Rotor and electric motor

Abstract

The rotor includes: a rotor core having a plurality of first holes and a plurality of second holes; and a plurality of first permanent magnets respectively arranged in the plurality of first holes, the plurality of first holes and the plurality of second holes being arranged radially about a rotational axis, the plurality of first holes each extending along a radial direction of the rotor core, each of the plurality of second holes having a length in the radial direction of the rotor core that is smaller than a length of each of the plurality of first holes in the radial direction of the rotor core, and each of the plurality of second holes having a protruding portion that is located on an inner side in the radial direction of the rotor core with respect to a first hole of the plurality of first holes that is adjacent to the second hole in a circumferential direction of the rotor core and protrudes toward the first hole of the plurality of first holes that is adjacent to the second hole in the circumferential direction of the rotor core.

Description

Technical Field

[0001] This disclosure relates to rotors and electric motors having rotors. In particular, this disclosure relates to a permanent magnet-embedded rotor having permanent magnets disposed in its core and an electric motor having such a rotor. Background Technology

[0002] Electric motors are used in a wide variety of electrical devices, including household and industrial equipment. Among electric motors, the IPM (Interior Permanent Magnet) motor is known, which has a rotor with permanent magnets embedded in an iron core. In an IPM motor, in addition to the magnetic torque generated by the permanent magnets embedded in the iron core, a reluctance torque is also obtained due to the unevenness in the magnitude of the magnetic reluctance generated in the iron core. Therefore, small and efficient motors can be realized.

[0003] Conventionally, as a rotor for an IPM motor, there is a known IPM rotor having: an iron core having a plurality of first magnet mounting holes and second magnet mounting holes alternately arranged in the circumferential direction; a first permanent magnet disposed in the first magnet mounting holes with the direction of its magnetic poles in the circumferential direction of the iron core; and a second permanent magnet disposed in the second magnet mounting holes with the direction of its magnetic poles in the radial direction of the iron core (e.g., Patent Document 1).

[0004] However, in conventional IPM-type rotors, the area of ​​the iron core through which the magnetic flux of the first permanent magnet can pass is smaller than that of the second permanent magnet. As a result, the magnetic flux of the second magnet's mounting hole interferes with that of the first permanent magnet, leading to a problem of reduced linkage magnetic flux with the stator.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Application Publication No. 8-275419 Summary of the Invention

[0008] This disclosure was made to solve such a problem, and its purpose is to provide a rotor and motor capable of increasing the linkage flux.

[0009] To achieve the above objectives, a rotor solution disclosed herein includes: an iron core having a plurality of first holes and a plurality of second holes; a plurality of first permanent magnets respectively disposed in the plurality of first holes; and a rotating shaft fixed to the iron core, wherein the plurality of first holes and the plurality of second holes are arranged radially about the rotating shaft, the plurality of first holes extend radially along the iron core, the radial length of each of the plurality of second holes in the iron core is smaller than the radial length of each of the plurality of first holes in the iron core, and each of the plurality of second holes has a protrusion located radially inside the iron core relative to the first hole adjacent to the second hole in the circumferential direction of the iron core and protruding toward the first hole adjacent to the second hole in the circumferential direction of the iron core.

[0010] Furthermore, one technical solution of the electric motor disclosed herein includes: a rotor as described above; and a stator, which is disposed opposite to the rotor through an air gap to generate a magnetic force acting on the rotor.

[0011] According to this disclosure, it is possible to increase the linkage magnetic flux. Attached Figure Description

[0012] Figure 1 This is a perspective view of the electric motor in the implementation method.

[0013] Figure 2 This is a cross-sectional view of the electric motor according to the embodiment.

[0014] Figure 3 This is a cross-sectional view of the rotor in the embodiment.

[0015] Figure 4 This is a diagram showing an enlarged top view of a portion of the rotor in the embodiment and a cross-sectional view at line AA of the enlarged top view.

[0016] Figure 5 This is an enlarged top view showing a portion of the rotor of Comparative Example 1.

[0017] Figure 6 This is an enlarged top view showing a portion of the rotor of Comparative Example 2.

[0018] Figure 7 This is an enlarged top view showing a portion of the rotor in the embodiment.

[0019] Figure 8 This is an enlarged top view showing a portion of the rotor of Modified Example 1.

[0020] Figure 9 This is an enlarged top view showing a portion of the rotor of Modified Example 2.

[0021] Figure 10 This is an enlarged top view showing a portion of the rotor of Modified Example 3.

[0022] Figure 11 This is an enlarged top view showing a portion of the rotor of modified example 4.

[0023] Figure 12 This is an enlarged top view showing a portion of the rotor of Modified Example 5.

[0024] Figure 13 This is an enlarged top view showing a portion of the rotor of modified Example 6.

[0025] Figure 14 This is a partial sectional view of the rotor of variant example 7.

[0026] Figure 15 This is a partial sectional view of the rotor of variant example 8.

[0027] Figure 16 This is a partial sectional view of the rotor of variant example 9.

[0028] Figure 17 This is an enlarged top view showing a portion of the rotor of modified example 10.

[0029] Figure 18 This is an enlarged top view showing a portion of the rotor of modified Example 11.

[0030] Figure 19 This is an enlarged top view showing a portion of the rotor of modified example 12.

[0031] Figure 20 This is an enlarged top view showing a portion of the rotor of modified example 13.

[0032] Figure 21 This is a partial sectional view of the stator of the electric motor in variation 14.

[0033] Figure 22 This is a cross-sectional view of the rotor of variant example 15. Detailed Implementation

[0034] The following describes embodiments of this disclosure. Furthermore, the embodiments described below represent specific examples of this disclosure. Therefore, the numerical values, constituent elements, arrangement and connection patterns of constituent elements, and processes and their order shown in the following embodiments are examples and are not intended to limit this disclosure. Consequently, any constituent elements in the following embodiments not described in the independent claims representing the highest-level concept of this disclosure will be described as arbitrary constituent elements.

