JP2019083678A - Permanent magnet and motor - Google Patents

Abstract

To realize manufacturing at low cost and enable suppression of local demagnetization at the time of rotation of a rotor.SOLUTION: A permanent magnet 4 is attached to a rotor 3 of a motor 1 and is configured by combining a plurality of plate-like magnets 4A and 4B, and in a cross section orthogonal to the rotation axis of the rotor 3 when the permanent magnet is attached to the rotor 3, the permanent magnet 4 includes an area with a greater thickness on one end side compared to the other area.SELECTED DRAWING: Figure 2

Description

  The present invention relates to permanent magnets and motors.

  In a magnet embedded motor in which a permanent magnet is embedded with respect to a rotor, a permanent magnet may be demagnetized by a demagnetizing field generated when the rotor rotates. On the other hand, for example, in Patent Document 1, the heavy rare earth element is diffused to a part of the magnet by adhering the heavy rare earth element to the surface of the magnet and diffusing the heavy rare earth element to the inside by heat treatment. A technique is disclosed for forming a magnet having regions different in coercive force by forming the regions.

JP, 2012-4147, A

  However, in the technology described in Patent Document 1, the heavy rare earth element used to increase the coercive force of the magnet is basically expensive and thus the cost increases. Moreover, the operation | work cost which concerns on diffusion of heavy rare earth elements, such as heat processing, also generate | occur | produces.

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

  In order to achieve the above object, the permanent magnet according to the present invention is a permanent magnet attached to a rotor of a motor, and is configured by combining a plurality of plate-like magnets, and when attached to the rotor In a cross section orthogonal to the axis of rotation of the child, one end side has a region having a larger thickness than the other region.

  A motor according to an aspect of the present invention is a motor including a rotor having a plurality of magnet insertion holes, and a plurality of permanent magnets respectively accommodated in the plurality of magnet insertion holes, wherein the permanent magnet A part of the two is formed by combining a plurality of plate-like magnets, and in a cross section orthogonal to the rotation axis of the rotor, a region having a larger thickness on one end side compared to the other region Have.

  According to the above-described permanent magnet and motor, the permeance coefficient of the permanent magnet can be adjusted by forming the region where the thickness of the permanent magnet is large on one end side. Therefore, providing a region having a large thickness on one end side of the permanent magnet suppresses local demagnetization that may occur when the rotor rotates when the permanent magnet is attached to the rotor. be able to. Moreover, said permanent magnet is comprised combining the plate-shaped several magnet. Therefore, a permanent magnet having a large thickness region can be manufactured inexpensively, and an increase in cost can be suppressed.

  Here, in the above-mentioned permanent magnet, the plurality of magnets may be overlapped in the thickness direction of the permanent magnet.

  With such a configuration, the permanent magnet can be manufactured by combining magnets of small thickness, and the amount of magnet used as the permanent magnet can be minimized, thereby suppressing costs. Permanent magnets can be manufactured.

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

  With such a configuration, it is possible to combine magnets that are relatively easy to handle, and it is possible to suppress an increase in assembly cost and the like.

  In addition, when the permanent magnet is attached to the rotor, a part of the main surface disposed on the outer side of the rotor protrudes to form a region in which the thickness is large. be able to.

  Permanent magnets are susceptible to local demagnetization during rotation outside the rotor. Then, local demagnetization at the time of rotation can be suitably suppressed by setting it as the structure to which a part of the principal surface by the side of the outside of a rotor protrudes.

  In the motor described above, 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 of the plurality of magnet insertion holes. The permanent magnet constitutes a magnetic pole of the rotor, and among the permanent magnets constituting the magnetic pole, the permanent magnet disposed at the end on the rear side with respect to the rotational direction of the rotor is a plate A plurality of magnets may be combined, and in the cross section orthogonal to the rotation axis of the rotor, one end side may have a region having a thickness greater than that of the other region.

  Among the permanent magnets attached to the rotor and constituting the magnetic pole, the permanent magnet at the end on the rear side in the rotational direction is susceptible to local demagnetization during rotation. Therefore, local demagnetization at the time of rotation is preferable by configuring the permanent magnet on the end on the rear side with respect to the rotation direction to have a region on one end side that is thicker than the other region. Can be suppressed.

  Also, the plurality of magnet insertion holes are periodically arranged around the rotation axis of the rotor, and two permanent magnets are inserted into two consecutive magnet insertion holes of the plurality of magnet insertion holes. The magnetic poles of the rotor are configured, the two permanent magnets constituting the magnetic poles are arranged symmetrically with respect to a virtual line, and the two permanent magnets are respectively combined with a plurality of plate-shaped magnets. The cross section orthogonal to the rotation axis of the rotor may be configured to have an area having a thickness greater than that of the other area on the end side farther from the virtual line.

