JP7251090B2 - permanent magnets and motors - Google Patents

Description

The present invention relates to permanent magnets and motors.

Permanent magnets attached to a rotor portion of a motor have conventionally generally been magnetized in a uniform direction. On the other hand, in Patent Document 1, an anisotropic segment-shaped magnet is used as a stator or an outer rotor for the purpose of preventing the cogging phenomenon of the motor and the vibration, noise, and uneven rotation caused by this without reducing the torque. is being considered.

Japanese Patent Application Laid-Open No. 2002-110417

2. Description of the Related Art In recent years, there has been a growing demand for improved motor efficiency, and adoption of embedded magnet motors (IPM motors) in which permanent magnets are embedded in a rotor is progressing. Further, in this magnet-embedded motor, use of rare earth magnets such as neodymium magnets is progressing in place of ferrite magnets.

In order to precisely control the direction of magnetization as described in Patent Document 1, a vertical magnetic field molding method generally used for ferrite magnets (compression molding method in which the direction of the magnetic field and the direction of pressure are parallel during molding) (Also called a parallel magnetic field molding method.). However, a transverse magnetic field molding method (a method of compression molding in which the direction of the magnetic field during molding is perpendicular to the direction of pressurization; also called vertical magnetic field molding) is generally used for the production of rare earth magnets. The reason for this is that when the vertical magnetic field forming method is applied to the production of rare earth magnets, only a lower residual magnetic flux density can be obtained than the horizontal magnetic field forming method. It is technically possible to precisely control the direction of magnetization by the transverse magnetic field forming method, but this will result in a significant decrease in productivity and an increase in cost.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a permanent magnet which can be manufactured at low cost and whose magnetic flux can be controlled, and a motor to which this permanent magnet is applied.

In order to achieve the above object, a permanent magnet according to one aspect of the present invention is a permanent magnet made of a rare earth magnet attached to a rotor of a motor, and is configured by combining a plurality of magnets having mutually different magnetization directions. and has an orientation control region in which the direction of magnetization is different from that of other regions along the longitudinal direction.

A motor according to one aspect of the present invention includes a rotor having a plurality of magnet insertion holes, and a plurality of permanent magnets made of rare earth magnets accommodated in the plurality of magnet insertion holes. Some of the permanent magnets are formed by combining a plurality of magnets with different magnetization directions, and have an orientation control region with a different magnetization direction from other regions along the longitudinal direction.

According to the above permanent magnet and motor, the magnetic flux of the permanent magnet attached to the rotor can be controlled by the permanent magnet having the orientation control region whose magnetization direction is different from that of other regions. Also, this permanent magnet is configured by combining a plurality of magnets with mutually different orientations. Therefore, the control of the magnetic flux in the permanent magnet can be realized at low cost.

Here, in the orientation control region, a plurality of magnets having magnetization directions different from each other along the thickness direction may be superimposed.

By forming the orientation control region by stacking magnets with different orientations along the thickness direction as described above, the orientation in the orientation control region can be controlled more finely.

Further, in the above permanent magnet, the plurality of magnets are two plate-shaped magnets, and the two plate-shaped magnets are stacked in the thickness direction in the orientation control region. can be done.

As described above, by stacking two plate-like magnets in the thickness direction to form an orientation control region, a permanent magnet capable of controlling magnetic flux can be manufactured at a lower cost.

Moreover, it can be set as the aspect whose external shape is a rectangular parallelepiped shape.

As described above, by forming the outer shape of the permanent magnet into a rectangular parallelepiped shape, it is possible to easily attach the permanent magnet to a rectangular parallelepiped magnet insertion hole provided in a conventional general magnet-embedded motor.

Further, in the above motor, the plurality of magnet insertion holes are arranged periodically around the rotation axis of the rotor and are accommodated in two continuous magnet insertion holes out of the plurality of magnet insertion holes. The two permanent magnets constitute the magnetic poles of the rotor, the two permanent magnets constituting the magnetic poles are arranged symmetrically with respect to the imaginary line, and each of the two permanent magnets It is also possible to adopt a mode in which the orientation control region is provided on the end side farther from the .

As described above, the two permanent magnets forming the same magnetic pole are arranged symmetrically with respect to the imaginary line, and each of the two permanent magnets has an orientation control region on the end side farther from the imaginary line. As a result, the magnetic flux controlled by the orientation control region is concentrated along the virtual line, increasing the magnetic flux density. As a result, the magnet torque in the motor is increased and the output torque is increased.

According to the present invention, a permanent magnet which can be manufactured at low cost and whose magnetic flux can be controlled, and a motor to which this permanent magnet is applied are provided.

1 is a schematic plan view of a motor according to one embodiment of the present invention; FIG. It is a schematic perspective view explaining the structure of a permanent magnet. It is the figure which expanded a part of FIG. It is a figure which shows the example of a change of the shape of a permanent magnet, and a combination of a magnet. It is a figure which shows the example of a change of the shape of a permanent magnet, and a combination of a magnet. FIG. 5 is a diagram showing a modification of the arrangement of permanent magnets in the core of the rotor; FIG. 4 is a diagram schematically showing the shape of a permanent magnet and a combination of magnets in Example 1; FIG. 10 is a diagram schematically showing the shape of a permanent magnet and a combination of magnets in Example 2; 4 is a diagram schematically showing the shape of a permanent magnet and the combination of magnets in Comparative Example 1. FIG. FIG. 10 is a diagram schematically showing the shape of a permanent magnet and a combination of magnets in Example 3; 7 is a diagram schematically showing the shape of a permanent magnet and the combination of magnets in Comparative Example 2. FIG.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and overlapping descriptions are omitted. Moreover, the present invention is not limited to the following embodiments, and various modifications are possible.

