Rotor, axial gap motor, and motor

Abstract

To provide a technique for reducing iron loss and suppressing an increase in mechanical loss in a rotor for a motor.SOLUTION: A rotor for a motor includes a rotor core portion made of ceramic, a magnet disposed inside or on an outer surface of the rotor core portion, and a shaft portion connected to the rotor core portion and made of ceramic.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a rotor, an axial gap motor, and a motor. [Background technology]

[0002] BACKGROUND ART Rotors for motors have been known in the past (for example, Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-40996 [Patent Document 2] International Publication No. 2018 / 147052 Summary of the Invention [Problem to be solved by the invention]

[0004] However, even with the prior art such as Patent Documents 1 and 2, there is still room for improvement in the technology for reducing iron loss and suppressing an increase in mechanical loss in a motor rotor.

[0005] An object of the present invention is to provide a technique for reducing iron loss and suppressing an increase in mechanical loss in a rotor for a motor. [Means for solving the problem]

[0006] The present invention has been made to solve at least part of the above-mentioned problems, and can be realized in the following aspects.

[0007] (1) According to one aspect of the present invention, there is provided a rotor for a motor, the rotor including a rotor core made of ceramic, a magnet disposed inside or on an outer surface of the rotor core, and a shaft connected to the rotor core and made of ceramic.

[0008] With this configuration, the rotor core and shaft are made of ceramic, which reduces iron loss in the rotor core and other components compared to materials such as electromagnetic steel sheets and iron. Furthermore, ceramics that form the shaft have a smaller thermal expansion coefficient than metals, which reduces changes in size of the shaft due to temperature changes. This reduces the amount of change in friction between the shaft and a portion that rotatably supports it, even when the temperature of the shaft changes. This reduces increases in mechanical loss in the rotor due to temperature changes.

[0009] (2) The rotor of the above embodiment may further include a magnetic portion provided in the rotor core and made of a soft magnetic material, and the magnet may form a magnetic circuit passing through the magnetic portion. According to this configuration, the rotor is provided with a magnetic portion through which the magnetic circuit formed by the magnet passes. The rotor core is made of ceramic and has relatively low iron loss, which can improve the ratio of output to input to the motor, i.e., motor efficiency. Furthermore, a rotor with relatively low iron loss and mechanical loss is less likely to heat up. This suppresses temperature rise in the magnetic portion, thereby suppressing performance degradation of the magnetic portion due to temperature rise.

[0010] (3) In the rotor of the above aspect, the magnets may be arranged in the rotor core portion so as to form a Halbach array. According to this configuration, the magnets are arranged in the rotor core portion so as to form a Halbach array. The rotor core portion is made of ceramic and has relatively small iron loss, so the magnetic field strength generated by the magnets in a specific direction can be further strengthened. This can further improve the efficiency of the motor.

[0011] (4) In the rotor of the above aspect, the rotor core portion may have a substantially circular plate shape, the shaft portion may be connected to the center of the rotor core portion so that its axial direction is perpendicular to the main surface of the rotor core portion, and the magnet may be arranged in the rotor core portion so that its longitudinal direction is perpendicular to the axial direction of the shaft portion. According to this configuration, the shaft portion is connected to the center of the rotor core portion so that its axial direction is perpendicular to the main surface of the rotor core portion, and the magnet is arranged in the rotor core portion so that its longitudinal direction is perpendicular to the axial direction of the shaft portion. As a result, a motor including the rotor of the above aspect can be an axial gap motor in which the main direction of the magnetic flux in the magnetic circuit formed by the magnet is along the axial direction of the shaft portion. The rotor core portion of the rotor of the above aspect is made of ceramic with relatively low iron loss, which further improves the efficiency of the axial gap motor.

[0012] (5) In the rotor of the above aspect, the rotor core may include two plate-shaped members having a substantially circular shape, the magnets being arranged on one of a pair of main surfaces of each of the two plate-shaped members, and the shaft may be connected to the two plate-shaped members so that the magnets arranged on each of the two plate-shaped members face each other. According to this configuration, in the rotor, the magnets are arranged on the opposing main surfaces of the pair of main surfaces of each of the two plate-shaped members connected by the shaft in the rotor core. This allows a motor including the rotor of the above aspect to be an axial gap motor in which the main direction of the magnetic flux in the magnetic circuit formed by the magnets is along the axial direction of the shaft. The rotor core of the rotor of the above aspect is made of ceramic with relatively low iron loss, further improving the efficiency of the axial gap motor.

[0013] (6) According to another aspect of the present invention, there is provided an axial gap motor. This axial gap motor includes the rotor described above and a motor stator having windings for generating a magnetic field, the magnetic field being formed so that the direction of magnetic flux is along the axial direction of the shaft portion. With this configuration, in the axial gap motor, the rotor core portion and the shaft portion are formed from ceramic, so that iron loss generated in the rotor core portion and the like can be made smaller than with electromagnetic steel sheet or iron. This can further improve the efficiency of the axial gap motor.

[0014] (7) According to yet another aspect of the present invention, a motor is provided. The motor includes the rotor described above and a motor stator disposed outside the rotor core and having windings for generating a magnetic field. With this configuration, the motor includes a rotor core and a shaft formed from ceramic, so that iron loss and mechanical loss in the rotor are relatively small. This suppresses temperature rise in the rotor, thereby suppressing temperature rise in the entire motor. Therefore, it is possible to suppress a decrease in motor efficiency due to temperature rise.

