Rotor and motor

Abstract

The problem of the present disclosure is to provide a new heat dissipation structure of a rotor. A rotor (2) comprises: a rotor core (3) that rotates about a rotation axis (A1); and a plurality of permanent magnets (41) that are held by the rotor core (3). The rotor core (3) has: a circular outer circumferential surface (S3) when viewed from a direction along the rotation axis (A1); a first surface (S1) provided on one side in a direction along the rotation axis (A1); a second surface (S2) provided on the side opposite the one side in the direction along the rotation axis (A1); a cavity (C1) provided inward from the outer circumferential surface (S3) and opening at least one of the first surface (S1) and the second surface (S2); and at least one fin (33) disposed in the cavity (C1). The at least one fin (33) causes the flow of a refrigerant present in the cavity (C1) during rotation of the rotor core (3).

Description

Rotor and motor

[0001] The present disclosure relates generally to rotors and motors, and more particularly to a rotor including a rotor core and a motor including the rotor.

[0002] The rotor described in Patent Document 1 is composed of a rotor shaft, a yoke integrally attached to the rotor shaft, and a permanent magnet housed in the yoke. The yoke has ventilation holes between the rotor shaft and the permanent magnet to promote heat dissipation from the rotor.

[0003] Japanese Patent Application Laid-Open No. 2005-192365

[0004] An object of the present disclosure is to provide a new heat dissipation structure for a rotor.

[0005] A rotor according to one aspect of the present disclosure includes a rotor core that rotates about a rotation axis and a plurality of permanent magnets held by the rotor core. The rotor core has a circular outer peripheral surface when viewed along the rotation axis, a first surface provided on one side along the rotation axis, a second surface provided on the opposite side along the rotation axis, a cavity provided inside the outer peripheral surface and opening at least one of the first surface and the second surface, and at least one fin disposed in the cavity. The at least one fin generates a flow of refrigerant present in the cavity when the rotor core rotates.

[0006] A motor according to one aspect of the present disclosure includes the rotor and a stator, wherein the rotor rotates relative to the stator.

[0007] FIG. 1 is a perspective view of a rotor core of a motor according to a first embodiment. FIG. 2 is an exploded perspective view of the rotor core. FIG. 3 is a cross-sectional view of the rotor core. FIG. 4 is a plan view of the motor. FIG. 5 is a layout diagram of a plurality of permanent magnets of the motor. FIG. 6 is a cross-sectional view of the motor. FIG. 7 is a cross-sectional view of a motor according to a first modified example. FIG. 8 is a perspective view of a rotor core according to a second embodiment. FIG. 9 is an exploded perspective view of the rotor core. FIG. 10 is a cross-sectional view of the rotor core. FIG. 11 is a perspective view of a rotor core according to a third embodiment. FIG. 12 is an exploded perspective view of the rotor core. FIG. 13 is a cross-sectional view of the rotor core. FIG. 14 is a perspective view of a rotor core according to a fourth embodiment. FIG. 15 is an exploded perspective view of the rotor core. FIG. 16 is a cross-sectional view of the rotor core.

[0008] In the following embodiments, the rotor 2 and motor 1 of the present disclosure will be described using the drawings. However, the following embodiments are merely a portion of various embodiments of the present disclosure. The following embodiments can be modified in various ways depending on the design, etc., as long as the object of the present disclosure can be achieved. Furthermore, the following embodiments, including modified examples, may be realized by combining them as appropriate. Furthermore, the drawings described in the following embodiments are schematic diagrams, and the ratios of the sizes and thicknesses of the components in the drawings do not necessarily reflect the actual dimensional ratios.

[0009] As indicated by the double-headed arrow in each drawing, the direction along the rotation axis A1 (see FIG. 6) of the rotor core 3 is defined as the front-rear direction. However, this definition is not intended to limit the direction in which the rotor 2 and motor 1 are used. Furthermore, the double-headed arrow indicating the front-rear direction in each drawing is merely for the purpose of explanation and does not have any substance.

[0010] (Embodiment 1) (Overview) As shown in Fig. 4, the rotor 2 includes a shaft 21, a rotor core 3, and a magnet section 4. Fig. 5 is an enlarged view of the dashed-dotted line portion in Fig. 4. As shown in Fig. 5, the magnet section 4 has a plurality of permanent magnets 41.

[0011] Fig. 1 is a perspective view of the rotor core 3. Fig. 2 is an exploded perspective view of the rotor core 3. In Fig. 2, two elements (an outer cylinder portion 32 and other elements) constituting the rotor core 3 are shown exploded, but the multiple elements constituting the rotor core 3 may be connected seamlessly. Alternatively, the multiple elements constituting the rotor core 3 may be formed separately and joined later. In the following description, the multiple elements constituting the rotor core 3 will be described as being connected seamlessly.

[0012] 1 to 5 , the rotor 2 includes a rotor core 3 that rotates about a rotation axis A1 and a plurality of permanent magnets 41 held by the rotor core 3. The rotor core 3 has a circular outer peripheral surface S3 when viewed along the rotation axis A1, a first surface S1 provided on one side along the rotation axis A1, a second surface S2 provided on the opposite side along the rotation axis A1, a cavity C1 that is provided inside the outer peripheral surface S3 and has at least one of the first surface S1 and the second surface S2 open, and at least one fin 33 disposed in the cavity C1. The at least one fin 33 generates a flow of refrigerant present in the cavity C1 when the rotor core 3 rotates.

[0013] According to the above configuration, the provision of at least one fin 33 improves the heat dissipation efficiency of the rotor core 3. Furthermore, compared to a case in which the at least one fin 33 is made of a separate member from the rotor core 3, the number of components of the rotor 2 can be reduced, and the number of steps required to assemble the rotor 2 can also be reduced. Furthermore, the provision of the hollow portion C1 allows the weight of the rotor 2 to be reduced.

[0014] (Details) (1) Motor As shown in Fig. 4 and Fig. 6, the motor 1 includes a rotor 2 and a stator 5. The rotor 2 rotates relative to the stator 5. The motor 1 of this embodiment is an inner rotor type motor.

[0015] The motor 1 is, for example, a vernier motor. Vernier motors can generate high torque at low rotation speeds, and are expected to be used in direct drive applications without reduction gears. It is known that in a vernier motor, when the number of pole pairs of the stator winding is p, the number of stator slots is Ns, and the number of pole pairs of the rotor magnet is Nr, the relationship Nr = Ns ± p is satisfied.

[0016] In a vernier motor, the amount of heat generated by the rotor 2 is relatively large during high-speed rotation. Therefore, in the present disclosure, the rotor core 3 is provided with at least one fin 33 (four in the illustrated example), thereby improving the heat dissipation efficiency of the rotor 2.

[0017] As shown in FIG. 6 , the motor 1 further includes a first bearing 11 , a second bearing 12 , and a motor housing 13 .

[0018] The motor housing 13 accommodates the rotor 2, the stator 5, the first bearing 11, and the second bearing 12. The stator 5 is fixed to the motor housing 13. The first bearing 11 and the second bearing 12 are fixed to the motor housing 13 and rotatably hold the shaft 21 of the rotor 2. The rotational torque of the shaft 21 is transmitted to the load. In other words, torque is applied from the motor 1 to the load.

[0019] The motor housing 13 is made of a highly heat-conductive material, such as metal.

[0020] (2) Mounting Target of Motor The motor 1 is mounted to a mounting target member. In this embodiment, the mounting target member is a metal plate 8. The motor housing 13 has a mounting portion 131 that is mounted to the metal plate 8. As an example, the mounting portion 131 is an outer wall portion of the motor housing 13.

