Motor, air conditioner, and method for manufacturing motor

Abstract

A motor (241) has a rotor (52). The rotor (52) has a shaft (61), a disk (62), an annular plastic magnet (63), and a resin mold (64). The disk (62) has a center hole (62a) through which the shaft (61) penetrates. The resin mold (64) fixes the shaft (61), the disk (62), and the plastic magnet (63).

Description

Motor, air conditioning device, and method for manufacturing motor

[0001] The present disclosure relates to a motor, an air conditioning device equipped with the motor, and a method for manufacturing the motor.

[0002] The indoor unit of an air conditioner disclosed in Patent Document 1 (JP 2005-069580 A) has an indoor fan motor that rotates a crossflow fan. The indoor fan motor has a stator and a rotor. The rotor is an outer rotor that is fixed to the end plate of the crossflow fan. The rotor is made of, for example, a resin material mixed with magnetic powder, and the magnetic powder forms eight magnetic poles on the outer edge of the rotor.

[0003] The shaft, located at the center of the rotor, is inserted into end plates that extend perpendicular to the shaft's direction of extension. The flat portion of the rotor extends from the outer edge of the rotor along the end plate. The flat portion is molded integrally with the outer edge. The flat portion is fixed to the end plate.

[0004] The outer edge of the rotor, which has magnetic poles, is fixed to the shaft via a flat portion and an end plate. The shaft must be inserted into the end plate, and the flat portion must contact the end plate. Because there are crossovers in the outer diameter of each of these intervening components, it is difficult to accurately achieve the relative angle and position between the shaft and rotor as designed. This can result in vibration or damage when the rotor rotates.

[0005] Furthermore, if the flat surface portion is made of a resin material mixed with magnetic powder, the rotor may be damaged due to lack of durability.

[0006] A motor according to a first aspect of the present invention has a rotor. The rotor has a shaft, a disk, an annular plastic magnet, and a resin mold. The disk has a center hole through which the shaft passes. The resin mold fixes the shaft, the disk, and the plastic magnet.

[0007] According to this configuration, the rotor has a disk, and therefore the group of parts consisting of the shaft and the disk is in close contact with the resin mold over a wide area, allowing the resin mold to firmly fix the shaft.

[0008] A motor according to a second aspect is the motor according to the first aspect, wherein the shaft is fixed to the disk by being press-fitted into the central hole.

[0009] With this configuration, the shaft and the disk are firmly fixed to each other by press fitting, which also results in a strong fixation between the resin mold and the shaft.

[0010] A motor according to a third aspect is the motor according to the first or second aspect, wherein the entire disk is disposed in a resin mold.

[0011] With this configuration, the entire surface area of ​​the disk comes into contact with the resin mold, and therefore the resin mold firmly fixes the disk.

[0012] A motor according to a fourth aspect is the motor according to any one of the first to third aspects, wherein the disk has a plurality of through holes in addition to the central hole.

[0013] According to this configuration, the resin mold fills the through holes, which makes it possible to more firmly fix the resin mold to the disk.

[0014] A motor according to a fifth aspect is the motor according to any one of the first to fourth aspects, wherein the plastic magnet has an axis and two end faces that are spaced apart in the direction of the axis, and the resin mold is in contact with at least one of the two end faces.

[0015] According to this configuration, the resin mold fixes the end face of the plastic magnet, and therefore the resin mold fixes the shaft, the disk, and the plastic magnet.

[0016] A motor according to a sixth aspect is the motor according to any one of the first to fifth aspects, further comprising a stator. The stator interacts magnetically with the rotor. The rotor is an outer rotor having a larger outer diameter than the stator.

[0017] In this configuration, the rotor is an outer rotor. Therefore, the distance from the group of parts consisting of the shaft and the disk to the plastic magnet is long. The transmission of force over this long distance is carried out by the resin mold.

[0018] A motor according to a seventh aspect is the motor according to any one of the first to sixth aspects, wherein the plastic magnet is made of a resin material containing a magnetic substance.

[0019] According to this configuration, the plastic magnet is made of a magnetic material and a resin material. Therefore, the magnetic material can magnetically interact with the stator. In addition, the resin material makes it easy to mold the plastic magnet.

[0020] A motor according to an eighth aspect is the motor according to any one of the first to seventh aspects, wherein the resin mold is made of a thermosetting resin or a thermoplastic resin.

[0021] According to this configuration, the resin mold is made of a thermosetting resin or a thermoplastic resin, which makes it easy to process the resin mold.

