Rotor and motor

Abstract

This rotor comprises: a rotary shaft which extends in the axial direction; a rotor core into which the rotary shaft is inserted and which has a plurality of core parts; and a plurality of magnets which are each disposed between two adjacent core parts among the plurality of core parts and which are arranged radially around the rotary shaft. The rotor core has a connection part which connects the plurality of core parts. The connection part connects portions, of the plurality of core parts, excluding outer circumferential edges in the radial direction of the rotor core. Each of the plurality of magnets includes: a first section which forms a magnetic flux directed inward in the radial direction; and a second section which forms a magnetic flux directed outward in the radial direction. The second section has provided thereto a locking part that locks onto the corresponding core part.

Description

Rotor and Motor

[0001] The present disclosure relates to a rotor and a motor including the rotor.

[0002] 2. Description of the Related Art Motors are used in a variety of electrical appliances, such as household appliances and industrial appliances. For example, air conditioners use fan motors in which a rotary fan is attached to the rotating shaft of the motor.

[0003] An interior permanent magnet (IPM) motor is known as a motor having a rotor with a permanent magnet embedded in a rotor core, in which multiple magnets are embedded in the rotor core. A conventional motor of this type is a spoke-type IPM motor having a rotor with multiple magnets arranged in a spoke-like (radial) pattern (see, for example, Patent Documents 1 and 2).

[0004] However, in conventional spoke-type IPM motors, it is difficult to reduce the amount of magnet in the magnet while maintaining the output characteristics.

[0005] Japanese Patent No. 5989878 Japanese Patent No. 5954279

[0006] The present disclosure has been made to solve these problems, and aims to provide a rotor and a motor that can reduce the amount of magnets in the magnet while maintaining the motor's output characteristics.

[0007] In order to achieve the above-mentioned object, one aspect of the rotor according to the present disclosure comprises a rotating shaft extending in an axial direction, a rotor core through which the rotating shaft is inserted and having a plurality of core portions, and a plurality of magnets, each of which is arranged between two adjacent core portions of the plurality of core portions and is arranged radially around the rotating shaft, wherein the rotor core has connecting portions that connect the plurality of core portions, and the connecting portions connect points of each of the plurality of core portions other than the radial outer ends of the rotor core, and each of the plurality of magnets has a first portion that forms a magnetic flux directed radially inward and a second portion that forms a magnetic flux directed radially outward, and the second portion is provided with a locking portion that engages with the core portion.

[0008] Moreover, one aspect of a motor according to the present disclosure includes the rotor described above and a stator that generates a magnetic force acting on the rotor.

[0009] According to the present disclosure, the amount of magnet in the magnet can be reduced while maintaining the output characteristics of the motor.

[0010] FIG. 1 is a cross-sectional view of a motor according to an embodiment, cut along a plane including the axis of the rotating shaft. FIG. 2 is a cross-sectional view of a motor according to an embodiment, cut along a plane perpendicular to the axis of the rotating shaft. FIG. 3 is an enlarged cross-sectional view of a rotor according to an embodiment, cut along a plane perpendicular to the axis of the rotating shaft. FIG. 4 is a diagram showing the configuration of a rotor of a comparative example. FIG. 5 is a diagram showing the relationship between rotation speed and torque in each of the example and the comparative example. FIG. 6 is a diagram showing the relationship between phase current and torque in each of the example and the comparative example. FIG. 7 is a diagram showing the configuration of a rotor of a first modified example. FIG. 8 is a diagram showing the configuration of a rotor of a second modified example.

[0011] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. Each of the embodiments described below represents a specific example of the present disclosure. Therefore, the numerical values, shapes, materials, components, arrangement positions and connection forms of the components, etc. shown in the following embodiments are merely examples and are not intended to limit the present disclosure. Therefore, among the components in the following embodiments, components that are not described in the independent claims that represent the highest concept of the present disclosure will be described as optional components.

[0012] Each figure is a schematic diagram and is not necessarily an exact representation. Therefore, the scales and the like are not necessarily the same in each figure. In all figures, the same reference numerals are used to denote substantially the same components, and redundant explanations will be omitted or simplified.

[0013] In this specification, the terms "up" and "down" do not necessarily refer to the upward direction (vertically upward) and downward direction (vertically downward) in absolute spatial recognition. In this embodiment, for convenience, the direction in which the axis C of the rotating shaft 10 extends is defined as the upward / downward direction. However, this upward / downward direction may differ from the actual upward / downward direction depending on the usage state of the motor 1, etc. In this embodiment, the radial direction of the stator 2 and the rotor 3 (rotor core 20) is defined as the "radial direction," and the rotation direction of the rotor 3 is defined as the "circumferential direction." In other words, the direction perpendicular to the axis C of the rotating shaft 10 of the rotor 3 is defined as the "radial direction," and the direction orbiting the axis C of the rotating shaft 10 is defined as the "circumferential direction." The direction in which the axis C of the rotating shaft 10 extends (the longitudinal direction of the rotating shaft 10) is defined as the "axial direction."

[0014] (Embodiment) First, the overall configuration of a motor 1 according to an embodiment will be described with reference to Figures 1 and 2. Figure 1 is a cross-sectional view of the motor 1 according to the embodiment taken along a plane including the axis C of the rotating shaft 10. Figure 2 is a cross-sectional view of the motor 1 according to the embodiment taken along a plane perpendicular to the axis C of the rotating shaft 10. In Figure 2, the insulator 300 of the stator 2 is omitted.

