Spoke-type rotor and spoke-type motor

Abstract

A spoke-type rotor (20) is provided with: a rotor core (30) having a plurality of magnet holes (32) extending in the rotor radial direction; and a plurality of permanent magnets (40) respectively inserted into the plurality of magnet holes (32) and having magnetic pole surfaces (41) oriented in the rotor circumferential direction. The rotor core (30) has through holes (33A) penetrating the rotor core (30) in the rotor axial direction between magnet holes (32) adjacent to each other in the rotor circumferential direction. The through holes (33A) each have an asymmetric shape with respect to a center line (CL) extending in the rotor radial direction and passing through an intermediate point between the adjacent magnet holes (32). The magnetic resistance of a first magnetic path (35) formed between one side in the rotor circumferential direction of each through hole (33A) and a magnet hole (32) is greater than the magnetic resistance of a second magnetic path (36) formed between the other side in the rotor circumferential direction of the through hole (33A) and a magnet hole (32).

Description

Spoke rotor and spoke motor

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

[0002] Conventionally, a spoke-type rotor having multiple permanent magnets arranged in a spoke pattern is known (see, for example, Patent Document 1). The spoke-type rotor described in Patent Document 1 includes a rotor core and multiple magnets. The rotor core has an annular portion around a hole into which a rotating shaft is inserted, multiple magnetic pole pieces formed radially from the annular portion, and multiple magnet accommodating portions formed radially between adjacent magnetic pole pieces. The rotor core also has multiple first magnetic flux barrier portions formed outside the annular portion in each region between adjacent magnet accommodating portions. The magnet accommodating portions have second magnetic flux barrier portions at their ends facing the rotating shaft. The magnets are accommodated in the magnet accommodating portions so that the magnetic poles of adjacent magnets face each other in the circumferential direction of the rotor core. The rotor core also has two magnetic paths formed between the first magnetic flux barrier portion and two second magnetic flux barrier portions adjacent to the first magnetic flux barrier portion. The two magnetic paths branch in different directions from the ends of the magnetic pole pieces facing the rotating shaft toward the annular portion.

[0003] Japanese Patent Application Laid-Open No. 2015-211623

[0004] In spoke-type rotors, the dimensions of the magnet holes (corresponding to the magnet housings in Patent Document 1) that house the permanent magnets are typically set slightly larger than the permanent magnets themselves. This is to provide a clearance between the permanent magnets and the edges of the magnet holes, allowing for smooth insertion of the permanent magnets into the magnet holes. However, due to the presence of such clearance, the permanent magnets are fixed closer to one side of the rotor circumference inside the magnet holes. In this case, permanent magnets fixed closer to one side of the rotor circumference and permanent magnets fixed closer to the other side of the rotor circumference are randomly mixed. As a result, in spoke-type motors equipped with a spoke-type rotor and a stator, the rotational symmetry of the magnetic circuit formed between the two is impaired, potentially increasing cogging torque. In light of this situation, one of the objectives of the present disclosure is to reduce the cogging torque of spoke-type motors.

[0005] One aspect of the present disclosure relates to a spoke-type rotor. The spoke-type rotor includes a rotor core having a plurality of magnet holes extending in the rotor radial direction, and a plurality of permanent magnets inserted into each of the magnet holes and having magnetic pole faces facing the rotor circumferential direction. The rotor core has through holes penetrating the rotor core in the rotor axial direction between adjacent magnet holes in the rotor circumferential direction. The through holes have an asymmetric shape with respect to a center line extending in the rotor radial direction through the midpoint between the adjacent magnet holes. The magnetic reluctance of a first magnetic path formed between one side of the through holes in the rotor circumferential direction and the magnet holes is greater than the magnetic reluctance of a second magnetic path formed between the other side of the through holes in the rotor circumferential direction and the magnet holes.

[0006] Another aspect of the present disclosure relates to a spoked motor, which includes the above-described spoked rotor and a stator disposed opposite the spoked rotor.

[0007] According to the present disclosure, the cogging torque of a spoke-type motor can be reduced.

