Rotor and motor

Abstract

Provided are a rotor and an electric motor capable of reducing torque ripple while maintaining average torque. In a rotor (3), a first circumferential end surface (23) and a second circumferential end surface (24) of a plurality of permanent magnets (11) protrude in the circumferential direction with respect to an imaginary plane (32) connecting the circumferential edge of an inner end surface (26) and the circumferential edge of an outer end surface (25). The first circumferential end face (23) and the second circumferential end face (24) are magnetic pole faces, and the homopolar magnetic pole faces of two permanent magnets (11) adjacent to each other in the circumferential direction (C1) among the plurality of permanent magnets (11) are arranged so as to face each other in the circumferential direction (C1). The circumferential length (L1) of the outer end surface (25) is shorter than the circumferential length (L2) of the inner end surface (26). In the rotor core (9), a plurality of holes (41, 42) are provided between the permanent magnets adjacent to each other in the circumferential direction (C1) of the plurality of permanent magnets (11).

Description

Technical Field

[0001] The present invention relates to a rotor and a motor, and in particular to a rotor including a plurality of permanent magnets and a motor including the rotor. Background Art

[0002] Patent document 1 discloses a rotor having a rotor core and a plurality of permanent magnets embedded in the rotor core. One or the other of a pair of circumferential end faces of the permanent magnet protrudes in the circumferential direction relative to a plane connecting the inner end and the outer end of the end face. In addition, in the rotor core, a large through hole is provided between the permanent magnets in the axial direction.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent No. 6083523 Summary of the invention

[0006] In the rotor described in Patent Document 1, since one or both of a pair of circumferential end faces of the permanent magnet protrude circumferentially relative to the plane connecting the inner end and the outer end of the end face, the volume of the permanent magnet increases. Therefore, the magnetic flux density in the rotor is high, and as a result, the average torque of the motor is large. However, in Patent Document 1, neither attention is paid to nor any proposal is made for eliminating torque pulsation that causes vibration and noise.

[0007] The present invention has been made in view of the above-mentioned situation, and an object of the present invention is to provide a rotor and a motor capable of reducing torque ripple while maintaining average torque.

[0008] A rotor of one embodiment of the present invention comprises a rotor core, a plurality of permanent magnets and a rotating shaft. The rotor core has a plurality of magnet arrangement holes arranged in a circumferential direction. The plurality of permanent magnets are respectively arranged in the plurality of magnet arrangement holes. The rotating shaft is fixed to the rotor core, with the axis as the center of rotation. The plurality of permanent magnets respectively have an inner end face, an outer end face and a pair of side faces. The inner end face faces the axis of the rotating shaft. The outer end face faces the direction opposite to the axis of the rotating shaft. The pair of side faces protrude in the circumferential direction relative to an imaginary plane connecting the circumferential edge of the inner end face and the circumferential edge of the outer end face, respectively. The pair of side faces are magnetic pole faces, and the magnetic pole faces of the same poles of two permanent magnets adjacent in the circumferential direction among the plurality of permanent magnets are arranged opposite to each other in the circumferential direction. The circumferential length of the outer end face is shorter than the circumferential length of the inner end face. In the rotor core, a plurality of holes are provided between the circumferential directions of the plurality of permanent magnets.

[0009] An electric motor according to one aspect of the present invention includes the above-mentioned rotor and a stator.

[0010] According to the rotor and the motor of one aspect of the present invention, it is possible to reduce torque ripple while maintaining average torque. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 It is a top view of the electric motor according to the first embodiment.

[0012] Figure 2 It is a partially enlarged plan view of the rotor of the electric motor according to the first embodiment.

[0013] Figure 3 It is a perspective view of the permanent magnet of the rotor according to the first embodiment.

[0014] Figure 4 It is a schematic diagram showing the magnetic flux distribution in the electric motor according to the first embodiment.

[0015] Figure 5 It is a partially enlarged schematic diagram showing the magnetic flux distribution in the electric motor according to the first embodiment.

[0016] Figure 6 It is a partially enlarged plan view of the rotor of the electric motor according to the second embodiment.

