JP7243117B2 - permanent magnets and motors - Google Patents

Description

The present invention relates to permanent magnets and motors.

In a magnet-embedded motor in which permanent magnets are embedded in a rotor, the permanent magnets may be demagnetized by a demagnetizing field generated when the rotor rotates. On the other hand, for example, in Patent Document 1, a heavy rare earth element is adhered to the surface of a magnet, and heat treatment is performed to diffuse the heavy rare earth element into the interior, thereby diffusing the heavy rare earth element in a part of the magnet. A technique for forming a magnet having regions with different coercive forces by forming regions is disclosed.

JP 2012-4147 A

However, in the technique described in Patent Document 1, the cost increases because the heavy rare earth element used to increase the coercive force of the magnet is basically expensive. In addition, work costs related to the diffusion of heavy rare earth elements such as heat treatment are also incurred.

The present invention has been made in view of the above, and provides a permanent magnet that can be manufactured at low cost and can suppress local demagnetization during rotor rotation, and a motor to which this permanent magnet is applied. intended to

In order to achieve the above object, a permanent magnet according to the present invention is a permanent magnet that is attached to a rotor of a motor, is composed of a combination of a plurality of plate-shaped magnets, and when attached to the rotor, rotates. In a cross section perpendicular to the axis of rotation of the child, one end has a thicker region than the other regions.

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 accommodated in the plurality of magnet insertion holes, wherein the permanent magnet part of which is formed by combining a plurality of plate-shaped magnets, and in a cross section orthogonal to the rotation axis of the rotor, a region having a thickness greater than that of the other regions on one end side have

According to the permanent magnet and the motor described above, the permeance coefficient of the permanent magnet can be adjusted by forming the thicker area of the permanent magnet on one end side. Therefore, if a region having a large thickness is provided on one end side of the permanent magnet, when this permanent magnet is attached to the rotor, local demagnetization that may occur during rotation of the rotor is suppressed. be able to. Further, the above permanent magnet is configured by combining a plurality of plate-shaped magnets. Therefore, a permanent magnet having a region with a large thickness can be manufactured at low cost, and an increase in cost can be suppressed.

Here, in the above permanent magnet, the plurality of magnets may be stacked in the thickness direction of the permanent magnet.

With such a configuration, the permanent magnet can be manufactured by combining magnets with a small thickness, and the amount of magnets used as the permanent magnet can be minimized, so that the cost can be suppressed. Permanent magnets can be manufactured.

Also, the plurality of magnets may be combined along the long side direction of the permanent magnet.

With such a configuration, magnets that are relatively easy to handle can be combined with each other, and an increase in assembly cost can be suppressed.

In addition, when the permanent magnet is attached to the rotor, a part of the main surface arranged on the outer side of the rotor protrudes, thereby forming the thick region. be able to.

Permanent magnets are susceptible to local demagnetization during rotation outside the rotor. Therefore, by adopting a configuration in which a part of the main surface on the outer side of the rotor protrudes, local demagnetization during rotation can be suitably suppressed.

Further, in the above motor, the plurality of magnet insertion holes are periodically arranged around the rotation axis of the rotor and are inserted into one or more continuous magnet insertion holes among the plurality of magnet insertion holes. The magnetic poles of the rotor are composed of the permanent magnets formed on the rotor. It is configured by combining a plurality of magnets, and in a cross section perpendicular to the rotation axis of the rotor, one end side may have a larger thickness than other regions.

Of the permanent magnets that are attached to the rotor and constitute the magnetic poles, the permanent magnets at the end on the rear side with respect to the rotation direction are susceptible to local demagnetization during rotation. Therefore, the permanent magnet at the end on the rear side with respect to the rotation direction is configured to have a region with a larger thickness than the other region on one end side, so that local demagnetization during rotation is suitable. can be suppressed to

Also, the plurality of magnet insertion holes are arranged periodically around the rotation axis of the rotor, and two permanent magnets are inserted into two continuous magnet insertion holes out of the plurality of magnet insertion holes. The magnetic poles of the rotor are formed by the two permanent magnets forming the magnetic poles, and the two permanent magnets forming the magnetic poles are arranged symmetrically with respect to a virtual line. In a cross section perpendicular to the rotation axis of the rotor, an end portion farther from the imaginary line has a region having a greater thickness than other regions.

