Permanent magnet rotating machine

Abstract

To provide a permanent magnet type rotary machine which has high rotational torque and can be made highly efficient, enables a surface magnet section thereof to be prevented from popping out in the centrifugal direction, is manufactured with high work efficiency, and in which sink marks, warpage, and voids of a bond magnet can be prevented.SOLUTION: The permanent magnet type rotary machine includes a shaft and a rotor mounted on the shaft and having a rotor core. The rotor is an electromagnetic steel sheet laminate with a roughly cylindrical outer periphery and has a through-hole axially penetrating the shaft. The permanent magnet type rotary machine has: a surface magnet portion of a bond magnet arranged in such a way as to surround all of the circumferential circumference of the rotor; and an internal magnet portion of the bond magnet disposed inside the rotor, connected to the surface magnet portion, and integral with the surface magnet portion.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a permanent magnet rotating machine. [Background technology]

[0002] In recent years, there has been an increasing trend in society towards higher efficiency, and the demand for highly efficient motors is also increasing in line with this trend.

[0003] In the case of motors, improvements have been made to improve rotational torque and achieve high efficiency without increasing the radial or axial dimensions, i.e., without increasing the size.

[0004] Patent Document 1 discloses a permanent magnet rotating machine equipped with a surface magnet section in which permanent magnets are arranged protruding from the surface of a rotor core so that adjacent magnets in the circumferential direction have different polarities. Furthermore, embedded magnet sections are provided in slots that run through the rotor core in the axial direction and correspond to the permanent magnets in the surface magnet section, with permanent magnets inserted in the slots so that they have the same polarity as the surface magnet sections.

[0005] This type of permanent magnet rotating machine has surface magnets and embedded magnets located inside the rotor core, so both the surface magnets and embedded magnets contribute to rotation, increasing the rotational torque. Furthermore, reluctance torque can be utilized in addition to the magnet torque, and this, combined with the magnet torque of the surface magnets, increases the rotational torque of the entire permanent magnet rotating machine, achieving high efficiency. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-279157 Summary of the Invention [Problem to be solved by the invention]

[0007] However, in the permanent magnet rotating machine of Patent Document 1, the surface magnet portion is fixed to the outer peripheral surface of the rotor core, and the surface magnet portion and the embedded magnet portion are not connected but are provided separately, so there was a risk that the surface magnet portion would fly out (scatter) in the centrifugal direction due to the centrifugal force caused by the rotation of the permanent magnet rotating machine.

[0008] Furthermore, in the permanent magnet rotating machine of Patent Document 1, the surface magnet portion and the embedded magnet portion are attached separately, which causes a problem of poor workability during manufacturing.

[0009] Meanwhile, this type of permanent magnet rotating machine typically uses bonded magnets, which are made with a resin material suitable for injection molding. While increasing the thickness of injection-molded bonded magnets improves rotational torque, once the thickness exceeds a certain level, sink marks, warpage, and voids occur during the molding process. Therefore, there is a limit to how much rotational torque can be improved simply by increasing the thickness of the bonded magnet.

[0010] The present invention has been made in consideration of the above, and aims to provide a permanent magnet rotating machine that has large rotational torque and is capable of achieving high efficiency, is able to prevent the surface magnet portion from protruding in the centrifugal direction, is easy to manufacture, and can prevent sink marks, warping, and voids in the bonded magnet. [Means for solving the problem]

[0011] In order to solve the above-mentioned problems and achieve the object, one aspect of the present invention provides a permanent magnet rotating machine including a shaft and a rotor having a rotor core attached to the shaft. The rotor core is an electromagnetic steel sheet laminate with a substantially cylindrical outer circumferential surface and has a through hole that penetrates in the axial direction of the shaft. The rotor core has a surface magnet portion of a bonded magnet arranged to surround the entire circumferential circumference of the rotor, and an internal magnet portion of a bonded magnet arranged inside the rotor, connected to the surface magnet portion, and integral with the surface magnet portion. The internal magnet portion has a generally arcuate shape that protrudes radially inward, and a non-filled portion, which is not filled with the bonded magnet, is provided in the central portion of the radially inner side.

