Rotor core, rotor, and electric motor

Abstract

A rotor core according to the present disclosure has a magnet slot into which a magnet is inserted. The rotor core comprises: an outer core that is cylindrical and is not split in the circumferential direction; an inner core that is disposed inward of the outer core and which has a magnet slot provided between the inner core and the outer core; and an engagement part that causes the outer core and the inner core to divisibly engage with each other such that the outer core does not move in the circumferential direction or the radial direction of the outer core with respect to the inner core. The division surface of the outer core and the division surface of the inner core are positioned inward of the magnet slot.

Description

Rotor core, rotor and electric motor

[0001] The present disclosure relates to a rotor core, a rotor including this rotor core, and an electric motor including this rotor.

[0002] Conventionally, the rotor of an electric motor includes a rotor core rotatably mounted on a shaft, a plurality of magnets mounted on the rotor core, and a pair of plate-shaped end plates mounted on both axial ends of the rotor core. Such electric motors often use magnets containing heavy rare earth elements. Heavy rare earth elements are a finite and scarce resource, and are only produced in a limited number of countries, posing a risk of international issues such as resource depletion and country risk. In recent years, there have been moves to reduce the use of heavy rare earth elements as a countermeasure. However, in reality, little progress has been made in recycling magnets incorporated into products such as electric motors.

[0003] Republished WO2015 / 189938

[0004] The reasons why recovery of magnets built into electric motors has not progressed include the fact that the magnets built into electric motors are magnetic, are fixed to the rotor core with adhesives, and are easily broken. For these reasons, it is not easy to remove magnets once they are built into the motor.

[0005] By solving these problems, magnets can be recycled efficiently, and the depletion of resources and the risk of international issues can be avoided through the effective use of resources. This will enable a permanently stable supply of servo motors.

[0006] In order to solve the above-mentioned problems, a rotor core, a rotor, and an electric motor are desired that allow magnets incorporated in the electric motor to be easily removed.

[0007] The rotor core of the present disclosure is a rotor core having magnet slots into which magnets are inserted, and comprises a cylindrical outer core that is not divided circumferentially, an inner core that is arranged inside the outer core and has the magnet slot between it and the outer core, and an engaging portion that engages the outer core and the inner core in a separable manner so that the outer core does not move circumferentially or radially relative to the inner core, and the dividing surface of the outer core and the dividing surface of the inner core are located inside the magnet slots.

[0008] The rotor of the present disclosure includes the rotor core of the present disclosure described above and the magnets inserted into the magnet slots.

[0009] The electric motor of the present disclosure includes the rotor of the present disclosure described above, and a stator disposed outside the rotor so as to form a cylindrical gap between the rotor and the stator.

[0010] 1 is a schematic front view showing an electric motor according to one embodiment of the present invention; FIG. 2 is a schematic exploded perspective view showing a first embodiment of a rotor that can be used in an electric motor according to one embodiment of the present invention; FIG. 3 is a schematic front view showing a rotor according to the first embodiment, partially enlarged; FIG. 4 is a schematic front view showing a rotor according to a second embodiment, partially enlarged; FIG. 5 is a schematic perspective view showing a rotor according to the second embodiment, partially enlarged; FIG. 6 is a schematic longitudinal sectional view showing a rotor according to the second embodiment, partially enlarged; FIG. 7 is a schematic front view showing a rotor according to a third embodiment; FIG. 8 is a schematic exploded perspective view showing a rotor according to the third embodiment; FIG. 9 is a schematic front view showing a rotor according to the third embodiment, partially enlarged; FIG. 10 is a schematic front view showing a first modified example of the rotor according to the first embodiment, partially enlarged; FIG. 11 is a schematic front view showing a second modified example of the rotor according to the first embodiment, partially enlarged; FIG. 12 is a schematic front view showing a third modified example of the rotor according to the first embodiment, partially enlarged;

[0011] An embodiment of the present disclosure will be described below with reference to the drawings. An electric motor 1 according to one embodiment of the present invention will be described with reference to Fig. 1 . The electric motor 1 includes a stator 2 and a rotor 3. In the following description, the axial direction J1 (see Fig. 2 ) is defined as the front-rear direction. One end of the axial direction J1 is defined as the front side J11, and the other end of the axial direction J1 is defined as the rear side J12.