As described above, each of the two permanent magnets arranged symmetrically with respect to the imaginary line and forming the same magnetic pole is positioned at the far end from the imaginary line in a cross section orthogonal to the rotation axis of the rotor. By having a region having a larger thickness than other regions on the side of the rotor, localized vibration during rotation that may occur at the end on the rear side with respect to the direction of rotation regardless of the direction of rotation of the rotor. demagnetization can be suitably suppressed.

ADVANTAGE OF THE INVENTION According to this invention, the permanent magnet which can be manufactured at low cost and can suppress the local demagnetization at the time of rotation of a rotor, and the 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. FIG. 5 is a diagram showing a modification of the arrangement of permanent magnets in the core of the rotor; (A) is a diagram for explaining the demagnetization rate of magnetization in Example 1, and (B) is a partially enlarged view of (A). (A) is a diagram for explaining the demagnetization rate of magnetization in Example 2, and (B) is a partially enlarged view of (A). (A) is a diagram for explaining the demagnetization rate of magnetization in Example 3, and (B) is a partially enlarged view of (A). (A) is a diagram for explaining the demagnetization rate of magnetization of Comparative Example 1, and (B) is a partially enlarged view of (A).

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. and 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 plurality of 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.

As shown in FIG. 2, the permanent magnets 4 are stacked in a direction perpendicular to the rotation axis direction of the rotor 3 (that is, the extending direction 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 connected to each other. 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, 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. When the RTB sintered magnets in which the heavy rare earth element is grain boundary diffused are used as the magnets 4A and 4B according to the present embodiment, the heavy rare earth element is not grain boundary diffused in a part of the magnet. , grain boundary diffused throughout the magnet can be used. With such a configuration, the productivity is improved and the cost is reduced.

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 stacking (stacking) the magnet 4A (positive side of the Y-axis) 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 preferable that the ends of the side surfaces parallel to the XY plane that face each other) coincide with each other.

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).

The magnets 4A and 4B are magnetized in the same direction, and in this embodiment, magnetized in a direction M (Y-axis positive direction) parallel to the height (thickness) direction. It is assumed that the magnets 4A and 4B are uniformly oriented parallel to one axis.

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 spacing 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).

The permanent magnet 4 can be fixed in the magnet insertion hole by appropriately filling the magnet insertion hole with a filler. Thermosetting resins such as epoxy resins and silicone resins can be used as fillers. 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.

As described above, the permanent magnet 4 according to this 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. On the other hand, conventionally, demagnetization is 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 considered, 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-shaped 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".

In addition, the permanent magnet 4 forms a region having a large thickness by stacking plate-like magnets 4A and 4B. Therefore, as shown in FIG. 2, the permanent magnet 4 has a main surface on the lower side (negative side of the Y-axis) formed by a main surface on the side opposite to one main surface 40A of the magnet 4A. It's becoming That is, when the permanent magnet 4 is accommodated in one of the magnet insertion holes, the main surface arranged on the rotating shaft side is a flat surface, and when the magnets 4B are overlapped and accommodated in the magnet insertion hole on the other side, the main surface rotates. A region with a large thickness is formed by protruding a portion of the main surface arranged on the outer side with respect to the axis. However, how to form the thick regions in the permanent magnet 4 can be changed as appropriate. Also, the combination of magnets forming the permanent magnet 4 can be changed as appropriate.