[0008] FIG. 1 is a front view showing a schematic configuration of a spoke type motor according to a first embodiment. FIG. 2 is a front view showing a schematic configuration of a spoke type rotor according to the first embodiment, with its main parts enlarged. FIG. 3 is a front view showing a schematic configuration of a spoke type rotor according to a second embodiment, with its main parts enlarged. FIG. 4 is a front view showing a schematic configuration of a spoke type rotor according to a third embodiment, with its main parts enlarged. FIG. 5 is a front view showing a schematic configuration of a spoke type rotor according to a fourth embodiment, with its main parts enlarged. FIG. 6 is a front view showing a schematic configuration of a spoke type rotor according to a fifth embodiment, with its main parts enlarged.

[0009] The following describes examples of embodiments of a spoke rotor and a spoke motor according to the present disclosure. However, the present disclosure is not limited to the examples described below. While the following description may use specific numerical values ​​and materials, other numerical values ​​and materials may be used as long as the effects of the present disclosure are achieved.

[0010] (Spoked Rotor) A spoked rotor according to the present disclosure includes a rotor core and a plurality of permanent magnets.

[0011] The rotor core has multiple magnet holes extending in the rotor radial direction. The dimensions of each magnet hole in the rotor circumferential direction may be larger than the dimensions of each permanent magnet. Each magnet hole may penetrate the rotor core in the rotor axial direction. The shape of each magnet hole is not particularly limited, and may be, for example, rectangular or trapezoidal when viewed in the rotor axial direction. The rotor core may be constructed by stacking multiple steel plates (e.g., silicon steel plates) or may be constructed of a powder magnetic core. The rotor core may have a central hole through which a shaft is inserted.

[0012] The rotor core has through holes penetrating the rotor core in the rotor axial direction between magnet holes adjacent in the rotor circumferential direction. The shape of the through holes may be the same over the entire length in the rotor axial direction, or may be different in some regions in the rotor axial direction. In the latter case, the shape of the through holes that is common over most of the rotor axial direction is interpreted as the shape of the through holes in the claims. The through holes may be voids, or may be filled with resin (e.g., heat-resistant resin such as epoxy resin). The through holes may function as flux barriers that prevent magnetic flux from the permanent magnets from short-circuiting inside the spoke-type rotor.

[0013] Multiple permanent magnets are inserted into each of the multiple magnet holes. Each permanent magnet has a magnetic pole face facing the rotor circumferential direction. Adjacent permanent magnets in the rotor circumferential direction may be arranged so that their magnetic pole faces of the same polarity face each other. This may form a single magnetic pole between adjacent permanent magnets in the rotor circumferential direction. Alternatively, magnetic poles equal in number to the number of permanent magnets may be formed on the outer periphery of the spoke-type rotor, with north and south poles alternating in the rotor circumferential direction. The dimensions of each permanent magnet in the rotor circumferential direction may be smaller than the dimensions of each magnet hole. The difference between the dimensions may be 0.05 mm or more and 0.2 mm or less. The type of each permanent magnet is not particularly limited, and may be, for example, a rare-earth magnet containing a rare-earth element such as neodymium. Each permanent magnet may be a sintered magnet. Note that in this specification, a permanent magnet housed in one magnet hole is referred to as one permanent magnet. For example, even if two permanent magnets are housed in one magnet hole, the two permanent magnets are collectively considered to be one permanent magnet.

[0014] The through holes of the rotor core have an asymmetric shape with respect to a center line that extends radially of the rotor and passes through the midpoint between adjacent magnet holes in the rotor circumferential direction. As a result of extensive research, it was discovered that if the through holes have a symmetric shape with respect to the center line, each permanent magnet is fixed within the magnet hole in a manner that is randomly biased toward one side or the other in the rotor circumferential direction due to this symmetry. Furthermore, as a result of extensive research, it was discovered that if the through holes have an asymmetric shape with respect to the center line, this asymmetry can be utilized to intentionally bias each permanent magnet within the magnet hole to one side or the other in the rotor circumferential direction.