[0015] The present invention can be realized in various forms, for example, in the form of a device including a rotor, a device including an axial gap motor, a device including a motor, a method for manufacturing a rotor, a method for manufacturing an axial gap motor, a method for manufacturing a motor, a computer program that causes a computer to execute the manufacture of a rotor, etc. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a cross-sectional view of a motor including a rotor according to a first embodiment. [Figure 2] FIG. 2 is a perspective view of a rotor member according to the first embodiment. [Figure 3] FIG. 2 is a perspective view of a rotor according to the first embodiment. [Figure 4] FIG. 2 is a cross-sectional view of the rotor of the first embodiment. [Figure 5] 5A to 5C are diagrams illustrating evaluation results regarding the rotor of the first embodiment. [Figure 6] FIG. 10 is a cross-sectional view of a rotor of a comparative example. [Figure 7] FIG. 10 is a cross-sectional view of a motor including a rotor according to a second embodiment. [Figure 8] FIG. 10 is a perspective view of a rotor member included in a rotor according to a second embodiment. [Figure 9] FIG. 10 is a perspective view of a rotor according to a second embodiment. [Figure 10] FIG. 6 is a cross-sectional view of a rotor according to a second embodiment. [Figure 11] FIG. 6 is a diagram showing a magnetic circuit formed in a rotor of a second embodiment. [Figure 12] 10A and 10B are diagrams illustrating evaluation results regarding the rotor of the second embodiment. [Figure 13] FIG. 10 is a cross-sectional view of a rotor of a comparative example. [Figure 14] FIG. 10 is a cross-sectional view of a rotor according to a third embodiment. [Figure 15] 10A and 10B are diagrams illustrating evaluation results regarding the rotor of the third embodiment. [Figure 16] FIG. 10 is a cross-sectional view of an axial gap motor according to a fourth embodiment. [Figure 17] FIG. 17 is a cross-sectional view taken along line AA in FIG. 16. [Figure 18] 10A and 10B are diagrams illustrating evaluation results regarding the rotor of the fourth embodiment. [Figure 19] FIG. 10 is a cross-sectional view of an axial gap motor according to a fifth embodiment. [Figure 20] FIG. 10 is a cross-sectional view of a rotor according to a sixth embodiment. [Figure 21] FIG. 3 is a cross-sectional view of a first modified example of the rotor of the first embodiment. [Figure 22] FIG. 4 is a cross-sectional view of a second modified example of the rotor of the first embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0017] First Embodiment 1 is a cross-sectional view of a motor including a rotor according to a first embodiment. A rotor 10 according to this embodiment is used in a motor 1 that outputs rotational torque when supplied with electric power. The motor 1 includes the rotor 10, a stator 20, and a motor case 30. The rotor 10 is provided on a central axis C1 of the motor 1 so as to be rotatable about the central axis C1.

[0018] Fig. 2 is a perspective view of a rotor member of this embodiment. Fig. 3 is a perspective view of the rotor of this embodiment. Fig. 4 is a cross-sectional view of the rotor of this embodiment. The rotor 10 includes a rotor core portion 110 formed of ceramic, magnets 120 arranged on the outer surface of the rotor core portion 110, and a shaft portion 130 connected to the rotor core portion 110 and formed of ceramic. In the rotor 10 of this embodiment, the rotor member 100 including the rotor core portion 110 and the shaft portion 130 is formed from a single ceramic member.

[0019] 2, the rotor core portion 110 has a generally cylindrical shape. The support portions 111 are recessed portions formed on a side surface 112 of the rotor core portion 110. In this embodiment, four support portions 111 are formed on the side surface 112 of the rotor core portion 110, lined up along the circumferential direction of the rotor core portion 110.

[0020] The magnet 120 is supported by a support portion 111 of the rotor core portion 110. In this embodiment, the magnet 120 is supported by the rotor core portion 110 by being fitted into the support portion 111 of the rotor core portion 110, i.e., a recessed portion formed on the side surface 112 of the rotor core portion 110. In other words, the motor 1 of this embodiment is a so-called SPM motor in which the magnet 120 is mounted on the surface of the rotor core portion 110. The magnet 120 may be fixed to the recessed portion of the support portion 111 with an adhesive (resin), or may be fixed (for example, welded) directly to the rotor core portion 110 without using an adhesive.

[0021] The shaft portion 130 has two shaft portions 131 and 132. Each of the two shaft portions 131 and 132 is formed so as to protrude from each of two end faces 113 and 114 of the rotor core portion 110, which has a substantially cylindrical shape (see FIG. 1). Each of the shaft portions 131 and 132 has a substantially rod shape with its longitudinal direction aligned with the central axis C10 of the rotor 10 (see FIG. 3). The outer diameter of each of the shaft portions 131 and 132 is smaller than the outer diameter of the rotor core portion 110. The end of each of the shaft portions 131 and 132 opposite to the end connected to the rotor core portion 110 is exposed to the outside of the motor case 30, which will be described later (see FIG. 1).

[0022] The rotor member 100 (the rotor core portion 110 and the shaft portion 130) of this embodiment is formed of ceramic. The ceramic forming the rotor member 100 of this embodiment is at least one of oxide, carbide, nitride, and boride. Specifically, the rotor member 100 is formed of at least one of oxide-based ceramics such as alumina (Al2O3), silica (SiO2), titanium oxide (TiO2), zirconia (ZrO2), and magnesia (MgO); carbide-based ceramics such as silicon carbide (SiC), boron carbide (B4C), titanium carbide (TiC), and chromium carbide (CrC); nitride-based ceramics such as aluminum nitride (AlN), silicon nitride (Si3N4), titanium nitride (TiN), and sialon (SiAlON); and boride-based ceramics such as zirconium boride (ZrB2). The material forming the rotor member 100 is identified using X-ray diffraction (XRD) and energy dispersive X-ray analysis (EDS). The rotor core portion 110 and the shaft portion 130 of this embodiment are formed from zirconium boride.

[0023] The stator 20 has a stator core portion 210 and a winding 220 (see FIG. 1). The stator 20 is disposed outside the rotor core portion 110 and is fixed to the motor case 30, which will be described later, inside the motor case 30. The stator core portion 210 is formed to have a substantially cylindrical shape and has a plurality of protrusions 211 on the inside. The stator core portion 210 is formed by stacking a plurality of electromagnetic steel plates.

[0024] The windings 220 are conductor wires covered with an insulator, and are wound around each of the plurality of protrusions 211 of the stator core portion 210. When electricity supplied from outside the motor 1 flows through the windings 220, the windings 220 generate a magnetic field.

[0025] The motor case 30 is a hollow member that houses the rotor 10 and the stator 20. Two bearings 310, 320 are provided in the motor case 30. The bearings 310, 320 are provided on two opposing bracket portions 301, 302 of the motor case 30. One of the two shaft portions 131, 132, the shaft portion 131, is inserted through the bearing 310, and the other of the two shaft portions 131, 132, the shaft portion 132, is inserted through the bearing 320. In this way, the rotor 10 is rotatably supported by the motor case 30.

[0026] Next, an example of a manufacturing method of the rotor 10 of this embodiment will be described. In the manufacturing method of the rotor 10, first, predetermined amounts of ceramic particles and sintering aid as main raw materials are weighed. Next, the weighed materials are charged into a ball mill together with ethanol, and pulverized and mixed for a predetermined time to prepare a slurry. Next, the prepared slurry is extrusion-molded to form an extruded body having a generally cylindrical shape. Next, the extruded body is processed to form a portion that will become the shaft portion 130, a portion that will become the support portion 111, and the like, to prepare a processed body having the shape of the rotor member 100. Next, the processed body is fired by heating under predetermined conditions to prepare a fired body. Finally, the magnet 120 is fixed to the support portion 111 formed on the fired body, thereby preparing the rotor 10. Note that the manufacturing method of the rotor 10 shown here is merely an example, and the manufacturing method is not limited to this.