[0012] A permanent magnet rotating machine according to one aspect of the present invention has a large rotational torque, enabling high efficiency, and is capable of preventing the surface magnet portion from protruding in the centrifugal direction, making manufacturing easier and preventing sink marks, warping, and voids in the bonded magnet. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is an external perspective view of a permanent magnet rotating machine according to one embodiment. [Figure 2] FIG. 2 is a ZZ cross-sectional view of the permanent magnet rotating machine of FIG. [Figure 3] FIG. 3 is a cross-sectional view showing only the rotor core among the components shown in FIG. [Figure 4] FIG. 4 is a diagram showing an example of magnetization of the surface magnet portion and the internal magnet portion. [Figure 5] FIG. 5 is a cross-sectional view (1) showing another example of the rotor. [Figure 6] FIG. 6 is a cross-sectional view (2) showing another example of the rotor. [Figure 7] FIG. 7 is a cross-sectional view (3) showing another example of the rotor. [Figure 8] FIG. 8 is a cross-sectional view of a permanent magnet rotating machine of a comparative example. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, a permanent magnet rotating machine according to an embodiment will be described with reference to the drawings. Note that the present invention is not limited to the embodiments. Furthermore, the dimensional relationships and ratios of elements in the drawings may differ from the actual situation. The dimensional relationships and ratios may differ between the drawings. Furthermore, the content described in one embodiment or modification also applies, in principle, to other embodiments or modifications.

[0015] Fig. 1 is an external perspective view of a permanent magnet rotating machine 1 according to one embodiment. Fig. 2 is a ZZ cross-sectional view of the permanent magnet rotating machine 1 of Fig. 1. Fig. 3 is a cross-sectional view showing only a rotor core 8 of the components of Fig. 2.

[0016] <Summary> In Fig. 1, a permanent magnet rotating machine 1 has a substantially cylindrical motor frame 2, one end of which is exposed from approximately the center of one of the bottom surfaces. In Fig. 2, a stator 4 is provided inside the motor frame 2, and is composed of a stator core 5 and coils 6 wound around teeth 5a of the stator core 5. A rotor 7 is provided inside the stator 4. The rotor 7 is composed of a rotor core 8, a surface magnet portion 9, and an internal magnet portion 10. The shaft 3 is attached to the rotor 7.

[0017] <Rotor core 8> In Fig. 3, a predetermined number of cores made of electromagnetic steel sheets pressed into a predetermined shape are stacked in the axial direction (Z-axis direction) and then caulked together to form rotor core 8, which is made of an electromagnetic steel sheet laminate. Through-holes 8f formed in the center of each core and rotor core 8 communicate (penetrate) over the entire axial length of rotor core 8. As shown in Fig. 2, shaft 3 is inserted into these through-holes 8f. The outer peripheral surface of shaft 3 is knurled (fleur-de-lis) to improve bonding strength and prevent rotation.

[0018] In Fig. 3, outer core portions 8a, connecting portions 8e, and inner core portions 8b are formed on the outer periphery of rotor core 8 by arc-shaped cutouts 8c and 8d. In other words, outer core portion 8a and inner core portion 8b are connected by connecting portion 8e, and the core can be molded as a single plate. In Fig. 2, surface magnet portions 9 are formed on the outer periphery of rotor core 8, and internal magnet portions 10 are formed in cutouts 8c and 8d.

[0019] <Surface magnet part 9> In Figure 2, the surface magnet portion 9 covers the entire circumference of the rotor 7, from one axial end to the other. The radial thickness of the surface magnet portion 9 is preferably 3 mm or less. The surface magnet portion 9 is connected to multiple internal magnet portions 10 on its radially inner side. The connected portions are called connecting portions 11.

[0020] The rotor 7 is manufactured by a common injection molding method in which a rotor core 8 made of electromagnetic steel sheet is inserted into the cavity of an injection mold, and a molten bonded magnet is injected into the injection mold. When an anisotropic bonded magnet is used, an orienting magnet is provided on the outer periphery of the cavity of the injection mold.