[0035] Furthermore, the figures are schematic diagrams and not necessarily precise representations. Additionally, substantially identical structures are labeled with the same reference numerals across the figures, and repetitive descriptions are omitted or simplified.

[0036] (Implementation Method)

[0037] First, use Figure 1 and Figure 2 The outline structure of the electric motor 1 in the embodiment is explained. Figure 1 This is a perspective view of the electric motor 1 according to the embodiment. Figure 2 This is a cross-sectional view of the motor 1. Additionally, Figure 2 This represents the cross section when cut by a plane orthogonal to the axis of rotation 10.

[0038] like Figure 1 and Figure 2 As shown, the electric motor 1 includes a rotor 2 and a stator 3. The electric motor 1 is an inner rotor type motor in which the rotor 2 is disposed inside the stator 3. That is, the stator 3 is configured to surround the rotor 2.

[0039] The rotor 2 rotates under the influence of the magnetic force generated by the stator 3. Specifically, the rotor 2 has a rotation shaft 10 and rotates about the axis C of the rotation shaft 10 as the center of rotation.

[0040] Rotor 2 generates a magnetic force that acts on stator 3. Rotor 2 has a structure in which multiple N poles and S poles, which serve as the main magnetic flux, are repeatedly present in the circumferential direction. The direction of the main magnetic flux generated by rotor 2 is orthogonal to the direction of the axis C of the rotating shaft 10 (the direction of the rotating axis).

[0041] The rotor 2 and stator 3 are separated by an air gap. Specifically, there is a small air gap between the surface of the rotor 2 and the surface of the stator 3. The rotor 2 is a permanent magnet embedded type rotor (IPM rotor) with permanent magnets embedded in the iron core, as detailed later. Therefore, the electric motor 1 of this embodiment is an IPM motor.

[0042] The stator 3 is positioned opposite the rotor 2 across an air gap, generating a magnetic force acting on the rotor 2. Specifically, the stator 3 is configured to surround the rotor core 20 of the rotor 2. The stator 3 and the rotor 2 together form a magnetic circuit.

[0043] The stator 3 is constructed with N poles and S poles alternately formed in the circumferential direction on the air gap surface as the main magnetic flux. The stator 3 has a stator core 3a and a stator coil 3b.

[0044] The stator core 3a is provided with a plurality of teeth 3a1 protruding toward the rotor core 20 of the rotor 2. Specifically, the plurality of teeth 3a1 are arranged such that they protrude toward the axis C of the rotation shaft 10. Furthermore, the plurality of teeth 3a1 are arranged at equal intervals in the circumferential direction. Thus, the plurality of teeth 3a1 extend radially in a direction orthogonal to the axis C of the rotation shaft 10.

[0045] The stator core 3a is, for example, composed of multiple steel plates stacked in the direction of the axis C of the rotation shaft 10. Each of the multiple steel plates is, for example, an electromagnetic steel plate punched into a predetermined shape. Alternatively, the stator core 3a is not limited to a stack of multiple steel plates, but can also be a block made of magnetic material.

[0046] The winding coil 3b is wound around each of the multiple teeth 3a1 of the stator core 3a. Specifically, the winding coil 3b is wound around each tooth 3a1 through an insulator. Each winding coil 3b is composed of a unit coil of each of the three phases: U-phase, V-phase, and W-phase, which are electrically phased by 120 degrees. That is to say, the winding coil 3b wound around each tooth 3a1 is driven by the alternating current of the three phases, with each phase (U-phase, V-phase, and W-phase) energized separately. Thus, the main magnetic flux of the stator 3 is formed in each tooth 3a1.

[0047] In the electric motor 1 configured in this way, when energized to the winding coil 3b of the stator 3, the magnetic field current flows to the winding coil 3b and forms a magnetic flux in the stator 3. The magnetic force generated by the interaction between the magnetic flux of the stator 3 and the magnetic flux of the rotor 2 becomes the torque that makes the rotor 2 rotate.

[0048] Next, refer to Figure 1 and Figure 2 Use Figure 3 and Figure 4 This section describes the detailed structure of rotor 2 in this embodiment. Figure 3 This is a cross-sectional view of rotor 2 in the embodiment. Figure 4 This is an enlarged top view of a portion of the rotor 2 and a cross-sectional view along line AA of the enlarged top view. Additionally, Figure 3 This represents the cross section when cut by a plane orthogonal to the axis of rotation 10.

[0049] like Figures 1-3 As shown, the rotor 2 includes a rotating shaft 10, a rotor core 20, a plurality of first permanent magnets 30 and a plurality of second permanent magnets 40.

[0050] The rotating shaft 10 is an elongated shaft that serves as the center of rotation of the rotor 2. The rotating shaft 10 is, for example, a metal rod, fixed to the center of the rotor 2. Specifically, the rotating shaft 10 is fixed to the rotor core 20, protruding to both sides of the rotor 2, and passing through the center of the rotor core 20. The rotating shaft 10 is fixed to the rotor core 20 by pressing or heat-fitting it into a through hole 20a formed in the center of the rotor core 20.

[0051] Furthermore, although not shown in the figure, a first portion of the rotating shaft 10 protruding towards one side of the rotor 2 is supported by a first bearing, and a second portion of the rotating shaft 10 protruding towards the other side of the rotor 2 is supported by a second bearing. Additionally, a load driven by the electric motor 1 is mounted at either the first or second portion of the rotating shaft 10.

[0052] The rotor core 20 is a core with multiple first holes 21 and multiple second holes 22. For example... Figure 4 As shown, the rotor core 20 is composed of multiple steel plates 20b stacked in the direction of the axis C of the rotating shaft 10. Specifically, the rotor core 20 is a substantially cylindrical stack of multiple steel plates 20b stacked in the direction of the axis C of the rotating shaft 10. The multiple steel plates 20b are, for example, electromagnetic steel plates stamped into a predetermined shape and fixed to each other by riveting or the like.