[0017] Figure 7 It is a partially enlarged plan view of a rotor of an electric motor according to a third embodiment. DETAILED DESCRIPTION

[0018] (Implementation Method)

[0019] Hereinafter, the rotor and the motor of the embodiment of the present invention will be described in detail with reference to the accompanying drawings. However, the figures described in the following embodiments are schematic diagrams, and the size and thickness ratios of the components may not necessarily reflect the actual size ratios. In addition, the structure described in the following embodiments is only an example of the present invention. The present invention is not limited to the following embodiments, and various changes can be made according to the design, etc., if the effects of the present invention can be achieved.

[0020] (First embodiment)

[0021] (1) Overview of electric motors

[0022] use Figure 1 to Figure 3 An electric motor 1 according to a first embodiment of the present invention will be described. The electric motor 1 is an inner rotor type motor. Figure 1 It is a plan view of the electric motor 1 according to the first embodiment. Figure 2 It is a partially enlarged plan view of the rotor 3 of the electric motor 1 according to the first embodiment. Figure 3 It is a perspective view of the permanent magnet 11 of the rotor 3 according to the first embodiment.

[0023] like Figure 1 As shown in FIG. 1 , the motor 1 includes a stator 2 and a rotor 3. In the following description, the direction in which the axis 14 (described later) of the rotating shaft 10 (described later) extends is referred to as the axis direction, and the circumferential direction of the rotor 3 is referred to as the circumferential direction C1. In addition, the situation observed from the axis direction is referred to as "in a top view". In addition, the direction from a predetermined position in the motor 1 toward the axis is referred to as "radially inward". The direction from a predetermined position in the motor 1 toward a position opposite to the axis is referred to as "radially outward".

[0024] The stator 2 has a stator core 4 and a plurality of ( Figure 1 The stator core 4 is a laminated core formed by laminating a plurality of electromagnetic steel sheets in the thickness direction. The stator core 4 has a ring-shaped core back 7 and a plurality of (in Figure 1 The plurality of teeth 8 are arranged at regular intervals along the circumferential direction C1 on the inner circumferential surface of the core back 7 and extend radially inward. The plurality of coils 5 correspond to the plurality of teeth 8, respectively, and each coil 5 is formed by winding a conductor around the corresponding tooth 8.

[0025] The rotor 3 is an IPM (Interior Permanent Magnet) type rotor (Rotor) in which a permanent magnet is embedded in the rotor core. More specifically, the rotor 3 has a so-called spoke-type rotor structure in which a pair of magnetic pole faces of the magnet are arranged in the circumferential direction. The rotor 3 is arranged radially inside the stator 2 and includes a rotor core 9, a rotating shaft 10, and a plurality of (in Figure 1 The permanent magnets 11 are 10 in the figure. The permanent magnets 11 are components for generating magnetic flux that serves as a driving force for the rotor 3, and are magnetized so that the direction of the magnetic poles is along the circumferential direction C1 of the rotor core 9.

[0026] The motor 1 operates as follows. Three-phase currents having a phase difference of 120° in electrical angle are supplied to the plurality of coils 5 through a power supply connection portion, and the stator 2 is excited to generate a rotating magnetic field. The rotating magnetic field interacts with the magnetic field generated by the permanent magnet 11 provided on the rotor 3 to generate a rotating torque on the rotor 3, and as a result, the rotor 3 rotates around the axis 14.

[0027] (2) Rotor

[0028] The structure and function of the rotor 3 will be described.

[0029] (2-1) Rotor core

[0030] The rotor core 9 is a laminated core formed by laminating a plurality of electromagnetic steel sheets in the thickness direction. The lamination direction of the plurality of electromagnetic steel sheets is along the axis direction (hereinafter referred to as the axis direction). The rotor core 9 has a circular axial hole 12 and is formed in a cylindrical shape. The axial hole 12 is formed in the center of the rotor core 9, which penetrates the rotor core 9 in the axis direction and opens at both end surfaces. The rotor core 9 has a plurality of (in Figure 1 There are 10) outer parts 91 and inner parts 92. The plurality of outer parts 91 are arranged along the circumferential direction C1, and magnet configuration holes 13 are formed between the adjacent outer parts 91 in the circumferential direction C1. The inner part 92 is an annular part that connects the radial inner ends of the plurality of outer parts 91, that is, the parts of the plurality of outer parts 91 that are closest to the axis 14. Through the above-mentioned structure, a plurality of magnet configuration holes 13 arranged along the circumferential direction C1 are formed. In this embodiment, the radial outer side of the magnet configuration hole 13 is open. In addition, the magnet configuration hole 13 is through-through in the axial direction, but it may also have a bottom in the axial direction.

