Method for manufacturing a ring magnet, ring magnet, rotor, motor, blower, and refrigeration device.

Abstract

The present invention provides a method for manufacturing a ring magnet that facilitates the alignment of the magnetization easy axis of the magnetic powder in bonded magnet material, as well as a ring magnet, rotor, motor, blower, and refrigeration apparatus. [Solution] The method for manufacturing a ring magnet includes an injection step of injecting a bonded magnet material 50a containing magnetic powder into a cavity 71, and a modification step of increasing the axial length CL of the cavity 71 in the cylindrical axis direction A1. The injection step is performed when the axial length CL of the cavity 71 is smaller than the length of the ring magnet in the cylindrical axis direction A1.

Description

Technical Field

[0001] The present disclosure relates to a method for manufacturing a ring magnet, a ring magnet, a rotor, a motor, a blower, and a refrigeration device.

Background Art

[0002] Bond magnets are manufactured by injecting a bond magnet material into a cavity of a mold. Patent Document 1 discloses that by shortening the flow path length of the bond magnet material, the low-viscosity state of the bond magnet material can be maintained for a relatively long time, so that the orientation of magnetic powder can be controlled well.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, the bond magnet material flows when being injected into the cavity. In some cases, the easy magnetization axes of the magnetic powder are difficult to be aligned due to this flow.

Means for Solving the Problems

[0005] A method for manufacturing a ring magnet according to a first aspect for solving this problem is a method for manufacturing a ring magnet, including a mold body having a cylindrical cavity, and in a mold configured to be able to change an axial length in a cylindrical axis direction of the cavity, an injection step of injecting a bond magnet material containing magnetic powder into the cavity, and a change step of increasing the axial length, wherein the magnetic powder has a longer length in a second direction orthogonal to an easy magnetization axis than a length in a first direction along the easy magnetization axis, and the injection step is performed when the axial length is smaller than a length of the ring magnet in the cylindrical axis direction.

[0006] In this configuration, the bonded magnet material is injected into the cavity when the axial length of the cavity is smaller than the length of the ring magnet in the axial direction of the cylinder that will be ultimately manufactured. The smaller the axial length of the cavity, the more the flow of the bonded magnet material in the axial direction is suppressed, so that the easy magnetization axis of the magnetic particles of the bonded magnet material is more likely to align with the circumferential and radial directions of the cavity. Therefore, the magnetic force of the ring magnet can be increased.

[0007] The method for manufacturing a ring magnet according to the second aspect is the method for manufacturing a ring magnet according to the first aspect, wherein the modification step includes a first modification step of setting the axial length to a first length and a second modification step of increasing the axial length by a second length, and the injection step includes a first injection step of injecting the bonded magnet material into the cavity and a second injection step of injecting the bonded magnet material into the cavity, wherein the first injection step is performed after the first modification step, the second modification step is performed after the first injection step, and the second injection step is performed after the second modification step.

[0008] In this configuration, a bonded magnet with a length of a first length in the axial direction of the cylinder is formed in the first injection step, and a bonded magnet with a length of a second length in the axial direction of the cylinder is formed in the second injection step. Since the first and second lengths are smaller than the length in the axial direction of the ring magnet that is finally manufactured, the easy magnetization axis of the magnetic powder of the bonded magnet material injected in each injection step can be easily aligned in the circumferential and radial directions.

[0009] The third aspect of the method for manufacturing a ring magnet is the method for manufacturing a ring magnet according to the second aspect, wherein the first length or the second length is smaller than the width of the cavity in the radial direction of the cavity.

[0010] With this configuration, the length of the bonded magnet formed in each injection step in the axial direction of the cylinder can be made smaller than the width of the ring magnet in the radial direction.

[0011] The method for manufacturing a ring magnet according to the fourth aspect is the method for manufacturing a ring magnet according to the second or third aspect, wherein the modification step includes a third modification step of increasing the axial length by a third length, and the injection step includes a third injection step of injecting the bonded magnet material into the cavity, the third modification step is performed after the second injection step, and the third injection step is performed after the third modification step.

[0012] This configuration allows for the manufacture of a ring magnet composed of three bonded magnets.

[0013] The fifth aspect of the method for manufacturing a ring magnet is the method for manufacturing a ring magnet according to any one of the second to fourth aspects, wherein the mold is arranged on the inner or outer circumferential side of the cavity in the radial direction of the cavity and includes a magnetic field generating unit that generates a magnetic field within the cavity, and the second modification step is performed based on the temperature of the bonded magnet material injected in the first injection step being below a reference temperature, the reference temperature being set based on the temperature at which the bonded magnet material hardens.

[0014] In this configuration, the bonded magnet material injected in the first injection step hardens before the axial length of the cavity is increased by the second length in the second modification step. Therefore, when the bonded magnet material is injected in the second injection step, the bonded magnet material injected in the first injection step does not need to be oriented. In this way, the magnetic field generating unit only needs to orient the unhardened bonded magnet material in the cavity, so the size of the magnetic field generating unit in the cylindrical axis direction can be reduced.

[0015] The method for manufacturing a ring magnet according to the sixth aspect is to perform the injection step and the modification step simultaneously in the method for manufacturing a ring magnet according to the first aspect.

[0016] In this configuration, the bonded magnet material is injected into the cavity, and the axial length of the cavity increases. The axial length of the cavity when the bonded magnet material is injected into it is smaller than the length of the ring magnet in the axial direction of the cylinder that is ultimately manufactured. Therefore, the easy magnetization axis of the magnetic powder of the bonded magnet material formed in each injection step can be easily aligned in the circumferential and radial directions.

[0017] The method for manufacturing a ring magnet according to the seventh aspect is the method for manufacturing a ring magnet according to any one of the methods from the first to the sixth aspect, wherein in the injection step, the bonded magnet material is injected in a direction along the cylindrical axis.

[0018] With this configuration, the easy magnetization axis of the magnetic powder of the bonded magnet material injected in the axial direction of the cylinder is more likely to be aligned in the circumferential and radial directions.

[0019] The eighth ring magnet that solves this problem is a cylindrical ring magnet having a cylindrical first ring magnet portion and a cylindrical second ring magnet portion, wherein the first ring magnet portion and the second ring magnet portion are bonded magnets, and the second ring magnet portion overlaps the first ring magnet portion in the cylindrical axis direction of the ring magnet.

[0020] In this configuration, a ring magnet is formed by the overlapping of two bonded magnets. Therefore, the magnetic force of the ring magnet can be increased compared to when a ring magnet is formed by a single bonded magnet.

[0021] The ring magnet of the ninth aspect is a ring magnet of the eighth aspect having a cylindrical third ring magnet portion, the third ring magnet portion being a bonded magnet, and the third ring magnet portion overlapping the second ring magnet portion in the direction of the cylindrical axis.