[0015] 1 , the motor 1 includes a stator 2 and a rotor 3 disposed opposite the stator 2. The motor 1 further includes a first bearing 4, a second bearing 5, a first bracket 6, and a second bracket 7.

[0016] The motor 1 is a molded motor in which the stator 2 is covered with a molding resin 8. The motor 1 is a brushless motor that does not use brushes.

[0017] 1 and 2 , the stator 2 is disposed opposite the rotor 3 with a small air gap between them. The stator 2 is disposed so as to surround the rotor core 20 of the rotor 3. In other words, the motor 1 is an inner rotor type motor in which the rotor 3 is disposed inside the stator 2.

[0018] The stator 2 generates a magnetic force that acts on the rotor 3. Specifically, the stator 2 is configured so that N poles and S poles are generated alternately and repeatedly in the circumferential direction on the air gap surface between the stator 2 and the rotor core 20 of the rotor 3. The stator 2 and the rotor 3 form a magnetic circuit.

[0019] The stator 2 has a stator core 100 (stator iron core) and windings 200. The stator core 100 generates a magnetic force for rotating the rotor 3. As shown in FIG. 2 , the stator core 100 has a plurality of teeth 110 and a yoke 120. The yoke 120 is a back yoke formed on the outside of each tooth 110. The yoke 120 is formed in an annular shape centered on the axis C of the rotating shaft 10.

[0020] The teeth 110 are magnetic pole teeth. The teeth 110 protrude from the yoke 120 toward the rotor 3. Specifically, the teeth 110 extend toward the axis C of the rotating shaft 10. The teeth 110 are arranged at equal intervals in the circumferential direction, with slots formed between two adjacent teeth 110. Therefore, the teeth 110 extend radially in a direction perpendicular to the axis C of the rotating shaft 10 (radial direction). As an example, the stator core 100 is provided with 12 teeth 110.

[0021] Each tooth 110 has an extension 111 that extends from the tip of the inner periphery of the tooth 110 to both sides in the circumferential direction. That is, a pair of extensions 111 is formed at the tip of the inner periphery of the tooth 110 that faces the rotor 3. Each of the pair of extensions 111 is formed to protrude in the circumferential direction from the tip of the inner periphery of the tooth 110. Between two adjacent teeth 110, an opening (slot open) exists between the extension 111 of one tooth 110 and the extension 111 of the other tooth 110.

[0022] Stator core 100 is, for example, a laminated body in which a plurality of steel plates are stacked in the direction in which axis C of rotating shaft 10 extends. Each of the plurality of steel plates is a magnetic material. Each of the plurality of steel plates is, for example, a punched electromagnetic steel plate formed into a predetermined shape. The plurality of steel plates are fixed to each other by caulking, welding, or the like. Stator core 100 is not limited to a laminated body in which a plurality of steel plates are stacked, but may also be a bulk body made of a magnetic material.

[0023] Stator core 100 may be divided into a plurality of sections, each corresponding to one tooth 110. For example, if there are 12 teeth 110, stator core 100 may be made up of 12 core blocks.

[0024] The winding 200 is an armature winding of the stator 2. The winding 200 is a winding coil wound around the stator core 100 as a stator coil. The winding 200 is wound around a plurality of teeth 110 of the stator core 100. Specifically, the winding 200 is wound around each of the plurality of teeth 110 via an insulator 300. In other words, a plurality of windings 200 are wound around the stator 2. In this embodiment, each winding 200 is a concentrated winding coil wound around each tooth 110. Each winding 200 is housed in a slot of the stator core 100.

[0025] When current is applied to the windings 200, magnetic forces are generated from each of the multiple teeth 110 of the stator core 100. For example, the multiple windings 200 are electrically connected as a three-phase winding so that the rotor 3 rotates as a three-phase synchronous motor. In other words, the motor 1 in this embodiment is an interior permanent magnet synchronous motor (IPMSM). In this case, the multiple windings 200 are configured by unit coils for each of the three phases, U-phase, V-phase, and W-phase, which are electrically out of phase with each other by 120 degrees. In other words, the windings 200 attached to each tooth 110 are energized and driven by three-phase alternating current that is applied to each of the U-phase, V-phase, and W-phase units. As a result, a main magnetic flux of the stator 2 is generated in each tooth 110.

[0026] The stator 2 is a molded stator covered with a molded resin 8. For example, the stator 2 can be covered with the molded resin 8 by injection molding. In this embodiment, the molded resin 8 covers the outer portion of the stator 2 over the entire circumferential circumference of the stator 2. Specifically, the molded resin 8 covers the outer portions of the stator core 100 and the windings 200. The molded resin 8 forms a housing that contains the rotor 3. Specifically, the molded resin 8 is formed in a cylindrical shape with a bottom. In this embodiment, the molded resin 8 forms the outer shell of the motor 1.

[0027] The mold resin 8 is made of an insulating resin material with excellent thermal conductivity, such as polyester resin or epoxy resin. The mold resin 8 is also made of a thermosetting resin. In this embodiment, the mold resin 8 is made of a bulk molding compound (BMC) whose main component is unsaturated polyester, which is a thermosetting resin. Specifically, the mold resin 8 is made of a white BMC.