[0027] Next, an evaluation test of the rotor of this embodiment will be described. In this evaluation test, five types of motors (hereinafter referred to as "samples") were fabricated, each differing in rotor material, rotor structure, the presence or absence of a magnetic part or its material, or motor structure, which are used in SPM motors, and the "iron loss" and "rotation efficiency" were evaluated for each of the five samples.

[0028] FIG. 5 is a diagram illustrating the evaluation results for the rotor of this embodiment. Of the five types of samples used in this evaluation test, Samples 1 to 3 are motors equipped with rotors manufactured by a method similar to the manufacturing method for rotor 10 of this embodiment. For each of Samples 1 to 3, the material of the ceramic particles used as the main raw material was selected so that the rotor core and shaft had the composition of the "material" of the "rotor" shown in FIG. 5. Sample 4 is a motor equipped with a rotor manufactured by stacking multiple electromagnetic steel plates. Sample 5 is a motor equipped with a rotor manufactured by extruding and processing epoxy resin.

[0029] The "structure" of the "rotor" shown in Figure 5 indicates, for each of Samples 1 to 5, either a structure in which the rotor core portion and the shaft portion are formed separately ("separate") or a structure in which they are formed integrally ("integrated"). The "magnetic portion" shown in Figure 5 indicates, for each of Samples 1 to 5, whether or not a magnetic portion is provided in the rotor core portion. Samples 1 to 5 do not have a magnetic portion.

[0030] 5 shows the structure of the sample. Each of Samples 1 to 3, whose rotors are made of ceramic, has the same structure as Motor 1 of this embodiment, that is, an SPM.

[0031] FIG. 6 is a cross-sectional view of a rotor of a comparative example. In this evaluation test, the "iron loss" and "rotation efficiency" shown in FIG. 5 were measured for a motor including a rotor 10c of a comparative example (hereinafter simply referred to as the "SPM motor of the comparative example"). As shown in FIG. 6, the rotor 10c of the comparative example includes a rotor core portion 110c, a magnet 120c, and a shaft portion 130c connected to the rotor core portion 110c. In the rotor 10c of the comparative example, the rotor core portion 110c and the shaft portion 130c are formed from laminated electromagnetic steel plates, and the magnet 120c is mounted on a surface 112c of the rotor core portion 110c.

[0032] The "iron loss" shown in Figure 5 was calculated using the method of JIS C 4034-2-1. Specifically, the loss of each motor was measured using the method of JIS C 4034-2-1 for the motors equipped with each of Samples 1 to 5 and the SPM motor of the comparative example. The iron loss of each motor was then calculated by subtracting the copper loss, calculated using the current flowing through the motor, and the mechanical loss, calculated from friction, etc., from the measured loss. For the calculated iron loss values ​​of each motor, the magnitude of the iron loss of each of Samples 1 to 5 relative to the SPM motor of the comparative example was designated as the "iron loss" for each of Samples 1 to 5, and the magnitude of the "iron loss" was classified into the following symbols, A and B. A: 95% or more and less than 100% of the motor in the comparison example B: Less than 95% of the motor of the comparative example

[0033] The "rotational efficiency" shown in Figure 5 indicates the ratio of output to input in a motor, i.e., the efficiency of the motor. "Rotational efficiency" was measured by first measuring the output of a motor equipped with each of Samples 1 to 5 and an SPM motor of the comparative example when rotated at a predetermined rotation speed. The degree of difference in the magnitude of the output measured for a motor equipped with each of Samples 1 to 5 relative to the output measured for the SPM motor of the comparative example was taken as "rotational efficiency" and was classified into the following symbols A, B, and C. A: Improved by more than 1% compared to the comparison motor B: Same as the comparison motor or less than 1% improvement C: Lower than the motor used in the comparison example

[0034] In terms of "iron loss" shown in Figure 5, it was confirmed that Samples 1 to 3, whose rotor "material" is ceramic, exhibited better performance than Sample 4, whose rotor "material" was electromagnetic steel sheet. Sample 4, which was made of electromagnetic steel sheet, was prone to iron loss such as hysteresis loss and eddy current loss. On the other hand, Samples 1 to 3, which were made of ceramic, were less likely to exhibit these losses. This suppresses heat generation in the rotor, making Samples 1 to 3 less likely to experience temperature increases. Therefore, it is possible to suppress a decrease in motor efficiency due to temperature increases. In terms of "rotation efficiency" shown in Figure 5, it was confirmed that Samples 1 to 3, whose "material" was ceramic, exhibited better performance than Sample 5, whose "material" was epoxy resin, and exhibited performance at least as good as Sample 4, whose "material" was electromagnetic steel sheet.

[0035] According to the rotor 10 of this embodiment described above, the rotor core 110 and the shaft 130 are formed from ceramic, which reduces iron loss generated in the rotor core 110 and other components compared to materials such as electromagnetic steel sheets and iron. Furthermore, the ceramic that forms the shaft 130 has a smaller thermal expansion coefficient than metal, which reduces changes in size of the shaft 130 due to temperature changes. This reduces the amount of change in friction between the shaft 130 and the bearings 310 and 320 that rotatably support the shaft 130, even when the temperature of the shaft 130 changes, thereby suppressing increases in mechanical loss due to temperature changes. This improves the efficiency of the motor 1.

[0036] Furthermore, according to the motor 1 of this embodiment, the motor 1 includes the rotor core 110 and the shaft 130 made of ceramic, which reduces iron loss and mechanical loss in the rotor 10. This suppresses temperature rise in the rotor 10, thereby suppressing temperature rise in the entire motor 1. This suppresses a decrease in efficiency of the motor 1 due to temperature rise.

[0037] Second Embodiment 7 is a cross-sectional view of a motor including a rotor according to the second embodiment. The rotor according to the second embodiment differs from the rotor according to the first embodiment (FIG. 1) in that it includes a magnetic portion.

[0038] Similar to the rotor 10 of the first embodiment, the rotor 40 of the second embodiment is provided in a motor 2 including a stator 20 and a motor case 30. The rotor 40 is provided on the central axis C2 of the motor 2 so as to be rotatable about the central axis C2.

[0039] Fig. 8 is a perspective view of a rotor member provided in the rotor of this embodiment. Fig. 9 is a perspective view of the rotor of this embodiment. Fig. 10 is a cross-sectional view of the rotor of this embodiment. The rotor 40 includes a rotor core portion 410 made of ceramic, a magnet 420 arranged inside the rotor core portion 410, a shaft portion 130 connected to the rotor core portion 410 and made of ceramic, and a magnetic portion 440 provided in the rotor core portion 410 and made of a soft magnetic material. In the rotor 40 of this embodiment, the rotor member 400 including the rotor core portion 410 and the shaft portion 130 is formed from a single ceramic member.