[0022] According to this configuration, a ring magnet can be formed using three or more bonded magnets.

[0023] In the ring magnet of the tenth aspect, in the ring magnet of the eighth or ninth aspect, the second ring magnet portion is integral with the first ring magnet portion.

[0024] According to this configuration, since the first ring magnet portion and the second ring magnet portion are integral, the handling property of the ring magnet is improved.

[0025] The rotor of the eleventh aspect that solves this problem includes any one ring magnet from the eighth aspect to the tenth aspect.

[0026] According to this configuration, a rotor using a ring magnet with high magnetic force can be configured.

[0027] The motor of the twelfth aspect that solves this problem includes the rotor of the eleventh aspect and a stator.

[0028] According to this configuration, since the magnetic force of the ring magnet of the rotor is improved, the rotational characteristics of the motor such as rotational torque and rotational accuracy can be improved.

[0029] The blower of the thirteenth aspect that solves this problem includes the motor of the twelfth aspect and a blower device driven by the motor.

[0030] According to this configuration, since the blower device is driven by a motor with improved rotational characteristics, an appropriate rotational force can be obtained for the fluid machine.

[0031] The refrigerator of the fourteenth aspect that solves this problem includes the motor of the twelfth aspect.

[0032] According to this configuration, the refrigerator can be stably driven by a motor with improved rotational characteristics.

Brief Description of Drawings

[0033] [Figure 1] It is a schematic diagram of the blower according to the first embodiment. [Figure 2]This is a cross-sectional view of the motor in Figure 1, showing the ring magnet along the cylindrical axis direction. [Figure 3] Figure 2 is a plan view of the ring magnet as seen from the direction of the cylindrical axis. [Figure 4] Figure 2 is a perspective view of the ring magnet. [Figure 5] Figure 2 is a schematic diagram of the mold used to manufacture the ring magnet. [Figure 6] This is a cross-sectional view of the mold shown in Figure 5, along the line D6-D6. [Figure 7] Figure 2 is a first schematic diagram showing the manufacturing method of the ring magnet. [Figure 8] This is a second schematic diagram showing the manufacturing method of the ring magnet shown in Figure 2. [Figure 9] This is a third schematic diagram showing the manufacturing method of the ring magnet shown in Figure 2. [Figure 10] This is a schematic diagram of a mold used for manufacturing a ring magnet according to the second embodiment. [Figure 11] This is a schematic diagram of a mold used in the manufacture of a ring magnet according to the first modified example. [Figure 12] This is a schematic diagram of a mold used in the manufacture of a ring magnet according to the second modified example. [Modes for carrying out the invention]

[0034] <Embodiment> Referring to Figures 1 to 9, a blower 1, motor 20, rotor 40, ring magnet 50, and a method for manufacturing the ring magnet 50 according to an embodiment will be described.

[0035] <Blower> The blower 1 shown in Figures 1 and 2 is installed, for example, in the indoor unit of an air conditioner. The air conditioner performs air conditioning operations such as cooling, heating, and dehumidifying the room. The blower 1 performs functions such as drawing in and blowing out air.

[0036] The blower 1 comprises a blower device 10 and a motor 20. The blower device 10 is driven by the motor 20. The blower device 10 has, for example, a cylindrical cross-flow fan 11. Air is drawn in and blown out by the rotation of the cross-flow fan 11.

[0037] <motor> Motor 20 is, for example, an outer rotor type motor. Motor 20 comprises a stator 30 and a rotor 40.

[0038] The stator 30 includes a coil 31, a coil holder 32, a cylindrical first cylindrical portion 33, a disc portion 34, and a stator core 35. The coil 31 is formed by winding the same wire around the teeth of the stator core 35. The stator core 35 is made of a material including a soft magnetic material. The stator core 35 is constructed, for example, by laminating electromagnetic steel sheets in the cylindrical axis direction A1. The coil holder 32, the first cylindrical portion 33, and the disc portion 34 are made of, for example, resin. The coil holder 32, the first cylindrical portion 33, and the disc portion 34 are molded integrally. The coil holder 32 holds the coil 31 by resin molding. The first cylindrical portion 33 is located on the outer circumferential side of the coil holder 32. The disc portion 34 connects the coil holder 32 and the first cylindrical portion 33. The stator 30 is provided with a cylindrical arrangement space. The cylindrical arrangement space is the space located between the coil holding portion 32 and the first cylindrical portion 33 of the stator 30. Note that the coil holding portion 32, the first cylindrical portion 33, and the disc portion 34 may be molded individually.

[0039] <Rotor> The rotor 40 is equipped with a ring magnet 50. The ring magnet 50 is cylindrical. One end of the ring magnet 50 in the direction of the cylindrical axis A1 is located in a cylindrical arrangement space. The other end of the ring magnet 50 in the direction of the cylindrical axis A1 is attached to the magnet holder 41, which will be described later.

[0040] The rotor 40 includes, in addition to the ring magnet 50, a magnet holder 41, a second cylindrical portion 42, and a rotating shaft 43. In the cylindrical axis direction A1 of the ring magnet 50, the magnet holder 41 has a first surface on the blower 10 side and a second surface on the opposite side of the first surface. The magnet holder 41 holds the ring magnet 50 on the second surface. The magnet holder 41 is made of, for example, a resin material. The second cylindrical portion 42 is located on the outer circumference side of the ring magnet 50. The rotating shaft 43 is fixed to the magnet holder 41. The rotating shaft 43 is located inside the ring magnet 50. The rotating shaft 43 is located on the inner circumference side of the coil holder 32 of the stator 30. A bearing 21 is positioned between the rotating shaft 43 and the coil holder 32. The rotor 40 is supported by the stator 30 via the bearing 21. The cross-flow fan 11 of the blower 10 is fixed to the first surface of the magnet holder 41.

[0041] When current flows through the coil 31 of the stator 30, a magnetic field is generated. This magnetic field causes the rotor 40, which is equipped with a ring magnet 50, to rotate. This, in turn, causes the cross-flow fan 11 of the blower 10, which is fixed to the magnet holder 41 of the rotor 40, to rotate.

[0042] <Ring Magnet> As shown in Figure 3, the ring magnet 50 is an anisotropic magnet having two or more magnetic poles arranged in the circumferential direction A2 of the ring magnet 50 on either its inner or outer surface. In one example, the ring magnet 50 has two or more magnetic poles arranged in the circumferential direction A2 on its inner surface, and no magnetic poles on its outer surface. In another example, the ring magnet 50 has two or more magnetic poles arranged in the circumferential direction A2 on its outer surface, and no magnetic poles on its inner surface. In this embodiment, the two or more magnetic poles are arranged on the inner surface of the ring magnet 50. Note that Figure 3 is a plan view of the ring magnet 50 as seen from the side of the fourth ring magnet section 54, which will be described later, in the cylindrical axis direction A1.

