CN104067483B - Synchronous motor - Google Patents

Abstract

The invention provides a rotor of a synchronous motor, comprising: a permanent magnet (1) with high magnetic force, which is ring-shaped, arranged on the surface of the rotor, and the outer peripheral surface is opposite to the stator core (4); and the permanent magnet (2), It is ring-shaped, has a lower magnetic force than the permanent magnet (1), and is polar anisotropically oriented, and surrounds both ends and the inner peripheral surface side of the permanent magnet (1) in the direction of the rotation axis on its outer peripheral surface A permanent magnet (1) is embedded in the way, and its length in the direction of the rotation axis is longer than that of the stator core (4).

Description

synchronous motor

technical field

The invention relates to a synchronous motor.

Background technique

When a high-magnetism magnet is used for the rotor of a synchronous motor, since the rare earth magnet is a very expensive material, it is often used in a shape as thin as possible in order to suppress its usage. In addition, in the case of a motor used for a blower, since the vane is directly attached to the rotating shaft of the motor, if the output torque of the motor pulsates, the vane will cause noise. Compared with the embedded magnet (IPM: Interior Permanent Magnet) structure, which tends to generate torque ripple, the structure in which the magnet is arranged on the surface of the rotor (SPM: Surface Permanent Magnet) is often used. The rotor in this case generally adopts the following structure: soft magnetic materials such as iron are used as the back yoke, and thin ring magnets or arc-shaped shoe-shaped magnets are arranged on the rotor surface (for example, patent documents 1 and 2).

In addition, in the case of a flat motor whose outer diameter is larger than the axial dimension, when the axial length of the rotor is larger than the lamination thickness of the stator core, the portion of the rotor that does not face the stator core The amount of magnetic flux linked to the stator greatly affects the characteristics of the motor, so in many cases, the axial dimension of the permanent magnet of the rotor is set to be larger than the lamination thickness of the stator core.

However, if the axial dimension of the permanent magnet is larger than that of the stator core, there will be many non-magnetic spaces (air) on the surface of the magnet at the part that does not face the stator core, and the magnetic permeability of the magnet will decrease, resulting in magnet generation magnetic force drops. In the case of a rotor using a rare-earth magnet, since thinner permanent magnets are used, the above-mentioned decrease in magnetic force due to a decrease in magnetic permeability is greater. Therefore, even if the length of the permanent magnet in the rotor axial direction is increased with respect to the lamination thickness of the stator, the effect is small relative to the increase in material cost.

There are cases where rotors are composed of a plurality of different structures or magnet materials in the axial direction, and there are rotors using rare earth sintered magnets and ferrite sintered magnets with high magnetic force (for example, Patent Documents 3 and 4). Rare earth sintered magnets are often manufactured by sintering a large magnet block and then cutting it into a predetermined shape. Therefore, in order to reduce the manufacturing cost of the magnet, it is often used in a flat plate shape. Therefore, when used in the rotor of a synchronous motor, the IPM method in which magnet insertion holes are provided in the soft magnetic iron core and permanent magnets are arranged inside the rotor is often used. In addition, ferrite sintered magnets are often used in IPM structure in order to prevent magnets from flying due to centrifugal force in applications such as high rotation frequency.

However, in the case of the rotor of the IPM structure, since there is a soft magnetic material as an iron core between adjacent magnetic poles, there is a large amount of magnetic flux passing through the portion and short-circuiting the adjacent magnetic poles. In the case of a ferrite sintered magnet, since its magnetic force is lower than that of a rare-earth sintered magnet, the influence of a short-circuit of magnetic flux between magnetic poles is greater than that of a rare-earth magnet. When they are arranged at both ends in the rotor axial direction that do not face the stator core, since the outside of the rotor surface is air, the magnetic resistance increases, the magnetic permeability decreases, and the magnetic flux generated from the magnet decreases. The short-circuited magnetic flux between the magnetic poles inside the rotor is not greatly affected by the presence or absence of the stator core, so the short-circuited magnetic flux changes little. The proportion of the increase, it is difficult to effectively use the magnetic force of the magnet.