[0015] Specifically, the magnetic reluctance of a first magnetic path formed between one side of the through hole in the rotor circumferential direction and the magnet hole is greater than the magnetic reluctance of a second magnetic path formed between the other side of the through hole in the rotor circumferential direction and the magnet hole. Each of the first magnetic path and the second magnetic path may be formed by the rotor core (more specifically, the constituent material of the rotor core) between the through hole and the magnet hole. Due to this magnitude relationship in magnetic reluctance, the permanent magnet inserted into the magnet hole is fixed inside the magnet hole closer to the other side of the rotor circumferential direction (or the first magnetic path side). That is, more of the magnetic flux of the permanent magnet in the magnet hole flows through the second magnetic path corresponding to another magnet hole located adjacent to the magnet hole on the other side of the rotor circumferential direction than through the first magnetic path corresponding to the magnet hole. Furthermore, more of the magnetic flux of the permanent magnet flows through the second magnetic path corresponding to the magnet hole than through the first magnetic path corresponding to another magnet hole located adjacent to the magnet hole on the one side of the rotor circumferential direction. Because these magnetic flux flows occur around the entire circumference of the spoke rotor, the permanent magnets inserted into the magnet holes are subjected to a stronger repulsive force toward the other side of the rotor circumference than the repulsive force toward one side of the rotor from the other permanent magnets located on either side of them in the rotor circumferential direction. This causes the permanent magnets inside each magnet hole to be fixed closer to the other side of the rotor circumference, thereby reducing the cogging torque of a spoke motor equipped with a spoke rotor according to the present disclosure.

[0016] The multiple permanent magnets may be composed of rare earth magnets. Rare earth magnets generally have high residual magnetic flux density, and a spoke motor using a spoke rotor with such a magnet can achieve high magnetic flux density. By applying the technology disclosed herein to such a high-density magnetic flux spoke motor, its effects can be fully realized. The rare earth magnet may be, for example, a neodymium magnet, but is not limited to this.

[0017] One through-hole may be provided for each magnetic pole. In this case, compared to when there are multiple through-holes, there are fewer paths through which the magnetic flux of the permanent magnets short-circuits inside the spoke rotor. This reduces the occurrence of leakage magnetic flux and improves the performance (e.g., torque density) of a spoke motor equipped with a spoke rotor.

[0018] The rotor core may have bridge portions that cross the through holes, which increases the mechanical strength of the rotor core at the locations where the through holes are provided, thereby suppressing deformation of the rotor core due to, for example, centrifugal force when the spoke-type rotor rotates.

[0019] In the rotor radial direction, the length of the first magnetic path may be greater than the length of the second magnetic path. In this case, the difference in the lengths of the magnetic paths can create the above-mentioned relationship in magnitude of magnetic resistance. Here, the length of the magnetic path refers to the length of a region in the magnetic path whose width is 1.0 to 1.5 times the minimum width. Furthermore, the width of the magnetic path refers to the dimension of the magnetic path in the rotor circumferential direction. The width of the first magnetic path may be the same as or different from the width of the second magnetic path. Note that, as long as the above-mentioned relationship in magnitude of magnetic resistance can be realized, the length of the first magnetic path may be less than the length of the second magnetic path, and the width of the first magnetic path may be smaller than the width of the second magnetic path.

[0020] In the rotor radial direction, the length of the first magnetic path may be two or more times and ten or less times the length of the second magnetic path. By making the length of the first magnetic path two or more times the length of the second magnetic path, a sufficient difference in magnetic reluctance can be generated between the two. Furthermore, by making the length of the first magnetic path ten or less times the length of the second magnetic path, the magnetic flux of the permanent magnet can be fully utilized to generate torque.

[0021] In the rotor radial direction, the length of the first and second magnetic paths may be 0.5 times or less the length of the magnet hole. In this case, the length of each magnetic path is short compared to the length of the magnet hole, that is, the area of ​​the pole face of the permanent magnet facing the through hole is small, so that the magnetic flux of the permanent magnet can be fully utilized to generate torque.

[0022] In the rotor radial direction, the length of the first magnetic flux path may be 0.1 to 0.5 times the length of the magnet hole. In the rotor radial direction, the length of the second magnetic flux path may be 0.05 to 0.05 times the length of the magnet hole and less than the length of the first magnetic flux path. By making the length of the first magnetic flux path 0.1 to 0.05 times the length of the magnet hole, and by making the length of the second magnetic flux path 0.05 to 0.05 times the length of the magnet hole, the magnetic resistance of the first magnetic flux path and the second magnetic flux path can be increased to a certain extent, and it is possible to prevent the magnetic flux of the permanent magnet from short-circuiting within the spoke-type rotor via these paths.

[0023] (Spoke Motor) A spoke motor according to the present disclosure includes the above-described spoke rotor and a stator disposed opposite the spoke rotor. The stator may be configured by laminating multiple steel plates (e.g., silicon steel plates) or may be configured with a powder magnetic core. The stator may be an integrated stator or a split stator. The stator may include a back yoke portion, multiple teeth protruding radially inward from the back yoke portion, and coils wound around each tooth portion. The coils may be wound using a distributed winding method or a concentrated winding method.