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

The permanent magnet 51 shown in FIG. 4A 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, which are different from each other, along the long side direction (X-axis direction) of the permanent magnet 4, a region having a large thickness is formed. In this way, the method of combining a plurality of magnets when forming a permanent magnet having a region with a greater thickness than other regions 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) like the permanent magnet 51, the magnet has a higher It is conceivable that the generated eddy current loss can be reduced.

A permanent magnet 52 shown in FIG. 4B is the same as the permanent magnets 4 and 51 in that a portion of the main surface on one side protrudes to form a region with a large thickness. The surface on which the area to be formed is different. That is, the permanent magnet 52 is different from the permanent magnet 51 in that a part of the main surface (the main surface on the lower side in the drawing) that is arranged on the rotating shaft side when the permanent magnet 52 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 53 shown in FIG. 4(C) is different from other permanent magnets in that a portion of both main surfaces of the permanent magnet is formed with an area that protrudes compared to other areas. As shown in FIG. 4(C), in the case where regions protruding in comparison with other regions are formed on part of both of the opposing main surfaces, the permanent magnet 53 has a cross section (parallel to the XY plane). The shape of the surface is approximately T-shaped. As described above, even if the cross-sectional shape of the permanent magnet 53 is substantially T-shaped instead of substantially L-shaped, the formation of the region with the large thickness 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 52 shown in FIG. 4B and the permanent magnet 53 shown in FIG. 4C can also be changed as appropriate. For example, three magnets may be combined to form a permanent magnet.

FIG. 5 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.

In FIG. 5A, the permanent magnet 4 having a large thickness region composed of magnets 4A and 4B is arranged as the permanent magnet on the right side of the drawing, which is the rear side in the direction of rotation of the rotor 3 indicated by the arrow R. However, only the magnet 4A is arranged as the permanent magnet on the left side in the drawing, which is the rear side with respect to the rotation direction of the rotor 3 indicated by the arrow R. In this manner, the arrangement of the permanent magnets can be appropriately changed in consideration of the area to which the opposite magnetic field is applied. At that time, the placement may not be symmetrical with respect to the virtual line.

In FIG. 5B, the permanent magnets 4 described in the above embodiment are arranged as a pair of permanent magnets, and a plate-like magnet 4E different from the magnets 4A and 4B is arranged between them. In the example shown in FIG. 5B, three permanent magnets arranged in succession constitute the magnetic pole. Thus, the number of permanent magnets forming one magnetic pole in the rotor 3 should be one or more, and the number and arrangement thereof can be changed as appropriate.

As described above, according to the permanent magnet 4 and the motor 1 to which the permanent magnet 4 is attached according to the present embodiment, the permanent magnet 4 can be A permeance factor of 4 can be adjusted. Therefore, if a region with a large thickness is provided on one end side of the permanent magnet 4, when this permanent magnet 4 is attached to the rotor 3, local attenuation that may occur when the rotor 3 rotates is minimized. Can suppress magnetism. Further, the permanent magnet 4 is constructed by combining a plurality of plate-shaped magnets 4A and 4B. Therefore, the permanent magnet 4 having a region with a large thickness can be manufactured at low cost, and an increase in cost can be suppressed.

Further, in the above permanent magnet, a plurality of magnets 4A and 4B are stacked in the thickness direction of the permanent magnet 4, so that the above permanent magnet can be manufactured by combining small-thickness magnets. Therefore, the permanent magnet can be manufactured while suppressing costs related to magnetization and the like.

Further, when the permanent magnets 4 are attached to the rotor 3, a portion of the main surface arranged on the outer side of the rotor 3 protrudes, thereby forming a thick region. , the effect of local demagnetization during rotation can be suitably suppressed outside the rotor.

In addition, among the permanent magnets attached to the rotor 3 of the motor 1 to form the magnetic poles, the permanent magnets 4 at the ends on the rear side with respect to the rotation direction are susceptible to local demagnetization during rotation. Therefore, as described in the above embodiment, the permanent magnet at the end on the rear side with respect to the rotation direction is configured to have a region having a thickness larger than that of the other region on one end side. Local demagnetization of time can be suitably suppressed.

