wherein formation of an agitation device is facilitated.

[0006] This object is achieved by a rotor for an electric machine according to claim 1 and a method for producing a rotor for an electric machine according to claim 18. Further embodiments are described in the dependent claims.

[0007] A rotor for an electric motor comprises: a core rotatable about a rotation axis, the core having an axially extending groove; a plurality of magnets received in the groove; an adhesive material encapsulating the magnets, the adhesive material forming a molded bonding fitting between the magnets and the core. At least one impeller is arranged around the circumference of the rotation axis at least at one axial end of the core, the impeller comprising a plurality of fins distributed along the circumference, wherein the impeller is a molded component molded integrally with the molded bonding fitting.

[0008] The impeller is advantageous in terms of heat extraction. As the heat transfer coefficient increases, the higher the velocity of the air, the more turbulent the airflow, and the more heat that can be extracted. Forming the impeller as a molded part molded integrally with the molded adhesive fitting advantageously provides an impeller that does not include additional parts on the rotor shaft or an arrangement where the impeller is disposed on the end plate of the rotor. The molded adhesive fitting encapsulating the magnets in the recess advantageously provides a substructure for a molded or overmolded impeller.

[0009] The impeller can be a molded part molded from a bonding material, which can be further molded together with a molded bonding part in a single injection. Alternatively, the impeller can be an overmolding part arranged on a molded bonding part in a separate injection, advantageously allowing the use of different materials. For example, the overmolding material for the impeller is an epoxy resin or a non-magnetic plastic-based composite material, which is advantageous in terms of electrical conductivity and mechanical properties. The impeller is self-supporting because it is neither arranged on the rotor shaft nor on the end plate of the rotor. The impeller is only connected to the molded bonding part that encapsulates the magnets.

[0010] According to one embodiment, the impeller comprises at least one ring connected to a molded adhesive fitting. The fins may be connected to the at least one ring. The fins may extend from the ring in an axial direction in a direction away from the core. The at least one ring may be molded to the molded adhesive fitting, and the fins may be molded or overmolded to the ring, thereby forming a gap between the fins and the core. The core comprises a central hub portion and a pole portion surrounding the hub portion. The fins may extend across the pole portion in a direction deviating from the radial direction, for example along a spiral path starting from a central axis of rotation.

[0011] According to another embodiment, the fin has an aerodynamic profile in cross section. An aerodynamic profile is a profile used for airfoils and similar structures. The aerodynamic profile may have a curved surface, such as a positive curved surface (which in aerodynamics means that its forward surface is more convex than the rearward surface) or a negative curved surface. In addition, the leading edge of the aerodynamic profile may be located at the radially inner end of the fin. The maximum thickness is closer to the leading edge than the trailing edge. Alternatively, the cross section may be wedge-shaped, wherein the radially inner end is thicker than the radially outer end.

[0012] According to another embodiment, the groove includes a central groove extension extending at least partially between two adjacent magnets of the plurality of magnets, the central groove extension being filled by molding or overmolding with a molded adhesive fitting. The central groove extension is a void connected to the groove that is not filled with magnets but filled with an adhesive material or a similar molding material to reduce flux leakage between two adjacent magnets. In addition, the groove includes a lateral groove extension extending at the lateral ends of the groove, the lateral groove extension being filled by molding or overmolding with a molded adhesive fitting. The impeller may include a first ring connected to the molded adhesive fitting in the central groove extension, and may further include a second ring connected to the molded adhesive fitting in the lateral groove extension. Thus, the first and second rings are arranged concentrically with respect to the axis of rotation, axially adjacent to the magnetic pole portion of the core. The second ring is arranged radially outside the first ring, and the fins may be connected to the first ring and the second ring. The fins may protrude in a radial direction on the second ring.The radially outward ends of the fins may extend radially as far as radially outside the core.

[0013] According to another embodiment, the grooves are arranged in an inner groove layer and an outer groove layer, the inner groove layer being arranged concentrically inside the outer groove layer. The radial distance to the rotation axis A of the inner groove layer is less than the radial distance to the rotation axis of the outer groove layer. The first ring can be connected to a molded adhesive fitting in a central groove extension of the groove arranged in the inner groove layer. The third ring can be connected to a molded adhesive fitting in a transverse groove extension of the groove arranged in the outer groove layer. The third ring is arranged radially outside the second ring, and the fins can be connected to the first ring, the second ring and the third ring. Alternatively, a first group of fins can be connected to the first ring and the second ring, and a second group of fins can be connected to the lock second ring and the third ring. In addition, the second ring can be connected to a molded adhesive fitting in a transverse groove extension of the inner groove layer, and to a molded adhesive fitting in a central groove extension of the outer groove layer. Furthermore, more than two concentric groove layers may be provided, wherein additional concentric rings are connected to molded adhesive fittings arranged in the center and / or in lateral groove extensions of corresponding grooves in further groove layers.

