Rotor and motor

Abstract

The rotor includes: a rotation shaft extending in an axial direction; a rotor core through which the rotation shaft penetrates, including a plurality of core blocks; and a plurality of magnets arranged in a ring shape in an inner portion of the rotor core with the rotation shaft as a center, a plurality of holes are respectively provided in a plurality of core blocks of the rotor core between adjacent two magnets of the plurality of magnets, and the plurality of holes are provided at a position of 55% or more and 95% or less in a radial direction intersecting the axial direction, when a position of a straight line connecting end portions of the adjacent two magnets on an inner peripheral side to each other is 0% and a position of a straight line connecting end portions of the adjacent two magnets on an outer peripheral side to each other is 100%.

Description

Technical Field

[0001] This disclosure relates to rotors and motors including rotors. Background Technology

[0002] Motors are used in various electrical devices, such as household appliances and industrial equipment. Among motors, the IPM (Interior Permanent Magnet) motor is known as a type of motor with embedded permanent magnets. An IPM motor includes an IPM-type rotor in which magnets are arranged in multiple magnet mounting holes located in the rotor core. Conventionally, as an IPM-type rotor, a spoke-type rotor in which multiple magnets are arranged radially is known.

[0003] As a rotor of this IPM type, a spoke-type rotor with holes between adjacent magnets of the rotor core is proposed (see Patent Document 1).

[0004] In IPM type rotors, by setting holes or through holes between adjacent magnets in the rotor core, the average torque is reduced due to the magnetic resistance of the holes or through holes, but torque fluctuations can be reduced.

[0005] The inventors of this application have discovered that, depending on the position of the holes or through holes provided between adjacent magnets in the rotor core, torque fluctuations can be reduced while maintaining a predetermined average torque without reducing the average torque.

[0006] Existing technical documents

[0007] Patent documents

[0008] Patent Document 1: Japanese Patent Application Publication No. 2014-230348 Summary of the Invention

[0009] The purpose of this disclosure is to provide rotors and motors that can reduce torque ripple without reducing the average torque.

[0010] To achieve the above objectives, one embodiment of the rotor disclosed herein includes: a rotating shaft extending in an axial direction; a rotor core through which the rotating shaft passes, comprising a plurality of core blocks; and a plurality of magnets arranged in a ring around the rotating shaft within the rotor core. The plurality of core blocks located between adjacent magnets of the plurality of magnets in the rotor core are each provided with a plurality of holes. When the position of the straight line connecting the inner circumferential ends of the two adjacent magnets is 0%, and the position of the straight line connecting the outer circumferential ends of the two adjacent magnets is 100%, the plurality of holes are located at a position of 55% or more and 95% or less in the radial direction intersecting the axial direction.

[0011] Preferably, the plurality of holes are located at a position of more than 55% and less than 90% in the radial direction.

[0012] Alternatively, the plurality of holes may be arranged symmetrically between two adjacent magnets with respect to the center lines of the magnetic poles generated from the two adjacent magnets respectively.

[0013] Alternatively, the plurality of holes may extend through the rotor core along the axial direction.

[0014] Preferably, the plurality of holes are positioned such that the unloaded magnetic flux density between the plurality of holes is less than ±40% of the unloaded magnetic flux density between one of the two adjacent magnets and the hole closest to that magnet.

[0015] Alternatively, a through hole can be provided between two adjacent magnets among the plurality of magnets in the rotor core, extending through in the axial direction. The through hole is located radially inner than the plurality of holes. When the position of the straight line connecting the inner circumferential ends of the two adjacent magnets is 0%, and the position of the straight line connecting the outer circumferential ends of the two adjacent magnets is 100%, the through hole is located at a position of less than 60% in the radial direction.

[0016] Preferably, the through hole is located at a position of less than 50% in the radial direction.

[0017] Alternatively, the rotor core may be molded from resin, with the resin filling the through holes and the resin not filling the plurality of holes.

[0018] Another embodiment of the rotor disclosed herein includes: a rotating shaft extending in the axial direction; a rotor core through which the rotating shaft passes; and a plurality of magnets arranged in a ring around the rotating shaft inside the rotor core, wherein a through hole is provided between two adjacent magnets in the axial direction in the rotor core, and the through hole is located at a position of less than 60% in the radial direction intersecting the axial direction when the position of the straight line connecting the inner peripheral ends of the two adjacent magnets to each other is 0% and the position of the straight line connecting the outer peripheral ends of the two adjacent magnets to each other is 100%.

[0019] Preferably, the through hole is located at a position of less than 50% in the radial direction.

[0020] Alternatively, the rotor core may be molded from resin, with the resin filling the through-hole.

[0021] Alternatively, the rotor core may have a plurality of core blocks circumferentially divided along the direction surrounding the axis, wherein the area between two adjacent core blocks is a magnet mounting hole for the magnet to be mounted.

[0022] In addition, one embodiment of the motor disclosed herein includes: the rotor described above; and a stator that generates a magnetic force acting on the rotor.

