Rotor for rotating electric machine and rotating electric machine equipped with the same

Abstract

To reduce manufacturing cost of a rotor and a rotary electric machine by making it possible to assemble a magnet with a small number of working processes without requiring strict dimensional management of the magnet.SOLUTION: A rotor 4 includes a plurality of magnets 14 and a yoke 13 disposed radially inside the magnets 14. An arrangement of the magnets 14 is a Halbach array in which, between a pair of main magnets 31 including first main magnets 31A having a magnetic pole direction directed radially inward and second main magnets 31B having a magnetic pole direction directed radially outward, sub-magnets 33 having a magnetic pole direction including components directed toward the second main magnets 31B are disposed. One of the main magnet 31 and the sub-magnet 33 exhibits an outer tapered curved trapezoidal shape in which an outer circumferential width is shorter than an inner circumferential width, and the other exhibits an inner tapered curved trapezoidal shape in which the inner circumferential width is shorter than the outer circumferential width. The main magnet 31 and the sub-magnet 33 are held in a close contact state with each other by an annular holding member 35 made of a non-magnetic material disposed outside them.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a rotor for a rotating electric machine and a rotating electric machine including the rotor. [Background technology]

[0002] A surface-permanent magnet synchronous motor in which multiple permanent magnets (hereinafter simply referred to as magnets) are fixed to the surface of a rotor core is known (see Patent Document 1). In this motor, a fixing member is provided to hold the multiple magnets on the surface of the rotor core and secure the magnets in place. The fixing member is attached to the outer periphery of all the magnets in an interference fit relationship, closely surrounding the outer periphery of all the magnets. This prevents the magnets from scattering due to radial external forces such as magnetic attraction and centrifugal force.

[0003] Also known as a surface-permanent synchronous motor is one in which two types of divided magnets of different thicknesses are arranged alternately in the circumferential direction with no gaps between them (see Figure 14 of Patent Document 2). In this motor, the thinner divided magnets are arranged away from the rotor core, forming grooves (through holes between the rotor core and the divided magnets) on the inner circumferential surfaces of the annularly arranged magnets. Alternatively, multiple divided magnets are arranged so that grooves are formed on the outer circumferential surfaces of the annularly arranged magnets. This suppresses the temperature rise of the rotor. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 9-93844 [Patent Document 2] Japanese Patent Application Publication No. 8-205438 Summary of the Invention [Problem to be solved by the invention]

[0005] Incidentally, one type of magnet arrangement for rotors is the so-called Halbach array, in which a pair of main magnets whose magnetization directions face outward and inward in the radial direction of the rotor are sandwiched between sub-magnets whose magnetization direction includes a circumferential component of the rotor. When a large number of magnets are used in a single rotor, as in a rotor with a Halbach array, more precise anti-shatter measures must be taken for all magnets. For example, measures such as machining the magnet surface after attaching it to the outer periphery of the rotor core (yoke) and strictly controlling the dimensional tolerances of the thickness and width of all magnets were necessary. This increased the number of processing steps and the costs of dimensional control.

[0006] In view of the above background, an object of the present invention is to enable magnets to be assembled without strict dimensional control of the magnets and with fewer processing steps, thereby reducing the manufacturing costs of rotors and rotating electric machines. [Means for solving the problem]

[0007] In order to solve the above-mentioned problems, one aspect of the present invention is a rotor (4) of a rotating electric machine (1), comprising a plurality of magnets (14) arranged in a predetermined circumferential arrangement, and a yoke (13) arranged radially inward of the magnets, the predetermined arrangement being a Halbach arrangement in which a sub-magnet (33) having a magnetic pole direction including a component facing toward the second main magnet (31B) is arranged between a pair of main magnets (31) including a first main magnet (31A) having a magnetic pole direction facing radially inward and a second main magnet (31B) having a magnetic pole direction facing radially outward, one of the main magnet and the sub-magnet has an outer tapered curved trapezoidal shape with an outer circumferential width shorter than its inner circumferential width, and the other of the main magnet and the sub-magnet has an inner tapered curved trapezoidal shape with an inner circumferential width shorter than its outer circumferential width, and the main magnet and the sub-magnet are held in close contact with each other by an annular holding member (35) made of a non-magnetic material arranged outside them.

[0008] According to this aspect, the outer tapered magnet is held by the inner tapered magnet from the radially outer side while in close contact with the inner tapered magnet, and the inner tapered magnet is held by a retaining member from the radially outer side. This prevents these magnets from scattering due to radial external forces such as centrifugal force. Furthermore, because the outer tapered magnet is held by the inner tapered magnet from the radially outer side, these magnets can be assembled to the outer periphery of the yoke while in close contact with the circumferential direction without strict control of the magnet dimensions. This reduces the number of processing steps and the cost of dimensional control.

[0009] In the above aspect, the main magnet may have an inwardly tapered curved trapezoidal shape.

[0010] According to this aspect, it is possible to reduce the demagnetizing field regions that occur at the radially inner and outer corners of the contact portion where adjacent main magnets and sub-magnets come into contact, thereby reducing the demagnetization factor of the rotor, thereby improving the output reduction due to rotor demagnetization.

[0011] In the above aspect, it is preferable that the radial thickness of one of the main magnet and the sub-magnet is greater than the radial thickness of the other of the main magnet and the sub-magnet.