In order to improve the performance of the rotor, rare-earth magnets with higher magnetic force may be used, but since the material is expensive, there is a method of incorporating rare-earth magnets into a part of the rotor composed of low-magnetic-force magnets (for example, patent Literature 5, 6).

However, in the case of the structure described in Patent Document 5, since it is necessary to prevent the back yoke of the stator from being magnetically saturated by the high-force permanent magnets from leaking the magnetic flux to the outside of the motor, such a high magnetic force cannot be obtained. In addition, in the case of adopting the structure described in Patent Document 6, since a part of the magnetic force in the circumferential direction is enhanced by the high-magnetism magnet, the distribution waveform of the magnetic flux density on the rotor surface is greatly distorted, and it is easy to generate a fault when the motor is running. Torque ripple causes vibration and noise.

Patent Document 7 describes a rotor that achieves high performance by combining low-magnetic-force magnets and high-magnetic-force magnets. A magnet with low magnetic force is used inside the rotor, but the magnet has polar anisotropic orientation, and due to the effect of concentrating magnetic flux near the center of the magnetic pole, even a magnet with low magnetic force can obtain high magnetic force. A magnet with high magnetic force is arranged on the outer periphery of the magnet, that is, on the surface of the rotor. For high-magnetism magnets such as rare earth magnets, since the material is expensive, thinner high-magnetism magnets are usually used in order to suppress the amount of use. Magnet material, so the permeability of the magnet with high magnetic force will be reduced, and it will not be able to obtain enough magnetic force. In the case of such a rotor, by arranging magnets with anisotropic polarity inside, it is possible to compensate for the drop in magnetic force of the high-magnetic-force magnets and obtain high magnetic force.

However, as mentioned above, it is difficult to obtain sufficient magnetic force in a state where the magnetic permeability is low for thin high-strength magnets. In the case of a stator), generally, the increase in magnetic force corresponding to the increase in size cannot be obtained, and the cost performance decreases.

Patent Document 1: Japanese Patent Laid-Open No. 2005-312166

Patent Document 2: Japanese Patent Laid-Open No. 2009-142144

Patent Document 3: Japanese Unexamined Patent Publication No. 2005-304204

Patent Document 4: Japanese Patent Laid-Open No. 2010-68600

Patent Document 5: Japanese Utility Model Publication No. 7-3278

Patent Document 6: Japanese Patent Application Laid-Open No. 9-205746

Patent Document 7: Japanese Patent Laid-Open No. 2011-87393

Contents of the invention

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a synchronous motor capable of obtaining sufficient magnetic flux even if the amount of expensive high-magnetism magnets used is reduced.

In order to solve the above problems and achieve the purpose of the invention, the synchronous motor involved in the present invention is characterized in that it includes: a rotor, and the rotor includes: a first permanent magnet, which is ring-shaped, and is arranged on the surface of the rotor; and a second permanent magnet, It has a ring shape, has lower magnetic properties than the first permanent magnet, and is arranged on its outer peripheral surface so as to surround both ends of the first permanent magnet in the direction of the rotation axis and the inner peripheral surface side. The first permanent magnet; and a stator, the stator includes: a stator core, the stator core is opposite to the outer peripheral surface of the first permanent magnet, the length of the stator core in the direction of the rotation axis longer than the length of the first permanent magnet in the direction of the rotation axis and shorter than the length of the second permanent magnet in the direction of the rotation axis, the second permanent magnet being formed to be in contact with the rotor Multiple poles correspond to polar anisotropic orientations.

According to the present invention, there is an effect that a sufficient amount of magnetic flux can be obtained even if the usage-amount of the expensive high-magnetic-force first permanent magnet is reduced.

In addition, by orienting the second permanent magnet into polar anisotropy that enables the magnetic flux to concentrate at the center of the magnetic pole, it is possible to obtain more magnetic flux although the magnetic force is lower. In addition, by increasing the thickness of the second permanent magnet, even if the distance from the stator is long, it is possible to suppress a decrease in magnetic flux density and obtain magnetic flux more efficiently.