First, the configuration of the motor 1 according to the embodiment will be described with reference to FIG.

As shown in FIG. 1, a motor 1 includes a stator 2, a rotor 3 rotatably arranged inside the stator 2, and a shaft 8 connected to a core 7 of the rotor 3. is configured with The motor 1 is a so-called magnet-embedded motor (IPM motor) in which permanent magnets 4 are embedded inside a rotor 3 .

The stator 2 is composed of an iron core 5 and a plurality of windings 6 wound around the iron core 5 . A predetermined number of windings 6 are arranged at regular intervals on the inner peripheral surface of the stator 2 , and energization of the windings 6 generates a rotating magnetic field for rotating the rotor 3 .

The rotor 3 includes a core 7, a plurality of magnet insertion holes (not shown) provided in the core 7, and a plurality of permanent magnets 4 housed and fixed in the magnet insertion holes.

The core 7 is made of a laminated body such as thin electromagnetic steel sheets. A shaft hole is formed in the central portion of the core 7, and a shaft 8 serving as a rotating shaft of the rotor 3 is fitted in this shaft hole. A plurality of pairs (four pairs in FIG. 1) of magnet insertion holes are periodically arranged around the axis of the core 7 (corresponding to the rotation axis of the rotor 3). Each pair of magnet insertion holes is arranged symmetrically with respect to a virtual line extending from the axis of the core 7 (virtual line A shown in FIG. 3). Two permanent magnets 4 housed in two (a pair of) magnet insertion holes arranged symmetrically with respect to the imaginary line A are arranged so that the outer side of the core 7 has the same pole, so that one pole constitutes In the motor 1 shown in FIG. 1, the rotor 3 has four poles.

A permanent magnet 4 shown in FIG. 2 is accommodated in the magnet insertion hole. In this embodiment, the shape of the magnet insertion hole corresponds to the shape of the magnet to be inserted, and is substantially L-shaped. A space serving as a flux barrier may be formed in the magnet insertion hole. For the sake of explanation, FIG. 2 shows an XYZ orthogonal coordinate system.

FIG. 2A is a perspective view illustrating the permanent magnet 4, and FIG. 2B is a cross-sectional view of the permanent magnet 4 along the XY plane. As shown in FIGS. 2(A) and 2(B), the permanent magnets 4 are arranged in a direction orthogonal to the rotation axis direction of the rotor 3 (that is, in the extension of the main surface of the core 7 constituting the rotor 3). It is composed of two plate-shaped magnets 4A and 4B that are stacked along the existing direction). More specifically, the magnets 4A and 4B are rectangular flat plates. The “plate-like” magnets in this embodiment are magnets whose principal surfaces are arranged to face each other and are substantially parallel to each other. Therefore, for example, a "plate-shaped" magnet also includes a magnet having substantially parallel principal surfaces with inclined side surfaces or rounded corners of the principal surfaces.

The two magnets 4A, 4B can be permanent magnets made of the same material. The magnets 4A and 4B according to the present embodiment are composed of rare earth permanent magnets (rare earth magnets), and may be RTB permanent magnets, for example. Among them, an RTB system sintered magnet can be used. RTB based sintered magnets have grains (crystal grains) composed of R ₂ T ₁₄ B crystals and grain boundaries.

R in the RTB based sintered magnet represents at least one rare earth element. Rare earth elements refer to Sc, Y and lanthanoid elements belonging to Group 3 of the long period periodic table. Lanthanide elements include, for example, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu and the like. T in the RTB system sintered magnet represents Fe, or Fe and Co. Furthermore, one or more selected from other transition metal elements may be included. B in the RTB based sintered magnet represents boron (B), or boron (B) and carbon (C).

The RTB-based sintered magnet according to this embodiment may contain Cu, Al, or the like. By adding these elements, it becomes possible to increase the coercive force, increase the corrosion resistance, or improve the temperature characteristics of the magnetic properties.

Furthermore, the RTB based sintered magnet according to this embodiment may contain Dy, Tb, or both as a heavy rare earth element. The heavy rare earth element may be contained in crystal grains and grain boundaries. When the heavy rare earth element is not substantially contained in the crystal grains, it is preferably contained in the grain boundaries. The concentration of the heavy rare earth element at grain boundaries is preferably higher than that in crystal grains. The RTB based sintered magnet according to the present embodiment may be an RTB based sintered magnet in which a heavy rare earth element is grain boundary diffused. R-T-B system sintered magnets in which heavy rare earth elements are grain-boundary diffused can achieve residual magnetic flux density and coercive force with a smaller amount of heavy rare-earth elements than RTB system sintered magnets without grain-boundary diffusion. can be improved.

Further, when the magnets 4A and 4B according to the present embodiment are RTB system permanent magnets, the RTB system permanent magnets are manufactured by performing sintering as described above. It is not limited to -B system sintered magnets. For example, it may be an RTB permanent magnet manufactured by hot forming and hot working instead of sintering.

When the cold compact obtained by compacting the raw material powder at room temperature is subjected to hot compaction in which pressure is applied while being heated, the pores remaining in the cold compact disappear and are not sintered. It can be densified. Furthermore, by subjecting the molded body obtained by hot molding to hot extrusion as hot working, an RTB permanent magnet having a desired shape and magnetic anisotropy is obtained. can be obtained.

The magnets 4A and 4B may be magnets made of different materials.

