Rotor and motor

Abstract

To improve the characteristics of a motor.SOLUTION: A rotor includes a rotor core, a magnet, and a cover. The rotor core includes an annulus and a plurality of pole pieces. The magnet is arranged between two circumferentially adjacent magnetic pole pieces among the plurality of magnetic pole pieces. The two adjacent pole pieces have radially recessed recesses. The cover covers at least a part of the outer circumference of the magnet.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a rotor and a motor. [Background technology]

[0002] Inner rotor motors, known as IPM rotors, have plate magnets magnetized on both sides of the rotor, arranged in a radial spoke pattern so that adjacent plate magnets repel each other. IPM rotors sometimes use a locking structure to prevent the plate magnets from flying outward in the radial direction due to the repulsive force between adjacent plate magnets or the centrifugal force generated when the rotor rotates. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2018 / 043288 [Patent Document 2] Japanese Patent Application Laid-Open No. 2012-200053 Summary of the Invention [Problem to be solved by the invention]

[0004] However, leakage flux from the plate-shaped magnet occurs through the locking structure, which reduces the magnetic flux linking from the plate-shaped magnet to the stator coil, and this can result in a deterioration of motor characteristics.

[0005] In one aspect, an object is to provide a rotor and a motor that can improve motor characteristics. [Means for solving the problem]

[0006] In one aspect, the rotor comprises a rotor core, a shaft, a magnet, and a cover. , complex Number of pole pieces and an annular portion inward of the plurality of pole pieces;The magnet is disposed between two circumferentially adjacent pole pieces among the plurality of pole pieces. The cover has a flat portion and The aforementioned an inner peripheral portion protruding in the axial direction from the flat portion; The aforementioned Protruding from the flat surface in the axial direction , as the outer periphery Protrusion and 、 The size of the inner periphery of the annular portion is larger than the size of the inner periphery of the cover in the radial direction. The protruding portion of the cover covers the outer periphery of a portion of the magnet in the radial direction. The inner periphery of the cover is disposed between the annular portion and the shaft in the radial direction. The cover is formed of a non-magnetic material or a metal material with lower magnetic properties than the material forming the pole pieces.

[0007] According to one aspect, the motor characteristics can be improved. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a perspective view showing an example of a motor according to a first embodiment. [Figure 2] FIG. 2 is a cross-sectional view showing an example of the motor according to the first embodiment. [Figure 3] FIG. 3 is a cross-sectional view showing an example of a rotor core according to the first embodiment. [Figure 4] FIG. 4 is a perspective view showing an example of a rotor core according to the first embodiment. [Figure 5] FIG. 5 is an enlarged cross-sectional view showing an example of a recess of the rotor core in the first embodiment. [Figure 6] FIG. 6 is a cross-sectional view showing an example of a rotor according to the first embodiment. [Figure 7] FIG. 7 is a perspective view showing an example of a cover in the first embodiment. [Figure 8] FIG. 8 is a cross-sectional perspective view showing an example of a cover in the first embodiment. [Figure 9] FIG. 9 is a cross-sectional view showing an example of a rotor core according to the first embodiment. [Figure 10]FIG. 10 is a side cross-sectional view showing an example of the rotor core according to the first embodiment. [Figure 11] FIG. 11 is an enlarged cross-sectional view showing an example of a rotor according to the first embodiment. [Figure 12] FIG. 12 is a perspective view showing an example of a rotor according to the second embodiment. [Figure 13] FIG. 13 is a cross-sectional view showing an example of a rotor core according to the second embodiment. [Figure 14] FIG. 14 is a cross-sectional view showing an example of a rotor according to the second embodiment. [Figure 15] FIG. 15 is a perspective view showing an example of a cover in the second embodiment. [Figure 16] FIG. 16 is a cross-sectional perspective view showing an example of a cover in the second embodiment. [Figure 17] FIG. 17 is a side cross-sectional view showing an example of a rotor according to the second embodiment. [Figure 18] FIG. 18 is a side cross-sectional view showing an example of a rotor in the first modified example. [Figure 19] FIG. 19 is an enlarged cross-sectional view showing an example of a rotor in the second modified example. [Figure 20] FIG. 20 is a cross-sectional view showing an example of a rotor core in the third modified example. [Figure 21] FIG. 21 is a cross-sectional view showing an example of a rotor in the fourth modified example. DETAILED DESCRIPTION OF THE INVENTION