[0021] As described above, the direction along the rotation axis A1 of the rotor core 3 is defined as the front-rear direction. The mounting portion 131 is a portion that includes the front surface 1300 of the motor housing 13. The motor housing 13 is mounted to the metal plate 8 at the mounting portion 131 so that the metal plate 8 is located in front of the motor housing 13. As an example, the motor housing 13 is mounted to the metal plate 8 at the mounting portion 131 by screws.

[0022] (3) Drive Unit The motor 1 further includes a drive unit 9. The drive unit 9 includes an inverter circuit 91, a control circuit 92, and an encoder unit E1. The inverter circuit 91 generates power to drive the motor 1. The control circuit 92 controls the inverter circuit 91. For example, the control circuit 92 controls the inverter circuit 91 by driving switching elements included in the inverter circuit 91. In this way, the control circuit 92 controls the rotation of the rotor 2. More specifically, the control circuit 92 controls the inverter circuit 91 by controlling the on / off of switching elements included in the inverter circuit 91 based on the rotation angle of the shaft 21 detected by the encoder unit E1.

[0023] The encoder unit E1 may be, for example, a magnetic encoder that includes a permanent magnet that rotates together with the shaft 21 and a magnetic sensor that is attached to a non-rotating portion and detects changes in the magnetic field. Alternatively, the encoder unit E1 may be, for example, an optical encoder that includes an optical slit that rotates together with the shaft 21, a light-emitting element that is attached to the non-rotating portion and emits light to the optical slit, and a light-receiving element that is attached to the non-rotating portion and receives the light that has passed through the optical slit.

[0024] The drive unit 9 is disposed outside the motor housing 13. A housing 90 of the drive unit 9 is in contact with the motor housing 13. More specifically, the housing 90 of the drive unit 9 is in contact with a rear surface 1301 of the motor housing 13. The drive unit 9 dissipates heat, for example, through the motor housing 13 in addition to dissipating heat from the housing 90 of the drive unit 9 and a heat dissipation mechanism provided in the drive unit 9 itself.

[0025] The portion of the housing 90 of the drive unit 9 that contacts the rear surface 1301 of the motor housing 13 may be shared with the motor housing 13. In other words, the portion of the housing 90 that contacts the rear surface 1301 of the motor housing 13 can be omitted.

[0026] (4) Stator When viewed from the front-rear direction, the stator 5 surrounds the rotor 2 (see FIG. 4). As shown in FIGS. 4 and 6, the stator 5 includes a stator core 6 and a plurality of windings 7. The stator core 6 includes a ring 61 and a plurality of teeth 62.

[0027] The ring 61 has a cylindrical shape. The axial direction of the ring 61 is along the front-rear direction. The teeth 62 protrude from the inner surface of the ring 61 toward the center of the ring 61.

[0028] The plurality of windings 7 correspond one-to-one to the plurality of teeth 62. Each winding 7 is wound around a corresponding tooth 62. As an example, the stator 5 further includes an insulator having electrical insulation properties, and each winding 7 is wound around a corresponding tooth 62 via the insulator.

[0029] Each of the plurality of windings 7 generates a magnetic flux when energized. Electromagnetic interaction between the magnetic flux generated from the plurality of windings 7 and the plurality of permanent magnets 41 of the rotor 2 causes the rotor 2 to rotate relative to the stator 5.

[0030] As an example, the stator core 6 is formed by stacking multiple steel plates in the thickness direction. In other words, the stator core 6 is a so-called laminated core. In this case, the stator core 6 includes multiple steel plates. The multiple steel plates are, for example, bonded together so that adjacent steel plates are bonded together in the thickness direction. The stacking direction of the multiple steel plates is along the front-to-rear direction. More specifically, each steel plate is an electromagnetic steel plate. Each steel plate is made of a magnetic material. Each steel plate is, for example, a silicon steel plate.

[0031] (5) Rotor As shown in Figures 4 and 6, the rotor 2 includes a shaft 21, a rotor core 3, and a magnet section 4. The magnet section 4 has a plurality of permanent magnets 41 (see Figure 5).

[0032] The shape of the outer peripheral surface S3 of the rotor core 3 is the same as the shape of the side surface of a cylinder. The plurality of permanent magnets 41 are arranged on the outer peripheral surface S3 of the rotor core 3. As an example, the plurality of permanent magnets 41 are attached to the outer peripheral surface S3 of the rotor core 3.

[0033] Figure 5 shows the arrangement of the multiple permanent magnets 41 of the magnet unit 4 in the area surrounded by the dashed line in Figure 4. In Figure 5, the arrows superimposed on each permanent magnet 41 indicate the magnetization direction of the permanent magnet 41. The base end of the arrow is the south pole, and the tip end of the arrow is the north pole.

[0034] 5, the multiple permanent magnets 41 are arranged in a Halbach array. In other words, if the multiple permanent magnets 41 arranged in the circumferential direction are referred to in order as the first, second, third, ..., Nth permanent magnets, the k+1th permanent magnet (1≦k≦N−1) has a magnetization direction that differs by 90 degrees in a certain direction (for example, clockwise) from the kth permanent magnet.

[0035] By adopting the Halbach array, the magnetic flux of the magnet portion 4 is concentrated on the stator 5 side.

[0036] Furthermore, when the Halbach array is employed, the structure of the rotor core 3 is less likely to affect the magnetic flux distribution. Therefore, even if the rotor core 3 has the cavity C1 and the fins 33, the possibility of the magnetic flux distribution changing can be reduced compared to when the rotor core 3 does not have the cavity C1 or the fins 33. This reduces the possibility that the characteristics of the motor 1 will change due to the rotor core 3 having the cavity C1 or the fins 33.

[0037] Furthermore, if the rotor 2 has a relatively large number of magnetic poles, the structure of the rotor core 3 is less likely to cause a decrease in the torque of the motor 1. In other words, even if the rotor core 3 has the hollow portion C1 and fins 33 as in this embodiment, if the rotor 2 has a relatively large number of magnetic poles, the torque of the motor 1 is less likely to decrease. For example, if the diameter of the motor 1 is approximately 120 mm, the number of magnetic poles of the rotor 2 is preferably 16 or more. If the diameter of the motor 1 is different, the preferable number of magnetic poles can be set by proportionally converting the above numerical values.

[0038] Furthermore, when the multiple permanent magnets 41 are closely arranged, the structure of the rotor core 3 is less likely to cause a decrease in the torque of the motor 1. In other words, even if the rotor core 3 has a hollow portion C1 and fins 33 as in this embodiment, when the multiple permanent magnets 41 are closely arranged, the torque of the motor 1 is less likely to decrease. For example, when the diameter of the motor 1 is approximately 120 mm, the length of each of the multiple permanent magnets 41 measured along the circumferential direction of the rotor core 3 is preferably 5 mm or less. When the diameter of the motor 1 is different, the preferable magnet length can be set by proportionally converting the above numerical values.

[0039] As shown in FIGS. 1 to 3, the rotor core 3 has an inner cylindrical portion 31, an outer cylindrical portion 32, and a plurality of fins 33 (four in the illustrated example).

[0040] The inner cylinder portion 31 includes a hub 311 and a connecting portion 312. The hub 311 has a cylindrical shape with an axial direction along the front-rear direction. The connecting portion 312 has a cylindrical shape with an axial direction along the front-rear direction. The hub 311 is concentric with the connecting portion 312. The hub 311 protrudes forward from the front end of the connecting portion 312.

[0041] The inner diameter of the hub 311 is equal to the inner diameter of the connecting portion 312. The outer diameter of the hub 311 is smaller than the outer diameter of the connecting portion 312.