The permanent magnet 4 is formed by overlapping (laminating) the magnet 4A and the magnet 4B in the thickness direction (height direction: Y-axis direction). The size of the permanent magnet 4 is appropriately selected depending on the outer diameter of the rotor, the number of poles, and the like. The magnet 4A has, for example, a long side length (length in the X-axis direction) in the range of 3 mm to 70 mm and a height (length in the Y-axis direction) in the range of 1 mm to 40 mm. Further, the magnet 4B has, for example, a long side length in the range of 1 mm to 35 mm and a height in the range of 1 mm to 40 mm. The long side length of the magnet 4B is preferably 5% or more and 50% or less, more preferably 10% or more and 40% or less, of the long side length of the magnet 4A. Moreover, the height of the magnet 4B is preferably 10% or more and 150% or less, more preferably 20% or more and 100% or less, with respect to the height of the magnet 4A.

It is preferable that the short sides of the magnets 4A and 4B have the same length, and as shown in FIG. It is preferred that the edges of the sides parallel to the plane coincide.

Moreover, the magnet 4B is laminated so that the short sides on one side of the magnet 4A overlap each other in plan view. In this embodiment, one short side 41A (the short side on the negative side of the X axis) included in the principal surface 40A (the surface parallel to the XZ plane) of the magnet 4A and the principal surface 40B of the magnet 4B (parallel to the XZ plane) The magnet 4B is laminated on the magnet 4A in a state in which the main surface 40A and the main surface 40B face each other in a state in which one short side 41B (the short side on the negative side of the X-axis) overlaps. As a result, when the permanent magnet 4 is viewed along the long side direction (X-axis direction) of the permanent magnet 4, one side (X-axis negative side where the magnets 4A and 4B are laminated) has a The thickness (height along the stacking direction) is large, and the thickness of the permanent magnet 4 is small on the other side (X-axis positive side where the magnet 4B is not stacked on the magnet 4A). Thus, the permanent magnet 4 according to this embodiment has regions where the thickness of the permanent magnet 4 is different from each other. In addition, the permanent magnet 4 has a substantially L-shaped cross section (surface parallel to the XY plane).

In the permanent magnets according to this embodiment, the magnets 4A and 4B are magnetized in different directions. Specifically, as shown in FIG. 2B, the magnet 4A is magnetized in a direction M1 (Y-axis positive direction) parallel to the height (thickness) direction. On the other hand, the magnet 4B is magnetized in a direction M2 inclined by a predetermined angle with respect to the magnetization direction M1 of the magnet 4A. It is assumed that the magnets 4A and 4B are uniformly oriented parallel to one axis.

In the region where the magnets 4B are stacked, when viewed in the height (thickness) direction of the permanent magnets 4, two magnets having magnetization directions different from each other are stacked. As a result, the magnetization direction in the area where the two magnets are superimposed will be different from the other areas. A region having a magnetization direction different from that of other regions is defined as an orientation control region 45 . In the permanent magnet 4, the orientation control region 45 is formed by stacking two types of magnets having different magnetization directions. That is, in the case of the permanent magnet 4, the orientation control region 45 is the region where the magnets 4B are superimposed.

In this embodiment, the magnetization direction M2 of the magnet 4B is inclined along the long side direction of the magnets 4A and 4B toward the end portion of the magnet 4A where the magnet 4B is not laminated (positive direction of the X axis). . Therefore, the flux (magnetic flux) from the permanent magnet 4 is in a state of being biased toward the region where the magnet 4A is not laminated from the upper surface of the permanent magnet 4 (the surface on the Y-axis positive side). That is, the magnetic flux density is increased.

By making the magnetization direction M1 and the magnetization direction M2 of the permanent magnet 4 different from each other, the direction and density of the flux (magnetic flux) of the permanent magnet 4 as a whole can be controlled. Moreover, by mounting the permanent magnet 4 on the rotor 3 of the motor 1 in a predetermined direction, the torque generated by the permanent magnet 4 in the motor 1 can be increased. This point will be described later.

The angle formed by the magnetization direction M1 and the magnetization direction M2 can be changed as appropriate, and can be, for example, about 1° to 45°. Also, like the magnet 4B, the method of varying the magnetization direction M2 from the height (thickness) direction is not particularly limited.

The magnets 4A and 4B may be joined with an adhesive or the like. A bonding layer may be interposed between the magnets 4A and 4B. When a bonding layer is interposed between the pair of magnets 4A and 4B, the distance between the magnets 4A and 4B is preferably in the range of 0.01 mm to 0.1 mm.

3 is a partially enlarged view of FIG. 1. FIG. The permanent magnets 4 are accommodated in magnet insertion holes (not shown) provided in the core 7 of the rotor 3, and arranged as shown in FIG.

Each pair of permanent magnets 4 is arranged symmetrically with respect to an imaginary line A extending from the axis of core 7 . More specifically, the permanent magnet 4 has a predetermined angle (for example, 45°) formed by a straight line extending from the long side of the substantially L shape (the long side formed by the magnet 4A) and the imaginary line A. 85°, but not limited to), and are arranged symmetrically. Thus, the permanent magnet 4 is housed in the magnet insertion hole so that the upper side (Y-axis positive side) in FIG. 2 faces the outer peripheral side of the core 7 . Further, when the permanent magnet 4 is housed in the magnet insertion hole, the cross section of the permanent magnet 4 perpendicular to the rotation axis of the rotor 3 (core 7) is a cross section parallel to the XY plane of the permanent magnet 4 in FIG.

As a result, as shown in FIG. 3 , the pair of permanent magnets 4 has a thickness of the permanent magnets 4 (extension of the shaft 8 The thickness of the permanent magnet 4 in the stacking direction when viewed from the direction, or the width of the permanent magnet 4 when viewed along the extending direction of the long side of the permanent magnet 4 on the main surface of the core 7) is large. , and the thickness of the permanent magnet 4 is small at both ends on the side closer to the virtual line A (the side closer to the rotation axis of the rotor 3).