[0031] (2-2) Rotation axis

[0032] The rotating shaft 10 is a cylindrical member, and has an axis 14 serving as a rotation center. The rotating shaft 10 is inserted into and fixed to the axis hole 12 of the rotor core 9 .

[0033] (2-3)Permanent magnet

[0034] The plurality of permanent magnets 11 are inserted into the corresponding magnet arrangement holes 13 of the rotor core 9 and fixed using adhesive etc. The permanent magnets 11 are ferrite sintered magnets. The permanent magnets 11 may also be samarium cobalt permanent magnets, neodymium magnets etc.

[0035] The permanent magnet 11 has substantially the same shape and size as the magnet arrangement hole 13. Therefore, the shape of the permanent magnet 11 will be described in detail below, and the description of the shape of the magnet arrangement hole 13 will be omitted.

[0036] The permanent magnets 11 are substantially rectangular parallelepiped in shape and radially elongated spoke-shaped in a plan view (that is, the long sides of the permanent magnets 11 are along the radial direction of the rotor 3 ), and are arranged along the circumferential direction C1 .

[0037] The magnetization direction of the permanent magnet 11 is parallel to the circumferential direction C1 of the rotor 3, that is, two permanent magnets 11 adjacent to each other in the circumferential direction C1 are magnetized in such a way that the two magnetic pole faces facing each other in the circumferential direction C1 become the same pole. Figure 2 As shown, there is a magnetic pole center line 31 as an imaginary line extending radially outward from the axis 14 between the two permanent magnets 11 , and the two permanent magnets 11 are arranged axially symmetrically about the magnetic pole center line 31 in a plan view.

[0038] like Figure 2 and Figure 3As shown, the permanent magnet 11 has an upper surface 21, a lower surface 22, a first circumferential end face 23 (side), a second circumferential end face 24 (side), an outer end face 25 (radially outer end face) and an inner end face 26 (radially inner end face). When viewed from above, the first circumferential end face 23 and the second circumferential end face 24 extend in the radial direction, and the outer end face 25 and the inner end face 26 extend in the circumferential direction C1. The length of the first circumferential end face 23 and the length of the second circumferential end face 24 are more than twice and less than 20 times the length of the outer end face 25 and the length of the inner end face 26. As a result, the area of ​​the rotor core 9 can be effectively utilized.

[0039] The upper surface 21 and the lower surface 22 are flat surfaces and have the same shape in a plan view.

[0040] The first circumferential end surface 23 and the second circumferential end surface 24 are side surfaces facing the circumferential direction C1 and are also magnetic pole surfaces.

[0041] The first circumferential end surface 23 is a protruding surface that protrudes in the circumferential direction C1 relative to the imaginary plane 32 connecting the inner end and the outer end thereof. The second circumferential end surface 24 is a protruding surface that protrudes in the circumferential direction C1 relative to the imaginary plane 32 connecting the inner end and the outer end thereof. According to the above-mentioned structure, by making the effective area of ​​the magnetic pole surface of the permanent magnet 11 larger, the magnetic flux is larger, and thus the average torque of the motor 1 is higher.

[0042] The first circumferential end face 23 has a first curved surface 23A and a first plane 23B. The first curved surface 23A extends from the radial outer side to the radial inner side. The first curved surface 23A is a smooth curved surface protruding along the circumferential direction C1, and is a curve when viewed from above. The first plane 23B is arranged on the radial inner side of the first curved surface 23A. The first plane 23B is a plane and is a straight line when viewed from above. The first plane 23B is parallel to the magnetic pole center line 31 when viewed from above. Through the above-mentioned structure, it is possible to ensure that the circumferential width of the radial inner part of the permanent magnet 11, that is, the part closer to the axis 14 than the center of the permanent magnet 11, is larger. In addition, the radial length of the first plane 23B is less than 50% of the radial length of the entire first circumferential end face 23.

[0043] The second circumferential end face 24 has a second curved surface 24A and a second plane 24B. The second curved surface 24A extends from the radial outer side to the radial inner side. The second curved surface 24A is a smooth curved surface protruding along the circumferential direction C1, and is a curve when viewed from above. The second plane 24B is arranged on the radial inner side of the second curved surface 24A. The second plane 24B is a plane and is a straight line when viewed from above. The second plane 24B is parallel to the magnetic pole center line 31 when viewed from above. Through the above-mentioned structure, it is possible to ensure that the circumferential width of the radial inner part of the permanent magnet 11 is larger. In addition, the radial length of the second plane 24B is less than 50% of the radial length of the entire second circumferential end face 24.