[0042] The outer cylinder portion 32 has a cylindrical shape with its axial direction aligned in the front-to-rear direction. The outer cylinder portion 32 is concentric with the inner cylinder portion 31. The inner cylinder portion 31 is disposed inside the outer cylinder portion 32. The outer diameter of a connecting portion 312 of the inner cylinder portion 31 is equal to the inner diameter of the outer cylinder portion 32. The hub 311 of the inner cylinder portion 31 is connected to the outer cylinder portion 32 via the connecting portion 312.

[0043] The outer peripheral surface S3 of the rotor core 3 is the outer peripheral surface of the outer cylindrical portion 32.

[0044] The front surface of the outer cylindrical portion 32 is flush with the front surface of the hub 311. The rear surface of the outer cylindrical portion 32 is flush with the rear surface of the connecting portion 312.

[0045] The first surface S1 of the rotor core 3 includes the front surface of the outer cylindrical portion 32 and the front surface of the hub 311. The second surface S2 of the rotor core 3 includes the rear surface of the outer cylindrical portion 32 and the rear surface of the connecting portion 312.

[0046] The shaft 21 has a cylindrical shape. The shaft 21 is inserted into the inner cylindrical portion 31. As a result, the shaft 21 is held in the inner cylindrical portion 31. The shaft 21 rotates together with the rotor core 3.

[0047] The rotation axis A1 of the rotor core 3 coincides with the central axis of the shaft 21 .

[0048] When viewed from the front-rear direction, the multiple fins 33 extend radially from the hub 311. In other words, the multiple fins 33 are arranged radially around the center of rotation of the rotor core 3.

[0049] Each of the fins 33 has a plate-like shape. More specifically, each of the fins 33 has a rectangular parallelepiped shape. The longitudinal direction of each of the fins 33 is aligned with the front-rear direction but is inclined relative to the front-rear direction toward the rotation direction of the rotor core 3. More specifically, when viewed from the rotation axis A1 of the rotor core 3, each of the fins 33 has a / (slash) shape.

[0050] A gap is provided between each of the plurality of fins 33 and the outer cylindrical portion 32 .

[0051] The rotor core 3 has a cavity C1. The cavity C1 is a gap between the hub 311 and the outer cylinder portion 32. A plurality of fins 33 are arranged in the cavity C1. The cavity C1 opens onto the first surface S1 of the rotor core 3. In other words, the cavity C1 penetrates the first surface S1 (front surface) of the rotor core 3.

[0052] In this way, of the first surface S1 and the second surface S2 of the rotor core 3, the surface (first surface S1) closer to the mounting portion 131 (see Figure 6) that is attached to the metal plate 8 is open to the cavity portion C1.

[0053] Furthermore, the fins 33 are adjacent to the first surface S1 or the second surface S2, whichever is closer to the mounting portion 131 (the first surface S1). The distance between the fins 33 and the first surface S1 is shorter than the distance between the fins 33 and the second surface S2.

[0054] As an example, the rotor core 3 is formed by stacking a plurality of steel plates in the thickness direction. In other words, the rotor core 3 is a so-called laminated core. In this case, the rotor core 3 includes a plurality of steel plates. The plurality of steel plates are, for example, bonded together so that adjacent steel plates are bonded together in the thickness direction. The stacking direction of the plurality of steel plates is along the front-to-rear direction. More specifically, each steel plate is an electromagnetic steel plate. Each steel plate is made of a magnetic material. Each steel plate is, for example, a silicon steel plate.

[0055] As another example, the rotor core 3 may be formed by 3D (three-dimensional) printing.

[0056] (6) Heat Dissipation of Rotor When the rotor core 3 rotates, the fins 33 of the rotor core 3 also rotate. The rotation of the fins 33 causes a flow of the refrigerant present in the cavity C1. The refrigerant is, for example, air. Note that the refrigerant may also be, for example, water or oil.

[0057] For example, the refrigerant flows from the cavity C1 to the front of the rotor core 3, and then flows to the rear of the rotor core 3 through the gaps between the multiple teeth 62 of the stator 5 and the gaps between the stator 5 and the rotor 2.

[0058] (7) Heat Dissipation of the Driving Unit As shown in FIG. 6, the motor 1 includes a driving unit 9 and a motor housing 13 that houses the rotor 2 and the stator 5.

[0059] The drive unit 9 is in contact with the motor housing 13. Therefore, heat generated in the drive unit 9 can be dissipated via the motor housing 13.

[0060] The motor housing 13 is attached to the metal plate 8. The heat received by the motor housing 13 from the drive unit 9 at the rear surface 1301 is transferred to the metal plate 8 via the motor housing 13.

[0061] Furthermore, heat received by the rear surface 1301 of the motor housing 13 from the drive unit 9 is transferred from the front surface 1300 of the motor housing 13 to the metal plate 8 via the coolant (air, etc.) inside the motor housing 13. The flow generated in the coolant by the rotation of the multiple fins 33 improves the efficiency of heat transfer via the coolant.

[0062] (8) Modification 1 A motor 1X according to Modification 1 of the first embodiment will be described below with reference to FIG.

[0063] The motor 1X of the present modified example 1 differs from the above-described embodiment in the arrangement of the drive unit 9.

[0064] A part of the drive unit 9 (a part of the housing 90) is housed in a recess 1302 provided in a rear surface 1301 of the motor housing 13. The entire drive unit 9 may be housed in the recess 1302. In other words, it is sufficient that at least a part of the drive unit 9 is housed in the recess 1302. Furthermore, at least a part of the drive unit 9 may be disposed in the internal space of the motor housing 13.

[0065] At least a portion of the drive unit 9 is disposed in a space SP2 surrounded by the rear ends of the windings 7. The space SP2 is a circular space when viewed from the rear. The space SP2 overlaps with the rotor 2 when viewed from the rear.

[0066] At least a portion of the drive unit 9 may be disposed in a space SP1 surrounded by the front ends of the plurality of windings 7. The space SP1 is a circular space when viewed from the front. The space SP1 overlaps with the rotor 2 when viewed from the front.

[0067] In this modification 1, the space SP1 or the space SP2 can be effectively utilized. Furthermore, since at least a portion of the drive unit 9 is exposed to the refrigerant (air or the like) in the motor housing 13, the heat dissipation efficiency of the drive unit 9 can be improved.

[0068] In the first embodiment, as an example, a case where concentrated winding is used as the winding structure of the multiple windings 7 has been described. However, depending on the number of poles and slots of the motor 1, a winding structure such as distributed winding or fractional slot winding may also be used.

[0069] Distributed winding can produce high torque. When distributed winding is employed, the amount of protrusion of the windings 7 from the stator core 6 in the front-to-rear direction increases. In other words, the front ends of the windings 7 are positioned further forward, and the rear ends of the windings 7 are positioned further rearward. Therefore, the space SP1 enclosed by the respective front ends of the multiple windings 7 and the space SP2 enclosed by the respective rear ends of the multiple windings 7 become larger. By arranging at least a portion of the drive unit 9 in the space SP1 or the space SP2, the space SP1 or the space SP2 can be effectively utilized.

[0070] Second Embodiment A rotor core 3A according to a second embodiment will be described below with reference to Figures 8 to 10. The configuration of the motor 1 other than the rotor core 3A is the same as that of the first embodiment, and therefore description thereof will be omitted.

[0071] 9 shows the three elements (the outer cylinder portion 32, the inner protrusions 34, and other elements) that make up the rotor core 3A in an exploded view, but the multiple elements that make up the rotor core 3A may be connected seamlessly. Alternatively, the multiple elements that make up the rotor core 3A may be formed separately and then joined together later. In the following description, the multiple elements that make up the rotor core 3A will be described as being connected seamlessly.