[0009] Below, an embodiment of the rotor disclosed in the present application will be described in detail with reference to the drawings. Note that the dimensional relationships and ratios of elements in the drawings may differ from reality. The drawings may also include portions where the dimensional relationships and ratios differ. To make the explanation easier to understand, each drawing may illustrate a coordinate system that includes at least one of the axial direction (the direction of the rotational axis of the motor 1), radial direction, and circumferential direction of the motor 1, which will be described later. In the following, the direction of the rotational axis of the motor 1 may be simply referred to as the "axial direction."

[0010] (First embodiment) First, a motor 1 according to the present embodiment will be described with reference to FIGS. 1 and 2. FIG. 1 is a perspective view showing an example of a motor according to the first embodiment. However, the stator is omitted from FIG. 1. FIG. 2 is a cross-sectional view showing an example of a motor according to the first embodiment. FIG. 2 shows a cross-section taken along line AA in FIG. 1. As shown in FIG. 1, the motor 1 according to the present embodiment includes a rotor 2 and a stator 80. The motor 1 described in each embodiment is an inner rotor type brushless motor. The motor 1 according to each embodiment is housed in a frame (not shown), for example.

[0011] The stator 80 is formed by punching out flat plate-like members made of a magnetic material such as a magnetic steel plate into the shape shown in FIG. 2 and stacking a plurality of such members in the axial direction. As shown in FIG. 2, the stator 80 includes a yoke 81, teeth 82, coils 83, and insulators 84. The yoke 81 is an annular member formed on the outer periphery of the stator 80. The teeth 82 protrude radially inward from the yoke 81. The coils 83 are wound around the teeth 82, for example, via the insulators 84.

[0012] 1 and 2, the rotor 2 is rotatably inserted into the radially inner side of the stator 80. The rotor 2 includes a rotor core 10, covers 20 and 30, a plurality of plate-shaped magnets 40, and a shaft 90. The shaft 90 is inserted into the radially inner side of the rotor 2, for example.

[0013] The rotor core 10 has a laminated structure obtained by stacking multiple steel plate cores made of a soft magnetic material such as silicon steel plate. FIG. 3 is a cross-sectional view showing an example of a rotor core according to the first embodiment. FIG. 4 is a perspective view showing an example of a rotor core according to the first embodiment. FIG. 3 shows a cross-section taken along line AA in FIG. 4. As shown in FIGS. 3 and 4, the rotor core 10 includes multiple pole pieces 11, connecting portions 12, support portions 15, and an annular portion 19. Note that the rotor core 10 may further include lightening portions 16, 17, and 18 to reduce leakage magnetic flux. Note that, hereinafter, when each pole piece 11 is to be distinguished, they may be referred to as pole pieces 11A to 11J.

[0014] The multiple pole pieces 11 extend radially outward from the annular portion 19. The multiple pole pieces 11 are arranged side by side in the circumferential direction. Each pole piece 11 has end portions 11p and 11q extending substantially radially and an outer peripheral portion 11r extending in the circumferential direction. The end portion 11p faces the end portion 11q of the circumferentially adjacent pole piece 11 across a gap 14. The outer peripheral portion 11r forms the outer periphery of the rotor 2.

[0015] As shown in FIGS. 3 and 5, one side of each outer peripheral portion 11r in the circumferential direction is provided with a recess 1a that is cut out in the circumferential and radial directions. Furthermore, the other side of each outer peripheral portion 11r in the circumferential direction is provided with a recess 1b that is cut out in the circumferential and radial directions. FIG. 5 is an enlarged cross-sectional view showing an example of a recess of a rotor core in the first embodiment. FIG. 5 is an enlarged view of a portion indicated by frame F1 in FIG. 3. As shown in FIG. 5, the recess 1a includes a first portion 1c that connects with the outer peripheral portion 11r and a second portion 1e that forms the inner diameter side end of the recess 1a and connects to the end 11p. Similarly, the recess 1b includes a first portion 1d that connects with the outer peripheral portion 11r and a second portion 1f that forms the inner diameter side end of the recess 1b and connects to the end 11q. The outer peripheral portion 11r, the first portion 1c of the recess 1a, and the second portion 1e of the recess 1a are continuously formed. Similarly, the outer peripheral portion 11r, the first portion 1d of the recess 1b, and the second portion 1f of the recess 1b are formed continuously. In other words, the outer peripheral portion 11r, the second portion 1e of the recess 1a, and the second portion 1f of the recess 1b form the outer diameter side end portion of the rotor core 10.