[0012] The stator 2 is cylindrical and includes a stator core 4 and a coil 5. The stator core 4 is cylindrical with both ends in the axial direction J1 open and made of a magnetic material. Typically, the stator core 4 has a structure including a plurality of electromagnetic steel plates. The plurality of electromagnetic steel plates are stacked in the axial direction J1. The stator core 4 has a plurality of teeth (not shown) that protrude radially inward from its inner circumferential surface. Each of the plurality of teeth extends along the axial direction J1 of the stator core 4. The plurality of teeth are arranged in a line in the circumferential direction of the stator core 4. A coil 5 is attached to each of the plurality of teeth. When attached to the stator core 4, the coil 5 protrudes forward from the front end face of the stator core 4 and protrudes rearward from the rear end face of the stator core 4.

[0013] The rotor 3 is cylindrical and includes a rotor core 6 and a plurality of magnets 7. The rotor core 6 has magnet slots 8 into which the magnets 7 are inserted. As shown in Figures 1 to 3 , the rotor core 6 includes a cylindrical outer core 9, a cylindrical inner core 10, and engagement portions (in this embodiment, an insertion portion 13 of the outer core 9 and an inserted portion 14 of the inner core 10; details will be described later).

[0014] The outer core 9 is cylindrical with both ends in the axial direction J1 open, and is made of a magnetic material. Typically, the outer core 9 has a structure including a plurality of electromagnetic steel plates. The plurality of electromagnetic steel plates are stacked in the axial direction J1. The outer core 9 has a plurality of recesses 11 on its inner peripheral surface. The recesses 11 are generally rectangular in front view, and open radially inward of the outer core 9. The recesses 11 extend along the axial direction J1 of the outer core 9. Both ends of the recesses 11 in the axial direction J1 open outward. The plurality of recesses 11 are arranged side by side in the circumferential direction of the outer core 9.

[0015] With this configuration, the outer core 9 has multiple protrusions 12 that protrude radially inward from its inner circumferential surface. The protrusions 12 are located between adjacent recesses 11, 11. Each of the multiple protrusions 12 extends along the axial direction J1 of the outer core 9. The multiple protrusions 12 are arranged side by side in the circumferential direction of the outer core 9. Each of the multiple protrusions 12 is provided with an insertion portion 13 that is inserted into the inner core 10 (described later). The insertion portion 13 protrudes radially inward from the tip of the protrusion 12. The insertion portion 13 extends along the axial direction J1 of the outer core 9. In the illustrated example, the insertion portion 13 has a generally circular shape in a front view and has an outer diameter that is larger than the width of the tip of the protrusion 12 in a front view. Therefore, the insertion portion 13 closes the end of the opening of the recess 11 to reduce the size of the opening. The outer core 9 configured in this manner is formed so as not to be divided in the circumferential direction. Since the outer core 9 is not divided in the circumferential direction, it has stronger strength during rotation than a configuration in which it is divided in the circumferential direction. In addition, the number of parts of the outer core 9 can be reduced, and assembly and disassembly of the rotor 3 can be made efficient.

[0016] The inner core 10 has a rectangular cylindrical shape with both ends open in the axial direction J1 and is made of a magnetic material. Typically, the inner core 10 has a structure including multiple electromagnetic steel plates. The multiple electromagnetic steel plates are stacked in the axial direction J1. The inner core 10 has multiple insertion receiving portions 14 on its outer surface into which the insertion portions 13 of the outer core 9 are inserted. The insertion receiving portions 14 are recessed inward from the outer surface of the inner core 10 and extend along the axial direction J1 of the inner core 10. Both ends of the insertion receiving portions 14 in the axial direction J1 open outward. In the illustrated example, since the insertion portions 13 are circular in a front view, the insertion receiving portions 14 are also circular in a front view. A shaft (not shown) of the electric motor 1 is passed through an inner hole 15 of the inner core 10. The inner core 10 is fixed to the shaft so as to be rotatable integrally with the shaft.