Magnets 4B are stacked on both ends of the pair of permanent magnets 4 housed in the pair of magnet insertion holes on the far side from the virtual line A, respectively. As described above, the magnetization direction M2 of the magnet 4B is biased toward the side of the permanent magnet 4 where the magnet 4B is not laminated (the side where the upper surface of the magnet 4A is exposed). Therefore, the flux from the permanent magnet 4 is biased toward the side of the permanent magnet 4 where the magnet 4B is not laminated (the side where the upper surface of the magnet 4A is exposed), and the magnetic flux density is increased. As a result, the flux is concentrated along the imaginary line A above the permanent magnet 4 (on the outer side with respect to the rotating shaft of the rotor 3, that is, on the stator 2 side).

As for the lamination of the permanent magnets 4, a method is used in which the magnets 4A and 4B, which have already been separated into individual pieces with the above dimensions, are superimposed. If necessary, the magnets 4A and 4B may be chamfered by subjecting them to a predetermined polishing process (for example, barrel polishing).

Note that the permanent magnets 4 may be fixed in the magnet insertion holes by filling the magnet insertion holes with a filler as appropriate. A thermosetting resin, such as an epoxy resin or a silicone resin, can be used as the filler. However, if the permanent magnets 4 housed in the magnet insertion holes are fixed to the magnet insertion holes, it is not always necessary to use the filler.

Here, the permanent magnet 4 according to this embodiment has an orientation control region in which regions having magnetization directions different from each other are laminated in the height (thickness) direction. By having such a configuration, it is possible to realize magnetic flux control at low cost in the permanent magnets applied to the magnet-embedded motor.

A magnet-embedded motor is generally required to have high motor efficiency, and in many cases high output torque is also required. In such a case, rare earth magnets, which have higher magnetic performance than ferrite magnets, may be used as the embedded magnets. As described above, the vertical magnetic field forming method is often used for the production of ferrite magnets, which makes it possible to easily produce segmented magnets. Therefore, there is no method for precisely controlling the magnetization direction at low cost, and sufficient studies have not been made on improving the torque using the magnetization direction of the magnet.

On the other hand, according to the permanent magnet 4 according to the present embodiment, since it has the orientation control region 45, it is possible to control the magnetic flux density using the control of the magnetization direction. Therefore, in the magnet-embedded motor using the permanent magnet 4, the orientation control region 45 of the permanent magnet 4 can be used to control the magnetic flux density of the flux. etc., can be easily adjusted. In addition, in this permanent magnet 4, the orientation control region 45 is formed by combining pieces of the magnets 4A and 4B having different orientations from each other. A permanent magnet 4 whose magnetic flux density can be controlled can be obtained. As described above, the magnets 4A and 4B are uniformly oriented magnets parallel to one axis, and therefore can be manufactured by a general manufacturing method. Therefore, the manufacturing cost of the magnet can be greatly reduced with respect to orientation control.

In addition, in the motor 1 including the rotor 3 (core 7) in which the permanent magnets 4 according to the present embodiment are accommodated in a pair of magnet insertion holes forming one magnetic pole, the permanent magnets 4 above (the rotor 3, the flux is concentrated along the virtual line A on the stator 2 side. By increasing the density of the flux (magnetic flux density) directed toward the stator 2 in this way, the magnet torque in the motor 1 is increased. Therefore, the effect that the output torque of the motor 1 is increased can be obtained.

The orientation control region 45 is formed only partially along the longitudinal direction (X-axis direction) of the permanent magnet 4 . If the orientation control region 45 is formed over the entire permanent magnet 4, it is possible to control the direction of the flux from the permanent magnet 4, but the control of the magnetic flux density is insufficient. Therefore, the orientation control region 45 is provided in a partial region along the longitudinal direction of the permanent magnet 4 .

Further, the permanent magnet 4 is configured by combining a plurality of plate-shaped magnets 4A and 4B. Since the plate-shaped magnets 4A and 4B can be manufactured by a general manufacturing method, it is possible to suppress an increase in cost associated with shape processing and the like.

Specifically, the permanent magnet 4 according to the present embodiment has a region on one end side that is thicker than other regions. In the case of the permanent magnet 4, the area where the magnet 4B is overlapped on one end side is thicker than the other area (area where the magnet 4B is not overlapped). More specifically, in a cross section orthogonal to the rotation axis of rotor 3 (a cross section parallel to the main surface of core 7), one end side is thicker than the other end side. By having such a configuration, it is possible to suppress demagnetization in a region that is likely to be demagnetized.

In general, it is known that in a motor to which permanent magnets are attached, a magnetic field (opposite magnetic field) is applied in a direction opposite to the magnetization direction of partial magnets as the rotor rotates. The area where the reverse magnetic field is applied varies depending on the arrangement of the permanent magnets, etc., but it is known that the reverse magnetic field is applied to the end of the rotor on the rear side with respect to the rotation direction (the side opposite to the rotation direction), for example. . For example, if the arrow R shown in FIG. 3 is the direction of rotation of the rotor 3, it is considered that a reverse magnetic field is applied near the right end of the right permanent magnet 4 of the two permanent magnets 4 shown in FIG. . Thus, there is concern that the permanent magnet may be demagnetized in the region where the opposite magnetic field is generated. Conventionally, however, demagnetization has been generally prevented by increasing the coercive force of the material, such as by including a heavy rare earth element in the magnet material. However, heavy rare earth elements are expensive and increase the material cost of the magnet. In view of this point, for example, the use of diffusion by heat treatment to contain the heavy rare earth element only in a part of the region is also being studied, but the material cost for containing the heavy rare earth element is still high. In addition, since heat treatment is required, it cannot be said that the manufacturing cost of the permanent magnet can be sufficiently suppressed.

