Rotor for motor and motor

Abstract

A rotor for an electric machine comprising an axis of rotation, a rotor core comprising a central rotor body and at least two rotor segments distributed circumferentially around the rotor body, a plurality of permanent magnets arranged between the rotor body and the rotor segments; a motor.

Description

[0001] The present application relates to a rotor for an electric machine, comprising a rotation axis, a rotor core comprising a central rotor body and at least two rotor segments circumferentially distributed around the rotor body, and a plurality of permanent magnets arranged between the rotor body and the rotor segments; and to an electric machine.

[0002] A rotor for an electric machine includes a plurality of permanent magnets and a rotor core defining pockets for accommodating magnet pairs between a hub portion and a pole portion. The transverse bridges of the rotor core extend between the outer surface and the radially outer end of the magnet pockets. The central bridge of the rotor core extends between adjacent magnet openings for accommodating magnet pairs. The central bridge and the transverse bridges provide structural integrity for the rotor and magnet retention. They are the result of hollowing out rotor laminations to produce pockets in which the magnets are distributed. The central bridge and the transverse bridges form the main electromagnetic flux leakage paths. In addition, the central bridge and the transverse bridges are subject to high mechanical stresses due to their reduced cross-sectional area.

[0003] US11152825 B2 discloses a rotor for an electric machine, comprising a magnet pair with a bridge region between the magnet pairs. The laminations comprising the rotor define openings in the bridge region between each pair of magnets. A first protrusion extends from a pole portion, and a second protrusion extends from a hub portion into the opening of the bridge region. A clip is installed in the opening, and a bonding material fills the remaining portion of the bridge region. The clip cooperates with the first protrusion, the second protrusion, and the bonding material to provide a structural connection between the hub portion and the pole portion.

[0004] DE 102017205858 A1 discloses a rotor for a permanent-magnet synchronous machine, comprising a rotor body and at least two permanent magnets, in which at least one recess extends at least partially through the rotor body essentially in the axial direction, the recess having at least two elongated first regions and at least one second region extending in the radial direction and radially between the two first regions, the permanent magnets being accommodated in each case in the first region, and the connecting element being accommodated in the second region and having at its respective end a geometric widening that conforms to the contour of the second region of the recess.

[0005] GB 2562704 A discloses a rotor comprising one or more slots between adjacent pole pairs and one or more windings in the one or more slots. A two-part retainer assembly is provided between the poles to hold the windings in place. The retainer comprises a root portion, preferably attached to the core using a fir-tree root type connection, and a cover portion for attaching to the root portion to hold the windings in place on the core.

[0006] GB 2546298 A discloses a rotor assembly having a rotor support hub, the rotor support hub comprising a plurality of first fir-tree connection members arranged around the periphery of the rotor support hub. The rotor assembly further comprises a plurality of rotor segments, each having a second connection member. Each second connection member may cooperate with at least one of the plurality of first connection members to connect each rotor segment around the periphery of the rotor support hub. A plurality of fixing members in the form of rolling pins are each configured to be accommodated between the cooperating first and second connection members and to form an inference fit therebetween so as to fix the rotor segment to the rotor support hub. The rotor segment and the support hub may comprise a plurality of laminations, wherein the rotor hub is a non-magnetic material.

[0007] One object is to reduce electromagnetic flux leakage via a central bridge and transverse bridges while maintaining the structural integrity of a rotor of an electric machine having a rotor core and a plurality of permanent magnets housed in the rotor core.

[0008] This object is achieved by a rotor for an electric machine according to claim 1. Further embodiments are subject to the dependent claims.

[0009] A rotor for an electric machine comprises a rotation axis, a rotor core comprising a central rotor body and at least two rotor segments distributed circumferentially around the rotor body, a plurality of permanent magnets arranged between the rotor body and the rotor segments, wherein the rotor body and the rotor segments are separated, and wherein a plurality of non-magnetic components form a coupling chain between the rotor body and the rotor segments.

[0010] Removing both the central bridge and the transverse bridge of the rotor advantageously improves the performance of the motor, allowing higher torque, higher power, and the ability to drive the motor at higher speeds. In order to provide structural integrity to the rotor core, the central bridge is replaced by non-magnetic members that form a link chain. The rotor core is separated into a rotor body and rotor segments, which means that the rotor core is not a monolithic component, but is assembled from multiple parts, and the rotor body and rotor segments must be connected by non-magnetic members.