[0017] As shown in Fig. 1 , the inner core 10 is disposed inside the outer core 9. The inner core 10 is disposed inside the outer core 9, for example, by fitting the outer core 9 into the inner core 10 from one end side in the axial direction J1. When the outer core 9 is fitted into the inner core 10, the inserting portion 13 of the outer core 9 is inserted into the inserted portion 14 of the inner core 10. With the inner core 10 disposed inside the outer core 9, the opening of the recess 11 of the outer core 9 is blocked by the outer surface of the inner core 10. This forms a plurality of magnet slots 8 penetrating in the axial direction J1 between the inner core 10 and the outer core 9.

[0018] As described above, with the inner core 10 disposed inside the outer core 9, the inserting portion 13 of the outer core 9 is inserted into the inserted portion 14 of the inner core 10. In this manner, the outer core 9 and the inner core 10 are separably engaged. Therefore, the inserting portion 13 of the outer core 9 and the inserted portion 14 of the inner core 10 constitute an engaging portion that separably engages the outer core 9 and the inner core 10. As described above, the inserting portion 13 and the inserted portion 14 are circular in front view. Therefore, the engaging portion can engage the outer core 9 and the inner core 10 so that the outer core 9 does not move relative to the inner core 10 in the circumferential direction of the outer core 9 or the radial direction of the outer core 9 when the rotor 3 rotates.

[0019] Because the outer core 9 and the inner core 10 are separable, the outer core 9 and the inner core 10 each have a dividing surface. The dividing surface of the outer core 9 is a surface that contacts the inner core 10 when the outer core 9 and the inner core 10 are engaged. The dividing surface of the inner core 10 is a surface that contacts the outer core 9 when the outer core 9 and the inner core 10 are engaged. In other words, when the outer core 9 and the inner core 10 are engaged, the dividing surface of the outer core 9 contacts the dividing surface of the inner core 10. Note that "contact" here includes cases where the surfaces of the outer core 9 and the inner core 10 are in complete contact, as well as cases where there is a small gap between the surfaces of the outer core 9 and the inner core 10. Because the outer core 9 and the inner core 10 are configured to be separable, there is a risk that a small gap will inevitably occur between the surfaces of the outer core 9 and the inner core 10, unlike when the outer core 9 and the inner core 10 are integrally formed.

[0020] In the illustrated example, the dividing surface of the outer core 9 includes the outer surface of the tip of the protruding portion 12 and the outer peripheral surface of the insertion portion 13. The dividing surface of the inner core 10 is the surface where the outer surface of the tip of the protruding portion 12 and the outer peripheral surface of the insertion portion 13 come into contact. In other words, the dividing surface of the inner core 10 includes the inner surface of the opening of the insertion receiving portion 14 and the inner peripheral surface of the insertion receiving portion 14. With this configuration, the dividing surfaces of the outer core 9 and the inner core 10 are located inside the magnet slots 8.

[0021] The magnet 7 has a substantially rectangular plate shape. The magnet 7 is provided in a magnet slot 8 formed in the rotor core 6. Specifically, the magnet 7 is inserted into the magnet slot 8 with one plate surface of the magnet 7 facing the inner circumferential surface of the outer core 9 and the other plate surface of the magnet 7 facing the outer surface of the inner core 10. The magnet 7 is fixed to the rotor core 6 with a thermoplastic resin. In this embodiment, the magnet 7 is a neodymium magnet.

[0022] As described above, the dividing surfaces of the outer core 9 and the inner core 10 are located inside the magnet slot 8. Therefore, as shown in Figure 3, the dividing surfaces of the outer core 9 and the inner core 10 are not located in part A of the outer core 9 through which the magnetic flux of the magnet 7 inserted in the magnet slot 8 passes. Here, part A through which the magnetic flux of the magnet 7 passes is the part of the outer core 9 outside the magnet 7 provided in the magnet slot 8. Note that the arrows in Figure 3 indicate the magnetic flux of the magnet 7.