On the other hand, in the permanent magnet 4 according to this embodiment, the one end side where the magnet 4B is superimposed is thicker than the other regions. That is, the permeance coefficient of the permanent magnets 4 can be adjusted by forming a region where the permanent magnets 4 have a large thickness in the cross section orthogonal to the rotation axis of the rotor 3 on one end side. The permeance coefficient is the thickness of the magnet in the direction of magnetization and the width of the magnet in the direction perpendicular to the magnetization direction of the magnet (in FIG. 2, the length in the X-axis direction when the magnetization direction is the Y-axis direction). , varies depending on the ratio of . Also, a region of a magnet with a small permeance coefficient is likely to be demagnetized due to the influence of a reverse magnetic field or the like. Therefore, in the permanent magnet 4, by providing a region with a large thickness at one end of the permanent magnet 4 that is likely to receive the opposite magnetic field, when the permanent magnet 4 is attached to the rotor 3, Local demagnetization that can occur during rotation of 3 can be suppressed. That is, by arranging a thicker region of the permanent magnets 4 in a region where a reverse magnetic field is likely to be applied, demagnetization in that region can be suppressed.

Further, the permanent magnet 4 is configured by combining a plurality of plate-like magnets 4A and 4B. Attempting to manufacture a magnet shaped like the permanent magnet 4 increases the manufacturing cost. On the other hand, the plate-shaped magnets 4A and 4B can be manufactured by a general manufacturing method, so that an increase in cost can be suppressed. Also, in the permanent magnet 4, local demagnetization can be suppressed by combining a plurality of magnets 4A and 4B and changing the thickness thereof. In this way, instead of changing the material, the permanent magnet 4 having regions with different thicknesses in the cross section orthogonal to the rotation axis of the rotor 3 by combining a plurality of plate-shaped magnets 4A and 4B , can be manufactured at low cost and can suppress local demagnetization during rotation of the rotor.

It should be noted that forming a region where the thickness of the permanent magnets 4 in the cross section orthogonal to the rotation axis of the rotor 3 is large on "one end side" means that It means that the area where the thickness of the permanent magnet 4 is thicker in the orthogonal cross section is provided at the end rather than near the center of the permanent magnet 4 . In the permanent magnet of this embodiment, a thick region is formed at one end and a region where the magnet 4B extends from the end. It need not be provided including the ends. For example, the corners of the permanent magnet 4 may be rounded to make the area inside the end portion "a thicker area".

FIG. 4 is a modification of the combination of two magnets in the permanent magnet. FIGS. 4A and 4B both show cross-sectional views of permanent magnets according to modifications (cross-sectional views in a cross section perpendicular to the rotating shaft of the rotor).

The permanent magnet 51 shown in FIG. 4A is the same as the permanent magnet 4 in that two magnets 4C and 4D are stacked in the thickness direction, but the permanent magnet 51 as a whole has a rectangular parallelepiped shape. It is That is, the magnet 4C has a rectangular parallelepiped shape corresponding to the permanent magnet 51, and a space portion for arranging the magnet 4D is cut out. By arranging magnets 4D having different orientations in the cutout space, permanent magnets 51 having orientation control regions 45 are formed. Even with such a shape, magnetic flux control by the permanent magnet 51 can be realized at low cost. Thus, the shape of the permanent magnet according to this embodiment can be changed as appropriate.

Further, a conventional magnet-embedded motor generally uses a rectangular parallelepiped permanent magnet such as the permanent magnet 51 . Therefore, when the permanent magnet 51 has a rectangular parallelepiped shape, it can be easily attached to a magnet insertion hole provided in a conventional magnet-embedded motor. That is, the permanent magnet 51 can be easily applied to a conventional magnet-embedded motor.

Similar to the permanent magnet 4, the permanent magnet 52 shown in FIG. 4B has a magnet 4D with a different orientation overlaid on a flat plate-like magnet 4C. However, in the permanent magnet 52, two magnets 4D are stacked on both ends in the longitudinal direction (X-axis direction) of the magnet 4C, and two orientation control regions 45 are formed. The orientations of the magnets 4D provided in the two orientation control regions 45 are both inclined near the center in the longitudinal direction of the magnets 4C. Therefore, the flux from the permanent magnet 52 is concentrated above the center of the magnet 4C in the longitudinal direction. That is, a region with a high magnetic flux density is formed above the vicinity of the center in the longitudinal direction of the magnet 4C. Thus, the number and arrangement of the orientation control regions 45 can be changed as appropriate. Also, by changing the arrangement of the orientation control regions 45, it is possible to control the region where the magnetic flux density concentrates. The area where the magnetic flux density concentrates can be appropriately designed according to the shape and performance of the magnet-embedded motor to which the permanent magnet 52 is attached.

As shown in FIG. 4, the number of magnets used for the permanent magnets can be changed as appropriate. Also, the method of combining the magnets can be changed as appropriate.

FIG. 5 is another modification of the combination of two magnets in the permanent magnet. FIGS. 5A to 5C are cross-sectional views of permanent magnets according to modifications (cross-sectional views perpendicular to the rotation axis of the rotor). In FIGS. 5A to 5C, two magnets 4C and 4D having different thicknesses and different orientations are combined to form a permanent magnet.