[0043] As shown in Figure 4, the ring magnet 50 is constructed by stacking multiple bond magnets in the cylindrical axis direction A1. The bond magnets contain magnetic anisotropy. Examples of materials for the magnetic powder include fine powdered or granular ferrite-based magnets or rare-earth-based magnets. The bond magnets contain a binder such as nylon resin or PPS (polyphenylene sulfide) resin. The bond magnet is formed when the bond magnet material 50a (see Figure 7), which is a mixture of magnetic anisotropy and molten binder, hardens.

[0044] The ring magnet 50 has a cylindrical first ring magnet section 51 and a cylindrical second ring magnet section 52. The first ring magnet section 51 and the second ring magnet section 52 are bonded magnets. The material of the bonded magnet in the second ring magnet section 52 is the same type as the bonded magnet in the first ring magnet section 51. The second ring magnet section 52 overlaps with the first ring magnet section 51 in the cylindrical axis direction A1 of the ring magnet 50.

[0045] The second ring magnet portion 52 is integral with the first ring magnet portion 51. The second ring magnet portion 52 is molded integrally with the first ring magnet portion 51. No interface is formed between the first ring magnet portion 51 and the second ring magnet portion 52. One end of the first ring magnet portion 51 in the cylindrical axis direction A1 is fused to one end of the second ring magnet portion 52 in the cylindrical axis direction A1.

[0046] The ring magnet 50 further has a cylindrical third ring magnet section 53. The third ring magnet section 53 is a bonded magnet. The material of the bonded magnet in the third ring magnet section 53 is the same type as the bonded magnet in the second ring magnet section 52. The third ring magnet section 53 overlaps with the second ring magnet section 52 in the cylindrical axis direction A1.

[0047] The third ring magnet portion 53 is integral with the second ring magnet portion 52. The third ring magnet portion 53 is molded integrally with the second ring magnet portion 52. No interface is formed between the second ring magnet portion 52 and the third ring magnet portion 53. The other end of the second ring magnet portion 52 in the cylindrical axis direction A1 is fused to one end of the third ring magnet portion 53 in the cylindrical axis direction A1.

[0048] The ring magnet 50 further has a cylindrical fourth ring magnet section 54. The fourth ring magnet section 54 is a bonded magnet. The bonded magnet of the fourth ring magnet section 54 is made of the same material as the bonded magnet of the third ring magnet section 53. The fourth ring magnet section 54 overlaps with the third ring magnet section 53 in the cylindrical axis direction A1.

[0049] The fourth ring magnet portion 54 is integral with the third ring magnet portion 53. The fourth ring magnet portion 54 is molded integrally with the third ring magnet portion 53. No interface is formed between the third ring magnet portion 53 and the fourth ring magnet portion 54. The other end of the third ring magnet portion 53 in the cylindrical axis direction A1 is fused to one end of the fourth ring magnet portion 54 in the cylindrical axis direction A1.

[0050] As shown in Figures 1 and 3, the first magnet length ML1 of the first ring magnet section 51 in the cylindrical axis direction A1 is smaller than the magnet width MW of the ring magnet 50 in the radial direction A3. The magnet width MW of the ring magnet 50 is, for example, 3 mm or more and 7 mm or less. The second magnet length ML2 of the second ring magnet section 52 in the cylindrical axis direction A1 is smaller than the magnet width MW of the ring magnet 50 in the radial direction A3. The third magnet length ML3 of the third ring magnet section 53 in the cylindrical axis direction A1 is smaller than the magnet width MW of the ring magnet 50 in the radial direction A3. The fourth magnet length ML4 of the fourth ring magnet section 54 in the cylindrical axis direction A1 is smaller than the magnet width MW of the ring magnet 50 in the radial direction A3. In this embodiment, the sum of the first magnet length ML1, the second magnet length ML2, the third magnet length ML3, and the fourth magnet length ML4 is equal to the magnet length ML of the ring magnet 50 in the cylindrical axis direction A1.

[0051] Near the outer surface of the ring magnet 50 shown in Figure 3, a portion of the magnetic powder of the bonded magnet is oriented in the circumferential direction A2 or the radial direction A3. The area near the outer surface of the ring magnet 50 is, for example, a region closer to the outer surface than a first intermediate line located midway between the inner and outer surfaces in the radial direction A3 when viewed from the cylindrical axis direction A1. Preferably, the area near the outer surface of the ring magnet 50 is a region closer to the outer surface than a second intermediate line located midway between the first intermediate line and the outer surface in the radial direction A3 when viewed from the cylindrical axis direction A1. Near the outer surface of the ring magnet 50, the sum of the orientation rate of the bonded magnet in the circumferential direction A2 and the orientation rate of the bonded magnet in the radial direction A3 is greater than the orientation rate of the bonded magnet in the cylindrical axis direction A1.

[0052] In this embodiment, orientation means that the easy magnetization axis of the magnetic powder contained in the bonded magnet material 50a is aligned in a predetermined direction. The orientation ratio is defined by the following equation (1) as the average value of the orientation component of each magnetic powder with respect to the predetermined direction.

[0053]

number

[0054] X is the orientation factor. N is the total number of magnetic particles contained in any given region. θ is the angle between a given direction and the easy magnetization axis of each magnetic particle. Any given region is defined, for example, by the observation range of a scanning electron microscope (SEM).

[0055] <How to manufacture a ring magnet> The manufacturing method for the ring magnet 50 will be described with reference to Figures 5 to 9. The manufacturing method for the ring magnet 50 includes an injection step and a modification step. A molding die 60 is used in the manufacturing method for the ring magnet 50.

[0056] [Mold] As shown in Figure 5, the mold 60 comprises a mold body 70, a magnetic field generating unit 80, and a movable part 90. The mold body 70 has a cylindrical cavity 71. The mold body 70 is made of a non-magnetic material. An example of a non-magnetic material is non-magnetic stainless steel. The non-magnetic materials described later are also made of the same material. Note that Figure 5 is a cross-sectional view of the mold 60 in Figure 6 along the line D5-D5.

[0057] The mold 60 is configured to allow the axial length CL of the cavity 71 in the cylindrical axis direction A1 to be changed. The axial length CL of the cavity 71 is the length from the bottom surface 71a of the cavity 71 to the opening 71b of the cavity 71. The opening 71b of the cavity 71 is, for example, the part in the cylindrical axis direction A1 that is at the same position as the surface to which the movable part 90 of the mold body 70 is attached.