[0014] A method for manufacturing a rotor for an electric machine that solves this object comprises: positioning a plurality of magnets in axially extending grooves of a core; encapsulating the magnets with an adhesive material by forming a molded adhesive fitting between the magnets and the core; and forming at least one impeller arranged circumferentially around the axis of rotation of the core at least at one axial end of the core. The impeller is molded integrally with the molded adhesive fitting. According to one embodiment, the impeller is overmolded on the molded adhesive fitting. Additional features of the embodiments of the rotor as described above may form additional features of the method with respect to the corresponding basic manufacturing process steps. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Embodiments of a rotor for an electric machine will be illustrated with reference to the accompanying drawings, in which:

[0016] Figure 1 One embodiment of a rotor is shown in perspective view;

[0017] Figure 2 Shown along Figure 1 A plan view of the rotor in the axial direction;

[0018] Figure 3 Shown along Figure 2 Axial section of line CC in;

[0019] Figure 4 Separated in perspective view Figure 1 Parts of embodiments of the present invention;

[0020] Figure 5 Shown in perspective Figure 4 A sector of a part;

[0021] Figure 6 Shown in perspective Figure 4 Details of parts;

[0022] Figure 7 showing a rotor in perspective view;

[0023] Figure 8 Another embodiment of a rotor is shown in perspective view;

[0024] Fig. 9 Shown along Figure 8 A plan view of the rotor in the axial direction; and

[0025] Fig.10 Show Fig. 9 Zoomed in details. DETAILED DESCRIPTION

[0026] exist Figure 1 In FIG. 1 , a rotor 1 for an electric machine is shown. The rotor 1 has a rotor shaft 19 and a rotor core 2, which includes stacked laminations fixed in the axial direction and fixed to the rotor shaft 19 by end plates 20 arranged at the axial ends of the core 2. Two impellers 9 are arranged at the two axial ends of the core 2, radially outside the end plates 20. In FIG. Figure 7 , an exemplary core 2 is shown without an impeller and an end plate to illustrate an axially extending groove 8 and a plurality of magnets 3 accommodated in the groove 8. The groove 8 includes a central groove extension 7 extending at least partially between two adjacent magnets 3 of the plurality of magnets 3. The groove 8 further includes a lateral groove extension 16 extending at the lateral ends of the groove 8. The core 2 includes a central hub portion 4 and a pole portion 5 surrounding the hub portion 4. An opening 17 extends through the core 2 in the axial direction.

[0027] exist Figure 2 In the figure, it is shown that Figure 1 A plan view of the rotor in the axial direction. Figure 3 In the figure, it is shown that Figure 2 The axial section of the line CC in FIG. is described together as follows Figure 1 , 2 and 3. The core 2 is rotatable about a rotation axis A. The rotation axis A defines an axial direction with respect to the rotor 1. A radial direction and a circumferential direction are defined relative to the rotation axis A. The adhesive material encapsulates the magnet 3 ( Figure 7), the adhesive material forms a molded adhesive fitting 6 between the magnet 3 and the core 2. The impeller 9 at the two axial ends of the core 2 includes a plurality of fins 10 distributed circumferentially around the rotation axis A. Only one fin 10 is provided with a reference number. The impeller 9 is a molded component molded integrally with the molded adhesive fitting 6. The impeller 9 can be a molded component molded together with the molded adhesive fitting 6 by the adhesive material, or the impeller 9 can be an overmolding provided on the molded adhesive fitting 6. The impeller 9 includes a first ring 11 and a second ring 12 connected to the molded adhesive fitting 6. The fins 10 are connected to the first ring 11 and the second ring 12. The first ring 11 and the second ring 12 extend coaxially and extend away from the core 2 in the axial direction. The core 2 includes a central hub portion 4 and a magnetic pole portion 5 surrounding the hub portion 4, and an opening 17 extends through the core 2 in the axial direction in a boundary area between the magnetic pole portion 5 and the hub portion 4. The fins 10 extend in a direction deviating from the radial direction, for example along a helical path, across the pole portion 5. The fins 10 protrude in the radial direction over the second ring 12 to a radial extension corresponding to the radially outer face 18 of the core 2.