[0012] According to this aspect, a gap is formed between the main magnet or sub-magnet and the yoke, or between the main magnet or sub-magnet and the retaining member. This reduces the demagnetizing field area at the corners of the magnets near the gap, further improving output reduction due to rotor demagnetization.

[0013] In the above aspect, it is preferable that the radial thickness of the main magnet is greater than the radial thickness of the sub-magnet.

[0014] According to this aspect, by increasing the radial thickness of the main magnet, a gap is formed between the sub-magnet and the retaining member. This makes it possible to reduce the demagnetizing field area at the corners of the sub-magnet near the gap. As a result, output reduction due to demagnetization of the rotor is further improved.

[0015] In the above aspect, the inner circumferential width (X) of the main magnet is greater than the distance (A) between the inner surfaces of the sub-magnets arranged on both sides of the main magnet in the circumferential direction, and the outer circumferential width (Y) of the main magnet is greater than the distance (B) between the outer surfaces of the sub-magnets, and the main magnet abuts against the holding member and forms a gap between the yoke, and the sub-magnet abuts against the yoke and forms a gap between the holding member.

[0016] According to this aspect, by forming gaps between the main magnets and the yoke and between the sub-magnets and the retaining member, the area of ​​the magnet surfaces exposed to the atmosphere is increased, thereby suppressing a decrease in output due to heat generation from the rotor.

[0017] In addition, in order to solve the above problem, one aspect of the present invention is a rotating electric machine (1), which includes a rotor (4) of the above aspect, a stator (5) provided on the outside of the rotor, a rotating shaft (11) that is driven to rotate by the rotor, and a fan (22) provided on the rotating shaft that blows air toward the magnet when rotating.

[0018] According to this aspect, the magnet is cooled by the wind blown by the fan and by the wind passing through the gap, thereby reducing torque variations due to overheating of the magnet.

[0019] In order to solve the above-mentioned problems, one aspect of the present invention is a rotor (4) of a rotating electric machine (1), comprising a plurality of magnets (14) arranged in a predetermined circumferential arrangement, and a yoke (13) arranged radially inside the magnets, the predetermined arrangement including a pair of main magnets (31) including a first main magnet (31A) having a magnetic pole direction facing radially inward and a second main magnet (31B) having a magnetic pole direction facing radially outward, and a sub-magnet (33) between the pair of main magnets (31) having a magnetic pole direction including a component facing the second main magnet. The main magnet has an inner circumferential width that is shorter than its outer circumferential width, the sub-magnet has an outer circumferential width that is shorter than its inner circumferential width, the angle (α) formed by both circumferential end faces of the main magnet is larger than the angle (β) formed by both circumferential end faces of the sub-magnet, and the main magnet and the sub-magnet are held in close contact with each other by an annular holding member (35) made of a non-magnetic material and placed outside them.

[0020] According to this aspect, the outer tapered secondary magnets are held by the inner tapered primary magnets from the radially outer side while being in close contact with the inner tapered primary magnets, and the inner tapered primary magnets are held by a retaining member from the radially outer side. This prevents these magnets from scattering due to radial external forces such as centrifugal force. Furthermore, because the outer tapered secondary magnets are held by the inner tapered primary magnets from the radially outer side, these magnets can be assembled to the outer periphery of the yoke in a circumferentially close contact state without strict dimensional control of the magnets. This reduces the number of processing steps and the cost of dimensional control. Furthermore, it is possible to reduce the demagnetizing field regions that occur at the radially inner and outer corners of the contact points between adjacent main magnets and secondary magnets. This reduces output reduction due to rotor demagnetization. [Effects of the Invention]

[0021] According to the above-described aspect, the magnets can be assembled without strict dimensional control and with fewer processing steps, thereby reducing the manufacturing costs of the rotor and the rotating electric machine. [Brief explanation of the drawings]

[0022] [Figure 1] Cross-sectional view of a motor according to an embodiment [Figure 2] 1 is a rear view of a rotor and a stator according to a first embodiment; [Figure 3] 3 is an enlarged view of a portion III in FIG. 2 of the rotor according to the first embodiment. [Figure 4] Enlarged view of the main part of the rotor according to the first embodiment [Figure 5] (A) Magnetic flux density distribution diagram and (B) demagnetization distribution diagram of a rotor according to a conventional example [Figure 6] (A) Magnetic flux density distribution diagram and (B) demagnetization distribution diagram of the rotor according to the first embodiment [Figure 7] Enlarged view of the main part of the rotor according to the second embodiment [Figure 8] (A) Magnetic flux density distribution diagram and (B) demagnetization distribution diagram of the rotor according to the second embodiment [Figure 9] Enlarged view of a main part of a rotor according to a third embodiment [Figure 10] FIG. 10 is an explanatory diagram showing an exploded view of the main part of the rotor according to the third embodiment. [Figure 11] Enlarged view of a main part of a rotor according to a fourth embodiment [Figure 12] Enlarged view of the main part of the rotor according to the fifth embodiment [Figure 13] Graph showing demagnetization rate of a rotor according to an embodiment [Figure 14] Graph showing demagnetization rate of a rotor according to a conventional example [Figure 15] Enlarged view of a main part of a rotor according to a sixth embodiment [Figure 16] Enlarged view of a main part of a rotor according to a conventional example DETAILED DESCRIPTION OF THE INVENTION

[0023] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a rotating electrical machine to which a rotor according to the present invention is applied will be described in detail with reference to the drawings.