[0058] The mold body 70 includes, for example, a cylindrical bottom portion 72 and an adjustment portion 73. The bottom portion 72 is positioned in a recess of the mold body 70 formed in the direction of the cylindrical axis A1. The positioning of the bottom portion 72 in the recess of the mold body 70 constitutes the bottom surface 71a of the cavity 71. The surface of the bottom portion 72 facing the opening 71b side of the cavity 71 in the direction of the cylindrical axis A1 is the bottom surface 71a of the cavity 71. The side surfaces of the recess of the mold body 70 are the inner and outer circumferential surfaces of the cavity 71.

[0059] The adjustment unit 73 adjusts the position of the bottom portion 72 relative to the recess of the mold body 70. The adjustment unit 73 is configured to change the position of the bottom portion 72 in the cylindrical axis direction A1 within the recess of the mold body 70, for example. The adjustment unit 73 has, for example, a motor that moves the bottom portion 72 in the cylindrical axis direction A1.

[0060] As shown in Figure 6, the magnetic field generating unit 80 generates a magnetic field within the cavity 71. The magnetic field generating unit 80 is positioned on either the inner or outer circumferential surface side of the cavity 71 in the radial direction A3. In this embodiment, the magnetic field generating unit 80 is positioned on the inner circumferential surface side of the cavity 71 in the radial direction A3. The magnetic field generating unit 80 is positioned inside the mold body 70.

[0061] The magnetic field generating unit 80 has magnetic poles arranged in the circumferential direction A2 of the cavity 71. The magnetic poles of the magnetic field generating unit 80 are located on the inner or outer circumferential surface of the magnetic field generating unit 80. In the manufacture of the ring magnet 50 of this embodiment, the magnetic poles of the magnetic field generating unit 80 are located on the outer circumferential surface of the magnetic field generating unit 80. Multiple magnetic poles are formed at regular intervals on the outer circumferential surface of the magnetic field generating unit 80. Specifically, north poles and south poles are formed alternately at regular intervals on the outer circumferential surface of the magnetic field generating unit 80.

[0062] In the example shown in Figure 6, the magnetic field generating unit 80 has eight poles. In this embodiment, the magnetic field generating unit 80 comprises a plurality of permanent magnets arranged in the circumferential direction A2 of the cavity 71. The magnetic field generating unit 80 may also include electromagnets.

[0063] The magnetic flux from the magnetic field generating unit 80 extends radially in A3 from the magnetic pole of the magnetic field generating unit 80, intersects the inner surface of the cavity 71, and then bends in the circumferential direction A2. Subsequently, the magnetic flux bends radially in A3 again, intersects the inner surface of the cavity 71 once more, and then heads toward the adjacent magnetic pole. In this way, the magnetic flux from the magnetic field generating unit 80 is formed to align along the circumferential direction A2 and the radial direction A3.

[0064] The movable part 90 shown in Figure 5 moves relative to the mold body 70, which is held in a fixed position. The movable part 90 is made of a non-magnetic material. Inside the movable part 90, a spool 91, a runner 92, and a gate 93 are formed. The spool 91 is configured to into which the bonded magnet material 50a is injected. The runner 92 connects the spool 91 and the gate 93. The gate 93 is an opening that connects to the cavity 71. The gate 93 is located near the middle of the cavity 71 in the radial direction A3 when viewed from the cylindrical axis direction A1 (see Figure 6). The gate 93 is located in the same position as the magnetic pole of the magnetic field generating part 80 in the circumferential direction A2.

[0065] A heater may be provided in the movable part 90. The heater suppresses the hardening of the bonded magnet material 50a inside the runner 92 by warming the runner 92.

[0066] [Movement of magnetic particles] Magnetic particles have an easy magnetization axis. The magnetic particles of the bonded magnet material 50a have a length in a second direction perpendicular to the easy magnetization axis that is longer than the length in a first direction along the easy magnetization axis. In other words, the magnetic particles are flattened. When the bonded magnet material 50a is injected into the cavity 71, the magnetic particles of the bonded magnet material 50a are not magnetized.

[0067] When bonded magnet material 50a is injected into cavity 71, the magnetic powder is affected by the magnetic field of the magnetic field generating unit 80. The magnetic powder is subjected to a force by the magnetic field of the magnetic field generating unit 80 such that its easy magnetization axis aligns with the magnetic flux of the magnetic field generating unit 80. Specifically, since the magnetic flux of the magnetic field generating unit 80 is formed radially in A3 near the magnetic poles and circumferentially in A2 between the magnetic poles in the circumferential direction A2, the magnetic powder is subjected to a force by the magnetic field of the magnetic field generating unit 80 such that its easy magnetization axis aligns with the circumferential direction A2 and the radial direction A3. In this way, the magnetic powder moves in a way that changes direction due to the magnetic field of the magnetic field generating unit 80.

[0068] Furthermore, when the bonded magnet material 50a is injected into the cavity 71, the magnetic particles of the bonded magnet material 50a move as follows due to the flow of the bonded magnet material 50a: The magnetic particles of the bonded magnet material 50a that have flowed into the cavity 71 move such that the easy magnetization axis of the magnetic particles is aligned with the direction in which the bonded magnet material 50a flows.

[0069] When the bonded magnet material 50a is injected into the cavity 71, the bonded magnet material 50a flows toward the bottom surface 71a of the cavity 71. This flow of the bonded magnet material 50a causes the easy magnetization axis of the magnetic powder to be oriented in the direction of the cylindrical axis A1. Thus, the flow direction of the bonded magnet material 50a differs from the direction of the magnetic flux of the magnetic field generating unit 80. For this reason, in this embodiment, the flow direction of the bonded magnet material 50a is controlled when injecting the bonded magnet material 50a into the cavity 71. Specifically, the bonded magnet material 50a is made to flow in the circumferential direction A2 and the radial direction A3 by controlling the axial length CL of the cavity 71 through a modification step described later. This makes it easier for the easy magnetization axis of the magnetic powder to align with the direction of the magnetic flux of the magnetic field generating unit 80.

[0070] [Manufacturing method] Next, the method for manufacturing the ring magnet 50 will be described. The method for manufacturing the ring magnet 50 includes an injection step and a modification step, as described above. The method for manufacturing the ring magnet 50 further includes an extraction step and a magnetization step.

[0071] As shown in Figure 7, in the injection process, bonded magnet material 50a containing magnetic powder is injected into the cavity 71. In the injection process, the bonded magnet material 50a is injected in a direction along the cylindrical axis A1. Since the gate 93 of the movable part 90 opens into the opening 71b of the cavity 71, the bonded magnet material 50a is injected in a direction along the cylindrical axis A1.

[0072] In the modification process, the axial length CL of the cavity 71 is increased. In this embodiment, the axial length CL is increased by adjusting the position of the bottom 72 relative to the recess of the mold body 70 using the adjustment unit 73 (see Figure 5). "Increasing the axial length CL of the cavity 71" includes increasing the axial length CL from "0" to a predetermined length, and increasing the axial length CL from a predetermined length.