[0023] Preferably, the stator includes a stator core having a plurality of teeth extending toward the rotating shaft. Each of the plurality of teeth has an extension extending from a top portion on the inner circumferential side toward both sides of the circumferential direction. When the center between the respective extensions of two adjacent teeth in the plurality of teeth coincides with the magnetic pole center line between two adjacent magnets of the rotor core, the top end of the extension is located between two tangent lines drawn from the axis of the rotating shaft to one of the plurality of holes.

[0024] According to this disclosure, torque ripple can be reduced without reducing the average torque. Attached Figure Description

[0025] Figure 1 This is a cross-sectional view of the motor in the embodiment.

[0026] Figure 2 This is a perspective view of the rotor core block for the rotor core in the embodiment of the invention.

[0027] Figure 3 This is a diagram schematically illustrating the magnetic flux distribution of the motor in an embodiment.

[0028] Figure 4 It is a graph showing the relationship between the position of the hole in the rotor core and the average torque and torque fluctuation in the rotor of the embodiment.

[0029] Figure 5 It is a graph showing the relationship between the position of the through hole in the rotor core of the rotor in the embodiment and the average torque and torque fluctuation.

[0030] Figure 6 It is a diagram used to illustrate the positional relationship between the holes in the rotor core, the extensions of the stator teeth, and the top ends in the rotor of the embodiment.

[0031] Figure 7 This is a graph showing the relationship between the width of the stator tooth opening and the average torque and torque fluctuation in the rotor of the embodiment. Detailed Implementation

[0032] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. The embodiments described below represent specific examples of the present disclosure. Therefore, the numerical values, shapes, materials, constituent elements, arrangement positions of constituent elements, and connection methods shown in the following embodiments are examples and are not intended to limit the present disclosure. Consequently, any constituent elements in the following embodiments that are not described in the independent claims representing the highest-level concept of the present disclosure will be described as arbitrary constituent elements.

[0033] Each figure is a schematic diagram and may not be a strict representation. Therefore, the scale and other parameters may not be consistent across different figures. In each figure, substantially identical structures are labeled with the same reference numerals, and repetitive descriptions are omitted or simplified.

[0034] In this specification, the terms "up" and "down" do not necessarily refer to the absolute spatial orientation of upward (vertically above) and downward (vertically below). In this embodiment, for ease of explanation, the direction in which the axis C of the rotating shaft 10 extends is defined as the vertical direction. However, this vertical direction may differ from the actual vertical direction due to factors such as the operating state of the motor 1. In this embodiment, the radial direction of the rotor 2 and stator 3 is defined as "radial," and the rotational direction of the rotor 2 is defined as "circumferential." That is, the direction orthogonal to the axis C of the rotating shaft 10 of the rotor 2 is the "radial," and the direction surrounding the axis C of the rotating shaft 10 is the "circumferential." The direction in which the axis C of the rotating shaft 10 extends (the length direction of the rotating shaft 10) is the "axial direction."

[0035] (Implementation Method)

[0036] First, use Figure 1 and Figure 2 The overall structure of the motor 1 in the embodiment will be described. Figure 1 This is a cross-sectional view of motor 1 according to the embodiment. Figure 2 This is a perspective view of the core block 20a for the rotor core 20 of the rotor 2 in the embodiment.

[0037] like Figure 1 As shown, motor 1 includes a rotor 2 and a stator 3. 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. Motor 1 is a brushless motor that does not use brushes.

[0038] The rotor 2 rotates by the magnetic force generated by the stator 3. Specifically, the rotor 2 has a rotation shaft 10. The rotor 2 rotates about the axis C of the rotation shaft 10 as the center of rotation.

[0039] Rotor 2 generates a magnetic force acting on stator 3. Rotor 2 has the following structure: multiple N poles and S poles that 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 (radial) to the direction extending from the axis C of the rotating shaft 10.

[0040] The rotor 2 and stator 3 are separated by an air gap. Specifically, there is a tiny air gap between the surface of the rotor 2 and the surface of the stator 3. The rotor 2 has a rotating shaft 10, a rotor core 20, and a magnet 30, as detailed below. The rotor 2 is an IPM-type rotor in which the magnet 30 is embedded inside the rotor core 20. Therefore, the motor 1 is an IPM motor.

[0041] The stator 3 is disposed opposite to the rotor 2, with an air gap between them. The stator 3 is disposed on the outside of the rotor 2. Specifically, the stator 3 is disposed in a manner that surrounds the rotor core 20 of the rotor 2.

[0042] The stator 3 generates a magnetic force acting on the rotor 2. The stator 3 is configured such that N poles and S poles are alternately and repeatedly generated in the circumferential direction on the air gap surface of the rotor core 20 of the rotor 2. The stator 3 and the rotor 2 together form a magnetic circuit.

[0043] Stator 3 has a stator core 100 and a winding coil 200.