[0024] FIG. 1 is a cross-sectional view of a motor 1 according to an embodiment. As shown in FIG. 1, the motor 1 has a cylindrical case 3 centered on an axis 2, a rotor 4 supported by the case 3 so as to be rotatable about the axis 2, and a stator 5 disposed on the outer periphery of the rotor 4 and fixed to the case 3. In other words, the motor 1 is configured as an inner rotor type radial gap motor. While the motor 1 is used in the position shown in FIG. 1 in which the axis 2 extends horizontally, it may also be used in a position in which the axis 2 extends vertically.

[0025] The case 3 has a case body 6 and a case lid 7 that can be separated in the axial direction, and defines an internal storage space for accommodating the rotor 4 and the stator 5. The case body 6 has a cylindrical side wall 8 and a bottom wall 9 that closes the end of the side wall 8 opposite the case lid 7. A through hole 10 centered on the axis 2 is formed in the bottom wall 9 of the case body 6 and the case lid 7.

[0026] The rotor 4 includes a rotating shaft 11 that extends along the axis 2 and serves as the output shaft of the motor 1, a rotor hub 12 arranged around the rotating shaft 11, a cylindrical yoke 13 (rotor core) provided at the outer end of the rotor hub 12, and a plurality of permanent magnets (simply referred to as magnets 14). The rotor hub 12 may be provided integrally with the rotating shaft 11, or may be provided so as to be rotatable relative to the rotating shaft 11 via a planetary gear mechanism or the like. In either configuration, the rotating shaft 11 rotates as the rotor hub 12 rotates.

[0027] The rotating shaft 11 is rotatably supported by the case body 6 and the case cover 7 via bearings 15. The rotating shaft 11 passes through through holes 10 in the case body 6 and the case cover 7 and protrudes in the axial direction from both sides of the case 3. In other embodiments, the rotating shaft 11 may protrude from only one side of the case 3. The yoke 13 is a rotor core having a substantially cylindrical shape centered on the axis 2, and is formed integrally with the outer edge of the rotor hub 12, rotating integrally with the rotor hub 12. The motor 1 is a permanent magnet synchronous motor, and a plurality of magnets 14 are arranged in a predetermined circumferential arrangement on the outer periphery of the yoke 13. The rotor 4 forms a field element of the motor 1.

[0028] The stator 5 is disposed along a side wall 8 of the case body 6, with a predetermined radial gap between it and the outer surface of the rotor 4. The stator 5 includes a stator core 18 having a plurality of teeth 16 and a teeth retaining ring 17 (stator yoke) disposed outside the teeth 16 to retain the teeth 16, and a plurality of coils 19 wound around the teeth 16. The stator 5 forms the armature of the motor 1. The teeth retaining ring 17 is cylindrical and is disposed about the axis 2. The teeth 16 are aligned circumferentially along the teeth retaining ring 17 and protrude radially inward from the inner surface of the teeth retaining ring 17.

[0029] The case cover 7 has a cover wall 20 that closes the open end of the side wall 8 and a cylindrical duct 21 that extends from the cover wall 20 to the side opposite the case body 6. A fan 22 is integrally provided on the portion of the rotating shaft 11 that extends from the cover wall 20. The fan 22 is disposed within the duct 21 and includes a disk portion 23 disposed radially inward and a blade portion 24 disposed radially outward of the disk portion 23. When the rotating shaft 11 rotates, the fan 22 rotates, and cooling air is sent from the blade portion 24 toward the rotor 4 and the stator 5. Ventilation openings 25, 26 are formed on the outer periphery of the cover wall 20 and the bottom wall 9 of the case body 6. The cooling air enters the storage space through the ventilation opening 25 of the cover wall 20, cools the rotor 4 and the stator 5, and then is discharged to the outside of the storage space through the ventilation opening 26 of the case body 6. [Example]

[0030] FIG. 2 is a rear view of the rotor 4 and stator 5 according to the first embodiment, and FIG. 3 is an enlarged view of part III in FIG. 2 of the rotor 4 according to the first embodiment. As shown in FIGS. 2 and 3, the magnets 14 include a first main magnet 31A having a magnetic pole direction (magnetization direction) facing radially inward, a second main magnet 31B having a magnetic pole direction facing radially outward, and a sub-magnet 33 disposed between the first main magnet 31A and the second main magnet 31B. The sub-magnet 33 has a magnetic pole direction that includes a circumferential component. In other words, the magnets 14 are arranged in a ring shape in a Halbach array. The magnetic pole direction of each magnet 14 is indicated by an arrow in FIG. 3. The magnetic pole direction of the sub-magnet 33 faces the second main magnet 31B.

[0031] The stator 5 has 72 electromagnets each consisting of a tooth 16 and a coil 19. The electromagnets are arranged at equal intervals (every 5°) around the circumference. The rotor 4 has 24 first main magnets 31A, 24 second main magnets 31B, and 48 sub-magnets 33.

[0032] Fig. 4 is an enlarged view of a main portion of the rotor 4 according to the first embodiment. As shown in Figs. 3 and 4, the first main magnet 31A and the second main magnet 31B have the same shape and dimensions. Hereinafter, when the first main magnet 31A and the second main magnet 31B are collectively referred to or when no distinction is made, they may be simply referred to as the main magnet 31. The multiple sub-magnets 33 have the same shape as each other but different shapes from the main magnet 31.