[0072] The rotor core 3A has an inner cylindrical portion 31A, an outer cylindrical portion 32, a plurality of fins 33 (four in the illustrated example), and inner protrusions 34.

[0073] The inner cylindrical portion 31A has a cylindrical shape with an axial direction along the front-rear direction, and the shaft 21 (see FIG. 6) is inserted into the inner cylindrical portion 31A.

[0074] The outer cylinder 32 has a cylindrical shape with its axial direction aligned in the front-rear direction. The outer cylinder 32 is concentric with the inner cylinder 31A. The inner cylinder 31A is disposed inside the outer cylinder 32.

[0075] The inner protrusion 34 has a cylindrical shape with its axial direction aligned in the front-rear direction. The inner protrusion 34 is concentric with the outer cylindrical portion 32. The inner protrusion 34 protrudes from the inner peripheral surface of the outer cylindrical portion 32 toward the center of the outer cylindrical portion 32.

[0076] The hollow portion C1 is a space surrounded by the inner cylinder portion 31A, the outer cylinder portion 32, and the inner protrusion 34. The hollow portion C1 includes a front side portion C11 between the inner cylinder portion 31A and the outer cylinder portion 32, and a rear side portion C12 between the inner cylinder portion 31A and the inner protrusion 34. A plurality of fins 33 are arranged in the front side portion C11. The rear side portion C12 is a space behind the front side portion C11. The rear side portion C12 is connected to the front side portion C11.

[0077] 10 (a cross section taken along the rotation axis A1), the front portion C11 on which the fins 33 are arranged is longer in a direction perpendicular to the front-to-rear direction than the rear portion C12. In other words, due to the provision of the inner protrusions 34, the rear portion C12 has a smaller radial width than the front portion C11. By providing a difference in width between the rear portion C12 and the front portion C11, the negative pressure in the cavity C1 is adjusted, making it easier for the refrigerant to flow through the cavity C1.

[0078] The outer peripheral surface S3 of the rotor core 3A is the outer peripheral surface of the outer cylindrical portion 32.

[0079] The front surface of the outer cylindrical portion 32 is flush with the front surface of the inner cylindrical portion 31 A. The rear surface of the outer cylindrical portion 32 is flush with the rear surface of the inner cylindrical portion 31 A and the rear surface of the inner protrusion 34.

[0080] The first surface S1 of the rotor core 3A includes the front surface of the outer cylindrical portion 32 and the front surface of the inner cylindrical portion 31A. The second surface S2 of the rotor core 3A includes the rear surface of the outer cylindrical portion 32, the rear surface of the inner cylindrical portion 31A, and the rear surfaces of the inner protrusions 34.

[0081] The cavity C1 is open to both the first surface S1 and the second surface S2 of the rotor core 3A. That is, the front side portion C11 of the cavity C1 penetrates the first surface S1 (front surface) of the rotor core 3A. The rear side portion C12 of the cavity C1 penetrates the second surface S2 (rear surface) of the rotor core 3A. The cavity C1 penetrates between the first surface S1 and the second surface S2 of the rotor core 3A.

[0082] The fins 33 are adjacent to the first surface S1 or the second surface S2, whichever is closer to the mounting portion 131 (see FIG. 6 ). The distance between the fins 33 and the first surface S1 is shorter than the distance between the fins 33 and the second surface S2.

[0083] When viewed from the front-rear direction, the fins 33 extend radially from the inner cylindrical portion 31A. That is, the fins 33 are arranged radially around the center of rotation of the rotor core 3A.

[0084] The inner cylindrical portion 31A is connected to the outer cylindrical portion 32 via a plurality of fins 33 .

[0085] Each of the fins 33 has a plate-like shape. More specifically, each of the fins 33 has a rectangular parallelepiped shape. The longitudinal direction of each of the fins 33 is aligned with the front-rear direction but is inclined toward the rotation direction of the rotor core 3A with respect to the front-rear direction. More specifically, when viewed from the rotation axis A1 of the rotor core 3A, each of the fins 33 has a / (slash) shape.

[0086] As described above, the cavity C1 is open to both the first surface S1 and the second surface S2 of the rotor core 3A. Therefore, when the fins 33 rotate, a flow of the refrigerant (air, etc.) occurs, passing from the first surface S1 to the second surface S2 (or from the second surface S2 to the first surface S1). This facilitates circulation of the refrigerant.

[0087] For example, the refrigerant flows from the cavity C1 to the front of the rotor core 3A, and then flows to the rear of the rotor core 3A through the gaps between the teeth 62 of the stator 5 and the gaps between the stator 5 and the rotor 2. The refrigerant then returns to the cavity C1.

[0088] Third Embodiment A rotor core 3B according to a third embodiment will be described below with reference to Figures 11 to 13. The configuration of the motor 1 other than the rotor core 3B is the same as that of the first embodiment, and therefore description thereof will be omitted.

[0089] 12 shows an exploded view of three elements constituting the rotor core 3B (an element consisting of the outer cylindrical portion 32, the inner cylindrical portion 31B and the plurality of fins 33 connected to the inner cylindrical portion 31B, and other elements), but the plurality of elements constituting the rotor core 3B may be connected seamlessly. Alternatively, the plurality of elements constituting the rotor core 3B may be formed separately and joined later. In the following description, the plurality of elements constituting the rotor core 3B will be described as being connected seamlessly.

[0090] The rotor core 3B has an inner cylindrical portion 31B, an outer cylindrical portion 32, a plurality of (four in the illustrated example) first fins 33, a partition 35, and a plurality of (four in the illustrated example) second fins 36. The plurality of first fins 33 corresponds to the plurality of fins 33 in the first and second embodiments.

[0091] The inner cylindrical portion 31B has a cylindrical shape with an axial direction along the front-rear direction, and the shaft 21 (see FIG. 6) is inserted into the inner cylindrical portion 31B.

[0092] The outer cylinder 32 has a cylindrical shape with its axial direction aligned in the front-rear direction. The outer cylinder 32 is concentric with the inner cylinder 31B. The inner cylinder 31B is disposed inside the outer cylinder 32.

[0093] The partition 35 is disposed between the inner cylindrical portion 31B and the outer cylindrical portion 32 .

[0094] The partition 35 has a cylindrical shape with an axial direction along the front-rear direction. However, the front portion of the partition 35 has a relatively large outer diameter and an inner diameter, while the rear portion of the partition 35 has a relatively small outer diameter and an inner diameter.

[0095] The partition 35 has a large diameter portion 35a, an intermediate portion 35b, and a small diameter portion 35c. The large diameter portion 35a, the intermediate portion 35b, and the small diameter portion 35c are each cylindrical with an axial direction along the front-to-rear direction. The large diameter portion 35a, the intermediate portion 35b, and the small diameter portion 35c are concentric with one another. The large diameter portion 35a, the intermediate portion 35b, and the small diameter portion 35c are also concentric with the inner tube portion 31B and the outer tube portion 32.

[0096] The intermediate portion 35b protrudes rearward from the rear end of the large diameter portion 35a, and the small diameter portion 35c protrudes rearward from the rear end of the intermediate portion 35b.

[0097] The outer diameter of the small diameter portion 35c is smaller than the outer diameter of the large diameter portion 35a. The inner diameter of the small diameter portion 35c is smaller than the inner diameter of the large diameter portion 35a. The shape of the intermediate portion 35b is a truncated cone whose axial direction is along the front-rear direction, and has a through-hole at its center that penetrates in the front-rear direction. The outer and inner diameters of the intermediate portion 35b are smaller in the portions closer to the small diameter portion 35c.