[0044] The stator 3 has a stator core 100 that generates magnetic force to rotate the rotor 2. The stator core 100 has multiple teeth 110 and a magnetic yoke 120. The multiple teeth 110 are magnetic pole teeth. The magnetic yoke 120 is a back magnetic yoke formed on the outside of each tooth 110. The magnetic yoke 120 is formed in an annular shape centered on the axis C of the rotation shaft 10.

[0045] Multiple teeth 110 protrude from the yoke 120 toward the rotor 2. Specifically, the multiple teeth 110 extend toward the axis C of the rotating shaft 10. The multiple teeth 110 form slots between adjacent teeth 110 and are equally spaced in the circumferential direction. Thus, the multiple teeth 110 extend radially in a direction orthogonal to the axis C of the rotating shaft 10. As an example, 12 teeth 110 are provided in the stator core 100.

[0046] In this embodiment, the stator core 100 is a segmented core divided into multiple core blocks 100a along the circumferential direction. That is, the stator core 100 is composed of multiple core blocks 100a. The multiple core blocks 100a are arranged in a circular ring. Specifically, 12 core blocks 100a are arranged in a circular ring. Adjacent core blocks 100a are connected to each other.

[0047] The stator core 100 is divided for each tooth 110. Thus, multiple core blocks 100a each have one tooth 110. Each of the multiple core blocks 100a has an arcuate portion that is a part of the yoke 120. In two adjacent core blocks 100a, the ends of the arcuate portions are connected to each other.

[0048] Each tooth 110 has an extension 111 extending circumferentially from the tip of its inner circumferential side to both sides. That is, a pair of extensions 111 are formed at the tip of the inner circumferential side of the tooth 110 opposite to the rotor 2. The pair of extensions 111 are formed in such a way that they protrude circumferentially from the tip of the inner circumferential side of the tooth 110. In two adjacent teeth 110, there is an opening 130 (open slot) between the extension 111 of one tooth 110 and the extension 111 of the other tooth 110.

[0049] The stator core 100 is, for example, a laminated body formed by stacking multiple steel plates in the direction extending from the axis C of the rotation shaft 10. The multiple steel plates are magnetic. For example, the multiple steel plates are stamped electromagnetic steel plates formed into a predetermined shape. The stator core 100 is divided into multiple core blocks 100a. The stator core 100 is constructed by stacking multiple steel plates in multiple core blocks 100a. That is, each core block 100a is a laminated body formed by stacking multiple steel plates in the direction extending from the axis C of the rotation shaft 10. The multiple steel plates are fixed to each other by riveting or welding, etc. The stator core 100 is not limited to a laminated body formed by stacking multiple steel plates; it can also be a block made of magnetic material.

[0050] The winding coil 200 is a stator coil wound around the stator core 100. The winding coil 200 is wound around each of the multiple teeth 110 of the stator core 100. That is, the winding coil 200 is wound around the teeth 110 of each of the multiple core blocks 100a. Specifically, the winding coil 200 is wound around each of the multiple teeth 110 through an insulator (not shown). Each winding coil 200 is a concentrated winding coil wound around the corresponding tooth 110. Each winding coil 200 is housed in a slot of the stator core 100.

[0051] Magnetic force is generated from the multiple teeth 110 of the stator core 100 by energizing the winding coils 200. For example, the multiple winding coils 200 are electrically connected as three-phase windings so that the rotor 2 rotates as a three-phase synchronous motor. That is, the motor 1 is an interior permanent magnet synchronous motor (IPMSM). In this case, the multiple winding coils 200 are composed of three-phase unit coils, namely the U phase, V phase, and W phase, which are 120 degrees out of phase with each other. That is, the winding coils 200 installed on each tooth 110 are driven by three-phase AC energizing each of the U phase, V phase, and W phase units. As a result, the main magnetic flux as the stator 3 is generated in each tooth 110.

[0052] In the motor 1 configured in this way, when energized, the winding coil 200 of the stator 3 is fed, and an excitation current flows through the winding coil 200 to generate a magnetic field. This generates magnetic flux from the stator 3 toward the rotor 2. Specifically, magnetic flux is generated from the multiple teeth 110 of the stator core 100 of the stator 3 toward the rotor core 20 of the rotor 2. Meanwhile, in the rotor 2, magnetic flux passing through the stator 3 is generated by magnets 30 embedded in the rotor core 20. The magnetic force generated by the interaction between the magnetic flux generated in the stator 3 and the magnetic flux generated from the magnets 30 in the rotor 2 becomes the torque that rotates the rotor 2. Thus, the rotor 2 rotates.

[0053] Next, refer to Figure 1 Use Figure 2 The detailed structure of rotor 2 will be described. Figure 2 This is a perspective view of the core block 20a for the rotor core 20 of the rotor 2 in the embodiment.

[0054] like Figure 1 As shown, the rotor 2 includes a rotating shaft 10, a rotor core 20 through which the rotating shaft 10 passes, and a plurality of magnets 30 held in the rotor core 20.