[0024] As described above, according to the present disclosure, by providing an asymmetric through-hole in the rotor core, it is possible to reduce the cogging torque of a spoke-type motor. Furthermore, according to the present disclosure, it is possible to equalize the weight balance of the spoke-type rotor.

[0025] An example of a spoked rotor and a spoked motor according to the present disclosure will be described in detail below with reference to the drawings. The components described above can be applied to the components of the example spoked rotor and spoked motor described below. The components of the example spoked rotor and spoked motor described below can be modified based on the above description. Furthermore, the matters described below may be applied to the above embodiment. Of the components of the example spoked rotor and spoked motor described below, components that are not essential to the spoked rotor and spoked motor according to the present disclosure may be omitted. Note that the diagrams shown below are schematic and do not accurately reflect the shapes and number of actual components.

[0026] Embodiment 1 Embodiment 1 of the present disclosure will be described with reference to Figures 1 and 2. Figure 1 is a front view schematically showing the configuration of a spoke type motor 10 of embodiment 1. Figure 2 is a front view schematically showing the configuration of a spoke type rotor 20 of embodiment 1, with a main portion thereof shown enlarged. As shown in Figures 1 and 2, the spoke type motor 10 of this embodiment includes the spoke type rotor 20 and a stator 50.

[0027] The spoke rotor 20 includes a rotor core 30 and a plurality of (ten in this example) permanent magnets 40 .

[0028] The rotor core 30 is a generally cylindrical element overall, and is formed by laminating multiple steel plates. The rotor core 30 has a central hole 31 through which a shaft (not shown) is inserted. The rotor core 30 has multiple (10 in this example) magnet holes 32 extending in the rotor radial direction (in FIGS. 1 and 2 , a direction extending radially from the center of the central hole 31). Each magnet hole 32 penetrates the rotor core 30 in the rotor axial direction (a direction perpendicular to the plane of the paper in FIGS. 1 and 2 ). Each magnet hole 32 is formed in a rectangular shape (more specifically, a rectangular shape with long sides roughly aligned in the rotor radial direction). The multiple magnet holes 32 are arranged rotationally symmetrically with respect to the axis of the spoke-type rotor 20 (or the center of the central hole 31). That is, in this embodiment, the multiple magnet holes 32 are arranged radially with respect to the axis of the spoke-type rotor 20 (or the center of the central hole 31), and are evenly arranged around the rotor (in Figures 1 and 2, clockwise or counterclockwise around the central hole 31).

[0029] A plurality of permanent magnets 40 are inserted into each of the plurality of magnet holes 32. Each permanent magnet 40 has a magnetic pole face 41 facing the rotor circumferential direction. Adjacent permanent magnets 40 in the rotor circumferential direction are arranged so that the magnetic pole faces 41 of the same polarity face each other. As a result, one magnetic pole is formed between adjacent permanent magnets 40 in the rotor circumferential direction. In this embodiment, ten magnetic poles are formed on the outer periphery of the spoke-type rotor 20 so that north and south poles alternate in the rotor circumferential direction. The dimensions of each permanent magnet 40 in the rotor circumferential direction are smaller than the dimensions of each magnet hole 32. Each permanent magnet 40 is made of a rare earth magnet.

[0030] The rotor core 30 has through holes 33A that penetrate the rotor core 30 in the rotor axial direction between magnet holes 32 adjacent in the rotor circumferential direction. In this embodiment, one through hole 33A is provided for each magnetic pole. That is, in this embodiment, ten through holes 33A are provided in the rotor core 30. The multiple through holes 33A are arranged rotationally symmetrically with respect to the axis of the spoke-type rotor 20 (or the center of the central hole 31). Each through hole 33A is configured as an air gap.

[0031] Each through hole 33A has an asymmetric shape with respect to a center line CL that extends in the rotor radial direction and passes through the midpoint between adjacent magnet holes 32 in the rotor circumferential direction. The magnetic resistance of the first magnetic path 35 is greater than the magnetic resistance of the second magnetic path 36. The first magnetic path 35 is formed between one side of the through hole 33A in the rotor circumferential direction (the clockwise side in FIGS. 1 and 2 ) and the magnet holes 32. The second magnetic path 36 is formed between the other side of the through hole 33A in the rotor circumferential direction (the counterclockwise side in FIGS. 1 and 2 ) and the magnet holes 32. As a result, according to the mechanism described above, each permanent magnet 40 is fixed inside each magnet hole 32, closer to the other side in the rotor circumferential direction.