[0098] The plurality of second fins 36 protrude outward from the partition 35. More specifically, the plurality of second fins 36 protrude outward from the small diameter portion 35c of the partition 35.

[0099] When viewed from the front-rear direction, the second fins 36 extend radially from the partition 35. That is, the second fins 36 are arranged radially around the center of rotation of the rotor core 3B.

[0100] When the rotor core 3B rotates, the first fins 33 cause the coolant in the first cavity C1 to flow. Similarly, when the rotor core 3B rotates, the second fins 36 cause the coolant in the second cavity C2 to flow.

[0101] The partition 35 is connected to the outer cylinder portion 32 via a plurality of second fins 36 .

[0102] The inner cylindrical portion 31B is connected to a partition 35 via a plurality of first fins 33 .

[0103] The plurality of first fins 33 protrude inward from the partition 35. More specifically, the plurality of first fins 33 protrude inward from the large diameter portion 35a of the partition 35.

[0104] In other words, the first fins 33 protrude outward from the inner cylindrical portion 31B.

[0105] When viewed from the front-rear direction, the first fins 33 extend radially from the inner cylindrical portion 31B. That is, the first fins 33 are arranged radially around the rotation center of the rotor core 3B.

[0106] The rotor core 3B has a first cavity C1 and a second cavity C2. The first cavity C1 has a configuration corresponding to the cavity C1 in the first and second embodiments.

[0107] The first cavity C1 is a space surrounded by the inner cylindrical portion 31B and the partition 35. The first cavity C1 is open to both the first surface S1 and the second surface S2 of the rotor core 3B. The first cavity C1 penetrates between the first surface S1 and the second surface S2 of the rotor core 3B.

[0108] The first cavity C1 includes a first front portion C11 between the inner cylindrical portion 31B and the large diameter portion 35a, and a first rear portion C12 between the inner cylindrical portion 31B and the intermediate portion 35b and the small diameter portion 35c. A plurality of first fins 33 are arranged in the first front portion C11. The first rear portion C12 is a space behind the first front portion C11. The first rear portion C12 is connected to the first front portion C11.

[0109] 13 (a cross section taken along the rotation axis A1), the first front portion C11 on which the plurality of first fins 33 are arranged is longer in a direction perpendicular to the front-to-rear direction than the first rear portion C12. In other words, the first front portion C11 has a larger radial width than the first rear portion C12. By providing a difference in width between the first rear portion C12 and the first front portion C11, the negative pressure in the first cavity C1 is adjusted, making it easier for the refrigerant to flow through the first cavity C1.

[0110] The second cavity C2 is a space surrounded by the partition 35 and the outer cylinder portion 32. The second cavity C2 is open to both the first surface S1 and the second surface S2 of the rotor core 3B. The second cavity C2 penetrates between the first surface S1 and the second surface S2 of the rotor core 3B.

[0111] The second cavity C2 includes a second front portion C21 between the large diameter portion 35a and the intermediate portion 35b and the outer tubular portion 32, and a second rear portion C22 between the small diameter portion 35c and the outer tubular portion 32. A plurality of second fins 36 are arranged in the second rear portion C22. The second front portion C21 is a space in front of the second rear portion C22. The second rear portion C22 is connected to the second front portion C21.

[0112] 13 (a cross section taken along the rotation axis A1), the second rear portion C22 on which the plurality of second fins 36 are arranged is longer in a direction perpendicular to the front-to-rear direction than the second front portion C21. In other words, the second rear portion C22 has a larger radial width than the second front portion C21. By providing a difference in width between the second rear portion C22 and the second front portion C21, the negative pressure in the second cavity C2 is adjusted, making it easier for the refrigerant to flow through the second cavity C2.

[0113] When viewed from the front-rear direction, the second cavity C2 is provided around the first cavity C1. In the cross section (cross section along the rotation axis A1) shown in Fig. 13, the first front portion C11 protrudes outward (in the radial direction of the rotor core 3B) compared to the first rear portion C12.

[0114] In the cross section shown in FIG. 13 (cross section along the rotation axis A1), the second rear side portion C22 protrudes inward (in the radial direction of the rotor core 3B) compared to the second front side portion C21.

[0115] The outer peripheral surface S3 of the rotor core 3B is the outer peripheral surface of the outer cylinder portion 32. The first cavity C1 and the second cavity C2 are provided inside the outer peripheral surface S3.

[0116] The front surface of the outer cylinder 32 is flush with the front surface of the inner cylinder 31B and the front surface of the partition 35. The rear surface of the outer cylinder 32 is flush with the rear surface of the inner cylinder 31B and the rear surface of the partition 35.

[0117] The first surface S1 of the rotor core 3B includes the front surface of the outer cylinder portion 32, the front surface of the inner cylinder portion 31B, and the front surface of the partition 35. The second surface S2 of the rotor core 3B includes the rear surface of the outer cylinder portion 32, the rear surface of the inner cylinder portion 31B, and the rear surface of the partition 35.

[0118] The first fins 33 are adjacent to the first surface S1 or the second surface S2, whichever is closer to the mounting portion 131 (see FIG. 6 ). The distance between the first fins 33 and the first surface S1 is shorter than the distance between the first fins 33 and the second surface S2.

[0119] The second fins 36 are adjacent to the surface (second surface S2) of the first surface S1 and the second surface S2 that is farther from the attachment portion 131 (see FIG. 6 ). The distance between the second fins 36 and the second surface S2 is shorter than the distance between the second fins 36 and the first surface S1.

[0120] Each of the first fins 33 has a plate-like shape. More specifically, each of the first fins 33 has a rectangular parallelepiped shape. The longitudinal direction of each of the first fins 33 is aligned with the front-rear direction but is inclined toward the rotation direction of the rotor core 3B with respect to the front-rear direction. More specifically, when viewed from the rotation axis A1 of the rotor core 3B, each of the first fins 33 has a shape resulting from an inverted slash ( / ) (backslash shape).

[0121] Each of the second fins 36 has a plate-like shape. More specifically, each of the second fins 36 has a rectangular parallelepiped shape. The longitudinal direction of each of the second fins 36 is aligned with the front-rear direction but is inclined toward the rotation direction of the rotor core 3B with respect to the front-rear direction. More specifically, when viewed from the rotation axis A1 of the rotor core 3B, each of the second fins 36 has a / (slash) shape.

[0122] As described above, the inclination direction of the second fins 36 is opposite to the inclination direction of the first fins 33. Therefore, when the rotor core 3B rotates, the direction of the refrigerant flow generated in the second cavity C2 by the second fins 36 is opposite to the direction of the refrigerant flow generated in the first cavity C1 by the first fins 33. For example, a forward flow occurs in the first cavity C1, and a backward flow occurs in the second cavity C2. This facilitates refrigerant circulation.

[0123] As a modification of this embodiment, the second cavity C2 may be open to only one of the first surface S1 and the second surface S2, and the first cavity C1 may be open to only one of the first surface S1 and the second surface S2.

[0124] Furthermore, as a modified example of this embodiment, the rotor core 3B may be used with the second surface S2 oriented adjacent to the attachment portion 131. That is, in the above-described example, the forward direction and the rearward direction may be reversed.

[0125] Fourth Embodiment A rotor core 3C according to a fourth embodiment will be described below with reference to Figures 14 to 16. The configuration of the motor 1 other than the rotor core 3C is the same as that of the first embodiment, and therefore description thereof will be omitted.