Description of drawings

FIG. 1 is a longitudinal sectional view showing the configuration of a synchronous motor using a rotor according to Embodiment 1. FIG.

Fig. 2 is an A-A cross-sectional view of the rotor in Fig. 1 .

Fig. 3 is a B-B cross-sectional view of the rotor in Fig. 1 .

FIG. 4 is a diagram comparing the induced voltage of the rotor 6 according to Embodiment 1 with the induced voltage of a rotor according to a conventional structure.

FIG. 5 is a diagram illustrating a method of manufacturing a rotor according to Embodiment 2. FIG.

FIG. 6 is a diagram showing a method of manufacturing a rotor according to Embodiment 3. FIG.

FIG. 7 is a diagram illustrating a method of manufacturing a rotor according to Embodiment 4. FIG.

Symbol Description

1, 1a, 2, 2a～2f permanent magnet

3 stator

4 stator core

5 windings

6 rotors

7 axis of rotation

detailed description

Hereinafter, embodiments of the synchronous motor according to the present invention will be described in detail based on the drawings. In addition, this invention is not limited to the following embodiment.

Embodiment 1

The rotor of the synchronous motor according to this embodiment will be described. FIG. 1 is a longitudinal sectional view showing the configuration of a synchronous motor using a rotor according to the present embodiment. Fig. 2 is an A-A cross-sectional view of the rotor in Fig. 1 . Fig. 3 is a B-B cross-sectional view of the rotor in Fig. 1 . The A-A cross section and the B-B cross section are cross sections perpendicular to the rotation axis direction of the rotor. The synchronous motor according to this embodiment includes: a stator 3 having an annular shape; and a rotor 6 , which is rotatably arranged inside the stator 3 and has a rotating shaft 7 at its center.

The stator 3 includes: a ring-shaped stator core 4 formed by laminating electromagnetic steel sheets; and a winding 5 wound around the stator core 4 . Inside the stator core 4, the rotor 6 is rotatably arranged. In the stator core 4, a plurality of teeth (not shown) are provided along the entire circumferential direction on its inner peripheral side, which are protruding core parts, and grooves (not shown) as spaces between the teeth are provided. ) is wound with a winding 5 for applying current from the outside. The winding 5 is wound intensively on each tooth portion.

The rotor 6 includes two types of permanent magnets 1 and 2 having different magnetic properties. Here, the permanent magnet 1 (first permanent magnet) refers to a high-magnetic permanent magnet, for example, a bonded magnet in which a rare earth magnet and resin are mixed, and a material such as NdFeB or SmFeN is used for the rare earth magnet. In addition, materials such as nylon, PPS (Polyphenylene sulfide, polyphenylene sulfide) or epoxy resin are used as the resin material. The permanent magnet 2 (second permanent magnet) is a permanent magnet with low magnetic force, for example, a bonded magnet obtained by mixing a ferrite magnet and a resin is used. The resin material used therein is the same as the above-mentioned resin material. The axial length of the rotor 6 (the axial length of the rotating shaft 7 ) is larger than the lamination thickness of the stator 3 (the axial length of the stator core 4 ).

The arrangement structure of the permanent magnets 1 and 2 will be described with reference to FIGS. 1 to 3 . The permanent magnet 1 is annular, and its outer peripheral surface faces the stator core 4 . The axial length of the permanent magnet 1 is shorter than that of the stator core 4 . The permanent magnet 1 is surrounded by the permanent magnet 2 on both axial end surfaces and the inner peripheral surface. That is, in the vicinity of the axial center of the outer peripheral surface of the permanent magnet 2, a groove for housing the permanent magnet 1 is formed along the entire circumferential direction, and the permanent magnet 1 is arranged in the groove to become embedded in the outer peripheral surface of the permanent magnet 2. form. In addition, the permanent magnet 1 and the permanent magnet 2 are arranged coaxially. In this way, the permanent magnet 1 is arranged on the outer peripheral side of the ring-shaped permanent magnet 2 and near the center in the axial direction, and the permanent magnet 2 is arranged on both axial ends and the inner peripheral surface of the permanent magnet 1 . In addition, the permanent magnets 1, 2 form the same cylindrical outer peripheral surface of the rotor 6, and the outer peripheral surface of the rotor 6 is composed of the outer peripheral surface of the permanent magnet 1 and the outer periphery of the permanent magnet 2 sandwiching the outer peripheral surface in the axial direction. face composition.