[0028] exist Figure 4 In the Figure 1 The rotor 1 comprises a molded bonded fitting 6 and two impellers 9. Obviously, the impellers 9 are self-supporting and are only connected to the molded bonded fitting 6. The fins 10 have an aerodynamic profile in cross section (ie in a section orthogonal to the axis of rotation A). Figure 5 Further describing the aerodynamic profile, Figure 5 Shown in perspective Figure 4 The aerodynamic profile has a positive curvature, i.e. the forward surface 21 of the fin 10 is more convex than the rearward surface 22. The leading edge of the aerodynamic profile is arranged at the radially inward end 14 of the fin 10. The maximum thickness of the profile is located closer to the leading edge than to the trailing edge.

[0029] exist Figure 6 In the perspective view, the Figure 4 Further details of the molded bonded fitting 6 and the two impellers 9. Figure 8 To describe Figure 6 , Figure 8 Shows that there is no Figure 6 The core 2 depicted in FIG. The groove 8 includes a central groove extension 7 extending at least partially between two adjacent magnets 3 of the plurality of magnets 3. The central groove extension 7 is filled by being molded or overmolded integrally with the molded adhesive fitting 6. The groove 8 further includes a lateral groove extension 16 extending at the lateral ends of the groove 8. The lateral groove extension 16 is also filled by being molded or overmolded integrally with the molded adhesive fitting 6. Reference Figure 5 and Figure 6 , the impeller 9 comprises a first ring 11 connected to the molded adhesive fitting 6 in the central groove extension 7, and the impeller 9 comprises a second ring 12 connected to the molded adhesive fitting 6 in the lateral groove extension 16. The fins 10 protrude in the radial direction on the second ring 12. The second ring 12 is arranged radially with respect to the reference first ring 11. Figures 4 to 7 A method of manufacturing a rotor 1 for an electric machine is described below. The method comprises the steps of positioning a plurality of magnets 3 in axially extending grooves 8 of a core 2, encapsulating the magnets 3 with an adhesive material by forming a molded adhesive fitting 6 between the magnets 3 and the core 2, and thereby also filling the central groove extension 7 and the lateral groove extensions 16. By overmolding the molded adhesive fitting 6, an impeller 9 is integrally formed at an axial end of the core 2.

[0030] exist Figure 8 In FIG. 1 , another embodiment of a rotor 1 is shown in a perspective view. Fig. 9 Depicted along Figure 8 A plan view of the rotor in the axial direction, and Fig.10 It is shown in Fig. 9 will be described together with Figure 8 , Fig. 9 and Fig.10 . This embodiment differs from the previously described embodiment in that the grooves 8 are arranged in the inner groove layer 23 and the outer groove layer 24, the inner groove layer 23 being arranged concentrically inside the outer groove layer 24. The grooves are evenly distributed in the inner groove layer 23 and the outer groove layer 24. Therefore, a third ring 25 is provided, which is connected to the molded adhesive fitting 6 in the lateral groove extension 16 of the outer groove layer 24. The second ring 12 is connected to the molded adhesive fitting 6 in the lateral groove extension 16 of the inner groove layer 23 and to the molded adhesive fitting 6 in the central groove extension 7 of the outer groove layer 24. In addition, the fins 10 are divided into a first group 26 and a second group 27. The first group 26 fins 10 are connected to the first ring 11 and the second ring 12, and the second group 27 fins 10 are connected to the second ring 12 and the third ring 25. The fins 10 of the second group 27 are arranged so that they have a different angle of attack than the fins 10 of the first group 26.

[0031] Reference Number

[0032] 1 Rotor

[0033] 2 Core

[0034] 3 Magnets

[0035] 4 Hub part

[0036] 5 Magnetic pole part

[0037] 6 Molded adhesive parts 7 Center groove extension 8 Grooves

[0038] 9 Impeller

[0039] 10 Fins

[0040] 11 First Ring

[0041] 12 Second Ring

[0042] 14 Radially inward end 15 Radially outward end 16 Transverse groove extension 17 Opening

[0043] 18 Radial outside

[0044] 19 Axis

[0045] 20 End plate

[0046] 21 Forward surface

[0047] 22 Backward surface

[0048] 23 inner groove layer

[0049] 24 Outer groove layer

[0050] 25 Third Ring

[0051] 26 First set of fins 27 Second set of fins A Rotation axis

Claims

1. A rotor for an electric motor, the rotor (1) comprising: A core (2) rotatable about an axis of rotation (A), the core having an axially extending groove (8); a plurality of magnets (3) received in the grooves (8); an adhesive material encapsulating the magnet (3), the adhesive material forming a molded bonded fitting (6) between the magnet (3) and the core (2); at least one impeller (9) at least at one axial end of the core (2), the impeller comprising a plurality of fins (10) distributed circumferentially around the axis of rotation (A); It is characterized in that The impeller (9) is a molded part molded integrally with the molded adhesive fitting (6).