[0028] 1, a circuit board 9 to which windings 200 of the stator 2 are connected is embedded in the mold resin 8. In this case, the ends of the windings 200 of each phase are connected at winding connection portions of the circuit board 9. For example, the circuit board 9 is formed with pattern wiring for electrically connecting the plurality of windings 200 for each of the U-phase, V-phase, and W-phase. The ends of the windings 200 of each phase are electrically connected to the pattern wiring of the circuit board 9 by solder or the like.

[0029] The rotor 3 rotates due to the magnetic force generated in the stator 2. Specifically, the rotor 3 has a rotating shaft 10. The rotor 3 rotates around an axis C of the rotating shaft 10 as the center of rotation.

[0030] The rotor 3 generates a magnetic force that acts on the stator 2. The rotor 3 has a configuration in which N and S poles that form the main magnetic flux are repeated multiple times along the circumferential direction. The direction of the main magnetic flux generated by the rotor 3 is perpendicular to the direction in which the axis C of the rotating shaft 10 extends (radial direction).

[0031] As shown in Figures 1 and 2, the rotor 3 is disposed with an air gap between it and the stator 2. The rotor 3 has a rotating shaft 10, a rotor core 20, and a magnet 30. The rotor 3 is an IPM type rotor in which the magnet 30 is embedded in the rotor core 20. Therefore, the motor 1 in this embodiment is an IPM motor. The detailed structure of the rotor 3 will be described later.

[0032] The rotating shaft 10 of the rotor 3 is supported by a first bearing 4 and a second bearing 5. The first bearing 4 and the second bearing 5 work as a pair of bearings to rotatably support the rotating shaft 10. In this way, the rotating shaft 10 is held in a rotatable state by the first bearing 4 and the second bearing 5. This allows the rotor 3 to rotate relative to the stator 2. As an example, the first bearing 4 and the second bearing 5 are ball bearings. However, this is not limiting. The first bearing 4 and the second bearing 5 may be thrust bearings or the like.

[0033] The first bearing 4 is held by a first bracket 6. The first bracket 6 is fixed to one end of the molded resin 8 in the direction in which the axis C of the rotating shaft 10 extends. The second bearing 5 is held by a second bracket 7. The second bracket 7 is fixed to the other end of the molded resin 8 in the direction in which the axis C of the rotating shaft 10 extends.

[0034] The first bracket 6 and the second bracket 7 are made of a metal material such as iron, for example. For example, the first bracket 6 and the second bracket 7 are made of a metal plate with a uniform thickness.

[0035] In the motor 1 configured as described above, when current is applied to the windings 200 of the stator 2, a field current flows through the windings 200, generating a magnetic field. This generates magnetic flux that flows from the stator 2 toward the rotor 3. Specifically, magnetic flux is generated from each of the multiple teeth 110 of the stator core 100 in the stator 2 toward the rotor core 20 of the rotor 3. Meanwhile, in the rotor 3, magnetic flux that passes through the stator 2 is generated by the magnets 30 embedded in the rotor core 20. A magnetic force generated by the interaction between the magnetic flux generated by the stator 2 and the magnetic flux generated by the magnets 30 of the rotor 3 becomes torque that rotates the rotor 3. This torque causes the rotor 3 to rotate.

[0036] The motor 1 in this embodiment is used in, for example, an air conditioner or other air conditioner. Specifically, the motor 1 is mounted in an outdoor unit of the air conditioner as a fan motor having a rotary fan attached to a rotary shaft 10.

[0037] Next, the detailed structure of the rotor 3 will be described using Fig. 3 while referring to Figs. 1 and 2. Fig. 3 is an enlarged cross-sectional view of the rotor 3 according to the embodiment, taken along a plane perpendicular to the axis of the rotating shaft 10. Fig. 3 illustrates the magnetic field lines generated by the magnet 30. In Fig. 3, hatching of the cross section has been omitted to make the magnetic field lines easier to see.

[0038] As shown in FIGS. 1 to 3, the rotor 3 includes a rotating shaft 10 , a rotor core 20 through which the rotating shaft 10 is inserted, and a plurality of magnets 30 held by the rotor core 20 .

[0039] The rotating shaft 10 has an axis C that is the center when the rotor 3 rotates. The rotating shaft 10 extends in the direction in which the axis C extends. The rotating shaft 10 is a long shaft. The rotating shaft 10 is a metal rod made of a metal material such as SUS (Steel Use Stainless Steel). The rotating shaft 10 is fixed to the rotor core 20. Specifically, the rotating shaft 10 passes through the rotor core 20. The rotating shaft 10 is fixed to the rotor core 20 so as to extend on both sides of the rotor core 20 in the direction in which the axis C extends.

[0040] 1, one end of the rotating shaft 10 protrudes to the outside through the through-hole of the first bracket 6. The portion of the rotating shaft 10 protruding from the first bracket 6 serves as an output shaft. For example, a load such as a rotary fan is attached to one end of the rotating shaft 10.

[0041] The other end of the rotating shaft 10 does not protrude to the outside from the second bracket 7. However, the other end of the rotating shaft 10 may protrude to the outside from the second bracket 7. In other words, both ends of the rotating shaft 10 may protrude from the first bracket 6 and the second bracket 7, respectively.