As shown in FIG. 2 , the permanent magnet 1 has, for example, a non-uniform shape in which the thickness of the magnet varies corresponding to the magnetic poles of the rotor 6 . That is, by increasing the (radial) thickness near the center P of the magnetic pole to increase the magnetic force, and by reducing the thickness of the interpole Q, a larger magnetic flux can be obtained than a ring magnet having a uniform thickness. In addition, the orientation inside the magnet of the permanent magnet 1 is, for example, close to polar anisotropic orientation. The outer circumference of the permanent magnet 2 has a shape corresponding to the inner circumference of the permanent magnet 1 .

The permanent magnets 2 are, for example, formed in polar anisotropic orientation corresponding to the magnetic poles of the rotor 6 . Compared with the permanent magnet 2, the permanent magnet 1 is a thinner magnet. Since the soft magnetic iron core is not used as the back yoke, the magnetic permeability of the magnet is lower. In comparison, the magnetic flux generated on the rotor surface is lower. However, since the permanent magnet 2 exists inside the permanent magnet 1, the actual magnetic flux obtained on the rotor surface is the amount obtained by adding the magnetic fluxes generated by the permanent magnet 1 and the permanent magnet 2 respectively, and it is possible to obtain The performance of the structure of the body and the back yoke is similar. In addition, since the permanent magnet 2 is formed in polar anisotropic orientation, the effective thickness of the magnet constituting the magnetic pole is greater than the dimensional thickness (outer diameter-inner diameter), and even if the distance from the stator core 4 is long, the magnetic force of the magnet will be reduced. The conductivity also decreases less, and although the distance from the stator core 4 is longer, the magnetic flux decreases less.

If the permanent magnet 1 is arranged at a position that does not face the stator core 4, the outer side of the permanent magnet 1 is surrounded by non-magnetic material and air, so the magnetic resistance increases, the magnetic permeability decreases, and the magnetic flux appearing on the surface dramatically drop. Therefore, in the case of enlarging the axial dimension of the permanent magnet 1, although the dimension is increased, the increase in magnetic flux is small, and the cost performance is deteriorated.

Therefore, as shown in FIG. 3 , a structure consisting of only permanent magnets 2 is adopted at the axial end portion of the rotor 6 . The permanent magnets 2 are bonded magnets made of ferrite, for example, and are formed in polar anisotropic orientation corresponding to the magnetic poles of the rotor 6 . In FIG. 3 , the orientation directions of the polar anisotropy are shown by arrows. For the polar anisotropic magnet, since the effective thickness of the magnet can take a large value as mentioned above, a relatively large gap can also be generated on the rotor surface at the axial end of the rotor 6 that is not opposed to the stator core 4. flux.

As described above, in the present embodiment, in the structure of the synchronous motor, a magnet with a high magnetic force is arranged near the axial center of the rotor 6 where the magnet has a relatively high permeability and faces the stator core 4. The permanent magnet 1 is disposed near the axial end portion of the stator core 4 where the magnetic permeability is likely to decrease, and the permanent magnet 2 having a low magnetic force but having an anisotropic orientation of the polarity can be arranged, thereby obtaining a high magnetic force even at a reduced cost. The use amount of the permanent magnet 1 can also suppress the characteristic degradation of the synchronous motor.