Further, each of the two permanent magnets 4 arranged symmetrically with respect to the virtual line A and forming the same magnetic pole is located on the far side from the virtual line in a cross section perpendicular to the rotation axis of the rotor. In addition, if the configuration has a region that is thicker than other regions, the local reduction during rotation that may occur at the end on the rear side with respect to the direction of rotation regardless of the direction of rotation of the rotor. Magnetism can be suitably suppressed. Furthermore, in the case of all the plurality of magnetic poles provided in the rotor 3 , the permanent magnets 4 having the same shape are inserted into all the magnet insertion holes provided in the rotor 3 . In this case, workability in assembling the motor 1 is also improved.

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.

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)
A local demagnetization when the permanent magnet 4 was incorporated in the rotor 3 of the motor 1 was determined 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 FIGS. 6 and 2) forming the permanent magnet 4 are such that the residual magnetic flux density Br at 20° C. is 1.35 [T] and the coercive force Hcj is 1500 [kA/m]. , the residual magnetic flux density Br at 150° C. 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 magnet 4B forming permanent magnet 4 is 2 mm, which is 40% of the height of magnet 4A.

In Example 1 configured as described above, the magnetization of the permanent magnet 4 is assumed to be 100% at 20° C. when no current is applied, and a three-phase alternating current with a peak current of 100 [A] is applied to the winding 6 at 1000 [rpm]. The rotor 3 was rotated at , further heated to 150° C., and then the demagnetization rate of magnetization when the temperature was returned to 20° C. was determined by the finite element method. Specifically, when the demagnetization rate of the area A1 having a radius of 0.2 mm at the corner of the rotor outer side of the magnet 4B shown in FIGS. 6A and 6B was obtained, it was 6.2%. there were.

(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. 7(A) and 4(C). Note that FIG. 4C is a schematic diagram showing the positional relationship between two magnets, and the dimensions of the magnets are more accurate in FIG. 7A than in FIG. 4C. 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, protrusions forming areas of increased thickness are formed on both opposing main surfaces. In Example 2 configured in this manner, as in Example 1, the area A2 (see FIGS. 7A and 7B) having a radius of 0.2 mm at the corner of the magnet 4D on the outer side of the rotor (see FIGS. 7A and 7B) was 14.2%.

(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 52 shown in FIGS. 8A and 4B. Note that FIG. 4B is a schematic diagram showing the positional relationship between two magnets, and the dimensions of the magnets are more accurate in FIG. 8A than in FIG. 4B. As with the permanent magnet 53 of the second embodiment, the permanent magnet 52 of the third embodiment has two magnets 4C and 4D arranged side by side along the long side direction (X-axis direction). In the permanent magnet 53 of Example 2, protrusions forming regions with a large thickness are formed on both opposing main surfaces, whereas in the permanent magnet 52 of Example 3, the protrusions are formed on the rotation axis. It is formed only on the main surface arranged on the side. In Example 3 configured as described above, as in Example 1, the area A3 (see FIGS. 8A and 8B) having a radius of 0.2 mm at the corner of the magnet 4D on the outer side of the rotor (see FIGS. 8A and 8B) was determined to be 21.8%.

(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. 9A. The permanent magnet 401 does not have a structure corresponding to the magnet 4B in the first embodiment, and instead of the magnet 4B, it has a laminated body such as a thin plate-like electromagnetic steel plate made of the same material as the core 7 . In Comparative Example 1 configured in this way, as in Example 1, the area A4 (see FIGS. 9A and 9B) having a radius of 0.2 mm at the corner of the permanent magnet 401 on the outer side of the rotor ) was found to be 38.9%.

As described above, the demagnetization rates of Examples 1 to 3 were all smaller than that of Comparative Example 1, and it was confirmed that local demagnetization during rotation of the rotor could be suppressed.