[0021] <Internal magnet part 10> 2, multiple internal magnet portions 10 are configured in a roughly arc shape, protrude radially inward, and are arranged side by side at regular intervals in the circumferential direction. The radially outer ends of the internal magnet portions 10 are connected to the surface magnet portions 9 by connecting portions 11.

[0022] In addition, radially inside the internal magnet portion 10, there is an unfilled portion 12 (corresponding to the connecting portion 8e of the rotor core 8) where no bond magnet is filled, and this unfilled portion 12 connects the outer core portion 8a and the inner core portion 8b.

[0023] <Bonded magnet> In Figure 2, the surface magnet portion 9 and the internal magnet portion 10 are formed by integral injection molding of a bonded magnet. In this case, the injection molding gate positions are preferably located at the connecting portions 11 between the surface magnet portion 9 and the internal magnet portion 10 to allow for easier resin flow (in the example shown, there are a total of 16 gate positions). Alternatively, it is also possible to set gate positions at the midpoints between adjacent connecting portions 11. In this case, the number of gates can be reduced, resulting in cost savings associated with the disposal of residual bonded magnets.

[0024] Here, the bonded magnet is made of a resin material containing rare earth magnet powder. The rare earth magnets include SmCo5 magnets, Sm2Co 17Magnets, rare earth iron-based magnets (NdFeB-based magnets and SmFeN-based magnets), and ferrite-based magnets such as barium ferrite (BaO·6Fe2O3) and strontium ferrite (SrO·6Fe2O3) are used.

[0025] Furthermore, if the bonded magnet is anisotropic, after the surface magnet portions 9 and internal magnet portions 10, which are permanent magnets, are formed, the compact is removed from the mold and demagnetized in advance to remove irregular magnetization. The demagnetized compact is then set in a magnetizing yoke (not shown) around which a magnetizing coil is wound, and a pulse current is applied to the magnetizing coil to magnetize the compact in a predetermined direction from the outer periphery of rotor core 8.

[0026] FIG. 4 is a diagram showing an example of the magnetization of the surface magnet portion 9 and the internal magnet portion 10. In FIG. 4, the magnetizing coils are arranged at both ends of the circumferential direction of the internal magnet portion 10, which protrudes radially inward, with the surface magnet portion 9 and the internal magnet portion 10 magnetized to north or south poles along the path of the magnetic flux generated by the magnetizing coil. That is, the outside of the surface magnet portion 9 is magnetized with alternating north and south poles as the internal magnet portion 10 protrudes radially inward, and the inside of the surface magnet portion 9 is magnetized with the opposite polarity. Similarly, the outside of the internal magnet portion 10 (the outer core portion 8a side) is magnetized with the opposite polarity to the inside of the surface magnet portion 9, and the inside of the internal magnet portion 10 (the inner core portion 8b side) is magnetized with the opposite polarity. Note that in this embodiment, the magnetizing coil is configured so that current flows from the back to the front of the drawing in the magnetizing coil, and the return current flows in the opposite direction.

[0027] <Flux Barrier> The rotor core 8 may be provided with a flux barrier in the form of a hole penetrating in the axial direction. Fig. 5 is a cross-sectional view showing another example of the rotor 7, in which a flux barrier 13 is provided in the outer core portion 8a. Fig. 6 is a cross-sectional view showing another example of the rotor 7, in which a flux barrier 13 is provided in the inner core portion 8b. Fig. 7 is a cross-sectional view showing another example of the rotor 7, in which a flux barrier 13 is provided in both the outer core portion 8a and the inner core portion 8b.

[0028] In this case, whether the flux barrier 13 is provided in the outer core portion 8a, the inner core portion 8b, or both, it is preferable to place the flux barrier 13 adjacent to the non-filled portion 12. Because the non-filled portion 12 is a location where magnetic flux leakage is likely to occur, having the flux barrier 13 adjacent to this portion increases the magnetic resistance of the path of leakage magnetic flux, thereby preventing magnetic flux leakage. In the illustrated example, the shape of the flux barrier 13 is round, but this is not intended to be limited to a round shape, and other shapes (e.g., elliptical, rectangular, triangular, star-shaped) are also acceptable.