[0011] According to one embodiment, the non-magnetic member is connected to the rotor body and the corresponding rotor segment by positive locking. In particular, the non-magnetic member is dovetailed to the rotor body and / or the corresponding rotor segment. In addition, the non-magnetic member can be connected to the rotor body and / or the corresponding rotor segment by a fir tree joint. It is known that the fir tree joint provides a plurality of contact areas, through which large thermal and centrifugal stresses can be advantageously transmitted. It provides an increased contact surface in the available space. The fir tree joint includes an arrangement of multiple pairs of opposite teeth or leaves extending from the trunk, which is also called a fir tree root. The teeth or leaves at the distal end of the trunk base have a smaller degree of lateral protrusion than the teeth or leaves located closer to the trunk base. The commonly used terminology is derived from the tapered form of the teeth or leaves, which has the appearance of a fir tree. The fir tree joint is conducive to establishing a connection between the rotor segment and the non-magnetic member because the connection is positioned at the narrowest point between the two permanent magnets of the magnet pair arranged in a V shape, where low space can be used for positive locking. The male fir-tree joint component at the rotor segment has a low circumferential extension and thereby fits into the narrow spaces between the permanent magnets. Therefore, the non-magnetic component comprises a complementary female fir-tree joint retaining recess having a low circumferential extension at its narrowest end. The connection between the non-metallic component and the rotor body can advantageously be a simpler dovetail connection, since there is more space for the connection between the permanent magnets. The dovetail connection can be wider in the circumferential direction, in particular with a male connector at the non-metallic component and a complementary female dovetail retaining recess at the rotor body. A further advantage of the dovetail joint is its lower radial extension compared to a fir-tree joint. The non-metallic component does not extend radially too far into the rotor body, thereby minimizing its influence on the magnetic flux in the rotor body.

[0012] The permanent magnets are arranged in magnet pairs between the rotor body and one of the corresponding rotor segments, so that the corresponding non-magnetic member extends in the radial direction between the corresponding two permanent magnets forming one of the magnet pairs. The area between the two permanent magnets forming the magnet pair is also referred to as the central bridge area. Since the rotor body is separated from the rotor segment, there is no rotor core material in the central bridge area. Instead, the non-magnetic member extends in the central bridge area. In addition, the area between the radial outer ends of the two permanent magnets forming one of the magnet pairs is referred to as the transverse bridge area, and there is no rotor core material in the transverse bridge area. The transverse bridge area and the central bridge area form a space between the rotor body and the corresponding rotor segment, which is partially occupied by the permanent magnets and the non-magnetic member. The remaining space can be filled with air. Alternatively, the space can be at least partially filled with epoxy resin or plastic composite filler.

[0013] According to a further embodiment, each rotor segment is wedge-shaped, the axially extending outer surface of the rotor segment forming a part of the circumferential surface of the rotor core. Two axially extending inner surfaces of the rotor segments abut against the respective magnet pairs, the inner surfaces enclosing an obtuse angle, in particular spanning between 100° and 140°. The rotor body may have a radially extending portion, which forms an intermediate portion of the circumferential surface of the rotor core between respective two adjacent rotor segments.

[0014] According to further embodiments, the rotor body and rotor segments of the rotor core consist of a plurality of axially stacked laminations. The non-magnetic component may be an extruded profile extending along the axial length of the rotor core or at least a portion of the axial length. The non-magnetic component may be made of aluminum, a metal matrix composite, a non-magnetic metal (particularly non-magnetic steel) or carbon fiber. The permanent magnets may be bonded to the rotor body and rotor segments by an adhesive.

[0015] According to a further embodiment, the rotor body has a frame structure with axially extending openings, wherein beams supporting the permanent magnets are connected to a circumferentially extending continuous hub ring.The number of rotor segments may be between six and ten.

[0016] Another aspect relates to an electric machine, which also achieves the above object. The electric machine comprises a rotor and a stator as described above, and the rotor can rotate relative to the stator around a rotation axis.

[0017] Embodiments of the rotor and the motor will be described with reference to the accompanying drawings, in which

[0018] Figure 1 An embodiment of a rotor is shown in perspective view;

[0019] Figure 2 Shows Figure 1 Magnified details of

[0020] Figure 3 Further enlarged details are shown in plan view;

[0021] Figure 4 An enlarged detail of a further embodiment of a rotor is shown in perspective view;

[0022] Figure 5 An embodiment of an electric machine is shown in a perspective exploded view;

[0023] Figure 6 The cross-sectional view shows Figure 5 Motor;

[0024] Figure 7 Shows Figure 6 Zoomed in details.