  As described above, in a cross section orthogonal to the rotation axis of the rotor, each of two permanent magnets disposed symmetrically with respect to the imaginary line and constituting the same magnetic pole is an end far from the imaginary line By having a configuration in which the thickness is larger than the other regions on the side, the rotational locality that may occur at the rear end with respect to the rotational direction regardless of the rotational direction of the rotor Demagnetization can be suitably suppressed.

  According to the present invention, it is possible to provide a permanent magnet that can be manufactured at low cost and that can suppress local demagnetization during rotation of a rotor, and a motor to which the permanent magnet is applied.

1 is a schematic plan view of a motor according to an embodiment of the present invention. It is a schematic perspective view explaining the composition 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 the combination of a magnet. It is a figure which shows the example of a change of arrangement | positioning of the permanent magnet in the core of a rotor. (A) is a figure explaining the demagnetizing factor of magnetization of Example 1, (B) is a partially expanded view of (A). (A) is a figure explaining the demagnetizing factor of magnetization of Example 2, (B) is a partially expanded view of (A). (A) is a figure explaining the demagnetizing factor of magnetization of Example 3, (B) is a partially expanded view of (A). (A) is a figure explaining the demagnetizing factor of magnetization of the comparative example 1, (B) is a partially expanded view of (A).

  Hereinafter, with reference to the accompanying drawings, modes for carrying out the present invention will be described in detail. In the description of the drawings, the same elements will be denoted by the same reference symbols, without redundant description. Moreover, this invention is not limited to the following embodiment, It is possible to make various changes.

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

  As shown in FIG. 1, the motor 1 includes a stator 2, a rotor 3 rotatably disposed inside the stator 2, and a shaft 8 connected to the core 7 of the rotor 3. And is configured. The motor 1 is a so-called magnet embedded motor (IPM motor) in which permanent magnets 4 are embedded in the 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 on the inner circumferential surface of the stator 2 at equal intervals, 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 accommodated and fixed in the plurality of magnet insertion holes.

  The core 7 is formed of a laminate of thin electromagnetic steel plates or the like. An axial hole is formed in a central portion of the core 7, and a shaft 8 serving as an axis of rotation of the rotor 3 is fitted in the axial hole. Near the outer periphery of the core 7, plural pairs (four pairs in FIG. 1) of magnet insertion holes are provided 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 an imaginary line (an imaginary line A shown in FIG. 3) extending from the axis of the core 7. The two permanent magnets 4 accommodated in the two (one pair) magnet insertion holes arranged in contrast to the virtual line A are arranged such that the outside of the core 7 has the same pole, one pole Are configured. In the case of the motor 1 shown in FIG. 1, the number of poles of the rotor 3 is four.

  The permanent magnet 4 shown in FIG. 2 is accommodated in the magnet insertion hole. In the present 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. Note that FIG. 2 shows an XYZ orthogonal coordinate system for the purpose of explanation.

  As shown in FIG. 2, the permanent magnets 4 are arranged so as to overlap along the direction orthogonal 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 consists of two plate-like magnets 4A and 4B. More specifically, the magnets 4A and 4B have a rectangular plate shape. In addition, the "plate-like" magnet in this embodiment is a magnet in which the principal surfaces opposingly arranged are substantially parallel to each other. Therefore, for example, a magnet having a substantially parallel main surface but having inclined side surfaces or rounded corners of the main surface is included in the “plate-like” magnet.

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 formed of rare earth based permanent magnets, and can be, for example, RTB based permanent magnets. Further, among them, an RTB-based sintered magnet can be obtained. The RTB-based sintered magnet has particles (crystal particles) composed of R ₂ T ₁₄ B crystals and grain boundaries.

  R in the RTB based sintered magnet represents at least one of rare earth elements. The rare earth elements mean Sc, Y and lanthanoid elements belonging to the third group of the long period periodic table. The lanthanoid element includes, for example, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu and the like. T in the RTB based 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 the present embodiment may contain Cu, Al or the like. The addition of these elements makes it possible to increase the coercivity, increase the corrosion resistance, or improve the temperature characteristics of the magnetic properties.