[0055] The rotating shaft 10 has a center C that becomes the center when the rotor 2 rotates. The rotating shaft 10 extends in the direction of the center C. The rotating shaft 10 is a long, strip-shaped shaft. The rotating shaft 10 is a metal rod made of a metal material such as SUS (Steel Use Stainless). The rotating shaft 10 is fixed to the rotor core 20. Although not shown, the rotating shaft 10 is fixed to the rotor core 20, for example, by passing through the center of the rotor core 20 in a manner that protrudes to both sides of the rotor core 20. A first portion of the rotating shaft 10 protruding to one side of the rotor core 20 is supported by a first bearing. A second portion of the rotating shaft 10 protruding to the other side of the rotor core 20 is supported by a second bearing. A load such as a rotating fan driven by the motor 1 is mounted at either the first or second portion of the rotating shaft 10.

[0056] like Figure 1 As shown, the rotor core 20 and the stator core 100 of the stator 3 are separated by an air gap. The rotor core 20 has multiple magnet mounting holes 23 for mounting magnets 30. The magnet mounting holes 23 are through holes extending along the axis C of the rotation shaft 10 through the rotor core 20. Magnets 30 are inserted into the magnet mounting holes 23. That is, multiple magnets 30 are mounted inside the rotor core 20.

[0057] Multiple magnet mounting holes 23 and multiple magnets 30 are arranged in a ring around the rotation axis 10. The multiple magnet mounting holes 23 and multiple magnets 30 are equally spaced along the circumferential direction. Ten magnet mounting holes 23 are provided in the rotor core 20. Therefore, ten magnets 30 are embedded in the rotor core 20 at equal intervals along the circumferential direction around the rotation axis 10.

[0058] Multiple magnet mounting holes 23 and magnets 30 are arranged radially around the rotation axis 10. Specifically, the multiple magnet mounting holes 23 extend radially. The elongated multiple magnet mounting holes 23 are formed in a spoke shape around the rotation axis 10. Therefore, the multiple magnets 30 inserted into the multiple magnet mounting holes 23 also extend radially. The multiple magnets 30 are arranged in a spoke shape around the rotation axis 10. That is to say, the rotor 2 is a spoke-type rotor with multiple magnets 30 arranged radially. Each magnet 30 is arranged radially to the rotor core 20 in a top view. As an example, the planar shape of each magnet mounting hole 23 and the planar shape of each magnet 30 are both rectangles with the radial direction as the length direction. The planar shapes of the multiple magnet mounting holes 23 are the same. The planar shapes of the multiple magnets 30 are the same.

[0059] The rotor core 20 consists of two cores: an outer core 21 and an inner core 22. The outer core 21 is the first core located radially outward from the inner core 22. The inner core 22 is the second core located radially inward from the outer core 21. The outer core 21 surrounds the inner core 22.

[0060] The outer core 21 is the core that forms the main part of the rotor core 20. The outer core 21 holds a plurality of magnets 30. That is, a plurality of magnet mounting holes 23 are provided in the outer core 21.

[0061] The inner core 22 holds the rotating shaft 10. The rotating shaft 10 passes through the inner core 22. The rotating shaft 10 is fixed to the inner core 22. Specifically, the inner core 22 is provided with an insertion hole 22a. The rotating shaft 10 is fixed to the inner core 22 by pressing or heat fitting into the insertion hole 22a. The inner core 22 is an integral cylindrical component.

[0062] The rotor core 20 has multiple core blocks 20a divided circumferentially. The outer core 21 of the rotor core 20 is also divided circumferentially. The outer core 21 is composed of multiple core blocks 20a. The outer core 21 is divided in the same number as the number of magnets 30. The rotor core 20 holds 10 magnets 30. Therefore, the outer core 21 is composed of 10 core blocks 20a. The multiple core blocks 20a are arranged in a circular ring. Specifically, the 10 core blocks 20a are arranged in a circular ring.

[0063] Multiple core blocks 20a are arranged in such a way that adjacent core blocks 20a do not contact each other. The area between two adjacent core blocks 20a becomes a magnet mounting hole 23 for mounting magnets 30. That is, each magnet 30 is sandwiched between two adjacent core blocks 20a.

[0064] The rotor core 20 is, for example, a laminated body formed by stacking multiple steel plates in the direction extending from the axis C of the rotating shaft 10. The multiple steel plates are magnetic materials. For example, the multiple steel plates are stamped electromagnetic steel plates formed into a predetermined shape. In this embodiment, the outer core 21 and the inner core 22 are each constructed by stacking multiple steel plates. Specifically, each core block 20a of the outer core 21 is constructed by stacking multiple steel plates. That is, each core block 20a is a laminated body formed by stacking multiple steel plates in the direction extending from the axis C of the rotating shaft 10. The multiple steel plates are fixed to each other by riveting or welding, etc. The rotor core 20 is not limited to a laminated body formed by stacking multiple steel plates. The rotor core 20 can also be a block made of magnetic material. That is, each core block 20a and the inner core 22 can also be a block.