[0022] A motor according to a ninth aspect is the motor according to any one of the first to eighth aspects, wherein the linear expansion coefficient of the plastic magnet is 3.5×10 －５ ( / °C). The linear expansion coefficient of the resin mold is 3.5 × 10 －５ ( / °C).

[0023] With this configuration, the linear expansion coefficient of the resin mold is smaller than that of the plastic magnet, and therefore the resin mold is less likely to change volume with temperature changes, making it less susceptible to damage such as cracks.

[0024] An air conditioning apparatus according to a tenth aspect includes a motor and a crossflow fan. The motor is the motor according to any one of the first to ninth aspects. The crossflow fan is fixed to a rotor of the motor.

[0025] According to this configuration, the rotor of the motor mounted in the air conditioner has a disk, and therefore the shaft and the resin mold are firmly fixed together, improving the reliability of the motor.

[0026] The manufacturing method of an eleventh aspect is for manufacturing a motor. In the manufacturing method, a shaft, a circular plate having a center hole, an annular plastic magnet, and a resin material are prepared. Next, the shaft and the circular plate are fixed by press-fitting the shaft into the center hole. Next, both the shaft and the plastic magnet are held in a mold or a jig fixed to the mold. Next, a resin material is injected or poured into the internal space of the mold. Next, the resin material is hardened to form a resin mold that fixes the shaft, the circular plate, and the plastic magnet.

[0027] According to this manufacturing method, the disk in the rotor of the motor is firmly fixed to the resin mold, thereby improving the reliability of the motor.

[0028] A manufacturing method according to a twelfth aspect is the manufacturing method according to the eleventh aspect, in which after the resin mold is formed, the entire disk is placed in the resin mold.

[0029] According to this manufacturing method, the entire surface area of ​​the disk comes into contact with the resin mold, and therefore the resin mold firmly fixes the disk.

[0030] A manufacturing method according to a thirteenth aspect is the manufacturing method according to the eleventh or twelfth aspect, wherein the plastic magnet has an axis and two end faces. The two end faces are spaced apart in the direction in which the axis extends. After the resin mold is formed, the resin mold is in contact with at least one of the two end faces.

[0031] According to this manufacturing method, the resin mold fixes the end faces of the plastic magnet, and therefore the resin mold fixes the shaft, the disk, and the plastic magnet.

[0032] 1 is a schematic diagram showing the appearance of an air conditioning apparatus 100 according to an embodiment of the present disclosure. FIG. 2 is a schematic diagram showing the configuration of the air conditioning apparatus 100. FIG. 3 is a cross-sectional view of an indoor fan 24 and an indoor fan motor 241. FIG. 4 is a cross-sectional view of a rotor 52. FIG. 5 is a perspective view of a rotor 52. FIG. 6 is a perspective view of a disk 62 constituting the rotor 52. FIG. 7 is a perspective view of a plastic magnet 63 constituting the rotor 52. FIG. 8 is a schematic diagram showing a first step of a method for manufacturing the rotor 52. FIG. 9 is a schematic diagram showing a second step of a method for manufacturing the rotor 52. FIG. 10 is a schematic diagram showing a third step of a method for manufacturing the rotor 52. FIG. 11 is a schematic diagram showing a fourth step of a method for manufacturing the rotor 52. FIG. 12 is a schematic diagram showing a fifth step of a method for manufacturing the rotor 52. FIG. 13 is a schematic diagram showing a sixth step of a method for manufacturing the rotor 52.

[0033] 1 shows the appearance of an air conditioning apparatus 100 according to an embodiment of the present disclosure. The air conditioning apparatus 100 has an outdoor unit 10 that functions as a heat source, an indoor unit 20 that provides conditioned air to a user, and a connecting pipe 30 that connects the outdoor unit 10 and the indoor unit 20.

[0034] (2) Detailed Configuration Fig. 2 shows the configuration of the air conditioning apparatus 100. The air conditioning apparatus 100 has a refrigerant circuit 90 through which refrigerant R circulates.

[0035] (2-1) Outdoor Unit 10 The outdoor unit 10 is a device for obtaining hot heat or cold heat from outdoor air, which is a heat source. The outdoor unit 10 has, as components related to the refrigerant circuit 90, a compressor 11, a four-way switching valve 12, an outdoor heat exchanger 13, an outdoor fan 14, an outdoor expansion valve 15, an accumulator 16, a liquid shut-off valve 17, and a gas shut-off valve 18. The outdoor unit 10 also has, as a component related to the electrical system, an outdoor unit control unit 19.