The permanent magnet 53 shown in FIG. 5A is formed by stacking the two magnets 4A and 4B in the thickness direction as described in the above embodiment, instead of forming a region with a large thickness. By arranging magnets 4C and 4D that are different from each other and have different orientations from each other and arranging them along the long side direction (X-axis direction) of the permanent magnet 4, a region with a large thickness is formed. Since the orientation of the magnet 4D is tilted compared to the magnet 4C, the orientation control region 45 is the region where the magnet 4D is arranged. The orientation control region 45 in the permanent magnet 53 is not a region formed by overlapping two types of magnets having different magnetization directions like the permanent magnet 4, but a region formed by one magnet. In this manner, the number and combination of magnets forming the orientation control region 45 can be changed as appropriate.

Also, the method of combining a plurality of magnets in the permanent magnet can be changed as appropriate. It should be noted that even when the magnet combination method is changed, the permanent magnet can be manufactured at low cost by combining plate-like magnets to form the permanent magnet. In addition, when forming a permanent magnet by arranging magnets along the long side direction (X-axis direction) of the permanent magnet 51, compared with the case where the magnets are laminated in the thickness direction (Y-axis direction), the It is conceivable that eddy current loss can be reduced.

The permanent magnet 54 shown in FIG. 5B is formed by combining magnets 4C and 4D having different thicknesses and different orientations and arranging them along the long side direction (X-axis direction) of the permanent magnet 4. It is the same as the permanent magnet 53 in that a region with a large thickness corresponding to the control region 45 is formed, but the surface on which the projecting region is formed is different. That is, the permanent magnet 53 is different from the permanent magnet 53 in that a part of the principal surface (the principal surface on the lower side in the drawing) that is arranged on the rotating shaft side when the permanent magnet 54 is accommodated in the magnet insertion hole protrudes. In this way, the arrangement of the projecting portions when forming regions with different thicknesses in the permanent magnet is not limited to the surface that is arranged outwardly with respect to the rotating shaft when accommodated in the magnet insertion hole.

A permanent magnet 55 shown in FIG. 5(C) is different from other permanent magnets in that a portion of both main surfaces of the permanent magnet is formed with an area projecting compared to other areas. As shown in FIG. 5(C), the permanent magnet 55 has regions that protrude in comparison with other regions on a part of both opposing principal surfaces, and this region serves as the orientation control region 45. Equivalent to. In this way, when a region projecting more than other regions is formed on a part of both of the opposing main surfaces, the permanent magnet 55 has a cross-sectional (surface parallel to the XY plane) shape of approximately T. It has a character shape. As described above, even if the cross-sectional shape of the permanent magnet 55 is substantially T-shaped instead of substantially L-shaped, the formation of the thick region allows the permeance coefficient in the region to be increased. Therefore, local demagnetization during rotation of the rotor can be suppressed in the same manner as the permanent magnets 4 and the like.

The method of combining magnets when forming the permanent magnet 54 shown in FIG. 5(B) and the permanent magnet 55 shown in FIG. 5(C) can also be changed as appropriate. For example, three magnets may be combined to form a permanent magnet.

FIG. 6 shows a modification of the arrangement of permanent magnets housed in the core 7 of the rotor 3 in the motor 1. FIG. As shown in FIGS. 1 and 3, in the above embodiment, one magnetic pole and two permanent magnets 4 in the rotor 3 are arranged symmetrically with respect to the virtual line A. A combination of permanent magnets 4 and permanent magnets of other shapes may be used to form one magnetic pole in rotor 3 . It should be noted that illustration of the magnet insertion hole is omitted in FIG.

FIG. 6 shows an example in which the permanent magnets 4 described in the above embodiment are arranged as a pair of permanent magnets, and a plate-shaped magnet 4E different from the magnets 4A and 4B is arranged between them. . In this example, three permanent magnets arranged in succession constitute the magnetic pole. Thus, the number and arrangement of permanent magnets forming one magnetic pole in the rotor 3 can be changed as appropriate.

In the example shown in FIG. 6, orientation control regions 45 are provided at both ends of three continuously arranged permanent magnets that constitute the magnetic pole. Therefore, the magnetic fluxes from these three permanent magnets are concentrated above the magnet 4C (outside the rotor 3). Therefore, the flux density in the direction of the stator 2 can be preferably increased.

However, depending on the design of the magnet-embedded motor, it may be preferable to disperse the flux of the permanent magnets forming the magnetic poles to some extent. In such a case, it is possible to appropriately change the arrangement of the orientation control regions in the permanent magnets attached to the magnet-embedded motor. For example, the orientation control region may be arranged on the central side of the plurality of permanent magnets forming the magnetic poles.

As described above, according to the permanent magnet 4 according to the present embodiment and the motor 1 to which the permanent magnet 4 is attached, the orientation control region 45 having the magnetization direction different from that of the other regions is provided, so that the permanent magnet 4 is attached to the rotor 3 . It is possible to control the magnetic flux of the permanent magnet that is applied. Also, the permanent magnet 4 is configured by combining a plurality of magnets 4A and 4B with mutually different orientations. Therefore, the control of the magnetic flux in the permanent magnet can be realized at low cost.

Further, when the orientation control region 45 is formed by stacking magnets with different orientations along the thickness direction, the orientation in the orientation control region 45 can be controlled more finely.

Moreover, by laminating two plate-shaped magnets 4A and 4B in the thickness direction to form the orientation control region 45, the permanent magnet 4 capable of controlling the magnetic flux can be manufactured at a lower cost.

Further, when the outer shape of the permanent magnet is a rectangular parallelepiped, it can be easily attached to a rectangular parallelepiped magnet insertion hole provided in a conventional general magnet-embedded motor.