[0040] As shown in FIG. 8, the rotor core portion 410 has a substantially cylindrical shape. Of the two end faces 411, 412 of the rotor core portion 410 having a substantially cylindrical shape, one end face 411 is formed with an insertion hole 413 for inserting a magnet 420 and an insertion hole 414 for inserting a magnetic portion 440. In this embodiment, the insertion hole 413 is formed so that the opening portion in the end face 411 has an annular shape, as shown in FIG. 10. The insertion hole 414 is formed so that the opening portion in the end face 411 is located inside the opening portion of the insertion hole 413. In this embodiment, ten insertion holes 414 are formed so that one magnetic portion 440 is positioned across two adjacent magnets 420 out of the ten magnets 420 inserted into the insertion holes 413 (see FIG. 10). The two shaft portions 131, 132 of the shaft portion 130 are formed so as to protrude longitudinally from the two end faces 411, 412 of the rotor core portion 410, which has a substantially cylindrical shape, along the central axis C40 of the rotor 40 (see FIG. 9).

[0041] The magnets 420 are mounted on the rotor core portion 410 by being inserted into the insertion holes 413 of the rotor core portion 410. That is, the motor 2 of this embodiment is a so-called IPM motor in which the magnets 420 are mounted inside the rotor core portion 410. In this embodiment, as shown in FIG. 10, ten magnets 420 are inserted into the insertion holes 413 and arranged around the entire circumference of the rotor core portion 410. As shown in FIG. 7, each of the ten magnets 420 is arranged so that its longitudinal direction is approximately parallel to the axial direction of the shaft portion 130 (the direction of the central axis C2 of the motor 2). Note that in FIG. 7, to avoid cluttering the drawing, only two magnets 420 that appear in the cross section are shown.

[0042] The ceramic forming the rotor member 400 (the rotor core portion 410 and the shaft portion 130) of this embodiment is at least one of oxide, carbide, nitride, and boride. The rotor core portion 410 and the shaft portion 130 of this embodiment are formed from a mixture of silicon nitride and titanium nitride.

[0043] The magnetic part 440 is mounted on the rotor core part 410 by being inserted into the insertion hole 414 of the rotor core part 110 (see FIGS. 7, 9, and 10). Materials that can be used to form the magnetic part 440 include iron (Fe), cobalt (Co), nickel (Ni), nanocrystalline soft magnetic materials having nano-sized crystals in an amorphous alloy, electromagnetic steel sheets, and soft magnetic ceramics such as ferrite (Fe2O3). The magnetic part 440 of this embodiment is formed from a nanocrystalline soft magnetic material.

[0044] Fig. 11 is a diagram showing a magnetic circuit formed in the rotor of this embodiment. For convenience of illustration, Fig. 11 shows only the cross section of rotor 40 also shown in Fig. 10. In this embodiment, magnet 420 forms a magnetic circuit Mgc that passes through magnetic portion 440.

[0045] Next, an example of a manufacturing method for the rotor 40 of this embodiment will be described. The manufacturing method for the rotor 40 is a method similar to the manufacturing method for the rotor 10 of the first embodiment. The manufacturing method for the rotor 40 differs from the manufacturing method for the rotor 10 in that portions that will become the insertion holes 413, 414 are processed in a molded extrusion molded body to produce a processed molded body having the shape of the rotor member 400, and the magnet 420 and the magnetic portion 440 are inserted into the insertion holes 413, 414 formed in the sintered molded body, respectively. Note that the manufacturing method for the rotor 40 shown here is an example and is not limited to this manufacturing method.

[0046] Next, we will explain the evaluation test of the rotor of this embodiment. In this evaluation test, five types of samples were produced that differed in any of the rotor material, rotor structure, magnetic part material, and motor structure used in the IPM motor, and the "iron loss" and "rotation efficiency" were evaluated for each of the five types of samples.

[0047] FIG. 12 is a diagram illustrating the evaluation results for the rotor of this embodiment. Each of the five types of samples (samples 6 to 10) used in this evaluation test is a motor equipped with a rotor manufactured by a method similar to the manufacturing method for rotor 40 of this embodiment. For each of samples 6 to 10, the material of the ceramic particles as the main raw material was selected so that the rotor core and shaft had the composition of the "material" of the "rotor" shown in FIG. 12. The volume ratio of Si2N4 to TiN in sample 7 and the volume ratio of Al2O3 to ZrO2 in sample 10 were both 7:3.

[0048] The "structure" of the "rotor" shown in Figure 12 indicates, for each of Samples 6 to 10, either a structure in which the rotor core portion and shaft portion are formed separately ("separate") or a structure in which they are formed integrally ("integrated"). For each of Samples 6 to 10, the rotor core portion and shaft portion are formed integrally. The "magnetic portion" shown in Figure 12 indicates the material of the magnetic portion provided in the rotor core portion for each of Samples 6 to 10. Sample 6 is provided with a magnetic portion formed from ferrite, and Sample 7 is provided with a magnetic portion formed from a nanocrystalline soft magnetic material. Samples 8 to 10 are provided with a magnetic portion formed from an electromagnetic steel sheet.

[0049] The "structure" of the "motor" shown in Fig. 12 indicates the structure of the sample. Each of Samples 6 to 10 has the same structure as the motor 2 of this embodiment, that is, an IPM.

[0050] FIG. 13 is a cross-sectional view of a rotor of a comparative example. In this evaluation test, the "iron loss" and "rotation efficiency" shown in FIG. 12 each show the results of a comparison with a motor including a rotor 40c of a comparative example (hereinafter simply referred to as the "IPM motor of the comparative example"). As shown in FIG. 13, the rotor 40c of the comparative example includes a rotor core portion 410c, a magnet 420c disposed inside the rotor core portion 410c, and a shaft portion 430c connected to the rotor core portion 410c. In the rotor 40c of the comparative example, the rotor core portion 410c and the shaft portion 430c are formed from laminated electromagnetic steel plates, and the magnet 420c is mounted by being inserted into an insertion hole 413c formed in the rotor core portion 410c.