[0053] like Figure 3 As shown, a plurality of first holes 21 and a plurality of second holes 22 are arranged radially around the rotation shaft 10. Here, "radial" includes a physically radial arrangement, but also includes arrangements that are offset due to manufacturing errors. The plurality of first holes 21 are arranged at equal intervals along the circumference of the rotor core 20 (the direction of rotation of the rotation shaft 10). Similarly, the plurality of second holes 22 are also arranged at equal intervals along the circumference of the rotor core 20. The first holes 21 and second holes 22 are arranged alternately along the circumference. Figure 4 As shown, the first hole 21 and the second hole 22 are through holes that penetrate the rotor core 20 along the axis C of the rotation shaft 10. Furthermore, in any cross-section cut with a plane orthogonal to the rotation shaft 10, the cross-sectional shape of each of the first holes 21 is the same along the axis C of the rotation shaft 10, and the cross-sectional shape of each of the second holes 22 is the same along the axis C of the rotation shaft 10. Therefore, the same shape of the first hole 21 and the same shape of the second hole 22 are formed in all the steel plates 20b constituting the rotor core 20.

[0054] like Figure 3As shown, in top view, multiple first holes 21 extend radially along the rotor core 20 (in a direction orthogonal to the axis C of the rotation shaft 10). Therefore, the multiple elongated first holes 21 are formed in a spoke-like shape with the rotation shaft 10 as the center. The top view shape of each first hole 21 is a rectangle with the radial direction of the rotor core 20 as its length. The top view shape of each of the multiple first holes 21 is the same as that of the other first holes 21.

[0055] On the other hand, when viewed from above, the radial length of the rotor core 20 of each of the plurality of second holes 22 is smaller than the length of the first hole 21. That is, the radial length of the rotor core 20 of each of the plurality of second holes 22 is shorter than the radial length of the rotor core 20 of each of the plurality of first holes 21. In this embodiment, the radial length of the rotor core 20 of the second hole 22 is less than half the radial length of the rotor core 20 of the first hole 21. The top view shape of each of the plurality of second holes 22 is the same as that of the other second holes 22. Furthermore, the specific top view shape of the second hole 22 will be described later.

[0056] Multiple first permanent magnets 30 are respectively disposed in multiple first holes 21. That is, the first hole 21 is a first magnet placement hole in which the first permanent magnet 30 is disposed. The first permanent magnet 30 is a sintered magnet. Therefore, the first hole 21 is a magnet insertion hole into which the first permanent magnet 30, as a sintered magnet, is inserted. One first permanent magnet 30 is inserted into one first hole 21.

[0057] The first permanent magnet 30 is the main magnet of the rotor 2. Specifically, the first permanent magnet 30 is configured such that the direction of its magnetic poles is circumferential to that of the rotor core 20 (the direction of rotation of the rotating shaft 10). That is, the first permanent magnet 30 is magnetized such that the direction of its magnetic poles is circumferential to that of the rotor core 20. In addition, the directions of the S pole and N pole of two adjacent first permanent magnets 30 are opposite.

[0058] The top view shape and size of the first permanent magnet 30 are approximately the same as those of the first hole 21. The first permanent magnet 30 is fitted into the first hole 21. Therefore, the top view shape of the first permanent magnet 30 is a long rectangle. As an example, the first permanent magnet 30 is a plate-shaped cuboid.

[0059] Additionally, a small clearance may exist between the first permanent magnet 30 and the inner surface of the first hole 21 in each of the first holes 21. An adhesive material for bonding and fixing the first permanent magnet 30 to the first hole 21 may be provided in this clearance. Alternatively, no adhesive material may be provided in this clearance. The clearance between the first permanent magnet 30 and the inner surface of the first hole 21 should be manufactured to the minimum necessary dimensional tolerances.

[0060] Furthermore, multiple second permanent magnets 40 are respectively disposed in multiple second holes 22. That is, the second hole 22 is a second magnet placement hole in which the second permanent magnet 40 is disposed. The second permanent magnet 40 is a sintered magnet. Therefore, the second hole 22 is a magnet insertion hole into which the second permanent magnet 40, as a sintered magnet, is inserted. One second permanent magnet 40 is inserted into one second hole 22.

[0061] The second permanent magnet 40 is an auxiliary magnet for the rotor 2. Specifically, the second permanent magnet 40 is arranged such that the direction of its magnetic poles is radial to the rotor core 20 (orthogonal to the rotation axis 10). That is, the second permanent magnet 40 is magnetized such that the direction of its magnetic poles is radial to the rotor core 20. In addition, the directions of the S pole and N pole of two adjacent second permanent magnets 40 are opposite.

[0062] The top view shape of the second permanent magnet 40 differs from that of the second hole 22. The top view shape of the second permanent magnet 40 is a rectangle with a small aspect ratio. As an example, the second permanent magnet 40 is a rod-shaped cuboid.

[0063] Each of the plurality of second holes 22 has a protrusion 22a. In each second hole 22, the protrusion 22a is located on the radially inner side of the rotor core 20 with respect to the first hole 21 that is adjacent to the second hole 22 in the circumferential direction of the rotor core 20, and protrudes toward the first hole 21 that is adjacent to the second hole 22 in the circumferential direction of the rotor core 20.

[0064] The top view shape of each second hole 22 is formed by adding a protrusion 22a to the same shape as the top view shape of the second permanent magnet 40. That is, the top view shape of each second hole 22 is formed by adding a protrusion 22a to the side of a rectangle with a small aspect ratio.

[0065] In each of the plurality of second holes 22, the protrusion 22a is located on the radially inner side of the rotor core 20. That is, the protrusion 22a does not protrude entirely from one side of the rectangular portion of the second hole 22, but rather protrudes partially from the inner side of one side of the rectangular portion of the second hole 22.