[0025] exist Figure 1, a rotor 1 for an electric machine is shown. The rotor 1 has a rotor shaft 18 and is rotatable about an axis of rotation L. The rotor core 6 includes a central rotor body 2 and eight circumferentially distributed rotor segments 3. The rotor body 2 and the rotor segments 3 are separate components, which are held together by non-magnetic components 4, which form a coupling chain between the rotor body 2 and the rotor segments 3. Permanent magnets 5 are arranged between the rotor body 2 and the rotor segments 3. The permanent magnets 5 are arranged in eight magnet pairs 7, each magnet pair being positioned between the rotor body 2 and one of the eight rotor segments 3. The rotor body 2 and the rotor segments 3 of the rotor core 6 are composed of a plurality of axially stacked laminations 14. The non-magnetic component 4 is an extruded profile, for example made of aluminum, which extends along the axial length of the rotor core 6.

[0026] exist Figure 2 In Figure 1 , which illustrates that the rotor body 2 has a radially extending portion 12, which forms an intermediate portion of the circumferential surface of the rotor core 6 between respective two adjacent rotor segments 3. The rotor body 2 further has a frame structure comprising an axially extending opening 17, in which beams 15 supporting the permanent magnets 5 are connected to a circumferentially extending continuous hub ring 16.

[0027] exist Figure 3 , further enlarged details are shown in a plan view, in which the axis of rotation L is oriented orthogonally with respect to the projection plane. The non-magnetic member 4 extends in the central bridge area, i.e. in the radial direction between the two magnets 5 forming one of the permanent magnet pairs 7. The material of the rotor core 6 has been removed or omitted from the central bridge area to reduce flux leakage. The space between the magnets 5 is filled with the non-magnetic member 4 and the epoxy or plastic composite filler 9. The non-magnetic member 4 is connected to the rotor body 2 and the rotor segment 3 by positive interlocking. In particular, the non-magnetic member 4 is connected to the rotor body 2 by a dovetail joint 22 and to the rotor segment 3 by a fir tree joint 23. The male fir tree structure at the rotor segment 3 extends radially between the permanent magnets 5 and is locked to the corresponding female fir tree structure at the non-magnetic member 4.

[0028] In addition, the material of the rotor core 6 has been removed or omitted from the transverse bridge area between the radially outer ends of the magnets and the outer surface 10 of the rotor core 6, which also advantageously reduces flux leakage. In the illustrated embodiment, the space between the rotor body 2 and the rotor segment 3 not occupied by the permanent magnets 5 and the non-magnetic components 4 is filled with an epoxy or plastic composite filler 9. The permanent magnets 5 can be bonded to the rotor body 2 and the rotor segment 3 by an adhesive so as to reduce the radial deformation of the rotor segment 3 under centripetal force, particularly at its peripheral end away from the non-magnetic component 4. The rotor segment 3 is wedge-shaped, and the axially extending outer surface 10 of the rotor segment 3 forms a part of the circumferential surface of the rotor core 6. The two axially extending inner surfaces 11 of the rotor segment 3 are close to the magnet pair 7, and the inner surfaces 11 enclose an obtuse angle of approximately 120°.

[0029] Figure 4 A further embodiment of the rotor 1 is illustrated in , which shows an enlarged detail in a perspective view. Again, material of the rotor core 6 has been removed or omitted from the central bridge area and the transverse bridge area to reduce flux leakage. In the embodiment shown, the space between the rotor body 2 and the rotor segments 3 that is not occupied by the permanent magnets 5 and the non-magnetic members 4 is partially filled with an epoxy or plastic composite filler 9 and partially filled with air 8. The epoxy or plastic composite filler 9 may include reinforced plastics, hybrid reinforcements and pre-impregnated materials for bonding and higher mechanical stiffness. It has been found that partially or completely filling the space with an epoxy or plastic composite filler 9 can reduce the elastic deformation of the rotor segments 3 by up to 25%, particularly near the transverse bridge areas. The non-magnetic members 4 are connected to the rotor body 2 by a dovetail joint 22 and to the rotor segments 3 by a fir tree joint 23.

[0030] exist Figure 5 , an embodiment of an electric machine is depicted in a perspective exploded view. Figure 6 The cross-sectional view shows Figure 5 The motor, and Figure 7 Shows Figure 6 . In the cross-sectional view, the overlapping hatching patterns of the magnet 5, the non-magnetic member 4 and the epoxy or plastic composite filler 9 do not imply the same materials. Figures 5 to 7 The motor includes a rotor 1 and a stator 19. The rotor 1 can rotate relative to the stator 19 about a rotation axis L. The stator 19 includes a winding 20 (which is Figure 5The rotor body 2 and the rotor segments 3 are separate components, which are held together by non-magnetic members 4 forming a coupling chain between the rotor body 2 and the rotor segments 3. The permanent magnets 5 are arranged between the rotor body 2 and the rotor segments 3. The space between the rotor body 2 and the rotor segments 3 that is not occupied by the permanent magnets 5 and the non-magnetic members 4 (including the lateral bridge area) is filled with an epoxy resin or plastic composite filler 9.