[0016] As shown in Fig. 5, recess 1b formed in pole piece 11A faces recess 1a formed in pole piece 11J, which is adjacent to pole piece 11A in the circumferential direction. More specifically, first portion 1d of recess 1b in pole piece 11A faces first portion 1c of recess 1a in pole piece 11J in the circumferential direction. Also, as shown in Fig. 5, recess 1b is formed so that angle R formed between second portion 1f and end 11q is an acute angle. The same is true for recess 1a.

[0017] A shaft 90 is inserted into the radially inside of the annular portion 19 via inner peripheral portions 29 and 39 of the covers 20 and 30. The pole pieces 11 and the annular portion 19 are connected in the radial direction by connecting portions 12. In this embodiment, the inner diameter of the annular portion 19 is formed to be larger than the outer diameters of the inner peripheral portions 29 and 39 of the covers 20 and 30.

[0018] The support portion 15 extends radially outward from the annular portion 19. In other words, the support portion 15 protrudes radially outward from the annular portion 19. As shown in FIG. 3, the support portion 15 faces the gap 14 in the radial direction. In this embodiment, the width of the gap 14 is formed, for example, to be approximately the same as or slightly larger than the width (length in the circumferential direction) of the plate-shaped magnet 40. Furthermore, air layers 14a and 14b are formed on both circumferential sides of the radially inner side of the gap 14. Note that, at this time, the air layers 14a and 14b are arranged adjacent to each other in the circumferential direction of the support portion 15.

[0019] As shown in FIG. 6, the plate magnets 40 are inserted into the gaps 14 of the rotor core 10. FIG. 6 is a cross-sectional view showing an example of a rotor according to the first embodiment. FIG. 6 shows a cross-section of the rotor 2 taken along line AA in FIG. 4. The rotor 2 according to this embodiment includes ten plate magnets 40. In the following description, when the plate magnets 40 are to be distinguished from one another, they may be referred to as plate magnets 4a to 4j.

[0020] As shown in FIG. 6, the plate magnet 40 has a radially outer end face 41, a radially inner end face 42, a counterclockwise circumferential end face 43, and a clockwise circumferential end face 44. Also, as shown in FIG. 6, the plate magnet 40 has a north pole 4N and a south pole 4S. In this embodiment, two plate magnets 40 adjacent in the circumferential direction are arranged so that the same poles face each other. For example, as shown in FIG. 6, two plate magnets 4a and 4b adjacent in the circumferential direction are arranged so that their north poles 4N face each other. Also, two plate magnets 4j and 4a adjacent in the circumferential direction are arranged so that their south poles 4S face each other.

[0021] The radially inner end face 42 of the plate magnet 40 is supported in the radial direction by the support portion 15 of the rotor core 10. Specifically, the end face 42 is supported by the support portion 15 near the circumferential center of the plate magnet 40. In this embodiment, the support portion 15 supports the transition point of the plate magnet 40 where the north pole 4N and the south pole 4S switch. In this case, unlike conventional structures, the circumferential ends of the end face 42 do not have a locking structure. Instead, air layers 14a and 14b are provided, so the magnetic flux generated from both circumferential ends of the end face 42 is guided to the rotor core 10. In this case, the magnetic flux that flows directly into the different magnetic pole on the other side of the plate magnet without interlinking with the stator winding is reduced. This configuration suppresses magnetic flux leakage from both circumferential ends on the radially inner side of the plate magnet 40.