[0065] The multiple core blocks 20a constituting the outer core 21 are fixed together by resin 40. Specifically, the multiple core blocks 20a are injection molded, thereby molding the multiple core blocks 20a using resin 40. In this embodiment, both the outer core 21 and the inner core 22 are fixed by resin 40. That is, the multiple core blocks 20a (outer core 21) and the inner core 22 are integrally formed by resin 40. Resin 40 exists between the outer core 21 and the inner core 22. In this way, the rotor core 20 is molded using resin 40. The resin 40 may also cover the radially outer portions of the outer core 21 (core blocks 20a) and the magnet 30, respectively.

[0066] Resin 40 is made of insulating resin materials with excellent thermal conductivity, such as polyester resin or epoxy resin. Alternatively, resin 40 may be made of thermosetting resin. For example, resin 40 may be made of BMC (Bulk Molding Compound), but it may also be made of polybutylene terephthalate (PBT) or the like.

[0067] like Figure 1As shown, multiple holes 24 are provided between two adjacent magnets 30 in the rotor core 20. The multiple holes 24 are located in the outer core 21. Specifically, as... Figure 1 and Figure 2 As shown, multiple holes 24 are provided in each of the multiple core blocks 20a. That is, multiple holes 24 are provided in each of the multiple core blocks 20a located between two adjacent magnets 30.

[0068] Multiple holes 24 are through holes extending along the axis C of the rotating shaft 10 through the rotor core 20. Specifically, multiple holes 24 penetrate the core block 20a. Each of the multiple holes 24 has a circular planar shape. The multiple holes 24 are the same size as each other.

[0069] like Figure 1 As shown, in each of the plurality of core blocks 20a, a plurality of holes 24 are symmetrically arranged with respect to the magnetic pole center line L1 between two adjacent magnets 30. The magnetic pole center line L1 is a line passing through the axis C of the rotation shaft 10 and the midpoint between the two adjacent magnets 30. The magnetic pole center line L1 is generated from each of the two adjacent magnets 30. In this embodiment, two holes 24 are provided for each core block 20a. In each core block 20a, the two holes 24 are symmetrically arranged with respect to the magnetic pole center line L1 between two adjacent magnets 30.

[0070] The plurality of holes 24 are holes used for positioning relative to the mold used when molding the rotor core 20 with resin 40 (mold positioning holes). In other words, the plurality of holes 24 are holes used to determine the position of the plurality of core blocks 20a in relation to the mold used when integrally molding the plurality of core blocks 20a (outer core 21) and inner core 22 with resin 40. Specifically, a mold pin is inserted into the plurality of holes 24. Therefore, in this embodiment, the plurality of holes 24 are through holes that penetrate the core blocks 20a, but the plurality of holes 24 may not penetrate the core blocks 20a as long as a mold pin can be inserted into the plurality of holes 24. In other words, the plurality of holes 24 may also be recesses formed in the core blocks 20a.

[0071] When molding the rotor core 20 using resin 40, pins are inserted into the mold through multiple holes 24, thus... Figure 1 As shown, in the finished rotor 2, the multiple holes 24 are not filled with resin 40. Alternatively, resin 40 may be present locally inside the holes 24.

[0072] A through hole 25 is provided between two adjacent magnets 30 among the plurality of magnets 30 in the rotor core 20. The through hole 25 extends in the direction of the axis C of the rotating shaft 10. The through hole 25 is provided in the outer core 21. Specifically, as Figure 1 and Figure 2As shown, through holes 25 are provided in each of the plurality of core blocks 20a. The through holes 25 penetrate through each core block 20a. Each core block 20a has one through hole 25. In each core block 20a, the through hole 25 is located radially inward compared to the plurality of holes 24. The planar shape of the through hole 25 is such that it tapers radially inward at a constant distance from each of the two adjacent magnets 30.

[0073] The through hole 25 is a hole (resin through hole) provided in a manner that allows the resin 40 to easily wind into it during the molding of the rotor core 20 using resin 40. Therefore, as... Figure 1 As shown, in the finished rotor 2, resin 40 is filled into the through hole 25.

[0074] When the rotor core 20 is molded using resin 40, the magnet 30 is fixed to the rotor core 20 using resin 40. That is, the magnet 30, together with the multiple core blocks 20a (outer core 21) and inner core 22, is integrally formed by resin 40. Alternatively, instead of fixing the magnet 30 to the rotor core 20 using resin 40, adhesive can be separately filled into the magnet mounting holes 23 of the molded article formed by the multiple core blocks 20a (outer core 21) and inner core 22 using resin 40, and the magnet 30 can be inserted into the magnet mounting holes 23 to fix the magnet 30 to the rotor core 20.

[0075] The plurality of magnets 30 embedded in the rotor core 20 are magnetized permanent magnets. The magnetization direction of each magnet 30 is parallel to the circumferential direction of the rotor 2. The plurality of magnets 30 are arranged such that the magnetic pole faces of the same pole of two adjacent magnets 30 face each other. That is, in two adjacent magnets 30, the magnetic pole face of one magnet 30 that is the S pole faces the magnetic pole face of the other magnet 30, or the magnetic pole face of one magnet 30 that is the N pole faces the magnetic pole face of the other magnet 30.