[0051] As in the first embodiment, the "iron loss" and "rotation efficiency" shown in FIG. 12 were evaluated using the same threshold values ​​as in the first embodiment, with the comparative IPM motor including the comparative rotor 40c as the evaluation standard. Regarding the "iron loss" shown in FIG. 12, Samples 6 to 10, whose rotors are made of ceramic, were confirmed to exhibit superior performance to the comparative IPM motor including the rotor 40c made of electromagnetic steel sheet. Samples 6 to 10, which are made of ceramic, are less likely to generate iron loss such as hysteresis loss and eddy current loss, and heat generation in the rotor is suppressed, making it less likely for the temperature to rise. Therefore, a decrease in motor efficiency due to temperature rise can be suppressed. Furthermore, because each of Samples 6 to 10 has a magnetic portion in the rotor core, the magnetic circuit formed by the magnet preferentially passes through the magnetic portion in the rotor core. As a result, each of Samples 6 to 10 exhibits even lower iron loss in the rotor core than the comparative IPM motor without a magnetic section, which is thought to suppress temperature rise in the rotor core and thus suppress performance degradation of the magnetic section due to temperature rise. Therefore, by providing a magnetic section, motor efficiency can be further improved. The "Rotation Efficiency" shown in Figure 12 confirms that Samples 6 to 10, which use ceramic as the "Material," exhibit superior performance to the comparative IPM motor with a rotor 40c made of electromagnetic steel sheet.

[0052] According to the rotor 40 of this embodiment described above, the rotor core 410 and the shaft 130 are made of ceramic, which allows for smaller iron loss in the rotor core 410 and the like than in electromagnetic steel sheets, iron, and the like. Furthermore, since the ceramic that forms the shaft 130 has a smaller thermal expansion coefficient than metal, even if the temperature of the shaft 130 changes, the amount of change in friction between the shaft 130 and the bearings 310 and 320 that rotatably support the shaft 130 is small, thereby suppressing an increase in mechanical loss due to temperature changes. This allows for improved efficiency of the motor 2.

[0053] Furthermore, according to the rotor 40 of this embodiment, the rotor 40 is provided with a magnetic portion 440 through which the magnetic circuit Mgc formed by the magnets 420 passes. The rotor core 410 is made of ceramic and has relatively small iron loss, which can improve the ratio of output to input to the motor 2, i.e., the efficiency of the motor. Furthermore, the rotor 40, which has relatively small iron loss and mechanical loss, is less likely to increase in temperature. This also suppresses the temperature increase in the magnetic portion 440, which can suppress performance degradation of the magnetic portion 440 due to temperature increase. Therefore, by providing the magnetic portion 440, the efficiency of the motor 2 can be further improved.

[0054] <Third embodiment> Fig. 14 is a cross-sectional view of the rotor of the third embodiment. The rotor of the third embodiment differs from the rotor of the second embodiment (Fig. 10) in that the magnets are arranged in a Halbach array.

[0055] Similar to the rotor 40 of the second embodiment, the rotor 50 of the third embodiment is provided in a motor including a stator 20 and a motor case 30. The rotor 50 includes a rotor core portion 510, a plurality of magnets 520, a shaft portion 130, and a magnetic portion 540.

[0056] The rotor core portion 510 has a generally cylindrical shape, similar to the rotor core portion 410 of the second embodiment. One of the two end faces of the generally cylindrical rotor core portion 510 is formed with an insertion hole 513 for inserting multiple magnets 520 and an insertion hole 514 for inserting a magnetic portion 540. As shown in FIG. 14 , each of the insertion holes 513 is formed so that a cross section perpendicular to the central axis C50 of the rotor 50 has an annular shape. As shown in FIG. 14 , the insertion hole 514 into which the magnetic portion 540 is inserted is formed inside the insertion hole 513 into which the multiple magnets 520 are inserted.

[0057] The multiple magnets 520 are arranged in the rotor core portion 510 in a Halbach array. Specifically, the multiple magnets 520 inserted into the insertion holes 513 of the rotor core portion 510 are arranged around the entire circumference of the rotor core portion 510, and the magnetic pole direction of each of the multiple magnets 520 is determined so that the magnetic field strength is maximized on the outside of the rotor core portion 510. In Fig. 14, the magnetic pole direction of each of the multiple magnets 520 is indicated by a solid arrow Mp.

[0058] The magnetic portion 540 is provided in the rotor core portion 510 and is made of a soft magnetic material. In this embodiment, the magnetic portion 540 is made of a nanocrystalline soft magnetic material. The magnetic portion 540 is supported by the rotor core portion 510 by being inserted into an insertion hole 514 formed in the rotor core portion 510.

[0059] Next, an evaluation test of the rotor of this embodiment will be described. In this evaluation test, three types of motor samples with magnets in a Halbach array were fabricated, and the "iron loss" and "rotation efficiency" of each of the three samples were evaluated in the same manner as in the evaluation test of the rotor of the first embodiment.

[0060] FIG. 15 is a diagram illustrating the evaluation results for the rotor of this embodiment. The three types of samples (samples 11 to 13) used in this evaluation test are motors equipped with rotors manufactured by a method similar to the manufacturing method for rotor 10 of the first embodiment, with magnets arranged in a Halbach array. Each of samples 11 to 13 is provided with a magnetic portion formed of a nanocrystalline soft magnetic material. The "iron loss" and "rotation efficiency" shown in FIG. 15 show the results of a comparison of each of the three types of samples with a motor (not shown) equipped with a rotor in which the rotor "material" is an electromagnetic steel plate and multiple magnets are arranged in a Halbach array in the rotor core (hereinafter simply referred to as a "comparative example Halbach array motor"), evaluated using the same method as the evaluation test of the first embodiment.

[0061] As shown in Figure 15, Samples 11 to 13, in which the "rotor" material is ceramic, were confirmed to exhibit superior performance in both "iron loss" and "rotation efficiency" compared to the comparative motor with a Halbach array. In this way, it was confirmed that a motor in which magnets are arranged in a Halbach array exhibits superior performance by forming the rotor core and shaft of the rotor from ceramic.

[0062] According to the rotor 50 of this embodiment described above, the rotor core portion 510 and the shaft portion 130 are formed of ceramic, which makes it possible to reduce iron loss generated in the rotor core portion 510 and the like compared to electromagnetic steel sheet, iron, etc. Furthermore, since the ceramic forming the shaft portion 130 has a smaller thermal expansion coefficient than metal, it is possible to suppress an increase in mechanical loss in the rotor 50. This makes it possible to improve the efficiency of the motor of this embodiment.

[0063] Furthermore, according to the rotor 50 of this embodiment, the magnets 520 are arranged in the rotor core portion 510 in a Halbach array. The rotor core portion 510 is made of ceramic and has relatively small iron loss, so the strength of the magnetic field formed by the magnets 520 can be further strengthened outside the rotor core portion 510. This can further improve the efficiency of the motor of this embodiment.

[0064] <Fourth embodiment> Fig. 16 is a cross-sectional view of an axial gap motor of the fourth embodiment. Fig. 17 is a cross-sectional view taken along line AA in Fig. 16. The rotor of the fourth embodiment differs from the rotor of the first embodiment (Fig. 1) in the shape of the rotor core and the position of the magnets in the rotor core.