[0073] In this embodiment, the modification step is performed based on the fact that the temperature of the bonded magnet material 50a injected in the injection step falls below a reference temperature. The reference temperature is set based on the temperature at which the bonded magnet material 50a hardens. The mold 60 is provided with a measuring device for detecting the temperature of the bonded magnet material 50a in the cavity 71. The measuring device detects the temperature of the bonded magnet material 50a in the cavity 71 by a method such as ultrasonic thermometering.

[0074] The reference temperature is set based on the type of binder in the bonded magnet material 50a. For example, the reference temperature is set to a temperature below the temperature at which the magnetic powder in the bonded magnet material 50a can no longer move, and above the temperature at which the bonded magnet material 50a is completely cured. By setting the reference temperature higher than the temperature at which the bonded magnet material 50a is completely cured, no interface is formed between multiple bonded magnets, and the multiple bonded magnets become firmly integrated. If the binder of the bonded magnet is nylon resin, the reference temperature is set higher than 80°C. If the binder of the bonded magnet is PPS (polyphenylene sulfide) resin, the reference temperature is set higher than 90°C.

[0075] The injection process is performed when the axial length CL is smaller than the magnet length ML of the ring magnet 50 in the cylindrical axis direction A1 (see Figure 2). The injection process is performed in the modification process when the length in the cylindrical axis direction A1 of the region of the cavity 71 that is not filled with bonded magnet material 50a is smaller than the magnet length ML of the ring magnet 50.

[0076] In the manufacturing method of this embodiment, the modification step includes a first modification step and a second modification step. The modification step further includes a third modification step and a fourth modification step. The injection step includes a first injection step and a second injection step. The injection step further includes a third injection step and a fourth injection step. In the manufacturing method of the ring magnet 50, first in the modification step, the axial length CL of the cavity 71 is adjusted to an initial length. Thereafter, the injection step and the modification step are performed alternately.

[0077] Specifically, the first injection process is performed after the first modification process. The second modification process is performed after the first injection process. The second injection process is performed after the second modification process. The third modification process is performed after the second injection process. The third injection process is performed after the third modification process. The fourth modification process is performed after the third injection process. The fourth injection process is performed after the fourth modification process.

[0078] Each step will be explained in order, referring to Figures 2 and 7 through 9. As shown in Figure 7, in the first modification step, the axial length CL is set to the first length L1. The first length L1 is smaller than the magnet length ML of the ring magnet 50 in the cylindrical axis direction A1. The first length L1 is less than or equal to the orientation length HL of the magnetic field generating unit 80. In this embodiment, the first length L1 is equal to the orientation length HL of the magnetic field generating unit 80.

[0079] The first length L1 is, for example, smaller than the width CW of the cavity 71 in the radial direction A3 of the cavity 71.

[0080] In the first injection step, bonded magnet material 50a is injected into the cavity 71. The bonded magnet material 50a injected in the first injection step fills a first region of the cavity 71 with a length A1 in the axial direction of the cylinder and a length L1. As shown by the arrows in Figure 7, the bonded magnet material 50a flows in the circumferential direction A2 and the radial direction A3.

[0081] As shown in Figure 8, the second modification step is performed based on the fact that the temperature of the bonded magnet material 50a injected in the first injection step falls below the reference temperature. The first ring magnet portion 51 is formed by the curing of the bonded magnet material 50a in the first region. The first magnet length ML1 of the first ring magnet portion 51 is equal to the first length L1 (see Figure 2).

[0082] In the second modification step, the axial length CL is increased by the second length L2. The second length L2 is smaller than the magnet length ML of the ring magnet 50 in the cylindrical axis direction A1. The second length L2 is less than or equal to the orientation length HL of the magnetic field generating unit 80. In this embodiment, the second length L2 is equal to the orientation length HL of the magnetic field generating unit 80. In the second modification step, the axial length CL of the cavity 71 is the sum of the first length L1 and the second length L2.

[0083] The second length L2 is, for example, smaller than the width CW of the cavity 71 in the radial direction A3 of the cavity 71.

[0084] In the second injection step, bonded magnet material 50a is injected into the cavity 71. The bonded magnet material 50a injected in the second injection step fills a second region of the cavity 71 where the length A1 in the cylindrical axis direction is equal to the second length L2. As shown by the arrows in Figure 8, the bonded magnet material 50a flows in the circumferential direction A2 and the radial direction A3.

[0085] The second ring magnet portion 52 is formed when the bonded magnet material 50a in the second region hardens. At the start of the second injection process, the first ring magnet portion 51 is not completely hardened, and the area near the end face is melted. As a result, the bonded magnet material 50a in the second region melts with the end face of the first ring magnet portion 51, and the second ring magnet portion 52 is formed integrally with the first ring magnet portion 51.

[0086] As shown in Figure 9, the third modification step is performed based on the fact that the temperature of the bonded magnet material 50a injected in the second injection step falls below the reference temperature. As the bonded magnet material 50a in the second region hardens, the second ring magnet portion 52 is formed so as to overlap with the first ring magnet portion 51 in the cylindrical axis direction A1. The second magnet length ML2 of the second ring magnet portion 52 is equal to the second length L2 (see Figure 2).

[0087] In the third modification step, the axial length CL is increased by the third length. The third length L3 is smaller than the magnet length ML of the ring magnet 50 in the cylindrical axis direction A1. The third length L3 is less than or equal to the orientation length HL of the magnetic field generating unit 80. In this embodiment, the third length L3 is equal to the orientation length HL of the magnetic field generating unit 80. In the third modification step, the axial length CL of the cavity 71 is the sum of the first length L1, the second length L2, and the third length L3.

[0088] In the third injection step, bonded magnet material 50a is injected into the cavity 71. The bonded magnet material 50a injected in the third injection step fills a third region of the cavity 71 where the length in the cylindrical axis direction A1 is equal to the third length L3. As shown by the arrows in Figure 9, the bonded magnet material 50a flows in the circumferential direction A2 and the radial direction A3.

[0089] The third ring magnet portion 53 is formed when the bonded magnet material 50a in the third region hardens. In the third injection step, the second ring magnet portion 52 is not completely hardened, and the area near the end face is melted. As a result, the bonded magnet material 50a in the third region melts with the end face of the second ring magnet portion 52, and the third ring magnet portion 53 is formed integrally with the second ring magnet portion 52.

[0090] Based on the fact that the temperature of the bonded magnet material 50a injected in the third injection step falls below the reference temperature, the fourth modification step is performed. In the fourth modification step, the axial length CL is made equal to the magnet length ML of the ring magnet 50.