[0066] In each of the second holes 22, the top view shape of the protrusion 22a is a shape having a vertex and narrowing in width towards the vertex. Furthermore, in each of the second holes 22, the protrusion 22a has an opposing side that faces one side of the first hole 21 adjacent to that second hole 22. Preferably, the angle formed by the opposing side and one side of the adjacent first hole 21 is -5° or more and 5° or less. In this embodiment, the opposing side of the protrusion 22a is parallel to one side of the first hole 21 adjacent to that protrusion 22a. Specifically, the top view shape of the protrusion 22a is triangular, and one side of this triangle is parallel to one side of the first hole 21. Thus, as... Figure 4 As shown, the width of the bridge portion 20br, which is the part between the protrusion 22a and the first hole 21, is constant.

[0067] In each of the plurality of second holes 22, a protrusion 22a is provided on both sides of the second hole 22, separated from the center line extending radially in the rotor core 20. That is, the protrusion 22a protrudes from the two opposite sides of the rectangular portion of the second hole 22. Thus, the top view shape of the second hole 22 is a shape formed by combining the top view shape of the second permanent magnet 40, i.e., a rectangle with a smaller aspect ratio, and a triangle that protrudes partially from the inner side of each of the two opposite sides of the rectangle.

[0068] Furthermore, in each of the plurality of second holes 22, two protrusions 22a are arranged symmetrically with respect to the center line of the second hole 22 extending radially along the rotor core 20.

[0069] The second permanent magnet 40, disposed in the second hole 22, is located in the rectangular portion of the second hole 22. Therefore, in each second hole 22, the protrusion 22a is not occupied by the second permanent magnet 40 and remains as a gap. That is, the second permanent magnet 40 is not present in the protrusion 22a, and the protrusion 22a becomes a gap (spatial region).

[0070] Furthermore, in each rectangular portion of the second hole 22, a small clearance may exist between the second permanent magnet 40 and the inner surface of the second hole 22. An adhesive material for bonding and fixing the second permanent magnet 40 to the second hole 22 may be provided in this clearance. In this case, adhesive material for fixing the second hole 22 and the second permanent magnet 40 may also be present at least partially on the protrusion 22a. In each rectangular portion of the second hole 22, no adhesive material may be provided in the clearance between the second permanent magnet 40 and the inner surface of the second hole 22. That is, in each rectangular portion of the second hole 22, the clearance between the second permanent magnet 40 and the inner surface of the second hole 22 may be maintained within the minimum necessary dimensional tolerances during manufacturing.

[0071] The rotor 2 thus constructed is an 8-pole rotor with 8 magnetic poles. It has 8 first permanent magnets 30 and 8 second permanent magnets 40 arranged circumferentially, with the S pole and N pole existing alternately in the circumferential direction as the main magnetic flux. That is, the rotor core 20 has 8 first holes 21 and 8 second holes 22 alternately provided.

[0072] Next, use Figures 5-7 This also includes the effects of the rotor 2 and motor 1 in this embodiment as described in the disclosure. Figure 5 This is an enlarged top view showing a portion of the rotor 2X of Comparative Example 1. Figure 6 This is an enlarged top view showing a portion of the rotor 2Y of Comparative Example 2. Figure 7 This is an enlarged top view showing a portion of the rotor 2 in the embodiment. Additionally, in Figures 5-7 In the image, the arrows represent the flow of magnetic flux.

[0073] like Figure 5 As shown, in the rotor 2X of Comparative Example 1, similar to the rotor 2 of the above embodiment, a first hole 21 and a second hole 22X are provided in the rotor core 20X. In the rotor 2X, a first permanent magnet 30 is disposed in the first hole 21 and a second permanent magnet 40X is disposed in the second hole 22X.

[0074] However, the rotor 2X of Comparative Example 1 differs from the rotor 2 of the above embodiment. The top view shape of the second hole 22X and the second permanent magnet 40X is trapezoidal, and the entire side of the second hole 22X (the opposite side opposite to the first hole 21) is parallel to the side of the first hole 21. Therefore, in Figure 5 In the construction of rotor 2X of Comparative Example 1 shown, at the corner portion of the base of the trapezoid of the second hole 22X ( Figure 5 (The part shown by the dashed circle) is where the flow of magnetic flux is impeded.

[0075] like Figure 6 As shown, in the rotor 2Y of Comparative Example 2, similar to the rotor 2 of the above embodiment, a first hole 21 and a second hole 22Y are provided in the rotor core 20Y. A first permanent magnet 30 is disposed in the first hole 21 and a second permanent magnet 40Y is disposed in the second hole 22Y.

[0076] However, the rotor 2Y of Comparative Example 2 differs from the rotor 2 of the above embodiment; the top view shape of the second hole 22Y and the second permanent magnet 40Y is rectangular. Therefore, in Figure 6 In the rotor 2Y of Comparative Example 2 shown, the radially outer portion of the side surface of the second hole 22Y (the opposite side to the first hole 21) is significantly separated from the side surface of the first hole 22. As a result, in the construction of the rotor 2Y of Comparative Example 2, the leakage flux ( Figure 6The dashed arrow (indicated by the increase in the distance) indicates this. Therefore, in the adjacent first permanent magnet 30 and second permanent magnet 40Y, the magnetic flux of the first permanent magnet 30 interferes with the magnetic flux of the second permanent magnet 40Y. Specifically, the magnetic flux of the second permanent magnet 40Y interferes with the magnetic flux of the first permanent magnet 30 adjacent to it. Consequently, the linkage magnetic flux with the stator decreases.

[0077] In contrast, in rotor 2 of this embodiment, as Figure 7 As shown, each of the plurality of second holes 22 has a protrusion 22a, which is located on the radially inner side of the rotor core 20 with respect to the first hole 21 that is adjacent to the second hole 22 in the circumferential direction of the rotor core 20 and protrudes toward the first hole 21 that is adjacent to the second hole 22 in the circumferential direction of the rotor core 20.