[0032] In the rotor radial direction, the length of the first magnetic path 35 is greater than the length of the second magnetic path 36. More specifically, in the rotor radial direction, the length of the first magnetic path 35 is two or more times and ten or less times the length of the second magnetic path 36.

[0033] The width of the first magnetic path 35 is substantially equal to the width of the second magnetic path 36. Here, "substantially equal" does not only mean that the two widths are exactly equal, but also means that the difference between the two is within ±5%. The widths of the first magnetic path 35 and the second magnetic path 36 may be, for example, 0.2 mm or more and 0.5 mm or less.

[0034] In the rotor radial direction, the lengths of the first magnetic path 35 and the second magnetic path 36 are 0.5 times or less the length of the magnet hole 32. More specifically, in the rotor radial direction, the length of the first magnetic path 35 is 0.1 times or more and 0.5 times or less the length of the magnet hole 32, and the length of the second magnetic path 36 is 0.05 times or more the length of the magnet hole 32 but less than the length of the first magnetic path 35.

[0035] In the rotor radial direction, the outermost point of each through hole 33A is located inside the midpoint of each magnet hole 32. In other words, if a virtual circle is imagined that passes through the midpoint of each magnet hole 32 in the rotor radial direction, each through hole 33A is located entirely inside the virtual circle in the radial direction. The outline of each through hole 33A includes a circumferential side 33A-1, a first radial side 33A-2, a second radial side 33A-3, and a hypotenuse 33A-4. The circumferential side 33A-1 is a side that extends along the rotor circumferential direction. The first radial side 33A-2 is a side that extends from one end of the circumferential side 33A-1 toward the rotor radially outward along the magnet hole 32 located on one side in the rotor circumferential direction. The second radial side 33A-3 is a side that extends from the other end of the circumferential side 33A-1 toward the rotor radially outward along the magnet hole 32 located on the other side in the rotor circumferential direction. The oblique side 33A-4 is a side that connects an end of the first radial side 33A-2 and an end of the second radial side 33A-3. The first radial side 33A-2 is longer than the second radial side 33A-3. The connecting portions of the sides 33A-1, 33A-2, 33A-3, and 33A-4 are rounded, but are not limited to this.

[0036] As shown in FIG. 1 , the stator 50 is disposed opposite the spoke rotor 20. In this embodiment, the stator 50 is disposed on the outer periphery of the spoke rotor 20, facing it in the rotor radial direction. The stator 50 is a split stator formed by laminating a plurality of steel plates. That is, the stator 50 includes a plurality of split cores 51 (12 in this example), each of which is formed by laminated steel plates. Each split core 51 has a back yoke portion 51 a and teeth portions 51 b that protrude radially inward from the back yoke portion 51 a. A coil (not shown) is wound around each tooth portion 51 b. When an alternating current (e.g., three-phase alternating current) flows through the coil, a rotating magnetic field is applied from the stator 50 to the spoke rotor 20, causing the spoke rotor 20 to rotate.

[0037] Second Embodiment A second embodiment of the present disclosure will be described with reference to FIG. 3. FIG. 3 is a front view schematically illustrating the configuration of a spoke-type rotor 20 of the second embodiment, with a main portion thereof enlarged. The spoke-type motor 10 of this embodiment differs from the first embodiment in the shape of the through-holes 33B. Specifically, as shown in FIG. 3, the through-holes 33B of this embodiment are formed in a generally triangular shape. The outline of the through-holes 33B includes a circumferential side 33B-1, a radial side 33B-2, and a hypotenuse 33B-3. The circumferential side 33B-1 is a side extending along the rotor circumferential direction. The radial side 33B-2 is a side extending from one end of the circumferential side 33B-1 to the rotor radially outward along the magnet holes 32 located on one side of the rotor circumferential direction. The hypotenuse 33B-3 is a side connecting the other end of the circumferential side 33B-1 to the end of the radial side 33B-2. The connecting portions of the sides 33B-1, 33B-2, and 33B-3 are rounded, but this is not limitative. The rest of the configuration is the same as in the first embodiment.