[0126] 15 shows an exploded view of three elements constituting the rotor core 3C (the outer cylinder portion 32, the element consisting of the inner cylinder portion 31C and the multiple connection portions 37 connected to the inner cylinder portion 31C, and other elements), but the multiple elements constituting the rotor core 3C may be connected seamlessly. Alternatively, the multiple elements constituting the rotor core 3C may be formed separately and joined later. In the following description, the multiple elements constituting the rotor core 3C will be described as being connected seamlessly.

[0127] The rotor core 3C has an inner cylindrical portion 31C, an outer cylindrical portion 32, a plurality of fins 33 (four in the illustrated example), a middle partition 35C, and a plurality of connecting portions 37 (four in the illustrated example).

[0128] The inner cylindrical portion 31C has a cylindrical shape with an axial direction along the front-rear direction, and the shaft 21 (see FIG. 6) is inserted into the inner cylindrical portion 31C.

[0129] The outer cylinder 32 has a cylindrical shape with its axial direction aligned in the front-rear direction. The outer cylinder 32 is concentric with the inner cylinder 31C. The inner cylinder 31C is disposed inside the outer cylinder 32.

[0130] The partition 35C has a cylindrical shape with its axial direction aligned in the front-to-rear direction. The partition 35C is concentric with the inner cylinder 31C and the outer cylinder 32. The partition 35C is disposed between the inner cylinder 31C and the outer cylinder 32.

[0131] The fins 33 protrude outward from the partition 35C. When viewed from the front-rear direction, the fins 33 extend radially from the partition 35C. That is, the fins 33 are arranged radially around the center of rotation of the rotor core 3C. The partition 35C is connected to the outer cylinder portion 32 via the fins 33.

[0132] Each of the plurality of connection portions 37 has a rectangular parallelepiped shape, and the longitudinal direction of each of the plurality of connection portions 37 is aligned with the front-rear direction.

[0133] The multiple connection portions 37 protrude outward from the inner cylindrical portion 31C. When viewed from the front-rear direction, the multiple connection portions 37 extend radially from the inner cylindrical portion 31C. That is, the multiple connection portions 37 are arranged radially around the center of rotation of the rotor core 3C. The inner cylindrical portion 31C is connected to the partition 35C via the multiple connection portions 37.

[0134] Each of the fins 33 has a plate-like shape. More specifically, each of the fins 33 has a rectangular parallelepiped shape. The longitudinal direction of each of the fins 33 is aligned with the front-rear direction but is inclined relative to the front-rear direction toward the rotation direction of the rotor core 3C. More specifically, when viewed from the rotation axis A1 of the rotor core 3C, each of the fins 33 has a / (slash) shape.

[0135] The rotor core 3C has a first cavity C1 and a second cavity C2. The first cavity C1 has a configuration corresponding to the cavity C1 in the first and second embodiments.

[0136] The first cavity C1 is a space surrounded by the partition 35C and the outer cylinder 32. A plurality of fins 33 are arranged in the first cavity C1.

[0137] The second cavity C2 is a space surrounded by the inner cylinder 31C and the partition 35C. The second cavity C2 is divided into a plurality of (four) spaces by a plurality of (four) connecting portions 37. No fins 33 are arranged in the second cavity C2.

[0138] When viewed from the front-rear direction, the first cavity C1 is provided around the second cavity C2.

[0139] The first cavity C1 has a larger volume than the second cavity C2.

[0140] The provision of the second cavity C2 in addition to the first cavity C1 in which the plurality of fins 33 are arranged facilitates circulation of the coolant, thereby improving the heat dissipation efficiency of the rotor core 3C.

[0141] The outer peripheral surface S3 of the rotor core 3C is the outer peripheral surface of the outer cylinder portion 32. The first cavity C1 and the second cavity C2 are provided inside the outer peripheral surface S3.

[0142] The front surface of the outer cylinder 32 is flush with the front surface of the inner cylinder 31C and the front surface of the partition 35C. The rear surface of the outer cylinder 32 is flush with the rear surface of the inner cylinder 31C and the rear surface of the partition 35C.

[0143] The first surface S1 of the rotor core 3C includes the front surface of the outer cylinder portion 32, the front surface of the inner cylinder portion 31C, and the front surface of the partition 35C. The second surface S2 of the rotor core 3C includes the rear surface of the outer cylinder portion 32, the rear surface of the inner cylinder portion 31C, and the rear surface of the partition 35C.

[0144] Each of the first cavity C1 and the second cavity C2 opens to both the first surface S1 and the second surface S2 of the rotor core 3C. Each of the first cavity C1 and the second cavity C2 penetrates between the first surface S1 and the second surface S2 of the rotor core 3C.

[0145] The fins 33 are adjacent to the first surface S1 or the second surface S2, whichever is closer to the mounting portion 131 (see FIG. 6 ). The distance between the fins 33 and the first surface S1 is shorter than the distance between the fins 33 and the second surface S2.

[0146] As a modification of this embodiment, the second cavity C2 may be open to only one of the first surface S1 and the second surface S2, and the first cavity C1 may be open to only one of the first surface S1 and the second surface S2.

[0147] (Other Modifications of Embodiments 1 to 4) Other modifications of Embodiments 1 to 4 are listed below. The following modifications may be realized in appropriate combination. Furthermore, the following modifications may be realized in appropriate combination with the above-described modifications.

[0148] The number of first fins 33 (fins 33) that the rotor core 3 (3A to 3C) has is not particularly limited, and may be one or more.

[0149] The number of second fins 36 included in the rotor core 3B is not particularly limited as long as it is one or more.

[0150] The shape of each of the first fin 33 and the second fin 36 may be a rectangular parallelepiped (flat plate) as in the first to fourth embodiments, or may be rounded.

[0151] The shape of each of the first fin 33 and the second fin 36 may be, for example, a spiral shape surrounding the inner cylinder portion 31 or the partition 35. In other words, the shape of each of the first fin 33 and the second fin 36 may be the shape of a screw thread.

[0152] The teeth 62 may protrude from the outer surface of the ring 61 toward the outside of the ring 61. Alternatively, a ring 61 may be provided on each of the inside and outside of the teeth 62.

[0153] The motor 1 (1X) may be an outer rotor type motor.

[0154] The plurality of permanent magnets 41 may be embedded in the rotor core 3 (3A to 3C). That is, the motor 1 (1X) may be a motor with an IPM structure.

[0155] The plurality of permanent magnets 41 may be wound with wire and held in the rotor core 3 (3A to 3C).

[0156] The multiple permanent magnets 41 may be arranged in an arrangement other than the Halbach arrangement.

[0157] The rotor 2 may further include a cylindrical sleeve surrounding the rotor core 3 (3A to 3C). A plurality of permanent magnets 41 may be held between the outer peripheral surface S3 of the rotor core 3 and the sleeve.

[0158] Each of the rotor core 3 (3A to 3C) and the stator core 6 may be made of a non-magnetic material.

[0159] Each of the rotor core 3 (3A to 3C) and the stator core 6 may be made of carbon fiber.

[0160] In order to circulate the refrigerant, the stator core 6 may have through holes that penetrate the stator core 6 in the front-to-rear direction. The space factor of the windings 7 may be large, and most of the gaps (slots) between the multiple teeth 62 may be occupied by the windings 7. Resin may be filled in the slots outside the windings 7. In such a case, if the stator core 6 has through holes, not only the hollow portion C1 and the gap between the rotor 2 and the stator 5 but also the through holes in the stator core 6 can be used as a circulation path for the refrigerant.