[0042] As shown in FIG. 1, the rotor core 20 is arranged with an air gap between it and the stator core 100 of the stator 2. As shown in FIG. 2, the rotor core 20 is provided with a plurality of magnet arrangement holes 20a in which magnets 30 are arranged. The magnet arrangement holes 20a are through holes that pass through the rotor core 20 along the direction in which the axis C of the rotating shaft 10 extends. The magnets 30 are inserted into the magnet arrangement holes 20a. In other words, the plurality of magnets 30 are arranged inside the rotor core 20. The magnet arrangement holes 20a are shaped to fit the magnets 30. Specifically, the opening shape of the magnet arrangement holes 20a is the same as the cross-sectional shape of the magnets 30. There may be a slight clearance between the inner surface of the magnet arrangement hole 20a and the outer surface of the magnets 30.

[0043] As shown in Fig. 2, the plurality of magnet arrangement holes 20a and the plurality of magnets 30 are arranged in an annular shape around the rotating shaft 10. The plurality of magnet arrangement holes 20a and the plurality of magnets 30 are provided at equal intervals in the circumferential direction. In this embodiment, ten magnet arrangement holes 20a are provided in the rotor core 20. Therefore, ten magnets 30 are embedded in the rotor core 20 at equal intervals in the circumferential direction around the rotating shaft 10.

[0044] The multiple magnet arrangement holes 20a and the magnets 30 are arranged radially around the rotating shaft 10. Specifically, each of the multiple magnet arrangement holes 20a extends in the radial direction. The multiple elongated magnet arrangement holes 20a are formed in a spoke shape around the rotating shaft 10. Therefore, each of the multiple magnets 30 inserted into the multiple magnet arrangement holes 20a also extends in the radial direction. The multiple magnets 30 are arranged in a spoke shape around the rotating shaft 10. In other words, the rotor 3 is a spoke-type rotor in which the multiple magnets 30 are arranged radially around the rotating shaft 10. Each magnet 30 is arranged so that its longitudinal direction is the radial direction of the rotor core 20 in a plan view. As an example, the plan view shape of each magnet arrangement hole 20a and the plan view shape of each magnet 30 are both rectangular with the radial direction as the longitudinal direction. Each of the multiple magnet arrangement holes 20a has the same shape in a plan view. Similarly, each of the multiple magnets 30 has the same shape in a plan view.

[0045] As shown in Fig. 2, the rotor core 20 has a plurality of core portions 21. Each of the plurality of core portions 21 constitutes a magnetic pole portion of the rotor core 20. The plurality of core portions 21 are arranged in an annular shape around the rotating shaft 10. The magnet arrangement hole 20a is a gap between two adjacent core portions 21 among the plurality of core portions 21. Therefore, each of the plurality of magnets 30 is arranged between two adjacent core portions 21 among the plurality of core portions 21.

[0046] The multiple core portions 21 are not separated but connected to one another. In this embodiment, the rotor core 20 has connecting portions 22. The multiple core portions 21 are connected by the connecting portions 22. The multiple core portions 21 and the connecting portions 22 are configured as a single unit. The connecting portions 22 sequentially connect two circumferentially adjacent core portions 21. In other words, the connecting portions 22 have the function of connecting the multiple core portions 21 to integrate the rotor core 20.

[0047] The connecting portions 22 connect the core portions 21 at locations other than their radially outer peripheral ends. In other words, the rotor core 20 does not have an outer peripheral connecting portion that connects the radially outer peripheral ends of two adjacent core portions 21. In the present embodiment, the connecting portions 22 connect the radially inner peripheral ends of each of the core portions 21. Specifically, as shown in FIG. 3 , the connecting portions 22 have a plurality of inner peripheral connecting portions 22 a and an annular connecting portion 22 b that connects the inner peripheral connecting portions 22 a.

[0048] The multiple inner connecting portions 22a are connected to the inner circumferential ends of the multiple core portions 21, respectively. The inner connecting portions 22a are linear portions extending in the radial direction. One radial end of each inner connecting portion 22a is connected to the core portion 21. The other radial end of each inner connecting portion 22a is connected to the annular connecting portion 22b. In other words, the inner connecting portion 22a is a connecting bridge that connects the core portion 21 and the annular connecting portion 22b. In this embodiment, the ten inner connecting portions 22a connected to the annular connecting portion 22b are arranged radially around the rotating shaft 10.

[0049] The annular connecting portion 22b is provided to surround the rotating shaft 10. In the present embodiment, the annular connecting portion 22b is in contact with the rotating shaft 10. Therefore, the inner surface shape of the annular connecting portion 22b is circular. In the present embodiment, the annular connecting portion 22b has a circular ring shape in plan view. The rotating shaft 10 is fixed to the rotor core 20, for example, by being press-fitted into the annular connecting portion 22b. In this way, the connecting portion 22 not only connects the multiple core portions 21 to integrate the rotor core 20, but also has the function of fixing the rotating shaft 10 to the rotor core 20.

[0050] Because magnetic flux from the magnet 30 passes through the connecting portion 22, providing the connecting portion 22 may result in leakage flux (magnetic flux that does not interlink with the stator windings) that does not contribute to output. Therefore, in this embodiment, to minimize this leakage flux, the connecting portion 22 is flux saturated. Specifically, both the inner circumferential connecting portion 22a and the annular connecting portion 22b are flux saturated. In this case, the connecting portion 22 can be easily flux saturated by making the connecting portion 22 as thin (reduced) as far as possible while still maintaining mechanical strength.