[0038] Embodiment 3 A third embodiment of the present disclosure will be described with reference to FIG. 4. FIG. 4 is a front view schematically illustrating the configuration of a spoke-type rotor 20 according to the third embodiment, with a main portion thereof shown enlarged. The spoke-type motor 10 of this embodiment differs from the first embodiment in the shape of the through-hole 33C. Specifically, as shown in FIG. 4, the through-hole 33C of this embodiment is formed in a generally parallelogram shape. The outline of the through-hole 33C includes a first circumferential side 33C-1, a radial side 33C-2, a second circumferential side 33C-3, and a hypotenuse 33C-4. The first circumferential side 33C-1 is a side extending along the rotor circumferential direction. The radial side 33C-2 is a side extending from one end of the first circumferential side 33C-1 to the outside in the rotor radial direction, along the magnet hole 32 located on one side of the rotor circumferential direction. The second circumferential side 33C-3 is a side that extends from the end of the radial side 33C-2 along the rotor circumferential direction. The oblique side 33C-4 is a side that connects the other end of the first circumferential side 33C-1 with the end of the second circumferential side 33C-3. The connecting portions between the sides 33C-1, 33C-2, 33C-3, and 33C-4 are rounded, but this is not a limitation. The rest of the configuration is the same as in the first embodiment.

[0039] Fourth Embodiment A fourth embodiment of the present disclosure will be described with reference to FIG. 5 . FIG. 5 is a front view schematically illustrating the configuration of a spoke-type rotor 20 of the fourth embodiment, with a main portion thereof enlarged. The spoke-type motor 10 of this embodiment differs from the first embodiment in the shape of the through-holes 33D and the configuration of the rotor core 30. Specifically, as shown in FIG. 5 , the through-holes 33D of this embodiment have a trapezoidal shape with a portion (the upper left portion in FIG. 5 ) cut out. The rotor core 30 has a bridge portion 34A that crosses the through-holes 33D along the rotor circumferential direction. Note that, although the corners of the radially inner portion of the through-holes 33D (the lower trapezoidal portion in the enlarged view of the main portion in FIG. 5 ) and the radially outer portion of the through-holes 33D (the upper trapezoidal portion in the enlarged view of the main portion in FIG. 5 ) are rounded, this is not a limitation. The rest of the configuration is the same as the first embodiment.

[0040] Fifth Embodiment A fifth embodiment of the present disclosure will be described with reference to FIG. 6 . FIG. 6 is a front view schematically illustrating the configuration of a spoke-type rotor 20 of the fifth embodiment, with a main portion thereof enlarged. The spoke-type motor 10 of this embodiment differs from the first embodiment in the shape of the through-holes 33E and the configuration of the rotor core 30. Specifically, as shown in FIG. 6 , the through-holes 33E of this embodiment have a trapezoidal shape with a portion (the upper left portion in FIG. 6 ) cut out. The rotor core 30 has a bridge portion 34B that crosses the through-holes 33E along the rotor radial direction. Note that, although the corners of the through-holes 33E on one side of the rotor circumferential direction (the trapezoidal portion on the right side in the enlarged view of the main portion in FIG. 6 ) and the other side of the rotor circumferential direction (the trapezoidal portion on the left side in the enlarged view of the main portion in FIG. 6 ) are rounded, this is not a limitation. The rest of the configuration is the same as the first embodiment.

[0041] <<Notes>> The above description of the embodiment discloses the following techniques.

[0042] (Technology 1) A spoke-type rotor of Technology 1 includes a rotor core having a plurality of magnet holes extending in the rotor radial direction, and a plurality of permanent magnets inserted into each of the plurality of magnet holes and having magnetic pole faces facing the rotor circumferential direction. The rotor core has through holes penetrating the rotor core in the rotor axial direction between adjacent magnet holes in the rotor circumferential direction. The through holes have an asymmetric shape with respect to a center line extending in the rotor radial direction through the midpoint between adjacent magnet holes. The magnetic reluctance of a first magnetic path formed between one side of the through holes in the rotor circumferential direction and the magnet holes is greater than the magnetic reluctance of a second magnetic path formed between the other side of the through holes in the rotor circumferential direction and the magnet holes.

[0043] (Technology 2) In the spoke rotor of Technology 2, the plurality of permanent magnets in the spoke rotor described in Technology 1 are made of rare earth magnets.

[0044] (Technology 3) In the spoke rotor of Technology 3, in the spoke rotor according to Technology 1 or 2, one through hole is provided for each magnetic pole.