[0022] In the rotor 2 shown in FIG. 6, the plate magnets 40 arranged on the rotor core 10 may protrude radially outward or in the positive or negative axial direction due to repulsive forces between adjacent plate magnets 40 in the circumferential direction or centrifugal forces generated by rotation of the rotor 2. Therefore, in this embodiment, covers 20 and 30 as shown in FIGS. 7 and 8 are attached to the rotor core 10 as shown in FIG. 1 to prevent the plate magnets 40 from protruding. FIG. 7 is a perspective view showing an example of a cover in the first embodiment. FIG. 8 is a cross-sectional perspective view showing an example of a cover in the first embodiment. FIG. 8 shows a cross section taken along line CC in FIG. 7. As shown in FIG. 1, the cover 20 is attached to the rotor core 10 from the positive axial direction, and the cover 30 is attached to the rotor core 10 from the negative axial direction.

[0023] As shown in Fig. 7, cover 20 includes a plurality of protrusions 21, a flat portion 25, and an inner peripheral portion 29. Cover 20 may further include a plurality of openings 22. Note that although Fig. 7 illustrates cover 20 and Fig. 8 illustrates cover 30, covers 20 and 30 in this embodiment have the same shape, and the matters described below for cover 20 also apply to cover 30 unless otherwise specified. Similarly, the matters described below for cover 30 also apply to cover 20 unless otherwise specified.

[0024] In this embodiment, the cover 20 is made of a non-magnetic material such as brass. Alternatively, the cover 20 may be made by bending a material that has lower magnetic properties than the magnetic steel plate that constitutes the rotor core 10, such as austenitic stainless steel.

[0025] As shown in FIG. 7 , each protrusion 21 protrudes in the axial direction from the flat surface 25. The multiple protrusions 21 are, for example, arranged at equal intervals in the circumferential direction. More specifically, as shown in FIGS. 9 and 10 , the same number of protrusions 21 as the number of plate magnets 40 are formed at positions that contact a portion of the plate magnet 40, for example, a portion of the end face 41 on the positive axial direction side. FIG. 9 is a cross-sectional view showing an example of a rotor core according to the first embodiment. Note that the plate magnets are omitted in FIG. 9 . FIG. 10 is a side cross-sectional view showing an example of a rotor core according to the first embodiment. FIG. 10 shows a cross section taken along line BB in FIGS. 1 and 9 . FIG. 9 shows a cross section taken along line DD in FIG. 1 or 10 . As shown in FIG. 10 , the plate magnet 40 further includes an end face 45 on the positive axial direction side and an end face 46 on the negative axial direction side in addition to the end faces 41 to 44 shown in FIGS. 6 and 9 .

[0026] 9 and 10 , each protrusion 21 of cover 20 protrudes toward the negative axial direction, and each protrusion 31 of cover 30 protrudes toward the positive axial direction. In this case, of the radially outer end face 41 of plate-shaped magnet 40, a portion on the positive axial direction side contacts protrusion 21 of cover 20, and a portion on the negative axial direction side contacts protrusion 31 of cover 30.

[0027] Opening 22 is formed to penetrate flat portion 25 in the axial direction. As shown in Fig. 10, opening 22 faces end face 45 of plate-shaped magnet 40 on the positive axial side. In this case, as shown in Fig. 1, plate-shaped magnet 40 can be seen from the positive axial side through opening 22.

[0028] The inner circumferential portion 29 protrudes in the axial direction from the flat portion 25, similar to the protruding portion 21. The outer diameter of the inner circumferential portion 29 is, for example, substantially the same as or slightly larger than the inner diameter of the annular portion 19 of the rotor core 10. The inner diameter of the inner circumferential portion 29 is, for example, substantially the same as or slightly smaller than the outer diameter of the shaft 90. In this configuration, the covers 20 and 30 are inserted, for example, by being press-fitted between the annular portion 19 of the rotor core 10 and the shaft 90 in the radial direction. By connecting the shaft 90 to the rotor core 10 via the inner circumferential portion 29, the force applied when assembling the shaft 90 and the rotor core 10 is not large, even if the axial length of the rotor core 10 is long. This allows the connecting force between the shaft 90 and the rotor core 10 to be constant regardless of the axial length of the rotor core 10. At this time, the bonding force between the rotor core 10 and the cover 20 can be adjusted by changing the shape, such as by making the inner diameter of the annular portion 19 of the rotor core 10 or the outer diameter of the inner peripheral portion 29 of the cover 20 polygonal, thereby adjusting the bonding force between the shaft 90 and the rotor core 10.