[0033] In a conventional rotor 104 (see FIG. 5) such as that shown in FIG. 14 of Patent Document 2, multiple permanent magnets (simply referred to as magnets 114) are divided by dividing lines extending radially from the axis 2. That is, the actual circumferential width of the magnets 114 increases toward the outside, but the arc-shaped outer surface on the radially outer side of the magnets 114 and the arc-shaped inner surface on the radially inner side have the same central angle. In this specification, the circumferential dimension of the magnets 14, 114 expressed by the central angle is referred to as the circumferential width. Furthermore, the circumferential dimension of the arc-shaped outer surface on the radially outer side of the magnets 14, 114 is referred to as the outer circumferential width, and the circumferential dimension of the arc-shaped inner surface on the radially inner side of the magnets 14, 114 is referred to as the inner circumferential width. Furthermore, the circumferential dimension of the magnet 14 at a position passing through the center between the outer and inner surfaces of the magnets 14 is simply referred to as the circumferential width. In the magnet 114 shown in FIG. 14 of Patent Document 2, the outer circumferential width and the inner circumferential width are equal to each other and are the same as the circumferential width.

[0034] In contrast, in this embodiment, the main magnet 31 has an inwardly tapered curved trapezoid shape in which the inner circumferential width is shorter than the outer circumferential width. In other words, the main magnet 31 has an inwardly tapered wedge shape in which both circumferential end faces narrow radially inward relative to two radial lines extending radially from the axis 2 to pass through both ends of the outer circumferential surface. On the other hand, the sub-magnet 33 has an outwardly tapered curved trapezoid shape in which the outer circumferential width is shorter than the inner circumferential width. In other words, the sub-magnet 33 has an outwardly tapered shape in which both circumferential end faces narrow radially outward relative to two radial lines extending radially from the axis 2 to pass through both ends of the inner circumferential surface.

[0035] In this embodiment, the circumferential width of the main magnet 31 is equal to the circumferential width of the sub-magnet 33. In other embodiments, the circumferential width of the main magnet 31 and the circumferential width of the sub-magnet 33 may be different from each other.

[0036] The main magnet 31 and the sub-magnet 33 have the same thickness (radial dimension). Therefore, the magnet 14 (main magnet 31 and sub-magnet 33) forms a stepless circular outer periphery centered on the axis 2. A holding member 35 is provided on the outer periphery of the magnet 14 to hold the magnet 14 on the surface of the yoke 13 and prevent the magnet 14 from scattering.

[0037] The retaining member 35 is made of a non-magnetic material such as a resin molding material or a non-magnetic metal material so as not to affect the magnetic field produced by the magnets 14. The retaining member 35 is cylindrical and is in close contact with the outer surfaces of all of the main magnets 31 and sub-magnets 33, surrounding them. The retaining member 35 has an inner diameter slightly smaller than the diameter of the outer peripheral surface of the magnets 14 arranged on the outer periphery of the yoke 13, and is attached to the outer peripheral surface of the magnets 14 in an interference fit relationship.

[0038] In another embodiment, the holding member 35 may include, in addition to the cylindrical portion, an annular inner flange (not shown) extending radially inward from one axial end of the cylindrical portion. The multiple magnets 14 may be bonded to the surface of the yoke 13 with an adhesive, or may be bonded to each other with an adhesive.

[0039] The motor 1 is configured as described above. The effects of the motor 1 configured as described above will be described below.

[0040] First, we will explain the magnetic flux density and demagnetization of a typical rotor 104 according to a conventional example, in which multiple magnets 114 are divided by dividing lines extending radially from the axis 2, as shown in FIG. 14 of Patent Document 2. FIG. 5 shows (A) a magnetic flux density distribution diagram and (B) a demagnetization distribution diagram of the rotor 104 according to the conventional example. As shown in FIG. 5(A), the multiple magnets 114 arranged on the outer periphery of the yoke 113 also in the rotor 104 according to the conventional example include multiple first main magnets 131A (see FIG. 16), multiple second main magnets 131B, and multiple sub-magnets 133. The main magnets 131 (131A, 131B) of this example have the same circumferential width as the main magnets 31 of the first embodiment, and the sub-magnets 133 of this example have the same circumferential width as the sub-magnets 33 of the first embodiment.

[0041] In FIG. 5(A), the magnetic field lines of magnet 14 are indicated by dashed lines, and the magnetization direction of magnet 14 is indicated by arrows. The spacing between the magnetic field lines indicates the magnetic flux density, and narrower spacing indicates higher magnetic flux density. As shown in FIG. 5(A), in the conventional rotor 104, magnetic field lines flow in the opposite direction to the magnetization direction at the radially outer corners of sub-magnet 133 and the radially inner corners of second main magnet 131B. In these locations, the magnetic force of sub-magnet 133 is canceled out by the magnetic force of the adjacent second main magnet 131B, thereby decreasing the magnetic field, and the magnetic force of second main magnet 131B is canceled out by the magnetic force of the adjacent sub-magnet 133, thereby decreasing the magnetic field.

[0042] In Figure 5(B), the demagnetization factor at each position on the magnet 14 is indicated by hatching. The demagnetization factor is the rate of change in the amount of magnetic flux before and after high-load driving, and indicates the ratio of the difference obtained by subtracting the amount of magnetic flux at the time of demagnetization from the initial amount of magnetic flux to the initial amount of magnetic flux. The darker the hatching, the greater the demagnetization factor. As shown in Figure 5(B), the demagnetization factor is large at the radially outer corners of the sub-magnet 133 and the radially inner corners of the second main magnet 131B. The presence of areas with a large demagnetization factor and a large demagnetized area means that the magnetic force of the magnet 14 as a whole is reduced.