Furthermore, the two permanent magnets 4 that form the same magnetic pole in the motor 1 are arranged symmetrically with respect to the virtual line A, and each of the two permanent magnets 4 is positioned at the end farther from the virtual line A for orientation control. With the configuration having the region 45, the magnetic flux controlled by the orientation control region 45 is concentrated along the imaginary line A, and the magnetic flux density is increased. As a result, the magnet torque in the motor 1 is increased, and the output torque is increased.

The present invention is not limited to the above embodiments, and various modifications are possible without departing from the scope of the invention.

For example, the number of magnet insertion holes provided in the motor can be increased or decreased as appropriate, and the positional relationship between the magnet insertion holes can also be changed as appropriate. Also, the number of magnets constituting the permanent magnet can be changed as appropriate. Moreover, the shape can also be changed suitably.

Also, the permanent magnet according to the present embodiment can be applied to motors other than the magnet-embedded motor.

The contents (effects, etc.) of the present invention will be described in more detail with reference to examples and comparative examples, but the present invention is not limited to the following examples.

(Example 1)
The output torque of the motor 1 when the permanent magnet 4 was incorporated in the rotor 3 of the motor 1 was obtained using the finite element method. A motor 1 includes a stator 2 having 24 slots (not shown), and a winding 6 is wound 30 turns in a concentrated manner through each of the 24 slots. The windings 6 are electrically connected in a predetermined order, connected to a three-phase AC power supply (not shown), and configured to generate a rotating magnetic field for rotating the rotor 3 . The motor 1 has a pair of permanent magnets 4 as shown in FIG. Thus, the motor 1 is an inner rotor type IPM motor with 16 poles and 24 slots.

Magnetic properties of the magnets 4A and 4B (see FIG. 7) forming the permanent magnet 4 are such that the residual magnetic flux density Br is 1.35 [T] and the coercive force Hcj is 1500 [kA/m] at 20°C. The residual magnetic flux density Br is 1.1745 [T], and the coercive force Hcj is 570 [kA/m]. The magnet 4A forming the permanent magnet 4 has a long side length of 11.6 mm and a height of 5 mm. The long side length of the magnet 4B forming the permanent magnet 4 is 2.5 mm, which is 22% of the long side length of the magnet 4A. Similarly, the height of the magnet 4B forming the permanent magnet 4 is 2 mm, which is 40% of the height of the magnet 4A.

As shown in FIG. 7, the magnetization direction M1 of the magnet 4A is the positive Y-axis direction. The magnetization direction M2 of the magnet 4B is inclined by 30° (30° from the Y-axis positive direction) toward the end portion of the magnet 4A where the magnet 4B is not laminated along the long side direction of the magnets 4A and 4B. there is Therefore, the flux (magnetic flux) from the permanent magnet 4 is in a state where it is biased from the upper surface of the permanent magnet 4 (the surface on the Y-axis positive side) toward the area where the magnet 4A is not laminated. In Example 1 configured as described above, the rotor 3 is rotated at 1000 [rpm] while a three-phase alternating current with a peak current of 100 [A] and a current phase angle of β = 30° is applied to the winding 6 at 20 ° C. The output torque of the motor 1 was obtained by the finite element method.

(Example 2)
Example 2 has the same configuration as Example 1 except that the permanent magnets 4 in Example 1 are replaced with permanent magnets 53 shown in FIGS. 8 and 5A. Note that FIG. 5A is a schematic diagram showing the positional relationship and magnetization directions of two magnets, and the dimensions of the magnets are more accurate in FIG. 8 than in FIG. 5A. In the permanent magnet 53, instead of stacking the two magnets 4A and 4B in the thickness direction like the permanent magnet 4 of the first embodiment, two magnets 4C and 4D having different thicknesses are arranged in the long side direction (X-axis direction). direction) to form regions of greater thickness. Magnet 4D is thicker than magnet 4C. In the permanent magnet 53, the protruding portion forming the thicker region is arranged on the surface that is arranged outwardly with respect to the rotating shaft when the permanent magnet 53 is accommodated in the magnet insertion hole. Magnets 4C and 4D are oriented differently from each other. As shown in FIG. 8, the magnetization direction M3 of the magnet 4C is the Y-axis positive direction. The magnetization direction M4 of the magnet 4D is inclined by 30° toward the magnet 4C (30° from the positive direction of the Y-axis). In Example 2 configured as described above, similarly to Example 1, 1000[A] of 1000[A] of 3-phase AC current with a current phase angle of β=30° at 20° C. rpm], the output torque of the motor 1 was obtained by the finite element method.

(Comparative example 1)
Comparative Example 1 has the same configuration as Example 1 except that the permanent magnet 4 in Example 1 is replaced with a permanent magnet 401 shown in FIG. The permanent magnet 401 is formed by stacking a magnet 4A (similar to the magnet 4A of the permanent magnet 4) and a magnet 401B in the thickness direction. That is, the permanent magnet 401 employs a magnet 401B instead of the magnet 4B of the permanent magnet 4 of the first embodiment. The magnetization direction M2 of the magnet 4B of the permanent magnet 4 is inclined by 30° from the positive direction of the Y-axis, while the magnetization direction M5 of the magnet 401B of the permanent magnet 401 is the positive direction of the Y-axis. In Comparative Example 1 configured as described above, similarly to Example 1, a three-phase alternating current of 20° C., a peak current of 100 [A], and a current phase angle of β=30° was applied to the winding 6 while passing 1000 [A]. rpm], the output torque of the motor 1 was obtained by the finite element method.

(Comparison result)
As shown in Table 1 showing the comparison results, when the value of the output torque of Comparative Example 1 is taken as 100%, the torque ratio of Example 1 is 101.2%, and the torque ratio of Example 2 is 102.3. %Met.