[0023] 1, the rotor 3 is disposed inside the cylindrical stator 2. Specifically, the stator 2 is disposed outside the rotor 3 so as to form a cylindrical gap 16 between it and the outer peripheral surface of the rotor 3. In other words, the stator 2 is disposed outside the outer core 9 of the rotor 3, with the cylindrical gap 16 interposed therebetween, so as to surround the outer peripheral surface of the outer core 9.

[0024] In the embodiment configured as described above, the outer core 9 and the inner core 10 are separably engaged by the engaging portion, allowing the outer core 9 to be easily removed from the inner core 10. During this process, the rotor 3 is exposed to high temperatures to demagnetize the magnets and remove the thermoplastic resin. In addition, the dividing surfaces of the outer core 9 and the inner core 10 are located inside the magnet slots 8 so as not to be located in the area A through which the magnetic flux of the magnet 7 passes. A small gap may inevitably occur between the dividing surfaces of the outer core 9 and the inner core 10. If this small gap were located in the area A through which the magnetic flux of the magnet 7 passes, it would impede the flow of magnetic flux, resulting in a decrease in the performance of the electric motor 1. However, in this embodiment, as described above, the dividing surfaces of the outer core 9 and the inner core 10 are not located in the area A through which the magnetic flux of the magnet 7 passes, so there is no risk of a decrease in the performance of the electric motor 1.

[0025] Next, a rotor 3 according to a second embodiment will be described with reference to Figures 4 to 6. Note that components having the same reference numerals as those in the first embodiment have the same functions, and therefore their description may be omitted below. The rotor 3 of the second embodiment differs from the first embodiment mainly in the configuration of the outer core 9.

[0026] The rotor 3 of the second embodiment has a flux barrier 17. In the illustrated example, the flux barrier 17 is provided on the outer core 9 so as to penetrate in the axial direction J1. The flux barrier 17 is located at both ends of the recess 11 of the outer core 9. The flux barrier 17 communicates with the recess 11 of the outer core 9. In other words, the flux barrier 17 is located at both ends of the magnet slot 8 while communicating with the magnet slot 8. In this case, part or all of the flux barrier 17 is not located in the portion A through which the magnetic flux of the magnet 7 passes. In this way, the flux barrier 17 is provided in a portion through which the magnetic flux of the magnet 7 inserted in the magnet slot 8 does not pass, and in a position in contact with the magnet slot 8.

[0027] 5 and 6 , the length of the outer core 9 in the axial direction J1 and the length of the inner core 10 in the axial direction J1 are greater than the length of the magnet 7 in the axial direction J1. Therefore, when the magnet 7 is arranged in the magnet slot 8, a space 18 without the magnet 7 is provided on one end side of the magnet slot 8 in the axial direction J1, and a space 18 without the magnet 7 is provided on the other end side of the magnet slot 8 in the axial direction J1.

[0028] In this embodiment, the rotor core 6 and the magnets 7 are fixed using thermoplastic resin 20. When fixing the magnets 7 to the rotor core 6, the molten thermoplastic resin 20 is poured into the flux barriers 17 and the spaces 18. The thermoplastic resin 20 poured into the flux barriers 17 and the spaces 18 then hardens, fixing the magnets 7 to the rotor core 6. Therefore, the thermoplastic resin 20 is filled into the magnet slots 8 at both ends of the rotor core 6 in the axial direction J1 so as to cover the end faces 19 of the magnets 7 located at both ends of the axial direction J1, and is also filled into the flux barriers 17. With the above-mentioned configuration, the thermoplastic resin 20 can prevent the magnets 7 from slipping out of the magnet slots 8 in the axial direction J1.

[0029] Next, a rotor 3 according to a third embodiment will be described with reference to Figures 7 to 9. Note that components having the same reference numerals as those in the first embodiment have the same functions, and therefore their descriptions may be omitted below. The rotor 3 of the third embodiment differs from the first embodiment mainly in the configurations of the outer core 9 and the inner core 10.