[0044] The outer end surface 25 is a plane, and is located radially outside the permanent magnet 11. The outer end surface 25 extends substantially along the circumferential direction C1 in a plan view.

[0045] The inner end surface 26 is a flat surface, and is located radially inward of the permanent magnet 11. The inner end surface 26 extends substantially along the circumferential direction C1 in a plan view.

[0046] The circumferential length L1 of the outer end face 25 is shorter than the circumferential length L2 of the inner end face 26. Specifically, the circumferential length L1 of the outer end face 25 is in the range of 60% to 80% of the circumferential length L2 of the inner end face 26. With the above-mentioned structure, the normal line of the first circumferential end face 23 and the normal line of the second circumferential end face 24 are directed radially outward as they are radially outward. As a result, the magnetic flux coming out of the first curved surface 23A of the first circumferential end face 23 and the second curved surface 24A of the second circumferential end face 24 tends to be directed radially outward, that is, toward the stator 2 side. Therefore, the torque of the motor 1 can be further improved.

[0047] (2-4) Holes

[0048] In the rotor core 9, two holes 41 and 42 are provided between two permanent magnets 11 adjacent to each other in the circumferential direction C1 among the plurality of permanent magnets 11. The two holes 41 and 42 are respectively through holes extending along the axial direction of the rotating shaft 10. The two holes 41 and 42 are provided at the outer periphery of the rotor core 9. The holes 41 and 42 are arranged along the circumferential direction C1. The holes 41 and 42 are, for example, significantly smaller than the magnet arrangement hole 13. For example, the total area of ​​the two holes 41 and 42 is less than 20% of the area of ​​one magnet arrangement hole 13. The two holes 41 and 42 are symmetrically arranged about the magnetic pole center line 31. In this embodiment, the holes 41 and 42 are respectively circular when viewed from above.

[0049] use Figure 4 and Figure 5 denoted by . Magnetic flux distribution in the rotor 3. Figure 4 It is a schematic diagram showing the magnetic flux distribution in the electric motor 1 according to the first embodiment. Figure 5 1 is a partially enlarged schematic diagram showing the magnetic flux distribution in the motor 1 of the first embodiment. The magnetic lines of force M come out of the permanent magnet 11 and extend radially outward of the permanent magnet 11. In addition, the magnetic lines of force M extend separately in a manner avoiding the holes 41 and 42 having a larger magnetic resistance than the surroundings. In other words, the magnetic lines of force M are divided into three locations: between the holes 41 and 42, between the permanent magnet 11 and the hole 41, and between the permanent magnet 11 and the hole 42, and the three locations are used as channels respectively.

[0050] As described above, by providing the holes 41 and 42 between the two permanent magnets 11 of the rotor core 9, it is possible to ensure multiple magnetic flux paths between the adjacent permanent magnets 11, thereby reducing torque pulsation. Furthermore, if the difference in magnetic flux density between the three locations that serve as magnetic flux paths (between the holes 41 and 42, between the permanent magnet 11 and the hole 41, and between the permanent magnet 11 and the hole 42) is small, torque pulsation is reduced.

[0051] In particular, since the passages of the magnetic flux formed by the two holes 41 and 42 are symmetrical about the magnetic pole center line 31, the torque ripple is further reduced.

[0052] The two holes 41 and 42 will be described in further detail.

[0053] The two holes 41 and 42 are arranged at a position where the magnetic flux density between the two holes 41 and 42 when there is no load is less than ±40% of the magnetic flux density between the permanent magnet 11 and the hole closest to the permanent magnet 11 when there is no load. Therefore, the difference in the magnetic flux density in the channels of multiple magnetic fluxes is small, so the torque pulsation is reduced. In addition, the distance between the holes 41 and 42 can also be set to ±85% of the distance between the permanent magnet 11 and the hole 41, or between the permanent magnet 11 and the hole 42.