[0161] The dimensions and shapes of each component in each embodiment are merely examples and can be modified as appropriate. For example, to ensure the strength of the rotor 2 or to reduce windage loss during rotation of the rotor 2, the cavity C1 and fins 33 of the rotor core 3 (3A to 3C) may be smaller than those shown in the illustrations, or support portions may be provided on the rotor core 3 (3A to 3C). For example, at least one support portion connecting the inner cylindrical portion 31A and the inner protrusion 34 may be provided on the rear side C12 of the cavity C1 in FIG. 10. The rear side C12 may be partitioned into multiple spaces by at least one support portion when viewed from the front-to-rear direction.

[0162] (Summary) The above-described embodiments and the like disclose the following aspects.

[0163] A rotor (2) according to a first aspect includes a rotor core (3; 3A to 3C) that rotates about a rotation axis (A1) and a plurality of permanent magnets (41) held by the rotor core (3; 3A to 3C). The rotor core (3; 3A to 3C) has a circular outer peripheral surface (S3) when viewed from a direction along the rotation axis (A1), a first surface (S1) provided on one side in the direction along the rotation axis (A1), a second surface (S2) provided on the opposite side from the one side in the direction along the rotation axis (A1), a cavity (C1) provided inside the outer peripheral surface (S3) and opening at least one of the first surface (S1) and the second surface (S2), and at least one fin (33) arranged in the cavity (C1). At least one fin (33) causes a flow of the coolant present in the cavity (C1) when the rotor core (3; 3A to 3C) rotates.

[0164] According to the above configuration, the provision of at least one fin 33 improves the heat dissipation efficiency of the rotor core 3 (3A to 3C). Furthermore, compared to a case in which the at least one fin 33 is made of a separate member from the rotor core 3 (3A to 3C), the number of components of the rotor 2 can be reduced, and the number of assembly steps for the rotor 2 can be reduced.

[0165] In addition, in the rotor (2) according to the second aspect, in the first aspect, the plurality of permanent magnets (41) are arranged in a Halbach array.

[0166] According to the above configuration, even if the rotor core (3; 3A to 3C) has a hollow portion (C1) or fins (33), the possibility of the characteristics of the motor (1; 1X) changing can be reduced compared to when the rotor core (3; 3A to 3C) does not have a hollow portion (C1) or fins (33).

[0167] In addition, in the rotor (2) according to the third aspect, in the first or second aspect, the hollow portion (C1) in which at least one fin (33) is arranged has openings on both the first surface (S1) and the second surface (S2), and penetrates between the first surface (S1) and the second surface (S2) of the rotor core (3A to 3C).

[0168] According to the above configuration, the refrigerant can easily circulate through the cavity (C1).

[0169] In the rotor (2) according to the fourth aspect, the direction along the rotation axis (A1) in the third aspect is defined as the front-rear direction. The cavity (C1) includes a front portion (C11) in which at least one fin (33) is arranged, and a rear portion (C12) behind the front portion (C11).

[0170] According to the above configuration, the front side of the rotor core (3A to 3C) can be cooled intensively.

[0171] In addition, in the rotor (2) according to the fifth aspect, in the fourth aspect, in a cross section along the rotation axis (A1), the front portion (C11) on which at least one fin (33) is arranged is longer in a direction perpendicular to the fore-and-aft direction compared to the rear portion (C12).

[0172] According to the above configuration, the refrigerant can easily flow through the cavity (C1).

[0173] In addition, in a rotor (2) according to a sixth aspect, in any one of the first to fifth aspects, the cavity (C1) is a first cavity (C1). The at least one fin (33) arranged in the first cavity (C1) is at least one first fin (33). The rotor core (3B) has a second cavity (C2) that is provided inside the outer peripheral surface (S3) and has at least one of the first surface (S1) and the second surface (S2) open, and at least one second fin (36) that is arranged in the second cavity (C2) and causes a flow of refrigerant present in the second cavity (C2) when the rotor core (3B) rotates.

[0174] According to the above configuration, the heat dissipation efficiency of the rotor core (3B) is improved.

[0175] In the rotor (2) according to the seventh aspect, the direction along the rotation axis (A1) in the sixth aspect is defined as the front-rear direction. The first cavity (C1) includes a first front portion (C11) in which at least one first fin (33) is arranged and a first rear portion (C12) behind the first front portion (C11). The second cavity (C2) includes a second rear portion (C22) in which at least one second fin (36) is arranged and a second front portion (C21) in front of the second rear portion (C22).

[0176] According to the above configuration, the refrigerant can easily circulate through the first cavity (C1) and the second cavity (C2).

[0177] In addition, in the rotor (2) according to an eighth aspect, in the seventh aspect, the second cavity (C2) is provided around the first cavity (C1) when viewed from the front-to-rear direction. In a cross section taken along the rotation axis (A1), the first front portion (C11) where at least one first fin (33) is arranged protrudes outward compared to the first rear portion (C12). In a cross section taken along the rotation axis (A1), the second rear portion (C22) where at least one second fin (36) is arranged protrudes inward compared to the second front portion (C21).

[0178] According to the above configuration, the size of the rotor core (3B) can be reduced.

[0179] In addition, in the rotor (2) according to the ninth aspect, in any one of the sixth to eighth aspects, when the rotor core (3B) rotates, the direction in which the refrigerant flows through at least one first fin (33) is opposite to the direction in which the refrigerant flows through at least one second fin (36).

[0180] According to the above configuration, the refrigerant can easily circulate through the first cavity (C1) and the second cavity (C2).

[0181] In addition, in the rotor (2) according to a tenth aspect, in any one of the sixth to ninth aspects, the first cavity (C1) is open to both the first surface (S1) and the second surface (S2) and penetrates between the first surface (S1) and the second surface (S2) of the rotor core (3B). The second cavity (C2) is open to both the first surface (S1) and the second surface (S2) and penetrates between the first surface (S1) and the second surface (S2) of the rotor core (3B).

[0182] According to the above configuration, the refrigerant can easily circulate through the first cavity (C1) and the second cavity (C2).

[0183] In a rotor (2) according to an eleventh aspect, in any one of the first to fifth aspects, the cavity (C1) is a first cavity (C1). The rotor core (3C) has a second cavity (C2) that is provided inside the outer peripheral surface (S3) and has at least one of the first surface (S1) and the second surface (S2) open. The first cavity (C1), in which at least one fin (33) is arranged, has a larger volume than the second cavity (C2).

[0184] According to the above configuration, the refrigerant can easily circulate through the first cavity (C1).

[0185] In addition, in the rotor (2) according to the 12th aspect, in the 11th aspect, the first cavity (C1) in which at least one fin (33) is arranged is provided around the second cavity (C2).

[0186] According to the above configuration, the first cavity (C1) can be provided long in the circumferential direction.

[0187] In addition, in the rotor (2) according to a thirteenth aspect, in any one of the first to twelfth aspects, the rotor core (3; 3A to 3C) has a plurality of fins (33) as at least one fin (33).

[0188] According to the above configuration, the refrigerant can easily circulate through the cavity (C1).

[0189] In addition, in the rotor (2) according to the fourteenth aspect, in the thirteenth aspect, the plurality of fins (33) are arranged radially around the center of rotation of the rotor core (3; 3A to 3C).

[0190] According to the above configuration, the refrigerant can easily circulate through the cavity (C1).

[0191] The configurations other than the first aspect are not essential for the rotor (2) and can be omitted as appropriate.

[0192] A motor (1; 1X) according to a fifteenth aspect includes the rotor (2) according to any one of the first to fourteenth aspects and a stator (5). The rotor (2) rotates relative to the stator (5).

[0193] According to the above configuration, the heat dissipation efficiency of the motor (1; 1X) is improved.