[0076] Magnet 30 is a ferrite magnet composed of sintered ferrite magnets. However, magnet 30 is not limited to ferrite magnets. For example, magnet 30 can also be a rare-earth magnet. In this case, neodymium rare-earth magnets with neodymium, iron, and boron (Nd-Fe-B) as the main components can be used as magnet 30.

[0077] The magnetic flux distribution of the motor 1 constructed in this way is shown in... Figure 3 . Figure 3 This is a diagram schematically showing the magnetic flux distribution of motor 1 in the embodiment. Figure 3 In the diagram, the areas represented by dotted shades indicate regions with higher magnetic flux density.

[0078] In motor 1, such as Figure 3As shown, the rotor core 20 of the rotor 2 is provided with holes 24 and through holes 25. Specifically, each core block 20a is provided with two holes 24 and one through hole 25. In the rotor core 20, the portion with holes 24 and through holes 25 has a higher magnetic reluctance compared to the portion surrounding the holes 24 and through holes 25. Therefore, the magnetic lines of force extending from the magnet 30 toward the teeth 110 of the stator core 100 extend in a manner that avoids the holes 24 and through holes 25, which have higher magnetic reluctance. Thus, as Figure 3 As shown by the dotted shadows, in the region between two adjacent magnets 30 of the rotor core 20 (i.e., core block 20a), the magnetic flux density increases in the portion between the through hole 25 and the magnet 30, the portion between the magnet 30 and the hole 24, and the portion between the two holes 24.

[0079] In this way, by providing holes 24 and through holes 25 between the two magnets 30 of the rotor core 20, multiple magnetic flux channels can be ensured between two adjacent magnets 30. This reduces torque ripple. In particular, the holes 24, located on the outer periphery of the rotor core 20, have a greater impact on the main magnetic flux generated by the rotor core 20; therefore, multiple holes 24 are provided, effectively reducing torque ripple. In this case, in each core block 20a, by reducing the difference in magnetic flux density between one of the two holes 24 and one of the two magnets 30, between the two holes 24, and between the other of the two holes 24 and the other of the two magnets 30, torque ripple can be reduced even more effectively.

[0080] Multiple holes 24 are symmetrically arranged with respect to the magnetic pole center line L1 between two adjacent magnets 30. This ensures that the magnetic flux path at each core block 20a is symmetrical with respect to the magnetic pole center line L1. Consequently, torque ripple can be further reduced.

[0081] The plurality of holes 24 are positioned such that the unloaded magnetic flux density between the plurality of holes 24 is less than ±40% of the unloaded magnetic flux density between one of the two adjacent magnets 30 and the hole 24 closest to that magnet 30. This reduces the difference in magnetic flux density at the channels of the plurality of magnetic fluxes, thereby reducing torque ripple. Alternatively, the distance between the two holes 24 can be ±85% of the distance between the magnet 30 and one of the holes 24.

[0082] In this way, by providing holes 24 or through holes 25 between each adjacent magnet 30 of the rotor core 20, torque fluctuations can be reduced.

[0083] In this case, if holes 24 or through holes 25 that serve as magnetic reluctance are provided between each adjacent magnet 30 of the rotor core 20, it is believed that torque fluctuation can be reduced, but the average torque is reduced.

[0084] However, the inventors of this application investigated whether it was possible to reduce torque ripple while suppressing the decrease in average torque. The inventors discovered that, depending on the position of the holes 24 or through holes 25 provided between adjacent magnets 30 in the rotor core 20, it was possible to reduce torque ripple while suppressing the decrease in average torque. The results of this research are explained below.

[0085] First, refer to Figure 3 Use Figure 4 The results of the study on the position of the hole 24 in the rotor core 20 are explained. Figure 4 This is a diagram showing the relationship between the position of the hole 24 in the rotor core 20 of the rotor 2 in the embodiment and the average torque and torque fluctuation.

[0086] exist Figure 4 In the diagram, the horizontal axis represents the position of the holes 24 in the rotor core 20. Specifically, for the positions of multiple holes 24, such as... Figure 3 The diagram shows the radial positions when the position of the straight line L2 connecting the inner peripheral ends of two adjacent magnets 30 is 0%, and the position of the straight line L3 connecting the outer peripheral ends of two adjacent magnets 30 is 100%. Figure 4 In the diagram, the vertical axis represents the average torque and torque ripple. The average torque is expressed as a percentage, with the initial average torque of motor 1 set at 100%. The torque ripple is expressed as a percentage, obtained by dividing the difference between the maximum and minimum torque generated during one revolution of motor 1 by the average torque generated during one revolution.

[0087] It can be, such as Figure 4 As shown, the multiple holes 24 are positioned radially at a point between 55% and 95%. This allows for effective reduction of torque ripple while maintaining the initial average torque of the motor 1 without decreasing the average torque.