[0078] According to this structure, the width between the second hole 22 and the first hole 21 can be increased at a position radially outward of the rotor core 20 of the second hole 22, and the width between the second hole 22 and the first hole 21 can be narrowed at a position radially inward of the second hole 22 of the rotor core 20. In other words, the width of the bridge portion 20br, which forms the portion between the second hole 22 (protrusion 22a) and the first hole 21, can be narrowed only at a position radially inward of the second hole 22 of the rotor core 20. Therefore, it is possible to suppress [the following]... Figure 5 Unlike the rotor 2X in Comparative Example 1, where the shape of the second hole 22X obstructs the flow of magnetic flux, it can suppress situations like... Figure 6 In Comparative Example 2, the magnetic flux of the first permanent magnet 30 interferes with the magnetic flux of the second permanent magnet 40Y, resulting in a decrease in the magnetic flux linked with the stator, as in the rotor 2Y.

[0079] Based on the above, the rotor 2 according to this embodiment can reduce leakage flux and increase linkage flux with stator 3.

[0080] Furthermore, in the rotor 2 of this embodiment, the opposite side of the protrusion 22a of the second hole 22, which is opposite to the first hole 21, can be parallel to the side surface of the first permanent magnet 30 and the first hole 21. That is, the width of the bridge portion 20br can be constant.

[0081] Based on this structure, leakage flux can be further reduced. Therefore, the flux linked with stator 3 can be further increased.

[0082] In this case, the top view shape of the protrusion 22a can be a shape with a vertex and a width that narrows towards the vertex.

[0083] According to this structure, it is easy to make the opposite side of the protrusion 22a of the second hole 22, which is opposite to the first hole 21, parallel to the side surface of the first permanent magnet 30 and the first hole 21. That is, it is easy to make the width of the bridge portion 20br constant.

[0084] Here, the length l of the portion of the bridge portion 20br, which is the part between the second hole 22 (protrusion 22a) and the first hole 21, opposite to the portion of the first permanent magnet 30, is investigated. Figure 7 This explains the results of their research.

[0085] like Figure 7 As shown, when the length of the portion of the protrusion 22a in the bridge portion 20br that is opposite to the first permanent magnet 30 is set to l, l becomes the distance between the inner circumferential end face of the first permanent magnet 30 and point P. Here, point P is the outer end of the projected image when the protrusion 22a is projected onto the opposite side from the direction perpendicular to the opposite side of the first hole 21 opposite to the second hole 22.

[0086] The region in the first permanent magnet 30 that generates short-circuit magnetic flux ( Figure 7 The area shown in the shaded area is designated as region S. The radial length of the rotor core 20 at region S is set as l. mg Let the surface magnetic flux density of the first permanent magnet 30 be B'. r At that time, the magnetic flux φ1 generated in region S is expressed as φ1=B' r ×l mg .

[0087] Furthermore, the magnetic flux density of MS in the magnetic saturation region of the bridge section 20br is set to B'. s When the width of the inner circumferential end face of the first permanent magnet 30 of the bridge section 20br is set as w, the magnetic flux φ2 through the magnetic saturation region MS is expressed as φ2=B' s ×w.

[0088] At this time, when the magnetic flux that is short-circuited outside the magnetic saturation region MS is set as A (A>0), it can be expressed as φ1=φ2+A, which becomes the following (Equation 1).

[0089] [Mathematical Expression 1]

[0090] …(Formula 1)

[0091] Preferably, the length l of the portion of the protrusion 22a of the bridge portion 20br that is opposite to the first permanent magnet 30 is equal to the radial length l of the rotor core 20 at the region S in the first permanent magnet 30 where short-circuit magnetic flux is generated. mg The same. Therefore, in the above (Equation 1), when substituting l = l mgAt that time, the length l of the portion of the protrusion 22a of the bridge portion 20br that is opposite to the first permanent magnet 30 can be represented by the following (Equation 2).

[0092] [Mathematical Expression 2]

[0093] …(Equation 2)

[0094] Furthermore, when the residual magnetic flux density of the first permanent magnet 30 is set to B... r Set the saturation magnetization of rotor core 20 to J. s At that time, B' r <Br、B' s >J s Therefore, A > 0, so the above (Equation 2) can be represented by the following (Equation 3).

[0095] [Mathematical Expression 3]

[0096] …(Formula 3)

[0097] Based on the above, the length l of the portion of the protrusion of the bridge section 20br that is opposite to the first permanent magnet can satisfy the relationship in Equation 3 above. By satisfying this relationship in Equation 3, leakage flux can be reduced and the linkage flux linked with the stator can be effectively increased.

[0098] As described above, the rotor 2 of this embodiment includes: a rotor core 20 having a plurality of first holes 21 and a plurality of second holes 22; a plurality of first permanent magnets 30 respectively disposed in the plurality of first holes 21; and a rotating shaft 10 fixed to the rotor core 20. The plurality of first holes 21 and the plurality of second holes 22 are arranged radially about the rotating shaft 10. The plurality of first holes 21 extend radially along the rotor core 20. The radial length of the rotor core 20 of each of the plurality of second holes 22 is smaller than the radial length of the rotor core 20 of each of the plurality of first holes 21. The plurality of second holes 22 each have a protrusion 22a located radially inside the first hole 21 that is adjacent to the second hole 22 in the circumferential direction of the rotor core 20 and protruding toward the first hole 21 that is adjacent to the second hole 22 in the circumferential direction of the rotor core 20.

[0099] This increases the linkage flux.

[0100] In the rotor 2, in each of the plurality of second holes 22, the protrusion 22a is located on the radially inner side of the rotor core 20.

[0101] According to this structure, it is possible to increase the linked magnetic flux composed of the magnetic flux of the first permanent magnet 30 and the magnetic flux of the second permanent magnet 40.

[0102] In the rotor 2, in each of the plurality of second holes 22, the protrusion 22a includes two protrusions 22a, which are provided on both sides of the second hole 22, separated by a center line extending radially in the rotor core 20. In this case, the protrusions 22a can be arranged symmetrically with respect to the center line extending radially in the rotor core 20 of the second hole 22.

[0103] According to this structure, leakage flux can be reduced and linkage flux increased when the rotor 2 rotates to the left and right. Furthermore, the protrusion 22a may not be provided on both sides, but only on one side. Additionally, a second hole 22 with a protrusion 22a at one end and a second hole 22 with a protrusion 22a at the other end may be alternately provided in the circumferential direction.