Next, the operation of this embodiment will be described. FIG. 4 is a diagram comparing the induced voltage of the rotor 6 according to the present embodiment with the induced voltage of the rotor according to the conventional structure. Specifically, when the lamination thickness (L3) of the stator core 4 is set to 15 mm, the induced voltage obtained by the synchronous motor having the rotor 6 composed of a combination of the structures shown in FIG. 2 and FIG. The induced voltages obtained by conventional synchronous motors having only the rotor configured in the structure shown in FIG. 2 were compared. That is, the rotor according to the conventional structure has the structure shown in FIG. 2 in any cross section perpendicular to the axial direction, and the axial length of the permanent magnet 1 is equal to the axial length of the permanent magnet 2 .

In FIG. 4 , the horizontal axis represents the axial dimension of the structural portion shown in FIG. 2 , that is, the axial length of the permanent magnet 1 . Here, curves ( L1 , L2 ) are shown when the full axial length of the rotor 6 is fixed (18 mm) and the axial length of the permanent magnet 1 is taken on the horizontal axis. L1 denotes the rotor 6 of this embodiment, and L2 denotes a rotor according to a conventional configuration. In addition, since the axial dimension of the rotor is fixed, the dimension obtained by subtracting the axial dimension of the structural portion in FIG. 2 (that is, the axial length of the permanent magnet 1 ) from the fixed dimension is the dimension of the structural portion in FIG. 3 . In addition, in FIG. 4, it is assumed that the induced voltage obtained under the case where the lamination thickness (L3) of the stator core is the same as the axial length of the rotor involved in the conventional structure (that is, the intersection point of L2 and L3) is 100%, Let the vertical axis be the induced voltage ratio.

As shown in FIG. 4, in the rotor of the conventional structure, when the axial length of the rare-earth permanent magnet 1 and the stator core 4 are the same as 15mm, the induced voltage ratio is 100%. In the case of the rotor 6 according to the embodiment, the induced voltage ratio becomes 100% when the axial length of the rare-earth permanent magnet 1 is approximately 11 mm. Although the axial length of the rotor 6 is 3 mm longer, the volume of the permanent magnet 1 Compared with the existing structure, it is reduced by about 30%. Since the material unit price of the rare earth magnet (permanent magnet 1) and the ferrite magnet (permanent magnet 2) differ by more than 10 times, according to this embodiment, although the axial length of the rotor 6 increases, the amount of ferrite magnets used increases. , but from the perspective of the overall cost of materials, the cost reduction effect is large enough.

As described above, in the present embodiment, two types of magnets having different magnetic properties, that is, high-magnetic permanent magnets 1 (such as rare earth magnets) and low-magnetic permanent magnets 1 are arranged on the surface side of the rotor 6 facing the stator 3 . The permanent magnet 2 (such as a ferrite magnet) adopts a form in which the permanent magnet 1 is embedded in the vicinity of the axial center of the outer peripheral surface of the permanent magnet 2, so that it is arranged outside and radially inward of both axial ends of the permanent magnet 1. There is a permanent magnet 2, and the orientation of the permanent magnet 2 is polar anisotropic.

According to the present embodiment, it is possible to realize a rotor of a synchronous motor in which a sufficient amount of magnetic flux can be obtained while reducing the amount of expensive high-magnetic permanent magnets 1 (rare earth magnets) used to suppress the material cost of the motor.

In addition, by performing polar anisotropic orientation in which the magnetic flux can be concentrated at the center of the magnetic pole in the permanent magnet 2 , more magnetic flux can be obtained from the low magnetic force magnet. In addition, by increasing the thickness of the permanent magnet 2 , even if the distance from the stator 3 is long, it is possible to suppress a decrease in the magnetic flux density and obtain the magnetic flux of the permanent magnet 2 more efficiently.

In addition, in the case of a synchronous motor with a built-in drive circuit, if there is a soft magnetic material with high conductivity in the rotor, the high-frequency current (shaft current) generated by the drive circuit will easily pass through the stator core, rotor, and rotating shaft. The flow to the rolling bearing is likely to cause electrical corrosion (discharge). In the rotor 6 of this embodiment, since the rotor 6 does not need to use a soft magnetic material, it is possible to reduce the cause of the axial current flow.