[0088] Even better, such as Figure 4 As shown, multiple holes 24 are positioned radially at a point between 55% and 90%. This minimizes torque ripple without reducing the average torque.

[0089] Next, use Figure 5 The results of the study on the position of the through hole 25 in the rotor core 20 are explained. Figure 5 This is a diagram showing the relationship between the position of the through hole 25 of the rotor core 20 in the rotor 2 of the embodiment and the average torque and torque fluctuation.

[0090] exist Figure 5 In the diagram, the horizontal axis represents the position of the through hole 25 in the rotor core 20. Specifically, regarding the position of the through hole 25, as shown... Figure 3The diagram shows the radial position of the through-hole 25 on its outermost periphery when the position of the straight line L2 connecting the inner periphery ends of two adjacent magnets 30 is 0% and the position of the straight line L3 connecting the outer periphery ends of two adjacent magnets 30 is 100%. The portion of the through-hole 25 located on its innermost periphery (in...) Figure 3 The vertex of an acute angle (the middle point) remains fixed and does not change. Figure 5 In the diagram, the vertical axis represents the average torque and torque ripple. This average torque and torque ripple are compared with... Figure 4 Similarly defined, it is expressed as a percentage.

[0091] It can be, such as Figure 5 As shown, the through hole 25 is positioned at less than 60% of its radial direction. This allows for effective reduction of torque ripple while maintaining the desired average torque of the motor 1 without decreasing the average torque.

[0092] Even better, such as Figure 5 As shown, the through hole 25 is positioned at less than 50% of its radial direction. This allows for the minimization of torque ripple without reducing the average torque.

[0093] According to the inventors' research, the average torque and torque fluctuation are also affected by the relationship between the position of the hole 24 in the rotor core 20 and the width of the opening 130 (open slot) of the tooth 110 in the stator 3. Figure 6 and Figure 7 The results of their research will be explained.

[0094] Figure 6 This is a diagram illustrating the positional relationship between the hole 24 of the rotor core 20 and the top end of the extension 111 of the tooth 110 of the stator 3 in the rotor 2 of the embodiment. Figure 7 This is a diagram showing the relationship between the width of the opening 130 (open slot) of the stator 3 tooth 110 in the rotor 2 of the embodiment and the average torque and torque fluctuation.

[0095] exist Figure 7 In the diagram, the horizontal axis represents the width of the opening 130 (open slot), which is the distance between the extensions 111 of two adjacent teeth 110 of the stator core 100. Specifically, the width of the opening 130 is shown with the following values: 0% for the case where the distance between the extensions 111 of two adjacent teeth 110 is zero (the tips of the extensions 111 are in contact with each other), and 100% for the case where there are no extensions 111 in two adjacent teeth 110. Figure 7 In the diagram, the vertical axis represents the average torque and torque ripple. This average torque and torque ripple are compared with... Figure 4 Similarly defined, it is expressed as a percentage.

[0096] like Figure 6 As shown, when the center between the extensions 111 of two adjacent teeth 110 in the stator core 100 coincides with the magnetic pole center line L1 between two adjacent magnets 30 in the rotor core 20, two tangents drawn from the axis C of the rotating shaft 10 to one of the multiple circular holes 24 are designated as straight lines L4 and L5. Figure 7 In the diagram, line L4 corresponds to the case where the width of opening 130 is 32%, and line L5 corresponds to the case where the width of opening 130 is 72%.

[0097] Therefore, by positioning the tip of the extension 111 of the tooth 110 between two straight lines, namely line L4 and line L5, thus achieving... Figure 7 As shown, the width of the opening 130 can be made to be more than 32% and less than 72%. Therefore, as... Figure 7 As shown, it can effectively reduce torque ripple without reducing the average torque.

[0098] (Modified example)

[0099] The rotor 2 and motor 1 of this disclosure have been described above based on the embodiments. However, this disclosure is not limited to the above embodiments.

[0100] For example, in the above embodiment, the outer core 21 of the rotor core 20 of the rotor 2 is divided into multiple core blocks 20a. However, it is not limited to this. That is, the outer core 21 can also be composed of a single core. In this case, the rotor core 20 may not be composed of two cores, the outer core 21 and the inner core 22, but rather the rotor core 20 may be composed of a single core as a whole.

[0101] Furthermore, in the above embodiment, the top view shape of the magnet 30 inserted into the rotor core 20 of the rotor 2 is rectangular. However, it is not limited to this. For example, the top view shape of the magnet 30 may also be trapezoidal or barrel-shaped.

[0102] Furthermore, in the above embodiment, the stator core 100 is divided into multiple core blocks 100a. However, it is not limited to this. Specifically, the stator core 100 may also be composed of a single core.

[0103] Furthermore, in the above embodiment, the winding coil 200 of the stator 3 is wound on the stator core 100 in a concentrated winding manner. However, it is not limited to this. For example, the winding coil 200 of the stator 3 may also be wound on the stator core 100 in a distributed winding manner.