[0029] FIG. 11 is an enlarged cross-sectional view showing an example of a rotor according to the first embodiment. FIG. 11 is an enlarged view of the portion indicated by frame F2 in FIG. 9. As shown in FIG. 11, the radially outer end surface 41 of the plate magnet 40, which contacts the protruding portion 31 of the cover 30, protrudes radially outward beyond the recesses 1a and 1b, more specifically, the second portion 1e of the recess 1a and the second portion 1f of the recess 1b. In this configuration, a radial gap Ga is formed between the protruding portion 31 and the second portion 1e of the recess 1a of the rotor core 10. Similarly, a radial gap Gb is formed between the protruding portion 31 and the second portion 1f of the recess 1b. Furthermore, a radial gap Gx is formed between the corners 1g and 1h and the cover 20. In this embodiment, the corners 1g and 1h form acute angles (angle R shown in FIG. 5).

[0030] In this configuration, the radially outer end surface 41 of the plate-shaped magnet 40 does not have a locking structure for the rotor core 10 in the radial direction, as shown in FIG. 6 . Therefore, magnetic flux generated from the circumferential end is guided to the rotor core 10. Because the covers 20 and 30 are made of a nonmagnetic material or a material with lower magnetic properties than the magnetic steel plate constituting the rotor core 10, leakage of magnetic flux that would otherwise flow directly to the opposite magnetic pole on the other side of the plate-shaped magnet is suppressed. Furthermore, the recesses 1a and 1b facilitate the placement of the covers 20 and 30 and increase the length of the magnetic path of leakage magnetic flux, thereby increasing magnetic resistance and suppressing leakage magnetic flux. Furthermore, by making the corners 1g and 1h acute angles, the magnetic path of leakage magnetic flux connecting from the recesses 1a and 1b to the other recess also exits the air layer almost perpendicularly from the recesses 1a and 1b. This further increases the distance to the other recess, increasing magnetic resistance and further suppressing magnetic flux leakage.

[0031] Furthermore, in an IPM rotor, it is difficult to achieve a sinusoidal magnetic flux density distribution across the rotor surface, which is an ideal waveform for preventing cogging and torque ripple. Therefore, as shown in Patent Document 1, the curvature of the pole piece tips is adjusted to improve cogging and torque ripple. However, when a locking structure is required on the radially outer side of the plate-shaped magnet, there are limitations on the shape of the pole piece tips that can be selected. However, in this embodiment, each pole piece 11 does not require a locking structure to be installed on the rotor core. The plate-shaped magnet 40 protrudes radially outward from the recesses 1a and 1b of the rotor core 10, but is positioned radially inward from the outer periphery 11r. With this configuration, cogging and torque ripple can be easily adjusted by changing the width and curvature of the outer periphery 11r.

[0032] As described above, the rotor 2 in this embodiment includes the rotor core 10, the magnet 40, and the covers 20 and 30. The rotor core 10 has a plurality of magnetic pole pieces 11 and an annular portion 19. The magnet 40 is disposed between two circumferentially adjacent magnetic pole pieces of the plurality of magnetic pole pieces 11. The covers 20 and 30 cover the outer periphery of the magnet 40 and are formed of a non-magnetic material or a material with lower magnetic properties than the rotor core 10. This configuration can suppress leakage of magnetic flux through the rotor core 10, thereby improving motor characteristics.

[0033] In this embodiment, two adjacent pole pieces 11 have recesses 1a, 1b recessed in the radial direction, and the recesses 1a, 1b of the two adjacent pole pieces 11 are arranged to face the magnet 40 in the circumferential direction. Furthermore, gaps Ga, Gb are formed in the radial direction between the inner diameter side ends 1e, 1f of the recesses 1a, 1b and the covers 20, 30. This configuration makes it possible to prevent magnetic flux from leaking radially outward.

[0034] Furthermore, in this embodiment, the covers 20 and 30 are formed of a non-magnetic material or a material with lower magnetic properties than the material forming the pole pieces 11 of the rotor core 10. In this embodiment, at least a portion of the radially outer end face 41 of the plate-shaped magnet 40 contacts the non-magnetic or low-magnetic covers 20 and 30. Because the radially outer end face 41 of the plate-shaped magnet 40 does not have a locking structure in the radial direction that is provided by the rotor core 10, magnetic flux that does not interlink with the stator winding and flows directly into the different magnetic pole on the other side of the plate-shaped magnet is suppressed. This configuration reduces leakage magnetic flux.