[0036] The compressor 11 includes a compressor motor 111, a suction pipe 11a, and a discharge pipe 11b. The compressor 11 compresses the low-pressure gaseous refrigerant R drawn in through the suction pipe 11a by the power of the compressor motor 111, and discharges the high-pressure gaseous refrigerant R from the discharge pipe 11b.

[0037] The four-way selector valve 12 switches the connection of the refrigerant circuit 90 depending on whether the refrigerant circuit 90 is in cooling operation or heating operation. During cooling operation, the four-way selector valve 12 forms the connection shown by the solid line in Fig. 2. During heating operation, the four-way selector valve 12 forms the connection shown by the dashed line in Fig. 2.

[0038] The outdoor heat exchanger 13 takes in cold or hot heat from the outdoor air into the refrigerant R. The outdoor heat exchanger 13 functions as a condenser or a heat radiator during cooling operation, and as an evaporator or a heat absorber during heating operation.

[0039] The outdoor fan 14 moves the outdoor air so that the outdoor air passes through the outdoor heat exchanger 13, thereby promoting heat exchange between the outdoor air and the refrigerant R. The outdoor fan 14 is driven by the power of an outdoor fan motor 141.

[0040] The outdoor expansion valve 15 is a device for reducing the pressure of the refrigerant R. The outdoor expansion valve 15 is a valve whose opening degree is adjusted by, for example, electrical control.

[0041] The accumulator 16 separates and stores the liquid refrigerant component from the circulating refrigerant R, and allows the gas refrigerant component to pass through.

[0042] The liquid shutoff valve 17 and the gas shutoff valve 18 are valves that are manually opened and closed by an installer of the outdoor unit 10. The liquid shutoff valve 17 opens and closes the flow path of the refrigerant R in a liquid state or a two-phase gas-liquid state. The gas shutoff valve 18 opens and closes the flow path of the refrigerant R in a gas state.

[0043] The outdoor unit control unit 19 acquires signals from various sensors (not shown) and further controls the compressor motor 111, the outdoor fan motor 141, the outdoor expansion valve 15, and the like.

[0044] (2-2) Indoor Unit 20 The indoor unit 20 is a device for providing hot or cold heat to a user in the form of conditioned air. The indoor unit 20 has an indoor heat exchanger 23 and an indoor fan 24 as components related to the refrigerant circuit 90. Furthermore, the indoor unit 20 has an indoor unit control unit 29 as a component related to the electrical system.

[0045] The indoor heat exchanger 23 transfers the cold or hot heat of the refrigerant R to the indoor air. The indoor heat exchanger 23 functions as an evaporator or a heat absorber during cooling operation. The outdoor heat exchanger 13 functions as a condenser or a radiator during heating operation.

[0046] The indoor fan 24 moves the indoor air so that the indoor air passes through the indoor heat exchanger 23, thereby promoting heat exchange between the indoor air and the refrigerant R. The indoor fan 24 is driven by the power of an indoor fan motor 241.

[0047] The indoor unit control unit 29 acquires signals from various sensors (not shown). Furthermore, the indoor unit control unit 29 controls the indoor fan motor 241 and the like. In addition, the indoor unit control unit 29 transmits and receives data, commands, status, and other signals to and from the outdoor unit control unit 19 via communication.

[0048] (2-3) Communication Pipe 30 Inside the communication pipe 30, a liquid refrigerant pipe 31, a gas refrigerant pipe 32, and an electrical communication line 35 are arranged. The liquid refrigerant pipe 31 allows refrigerant R in a liquid state or a two-phase gas-liquid state to move between the outdoor unit 10 and the indoor unit 20. The liquid refrigerant pipe 31 allows refrigerant R in a gas state to move between the outdoor unit 10 and the indoor unit 20. The electrical communication line 35 allows signal transmission between the outdoor unit control unit 19 and the indoor unit control unit 29, thereby constituting the air conditioning apparatus control unit 9.

[0049] (3) Detailed Configuration of the Indoor Fan 24 and the Indoor Fan Motor 241 FIG. 3 shows the indoor fan 24 and the indoor fan motor 241.

[0050] (3-1) Indoor Fan 24 The indoor fan 24 is a cross-flow fan. The indoor fan 24 is fixed to the rotor 52 of the indoor fan motor 241.