Embodiment 2

FIG. 5 is a diagram illustrating a method of manufacturing the rotor according to the present embodiment. The configuration of the rotor of the present embodiment is the same as that of the rotor 6 of the first embodiment. That is, the rotor of the present embodiment is the rotor 6 constituted by a combination of the configurations of FIGS. 2 and 3 . The permanent magnets 1 and 2 may be bonded magnets, for example, as described in the first embodiment.

The permanent magnet 2 of FIG. 2 and the permanent magnet 2 of FIG. 3 may be the same material, so it is preferable to form them into one body, but the permanent magnet 2 has a concave space for arranging the permanent magnet 1 near the center of the axial direction. Therefore, there is a portion (concave portion) where the outer diameter becomes smaller. In this case, since the permanent magnet 2 cannot be taken out from the molding die, it is difficult to integrally mold the permanent magnet 2 . In addition, if the permanent magnet 1 is molded first, and then the permanent magnet 2 is integrally molded by insert molding, the thinner permanent magnet 1 may be crushed due to molding pressure from the inner diameter side during molding. Sex is higher.

Therefore, in this embodiment, the molding of the shape part of FIG. 2 and the shape part of FIG. 3 of the rotor 6 is performed separately. The details are as follows. First, the permanent magnet 1 and the ring-shaped permanent magnet 2a disposed inside are integrally molded, for example, by injection molding ( FIG. 5( a )). The permanent magnet 2a is made of the same material as the permanent magnet 2, and has the same magnetic properties. The permanent magnet 2 a corresponds to a portion of the permanent magnet 2 that is located on the inner peripheral surface side of the permanent magnet 1 and whose arrangement position in the axial direction overlaps with the permanent magnet 1 .

In addition, the ring-shaped permanent magnets 2b, 2c are individually molded, for example, by injection molding ( FIG. 5( a )). The permanent magnets 2b and 2c are made of the same material as the permanent magnet 2 and have the same magnetic properties. The permanent magnets 2b and 2c have the same cross-sectional shape, the inner diameter is equal to the inner diameter of the permanent magnet 2a, and the outer diameter is equal to the outer diameter of the permanent magnet 1 . The permanent magnet 2b corresponds to a part of the permanent magnet 2 that is arranged outside one end of the permanent magnet 1 in the axial direction, and the permanent magnet 2c corresponds to a part of the permanent magnet 2 that is arranged outside the other end of the permanent magnet 1 in the axial direction. .

Then, the permanent magnet 2a (the first magnet part) integrally formed with the permanent magnet 1 is sandwiched by the permanent magnet 2b (the second magnet part) and the permanent magnet 2c (the third magnet part) from both sides in the axial direction, so that they The rotors are superimposed and joined to each other in the axial direction, whereby a rotor having the same structure as the rotor 6 of Embodiment 1 can be manufactured ( FIG. 5( b )). In this case, the permanent magnet 2 is constituted by joining three permanent magnets 2a to 2c in the axial direction.

According to this embodiment, the permanent magnet 2 is divided into the permanent magnet 2a, the permanent magnet 2b, and the permanent magnet 2c, and the permanent magnet 1, the permanent magnet 2a, the permanent magnet 2b, and the permanent magnet 2c are separately molded and manufactured. The rotor 6 of Embodiment 1 can be manufactured.

In addition, since the permanent magnets 2a to 2c can be individually molded, polar anisotropic orientation suitable for each permanent magnet can also be individually applied, and the orientation magnetic field of the molding die can also be adjusted corresponding to each permanent magnet.

Embodiment 3

FIG. 6 is a diagram illustrating a method of manufacturing the rotor according to the present embodiment. The configuration of the rotor of the present embodiment is the same as that of the rotor 6 of the first embodiment. That is, the rotor of the present embodiment is the rotor 6 constituted by a combination of the configurations of FIGS. 2 and 3 . The permanent magnets 1 and 2 may be bonded magnets, for example, as described in the first embodiment.