[0054] The two holes 41 and 42 are provided at the outer peripheral portion of the rotor core 9, that is, in the region of the rotor core 9 that is farther from the center of the rotor core 9 as viewed from the axis 14. In this way, since the plurality of holes 41 and 42 are provided at positions away from the axis 14, the flow of magnetic flux near the stator 2 can be adjusted, and thus the torque pulsation can be reduced. In particular, in this embodiment, the two holes 41 and 42 are arranged near the outer peripheral edge of the rotor core 9, so the above-mentioned effect is high.

[0055] In the present embodiment, since the plurality of holes 41 and 42 penetrate in the axial direction, the effect of making the magnetic resistance different from the surroundings is high, and as a result, it contributes to reducing the torque ripple.

[0056] (Variation Example)

[0057] The above-mentioned embodiment is only one of various embodiments of the present invention. As long as the purpose of the present invention can be achieved, the above-mentioned embodiment can be variously changed according to the design, etc. The following lists the modified examples of the above-mentioned embodiment. The modified examples described below can be appropriately combined and applied.

[0058] (1) Modifications of the electric motor

[0059] The rotor core may be a powder core whose main component is a powder material obtained by pressure-molding a powdered magnetic body.

[0060] (2) Modification of magnet arrangement hole

[0061] The shape, number and position of the magnet arrangement holes and the permanent magnets are not limited.

[0062] The side surfaces of the permanent magnet may also consist only of curved surfaces.

[0063] The pair of side surfaces of the permanent magnet may have shapes different from each other.

[0064] All permanent magnets may not be of the same shape or size.

[0065] (3) Modification examples of magnets

[0066] The magnet may be a bonded magnet formed by mixing, kneading and molding magnet powder of a hard magnetic material and a binder such as resin or rubber, or a sintered magnet formed by sintering magnet powder at a high temperature.

[0067] (Second embodiment)

[0068] use Figure 6 The electric motor 1 according to the second embodiment will be described. Figure 6 It is a partially enlarged plan view of the rotor 3 of the electric motor 1 of the second embodiment. The basic structure and operation of the electric motor 1 of the second embodiment are the same as those of the electric motor 1 of the first embodiment, and therefore the following description will focus on the differences.

[0069] On the outside 91 of the rotor core 9, two holes 41A and 42A are provided between two permanent magnets 11 adjacent to each other in the circumferential direction C1 among the plurality of permanent magnets 11. The two holes 41A and 42A are respectively through holes extending along the axial direction of the rotating shaft 10. The two holes 41A and 42A are provided on the outer periphery of the rotor core 9. The holes 41A and 42A are arranged along the circumferential direction C1. The holes 41A and 42A are, for example, significantly smaller than the magnet arrangement hole 13. The two holes 41A and 42A are symmetrically arranged about the magnetic pole center line 31. The holes 41A and 42A are respectively elliptical in a plan view. Specifically, the major axis of the holes 41A and 42A is approximately along the radial direction, and the minor axis is approximately along the circumferential direction C1.

[0070] As described above, by providing the holes 41A and 42A between the permanent magnets 11 of the rotor core 9, the magnetic resistance of this portion is large, and multiple magnetic flux paths can be ensured, so that the torque pulsation can be reduced. Furthermore, if the difference in magnetic flux density between the three locations that serve as magnetic flux paths (between the holes 41A and 42A, between the permanent magnet 11 and the hole 41A, and between the permanent magnet 11 and the hole 42A) is small, the torque pulsation is reduced.

[0071] The two holes 41A and 42A will be described in further detail.

[0072] The two holes 41A and 42A are provided at positions where the magnetic flux density between the two holes 41A and 42A when unloaded is less than ±40% of the magnetic flux density between the permanent magnet 11 and the hole closest to the permanent magnet 11 when unloaded. Therefore, the difference in magnetic flux density in the channels of multiple magnetic fluxes is small, so torque ripple is reduced.

[0073] The two holes 41A and 42A are provided at the outer peripheral portion of the rotor core 9, that is, in a region in the rotor core 9 that is farther from the center of the rotor core 9 as viewed from the axis 14. In this way, since the plurality of holes 41A and 42A are provided at positions away from the axis 14, the flow of magnetic flux near the stator 2 can be adjusted, thereby reducing torque pulsation. In particular, in this embodiment, the two holes 41A and 42A are arranged near the outer peripheral edge of the rotor core 9, so the above-mentioned effect is high.