(Example 3)
Example 3 has the same configuration as Example 1 except that the permanent magnets 4 in Example 1 are replaced with permanent magnets 55 shown in FIGS. 10 and 5C. Note that FIG. 5C is a schematic diagram showing the positional relationship and magnetization direction of the two magnets, and the dimensions of the magnets are more accurate in FIG. 10 than in FIG. 5C. More specifically, in the permanent magnet 55 of Example 3, two magnets 4C and 4D are arranged side by side along the long side direction (X-axis direction) in the same manner as the permanent magnet 53 of Example 2. , the magnetization direction M3 of the magnet 4C is the positive direction of the Y-axis, and the magnetization direction M4 of the magnet 4D is inclined by 30° toward the magnet 4C (30° from the positive direction of the Y-axis). In the permanent magnet 53 of Example 2, the projecting portion forming the region with a large thickness is arranged only outwardly with respect to the rotation axis, whereas in the permanent magnet 55 of Example 3, the projecting portion is It is formed on both opposing main surfaces. In Example 3 configured as described above, similarly to Example 1, a three-phase alternating current of 20° C., a peak current of 100 [A], and a current phase angle of β=30° is applied to the winding 6 while passing 1000 [A]. rpm], the output torque of the motor 1 was obtained by the finite element method.

(Comparative example 2)
Comparative Example 2 has the same configuration as Example 3 except that the permanent magnets 55 in Example 3 are replaced with permanent magnets 402 shown in FIG. The permanent magnet 402 is formed by arranging a magnet 4C (similar to the magnet 4C of the permanent magnet 55) and a magnet 402D side by side along the long side direction. That is, the permanent magnet 402 employs a magnet 402D instead of the magnet 4D of the permanent magnet 55 of the third embodiment. The magnetization direction M4 of the magnet 4D of the permanent magnet 55 is inclined by 30° from the positive direction of the Y-axis, while the magnetization direction M6 of the magnet 402D of the permanent magnet 402 is the positive direction of the Y-axis. In Comparative Example 2 configured as described above, similarly to Example 1, a three-phase alternating current of 20° C., a peak current of 100 [A], and a current phase angle of β=30° was applied to the winding 6 while passing 1000 [A]. rpm], the output torque of the motor 1 was obtained by the finite element method.

(Comparison result)
As shown in Table 1 showing the comparison results, the torque ratio of Example 3 was 100.6% when the value of the output torque of Comparative Example 2 was taken as 100%.

As described above, it was confirmed that the torque ratios of Examples 1 to 3 were all higher than the torque ratio of Comparative Example 1 or Comparative Example 2, which was 100%. That is, it was shown that the effect of increasing the output torque of the motor 1 can be obtained by employing the configurations of Examples 1-3.

Reference Signs List 1 Motor 3 Rotor 4, 51, 52 Permanent magnet 7 Core 45 Orientation control region 4A, 4B, 4C Magnet.

Claims (11)

A permanent magnet made of a rare earth magnet attached to a rotor of a motor,
Constructed by combining only a plurality of rectangular plate-shaped magnets with magnetization directions different from each other,
Having an orientation control region whose magnetization direction is different from other regions along the longitudinal direction,
The permanent magnet, wherein the orientation control region has a protrusion. A permanent magnet made of a rare earth magnet attached to a rotor of a motor,
Composed by combining a plurality of magnets whose magnetization directions are different from each other and whose magnetization directions form an angle of 1° to 45°,
Having an orientation control region whose magnetization direction is different from other regions along the longitudinal direction,
The permanent magnet, wherein the orientation control region has a protrusion. 3. The permanent magnet according to claim 1 , wherein in said orientation control region, a plurality of magnets having magnetization directions different from each other along the thickness direction are stacked. 4. The permanent magnet according to claim 3, wherein said plurality of magnets are stacked on each other only along said thickness direction. The plurality of magnets are two plate-shaped magnets,
5. The permanent magnet according to claim 3 , wherein said two plate-like magnets are stacked in said thickness direction in said orientation control region. The permanent magnet according to any one of claims 1 to 4 , which has a rectangular parallelepiped outer shape. The permanent magnet according to any one of claims 1 to 5 , wherein the protrusion protrudes outward from the rotor. a rotor having a plurality of magnet insertion holes;
a plurality of permanent magnets made of rare earth magnets respectively accommodated in the plurality of magnet insertion holes;
A motor having
Some of the permanent magnets are formed by combining only a plurality of rectangular plate-like magnets with magnetization directions different from each other, and an orientation control region with a magnetization direction different from other regions is formed along the longitudinal direction. have
The motor, wherein the orientation control region has a protrusion. a rotor having a plurality of magnet insertion holes;
a plurality of permanent magnets made of rare earth magnets respectively accommodated in the plurality of magnet insertion holes;
a motor having
Some of the permanent magnets are formed by combining a plurality of magnets whose magnetization directions are different from each other and whose magnetization directions form an angle of 1° to 45°. has an orientation control region in which the direction of is different from that of other regions,
The motor, wherein the orientation control region has a protrusion. The plurality of magnet insertion holes are arranged periodically around the rotation axis of the rotor,
Magnetic poles of the rotor are formed by two permanent magnets accommodated in two continuous magnet insertion holes among the plurality of magnet insertion holes,
The two permanent magnets that make up the magnetic pole are arranged symmetrically with respect to a virtual line,
10. The motor according to claim 8 or 9 , wherein each of said two permanent magnets has said orientation control region on an end side farther from said imaginary line. 11. The motor according to any one of claims 8 to 10 , wherein the protrusion protrudes outward from the rotor.

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