[0091] In the fourth injection step, bonded magnet material 50a is injected into the cavity 71. The bonded magnet material 50a injected in the fourth injection step fills the fourth region of the cavity 71 that is not filled with bonded magnet material. The fourth ring magnet portion 54 is formed as the bonded magnet material 50a in the fourth region hardens.

[0092] The removal process is performed after the modification process and the injection process. In the removal process, the ring magnet 50 is removed from the mold 60. The magnetization process is performed after the removal process. In the magnetization process, the ring magnet 50 is magnetized. Before magnetizing the ring magnet 50, the ring magnet 50 may be demagnetized.

[0093] <Operation of the Embodiment> The first operation of this embodiment will now be described. In this embodiment, the bonded magnet material 50a is injected when the axial length CL of the cavity 71 is smaller than the magnet length ML of the ring magnet 50. This makes it more difficult for the bonded magnet material 50a to flow in the cylindrical axis direction A1 compared to when the axial length CL of the cavity 71 is equal to the magnet length ML of the ring magnet 50. Since the flow of the bonded magnet material 50a in the cylindrical axis direction A1 is suppressed, the orientation of the magnetic powder in the cylindrical axis direction A1 due to the flow of the bonded magnet material 50a is suppressed.

[0094] The second operation of this embodiment will now be described. By suppressing the orientation of the bonded magnet material 50a in the cylindrical axis direction A1, the orientation rate of the magnetic powder in the circumferential direction A2 and radial direction A3 can be improved. Since the magnetic flux of the magnetic field generating unit 80 is formed to align with the circumferential direction A2 and radial direction A3, the easy magnetization axis of the magnetic powder tends to align with the magnetic flux of the magnetic field generating unit 80. In particular, the above effect is easily obtained in regions within the cavity 71 where the orientation due to the flow of the bonded magnet material 50a has a stronger influence than the orientation due to the magnetic field of the magnetic field generating unit 80. An example of such a region is the area near the outer circumferential surface of the cavity 71, which is far from the magnetic poles of the magnetic field generating unit 80.

[0095] <Effects of the Embodiment> The effects of this embodiment will now be explained. (1-1) A mold 60 is used in the manufacturing method of the ring magnet 50. The mold 60 comprises a mold body 70. The mold body 70 has a cylindrical cavity 71. The mold 60 is configured to allow the axial length CL of the cavity 71 in the cylindrical axis direction A1 to be changed. The manufacturing method of the ring magnet 50 includes an injection step and a modification step. In the injection step, bonded magnet material 50a containing magnetic powder is injected into the cavity 71. In the modification step, the axial length CL is increased. The length of the magnetic powder in a second direction perpendicular to the easy magnetization axis is longer than the length in a first direction along the easy magnetization axis. The injection step is performed when the axial length CL is smaller than the magnet length ML of the ring magnet 50 in the cylindrical axis direction A1.

[0096] In this configuration, the bonded magnet material 50a is injected into the cavity 71 when the axial length CL of the cavity 71 is smaller than the magnet length ML in the cylindrical axis direction A1 of the ring magnet 50 that will be ultimately manufactured. The smaller the axial length CL of the cavity 71, the more the flow of the bonded magnet material 50a in the cylindrical axis direction A1 is suppressed, so that the easy magnetization axis of the magnetic powder of the bonded magnet material 50a is more likely to be aligned with the circumferential direction A2 and radial direction A3 of the cavity 71. Therefore, the magnetic force of the ring magnet 50 can be increased.

[0097] (1-2) The modification process includes a first modification process and a second modification process. In the first modification process, the axial length CL is set to a first length L1. In the second modification process, the axial length CL is increased by a second length L2. The injection process includes a first injection process and a second injection process. In the first injection process, bonded magnet material 50a is injected into the cavity 71. In the second injection process, bonded magnet material 50a is injected into the cavity 71. In the method for manufacturing the ring magnet 50, the first injection process is performed after the first modification process. In the method for manufacturing the ring magnet 50, the second modification process is performed after the first injection process. In the method for manufacturing the ring magnet 50, the second injection process is performed after the second modification process.

[0098] In this configuration, a bonded magnet with a length of first length L1 in the cylindrical axis direction A1 is formed in the first injection step, and a bonded magnet with a length of second length L2 in the cylindrical axis direction A1 is formed in the second injection step. Since the first length L1 and the second length L2 are smaller than the magnet length ML of the ring magnet 50 that is finally manufactured, the easy magnetization axis of the magnetic powder of the bonded magnet material 50a injected in each injection step can be easily aligned in the circumferential direction A2 and the radial direction A3.

[0099] (1-3) The first length L1 or the second length L2 is smaller than the width CW of the cavity 71 in the radial direction A3 of the cavity 71.

[0100] With this configuration, the length of the bonded magnet formed in the cylindrical axis direction A1 during each injection process can be made smaller than the magnet width MW of the ring magnet 50 in the radial direction A3.

[0101] (1-4) The modification process includes a third modification process. In the third modification process, the axial length CL is increased by a third length. The injection process includes a third injection process. In the third injection process, bonded magnet material 50a is injected into the cavity 71. In the method for manufacturing the ring magnet 50, the third modification process is performed after the second injection process. In the method for manufacturing the ring magnet 50, the third injection process is performed after the third modification process.

[0102] This configuration allows for the manufacture of a ring magnet 50 composed of three bonded magnets.

[0103] (1-5) The mold 60 includes a magnetic field generating unit 80. The magnetic field generating unit 80 is positioned on the inner or outer circumferential surface side of the cavity 71 in the radial direction A3 of the cavity 71. The magnetic field generating unit 80 generates a magnetic field in the cavity. In the method for manufacturing the ring magnet 50, the second modification step is performed based on the temperature of the bonded magnet material 50a injected in the first injection step falling below a reference temperature. The reference temperature is set based on the temperature at which the bonded magnet material 50a hardens.

[0104] With this configuration, the bonded magnet material 50a injected in the first injection step hardens before the axial length CL of the cavity 71 is increased by the second length L2 in the second modification step. Therefore, when the bonded magnet material 50a is injected in the second injection step, the bonded magnet material 50a injected in the first injection step does not need to be oriented. In this way, the magnetic field generating unit 80 only needs to orient the unhardened bonded magnet material 50a in the cavity 71, so the size of the magnetic field generating unit 80 in the cylindrical axis direction A1 can be reduced.

[0105] (1-6) In the injection process, the bonded magnet material 50a is injected in a direction along the cylindrical axis A1.

[0106] With this configuration, the easy magnetization axis of the magnetic powder of the bonded magnet material 50a injected in the cylindrical axis direction A1 is more likely to align with the circumferential direction A2 and the radial direction A3.