[0074] (Third embodiment)

[0075] use Figure 7 The electric motor 1 according to the third embodiment will be described. Figure 7 It is a partially enlarged plan view of the rotor 3 of the motor 1 of the third embodiment. The basic structure and operation of the motor 1 of the third embodiment are the same as those of the motor 1 of the first embodiment, so the following description will focus on the differences.

[0076] On the outside 91 of the rotor core 9, four holes 41B, 42B, 43B, and 44B are provided between two permanent magnets 11 adjacent to each other in the circumferential direction C1 among the plurality of permanent magnets 11. The four holes 41B, 42B, 43B, and 44B are through holes extending along the axial direction of the rotating shaft 10. The four holes 41B, 42B, 43B, and 44B are provided on the outer periphery of the rotor core 9. The holes 41B, 42B, 43B, and 44B are arranged along the circumferential direction C1, respectively. The holes 41B and 42B are, for example, significantly smaller than the magnet arrangement hole 13. The group of holes 41B and 42B and the group of holes 43B and 44B are symmetrically arranged about the magnetic pole center line 31. The holes 41B, 42B, 43B, and 44B are circular when viewed from above.

[0077] As described above, by providing the holes 41B, 42B, 43B, and 44B between the permanent magnets 11 of the rotor core 9, the magnetic resistance of this portion is large, and multiple magnetic flux paths can be ensured, thereby reducing torque pulsation. Furthermore, if the difference in magnetic flux density at the five locations serving as magnetic flux paths is small, torque pulsation is easily reduced.

[0078] The four holes 41B, 42B, 43B, and 44B will be described in further detail.

[0079] The four holes 41B, 42B, 43B, and 44B are provided at positions where the magnetic flux density between the four holes 41B, 42B, 43B, and 44B when no load is less than ±40% of the magnetic flux density between the permanent magnet 11 and the hole closest to the permanent magnet 11 when no load is applied. Therefore, the difference in magnetic flux density in the channels of the plurality of magnetic fluxes is small, and thus the torque pulsation is reduced.

[0080] The four holes 41B, 42B, 43B, and 44B are provided at the outer periphery of the rotor core 9, that is, in the region of the rotor core 9 that is farther from the center of the rotor core 9 as viewed from the axis 14. In this way, since the plurality of holes 41B, 42B, 43B, and 44B are provided at positions away from the axis 14, the flow of magnetic flux near the stator 2 can be adjusted, and thus the torque pulsation can be reduced. In particular, in this embodiment, the four holes 41B, 42B, 43B, and 44B are arranged near the outer periphery of the rotor core 9, so the above-mentioned effect is high.

[0081] (Deformation example of hole)

[0082] The number of holes may be 3 or 5 or more.

[0083] The hole may not penetrate the rotor core 9.

[0084] The shape of the hole is not limited to the above-mentioned first to third embodiments. For example, the hole may be a polygon or a shape obtained by combining a curve and a straight line.

[0085] The plurality of holes are preferably arranged in the circumferential direction, but may be provided at different positions in the radial direction.

[0086] The plurality of holes may not all have the same shape and size, and may include holes of different shapes and sizes.

[0087] (Way)

[0088] The following aspects are disclosed in this specification.

[0089] The rotor (3) of the first embodiment comprises a rotor core (9), a plurality of permanent magnets (11), and a rotating shaft. The rotor core (9) has a plurality of magnet arrangement holes (13) arranged along a circumferential direction (C1). The plurality of permanent magnets (11) are respectively arranged in the plurality of magnet arrangement holes (13). The rotating shaft is fixed to the rotor core (9) with the axis (14) as the center of rotation. The plurality of permanent magnets (11) respectively have an inner end face (26), an outer end face (25), and a pair of side faces (23, 24). The inner end face (26) faces the axis (14) of the rotating shaft (10) on a plane having a straight line consistent with the axis (14) of the rotating shaft (10) as a normal line. The outer end face (25) faces the direction opposite to the axis (14) of the rotating shaft (10) on a plane having a straight line consistent with the axis (14) of the rotating shaft (10) as a normal line. A pair of side surfaces (23, 24) protrude circumferentially relative to an imaginary plane (32) connecting the circumferential edge of the inner end surface (26) and the circumferential edge of the outer end surface (25). The pair of side surfaces (23, 24) are pole surfaces, and the pole surfaces of the same poles of two permanent magnets (11) adjacent in the circumferential direction (C1) among the plurality of permanent magnets (11) are arranged opposite to each other in the circumferential direction (C1). The circumferential length (L1) of the outer end surface (25) is shorter than the circumferential length (L2) of the inner end surface (26). In the rotor core (9), a plurality of holes (41, 42, 41A, 42A, 41B, 42B, 43B, 44B) are provided between the permanent magnets adjacent in the circumferential direction (C1) among the plurality of permanent magnets (11).