[0030] The cylindrical outer core 9 has a plurality of grooves 21 on its inner circumferential surface. The grooves 21 are generally trapezoidal in front view, and their width increases radially inward of the outer core 9. The grooves 21 open radially inward of the outer core 9. The grooves 21 extend along the axial direction J1 of the outer core 9. Both ends of the grooves 21 in the axial direction J1 open outward. The plurality of grooves 21 are arranged side by side in the circumferential direction of the outer core 9. Both side surfaces of the grooves 21 of the outer core 9 have recesses 11. The recesses 11 are generally rectangular in front view, and open into the grooves 21. The recesses 11 extend along the axial direction J1 of the outer core 9. Both ends of the recesses 11 in the axial direction J1 open outward.

[0031] With this configuration, the outer core 9 has a plurality of protrusions 22 that protrude radially inward from its inner circumferential surface. The protrusions 22 are located between adjacent grooves 21, 21. Each of the plurality of protrusions 22 extends along the axial direction J1 of the outer core 9. The plurality of protrusions 22 are arranged side by side in the circumferential direction of the outer core 9. Each of the plurality of protrusions 22 is provided with an insertion portion 13 that is inserted into the inner core 10. The insertion portion 13 protrudes radially inward from the tip of the protrusion 22 of the outer core 9. The insertion portion 13 extends along the axial direction J1 of the outer core 9. In the illustrated example, the insertion portion 13 has a generally circular shape in a front view.

[0032] The inner core 10 has a cylindrical main body 23 and multiple protrusions 24. The main body 23 is cylindrical and extends in the axial direction J1, with both ends in the axial direction J1 open. A shaft (not shown) of the electric motor 1 is passed through the inner hole 15 of the main body 23. The main body 23 is fixed to the shaft so as to be rotatable integrally with the shaft. The multiple protrusions 24 are provided on the outer peripheral surface of the main body 23. The protrusions 24 protrude radially outward from the outer peripheral surface of the main body 23. The protrusions 24 are generally trapezoidal plate-shaped when viewed from the front, and their width decreases toward the tip when viewed from the front. The multiple protrusions 24 are arranged side by side in the circumferential direction of the main body 23.

[0033] The inner core 10 has a plurality of insertion receiving portions 14 into which the insertion portions 13 of the outer core 9 are inserted. The insertion receiving portions 14 are provided on the outer surface of the main body portion 23 between adjacent protrusions 24, 24. The insertion receiving portions 14 are recessed inward from the outer surface of the main body portion 23 and extend along the axial direction J1. Both ends of the insertion receiving portions 14 in the axial direction J1 are open outward. In the illustrated example, since the insertion portions 13 are circular in a front view, the insertion receiving portions 14 are also circular in a front view.

[0034] As shown in Figure 7, the inner core 10 is disposed inside the outer core 9. The inner core 10 is disposed inside the outer core 9, for example, by fitting the outer core 9 into the inner core 10 from one end side in the axial direction J1. When the outer core 9 is fitted into the inner core 10, the inserting portion 13 of the outer core 9 is inserted into the inserted portion 14 of the inner core 10, and the convex portion 24 of the inner core 10 is inserted into the groove portion 21 of the outer core 9. With the inner core 10 disposed inside the outer core 9, the opening of the concave portion 11 of the outer core 9 is blocked by the convex portion 24 of the inner core 10. As a result, a plurality of magnet slots 8 penetrating in the axial direction J1 are provided between the inner core 10 and the outer core 9.

[0035] In the illustrated example, the dividing surfaces of the outer core 9 include the outer surface of the tip of the protruding portion 22, the outer peripheral surface of the insertion portion 13, and the bottom surface of the groove 21. The dividing surfaces of the inner core 10 are the surfaces where the outer surface of the tip of the protruding portion 22, the outer peripheral surface of the insertion portion 13, and the bottom surface of the groove 21 come into contact. That is, the dividing surfaces of the inner core 10 include the inner surface of the opening of the insertion receiving portion 14, the inner peripheral surface of the insertion receiving portion 14, and the tip surface of the protruding portion 24. With this configuration, the dividing surfaces of the outer core 9 and the inner core 10 are located inside the magnet slot 8. That is, the dividing surfaces of the outer core 9 and the inner core 10 are located in parts that are not passed by the magnetic flux of the magnet 7 inserted in the magnet slot 8.