[0035] Furthermore, the cover 20 in this embodiment may have an opening 22 that opens in the axial direction. In this case, the opening 22 faces the magnet 40 in the axial direction. In this case, by injecting an adhesive or the like through the opening 22, the plate-shaped magnet 40 and the rotor core 10 can be easily fixed together.

[0036] (Second embodiment) The covers 20 and 30 in the first embodiment can be easily formed by bending a metal plate or the like, so it is easy to form covers with shapes different from those shown in the first embodiment. For example, the cover may be formed so as to contact not only a portion of the end face 41 of the plate-shaped magnet 40 but also a portion of the end face 42. FIG. 12 is a perspective view showing an example of a rotor in the second embodiment. As shown in FIG. 12, the motor A1 in the second embodiment includes a rotor A2 and a stator 80. However, the stator is omitted in FIG. 12. In the following embodiments and modifications, parts that are the same as those shown in the drawings described above will be designated by the same reference numerals, and duplicated explanations will be omitted.

[0037] The rotor A2 shown in FIG. 12 includes a rotor core 50, covers 60 and 70, a plate magnet 40, and a shaft 90. As shown in FIG. 13, the rotor core 50 includes a plurality of pole pieces 51, a connecting portion 52, and an annular portion 59. FIG. 13 is a cross-sectional view showing an example of a rotor core according to a second embodiment. As shown in FIG. 13, the pole pieces 51 according to the second embodiment include an outer circumferential portion 11r extending in the circumferential direction and end portions 51p and 51q extending in the radial direction. In the second embodiment as well, the plurality of pole pieces 51 and the annular portion 59 are connected in the radial direction by the connecting portion 52. The pole pieces 51 may further include a lightening portion 58.

[0038] In the second embodiment, the plate magnet 40 is also housed in a gap 54 between two adjacent magnetic pole pieces 51 in a rotor core 50, as shown in Fig. 14. Fig. 14 is a cross-sectional view showing an example of a rotor in the second embodiment.

[0039] In the second embodiment, the ends 51p and 51q extend radially inward beyond the radially inner end face 42 of the plate-shaped magnet 40. In this configuration, the radially inner end face 42 of the plate-shaped magnet 40 in the second embodiment is supported by the cover 70, not by the support portion 15, as shown in FIG.

[0040] Fig. 15 is a perspective view showing an example of a cover in the second embodiment. Fig. 16 is a cross-sectional perspective view showing an example of a cover in the second embodiment. Fig. 16 shows a cross section taken along line CC in Fig. 15. Also, in the second embodiment, covers 60 and 70 have the same shape, and matters described below for cover 60 also apply to cover 70 unless otherwise specified. Similarly, matters described below for cover 70 also apply to cover 60 unless otherwise specified.

[0041] In the second embodiment, the cover 60 is also formed of a non-magnetic material such as brass, or a material with lower magnetic properties than the magnetic steel plates that form the rotor core 50. As shown in Fig. 15, the cover 60 further includes a contact portion 66 in addition to the protrusion 21, the opening 22, the flat portion 25, and the inner circumferential portion 29.

[0042] The contact portions 66 of the cover 60 protrude in the axial direction from the flat portion 25, similar to the protruding portions 21 and the inner peripheral portion 29. Similar to the protruding portions 21, the contact portions 66 are also formed, for example, at equal intervals in the circumferential direction so as to face the plate-shaped magnets 40 in the radial direction, and the number of the contact portions 66 is the same as the number of the plate-shaped magnets 40. Furthermore, similar to the openings 22, portions that axially penetrate the flat portion 25 are formed around the contact portions 66. In the second embodiment, the contact portions 66 of the cover 60 protrude in the negative axial direction, and the contact portions 76 of the cover 70 protrude in the positive axial direction.