[0104] (Variation example)

[0105] The rotor 2 and motor 1 of this disclosure have been described above based on the embodiments, but this disclosure is not limited to the above embodiments.

[0106] For example, in the above embodiment, a second permanent magnet 40 is disposed in the second hole 22, but it is not limited thereto. Figure 8 This is an enlarged top view showing a portion of the rotor of Modified Example 1. Specifically, it can also be shown as... Figure 8 As shown in rotor 2A, the second permanent magnet 40 is not disposed in the second hole 22, but the first permanent magnet 30 is disposed only in the first hole 21 of the first hole 21 and the second hole 22. That is to say, in Figure 8 In this configuration, each of the multiple second holes 22 lacks a second permanent magnet 40, forming a void (spatial region). In this case, the main magnetic flux of the rotor 2A decreases by an amount corresponding to the absence of the second permanent magnet 40, but compared to... Figure 8 Compared to the case where no protrusion 22a is provided in the second hole 22, leakage flux can be reduced and linkage flux can be increased.

[0107] In the above embodiment, the bridge portion 20br is flush with other parts of the rotor core 20, but is not limited thereto. Figure 9 This is an enlarged top view showing a portion of the rotor of Modified Example 2. Specifically, it can also be shown as... Figure 9 As shown in rotor 2B, the surface of the bridge portion 20br of rotor core 20B is recessed in the direction of the axis C of rotation shaft 10. For example, a recess 23 can be formed in the bridge portion 20br by performing a pressing process on rotor core 20B. Figure 9 The area shown by the shaded dots in the top view makes the surface of the bridge section 20br concave compared to other surfaces. Therefore, the thickness t of the bridge section 20br... pressThe thickness t can be thinner than the portion other than the bridge portion 20br. In this way, by reducing the thickness by recessing the bridge portion 20br, the leakage flux can be further reduced, and the linkage flux can be further increased. In addition, it is not limited to recessing the entire surface of the bridge portion 20br; it can also be configured such that at least a portion of the bridge portion 20br is recessed.

[0108] In the above embodiments, such as Figure 7 As shown, the portion of the protrusion 22a located on the radially inner side closest to the rotor core 20 is near the surface on the inner circumferential side of the first permanent magnet 30, but is not limited thereto. Figure 10 This is an enlarged top view showing a portion of the rotor of modified example 3. Specifically, it can also be shown as... Figure 10 As shown in the rotor core 20C of rotor 2C, the protrusion 22a is partially located on the radially inner side of rotor core 20, which is closer to the inner circumferential side of the first permanent magnet 30.

[0109] In the above embodiment, the top view shape of the protrusion 22a of the second hole 22 is a polygon consisting only of straight sides, and the side of the protrusion 22a is consisting only of a plane, but is not limited thereto. Figure 11 This is an enlarged top view showing a portion of the rotor in modified example 4. For example, it could also be as follows: Figure 11 As shown in the rotor 2D, the rotor core 20D has a curved surface on one of the sides of the protrusion 22a. In this case, as in the embodiment described above, the side of the protrusion 22a opposite to the first hole 21 can be made flat, and the side of the protrusion 22a opposite to the first hole 21 is parallel to the side of the first hole 21. That is, when viewed from above, the opposite edge of the protrusion 22a opposite to the first hole 21 can be parallel to one side of the first hole 21.

[0110] In the above embodiment, the opposite side of the protrusion 22a that is opposite to the first hole 21 is parallel to one side of the first hole 21, but it is not limited to this. Figure 12 This is an enlarged top view showing a portion of the rotor in modified example 5. For example, it could also be as follows: Figure 12 As shown in the rotor core 20E of rotor 2E, the opposite side of the protrusion 22a that is opposite to the first hole 21 is not parallel to one side of the first hole 21. Figure 13 This is an enlarged top view showing a portion of the rotor of modified example 6. Similarly, it can also be shown as... Figure 13 As shown in the rotor core 20F of rotor 2F, the opposite side of the protrusion 22a that faces the first hole 21 is not parallel to one side of the first hole 21 of rotor core 20F. For example, it can be as follows: Figure 12 As shown, the protrusion 22a is provided in such a way that the opposite side of the protrusion 22a is away from the first hole 21. Alternatively, it can be provided as shown in the figure. Figure 13As shown, the protrusion 22a is provided with its opposite side close to the first hole 21. Furthermore, although not shown, the opposite side of the protrusion 22a may also be composed of multiple straight lines. Additionally, although not shown, the opposite side of the protrusion 22a may also be composed of multiple curves, or a combination of one or more straight lines and one or more curves.

[0111] Furthermore, in the above embodiments, the cross-sectional shape of each of the second holes 22 is the same in the direction of the axis C of the rotation axis 10 in any cross section when cut with a plane orthogonal to the rotation axis 10, but is not limited thereto.

[0112] Figure 14 This is a partial sectional view of the rotor in variant example 7. For example, it could also be as follows: Figure 14 As shown in the rotor core 20H of rotor 2H, at least two of the plurality of steel plates 20b do not have the second hole 22, while the steel plate 20b located between the two steel plates 20b without the second hole 22 has the second hole 22, and the second permanent magnet 40 is clamped by the two steel plates 20b without the second hole 22. Specifically, in Figure 14 In the rotor core 20H, the steel plates 20b at both ends of the plurality of steel plates 20b do not have the second hole 22, and the second permanent magnet 40 is held by the steel plate 20b at one end and the steel plate 20b at the other end. Thus, the second permanent magnet 40 can be held in the second hole 22 without the use of adhesive material.