[0051] As shown in FIGS. 1 to 3 , the rotor core 20 is molded with resin 40. As shown in FIG. 3 , the rotor core 20 has a through hole 20b between the annular connecting portion 22b and the magnet 30. The through hole 20b is filled with resin 40. Therefore, the inner peripheral end of the magnet 30 contacts the resin 40. The magnet arrangement hole 20a into which the magnet 30 is inserted is connected to the through hole 20b. The resin 40 filled in the through hole 20b also contacts the pair of inner peripheral connecting portions 22a and the inner peripheral end of the core portion 21. Therefore, the through hole 20b is an area surrounded by the annular connecting portion 22b, the pair of inner peripheral connecting portions 22a, the inner peripheral end of the core portion 21, and the inner peripheral end of the magnet 30. By filling the through hole 20b with resin 40 in this way, the radial inner peripheral end of the magnet 30 can be held by the resin 40.

[0052] The resin 40 is made of an insulating resin material with excellent thermal conductivity, such as polyester resin or epoxy resin. The resin 40 is made of a thermosetting resin. The resin 40 may be made of polybutylene terephthalate (PBT) or the like instead of BMC.

[0053] Rotor core 20 is a laminated body in which a plurality of steel plates, which are magnetic materials, are stacked along the direction in which axial center C of rotating shaft 10 extends. Each of the plurality of steel plates that make up rotor core 20 is, for example, a stamped electromagnetic steel plate formed into a predetermined shape. Each of the plurality of steel plates is fixed to one another by, for example, caulking or welding. In this embodiment, rotor core 20 is made of steel plates of one type of shape. Therefore, the cross-sectional shape of rotor core 20 is all the same in the direction in which axial center C of rotating shaft 10 extends. Rotor core 20 is not limited to a laminated body in which a plurality of steel plates are stacked, but may also be a bulk body made of a magnetic material.

[0054] Each of the multiple magnets 30 embedded in the rotor core 20 is a magnetized permanent magnet. The magnetization direction of each magnet 30 is parallel to the circumferential direction of the rotor 3. The multiple magnets 30 are arranged so that the magnetic pole faces of the same polarity between two adjacent magnets 30 face each other. In other words, between two adjacent magnets 30, the magnetic pole face that becomes the south pole of one magnet 30 faces the magnetic pole face that becomes the south pole of the other magnet 30, or the magnetic pole face that becomes the north pole of one magnet 30 faces the magnetic pole face that becomes the north pole of the other magnet 30.

[0055] As an example, the magnet 30 is a ferrite magnet made of sintered ferrite. The magnet 30 is not limited to a ferrite magnet. For example, the magnet 30 may be a rare earth magnet. In this case, a neodymium rare earth magnet whose main components are neodymium, iron, and boron (Nd—Fe—B) can be used as the magnet 30.

[0056] As shown in FIG. 3 , each of the multiple magnets 30 has a first portion 31 (first region) and a second portion 32 (second region). The second portion 32 is located radially outward of the first portion 31. In other words, the first portion 31 is located radially inward of the second portion 32. The magnet 30 is composed of only the first portion 31 and the second portion 32. The radial length of the first portion 31 is shorter than the radial length of the second portion 32. However, this is not limited to this. Specifically, the radial length of the first portion 31 may be longer than the radial length of the second portion 32.

[0057] The boundary between the first portion 31 and the second portion 32 is near a gap (a location of low magnetic flux density) in the magnetic flux generated in the core portion 21. The first portion 31 is a portion that mainly generates magnetic flux directed radially inward. The second portion 32 is a portion that generates magnetic flux directed radially outward. Specifically, the second portion 32 generates only magnetic flux directed radially outward. In other words, the second portion 32 does not generate magnetic flux directed radially inward. The first portion 31 may generate magnetic flux directed radially outward.

[0058] The width of the first portion 31 (the width in the direction perpendicular to the radial direction) remains constant. The width of the first portion 31 is equal to or greater than the maximum width of the second portion 32. By making the width of the first portion 31 wider in this way, the connecting portion 22 can be easily magnetically saturated. In other words, the first portion 31 plays a role in magnetically saturating the connecting portion 22.

[0059] The second portion 32 has a portion (narrow portion) that is narrower than the first portion 31 in the circumferential direction centered on the rotating shaft 10. This allows a constricted shape to be formed on the outer circumferential surface of the magnet 30. In this embodiment, the second portion 32 has a tapered portion 32a whose width gradually narrows toward the outside in the radial direction, and a straight portion 32b whose width does not change in the circumferential direction centered on the rotating shaft 10. The straight portion 32b is located radially outward of the tapered portion 32a. Both the tapered portion 32a and the straight portion 32b are portions that are narrower than the first portion 31. In this way, by providing the tapered portion 32a in the second portion 32, a constricted portion is formed in which a portion of the outer circumferential surface of the magnet 30 is recessed. The tapered portion 32a forms a convex portion in the core portion 21 that fits into the tapered portion 32a.