[0043] Next, the magnetic flux density and demagnetization of the rotor 4 according to the first embodiment will be described. FIG. 6 shows (A) a magnetic flux density distribution diagram and (B) a demagnetization distribution diagram of the rotor 4 according to the first embodiment. Note that the holding member 35 is omitted in FIG. 6. The same applies to FIG. 5. As shown in FIG. 6(A), in the rotor 4 according to this embodiment, compared to the conventional example, the corners of the second main magnet 31B are expanded toward the radially outer corners of the sub-magnet 33, and the corners of the sub-magnet 33 are expanded toward the radially inner corners of the second main magnet 31B. This configuration reduces the cancellation of magnetic forces.

[0044] 6(B), the demagnetization factor is slightly smaller than that of the conventional example at the radially outer corner of the sub-magnet 33, and the demagnetization factor is significantly smaller than that of the conventional example at the radially inner corner of the second main magnet 131B. This increases the magnetic force of the magnet 14 as a whole compared to that of the conventional example.

[0045] As shown in FIG. 4 , in the rotor 4 of this embodiment, the sub-magnets 33 have an outwardly tapered, curved trapezoidal shape with an outer circumferential width shorter than its inner circumferential width, and the main magnets 31 have an inwardly tapered, curved trapezoidal shape with an inner circumferential width shorter than its outer circumferential width. The main magnets 31 and sub-magnets 33 are held in close contact with each other by an annular retaining member 35 made of a non-magnetic material arranged outside them. Therefore, the outer tapered sub-magnets 33 are held in close contact with the inner tapered main magnets 31 from the radially outer side by the inner tapered main magnets 31, and the inner tapered main magnets 31 are held in close contact with each other by the retaining member 35 from the radially outer side. This prevents the magnets 14 from being scattered by radial external forces such as centrifugal force. Furthermore, because the outer tapered sub-magnets 33 are held in close contact with the inner tapered main magnets 31 from the radially outer side, the magnets 14 can be assembled to the outer periphery of the yoke 13 in close contact with each other without strict dimensional control of the magnets 14. This reduces the number of processing steps and the cost of dimensional control.

[0046] Furthermore, the main magnet 31 of this embodiment has an inwardly tapered trapezoidal shape. This reduces the demagnetizing field regions that occur at the radially inner and outer corners of the contact area where adjacent main magnets 31 and sub-magnets 33 come into contact, as shown in Fig. 6, and reduces the demagnetization factor of the rotor 4. This improves the reduction in output due to demagnetization of the rotor 4. The demagnetization factor will be described in detail later with reference to Figs. 13 and 14, along with the demagnetization factors of other embodiments.

[0047] Furthermore, in the motor 1 of this embodiment, a fan 22 is provided on the rotating shaft 11 that is driven to rotate by the rotor 4, and the fan 22 blows air toward the magnets 14 when the rotor 4 rotates. Therefore, the wind blown from the fan 22 cools the magnets 14, thereby reducing torque fluctuations caused by overheating of the magnets 14. [Example]

[0048] A second embodiment of the present invention will be described with reference to Figures 7 and 8. In the following embodiments, the same or similar components as those in the first embodiment will be denoted by the same reference numerals, and duplicated explanations will be omitted. The same applies to the following embodiments unless otherwise specified.

[0049] FIG. 7 is an enlarged view of a main portion of a rotor 4 according to a second embodiment. As shown in FIG. 7, in this embodiment, the main magnets 31 (31A, 31B) have an outwardly tapered, curved trapezoidal shape in which the outer circumferential width is shorter than the inner circumferential width. In other words, the main magnets 31 have an outwardly tapered shape. On the other hand, the sub-magnets 33 have an inwardly tapered, curved trapezoidal shape in which the inner circumferential width is shorter than the outer circumferential width. In other words, the sub-magnets 33 have an inwardly tapered, wedge-like shape.

[0050] The main magnet 31 and the sub-magnets 33 are held in close contact with each other by an annular holding member 35 made of a non-magnetic material located outside them. Therefore, the outer tapered main magnet 31 is held in close contact with the inner tapered sub-magnet 33 from the radially outer side by the inner tapered sub-magnet 33, and the inner tapered sub-magnet 33 is held in close contact with the holding member 35 from the radially outer side. This prevents these magnets 14 from scattering due to radial external forces such as centrifugal force.

[0051] 8A and 8B show a magnetic flux density distribution diagram and a demagnetization distribution diagram, respectively, of the rotor 4 according to the second embodiment. As shown in Fig. 8A, in the rotor 4 according to the present embodiment, compared to the conventional example shown in Fig. 5, the radially outer corners of the sub-magnets 33 are expanded toward the corners of the second main magnets 31B, and the radially inner corners of the second main magnets 31B are expanded toward the corners of the sub-magnets 33. In this configuration, the demagnetization distribution appears as shown in Fig. 8B, but the improvement in the demagnetization rate across the entire magnet 14, as in the first embodiment, could not be confirmed.