[0107] (1-7) The ring magnet 50 is a cylindrical ring magnet 50. The ring magnet 50 has a cylindrical first ring magnet portion 51 and a cylindrical second ring magnet portion 52. The first ring magnet portion 51 and the second ring magnet portion 52 are bonded magnets. The second ring magnet portion 52 overlaps with the first ring magnet portion 51 in the cylindrical axis direction A1 of the ring magnet 50.

[0108] In this configuration, the ring magnet 50 is formed by the overlapping of two bonded magnets. Therefore, the magnetic force of the ring magnet 50 can be increased compared to the case where the ring magnet 50 is formed by a single bonded magnet.

[0109] (1-8) The ring magnet 50 has a cylindrical third ring magnet portion 53. The third ring magnet portion 53 is a bonded magnet. The third ring magnet portion 53 overlaps with the second ring magnet portion 52 in the cylindrical axis direction A1.

[0110] According to this configuration, a ring magnet 50 can be constructed using three or more bonded magnets.

[0111] (1-9) The second ring magnet section 52 is integrated with the first ring magnet section 51.

[0112] With this configuration, the first ring magnet section 51 and the second ring magnet section 52 are integrated, which improves the handling of the ring magnet 50.

[0113] (1-10) The rotor 40 is equipped with a ring magnet 50.

[0114] This configuration allows for the construction of a rotor 40 using a ring magnet 50 with high magnetic force.

[0115] (1-11) The motor 20 comprises a rotor 40 and a stator 30.

[0116] With this configuration, the magnetic force of the ring magnet 50 of the rotor 40 is improved, which in turn improves the rotational characteristics of the motor 20, such as rotational torque and rotational accuracy.

[0117] (1-12) The blower 1 comprises a motor 20 and a blower device 10 driven by the motor 20.

[0118] With this configuration, the blower 10 is driven by the motor 20, which has improved rotational characteristics, thus providing an appropriate rotational force for the fluid machine.

[0119] <Second Embodiment> Referring to Figure 10, the blower 1, motor 20, rotor 40, ring magnet 50, and the method for manufacturing the ring magnet 50 according to the second embodiment will be described. Components in this embodiment that are common with the first embodiment are denoted by the same reference numerals as in the first embodiment, and redundant explanations are omitted.

[0120] In the manufacturing method of the ring magnet 50 of the first embodiment, the injection step and the modification step were performed alternately, but in the manufacturing method of the ring magnet 50 of this embodiment, the injection step and the modification step are performed simultaneously.

[0121] As shown in Figure 10, the mold body 70 of this embodiment has, for example, an elastic part 74 instead of the adjustment part 73 in the first embodiment. The elastic part 74 supports the bottom part 72 in the recess of the mold body 70. The elastic part 74 biases the bottom part 72 in the cylindrical axis direction A1 so that it moves from the internal region of the cavity 71 toward the opening 71b. The elastic part 74 deforms in the cylindrical axis direction A1. The elastic part 74 is, for example, a spring such as a coil spring or a leaf spring.

[0122] The elastic portion 74 supports the bottom portion 72 such that the bottom surface 71a of the cavity 71 is in its initial position. The initial position of the bottom surface 71a of the cavity 71 is the same as the position of the magnetic field generating portion 80 in the cylindrical axis direction A1. In the example of Figure 10, the bottom surface 71a of the cavity 71 and the movable portion 90 are separated in the cylindrical axis direction A1 at the initial position, but the bottom surface 71a of the cavity 71 and the movable portion 90 may be in contact at the initial position.

[0123] The injection process of this embodiment includes a first injection process and a second injection process. In the first injection process, bonded magnet material 50a is injected into the cavity 71 (see Figure 7). The cavity 71 is filled with bonded magnet material 50a. The bonded magnet material 50a injected in the first injection process is in the same position as the magnetic field generating section 80 in the cylindrical axis direction A1.

[0124] A second injection step is performed based on the fact that the bonded magnet material 50a injected in the first injection step falls below a reference temperature. In the second injection step, for example, the same amount of bonded magnet material 50a as injected in the first injection step is injected into the cavity 71.

[0125] In this embodiment, the modification process is carried out by increasing the axial length CL of the cavity 71 due to the pressure at which the bonded magnet material 50a is injected in the second injection step. Specifically, the elastic part 74 deforms due to the pressure at which more bonded magnet material 50a is injected into the cavity 71 which is filled with bonded magnet material 50a. As the bottom 72 of the cavity 71 moves in the cylindrical axis direction A1 due to the deformation of the elastic part 74, the axial length CL of the cavity 71 increases.

[0126] Based on the fact that the bonded magnet material 50a injected in the second injection step falls below a reference temperature, the second injection step is performed again. The second injection step is repeated until the axial length CL of the cavity 71 becomes the magnet length ML of the ring magnet 50.

[0127] <Effects of the Embodiment> The effects of this embodiment will now be explained. (2) In the method for manufacturing the ring magnet 50, the injection step and the modification step are performed simultaneously.

[0128] In this configuration, the bonded magnet material 50a is injected into the cavity 71, and the axial length CL of the cavity 71 increases. The axial length CL of the cavity 71 when the bonded magnet material 50a is injected into the cavity 71 is smaller than the length of the ring magnet 50 in the cylindrical axis direction A1 that is ultimately manufactured. Therefore, the easy magnetization axis of the magnetic powder of the bonded magnet material 50a formed in each injection step can be easily aligned in the circumferential direction A2 and the radial direction A3.

[0129] <Variation> The blower 1, motor 20, rotor 40, ring magnet 50, and method for manufacturing the ring magnet 50 of this disclosure may also be modified in ways other than those described above, such as those shown below, or in combination of at least two mutually non-inconsistent modifications.

[0130] As shown in Figure 11, the permanent magnets of the magnetic field generating unit 80 may be arranged in a Halbach array. In the example in Figure 11, the magnetic field generating unit 80 is constructed by combining a first magnet 80a, whose magnetic poles face radially A3, with a second magnet 80b, whose magnetic poles face cylindrical axis A1. The first magnet 80a is arranged in the circumferential direction A2 of the magnetic field generating unit 80. The second magnet 80b is arranged so as to be in contact with the end face of the first magnet 80a in cylindrical axis A1. This configuration can improve the strength of the magnetic field of the magnetic field generating unit 80.

[0131] As shown in Figure 12, the orientation length HL of the magnetic field generating section 80 in the cylindrical axis direction A1 may be made greater than the first length L1. With this configuration, the magnetic powder on the side facing the bottom surface 71a of the cavity 71 can be more reliably oriented among the bonded magnets formed in each injection step.

[0132] The second length L2 of the second ring magnet section 52 may be different from the first length L1 of the first ring magnet section 51. The third length L3 of the third ring magnet section 53 may be different from the second length L2 of the second ring magnet section 52.

[0133] The ring magnet 50 may be composed of two, three, or five or more bonded magnets.