[0090] According to this method, since a pair of side surfaces (23, 24) protrude circumferentially outward, the effective area of ​​the magnetic pole surface of the permanent magnet (11) is larger, so that the magnetic flux is larger, and thus the average torque of the motor (1) is higher. Furthermore, the further radially outward, the more the normal of the pair of side surfaces (23, 24) is directed radially outward. As a result, the magnetic flux coming out of the portion of the pair of side surfaces (23, 24) on the side opposite to the side where the axis (14) is located tends to be directed to the side opposite to the axis (14). Therefore, the torque of the motor (1) can be further improved. Furthermore, by providing a plurality of holes (41, 42, 41A, 42A, 41B, 42B, 43B, 44B), the location of the flow of the magnetic flux can be adjusted. As a result of the above, the torque pulsation can be reduced while maintaining the average torque.

[0091] For the rotor (3) of the second embodiment, based on the first embodiment, multiple holes (41, 42, 41A, 42A, 41B, 42B, 43B, 44B) are symmetrically arranged about the magnetic pole center line (31) between the permanent magnets adjacent in the circumferential direction of the multiple permanent magnets (11).

[0092] According to this embodiment, the paths of the magnetic flux formed by the plurality of holes (41, 42, 41A, 42A, 41B, 42B, 43B, 44B) are symmetrical about the magnetic pole center line (31), so that the torque pulsation can be reduced.

[0093] For the rotor (3) of the third embodiment, based on the first embodiment or the second embodiment, the plurality of holes (41, 42, 41A, 42A, 41B, 42B, 43B, 44B) are arranged at a position where the magnetic flux density between the plurality of holes (41, 42, 41A, 42A, 41B, 42B, 43B, 44B) when no load is less than ±40% of the magnetic flux density between one of the plurality of permanent magnets (11) and the hole closest to the permanent magnet (11) when no load is applied.

[0094] According to this aspect, since the difference in magnetic flux density in the path of the magnetic flux formed by the plurality of holes ( 41 , 42 , 41A, 42A, 41B, 42B, 43B, 44B) is small, the torque ripple can be reduced.

[0095] For a rotor (3) of a fourth embodiment, based on any one of the first to third embodiments, a plurality of holes (41, 42, 41A, 42A, 41B, 42B, 43B, 44B) are provided in an area farther from the center of the rotor core (9) when viewed from the axis (14) within the rotor core (9).

[0096] According to this embodiment, the plurality of holes (41, 42, 41A, 42A, 41B, 42B, 43B, 44B) are provided at positions away from the axis, so that the flow of magnetic flux near the stator (2) can be adjusted, thereby reducing torque pulsation.

[0097] A rotor (3) according to a fifth aspect is a rotor according to any one of the first to fourth aspects, wherein the plurality of holes (41, 42, 41A, 42A, 41B, 42B, 43B, 44B) are through holes extending along the axial direction of the rotating shaft (10).

[0098] According to this aspect, since the plurality of holes ( 41 , 42 , 41A, 42A, 41B, 42B, 43B, 44B) penetrate in the axial direction, the effect of making the magnetic resistance different from the surroundings is enhanced, and as a result, the torque ripple can be reduced.

[0099] A sixth aspect of the rotor (3) is the rotor according to any one of the first to fifth aspects, wherein each of the pair of side surfaces (23, 24) has a curved surface or a combination of a curved surface and a flat surface.

[0100] According to this embodiment, the volume of the permanent magnet (11) and the orientation of the side surfaces can be appropriately set by adjusting the shape of the pair of side surfaces, and as a result, the torque ripple can be reduced while maintaining the average torque.

[0101] For the rotor (3) of the seventh embodiment, based on the sixth embodiment, a pair of side surfaces (23, 24) respectively have curved surfaces (23A, 24A) protruding outward in the circumferential direction, and flat surfaces (23B, 24B) arranged on the axis (14) side of the curved surfaces (23A, 24A).