[0029] <Comparative Example> FIG. 8 is a cross-sectional view of a comparative example of a permanent magnet rotating machine 1'. In FIG. 8, the permanent magnet rotating machine 1' includes a surface magnet section 13' in which permanent magnets 21' are protruding from the surface of a rotor core 12' so that adjacent magnets in the circumferential direction have different polarities. The permanent magnet rotating machine 1' also includes embedded magnet sections 14' in which permanent magnets 32' are inserted into slots 31' axially penetrating the rotor core 12' corresponding to the permanent magnets in the surface magnet section 13' so that the permanent magnets have the same polarity as the surface magnet section 13'. Note that reference numeral 2' denotes a cylindrical frame, 3' denotes a stator, 4' denotes a rotor, 5' denotes a rotating shaft, 6' denotes a slot, 7' denotes a magnetic pole tooth, and 8' denotes an excitation coil. Reference numeral G denotes a gap. S and N denote the polarities of the magnets.

[0030] In Figure 8, the surface magnet portion 13' is fixed to the outer peripheral surface of the rotor core 12', and the surface magnet portion 13' and the embedded magnet portion 14' are not connected but are provided separately, so there was a risk that the surface magnet portion 13' would fly out (scatter) in the centrifugal direction due to the centrifugal force caused by the rotation of the permanent magnet type rotating machine 1'.

[0031] In this regard, in the permanent magnet type rotating machine 1 in the embodiment of Figures 1 to 7, the surface magnet portion 9 and the internal magnet portion 10 are constructed from a bonded magnet that is integrally injection molded, so there is no risk of the surface magnet portion 9 flying out (scattering) in the centrifugal direction due to the centrifugal force caused by the rotation of the permanent magnet type rotating machine 1.

[0032] Furthermore, in FIG. 8, the surface magnet portion 13' and the embedded magnet portion 14' are attached separately, which causes a problem of poor workability during manufacturing.

[0033] In this regard, in the permanent magnet type rotating machine 1 in the embodiment of Figures 1 to 7, the surface magnet portion 9 and the internal magnet portion 10 are formed integrally, so the problem of poor workability during manufacturing is eliminated.

[0034] In addition, in FIG. 8, the permanent magnet type rotating machine 1' has, in addition to the surface magnet portion 13', an embedded magnet portion 14' provided inside the rotor core 12', so that both the surface magnet portion 13' and the embedded magnet portion 14' contribute to rotation, thereby increasing the rotational torque.

[0035] 1 to 7, both the surface magnet section 9 and the internal magnet section 10 contribute to rotation, so the effect of increasing rotational torque can be maintained. Therefore, even when the surface magnet section 9 and the internal magnet section 10 are configured with bonded magnets, it is possible to improve rotational torque without increasing thickness, and it is possible to prevent sink marks, warpage, and voids that occur when the thickness is increased.

[0036] Furthermore, in FIG. 8, the permanent magnet rotating machine 1′ can utilize reluctance torque in addition to magnet torque, which, combined with the magnet torque of the surface magnet portion 13′, increases the rotational torque of the entire permanent magnet rotating machine, thereby achieving high efficiency.

[0037] In this regard, the permanent magnet rotating machine 1 in the embodiment of Figures 1 to 7 also has an internal magnet section 10 provided inside the stator core 5 in addition to the internal magnet section 10, so it can utilize reluctance torque in addition to magnet torque. Therefore, in combination with the magnet torque of the surface magnet section 9, the rotational torque of the entire permanent magnet rotating machine 1 can be increased, making it possible to achieve high efficiency.

[0038] Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications are possible without departing from the spirit of the present invention.