[0051] (3-2) Indoor Fan Motor 241 The indoor fan motor 241 includes a stator 51, a rotor 52, and a bearing 53.

[0052] (3-2-1) Stator 51 The stator 51 has an iron core 71 and a coil 72. When a current flows through the coil 72, the coil 72 generates a magnetic field.

[0053] 4 rotates by interacting with the magnetic field generated by the coil 72 of the stator 51. The rotor 52 is an outer rotor and has a larger outer diameter than the stator 51, and furthermore, has a larger inner diameter than the outer diameter of the stator 51. The rotor 52 has a shaft 61, a disk 62, a plastic magnet 63, and a resin mold 64.

[0054] (3-2-2-1) Shaft 61 As shown in Fig. 5, the shaft 61 defines an axis 63a of the rotor 52. The rotor 52 rotates around the axis 63a.

[0055] (3-2-2-2) Disk 62 The disk 62 shown in Fig. 5 serves to firmly fix the shaft 61 to the resin mold 64. The disk 62 is made of metal. The entire disk 62 is disposed inside the resin mold 64.

[0056] 6, the disk 62 has a center hole 62a and multiple through holes 62b. The center hole 62a is for fixing the shaft 61 to the disk 62 with the shaft 61 passing through it. The inner diameter of the center hole 62a does not have a clearance with respect to the outer diameter of the shaft 61. The shaft 61 and the disk 62 are fixed by press-fitting the shaft 61 into the center hole 62a.

[0057] The plurality of through holes 62b are for allowing a resin material to pass through when forming the resin mold 64. The plurality of through holes 62b are formed separately from the center hole 62a.

[0058] (3-2-2-3) Plastic Magnet 63 The plastic magnet 63 shown in Fig. 7 interacts with the magnetic field generated by the coil 72 to generate a rotational force for the rotor 52. The plastic magnet 63 has a circular ring shape centered on the axis 63a of the rotor 52. The plastic magnet 63 has a first end face 63b and a second end face 63c that are spaced apart in the direction in which the axis 63a extends. At least one of the first end face 63b and the second end face 63c may have a protrusion 63x and a recess 63y.

[0059] The plastic magnet 63 is made of a resin material containing a magnetic substance. The linear expansion coefficient of the plastic magnet 63 is 3.5×10 －５ ( / ℃).

[0060] The magnetic material is, for example, rare earth magnet powder, ferrite magnet powder, etc. The resin material is, for example, a thermosetting resin or a thermoplastic resin.

[0061] Examples of thermosetting resins include epoxy resins, bismaleimide resins, phenolic resins, urea resins, melamine resins, alkyd resins, unsaturated polyester resins, DAP resins, and polyurethane resins.

[0062] Examples of thermoplastic resins include vinyl polymers (polyethylene, polypropylene, polyvinyl chloride, polystyrene, ABS resin, AS resin, polymethacrylic acid, polymethacrylic acid ester, polyacrylic acid, polyacrylic acid ester, polyvinylidene chloride, etc.), polyamides (Nylon 6 (registered trademark), Nylon 66 (registered trademark), aromatic polyamide, etc.), polyesters (polyethylene terephthalate, polybutylene terephthalate, etc.), fluororesins (PTFE, FEP, PFA, etc.), polyacetal, polycarbonate, modified polyphenylene ether, polysulfone, polyethersulfone, polyphenylene sulfide, polyarylate, polyetherimide, polyetheretherketone, polyetherketone, liquid crystalline polyester, and copolymers (random, block, graft, or alternating copolymers, etc.) in which the skeletons of these resins are arbitrarily combined.

[0063] (3-2-2-4) Resin mold 64 The resin mold 64 fixes at least the disk 62 and the plastic magnet 63 to each other. The resin mold 64 is made of a thermosetting resin or a thermoplastic resin. The linear expansion coefficient of the resin mold 64 is 3.5×10 －５ ( / ° C.) The resin mold 64 is in contact with the first end surface 63 b of the plastic magnet 63 .

[0064] (3-2-3) Bearing 53 The bearing 53 shown in Fig. 3 is for rotatably supporting the shaft 61. The bearing 53 is installed in the stator 51. The bearing 53 is, for example, a sliding bearing or a rolling bearing.

[0065] (4) Manufacturing Method of Rotor 52 The rotor 52 is manufactured by, for example, the manufacturing method described below.