[0052] Meanwhile, in this embodiment as well, the outer tapered main magnet 31 is held from the radial outside by the inner tapered sub-magnet 33, so these magnets 14 can be assembled to the outer periphery of the yoke 13 in a state of tight circumferential contact without strict control of the dimensions of the magnets 14. This reduces the number of processing steps and the costs for dimensional control. [Example]

[0053] A third embodiment of the present invention will be described with reference to Figures 9 and 10. In this embodiment, differences from the first embodiment will be described.

[0054] Fig. 9 is an enlarged view of a main portion of a rotor 4 according to a third embodiment. As shown in Fig. 9, in this embodiment, the main magnet 31 and the sub-magnet 33 have the same thickness (radial dimension), while the main magnet 31 forms a gap between itself and the yoke 13. Therefore, a step is formed on the outer circumferential surface of the magnet 14 (main magnet 31 and sub-magnet 33). The holding member 35 is in close contact with the outer surface of the main magnet 31, while forming a gap between itself and the sub-magnet 33. Because the main magnet 31 has an inwardly tapered wedge shape, the main magnet 31 and the sub-magnet 33 are held by the holding member 35 in a state of close contact with each other, similar to the first embodiment.

[0055] Also in this embodiment, the outer tapered main magnet 31 is held from the radial outside by the inner tapered sub-magnet 33, so these magnets 14 can be assembled to the outer periphery of the yoke 13 in a state of tight circumferential contact without strict control of the dimensions of the magnets 14. This reduces the number of processing steps and the costs for dimensional control.

[0056] FIG. 10 is an exploded explanatory diagram showing the main parts of a rotor 4 according to a third embodiment. As shown in FIG. 10, the sub-magnets 33 are arranged at a predetermined interval on the outer circumferential surface of the yoke 13. The distance A between the inner surfaces of two adjacent sub-magnets 33 is smaller than the distance B between the outer surfaces of these sub-magnets 33. The main magnets 31 (31A, 31B) are arranged at a predetermined interval on the inner circumferential surface of the holding member 35. The inner circumferential width of the main magnet 31 (hereinafter referred to as the first inner circumferential width X) is smaller than the outer circumferential width of the main magnet 31 (hereinafter referred to as the first outer circumferential width Y). Furthermore, the first inner circumferential width X of the main magnet 31 is larger than the distance A between the inner surfaces of the sub-magnets 33 arranged on both sides of it in the circumferential direction, and the first outer circumferential width Y of the main magnet 31 is larger than the distance B between the outer surfaces of the sub-magnets 33.

[0057] With the main magnet 31 and the sub-magnet 33 having such dimensions and arrangement, the main magnet 31 abuts against the holding member 35, and a gap is formed between the main magnet 31 and the holding member 35. The sub-magnet 33 abuts against the yoke 13, and a gap is formed between the main magnet 31 and the holding member 35. The formation of gaps between the main magnet 31 and the yoke 13, and between the sub-magnet 33 and the holding member 35, increases the area of ​​the magnet surface exposed to the atmosphere. This suppresses a decrease in output due to heat generation from the rotor 4.

[0058] It should be noted that it is not necessary for there to be an air gap, as long as a gap (magnetic gap) is formed between the magnet 14 and the yoke 13 or the holding member 35. Therefore, a non-magnetic material may be disposed in the gap.

[0059] In particular, since the motor 1 is equipped with the fan 22 that blows air toward the main magnet 31 and the sub magnet 33, the air blown from the fan 22 passes through these gaps, effectively cooling the main magnet 31 and the sub magnet 33. This further reduces torque irregularities caused by overheating of the magnet 14.

[0060] Furthermore, in this embodiment, the demagnetization field regions generated at the corners of adjacent main magnets 31 and sub-magnets 33 are reduced, effectively reducing the demagnetization factor of the rotor 4, thereby significantly improving the reduction in output due to demagnetization of the rotor 4. The demagnetization factor will be described in detail later. [Example]

[0061] A fourth embodiment of the present invention will be described with reference to Fig. 11. In this embodiment as well, differences from the first embodiment will be described.

[0062] Fig. 11 is an enlarged view of a main portion of a rotor 4 according to a fourth embodiment. As shown in Fig. 11, in this embodiment, the radial thickness of the main magnets 31 (31A, 31B) is greater than the radial thickness of the sub-magnets 33, and a gap is formed between the sub-magnets 33 and the holding member 35.

[0063] The first inner circumferential width X of the main magnet 31 (see the symbols in FIG. 10; the same applies below) is equal to the distance A between the inner surfaces of the sub-magnets 33 arranged on both sides of it in the circumferential direction, and the first outer circumferential width Y of the main magnet 31 is greater than the distance B between the outer surfaces of the sub-magnets 33. Therefore, not only the sub-magnets 33 but also the main magnet 31 are in close contact with the yoke 13.

[0064] In this way, in this embodiment, by increasing the radial thickness of the main magnet 31, a gap is formed between the sub-magnet 33 and the holding member 35. This reduces the demagnetizing field area at the corners of the sub-magnet 33 near the gap. As a result, the reduction in output due to demagnetization of the rotor 4 is improved.

[0065] If the radial thickness of one of the main magnet 31 and the sub-magnet 33 is greater than the radial thickness of the other, a gap is formed between the main magnet 31 or the sub-magnet 33 and the yoke 13, or between the main magnet 31 or the sub-magnet 33 and the retaining member 35. This configuration reduces the demagnetizing field area at the corners of the magnet 14 near the gap, thereby improving the output reduction due to demagnetization of the rotor 4. [Example]

[0066] A fifth embodiment of the present invention will be described with reference to Fig. 12. In this embodiment as well, differences from the first embodiment will be described.