[0043] As shown in FIGS. 14 and 17, the contact portions 66 and 76 contact the radially inner end surface 42 of the plate magnet 40. FIG. 17 is a side cross-sectional view showing an example of a rotor according to the second embodiment. As shown in FIGS. 14 and 17, the contact portion 66 is inserted into the gap 54 of the rotor core 50 from the positive axial direction side. The contact portion 66 supports the radially inner end surface 42 of the plate magnet 40 from the radially inner side. In this configuration, the plate magnet 40 is supported in the radial direction by the protrusion 21 and contact portion 66 of the cover 60, and the protrusion 31 and contact portion 76 of the cover 70.

[0044] As described above, in the rotor A2 of the second embodiment, the cover 60 has a contact portion 66, and the contact portion 66 contacts the magnet 40 at the radially inner end face 42 of the magnet 40. This configuration suppresses leakage of magnetic flux from one of the radially inner end faces of the plate-shaped magnet 40, which would otherwise flow directly to the different magnetic pole on the other face of the plate-shaped magnet without linking with the stator winding.

[0045] Although the configurations of the respective embodiments have been described above, the embodiments are not limited thereto. For example, the axial end faces 45 and 46 of the plate magnet 40 do not have to be flush with the axial end faces of the rotor core 10. As shown in FIG. 18 , the axial end face 45 of the plate magnet 40 may protrude further in the positive axial direction than the axial end face of the rotor core B0. FIG. 18 is a side cross-sectional view showing an example of a rotor according to a first modified example. In the configuration shown in FIG. 18 , the axial length of the rotor core B0 is shorter than the length of the plate magnet 40. Specifically, a space C is formed between the rotor core B0 and the covers 20 and 30 in the axial direction. As a result, the axial end faces 45 and 46 of the plate magnet 40 do not face the support portion B5 of the rotor core B0 in the radial direction. Furthermore, the inner circumferential portion 29 of the cover 20 and the inner circumferential portion 39 of the cover 30 are disposed between the end faces 45 and 46 and the shaft 90, which faces the plate magnet 40 in the radial direction.

[0046] With this configuration, the magnetic flux of the plate magnet 40 can be concentrated in the area facing the stator, and the magnetic flux interlinking with the stator windings can be increased, thereby improving the characteristics of the motor.

[0047] In the first embodiment, the protrusion 21 of the plate-shaped magnet 40 has the entire axial end of the radially outer end face 41 in contact with the protrusion in the circumferential direction, as shown in FIG. 6, and the recesses 1a and 1b are in contact with the apex of the protrusion 21, but the embodiment is not limited to this. For example, as shown in FIG. 19, the rotor C0 may be configured so that only a portion of the plate-shaped magnet 40 in the circumferential direction, more specifically, only the vicinity of the central portion in the circumferential direction, is in contact with the protrusion C31. FIG. 19 is an enlarged cross-sectional view showing an example of a rotor in a second modified example. In this configuration, the protrusion C31 of the cover C30 does not contact the recesses 1a and 1b. As long as the configuration can prevent the plate-shaped magnet 40 from protruding, the protrusion 21c may be configured to cover only the central portion of the plate-shaped magnet 40, as shown in FIG. 19.

[0048] 5, the outer circumferential portion 11r, the first portion 1c, the second portion 1e, and the end portion 11p are continuously connected by, for example, a curved line, but this is not limited thereto and they may be formed discontinuously by a straight line. The same applies to the outer circumferential portion 11r, the first portion 1d, the second portion 1f, and the end portion 11q. The end portions 11p and 11q of the rotor core 10 may be formed in a curved line. In this case, for example, the first portions 1c and 1d may be in contact with the entire end face in the circumferential direction of the protrusion 21 of the cover 20.

[0049] Furthermore, in the rotor core 50 of the second embodiment, no circumferentially extending air layer corresponding to 14a and 14b in FIG. 3 is formed radially inside the gap 54. However, this is not limited thereto. As shown in FIG. 20, an annular portion D9 and a support portion D5 protruding radially outward from the annular portion D9 may be provided, thereby providing air layers D4a and D4b extending circumferentially in the gap D4. In other words, the support portion D5 and the air layers D4a and D4b are arranged adjacent to each other in the circumferential direction. FIG. 20 is a cross-sectional view showing an example of a rotor core according to a third modified example. In the rotor core D0 of the third modified example, the multiple magnetic pole pieces D1 and the annular portion D9 are also connected radially by the connecting portion D2. This configuration can prevent magnetic flux from leaking from both circumferential ends of the plate magnets 40 radially inside.