[0031] The rotation axis L defines an axial direction with respect to the rotor 1 and the electrical machine. Radial and circumferential directions are defined relative to the rotation axis L.

[0032] Reference numerals

[0033] 1 rotor

[0034] 2 Rotor body

[0035] 3 rotor segments

[0036] 4Non-magnetic components

[0037] 5 permanent magnets

[0038] 6 rotor core

[0039] 7 Magnet Pairs

[0040] 8 Air

[0041] 9 Filling

[0042] 10 External surface

[0043] 11Inner surface

[0044] 12 radial extension

[0045] 14 stacked laminations

[0046] 15 beam

[0047] 16 Hub ring

[0048] 17 Opening

[0049] 18 Rotor shaft

[0050] 19 stator

[0051] 20 Winding

[0052] 21 slots

[0053] 22 dovetail joint

[0054] 23 Fir Tree Joint

[0055] L Longitudinal axis

Claims

1. A rotor (1) for an electric motor, comprising: Axis of rotation (L), A rotor core (6) comprising a central rotor body (2) and at least two circumferentially distributed rotor segments (3), a plurality of permanent magnets (5), wherein the permanent magnets are arranged between the rotor body (2) and the rotor segments (3); The rotor body (2) and the rotor segments (3) are separated, and a plurality of non-magnetic components (4) form a linking chain between the rotor body (2) and the rotor segments (3).

2. The rotor according to claim 1, characterized in that The non-magnetic member (4) is connected to the rotor body (2) and the corresponding rotor segment (3) by positive locking.

3. A rotor according to any one of the preceding claims, characterised in that The non-magnetic member (4) is connected to the rotor body (2) and / or the corresponding rotor segment (3) by means of a dovetail joint (22) and / or a fir-tree joint (23).

4. The rotor according to claim 3, characterized in that The non-magnetic member (4) is connected to the rotor body (2) via a dovetail joint (22), wherein the corresponding rotor segment (3) is connected to the non-magnetic member (4) via a fir-tree joint (23).

5. A rotor according to any one of the preceding claims, characterised in that The permanent magnets (5) are arranged in magnet pairs (7) between the rotor body (2) and a respective one of the rotor segments (3), and the respective non-magnetic member (4) extends in a radial direction between the respective two magnets (5) forming one of the permanent magnet pairs (7).

6. A rotor according to any one of the preceding claims, characterised in that The space between the rotor body (2) and the respective rotor segment (3) not occupied by the permanent magnets (5) is at least partially filled with air (8).

7. A rotor according to any one of the preceding claims, characterised in that The space between the rotor body (2) and the respective rotor segment (3) not occupied by the permanent magnets (5) is at least partially filled with an epoxy or plastic composite filler (9).

8. A rotor according to any one of the preceding claims, characterised in that Each rotor segment (3) is wedge-shaped, with an axially extending outer surface (10) of the rotor segment forming part of the circumferential surface of the rotor core.

9. The rotor according to claim 8, characterized in that Two axially extending inner surfaces (11) of the rotor segment (3) abut against the corresponding magnet pair (7), the inner surfaces enclosing an obtuse angle, in particular spanning between 100° and 140°.

10. A rotor according to any one of the preceding claims 8 or 9, characterised in that The rotor body (2) has a radially extending portion (12) which forms a middle portion of the circumferential surface of the rotor core between respective two adjacent rotor segments (3).

11. A rotor according to any one of the preceding claims, characterised in that The rotor body (2) and the rotor segments (3) of the rotor core are composed of a plurality of axially stacked laminations (14).

12. A rotor according to any one of the preceding claims, characterised in that The non-magnetic member (4) is an extruded profile extending along the axial length of the rotor core.

13. A rotor according to any one of the preceding claims, characterised in that The non-magnetic member (4) is made of one of aluminum, metal matrix composite, non-magnetic metal and carbon fiber.

14. A rotor according to any one of the preceding claims, characterised in that The permanent magnets (5) are bonded to the rotor body (2) and the rotor segments (3) by adhesive.

15. A rotor according to any one of the preceding claims, characterised in that The rotor body (2) has a frame structure with an axially extending opening (17), wherein beams (15) supporting permanent magnets (5) are connected to a circumferentially extending continuous hub ring (16).

16. A rotor according to any one of the preceding claims, characterised in that The number of rotor segments (3) is between six and twelve.

17. An electrical machine comprising a rotor (1) according to any one of the preceding claims and a stator (19), the rotor being rotatable relative to the stator about a rotation axis (L).

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