[0067] Fig. 12 is an enlarged view of a main portion of the rotor 4 according to the fifth embodiment. As shown in Fig. 12, in this embodiment, the radial thickness of the sub-magnets 33 is greater than the radial thickness of the main magnets 31 (31A, 31B), and a gap is formed between the main magnets 31 and the yoke 13.

[0068] The first inner circumferential width X of the main magnet 31 (see the symbols in FIG. 10; the same applies below) is greater than the distance A between the inner surfaces of the sub-magnets 33 arranged on both sides of it in the circumferential direction, and the first outer circumferential width Y of the main magnet 31 is equal to the distance B between the outer surfaces of the sub-magnets 33. Therefore, not only the main magnet 31 but also the sub-magnets 33 are in close contact with the holding member 35.

[0069] In this embodiment, the radial thickness of the sub-magnet 33 is greater than the radial thickness of the main magnet 31, so a gap is formed between the main magnet 31 and the yoke 13. This reduces the demagnetizing field area at the corners of the magnet 14 near the gap, improving output reduction due to demagnetization of the rotor 4.

[0070] Next, the effects of the motor 1 according to the embodiment will be described with reference to FIGS.

[0071] Fig. 13 is a graph showing the demagnetization factor of the rotor 4 according to the embodiment, and Fig. 14 is a graph showing the demagnetization factor of the rotor 104 according to the conventional example. Fig. 13 shows the demagnetization factors of the rotor 4 according to the first and third to fifth embodiments. Fig. 14 shows the demagnetization factor of the conventional example (configuration shown in Fig. 5) corresponding to the first embodiment, and the rotor 104 according to the conventional example corresponding to the third to fifth embodiments.

[0072] Each of the rotors 104 according to the conventional examples has a configuration in which the magnets 114 are divided by dividing lines extending radially from the axis 2. As shown in FIG. 5, the rotor 104 according to the first conventional example has no gaps on either the radially inner or radially outer sides of the magnets 114. The rotor 104 according to the third conventional example has gaps on both the radially inner and radially outer sides of the magnets 114, similar to the third embodiment shown in FIG. 9. The rotor 104 according to the fourth conventional example has no gaps on the radially inner sides of the magnets 114, but has gaps on the radially outer sides, similar to the fourth embodiment shown in FIG. 11. The rotor 104 according to the fifth conventional example has gaps on the radially inner sides of the magnets 114, but no gaps on the radially outer sides, similar to the fifth embodiment shown in FIG. 12.

[0073] As shown in FIG. 14, in the first conventional example, the demagnetization factor of the rotor 104 was 2.91%. In contrast, in the first embodiment, the magnet 14 was configured as shown in FIG. 4, and thus the demagnetization factor of the rotor 4 was improved to 2.72% (see FIG. 13). As shown in FIG. 14, in the fifth conventional example in which a gap was formed radially inside the magnet 114, no improvement in the demagnetization factor of the rotor 104 was observed compared to the first conventional example. On the other hand, in the fifth embodiment, as shown in FIG. 13, a gap was formed radially inside the main magnet 31, and thus the demagnetization factor of the rotor 4 was improved to 2.66%. Furthermore, in the third embodiment, the demagnetization factor of the rotor 4 was significantly improved to 1.38%, and in the fourth embodiment, the demagnetization factor of the rotor 4 was improved even more significantly to 1.28%. As shown in FIG. 14, in the third and fourth conventional examples in which a gap was formed radially outside the magnet 114, the demagnetization factor of the rotor 104 was improved to 1.83% and 1.73%, respectively, but the improvement was not as great as in the third and fourth embodiments.

[0074] In this embodiment, one of the main magnet 31 and the sub-magnet 33 has an outwardly tapered trapezoidal shape, and the other of the main magnet 31 and the sub-magnet 33 has an inwardly tapered trapezoidal shape, thereby improving the demagnetization rate of the rotor 4. [Example]

[0075] Next, a sixth embodiment of the present invention will be described with reference to Fig. 15. A rotor 4 according to the sixth embodiment has a similar configuration to that of the third embodiment shown in Fig. 9.

[0076] Specifically, the main magnet 31 has an inwardly tapered trapezoidal shape with an inner circumferential width shorter than its outer circumferential width, and the sub-magnet 33 has an outwardly tapered trapezoidal shape with an outer circumferential width shorter than its inner circumferential width. The main magnet 31 abuts against the holding member 35, forming a gap between it and the yoke 13, and the sub-magnet 33 abuts against the yoke 13, forming a gap between it and the holding member 35. The main magnet 31 and the sub-magnet 33 are held in close contact with each other by the annular holding member 35 made of a non-magnetic material and arranged outside them.

[0077] 15, when both circumferential end faces of the first main magnet 31A are extended, they intersect at an angle α at an intersection point a radially inward from the first main magnet 31A. When both circumferential end faces of the second main magnet 31B are extended, they intersect at an angle α at an intersection point b radially inward from the second main magnet 31B. When both circumferential end faces of the sub-magnet 33 are extended, they intersect at an angle β at an intersection point c radially outward from the sub-magnet 33. When the end faces of the first main magnet 31A and the second main magnet 31B on the side separating them in the circumferential direction are extended, they intersect at an angle β at an intersection point d radially inward from the intersection points a and b.