[0065] The rotor 60 of this embodiment is used in a motor 4 that outputs rotational torque when power is supplied. The motor 4 includes the rotor 60, a motor stator 70, and a motor case 30. The rotor 60 is provided on a central axis C4 of the motor 4 so as to be rotatable about the central axis C4.

[0066] The rotor 60 includes a rotor core portion 610 made of ceramic, a magnet 620 arranged in the rotor core portion 610, a shaft portion 630 made of ceramic and connected to the rotor core portion 610, and a magnetic portion 640. In the rotor 60 of this embodiment, the rotor core portion 610 and the shaft portion 630 are formed from a single ceramic member. However, the rotor core portion 610 and the shaft portion 630 may be formed from separate members and joined together.

[0067] The rotor core portion 610 has a generally circular plate shape. The generally circular plate-shaped rotor core portion 610 has a plurality of through holes 613 formed therein, each having an opening in two main surfaces 611, 612. A magnet 620 is disposed in each of the plurality of through holes 613. An insertion hole 614 for inserting a magnetic portion 640 is formed in one main surface 611 of the two main surfaces 611, 612 of the rotor core portion 610.

[0068] The magnet 620 is mounted on the rotor core portion 610 by being inserted into the through-hole 613 of the rotor core portion 610. In this embodiment, as shown in FIG. 16 , the magnet 620 is arranged in the rotor core portion 610 so that its longitudinal direction is perpendicular to the axial direction of the shaft portion 630 (the direction of the central axis C4 of the motor 4). Here, "perpendicular" includes not only a case where the magnet 620 intersects at a right angle in the strict sense, but also a case where the magnet 620 intersects at an apparent right angle. The magnet 620 has exposed surfaces 621 and 622 that are exposed from the two main surfaces 611 and 612 of the rotor core portion 610, respectively.

[0069] The shaft portion 630 has two shaft portions 631, 632 connected to the center of the rotor core portion 610 so that the axial direction of each shaft portion 630 is perpendicular to the main surfaces 611, 612 of the rotor core portion 610. The two shaft portions 631, 632 are formed so as to protrude from the two main surfaces 611, 612 of the rotor core portion 610, respectively (see FIG. 16 ). The shaft portion 631 is rotatably supported by a bearing 310 of the motor case 30. The shaft portion 632 is rotatably supported by a bearing 320 of the motor case 30.

[0070] The magnetic portion 640 is provided in the rotor core portion 610 and is made of a soft magnetic material. In this embodiment, the magnetic portion 640 is made of a nanocrystalline soft magnetic material. The magnetic portion 640 is mounted on the rotor core portion 610 by being inserted into an insertion hole 614 formed in the rotor core portion 610.

[0071] The stator 70 has a stator core portion 710 and a winding 720 for generating a magnetic field. The motor 4 of this embodiment includes two stators 70, which are arranged so as to face the exposed surfaces 621 and 622 of the magnet 620, respectively.

[0072] The stator core portion 710 has a plurality of columnar portions 711 formed so that the axial direction of each columnar portion 711 is aligned with the central axis C4 of the motor 4. The stator core portion 710 is formed by laminating a plurality of electromagnetic steel plates.

[0073] The winding 720 is a conductor wire coated with an insulator. The winding 720 is wound around each of the multiple columnar portions 711 of the stator core portion 710. That is, in this embodiment, the winding axis of the winding 720 is approximately parallel to the central axis C4 of the motor 4. When electricity supplied from outside the motor 4 flows through the winding 720, it generates a magnetic field.

[0074] In the motor 4 of this embodiment, the first stator 70, the rotor 60, and the second stator 70 are arranged in this order along the direction of the central axis C4. As a result, in the motor 4, a magnetic flux for rotating the rotor 60 is generated mainly along the direction of the central axis C4. In other words, the motor 4 is a so-called axial gap motor in which the gap between the rotor 60 and the two stators 70 is defined along the direction of the central axis C4.

[0075] Next, an evaluation test of the rotor of this embodiment will be described. In this evaluation test, four types of axial gap motor samples were fabricated, and the "iron loss" and "rotation efficiency" of each of the four samples were evaluated in the same manner as in the evaluation test of the rotor of the first embodiment.

[0076] FIG. 18 is a diagram illustrating the evaluation results for the rotor of this embodiment. Samples 14 to 17 used in this evaluation test are axial gap motors equipped with rotors manufactured by a method similar to the manufacturing method for rotor 10 of the first embodiment. Each of Samples 14 to 17 is provided with a magnetic portion formed from a nanocrystalline soft magnetic material. The "iron loss" and "rotation efficiency" shown in FIG. 18 show the results of a comparison of each of the four samples with an axial gap motor (not shown) (hereinafter simply referred to as the "comparative axial gap motor") that has the same structure as the axial gap motor of this embodiment shown in FIGS. 16 and 17 and is equipped with a rotor in which a rotor core portion and a shaft portion are formed from laminated electromagnetic steel sheets, evaluated using the same method as the evaluation test of the first embodiment.

[0077] As shown in Fig. 18, it was confirmed that Samples 14 to 17, in which the "material" of the "rotor" is ceramic, exhibited superior performance in both "iron loss" and "rotation efficiency" to the axial gap motor of the comparative example. In this way, it was confirmed that an axial gap motor in which the rotor core and shaft of the rotor are made of ceramic exhibits superior performance.

[0078] According to the rotor 60 of this embodiment described above, the rotor core 610 and the shaft 630 are made of ceramic, so that the iron loss generated by the rotor core 610 can be made smaller than that of electromagnetic steel sheet, iron, etc. Furthermore, the ceramic that forms the shaft 630 has a smaller thermal expansion coefficient than metal, so that an increase in mechanical loss in the rotor 60 can be suppressed. This can improve the efficiency of the motor 4.

[0079] Furthermore, according to the rotor 60 of this embodiment, the shaft portion 630 is connected to the center of the rotor core portion 610 so that its axial direction is perpendicular to the main surfaces 611, 612 of the rotor core portion 610. The magnet 620 is arranged in the rotor core portion 610 so that its longitudinal direction is perpendicular to the axial direction of the shaft portion 630. This allows the motor 4 including the rotor 60 to be an axial gap motor in which the main direction of the magnetic flux in the magnetic circuit formed by the magnet 620 is along the axial direction of the shaft portion 630. The rotor core portion 610 of the motor 4 is made of ceramic with relatively low iron loss, which further improves the efficiency of the motor 4, which is an axial gap motor.

[0080] Fifth Embodiment 19 is a cross-sectional view of an axial gap motor according to Embodiment 5. The rotor according to Embodiment 5 differs from the rotor according to Embodiment 1 (FIG. 1) in the shape of the rotor core and the position of the magnets in the rotor core.