[0134] The ring magnet 50 may be composed of, for example, seven layers of bonded magnets. In this modified example, the magnet length ML of the ring magnet 50 in the cylindrical axis direction A1 is, for example, 42 mm or more and 49 mm or less. The length of each bonded magnet in one layer in the cylindrical axis direction A1 is 6 mm or more and 7 mm or less.

[0135] In each embodiment, the gate 93 is located near the middle of the radial A3 of the cavity 71 when viewed from the cylindrical axis direction A1, and at the same position as the magnetic pole of the magnetic field generating unit 80 in the circumferential direction A2. The position of the gate 93 is not limited to this arrangement. The gate 93 may be located near the inner or outer circumferential surface of the cavity 71. The gate 93 may be located at a position different from the magnetic pole of the magnetic field generating unit 80 in the circumferential direction A2.

[0136] In each embodiment, no interface is formed between the first ring magnet portion 51 and the second ring magnet portion 52, but an interface may be formed. In this modified example, the reference temperature for initiating the modification process is set based on the temperature at which the bonded magnet material 50a is completely cured.

[0137] In each embodiment, the bonded magnet material 50a was injected in the direction along the cylindrical axis A1 during the injection process, but the bonded magnet material 50a may also be injected in the direction along the circumferential direction A2 or the radial direction A3. This configuration further reduces the amount of magnetic powder oriented in the cylindrical axis A1 due to the flow of the bonded magnet material 50a.

[0138] In each embodiment, the modification step was performed based on the temperature of the bonded magnet material 50a injected in the injection step falling below the reference temperature. However, the modification step may also be performed based on the elapsed reference period after the injection step. The reference period is set based on the period from the injection of the bonded magnet material 50a until the temperature of the bonded magnet material 50a reaches the reference temperature.

[0139] In the manufacturing method of the ring magnet 50, the magnetization step may be omitted. In this modified example, the ring magnet 50 may be magnetized during the molding step.

[0140] The magnetic field generating unit 80 may be omitted from the mold 60. In this modified example, during the molding process, the magnetic powder is oriented solely by the flow of the bonded magnet material 50a within the cavity 71.

[0141] The motor 20 may be of the inner rotor type. In this modified example, two or more magnetic poles are arranged on the outer surface of the ring magnet 50. In this modified example, the magnetic field generating unit 80 is located on the outer surface side of the cavity 71 in the radial direction A3.

[0142] The motor 20 may be used to drive the fan of a blower installed in the outdoor unit of an air conditioner.

[0143] The refrigeration system may include a motor 20. Examples of refrigeration systems include the air conditioner, water heater, chiller unit, and cooling system for cooling the air inside a storage area. The air inside a storage area refers to the air inside a refrigerator, freezer, display case, container, etc. These refrigeration systems include a compressor. The motor 20 is used as the motor for the compressor of the refrigeration system. With this configuration, the refrigeration system can be stably driven by the motor 20, which has improved rotational characteristics. [Explanation of symbols]

[0144] 1...Blower, 10...Blowering device, 20...Motor, 30...Stator, 40...Rotor, 50...Ring magnet, 50a...Bonded magnet material, 51...First ring magnet section, 52...Second ring magnet section, 53...Third ring magnet section, 60...Mold, 70...Mold body, 71...Cavity, 80...Magnetic field generating section.

Claims

1. A method for manufacturing a ring magnet (50), A mold (60) comprising a mold body (70) having a cylindrical cavity (71), wherein the axial length (CL) of the cavity (71) in the cylindrical axis direction (A1) can be changed, An injection step in which a bonded magnet material (50a) containing magnetic powder is injected into the cavity (71), The process includes a modification step of increasing the axial length (CL), The magnetic powder has a length in a second direction perpendicular to the easy magnetization axis that is longer than the length in a first direction along the easy magnetization axis. The injection step is performed when the axial length (CL) is smaller than the length (ML) of the ring magnet (50) in the cylindrical axis direction (A1). A method for manufacturing ring magnets.

2. The aforementioned modification process is, A first modification step in which the axial length (CL) is set to a first length (L1), The process includes a second modification step of increasing the axial length (CL) by a second length (L2), The injection step is, A first injection step in which the bonded magnet material (50a) is injected into the cavity (71), The process includes a second injection step of injecting the bonded magnet material (50a) into the cavity (71), After the first modification step, the first injection step is performed. After the first injection step, the second modification step is performed. After the second modification step, the second injection step is performed. A method for manufacturing a ring magnet according to claim 1.

3. The first length (L1) or the second length (L2) is smaller than the width (CW) of the cavity (71) in the radial direction (A3) of the cavity (71). A method for manufacturing a ring magnet according to claim 2.

4. The modification step includes a third modification step of increasing the axial length (CL) by a third length (L3), The injection step includes a third injection step of injecting the bonded magnet material (50a) into the cavity (71), After the second injection step, the third modification step is performed. After the third modification step, the third injection step is performed. A method for manufacturing a ring magnet according to claim 2.

5. The mold (60) is positioned on the inner or outer circumferential side of the cavity (71) in the radial direction (A3) of the cavity (71), and includes a magnetic field generating unit (80) that generates a magnetic field within the cavity (71). The second modification step is performed based on the fact that the temperature of the bonded magnet material (50a) injected in the first injection step falls below the reference temperature. The reference temperature is set based on the temperature at which the bonded magnet material (50a) hardens. A method for manufacturing a ring magnet according to any one of claims 2 to 4.

6. The injection step and the modification step are performed simultaneously. A method for manufacturing a ring magnet according to claim 1.

7. In the injection step, the bonded magnet material (50a) is injected in a direction along the cylindrical axis direction (A1). A method for manufacturing a ring magnet according to claim 1.

8. A cylindrical ring magnet (50), A cylindrical first ring magnet section (51) and It has a cylindrical second ring magnet portion (52), The first ring magnet portion (51) and the second ring magnet portion (52) are bonded magnets, The second ring magnet portion (52) overlaps with the first ring magnet portion (51) in the cylindrical axis direction (A1) of the ring magnet (50), Ring magnet.

9. It has a cylindrical third ring magnet section (53), The third ring magnet portion (53) is a bonded magnet, The third ring magnet portion (53) overlaps with the second ring magnet portion (52) in the direction of the cylindrical axis (A1), The ring magnet according to claim 8.

10. The second ring magnet portion (52) is integrated with the first ring magnet portion (51). The ring magnet according to claim 8.

11. A ring magnet (50) according to any one of claims 8 to 10, Rotor.

12. A rotor (40) and a stator (30) as described in claim 11, Motor.

13. The invention comprises a motor (20) as described in claim 12, and a blower (10) driven by the motor (20), Blower.

14. The motor (20) according to claim 12, Refrigeration equipment.

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