[0066] 8, a first mold 81 is prepared. The first mold 81 is used to form the resin mold 64. The first mold 81 has a first recess 81a and a second recess 81b. The first recess 81a functions as a jig for supporting the shaft 61. The second recess 81b functions as a jig for supporting the plastic magnet 63.

[0067] In the second step shown in FIG. 9, the shaft 61 is press-fitted into the central hole 62a of the disk 62, thereby fixing the shaft 61 and the disk 62 to each other.

[0068] 10, the shaft 61 fixed to the disk 62 is placed in the first recess 81a, and the plastic magnet 63 is placed in the second recess 81b.

[0069] 11 , the second mold 82 is fitted into the first mold 81. The second mold 82 has a third recess 82a. The third recess 82a functions as a jig for supporting the shaft 61. An internal space 83 is formed between the first mold 81 and the second mold 82 that are fitted together.

[0070] 12, the resin material 69 is injected or poured into the internal space 83. The resin material 69 is solidified.

[0071] 13 , the first mold 81 and the second mold 82 are removed. The solidified resin material 69 forms a resin mold 64. The resin mold 64 fixes the shaft 61, the disk 62, and the plastic magnet 63 together. This completes the rotor 52.

[0072] Thereafter, the indoor fan 24 is fixed to the rotor 52, and then the rotor 52 is combined with the stator 51 and the bearing 53, thereby completing the indoor fan motor 241.

[0073] (5) Features (5-1) The rotor 52 has a metal disk 62. Therefore, the metal parts group consisting of the shaft 61 and the disk 62 are in close contact with the resin mold 64 over a wide area, so that the resin mold 64 can firmly fix the shaft 61.

[0074] Without the disk 62, in order to firmly secure the shaft 61 to the resin mold 64, it would be necessary to ensure a large length in the direction of the axis 63a at the point where the shaft 61 and the resin mold 64 come into contact, which would inevitably result in an increase in the size of the rotor 52. In contrast, the rotor 52 of the present disclosure has the disk 62, which can strengthen the security of the shaft 61 to the resin mold 64, and therefore the size of the rotor 52 in the direction of the axis 63a can be reduced.

[0075] (5-2) The shaft 61 and the disk 62 are firmly fixed to each other by press-fitting, and therefore the resin mold 64 and the shaft 61 are also firmly fixed to each other.

[0076] (5-3) The entire disk 62 is placed in the resin mold 64. This brings the entire surface area of ​​the disk 62 into contact with the resin mold 64. Therefore, the resin mold 64 firmly fixes the disk 62.

[0077] (5-4) The disk 62 has a plurality of through holes 62b in addition to the central hole 62a. The resin mold 64 fits into the plurality of through holes 62b. This makes it possible to more firmly fix the resin mold 64 to the disk 62.

[0078] (5-5) The resin mold 64 is fixed to the first end surface 63b of the plastic magnet 63. Therefore, the resin mold 64 fixes the shaft 61, the disk 62, and the plastic magnet 63 together.

[0079] If the resin mold 64 does not exist and instead the plastic magnet 63 extends from the outer edge of the rotor to reach the shaft 61, the －５ Since a force is applied to the plastic magnet 63, which has a linear expansion coefficient of more than 3.5×10 ( / °C), the plastic magnet 63 is easily broken. －５ This is achieved by using a resin mold 64 having a linear expansion coefficient of less than 1 / °C. Therefore, the risk of damage to the rotor 52 can be reduced.

[0080] (5-6) The rotor 52 is an outer rotor. Therefore, the distance from the metal parts consisting of the shaft 61 and the disk 62 to the plastic magnet 63 is long. The transmission of force over this long distance is carried out by the resin mold 64, which is more durable than the plastic magnet 63.

[0081] (5-7) The plastic magnet 63 is made of a resin material containing a magnetic substance, so it is easy to mold the plastic magnet 63.

[0082] (5-8) The resin mold 64 is made of a thermosetting resin or a thermoplastic resin, which makes it easy to process.

[0083] (5-9) The linear expansion coefficient of the resin mold 64 is smaller than that of the plastic magnet 63. Therefore, the volume of the resin mold 64 is less likely to change due to temperature changes, and damage such as cracking is less likely to occur.

[0084] (5-10) When forming the resin mold 64 in the manufacture of the rotor 52, the first mold 81 and the second mold 82 hold both the shaft 61 and the plastic magnet 63. Therefore, the resin mold 64 can be manufactured so that it is precisely perpendicular to the axis 63a of the shaft 61 and the plastic magnet 63. This reduces vibrations and damage to the rotor 52 that occur when the rotor 52 rotates.