[0078] The angle α formed by both circumferential end faces of the main magnet 31 is equal to or greater than the angle β formed by both circumferential end faces of the sub-magnet 33 (α≧β). The angle α formed by both end faces of the main magnet 31 may be, for example, 1.5 times the angle β formed by both end faces of the sub-magnet 33 (α=1.5β), as shown in FIG. 15 . In this case, the angle (2β) formed by the line connecting the intersection points adb is twice the angle (β) formed by the line connecting the intersection points acb. The rotor 4 of this embodiment has this configuration.

[0079] Fig. 16 is an enlarged view of a main portion of a rotor 104 according to a conventional example. This rotor 104 has the same configuration as that shown in Fig. 5. That is, the multiple magnets 114 (first main magnet 131A, second main magnet 131B, and sub-magnet 133) are divided by dividing lines extending radially from the axis 2. Although not shown in Fig. 5 as mentioned above, a holding member 135 is provided on the outer periphery of the magnet 114.

[0080] In contrast, the rotor 4 of this embodiment has the configuration described above with reference to Fig. 15. Specifically, the angle α between both circumferential end faces of the main magnet 31 is larger than the angle β between both circumferential end faces of the sub-magnet 33, and the main magnet 31 and the sub-magnet 33 are held in close contact with each other by annular holding members 35 made of a non-magnetic material and arranged outside them.

[0081] As a result, the outer tapered secondary magnets 33 are held by the inner tapered primary magnets 31 from the radially outer side while in close contact with the inner tapered primary magnets 31, and the inner tapered primary magnets 31 are held by the retaining members 35 from the radially outer side. This prevents these magnets 14 from scattering due to radial external forces such as centrifugal force. Furthermore, because the outer tapered secondary magnets 33 are held by the inner tapered primary magnets 31 from the radially outer side, these magnets 14 can be assembled to the outer periphery of the yoke 13 while in close contact with each other circumferentially without strict dimensional control of the magnets 14. This reduces the number of processing steps and the cost of dimensional control. Furthermore, the demagnetizing field regions generated at the radially inner and outer corners of the contact points where adjacent main magnets 31 and secondary magnets 33 come into contact are reduced, thereby improving output reduction due to demagnetization of the rotor 4.

[0082] Although the description of specific embodiments has been completed above, the present invention is not limited to the above-described embodiments and examples, and can be widely modified and implemented. For example, in the above-described embodiments, the rotor according to the present invention is applied to the rotor 4 of the motor 1, but it may also be applied to the rotor 4 of a generator. Furthermore, the specific configuration, arrangement, quantity, material, etc. of each member and part can be changed as appropriate without departing from the spirit of the present invention. Furthermore, not all of the components shown in the above-described embodiments are necessarily required, and can be selected as appropriate. [Explanation of symbols]

[0083] 1: Motor (an example of a rotating electrical machine) 4: Rotor 5: Stator 11: Rotation axis 13: Yoke (rotor core) 14: Magnet 22: Fan 31: Main magnet 31A: 1st main magnet 31B: 2nd main magnet 33: Sub magnet 35: Holding member A: Distance between inner surfaces of the sub-magnets 33 B: Distance between the outer surfaces of the sub-magnets 33 X: First inner circumferential width of the main magnet 31 Y: First outer circumferential width of the main magnet 31 α: angle between both end faces of the main magnet 31 β: angle between both end faces of the sub-magnet 33

Claims

1. A rotor of a rotating electric machine, a plurality of magnets arranged in a predetermined arrangement in the circumferential direction; a yoke disposed radially inside the magnet, the predetermined arrangement is a Halbach array in which a sub-magnet having a magnetic pole direction including a component facing toward the second main magnet is disposed between a pair of main magnets including a first main magnet having a magnetic pole direction facing radially inward and a second main magnet having a magnetic pole direction facing radially outward, the sub-magnets have an outer tapered trapezoidal shape with an outer circumferential width shorter than an inner circumferential width, and the main magnets have an inner tapered trapezoidal shape with an inner circumferential width shorter than the outer circumferential width, the main magnet and the sub-magnet are held in close contact with each other by an annular holding member made of a non-magnetic material and arranged outside the main magnet and the sub-magnet, an inner circumferential width of the main magnet is larger than the distance between the inner surfaces of the sub-magnets arranged on both sides of the main magnet in the circumferential direction, and an outer circumferential width of the main magnet is larger than the distance between the outer surfaces of the sub-magnets, the main magnet abuts against the holding member and forms a gap between the main magnet and the yoke; The sub-magnet abuts against the yoke, and a gap is formed between the sub-magnet and the holding member.

2. 2. The rotor for a rotating electric machine according to claim 1, wherein a radial thickness of one of the main magnets and the sub-magnets is greater than a radial thickness of the other of the main magnets and the sub-magnets.

3. 3. The rotor for a rotating electric machine according to claim 2, wherein the radial thickness of said main magnet is greater than the radial thickness of said sub-magnet.

4. A rotor of a rotating electric machine as described in claim 1, wherein the angle of inclusion formed by both circumferential end faces of the main magnet is larger than the angle of inclusion formed by both circumferential end faces of the sub-magnet.

5. A rotor according to any one of claims 1 to 4; a stator provided outside the rotor; a rotating shaft that is rotationally driven by the rotor; a fan provided on the rotating shaft for blowing air toward the magnet when the rotating shaft rotates.

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