[0113] Figure 15 This is a partial sectional view of the rotor in variant example 8. Alternatively, it can be as follows: Figure 15 As shown in the rotor core 20I of rotor 2I, at least one of the plurality of steel plates 20b does not have the second hole 22, and two second permanent magnets 40 are arranged across the steel plate 20b that does not have the second hole 22. Specifically, in Figure 15 In the rotor core 20I, two second permanent magnets 40 are arranged in a second hole 22. According to this structure, multiple second permanent magnets 40 can be easily inserted into a second hole 22. Alternatively, more than three second permanent magnets 40 can be arranged in a second hole 22.

[0114] Figure 16 This is a partial sectional view of the rotor in variant example 9. Alternatively, it can be as follows: Figure 16 Like the rotor core 20J of the rotor 2J shown, at least one of the plurality of steel plates 20b has a protrusion 24 that partially protrudes from the edge of the second hole 22 toward the inside of the second hole 22. Specifically, in Figure 16In the rotor core 20J, a protrusion 24 is provided in the second hole 22 of one of the steel plates 20b located at both ends. According to this structure, when the second permanent magnet 40 is inserted into the second hole 22, the protrusion 24 functions as a stop, thus easily holding the second permanent magnet 40 in the second hole 22. The protrusion 24 is not limited to being formed in all the second holes 22 formed in a rotor core 20J, but may be formed only in a portion of the second holes 22.

[0115] Furthermore, in the above embodiment, the inner peripheral side (rotation axis 10 side) of the second hole 22 and the second permanent magnet 40 is at the same position as the inner peripheral side of the first hole 21 and the first permanent magnet 30, but is not limited to this. Figure 17 This is an enlarged top view showing a portion of the rotor of modified example 10. For example, it can also be as follows: Figure 17 As shown in the rotor core 20K of rotor 2K, the inner circumferential edges of the second hole 22 and the second permanent magnet 40 are located closer to the inner circumferential edge (on the side of the rotation shaft 10) than the inner circumferential edges of the first hole 21 and the first permanent magnet 30. That is, the second hole 22 and the second permanent magnet 40 are located closer to the inner circumferential edge than the first hole 21 and the first permanent magnet 30. Alternatively, although not shown, the inner circumferential edges of the second hole 22 and the second permanent magnet 40 may also be located closer to the outer circumferential edge than the inner circumferential edges of the first hole 21 and the first permanent magnet 30.

[0116] In the above embodiment, no gap is formed in the first hole 21 where the first permanent magnet 30 is inserted, but it is not limited to this. Figure 18 This is an enlarged top view showing a portion of the rotor of modified example 11. For example, it can also be as follows: Figure 18 As shown in the rotor core 20L of rotor 2L, a gap 21a is formed at both ends of the outer periphery of the first hole 21 as a magnetic isolation part. According to this structure, even if torque fluctuation increases as a result of reducing leakage flux by using the first permanent magnet 30 and the second permanent magnet 40 and providing the protrusion 22a in the second hole 22, torque fluctuation can be reduced by forming the gap 21a in the first hole 21.

[0117] In the rotor 2 of the above embodiment, a rotor core 20 with a circular outer peripheral shape when viewed from above is used, but it is not limited to this. Figure 19 This is an enlarged top view showing a portion of the rotor of modified example 12. Specifically, it can also be shown as... Figure 19 As shown in the rotor 2M, a rotor core 20M is used, which has a flat surface 25 formed on its outer periphery in a manner that gives it a straight line in its top-view outer periphery shape. For example, in Figure 19In the rotor core 20M shown, a flat surface 25 is formed on the portion opposite to the first hole 21. According to this structure, even if torque fluctuation increases as a result of reducing leakage flux by using the first permanent magnet 30 and the second permanent magnet 40 and providing a protrusion 22a in the second hole 22, torque fluctuation can be reduced by forming a flat surface 25 on the outer periphery of the rotor core 20M.

[0118] Figure 20 This is an enlarged top view showing a portion of the rotor of modified example 13. For example... Figure 20 As shown in the rotor core 20N of rotor 2N, by forming not only a flat surface 25 but also a bulging surface 26 on the outer periphery, torque ripple can be further reduced. The bulging surface 26 is a curved surface that bulges outwards. Figure 20 It is formed in the part opposite to the second hole 22.

[0119] The stator 3 in the above embodiment is a slotted stator in which an opening is provided between the tops of two adjacent teeth 3a1 of the stator core 3a, but it is not limited to this. Figure 21 This is a partial sectional view of the stator of the electric motor in Variation Example 14. For example, it could also be as follows: Figure 21 As shown in the stator 3O, it is a closed-slot stator formed by connecting the tips of two adjacent teeth 3a1 of the stator core 3a to each other. According to this structure, even if torque fluctuation increases as a result of reducing leakage flux by using the first permanent magnet 30 and the second permanent magnet 40 and providing a protrusion 22a in the second hole 22, torque fluctuation can be reduced by using a closed-slot stator as the stator 3O.

[0120] In the rotor 2 of the above embodiment, the number of magnetic poles is 8, but it is not limited to this. Figure 22 This is a cross-sectional view of the rotor in variant example 15. For example, it could also be as follows: Figure 22 As shown in rotor 2P, the number of magnetic poles is 10. In this case, 10 first permanent magnets 30 and 10 second permanent magnets 40 are arranged circumferentially, with the S and N poles alternating in the circumferential direction as the main magnetic flux. That is, in Figure 22 The rotor 2P shown has a rotor core 20P with 10 first holes 21 and 10 second holes 22 alternately arranged. In addition, the number of magnetic poles of the rotor can be any number other than 8 or 10. As long as the number of magnetic poles of the rotor is 2n (n is a natural number), any number can be used.

[0121] In the above embodiment, all the second holes 22 provided in the rotor core 20 have protrusions 22a, but this is not a limitation. For example, among the plurality of second holes 22, there may also be second holes 22 that do not have protrusions 22a.