[0036] With the above-described configuration, even when the magnets 7 are arranged in an approximately V-shape, the inner core 10 and the outer core 9 can be easily separated without degrading the performance of the electric motor 1.

[0037] According to at least one embodiment described above, the inner core 10 and the outer core 9 are separably engaged with each other by the engaging portion, thereby providing the rotor core 6, the rotor 3, and the electric motor 1 from which the magnets 7 incorporated in the electric motor 1 can be easily removed.

[0038] Although the present disclosure has been described in detail, the present disclosure is not limited to the individual embodiments described above. Various additions, substitutions, modifications, partial deletions, etc. are possible in these embodiments without departing from the gist of the present disclosure or the spirit of the present disclosure derived from the content of the claims and their equivalents. These embodiments can also be implemented in combination. For example, in the above-described embodiments, the order of each operation and the order of each process are shown as examples and are not limited to these. The same applies when numerical values ​​or mathematical expressions are used in the description of the above-described embodiments.

[0039] For example, the configuration of the insertion portion 13 may be the configuration of Modified Example 1 shown in Fig. 10, the configuration of Modified Example 2 shown in Fig. 11, the configuration of Modified Example 3 shown in Fig. 12, the configuration of Modified Example 4 shown in Fig. 13, or the configuration of Modified Example 5 shown in Fig. 14. Note that the inserted portion 14 has a shape corresponding to the shape of the insertion portion 13 so that the insertion portion 13 can be inserted.

[0040] In the case of the rotor core 6 of Modification 1 shown in Fig. 10, the insertion portion 13 has one piece 25 provided on the protruding portion 12 and a pair of other pieces 26, 26 provided on the one piece 25. The one piece 25 has a generally rectangular shape when viewed from the front, and protrudes inward from the tip of the protruding portion 12. The pair of other pieces 26, 26 are bifurcated from the tip of the one piece 25. The distance between the pair of other pieces 26, 26 increases as they move inward.

[0041] In the case of the rotor core 6 of Modification 2 shown in Fig. 11 , the insertion portion 13 has one piece 25 provided on the protruding portion 12 and another piece 26 provided on the one piece 25. The one piece 25 has a generally rectangular shape when viewed from the front, and protrudes inward from the tip of the protruding portion 12. The other piece 26 protrudes in a generally triangular shape from the tip of the one piece 25, tapering inward.

[0042] In the case of the rotor core 6 of Modification 3 shown in Figure 12, the insertion portion 13 has one piece 25 provided on the protruding portion 12 and another piece 26 provided on the one piece 25. The one piece 25 is generally rectangular in front view and protrudes inward from the tip of the protruding portion 12. The one piece 25 is biased toward one of the magnet slots 8. The other piece 26 protrudes in a generally triangular shape from the tip of the one piece 25 so as to taper inward. In this way, the insertion portion 13 is formed in a generally hook shape.

[0043] In the case of the rotor core 6 of the fourth modification shown in Fig. 13, the insertion portion 13 has one piece 25 provided on the protruding portion 12 and another piece 26 provided on the one piece 25. The one piece 25 has a generally rectangular shape when viewed from the front, and protrudes inward from the tip of the protruding portion 12. The other piece 26 protrudes in a generally trapezoidal shape from the tip of the one piece 25 so as to widen as it goes inward.

[0044] In the case of the rotor core 6 of modified example 5 shown in Figure 14, the insertion portion 13 has one piece 25 provided on the protruding portion 12 and another piece 26 provided on the one piece 25. The one piece 25 is generally rectangular in front view and protrudes inward from the tip of the protruding portion 12. The one piece 25 is biased toward one of the magnet slots 8. The other piece 26 protrudes from the tip of the one piece 25 toward the other magnet slot 8. In this way, the insertion portion 13 is formed in a generally hook shape.