[0060] In the present embodiment, the width of the straight portion 32b is equal to or less than half the width of the first portion 31. The maximum radial length of the tapered portion 32a may be equal to or greater than the radial length of the straight portion 32b, or may be less than the radial length of the straight portion 32b.

[0061] Each magnet 30 has a locking portion 33 that locks to the core portion 21. In each magnet 30, the locking portion 33 is provided in the second portion 32. In other words, the locking portion 33 is provided in a position from the boundary between the second portion 32 and the first portion 31 to the tip of the second portion 32. The locking portion 33 is not formed in the first portion 31.

[0062] The locking portion 33 functions as a stopper that prevents the magnet 30 from jumping out of the magnet arrangement hole 20a. In this embodiment, the locking portion 33 is a tapered portion 32a. In this case, the inclined portion of the tapered portion 32a, which is the locking portion 33, locks into the inner surface of the core portion 21, thereby restricting the magnet 30 inserted into the magnet arrangement hole 20a from moving radially outward. In other words, even if the magnet 30 tries to move radially outward, the tapered portion 32a (recessed portion), which is the locking portion 33, fits into the protruding portion of the core portion 21, so the magnet 30 cannot move.

[0063] Here, the features of the rotor 3 according to the embodiment will be described in comparison with a rotor 3X of a comparative example, including the background to the development of the technology of the present disclosure. Fig. 4 is a diagram showing the configuration of the rotor 3X of the comparative example.

[0064] 4, in the rotor 3X of the comparative example, two adjacent core portions 21 in the rotor core 20X are connected not only by an inner peripheral connecting portion 22 but also by an outer peripheral connecting portion 23X. The outer peripheral connecting portion 23X is a bridge that connects the radially outer ends of the two adjacent core portions 21. By providing the outer peripheral connecting portion 23X in this manner, even if the magnet 30X inserted in the magnet arrangement hole 20a between the two adjacent core portions 21 has a rectangular shape, the magnet 30X can be prevented from jumping out of the magnet arrangement hole 20a.

[0065] However, if connecting portion 23X is provided on the outer periphery, magnetic flux from magnet 30X passes through connecting portion 23X and circulates inside rotor core 20X, resulting in leakage magnetic flux (magnetic flux that does not interlink with the stator windings) that does not contribute to the output of the motor.

[0066] Therefore, it is conceivable to eliminate the outer circumferential connecting portion 23X in order to improve the motor output. However, in the structure of the rotor 3X of the comparative example, simply eliminating the connecting portion 23X would eliminate the stopper function of the magnet 30X, which would cause the magnet 30X to jump out of the magnet arrangement hole 20a.

[0067] As a result of thorough research into these issues, the inventors of the present application discovered that by devising the shape of the magnet 30X, it is possible to prevent the magnet 30X from jumping out of the magnet placement hole 20a even if the connecting portion 23X on the outer periphery is eliminated.

[0068] Specifically, as shown in Figure 3, the magnet 30 is divided into a first portion 31 that generates magnetic flux mainly directed radially inward, and a second portion 32 that generates magnetic flux mainly directed radially outward, and the second portion 32 is provided with a locking portion 33 that locks onto the core portion 21.

[0069] With this configuration, even if the outer peripheral connecting portion 23X provided in the rotor 3X of the comparative example is eliminated, the magnet 30 can be locked and held in the core portion 21 by the locking portion 33. Therefore, it is possible to prevent the magnet 30 from jumping out of the magnet arrangement hole 20a. This makes it possible to eliminate the outer peripheral connecting portion 23X. Therefore, leakage magnetic flux due to the connecting portion 23X is eliminated. As a result, it is possible to improve the output of the motor.

[0070] However, providing the magnet 30 with the locking portion 33, which serves as a constricted portion, reduces the amount of magnet used in the magnet 30. This reduces the magnetic force of the second portion 32, which may result in a reduction in motor output. However, in the rotor 3 of this embodiment, the outer peripheral connecting portion 23X is eliminated, thereby eliminating leakage magnetic flux due to the connecting portion 23X. This allows for improved motor output. In other words, the reduction in motor output due to the reduction in magnet amount can be offset by the improvement in motor output due to the elimination of the connecting portion 23X. In other words, the amount of magnet can be reduced while maintaining the motor output characteristics.

[0071] In this regard, a simulation was conducted to compare a motor using the rotor 3 according to the embodiment shown in Fig. 3 (hereinafter referred to as the "Example") with a motor using the rotor 3X shown in Fig. 4 (hereinafter referred to as the "Comparative Example"). The results of the simulation will be described below.

[0072] FIG. 5 is a diagram showing the relationship between rotation speed and torque (NT characteristics) for each of the example and the comparative example. FIG. 6 is a diagram showing the relationship between phase current and torque (IT characteristics) for each of the example and the comparative example. For the NT characteristics shown in FIG. 5, the phase current was fixed at 2.2 Arms, and the rotation speed was varied up to a maximum of 2000 rpm. For the IT characteristics shown in FIG. 6, the phase current was varied up to a maximum of 2.2 Arms, and the average torque was calculated at the current phase angle at which the maximum torque was obtained.

[0073] In the embodiment (FIG. 3), the cross-sectional area of ​​the magnet 30 is 90 mm ２ The cross-sectional area of ​​the magnet 30X in the comparative example (FIG. 4) is 113 mm２ Therefore, the motor of the embodiment can reduce the amount of magnet used as the magnet 30 by approximately 20% compared to the motor of the comparative example.