[0085] <Modifications of the embodiment> (6) Modifications (6-1) First modification In the above-described embodiment, the first mold 81 and the second mold 82 not only function as molds for forming the resin mold 64, but also function as jigs for supporting the shaft 61 and the plastic magnet 63. Alternatively, the jigs for supporting the shaft 61 and the plastic magnet 63 may be prepared as objects separate from the first mold 81 and the second mold 82. In that case, the jig needs to be fixed to either the first mold 81 or the second mold 82.

[0086] (6-2) Second Modification In the above embodiment, the resin mold 64 is in contact with the first end face 63b but not with the second end face 63c of the plastic magnet 63. Alternatively, the resin mold 64 may have a shape that contacts both the first end face 63b and the second end face 63c.

[0087] (6-3) Third Modification In the above-described embodiment, the rotor 52 is an outer rotor. Alternatively, the rotor 52 may be an inner rotor. In this case, the outer diameter of the rotor 52 is smaller than the outer diameter of the stator 51.

[0088] <Conclusion> Although the embodiments of the present disclosure have been described above, it will be understood that various changes in form and details can be made without departing from the spirit and scope of the present disclosure as defined in the claims.

[0089] 24: Indoor fan (cross flow fan) 51: Stator 52: Rotor 53: Bearing 61: Shaft 62: Circular plate 62a: Center hole 62b: Through hole 63: Plastic magnet 63a: Axis center 63b: First end face (end face) 63c: Second end face (end face) 63x: Convex portion 63y: Concave portion 64: Resin mold 69: Resin material 81: First mold (mold) 82: Second mold (mold) 83: Internal space 100: Air conditioner 241: Indoor fan motor (motor)

[0090] Japanese Patent Application Laid-Open No. 2005-069580

Claims

1. A motor (241) comprising: a rotor (52) having a shaft (61), a disk (62) having a central hole (62a) through which the shaft passes, an annular plastic magnet (63), and a resin mold (64) that fixes the shaft, the disk, and the plastic magnet.

2. The motor according to claim 1, wherein the shaft is fixed to the disk by press-fitting into the central hole.

3. The motor according to claim 1 or claim 2, wherein the entire disk is disposed within the resin mold.

4. The motor according to any one of claims 1 to 3, wherein the disc has a plurality of through holes (62b) in addition to the central hole.

5. A motor according to any one of claims 1 to 4, wherein the plastic magnet has an axis (63a) and two end faces (63b, 63c) spaced apart in the direction in which the axis extends, and the resin mold is in contact with at least one of the two end faces.

6. The motor according to any one of claims 1 to 5, further comprising a stator (51) that magnetically interacts with the rotor, the rotor being an outer rotor having an outer diameter larger than that of the stator.

7. The motor according to any one of claims 1 to 6, wherein the plastic magnet is made of a resin material containing a magnetic substance.

8. The motor according to any one of claims 1 to 7, wherein the resin mold is made of a thermosetting resin or a thermoplastic resin.

9. The linear expansion coefficient of the plastic magnet is 3.5 x 10 －５ ( / °C), and the linear expansion coefficient of the resin mold is greater than 3.5 × 10 －５ The motor according to any one of claims 1 to 8, wherein the temperature is less than 100°C / °F.

10. An air conditioning device (100) comprising: a motor according to any one of claims 1 to 9; and a cross-flow fan (24) fixed to the rotor of the motor.

11. A method for manufacturing a motor (241), comprising the steps of: preparing a shaft (61), a disk (62) having a central hole (62a), an annular plastic magnet (63), and a resin material (69); fixing the shaft and the disk by pressing the shaft into the central hole; holding both the shaft and the plastic magnet in a mold (81, 82) or a jig fixed to the mold; injecting or pouring the resin material into the internal space of the mold; and hardening the resin material to form a resin mold (64) that fixes the shaft, the disk, and the plastic magnet.

12. The manufacturing method according to claim 11, wherein after the resin mold is formed, the entire disk is placed within the resin mold.

13. A manufacturing method as described in claim 11 or claim 12, wherein the plastic magnet has an axis (63a) and two end faces (63b, 63c) spaced apart in the direction in which the axis extends, and after the resin mold is formed, the resin mold is in contact with at least one of the two end faces.

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