[0081] The rotor 80 of this embodiment is used in a motor 5 that outputs rotational torque when power is supplied. The motor 5 includes the rotor 80, a motor stator 90, and a motor case 30. The rotor 80 is provided on a central axis C5 of the motor 5 so as to be rotatable about the central axis C5.

[0082] The rotor 80 includes a rotor core portion 810 made of ceramic, a magnet 820 arranged in the rotor core portion 810, a shaft portion 830 made of ceramic and connected to the rotor core portion 810, and a magnetic portion 840. In the rotor 80 of this embodiment, the rotor core portion 810 and the shaft portion 830 are formed from a single ceramic member. However, the rotor core portion 810 and the shaft portion 830 may be formed from separate members and joined together.

[0083] The rotor core portion 810 has two plate-shaped members 811 and 812, each having a substantially circular shape. The plate-shaped member 811 has a pair of main surfaces 811a and 811b. The plate-shaped member 812 has a pair of main surfaces 812a and 812b. As shown in FIG. 19 , the two plate-shaped members 811 and 812 are arranged such that one main surface 811a of the plate-shaped member 811 faces one main surface 812a of the plate-shaped member 812. Insertion holes 811d and 812d for inserting the magnetic portion 840 are formed in side surfaces 811c and 812c of the two plate-shaped members 811 and 812, respectively.

[0084] In the plate-shaped member 811, the magnet 820 is disposed on one principal surface 811a of a pair of principal surfaces 811a, 811b. In the plate-shaped member 812, the magnet 820 is disposed on one principal surface 812a of a pair of principal surfaces 812a, 812b. As a result, in the motor 4 of this embodiment, the magnets 820 provided on each of the two plate-shaped members 811, 812 are disposed to face each other.

[0085] The shaft portion 830 connects the two plate-shaped members 811, 812 of the rotor core portion 810 so that the magnets 820 arranged on each of the two plate-shaped members 811, 812 face each other. Specifically, the shaft portion 830 has a connecting portion 831 and two protrusions 832, 833. The connecting portion 831 connects the two plate-shaped members 811, 812 of the rotor core portion 810. The protrusion 832 is formed to protrude from the main surface 811b of the plate-shaped member 811. The protrusion 832 is rotatably supported by the bearing 310 of the motor case 30. The protrusion 833 is formed to protrude from the main surface 812b of the plate-shaped member 812. The protrusion 833 is rotatably supported by the bearing 320 of the motor case 30.

[0086] The magnetic part 840 is provided in the rotor core part 810 and is made of a soft magnetic material. In this embodiment, the magnetic part 840 is made of a nanocrystalline soft magnetic material. The magnetic part 840 is mounted on the rotor core part 810 by being inserted into the insertion holes 811d, 812d formed in the rotor core part 810.

[0087] The stator 90 has a stator core 910 and windings 920 for generating a magnetic field. In the motor 5 of this embodiment, the stator 90 is fixed to the motor case 30 so as to be disposed between the magnets 820 supported by the two plate-like members 811 and 812 of the rotor core 810.

[0088] The stator core portion 910 has a columnar portion 911 formed so that its axial direction is aligned with the central axis C5 of the motor 5. The stator core portion 910 is formed by laminating a plurality of electromagnetic steel plates.

[0089] The winding 920 is a conductor wire coated with an insulator. The winding 920 is wound around each of the multiple columnar portions 911 of the stator core 910. That is, the winding axis of the winding 920 in this embodiment is approximately parallel to the central axis C5 of the motor 5. When electricity supplied from outside the motor 5 flows through the winding 920, it generates a magnetic field.

[0090] In the motor 5 of this embodiment, the plate-shaped member 811 of the rotor core 810, the stator 90, and the plate-shaped member 812 of the rotor core 810 are arranged in this order along the direction of the central axis C5. As a result, in the motor 5, a magnetic flux for rotating the rotor 80 is generated mainly along the direction of the central axis C5. In other words, the motor 5 is a so-called axial gap motor in which the gap between the two rotors 80 and the stator 90 is defined along the direction of the central axis C5.

[0091] According to the rotor 80 of this embodiment described above, the rotor core portion 810 and the shaft portion 830 are formed of ceramic, so that the iron loss generated by the rotor core portion 810 and the like can be made smaller than that of electromagnetic steel sheet, iron, etc. Furthermore, the ceramic forming the shaft portion 830 has a smaller thermal expansion coefficient than metal, so that an increase in mechanical loss in the rotor 80 can be suppressed. This allows the efficiency of the motor 5 to be improved.

[0092] Furthermore, according to rotor 80 of this embodiment, in rotor 80, magnet 820 is arranged on one main surface 811a of a pair of main surfaces 811a, 811b of plate-shaped member 811 of rotor core portion 810, and magnet 820 is arranged on one main surface 812a of a pair of main surfaces 812a, 812b of plate-shaped member 812 of rotor core portion 810. Magnet 820 of plate-shaped member 811 and magnet 820 of plate-shaped member 812 are arranged to face each other, and winding 920, whose winding axis is approximately parallel to central axis C5 of motor 5, is arranged between magnet 820 of plate-shaped member 811 and magnet 820 of plate-shaped member 812. As a result, motor 5 including rotor 80 can be an axial gap motor in which the main direction of magnetic flux in a magnetic circuit formed by magnet 820 is along the axial direction of shaft portion 830. The rotor core 810 of the motor 5 is made of ceramic with a relatively small iron loss, which can further improve the efficiency of the motor 5, which is an axial gap motor.

[0093] Sixth Embodiment 20 is a cross-sectional view of a rotor including the rotor of the sixth embodiment. The rotor of the sixth embodiment differs from the rotor of the second embodiment (FIG. 2) in that it does not include a magnetic portion.

[0094] Like the rotor 40 of the second embodiment, the rotor 40 of the sixth embodiment is provided in a motor including a stator 20 and a motor case 30. The rotor 40 includes a rotor core portion 410 made of ceramic, a magnet 420 disposed inside the rotor core portion 410, and a shaft portion 130 connected to the rotor core portion 410 and made of ceramic.

[0095] According to the rotor 40 of this embodiment described above, the rotor core 410 and the shaft 130 are made of ceramic, so that the iron loss generated by the rotor core 410 and the like can be made smaller than that of electromagnetic steel sheet, iron, etc. Furthermore, the ceramic that forms the shaft 130 has a smaller thermal expansion coefficient than metal, so that an increase in mechanical loss in the rotor 40 can be suppressed.

[0096] <Modification of this embodiment> The present invention is not limited to the above-described embodiment, and can be embodied in various forms without departing from the spirit of the invention. For example, the following modifications are also possible.