The detailed production method is as follows. First, the permanent magnet 2d is integrally molded by injection molding ( FIG. 6( a )), and the permanent magnet 2d corresponds to a component obtained by integrally molding the permanent magnet 2a and the permanent magnet 2c described in the second embodiment. The permanent magnet 2d is made of the same material as the permanent magnet 2, and has the same magnetic properties. That is, the permanent magnet 2d is a member obtained by making the part of the permanent magnet 2 according to Embodiment 1 which is located on the inner peripheral surface side of the permanent magnet 1 and overlaps with the permanent magnet 1 in the axial direction (the first part ) is integrally formed with a portion (second portion) arranged outside one end of the permanent magnet 1 in the axial direction.

Then, the permanent magnet 1 and the permanent magnet 2d are integrally molded by insert molding so that the permanent magnet 1 is embedded in the first portion of the permanent magnet 2d ( FIG. 6( b )). In addition, the ring-shaped permanent magnet 2e is separately molded by injection molding, for example ( FIG. 6( b )). The permanent magnet 2e is made of the same material as the permanent magnet 2, and has the same magnetic properties. The inner diameter of the permanent magnet 2e is equal to the inner diameter of the permanent magnet 2d, and the outer diameter thereof is equal to the maximum outer diameter of the permanent magnet 1.

Then, the permanent magnet 2d (first magnet member) integrally formed with the permanent magnet 1 and the permanent magnet 2e (second magnet member) are superimposed in the axial direction and bonded to each other in such a manner that the permanent magnet 1 is arranged on the connection surface. Thereby, the rotor whose structure is the same as the rotor 6 of Embodiment 1 can be manufactured (FIG.6(b)). In this case, the rotor 6 can be manufactured from two components of the permanent magnet 2 d and the permanent magnet 2 e integrally formed with the permanent magnet 1 . The permanent magnet 2 is composed of a permanent magnet 2d and a permanent magnet 2e.

According to this embodiment, since the number of components constituting the permanent magnets 1 and 2 of the rotor 6 can be reduced to two, the number of components can be reduced, and the manufacturing process cost can be reduced.

Embodiment 4

FIG. 7 is a diagram illustrating a method of manufacturing the rotor according to the present embodiment. The configuration of the rotor of the present embodiment is the same as that of the rotor 6 of the first embodiment. That is, the rotor of the present embodiment is the rotor 6 constituted by a combination of the configurations of FIGS. 2 and 3 . The permanent magnets 1 and 2 may be bonded magnets, for example, as described in the first embodiment.

The detailed production method is as follows. First, the permanent magnet 2f is integrally molded by, for example, injection molding ( FIG. 7 ). Parts obtained by one-piece molding. The permanent magnet 2f is made of the same material as the permanent magnet 2, and has the same magnetic properties. That is, the permanent magnet 2f is formed by combining the parts of the permanent magnet 2 according to the first embodiment, which are located on the inner peripheral surface side of the permanent magnet 1 and overlap the permanent magnet 1 in the axial direction. The part behind the two halves and the part arranged outside one end of the permanent magnet 1 in the axial direction.

Then, the permanent magnet 1a and the permanent magnet 2f are integrally molded by insert molding to form a form in which the permanent magnet 1a is embedded in the permanent magnet 2f, wherein the permanent magnet 1a is obtained by dividing the permanent magnet 1 equally in the axial direction. One side (Figure 7). Two permanent magnets 2f in which the permanent magnets 1a are embedded are prepared in this way, and they are superimposed and joined in the axial direction so that the permanent magnets 1a serve as joining surfaces, whereby the rotor 6 having the same structure as the first embodiment can be manufactured. of the rotor (Figure 7). In this case, the rotor 6 can be manufactured from two parts. In addition, the permanent magnet 2 is composed of two permanent magnets 2f, and the permanent magnet 1 is composed of two permanent magnets 1a.

According to the present embodiment, since the number of components constituting the permanent magnets 1 and 2 of the rotor 6 can be reduced to two, it is possible to reduce manufacturing processing costs. In addition, since two parts of the same shape are combined, the same mold for molding the part can be used, the types of molds can be reduced, and the cost of the mold can be reduced.