2. The rotor according to claim 1, characterized in that The impeller (9) is an overmolding arranged on the molded adhesive fitting (6).

3. A rotor according to any one of the preceding claims, characterised in that The overmoulding material used for the impeller (9) is an epoxy-based resin.

4. A rotor according to any one of the preceding claims, characterised in that The impeller (9) is self-supporting.

5. A rotor according to any one of the preceding claims, characterised in that The impeller (9) comprises at least one ring (11, 12) connected to the molded adhesive fitting (6).

6. The rotor according to claim 5, characterized in that The fin (10) is connected to the at least one ring (11, 12).

7. Rotor according to one of the preceding claims 5 or 6, characterized in that The fin (10) extends in an axial direction from the at least one ring (11, 12) in a direction away from the core (2).

8. A rotor according to any one of the preceding claims, characterised in that The core (2) comprises a central hub portion (4) and a pole portion (5) surrounding the hub portion (4), wherein the fin (10) extends across the pole portion (5) in a direction deviating from a radial direction.

9. A rotor according to any one of the preceding claims, characterised in that The fin (10) has an aerodynamic profile in cross section.

10. The rotor according to claim 9, characterized in that The aerodynamic profile has a curved surface.

11. The rotor according to claim 9, characterized in that The leading edge of the aerodynamic profile is located at the radially inward end (14) of the fin (10).

12. A rotor according to any one of the preceding claims, characterised in that The groove (8) comprises a central groove extension (7) extending at least partially between two adjacent magnets (3) of the plurality of magnets (3), the central groove extension (7) being filled by being integrally molded or overmolded with the molded adhesive fitting (6).

13. A rotor according to any one of the preceding claims, characterised in that The groove (8) comprises a transverse groove extension (16) extending at a transverse end of the groove (8), the transverse groove extension (16) being filled by being molded or overmolded integrally with the molded adhesive fitting (6).

14. A rotor according to any one of the preceding claims 12 or 13, characterised in that The impeller (9) comprises a first ring (11) connected to a moulded bonded fitting (6) in the central groove extension (7).

15. A rotor according to any one of the preceding claims 12 to 14, characterised in that The impeller (9) comprises a second ring (12) connected to a moulded bonded fitting (6) in the transverse groove extension (16).

16. A rotor according to any one of the preceding claims 12 to 15, characterised in that The fins (10) protrude in a radial direction on the second ring (12).

17. A rotor according to any one of the preceding claims 12 to 16, characterised in that The second ring (12) is arranged radially outside the first ring (11), and the fin (10) is connected to the first ring (11) and the second ring (12).

18. A rotor according to any one of the preceding claims 12 to 16, characterised in that The groove (8) is arranged in an inner groove layer (23) and an outer groove layer (24), the inner groove layer being arranged concentrically inside the outer groove layer, wherein the first ring (11) is connected to a molded adhesive fitting (6) in a central groove extension (7) of the inner groove layer (23), and the third ring (25) is connected to a molded adhesive fitting (6) in a lateral groove extension (16) of the outer groove layer (24).

19. The rotor according to claim 18, characterized in that The second ring (12) is connected to a molded adhesive fitting (6) in the lateral groove extension (16) of the inner groove layer (23) and a molded adhesive fitting (6) in the central groove extension (7) of the outer groove layer (24).

20. A rotor according to any one of the preceding claims 18 or 19, characterised in that A first group (26) of fins (10) can be connected to the first ring (11) and the second ring (12), and a second group (27) of fins (10) can be connected to the second ring (12) and the third ring (25).

21. A method for manufacturing a rotor (1) for an electric machine, comprising: Positioning a plurality of magnets (3) in axially extending grooves (8) of the core (2); encapsulating the magnet (3) with an adhesive material by forming a molded adhesive fitting (6) between the magnet (3) and the core (2); At least one impeller (9) is formed at least at one axial end of the core, the impeller (9) having a plurality of fins (10) distributed along a circumference around a rotation axis (A); It is characterized in that The impeller (9) is molded integrally with the molded adhesive fitting (6).

22. The method according to claim 20, characterized in that The impeller (9) is over-molded onto the molded adhesive fitting (6).

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