[0122] In the above embodiment, the protrusion 22a of the second hole 22 becomes a gap, but it is not limited to this. For example, the second permanent magnet 40 may be embedded entirely in each of the second holes 22, including the protrusion 22a. That is, the top view shape and size of the second permanent magnet 40 may be approximately the same as the top view shape and size of the second hole 22. In this case, the second permanent magnet 40 may also be a sintered magnet, but sintered magnets with shapes other than cuboids are difficult to process, increasing costs. Therefore, when the second permanent magnet 40 is embedded entirely in each of the second holes 22, including the protrusion 22a, the second permanent magnet 40 may be a bonded magnet. In addition, the first permanent magnet 30 is not limited to a sintered magnet and may also be a bonded magnet.

[0123] Furthermore, in the above embodiment, the first permanent magnet 30 is used as the main magnet and the second permanent magnet 40 is used as the auxiliary magnet, but it is not limited to this. For example, the second permanent magnet 40 may be used as the main magnet and the first permanent magnet 30 may be used as the auxiliary magnet.

[0124] Furthermore, the electric motors with rotors described in the above embodiments can be used in a wide variety of electrical devices. For example, they can be used in household electrical devices such as electric vacuum cleaners, air conditioners, and refrigerators, or in industrial electrical devices such as automotive equipment and robots.

[0125] Industrial availability

[0126] The technology disclosed herein can be applied, for example, to rotors such as IPM rotors. The technology disclosed herein can be applied not only to rotors, but also to a wide variety of products such as electric motors with rotors and electrical equipment with electric motors.

[0127] Explanation of reference numerals in the attached figures

[0128] 1. Electric motor; 2. 2A, 2B, 2C, 2D, 2E, 2F, 2H, 2I, 2J, 2K, 2L, 2M, 2N, 2P, Rotor; 3. 3O, Stator; 3a, Stator core; 3a1, Tooth; 3b, Winding coil; 10, Rotating shaft; 20, 20B, 20C, 20D, 20E, 20F, 20H, 20I, 20J, 20K, 20L, 20M, 20N, 20P, Rotor core; 20a, Through hole; 20b, Steel plate; 20br, Bridge section; 21, First hole; 21a, Gap section; 22, Second hole; 22a, Protrusion; 23, Recess; 24, Protrusion; 25, Flat surface; 26, Bulgarian surface; 30, First permanent magnet; 40, Second permanent magnet.

Claims

1. A rotor, wherein, The rotor includes: an iron core having a plurality of first holes and a plurality of second holes; a plurality of first permanent magnets respectively disposed in the plurality of first holes; and a rotating shaft fixed to the iron core. The plurality of first holes and the plurality of second holes are arranged radially about the rotating shaft. The plurality of first holes extend radially along the iron core. The radial length of each of the plurality of second holes in the iron core is smaller than the radial length of each of the plurality of first holes in the iron core. Each of the plurality of second holes has a protrusion located radially inward of the first hole adjacent to the second hole in the circumferential direction of the iron core. Each of the plurality of second holes has a side opposite to the adjacent first hole. The protrusion protrudes from a radially inward portion of the side toward the first hole adjacent to the second hole in the circumferential direction of the iron core.

2. The rotor according to claim 1, wherein, In each of the plurality of second holes, the protrusion is located on the radially inner side of the iron core.

3. The rotor according to claim 1, wherein, In each of the plurality of second holes, the protrusion includes two protrusions located on either side of the second hole, separated by a center line extending radially in the iron core.

4. The rotor according to claim 3, wherein, The two protrusions are arranged symmetrically with respect to the center line.

5. The rotor according to claim 1, wherein, The top view of the protrusion is a shape with a vertex and a width that narrows toward the vertex.

6. The rotor according to claim 1, wherein, The iron core has a bridge portion that serves as the portion between the protrusion and the first hole. The radial length of the iron core in the bridge portion relative to the portion of the protrusion opposite to the adjacent first permanent magnet is defined as l. The width of the bridge portion located at the position furthest radially inward of the portion of the adjacent first permanent magnet opposite to the protrusion is defined as w. The residual magnetic flux density of the first permanent magnet is defined as B. r The saturation magnetization of the iron core is set to J. s When the following relationship is satisfied, [Mathematical Expression 1] 。 7. The rotor according to claim 1, wherein, The protrusion has a corresponding side opposite to one side of the first hole, and the angle between the corresponding side and the first side is greater than -5° and less than 5°.

8. The rotor according to claim 7, wherein, The opposite side is parallel to the first side.

9. The rotor according to any one of claims 1 to 8, wherein, The rotor also includes a plurality of second permanent magnets, which are respectively disposed in the plurality of second holes.

10. The rotor according to claim 9, wherein, The second permanent magnet is not present at the protrusion.

11. The rotor according to claim 9, wherein, At least a portion of the protrusion contains adhesive material for securing the second hole and the second permanent magnet.

12. The rotor according to claim 9, wherein, The second hole is a through hole that passes through the iron core.

13. The rotor according to claim 9, wherein, The iron core is composed of a plurality of steel plates stacked in the axial direction of the rotating shaft. At least two of the plurality of steel plates do not have the second hole, and the steel plate located between the two steel plates that do not have the second hole has the second hole. The second permanent magnet is clamped by the two steel plates that do not have the second hole.

14. The rotor according to claim 9, wherein, The core is composed of a plurality of steel plates stacked in the axial direction of the rotating shaft, at least one of the plurality of steel plates is not provided with the second hole, and two of the second permanent magnets are arranged with the steel plate without the second hole in between.

15. The rotor according to claim 9, wherein, The core is composed of a plurality of steel plates stacked in the axial direction of the rotating shaft, at least one of the plurality of steel plates having a protrusion that extends from a portion of the edge of the second hole toward the inside of the second hole.

16. The rotor according to any one of claims 1 to 8, wherein, None of the multiple second holes contain magnets; the entire structure consists of voids.

17. The rotor according to claim 1, wherein, The core has a bridge portion that serves as the portion between the protrusion and the first hole, and at least a portion of the surface of the bridge portion is recessed in the axial direction of the rotation axis.

18. An electric motor, wherein, The electric motor includes: a rotor according to any one of claims 1 to 17; and a stator disposed opposite to the rotor with an air gap, generating a magnetic force acting on the rotor.

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