[0045] The following supplementary notes are further disclosed regarding the above embodiment: (Supplementary Note 1) The rotor core (6) is a rotor core having magnet slots (8) into which magnets (7) are inserted, and includes a cylindrical outer core (9) that is not divided in the circumferential direction, an inner core (10) that is arranged inside the outer core (9) and has the magnet slots (8) between it and the outer core (9), and engaging portions (13, 14) that engage the outer core (9) and the inner core (10) in a separable manner so that the outer core (9) does not move relative to the inner core (10) in the circumferential and radial directions of the outer core (9), and the dividing surfaces of the outer core (9) and the inner core (10) are located inside the magnet slots (8).

[0046] (Supplementary Note 2) In Supplementary Note 1, the rotor core (6) may have a flux barrier (17) provided in a portion where the magnetic flux of the magnets (7) inserted in the magnet slots (8) does not pass and at a position in contact with the magnet slots (8).

[0047] (Supplementary Note 3) The rotor (3) includes the rotor core (6) according to Supplementary Note 1 or Supplementary Note 2, and the magnets (7) inserted into the magnet slots (8).

[0048] (Supplementary Note 4) In the rotor (3) of Supplementary Note 3, the rotor core (6) and the magnets (7) may be fixed together using a thermoplastic resin (20).

[0049] (Supplementary Note 5) The rotor (3) is a rotor including the rotor core (6) described in Supplementary Note 2 and the magnets (7) inserted into the magnet slots (8), wherein the rotor core (6) and the magnets (7) are fixed together using a thermoplastic resin (20), and the thermoplastic resin (20) is filled into the magnet slots (8) at both axial ends of the rotor core (6) so as to cover end faces (19) of the magnets (7), and may also be filled into the flux barriers (17).

[0050] (Supplementary Note 6) In the rotor (3) of any one of Supplementary Note 3 to Supplementary Note 5, the magnets (7) inserted into the magnet slots (8) may be neodymium magnets.

[0051] (Supplementary Note 7) The electric motor (1) comprises a rotor (3) as described in any one of Supplementary Notes 3 to 6, and a stator (2) disposed outside the rotor (3) so as to form a cylindrical gap (16) between the rotor (3) and the stator (2).

[0052] REFERENCE SIGNS LIST 1 electric motor 2 stator 3 rotor 6 rotor core 7 magnet 8 magnet slot 9 outer core 10 inner core 13 insertion portion 14 inserted portion 16 cylindrical gap 17 flux barrier 19 end face 20 thermoplastic resin

Claims

1. A rotor core having magnet slots into which magnets are inserted, comprising: a cylindrical outer core that is not divided in the circumferential direction; an inner core that is arranged inside the outer core and has the magnet slot between it and the outer core; and an engaging portion that engages the outer core and the inner core in a separable manner so that the outer core does not move circumferentially or radially relative to the inner core, wherein the dividing surface of the outer core and the dividing surface of the inner core are located inside the magnet slots.

2. A rotor core according to claim 1, further comprising a flux barrier provided in a portion of the magnet inserted in the magnet slot where the magnetic flux of the magnet does not pass and in a position in contact with the magnet slot.

3. A rotor comprising: the rotor core according to claim 1; and the magnets inserted into the magnet slots.

4. The rotor according to claim 3, wherein the rotor core and the magnets are fixed together using a thermoplastic resin.

5. A rotor comprising the rotor core according to claim 2 and the magnets inserted into the magnet slots, wherein the rotor core and the magnets are fixed together using a thermoplastic resin, and the thermoplastic resin is filled into the magnet slots at both axial ends of the rotor core so as to cover the end faces of the magnets, and is also filled into the flux barriers.

6. The rotor according to claim 3, wherein the magnets inserted into the magnet slots are neodymium magnets.

7. An electric motor comprising: a rotor according to claim 3; and a stator disposed outside the rotor so as to form a cylindrical gap between the rotor and a stator.

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