[0102] According to this method, since a pair of side surfaces (23, 24) have planes (23B, 24B) respectively, the portions of the side surfaces (23, 24) on the axis (14) side can be brought closer to each other in the circumferential direction (C1), resulting in an increase in the volume of the permanent magnet (11).

[0103] The rotor (3) of the eighth aspect is based on the seventh aspect, wherein the planes (23B, 24B) are parallel to the magnetic pole center lines (31) between the plurality of permanent magnets (11) when viewed along the axial direction of the rotation shaft (10).

[0104] According to this method, since the planes (23B, 24B) of a pair of side surfaces (23, 24) are parallel to the magnetic pole center line (31), the portions of the side surfaces (23, 24) on the axis (14) side can be brought closer to each other in the circumferential direction (C1), resulting in an increase in the volume of the permanent magnet (11).

[0105] An electric motor (1) according to a ninth aspect includes a rotor (3) according to any one of the first to eighth aspects, and a stator (2).

[0106] According to this aspect, the torque ripple can be reduced while maintaining the average torque.

[0107] Industrial Applicability

[0108] According to the rotor and the motor of the present invention, it is possible to reduce torque ripple while maintaining average torque. Therefore, the rotor and the motor of the present invention are industrially useful.

[0109] Description of Reference Numerals

[0110] 1. Electric motor; 2. Stator; 3. Rotor; 9. Rotor core; 10. Rotating shaft; 11. Permanent magnet; 13. Magnet arrangement hole; 14. Axis; 23. First circumferential end face (side face); 23A. First curved surface; 23B. First plane; 24. Second circumferential end face (side face); 24A. Second curved surface; 24B. Second plane; 25. Outer end face; 26. Inner end face; 31. Magnetic pole center line; 32. Imaginary plane; 41. 41A. 41B. 42. 42A. 42B. 43B. 44B. Hole; C1. Circumferential direction.

Claims

1. A rotor, wherein: The rotor has: A rotor core having a plurality of magnet arrangement holes arranged in a circumferential direction; a plurality of permanent magnets, the plurality of permanent magnets being respectively disposed in the plurality of magnet disposition holes; and A rotating shaft is fixed to the rotor core and has the shaft center as the rotation center. The plurality of permanent magnets respectively have: an inner end surface facing the axis of the rotating shaft; an outer end surface facing in a direction opposite to the axis of the rotation axis; and a pair of side surfaces, the pair of side surfaces protruding in the circumferential direction relative to an imaginary plane connecting the circumferential edge of the inner end surface and the circumferential edge of the outer end surface, respectively; The pair of side surfaces are magnetic pole surfaces, and magnetic pole surfaces of the same poles of two permanent magnets adjacent to each other in the circumferential direction among the plurality of permanent magnets are arranged to face each other in the circumferential direction. The circumferential length of the outer end surface is shorter than the circumferential length of the inner end surface, The rotor core is provided with a plurality of holes between the plurality of permanent magnets adjacent to each other in the circumferential direction.

2. The rotor according to claim 1, wherein: The plurality of holes are symmetrically arranged with respect to a magnetic pole center line between permanent magnets adjacent in the circumferential direction.

3. The rotor according to claim 1 or 2, wherein: The plurality of holes are provided at positions where a magnetic flux density between the plurality of holes when no load is less than ±40% of a magnetic flux density between one of the circumferentially adjacent permanent magnets and the hole closest to the one permanent magnet when no load is applied.

4. The rotor according to claim 1 or 2, wherein: The plurality of holes are provided in the rotor core at positions farther from the center of the rotor core when viewed from the axis.

5. The rotor according to claim 1 or 2, wherein: The plurality of holes are through holes extending along the axial direction of the rotating shaft.

6. The rotor according to claim 1 or 2, wherein: The pair of side surfaces each have a curved surface, or a combination of a curved surface and a flat surface.

7. The rotor according to claim 6, wherein: The pair of side surfaces each have a curved surface convex in the circumferential direction and a flat surface disposed on the axial center side of the curved surface.

8. The rotor according to claim 7, wherein: The plane is parallel to a magnetic pole center line between permanent magnets adjacent to each other in the circumferential direction when viewed along the axial direction of the rotation axis.

9. An electric motor, wherein: The motor has: The rotor according to any one of claims 1 to 8; and stator.

Images