DESCRIPTION OF SYMBOLS 1... Motor 3... Rotor 4, 51-53... Permanent magnet 7... Core 4A, 4B, 4C... Magnet.

Claims (8)

A permanent magnet attached to a rotor of a motor, comprising:
It is composed by combining two plate-shaped magnets,
In a cross section orthogonal to the rotation axis of the rotor when attached to the rotor, one end has a region with a greater thickness than other regions,
The two magnets are stacked in the thickness direction of the permanent magnet,
the two magnets are oriented in the same direction,
a projecting portion that forms the thick region is provided only on a main surface that is arranged on the outer side of the rotor when the permanent magnet is attached to the rotor,
A permanent magnet having an L-shape in a cross section perpendicular to the rotation axis . A permanent magnet attached to a rotor of a motor, comprising:
Constructed by combining two rectangular plate- shaped magnets,
In a cross section orthogonal to the rotation axis of the rotor when attached to the rotor, one end has a region with a greater thickness than other regions,
When the permanent magnets are attached to the rotor, part of the main surface arranged on the outer side of the rotor protrudes to the outer side of the rotor. Formed, permanent magnet. 3. The permanent magnet according to claim 1, wherein said two magnets are combined along the longitudinal direction of said permanent magnet. The permanent magnet according to any one of claims 1 to 3, wherein the magnetic properties of said two magnets are the same as each other. a rotor having a plurality of magnet insertion holes;
a plurality of permanent magnets respectively accommodated in the plurality of magnet insertion holes;
A motor having
Some of the permanent magnets are configured by combining two plate-shaped magnets,
In a cross section orthogonal to the rotation axis of the rotor, one end side has a region with a greater thickness than other regions,
The two magnets are stacked in the thickness direction of the permanent magnet,
the two magnets are oriented in the same direction,
a projecting portion that forms the thick region is provided only on a main surface that is arranged on the outer side of the rotor when the permanent magnet is attached to the rotor,
A cross section orthogonal to the rotation axis has an L shape,
A motor, wherein an angle formed by a straight line extending from a main surface forming a long side of the L-shape and an imaginary line extending from the rotating shaft is within a range of 45° to 85°. a rotor having a plurality of magnet insertion holes;
a plurality of permanent magnets respectively accommodated in the plurality of magnet insertion holes;
A motor having
Some of the permanent magnets are configured by combining two rectangular plate- shaped magnets,
In a cross section orthogonal to the rotation axis of the rotor, one end side has a region with a greater thickness than other regions,
When the permanent magnets are attached to the rotor, part of the main surface arranged on the outer side of the rotor protrudes to the outer side of the rotor. formed ,
A motor, wherein an angle formed by a straight line extending from the main surface and an imaginary line extending from the rotation axis is within a range of 45° to 85°. The plurality of magnet insertion holes are arranged periodically around the rotation axis of the rotor,
Magnetic poles of the rotor are composed of permanent magnets inserted into one or more continuous magnet insertion holes among the plurality of magnet insertion holes,
Among the permanent magnets constituting the magnetic poles, the permanent magnets arranged at the rear end portion with respect to the rotation direction of the rotor are formed by combining two plate-shaped magnets, and the rotor rotates. 7. The motor according to claim 5, wherein, in a cross section orthogonal to the axis, one end side has a thicker region than other regions. The plurality of magnet insertion holes are arranged periodically around the rotation axis of the rotor,
Magnetic poles of the rotor are composed of two sets of permanent magnets inserted into two continuous magnet insertion holes out of the plurality of magnet insertion holes,
the two sets of permanent magnets forming the magnetic poles are arranged symmetrically with respect to the virtual line,
Each of the two sets of permanent magnets is configured by combining two plate-shaped magnets, and in a cross section orthogonal to the rotation axis of the rotor, another 7. A motor according to claim 5 or 6, having areas of greater thickness compared to areas.

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