[0074] Moreover, while the amount of magnet used as magnet 30 was reduced by approximately 20%, it can be seen that the motor of the example and the motor of the comparative example achieved equivalent torque performance, as shown in Figures 5 and 6. The average torque of the motor of the comparative example was 1.14 Nm, and the average torque of the motor of the example was 1.17 Nm. In other words, it was found that the motor of the example can reduce the amount of magnet while maintaining or improving the motor's output characteristics.

[0075] Stress characteristics were measured for the motor of the comparative example and the motor of the example. Specifically, the von Mises stress was measured at a motor rotation speed of 20,000 r / min. As a result, in the structure of the rotor 3X of the comparative example, the maximum stress was at the outer circumferential connecting portion 23X, with a value of 199 MPa. On the other hand, in the structure of the rotor 3 of the example, the maximum stress was at the inner circumferential connecting portion 22, with a value of 98 MPa. Thus, it was found that the rotor 3 of the example can significantly reduce stress compared to the rotor 3X of the comparative example. Moreover, in the motor of the example, the maximum stress was at the inner circumferential connecting portion 22. This further prevents the magnet 30 from jumping out of the magnet placement hole 20a. Therefore, a motor capable of operating at a higher rotational speed can be realized.

[0076] In this embodiment, the rotor core 20 is provided with a connecting portion 22 on the inner periphery side. However, the first portion 31 of the magnet 30 has the same shape (same width) as the magnet 30X in the rotor 3X of the comparative example. This makes it easy to saturate the magnetic flux in the connecting portion 22. This makes it possible to suppress the generation of leakage magnetic flux due to the provision of the connecting portion 22. Therefore, by providing the connecting portion 22, it is possible to suppress a decrease in the output characteristics of the motor.

[0077] As described above, the rotor 3 according to this embodiment includes a rotating shaft 10, a rotor core 20 having a plurality of core portions 21, and a plurality of magnets 30, each disposed between two adjacent core portions 21, arranged radially around the rotating shaft 10. The rotor core 20 has connecting portions 22 connecting the core portions 21. The connecting portions 22 connect the core portions 21 at locations other than the radially outer ends of the rotor core 20. Specifically, the connecting portions 22 connect the radially inner ends of adjacent core portions 21. Each of the magnets 30 has a first portion 31 that generates a magnetic flux that is mainly directed radially inward and a second portion 32 that generates a magnetic flux that is mainly directed radially outward. The second portion 32 is provided with a locking portion 33 that locks to the core portion 21.

[0078] With this configuration, as described above, it is possible to reduce the amount of magnet used as the magnet 30 while maintaining the output characteristics of the motor 1.

[0079] Furthermore, in the rotor 3 according to this embodiment, the second portion 32 of the magnet 30 has a portion that is narrower in width than the first portion 31 in the circumferential direction centered on the rotating shaft 10 .

[0080] This configuration allows the second portion 32 to have a constricted portion as the locking portion 33. Therefore, the magnet 30 can be easily locked to the core portion 21.

[0081] In the rotor 3 according to this embodiment, the second portion 32 of the magnet 30 has a tapered portion 32a whose width gradually narrows toward the outside in the radial direction. The locking portion 33 is the tapered portion 32a.

[0082] With this configuration, the magnet 30 can be reliably locked to the core portion 21 by the tapered portion 32a.

[0083] Furthermore, in the rotor 3 according to this embodiment, the second portion 32 of the magnet 30 has a straight portion 32b whose width does not change in the circumferential direction around the rotating shaft 10. The straight portion 32b is located radially outward of the tapered portion 32a.

[0084] This configuration allows the step of the tapered portion 32a located between the first portion 31 and the straight portion 32b to be increased, thereby enabling the magnet 30 to be more securely locked to the core portion 21 by the tapered portion 32a.

[0085] (Modification) The rotor 3 and the motor 1 according to the present disclosure have been described above based on the embodiment, but the present disclosure is not limited to the above embodiment.

[0086] For example, in the above embodiment, the width of the straight portion 32b of the second portion 32 of the magnet 30 is less than half the width of the first portion 31. However, this is not limited to this. FIG. 7 is a diagram showing the configuration of a rotor 3A according to a first modification. Specifically, as in the rotor 3A shown in FIG. 7, the width of the straight portion 32b of the second portion 32A of the magnet 30A may be greater than half the width of the first portion 31. This allows for a larger amount of magnet to be used as the magnet 30A, thereby improving the motor's output characteristics. In this case, as shown in FIG. 7, the tapered portion 32a may have a smaller inclination angle (a steeper inclination) to facilitate engagement of the magnet 30A with the core portion 21 by the tapered portion 32a. Therefore, the maximum radial length of the tapered portion 32a may be shorter than the radial length of the straight portion 32b. In FIG. 7, the cross-sectional area of ​​the magnet 30A is 113 mm. ２ The average torque of the rotor using rotor 3A in FIG. 7 is 1.32 Nm.