[0050] Furthermore, in the rotor core 50 of the second embodiment, radially recessed recesses corresponding to 1a and 1b in FIG. 3 are formed at the outer peripheral end portion. However, this is not limited thereto. As shown in FIG. 21, the outer peripheral portion E1r and the ends E1p and E1q of the pole pieces E1 of the rotor core E0 may be formed continuously without any recesses. FIG. 21 is a cross-sectional view showing an example of a rotor according to a fourth modified example. In the rotor core E0 shown in FIG. 21, the outer peripheral portion E1r and the ends E1p and E1q are arranged continuously. This configuration makes it possible to easily manufacture a rotor core E50 with multiple poles or a small diameter.

[0051] As in the second modification, the protrusion C31 of the cover C30 in the fourth modification contacts only the vicinity of the circumferential center of the plate-shaped magnet 40. In this case, the radially inner end face 42 of the plate-shaped magnet 40 is supported by the contact portion C36 of the cover C30, but this is not limited thereto and the plate-shaped magnet 40 may be supported by the support portion D5 of the rotor core D0 as shown in Fig. 20. Furthermore, although the fourth modification does not have a configuration corresponding to the connecting portion 52 in Fig. 13, a lightening portion 58 and a connecting portion 52 may be provided as in Fig. 13.

[0052] Although the present invention has been described above based on the embodiments and modifications thereof, it goes without saying that the present invention is not limited to the embodiments and modifications thereof, and various modifications are possible without departing from the spirit of the present invention. Such modifications without departing from the spirit of the present invention are also included in the technical scope of the present invention, and this will be clear to those skilled in the art from the description of the claims. [Explanation of symbols]

[0053] 1, A1 motor, 2, A2 rotor, 10, 50, B0, D0, E0 rotor core, 11, 51, D1, E1 pole pieces, 12, 52, D2 connecting portion, 14, 54, D4 gap, 15, D5 support portion, 19, 59, D9 annular portion, 20, 30, 60, 70 cover, 21, 31, C31 protruding portion, 22, 32 opening, 25, 35 flat portion, 66, 76, C36 contact portion, 29, 39 inner peripheral portion, 40 plate-shaped magnet, 80 stator, 90 shaft, 1a, 1b recess, 11r, E1r outer peripheral portion, 11p, 11q, 51p, 51q, E1p, E1q end portion, 1c, 1d first portion, 1e, 1f 2nd part, 1g, 1h corner

Claims

1. A plurality of magnetic pole pieces; an annular portion inward of the plurality of pole pieces; a rotor core having A shaft and a magnet disposed between two circumferentially adjacent pole pieces among the plurality of pole pieces; a cover having a flat surface portion, an inner peripheral portion protruding in the axial direction from the flat surface portion, and a protruding portion as an outer peripheral portion protruding in the axial direction from the flat surface portion, In the radial direction, the size of an inner circumferential portion of the annular portion is larger than the size of an inner circumferential portion of the cover, the protruding portion of the cover covers a part of the outer periphery of the magnet in the radial direction, an inner circumferential portion of the cover is disposed between the annular portion and the shaft in a radial direction; The cover is formed of a non-magnetic material or a metal material having a lower magnetic property than the material forming the pole pieces. Rotor.

2. The ends of the outer peripheries of the two adjacent magnetic pole pieces on the magnet side have recesses recessed in the radial direction, The rotor according to claim 1 , wherein the protrusion of the cover faces the recess in the radial direction.

3. The rotor according to claim 2 , wherein the recesses of the two adjacent pole pieces face the magnets across a gap in the circumferential direction.

4. 4. The rotor according to claim 1, wherein the cover has an opening that opens in the axial direction, the opening facing the magnet in the axial direction.

5. The rotor core has a support portion that protrudes in a radial direction, The support portion and the magnet are in contact with each other. A rotor according to any one of claims 1 to 4.

6. the cover has a contact portion; The contact portion contacts the magnet on the radially inner side of the magnet. A rotor according to any one of claims 1 to 5.

7. A motor having a rotor according to any one of claims 1 to 6.

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