[0104] Furthermore, this disclosure also includes methods derived from various modifications conceived by those skilled in the art to the above embodiments and variations, or methods achieved by arbitrarily combining the constituent elements and functions of the embodiments without departing from the spirit of this disclosure. It also includes methods derived from arbitrarily combining two or more claims from the plurality of claims recited in the claims at the time of filing of this application, to the extent that they are not technically contradictory. For example, when a claim in the form of reference recited in the claims at the time of filing of this application is set as a plurality of dependent claims or a plurality of dependent claims referencing a plurality of dependent claims, the combination of all claims contained in such plurality of dependent claims or a plurality of dependent claims referencing a plurality of dependent claims is also included in this disclosure.

[0105] Industrial availability

[0106] The technology disclosed herein can be widely used in motors of various electrical equipment, such as household appliances or industrial equipment.

[0107] Explanation of reference numerals in the attached figures

[0108] 1. Motor; 2. Rotor; 3. Stator; 10. Rotating shaft; 20. Rotor core; 20a. Core block; 21. Outer core; 22. Inner core; 22a. Insertion hole; 23. Magnet mounting hole; 24. Hole; 25. Through hole; 30. Magnet; 40. Resin; 100. Stator core; 100a. Core block; 110. Tooth; 120. Magnetic yoke; 130. Opening; 111. Extension; 200. Winding coil.

Claims

1. A rotor, wherein, The rotor includes: A rotational axis that extends in the axial direction; A rotor core, through which the rotating shaft passes, comprises multiple core blocks; and Multiple magnets are arranged in a ring around the rotation axis inside the rotor core. Each of the plurality of core blocks located between two adjacent magnets in the rotor core has a plurality of holes. When the position of the straight line connecting the inner peripheral ends of the two adjacent magnets is 0%, and the position of the straight line connecting the outer peripheral ends of the two adjacent magnets is 100%, the plurality of holes are provided at a position of more than 55% and less than 95% in the radial direction intersecting the axial direction.

2. The rotor according to claim 1, wherein, The plurality of holes are located at a position between 55% and 90% in the radial direction.

3. The rotor according to claim 1, wherein, The plurality of holes are arranged symmetrically between two adjacent magnets with respect to the center lines of the magnetic poles generated from the two adjacent magnets respectively.

4. The rotor according to claim 1, wherein, The plurality of holes penetrate the rotor core along the axial direction.

5. The rotor according to claim 1, wherein, The plurality of holes are positioned such that the unloaded magnetic flux density between the plurality of holes is less than ±40% of the unloaded magnetic flux density between one of the two adjacent magnets and the hole closest to that magnet.

6. The rotor according to any one of claims 1 to 5, wherein, A through hole is also provided between two adjacent magnets among the plurality of magnets in the rotor core, extending through the axis. The through hole is located radially inward than the plurality of holes. When the position of the straight line connecting the inner peripheral ends of the two adjacent magnets is 0%, and the position of the straight line connecting the outer peripheral ends of the two adjacent magnets is 100%, the through hole is located at a position of less than 60% in the radial direction.

7. The rotor according to claim 6, wherein, The through hole is located at a position below 50% in the radial direction.

8. The rotor according to claim 6, wherein, The rotor core is molded from resin. The resin is filled into the through hole. The resin was not filled in the plurality of pores.

9. A rotor, wherein, The rotor includes: A rotational axis that extends in the axial direction; Rotor core, through which the rotating shaft passes; and Multiple magnets are arranged in a ring around the rotation axis inside the rotor core. In the rotor core, a through hole is provided between two adjacent magnets among the plurality of magnets, extending in the axial direction. When the position of the straight line connecting the inner peripheral ends of the two adjacent magnets is 0%, and the position of the straight line connecting the outer peripheral ends of the two adjacent magnets is 100%, the through hole is located at a position of less than 60% in the radial direction intersecting the axial direction.

10. The rotor according to claim 9, wherein, The through hole is located at a position below 50% in the radial direction.

11. The rotor according to claim 9, wherein, The rotor core is molded from resin. The resin is filled into the through hole.

12. The rotor according to any one of claims 1 to 5, 9 to 11, wherein, The rotor core has multiple core blocks divided circumferentially along the direction surrounding the axis. The area between two adjacent core blocks in the plurality of core blocks is a magnet mounting hole for the magnet to be mounted.

13. A motor, wherein, The motor includes: The rotor according to any one of claims 1 to 5, 9 to 11; and The stator generates a magnetic force that acts on the rotor.

14. The motor according to claim 13, wherein, The stator includes a stator core having a plurality of teeth extending toward the rotation axis. The plurality of teeth each have an extension portion extending from the top portion on the inner circumferential side to both sides in the circumferential direction. When the center between the respective extensions of two adjacent teeth in the plurality of teeth coincides with the magnetic pole centerline between the two adjacent magnets of the rotor core, the top of the extension is located between two tangents drawn from the axis of the rotating shaft to one of the plurality of holes.

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