[0087] In the above embodiment, the second portion 32 of the magnet 30B is composed of a tapered portion 32a and a straight portion 32b. However, this is not limited to this. FIG. 8 is a diagram showing the configuration of a rotor 3B according to a second modification. Specifically, as in the rotor 3B shown in FIG. 8, the second portion 32B of the magnet 30B may be composed of a tapered portion 32a (first tapered portion) and a reverse tapered portion 32c (second tapered portion). The reverse tapered portion 32c has a width that gradually increases radially outward. By configuring the second portion 32B with the tapered portion 32a and the reverse tapered portion 32c, the recess of the constricted portion in the second portion 32B can be deepened. This allows the magnet 30B to be reliably locked to the core portion 21 by the locking portion 33. In FIG. 8, the cross-sectional area of ​​the magnet 30B is 108 mm ２ The average torque of the rotor using rotor 3B in FIG. 8 is 1.31 Nm.

[0088] Furthermore, in the above embodiment, the second portion 32 of the magnet 30 has a tapered portion 32a. However, this is not limited to this. Specifically, the second portion 32 of the magnet 30 may be composed of only a straight portion 32b. In this case, the magnet 30 is composed of the first portion 31 and the second portion 32, which is composed of only a straight portion 32b that is narrower than the first portion 31. Therefore, a right-angle step is formed as the locking portion 33 at the boundary between the first portion 31 and the second portion 32 (straight portion 32b).

[0089] In the above embodiment, the plurality of magnets 30 arranged radially around the rotation axis 10 do not necessarily have to be arranged parallel to the radial direction.

[0090] In the above embodiment, the winding 200 of the stator 2 is wound around the stator core 100 in a concentrated winding manner. However, this is not limiting. For example, the winding 200 of the stator 2 may be wound around the stator core 100 in a distributed winding manner.

[0091] In the above embodiment, the motor 1 is a molded motor. However, this is not limiting. The technology of the present disclosure can be applied to motors other than molded motors. In other words, the technology of the present disclosure can be applied to motors in which the stator 2 is not covered with mold resin 8.

[0092] In the above embodiment, the motor 1 has been described as being applied to a fan motor in an air conditioner. However, the present invention is not limited to this. For example, the motor 1 in the above embodiment can be used in a variety of electrical appliances, including household appliances such as vacuum cleaners and refrigerators, and industrial appliances such as automotive appliances and robots.

[0093] In addition, the present disclosure also includes forms obtained by applying various modifications to the above-described embodiments that would occur to those skilled in the art, or forms realized by arbitrarily combining the components and functions of the embodiments within the scope of the present disclosure. The present disclosure also includes any combination of two or more claims from the multiple claims set forth in the claims at the time of filing, provided that there is no technical contradiction. For example, when a dependent claim set forth in the claims at the time of filing is made into a multiple claim or multiple multiple claims that cite all of the superordinate claims within the scope of the technical contradiction, the present disclosure also includes any combination of all claims included in that multiple claim or multiple multiple claims.

[0094] The electric motor according to the present disclosure can be widely used in devices equipped with an electric motor in various fields, including fan motors used in air conditioners and the like.

[0095] REFERENCE SIGNS LIST 1 motor 2 stator 3, 3A, 3B, 3X rotor 4 first bearing 5 second bearing 6 first bracket 7 second bracket 8 molded resin 9 circuit board 10 rotating shaft 20, 20X rotor core 20a magnet arrangement hole 20b through hole 21 core portion 22, 23X connecting portion 22a inner peripheral side connecting portion 22b annular connecting portion 30, 30A, 30B, 30X magnet 31 first portion 32, 32A, 32B second portion 32a tapered portion 32b straight portion 32c reverse tapered portion 33 locking portion 40 resin 100 stator core 110 teeth 111 extension portion 120 yoke 200 winding 300 insulator

Claims

1. A rotor comprising: a rotating shaft extending in the axial direction; a rotor core through which the rotating shaft is inserted and having a plurality of core portions; and a plurality of magnets, each disposed between two adjacent core portions of the plurality of core portions and radially arranged around the rotating shaft, wherein the rotor core has connecting portions that connect the plurality of core portions, and the connecting portions connect each of the plurality of core portions at points other than the radial outer ends of the rotor core, and each of the plurality of magnets has a first portion that forms a magnetic flux directed inward in the radial direction and a second portion that forms a magnetic flux directed outward in the radial direction, and the second portion is provided with a locking portion that locks onto the core portion.

2. The rotor according to claim 1, wherein the second portion has a portion that is narrower in width than the first portion in the circumferential direction about the rotation axis.

3. A rotor according to claim 1, wherein the second portion has a tapered portion whose width gradually narrows toward the outside in the radial direction, and the engaging portion is the tapered portion.

4. A rotor as set forth in claim 3, wherein the second portion has a straight portion whose width does not change in the circumferential direction around the rotation axis, and the straight portion is located radially outward of the tapered portion.

5. A rotor according to any one of claims 1 to 4, wherein the connecting portion connects the inner peripheral ends of each of the two adjacent core portions in the radial direction.

6. A rotor according to claim 5, wherein the connecting portion has a plurality of inner connecting portions connected to the inner circumferential ends of the plurality of core portions, respectively, and an annular connecting portion connecting the plurality of inner connecting portions.

7. The rotor according to claim 6, wherein the rotor core is molded with resin, the rotor core has a through hole between the annular connecting portion and the magnet, and the through hole is filled with the resin.

8. A motor comprising: a rotor according to any one of claims 1 to 4; and a stator that generates a magnetic force acting on the rotor.

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