[0194] In addition, the motor (1; 1X) according to a sixteenth aspect is the motor (1; 1X) of the fifteenth aspect, further comprising a drive unit (9) having an inverter circuit (91) that generates power to drive the motor (1; 1X) and a control circuit (92) that controls the inverter circuit (91), and a motor housing (13) that houses the rotor (2) and the stator (5). The drive unit (9) is in contact with the motor housing (13).

[0195] According to the above configuration, the cooling efficiency of the drive unit (9) is improved.

[0196] Furthermore, a motor (1X) according to a seventeenth aspect is the motor (1X) of the fifteenth or sixteenth aspect, further comprising a drive unit (9) having an inverter circuit (91) that generates power to drive the motor (1X) and a control circuit (92) that controls the inverter circuit (91). The stator (5) has a plurality of windings (7). The direction along the rotation axis (A1) is defined as the front-rear direction. At least a portion of the drive unit (9) is disposed in a space (SP1) surrounded by the front ends of the plurality of windings (7) or in a space (SP2) surrounded by the rear ends of the plurality of windings (7).

[0197] According to the above configuration, the cooling efficiency of the drive unit (9) is improved, and the space (SP1 or SP2) can be used effectively.

[0198] In addition, a motor (1; 1X) according to an eighteenth aspect is any one of the fifteenth to seventeenth aspects, wherein the motor (1; 1X) further includes a motor housing (13) that houses the rotor (2) and the stator (5). The motor housing (13) has a mounting portion (131) that is attached to the metal plate (8). The direction along the rotation axis (A1) is defined as the front-rear direction. Of the first surface (S1) and the second surface (S2) of the rotor core (3; 3A-3C), the surface closer to the mounting portion (131) is open to a cavity portion (C1).

[0199] According to the above configuration, heat is easily dissipated from the rotor core (3; 3A to 3C) to the metal plate (8).

[0200] In addition, in the motor (1; 1X) according to the 19th aspect, in the 18th aspect, at least one fin (33) is adjacent to the surface of the first surface (S1) and the second surface (S2) that is closer to the mounting portion (131).

[0201] According to the above configuration, heat is easily dissipated from the rotor core (3; 3A to 3C) to the metal plate (8).

[0202] In addition, in the motor (1; 1X) according to the twentieth aspect, in any one of the fifteenth to nineteenth aspects, the motor (1; 1X) is a vernier motor.

[0203] According to the above configuration, the motor (1; 1X) can generate high torque.

[0204] The configurations other than the fifteenth aspect are not essential to the motor (1; 1X) and may be omitted as appropriate.

[0205] 1; 1X Motor 2 Rotor 3; 3A to 3C Rotor core 5 Stator 7 Winding 8 Metal plate 9 Drive unit 13 Motor housing 33 Fins, first fins 36 Second fins 41 Permanent magnet 91 Inverter circuit 92 Control circuit 131 Mounting unit A1 Rotating shaft C1 Cavity, first cavity C2 Second cavity C11 Front portion, first front portion C12 Rear portion, first rear portion C21 Second front portion C22 Second rear portion S1 First surface S2 Second surface S3 Outer circumferential surface SP1 Space SP2 Space

Claims

1. A rotor comprising: a rotor core that rotates around a rotation axis; and a plurality of permanent magnets held by the rotor core, wherein the rotor core has: an outer peripheral surface that is circular when viewed in a direction along the rotation axis; a first surface provided on one side in the direction along the rotation axis; a second surface provided on the opposite side from the first side in the direction along the rotation axis; a cavity portion that is provided inside the outer peripheral surface and has at least one of the first surface and the second surface open; and at least one fin that is disposed in the cavity portion and causes a flow of refrigerant present in the cavity portion when the rotor core rotates.

2. The rotor according to claim 1, wherein the plurality of permanent magnets are arranged in a Halbach array.

3. A rotor according to claim 1 or claim 2, wherein the cavity in which the at least one fin is arranged is open to both the first surface and the second surface, and penetrates the rotor core between the first surface and the second surface.

4. The rotor according to claim 3, wherein a direction along the rotation axis is a front-rear direction, and the cavity includes a front portion in which the at least one fin is arranged, and a rear portion rearward of the front portion.

5. The rotor according to claim 4, wherein, in a cross section taken along the rotation axis, the front portion on which the at least one fin is arranged is longer in a direction perpendicular to the front-to-rear direction than the rear portion.

6. A rotor according to any one of claims 1 to 5, wherein the cavity is a first cavity, the at least one fin arranged in the first cavity is at least one first fin, and the rotor core has: a second cavity provided inside the outer circumferential surface and having at least one of the first surface and the second surface open; and at least one second fin arranged in the second cavity and causing a flow of refrigerant present in the second cavity when the rotor core rotates.

7. A rotor according to claim 6, wherein a direction along the rotation axis is defined as a front-rear direction, the first cavity includes a first front portion in which the at least one first fin is arranged and a first rear portion rearward of the first front portion, and the second cavity includes a second rear portion in which the at least one second fin is arranged and a second front portion forward of the second rear portion.

8. A rotor as described in claim 7, wherein, when viewed from the fore-and-aft direction, the second cavity is provided around the first cavity, and in a cross section taken along the rotation axis, the first front side portion on which the at least one first fin is arranged protrudes outward compared to the first rear side portion, and in the cross section taken along the rotation axis, the second rear side portion on which the at least one second fin is arranged protrudes inward compared to the second front side portion.

9. A rotor according to any one of claims 6 to 8, wherein, when the rotor core rotates, the direction in which the coolant flows due to the at least one first fin is opposite to the direction in which the coolant flows due to the at least one second fin.

10. A rotor as claimed in any one of claims 6 to 9, wherein the first cavity is open to both the first surface and the second surface, and penetrates between the first surface and the second surface of the rotor core, and the second cavity is open to both the first surface and the second surface, and penetrates between the first surface and the second surface of the rotor core.

11. A rotor according to any one of claims 1 to 5, wherein the cavity is a first cavity, the rotor core has a second cavity that is located inside the outer peripheral surface and has an opening on at least one of the first surface and the second surface, and the first cavity in which the at least one fin is arranged has a larger volume than the second cavity.

12. A rotor according to claim 11, wherein the first cavity in which the at least one fin is disposed is provided around the periphery of the second cavity.

13. A rotor according to any one of claims 1 to 12, wherein the rotor core has a plurality of fins as the at least one fin.

14. The rotor according to claim 13, wherein the plurality of fins are arranged radially around the center of rotation of the rotor core.

15. A motor comprising: a rotor according to any one of claims 1 to 14; and a stator, wherein the rotor rotates relative to the stator.

16. The motor according to claim 15, further comprising: a drive unit having an inverter circuit that generates power to drive the motor and a control circuit that controls the inverter circuit; and a motor housing that houses the rotor and the stator, wherein the drive unit is in contact with the motor housing.

17. The motor according to claim 15, further comprising a drive unit having an inverter circuit that generates power to drive the motor and a control circuit that controls the inverter circuit, wherein the stator has a plurality of windings, the direction along the rotation axis is the front-to-rear direction, and at least a portion of the drive unit is disposed in a space surrounded by the front ends of each of the plurality of windings or a space surrounded by the rear ends of each of the plurality of windings.

18. A motor as described in claim 15 or claim 17, further comprising a motor housing that houses the rotor and the stator, the motor housing having an attachment portion that is attached to a metal plate, the direction along the rotation axis being the front-to-rear direction, and the surface of the first surface and the second surface of the rotor core that is closer to the attachment portion being open to the hollow portion.

19. The motor according to claim 18, wherein the at least one fin is adjacent to one of the first and second surfaces that is closer to the mounting portion.

20. A motor according to any one of claims 15 to 19, wherein the motor is a vernier motor.

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