[0097] [Variation 1] In the first embodiment, the rotor core and shaft of the rotor are formed of zirconium boride. In the second embodiment, the rotor core and shaft are formed of a mixture of silicon nitride and titanium nitride. However, the ceramic forming the rotor core and shaft is not limited to this. As described above, the ceramic forming the rotor core and shaft is preferably at least one of oxide, carbide, nitride, and boride, but is not limited to these. When the ceramic forming the rotor core and shaft is at least one of oxide, carbide, and nitride, the rotor becomes relatively lightweight and relatively strong. Therefore, not only is breakage during use suppressed, but the rotor is easily manufactured due to excellent processability during manufacturing.

[0098] [Variation 2] In the rotor with Halbach-arranged magnets of the third embodiment, and the axial gap motors of the fourth and fifth embodiments, the rotor includes a magnetic section made of a nanocrystalline soft magnetic material. While the magnetic section is not required, the magnetic section allows the magnetic circuit formed by the magnets to pass preferentially through the magnetic section. This further reduces iron loss in the rotor core, further suppressing temperature rise in the rotor core and further suppressing performance degradation in the magnetic section.

[0099] [Variation 3] In the above-described embodiment, the rotor member including the rotor core portion and the shaft portion is formed from a single ceramic member. However, the relationship between the rotor core portion and the shaft portion is not limited to this.

[0100] Fig. 21 is a cross-sectional view of a first modified example of the rotor of the first embodiment. In the rotor 10 shown in Fig. 21, the rotor core portion 110 and the shaft portion 130 are separate members. Specifically, the rotor core portion 110 has a through hole 115 on the central axis C10 of the rotor 10. The shaft portion 130 is inserted into the through hole 115 and fixed to the rotor core portion 110. Even in the rotor 10 configured in this manner, the rotor core portion 110 and the shaft portion 130 are made of ceramic, so that iron loss can be reduced and an increase in mechanical loss can be suppressed.

[0101] Fig. 22 is a cross-sectional view of a second modified example of the rotor of the first embodiment. In the rotor 10 shown in Fig. 22, the rotor core portion 110 and the shaft portions 131 and 132 are separate members. The shaft portions 131 and 132 are connected to two end faces 113 and 114 of the rotor core portion 110, which has a substantially cylindrical shape, respectively, by an adhesive or the like (not shown). Even in the rotor 10 configured in this manner, the rotor core portion 110 and the shaft portion 130 are made of ceramic, so that iron loss can be reduced and an increase in mechanical loss can be suppressed.

[0102] This aspect has been described above based on embodiments and modifications. However, the above-described embodiments are intended to facilitate understanding of this aspect and are not intended to limit this aspect. This aspect may be modified or improved without departing from the spirit and scope of the claims, and equivalents thereof are included in this aspect. Furthermore, if a technical feature is not described as essential in this specification, it may be deleted as appropriate.

[0103] <Application example 1> A rotor for a motor, comprising: a rotor core portion formed of ceramic; a magnet disposed inside or on the outer surface of the rotor core; a shaft portion connected to the rotor core portion and formed of ceramic, A rotor characterized by: <Application example 2> The rotor according to Application Example 1 further comprises: a magnetic portion provided in the rotor core portion and formed of a soft magnetic material; The magnet forms a magnetic circuit passing through the magnetic portion. A rotor characterized by: <Application example 3> The rotor according to Application Example 1 or Application Example 2, The magnets are arranged in the rotor core portion in a Halbach array. A rotor characterized by: <Application Example 4> The rotor according to any one of Application Examples 1 to 3, The rotor core portion has a substantially circular plate shape, the shaft portion is connected to the center of the rotor core portion so that its axial direction is perpendicular to a main surface of the rotor core portion, The magnet is disposed in the rotor core portion so that the longitudinal direction of the magnet is perpendicular to the axial direction of the shaft portion. A rotor characterized by: <Application example 5> The rotor according to any one of Application Examples 1 to 4, The rotor core portion has two plate-shaped members each having a substantially circular shape, the magnet is disposed on one of a pair of main surfaces of each of the two plate-like members, The shaft portion is connected to the two plate-like members so that the magnets arranged on each of the two plate-like members face each other. A rotor characterized by: <Application Example 6> An axial gap motor, The rotor according to any one of Application Examples 1 to 5, a stator for the motor having windings for creating a magnetic field; The magnetic field is formed so that the direction of the magnetic flux is along the axial direction of the shaft portion. An axial gap motor characterized by: <Application Example 7> A motor, The rotor according to any one of Application Examples 1 to 5, a stator for the motor, the stator being disposed outside the rotor core and having a winding for generating a magnetic field; A motor characterized by: [Explanation of symbols]

[0104] 1,2,3,4,5...Motor 10, 40, 50, 60, 80... rotor 20, 70, 90... Stator 110, 410, 510, 610, 810...Rotor core 130, 630, 830...shaft section 120, 420, 520, 620, 820...Magnet 440,540,640,840...Magnetic part 220, 720, 920...winding 811, 812... Plate-shaped members 811a, 811b, 812a, 812b...main surface Mgc...magnetic circuit

Claims

1. A rotor for a motor, comprising: a rotor core portion formed of ceramic; a magnet disposed inside or on the outer surface of the rotor core; a shaft portion connected to the rotor core portion and formed of ceramic, A rotor characterized by:

2. The rotor according to claim 1 further comprises: a magnetic portion provided in the rotor core portion and formed of a soft magnetic material; The magnet forms a magnetic circuit passing through the magnetic portion. A rotor characterized by:

3. 3. The rotor according to claim 1 or 2, The magnets are arranged in the rotor core portion in a Halbach array. A rotor characterized by:

4. 3. The rotor according to claim 1 or 2, The rotor core portion has a substantially circular plate shape, the shaft portion is connected to the center of the rotor core portion so that its axial direction is perpendicular to a main surface of the rotor core portion, The magnet is disposed in the rotor core portion so that the longitudinal direction of the magnet is perpendicular to the axial direction of the shaft portion. A rotor characterized by:

5. 3. The rotor according to claim 1 or 2, The rotor core portion has two plate-shaped members each having a substantially circular shape, the magnet is disposed on one of a pair of main surfaces of each of the two plate-like members, the shaft portion is connected to the two plate-like members such that the magnets disposed on the two plate-like members face each other; A rotor characterized by:

6. An axial gap motor, The rotor according to claim 1 or 2; a stator for the motor having windings for creating a magnetic field; The magnetic field is formed so that the direction of the magnetic flux is along the axial direction of the shaft portion. An axial gap motor characterized by:

7. A motor, The rotor according to claim 1 or 2; a stator for the motor, the stator being disposed outside the rotor core and having a winding for generating a magnetic field; A motor characterized by:

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