[0039] As described above, the permanent magnet rotating machine according to the embodiment includes a shaft and a rotor having a rotor core attached to the shaft, the rotor core being a laminate of electromagnetic steel sheets with a substantially cylindrical outer periphery, with a through hole penetrating in the axial direction of the shaft, and having a surface magnet portion of bonded magnets arranged to surround the entire circumferential circumference of the rotor, and an internal magnet portion of bonded magnets arranged inside the rotor, connected to and integral with the surface magnet portion. This enables high rotational torque and high efficiency, prevents the surface magnet portion from protruding in the centrifugal direction, improves manufacturing workability, and prevents sink marks, warpage, and voids in the bonded magnets.

[0040] In other words, since the surface magnet portion and the internal magnet portion are connected, when the centrifugal force caused by the rotation of the rotating machine is applied to the surface magnet portion, the internal magnet portion serves to suppress centrifugal displacement of the surface magnet portion, thereby preventing the surface magnet portion from jumping out in the centrifugal direction.

[0041] Furthermore, since the surface magnet portion and the internal magnet portion are connected and molded by injection molding or the like, it is possible to mold both at the same time by injection molding or the like, which does not impair workability during manufacturing.

[0042] In addition, since the magnet has both a surface magnet portion and an internal magnet portion molded by injection molding or the like, and both the surface magnet portion and the internal magnet portion contribute to rotation, the rotational torque can be improved without increasing the thickness of either the surface magnet portion or the internal magnet portion, and sink marks, warping, and voids that occur when the thickness is increased can be prevented.

[0043] In addition to the surface magnet section, an internal magnet section is provided inside the rotor core, so that reluctance torque can be utilized in addition to magnet torque, and combined with the magnet torque of the surface magnet section, the rotational torque of the entire rotating machine can be increased, making it possible to achieve high efficiency.

[0044] The surface magnet portion and the internal magnet portion are simultaneously molded by injection molding, thereby realizing the manufacturing of the surface magnet portion and the internal magnet portion.

[0045] The internal magnet section has a generally arcuate shape that protrudes radially inward, and a non-filled section in the center of the inner radial section where the bonded magnet is not filled is provided, which allows for an integrated rotor core construction.

[0046] The rotor is also provided with multiple flux barriers that penetrate in the axial direction, and the flux barriers are provided adjacent to the non-filled portions, which increases the magnetic resistance of the leakage flux path around the non-filled portions, prevents magnetic flux leakage, prevents a decrease in rotational torque, and achieves high efficiency.

[0047] Furthermore, the present invention is not limited to the above-described embodiments. Configurations in which the above-described components are appropriately combined are also included in the present invention. Furthermore, further effects and modifications can be easily derived by those skilled in the art. Therefore, the broader aspects of the present invention are not limited to the above-described embodiments, and various modifications are possible. [Explanation of symbols]

[0048] 1 permanent magnet type rotating machine, 2 motor frame, 3 shaft, 4 stator, 5 stator core, 5a teeth, 6 coil, 7 rotor, 8 rotor core, 8a outer core portion, 8b inner core portion, 8c, 8d cutout portion, 8e connecting portion, 8f through hole, 9 surface magnet portion, 10 internal magnet portion, 11 connecting portion, 12 non-filled portion, 13 flux barrier

Claims

1. a shaft; and a rotor having a rotor core attached to the shaft, the rotor core is an electromagnetic steel sheet laminate having a substantially cylindrical outer circumferential surface, and has a through hole penetrating in the axial direction of the shaft; a surface magnet portion of a bonded magnet arranged to surround the entire circumference of the rotor; an internal magnet portion of a bonded magnet disposed inside the rotor, connected to the surface magnet portion, and integral with the surface magnet portion; The internal magnet portion has a generally arcuate shape that protrudes radially inward, A non-filled portion, which is a portion where the bonded magnet is not filled, is provided in the radially inner central portion. Permanent magnet rotating machine.

2. The surface magnet portion and the internal magnet portion are simultaneously molded by injection molding.

2. The permanent magnet rotating machine according to claim 1.

3. The rotor is provided with a plurality of flux barriers that penetrate the rotor in the axial direction, The flux barrier is provided adjacent to the non-filled portion.

3. The permanent magnet type rotating machine according to claim 1 or 2.

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