As described above, the present invention is useful as a rotor of a synchronous motor.

Claims (6)

1. A synchronous motor, characterized in that, comprising: The rotor includes: a first permanent magnet in the shape of a ring and arranged on the surface of the rotor; and a second permanent magnet in the shape of a ring whose magnetic properties are lower than that of the first permanent magnet. The first permanent magnet is disposed on an outer peripheral surface so as to surround both ends of the first permanent magnet in the direction of the rotation axis and an inner peripheral surface side; and The stator includes: a stator core, the stator core is opposed to the outer peripheral surface of the first permanent magnet, and the length of the stator core in the direction of the rotation axis is longer than that of the first permanent magnet. The length in the direction of the rotation axis of the second permanent magnet is longer than the length in the direction of the rotation axis of the second permanent magnet, The second permanent magnet is formed in a polar anisotropic orientation corresponding to a plurality of magnetic poles of the rotor. 2. The synchronous motor according to claim 1, characterized in that: The thickness of the first permanent magnet at the center of the plurality of magnetic poles of the rotor is greater than that between the centers of the plurality of magnetic poles in a cross section perpendicular to the direction of the rotation axis. 3. The synchronous motor according to claim 1, characterized in that: The first permanent magnet is a rare earth magnet, The second permanent magnet is a ferrite magnet. 4. The synchronous motor according to claim 1, characterized in that: The rotor is configured by sandwiching and joining a first magnet member between a second magnet member and a third magnet member in the direction of the rotation axis, wherein, In the first magnet member, a portion of the second permanent magnet that is located on the inner peripheral surface side of the first permanent magnet and that overlaps with the first permanent magnet in the direction of the rotation axis and the The first permanent magnet is integrally formed, The second magnet member is a portion of the second permanent magnet that is disposed outside one end of the first permanent magnet in the direction of the rotation axis, and is molded separately from the first magnet member. , The third magnet member is a part of the second permanent magnet that is arranged outside the other end of the first permanent magnet in the direction of the rotation axis, and is connected to the first magnet member and the first permanent magnet. 2. The magnet parts are separately molded. 5. The synchronous motor according to claim 1, characterized in that: The rotor is constructed by joining a first magnet member and a second magnet member in the direction of the rotation axis, wherein, The first magnet member is embedded by inserting the first permanent magnet into the first part in a member formed by integrally molding the first part and the second part of the second permanent magnet. obtained by molding, wherein the first part is located on the inner peripheral surface side of the first permanent magnet among the second permanent magnets, and the arrangement position in the direction of the rotation axis overlaps with the first permanent magnet The second part is a part of the second permanent magnet that is arranged outside one end of the first permanent magnet in the direction of the rotation axis, The second magnet member is a portion of the second permanent magnet disposed outside the other end of the first permanent magnet in the direction of the rotation axis, and is molded separately from the first magnet member. get. 6. The synchronous motor according to claim 1, characterized in that: The rotor is constructed by joining a first magnet member and a second magnet member in the direction of the rotation axis, wherein, The first magnet member is formed by placing a portion of the second permanent magnet on the inner peripheral surface side of the first permanent magnet and overlapping with the first permanent magnet at an arrangement position in the direction of the rotation axis. A part that is divided into two halves in the direction of the rotation axis and a part of the second permanent magnet that is disposed outside one end of the first permanent magnet in the direction of the rotation axis and is integrally molded. Among them, the first permanent magnet is obtained by insert molding by inserting one of the two halves of the first permanent magnet in the direction of the rotation axis, The second magnet member is formed by placing a portion of the second permanent magnet on the inner peripheral surface side of the first permanent magnet and overlapping with the first permanent magnet at an arrangement position in the direction of the rotation axis. The other part divided into two in the direction of the rotation axis is integrally molded with a part of the second permanent magnet disposed outside the other end of the first permanent magnet in the direction of the rotation axis. Among the members, the first permanent magnet divided into two halves in the direction of the rotation axis is inserted into the other part to perform insert molding.