[0045] (Technology 4) In the spoke type rotor of Technology 4, in the spoke type rotor according to any one of Technologies 1 to 3, the rotor core has bridge portions that cross the through holes.

[0046] (Technology 5) In the spoke rotor of Technology 5, in the spoke rotor according to any one of Technologies 1 to 4, the length of the first magnetic flux path is greater than the length of the second magnetic flux path in the rotor radial direction.

[0047] (Technology 6) In the spoke rotor of Technology 6, in the spoke rotor described in Technology 5, the length of the first magnetic path in the rotor radial direction is at least two times and at most ten times the length of the second magnetic path.

[0048] (Technology 7) In the spoke rotor of Technology 7, in the spoke rotor described in any one of Technologies 1 to 6, the lengths of the first magnetic path and the second magnetic path in the rotor radial direction are 0.5 times or less the length of the magnet hole.

[0049] (Technology 8) In a spoke rotor of Technology 8, the length of the first magnetic path in the rotor radial direction is 0.1 to 0.5 times the length of the magnet holes in the spoke rotor described in Technology 7. Also, the length of the second magnetic path in the rotor radial direction is 0.05 to 0.05 times the length of the magnet holes but less than the length of the first magnetic path.

[0050] (Technology 9) A spoke motor of Technology 9 includes the spoke rotor according to any one of Technology 1 to Technology 8, and a stator disposed opposite the spoke rotor.

[0051] The present disclosure can be used in spoked rotors and spoked motors.

[0052] REFERENCE SIGNS LIST 10 Spoke type motor 20 Spoke type rotor 30 Rotor core 31 Center hole 32 Magnet hole 33A Through hole 33A-1 Circumferential side 33A-2 First radial side 33A-3 Second radial side 33A-4 Oblique side 33B Through hole 33B-1 Circumferential side 33B-2 Radial side 33B-3 Oblique side 33C Through hole 33C-1 First circumferential side 33C-2 Radial side 33C-3 Second circumferential side 33C-4 Oblique side 33D Through hole 33E Through hole 34A Bridge portion 34B Bridge portion 35 First magnetic path 36 Second magnetic path 40 Permanent magnet 41 Magnetic pole surface 50 Stator 51 Split core 51a Back yoke portion 51b Teeth part CL center line

Claims

1. A spoke-type rotor comprising: a rotor core having a plurality of magnet holes extending in the radial direction of the rotor; and a plurality of permanent magnets inserted into each of the plurality of magnet holes and having magnetic pole faces facing the circumferential direction of the rotor, wherein the rotor core has through holes penetrating the rotor core in the axial direction of the rotor between the magnet holes adjacent to each other in the circumferential direction of the rotor, the through holes have an asymmetrical shape with respect to a center line extending in the radial direction of the rotor passing through an intermediate point between the adjacent magnet holes, and a magnetic resistance of a first magnetic path formed between one side in the circumferential direction of the rotor of the through hole and the magnet hole is larger than a magnetic resistance of a second magnetic path formed between the other side in the circumferential direction of the rotor of the through hole and the magnet hole.

2. The spoke-type rotor according to claim 1, wherein the plurality of permanent magnets are made of rare earth magnets.

3. The spoke-type rotor according to claim 1 or 2, wherein the through holes are provided one by one for each magnetic pole.

4. The spoke-type rotor according to claim 1 or 2, wherein the rotor core has a bridge portion crossing the through hole.

5. The spoke-type rotor according to claim 1 or 2, wherein in the radial direction of the rotor, a length of the first magnetic path is larger than a length of the second magnetic path.

6. The spoke-type rotor according to claim 5, wherein in the radial direction of the rotor, the length of the first magnetic path is 2 times or more and 10 times or less the length of the second magnetic path.

7. The spoke-type rotor according to claim 1 or 2, wherein in the radial direction of the rotor, lengths of the first magnetic path and the second magnetic path are 0.5 times or less the length of the magnet hole.

8. The spoke-type rotor according to claim 7, wherein in the radial direction of the rotor, the length of the first magnetic path is 0.1 times or more and 0.5 times or less the length of the magnet hole, and in the radial direction of the rotor, the length of the second magnetic path is 0.05 times or more and less than the length of the first magnetic path.

9. A spoke-type motor comprising: the spoke-type rotor according to claim 1 or 2; and a stator provided facing the spoke-type rotor.

Images