  Furthermore, the RTB-based sintered magnet according to the present embodiment may contain Dy, Tb, or both as a heavy rare earth element. Heavy rare earth elements may be contained in crystal grains and grain boundaries. When the heavy rare earth element is substantially not contained in the crystal grains, it is preferably contained in the grain boundary. The concentration of heavy rare earth elements at grain boundaries is preferably higher than the concentration in crystal grains. The RTB-based sintered magnet according to the present embodiment may be a RTB-based sintered magnet in which heavy rare earth elements are diffused at grain boundaries. R-T-B sintered magnets in which heavy rare earth elements are diffused at grain boundaries are smaller in residual amount of heavy rare earth elements as compared with R-T-B sintered magnets that do not diffuse at grain boundaries, and residual magnetic flux density and coercivity Can be improved. When the RTB-based sintered magnet in which heavy rare earth elements are diffused at grain boundaries is used as the magnets 4A and 4B according to this embodiment, the heavy rare earth elements are not diffused at grain boundaries in a part of the magnet. , It is possible to use those which are grain boundary diffused throughout the magnet. Such a configuration improves productivity and reduces costs.

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

  When a cold-formed body obtained by forming the raw material powder at room temperature is hot-pressed while being heated, the pores remaining in the cold-formed body disappear and the sintered body is not used. It can be densified. Furthermore, an RTB-based permanent magnet having a desired shape and having magnetic anisotropy by performing hot extrusion processing as hot processing on a molded body obtained by hot molding You can get

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

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

  The magnets 4A and 4B preferably have the same short side length, and when the magnets 4A and 4B are overlapped as shown in FIG. It is preferable that the ends of the side surfaces parallel to the XY plane) coincide with each other.

  The magnets 4B are stacked such that the short sides on one side of the magnets 4A overlap in plan view. In the present embodiment, one short side 41A (short side on the X-axis negative side) included in the main surface 40A of the magnet 4A (surface parallel to the XZ plane) and the main surface 40B of the magnet 4B (parallel to the XZ plane) Magnet 4B is laminated on magnet 4A in the state where principal surface 40A and principal surface 40B opposed in a state where one short side 41B (short side on the X axis negative side) included in the surface) overlaps. As a result, when looking at the permanent magnet 4 along the long side direction (X axis direction) of the permanent magnet 4, the one side (on the X axis negative side where the magnets 4 A and 4 B are laminated) 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 in which the magnet 4B is not stacked on the magnet 4A). Thus, the permanent magnet 4 which concerns on this embodiment has the area | region where the thickness of the permanent magnet 4 mutually differs. The permanent magnet 4 has a substantially L-shaped cross section (plane parallel to the XY plane).

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

  The magnets 4A and 4B may be joined by an adhesive or the like. In addition, a bonding layer may be interposed between the magnets 4A and 4B. When the 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.

  FIG. 3 is a partially enlarged view of FIG. The permanent magnet 4 is disposed as shown in FIG. 3 by being accommodated in a magnet insertion hole (not shown) provided in the core 7 of the rotor 3.

  Each pair of permanent magnets 4 is arranged in contrast to an imaginary line A extending from the axis of the core 7. More specifically, in the permanent magnet 4, the angle formed by the straight line extended from the substantially L-shaped long side (long side portion formed by the magnet 4 A) and the imaginary line A is a predetermined angle (for example, 45 °) It arranges contrastingly in the state inclined only by -85 degrees, although it does not specifically limit. Thus, the permanent magnet 4 is accommodated in the magnet insertion hole such that the upper side (the Y-axis positive side) in FIG. 2 faces the outer peripheral side of the core 7. Moreover, when accommodated in the magnet insertion hole, the cross section orthogonal to the rotation axis of the rotor 3 (core 7) in the permanent magnet 4 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 the thickness of the permanent magnet 4 (extension of the shaft 8) at both ends far from the imaginary line A (side close to the outer periphery of the rotor 3). The thickness in the stacking direction of the permanent magnet 4 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 The thickness of the permanent magnet 4 is smaller at both ends closer to the imaginary line A (closer to the rotation axis of the rotor 3).

  The permanent magnet 4 can be fixed in the magnet insertion hole by filling the magnet insertion hole with a filler as appropriate. A thermosetting resin can be used as a filler, For example, an epoxy resin, a silicone resin, etc. can be used. However, if the permanent magnet 4 stored in the magnet insertion hole is fixed to the magnet insertion hole, the filler need not necessarily be used.

  As described above, the permanent magnet 4 according to the present embodiment has, on one end side, a region having a thickness larger than that of the other region. In the case of the permanent magnet 4, the area where the magnet 4B on one end side is overlapped is thicker than the other area (the area where the magnet 4B is not overlapped). More specifically, in the cross section orthogonal to the rotation axis of the rotor 3 (the cross section parallel to the main surface of the 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 where demagnetization is likely to occur.

  In general, it is known that, in a motor to which a permanent magnet is attached, the rotation of the rotor causes a magnetic field (reverse magnetic field) reverse to the magnetization direction of the partial magnet. Although the area to which the reverse magnetic field is applied changes depending on the arrangement of the permanent magnets, etc., for example, it is known that the reverse magnetic field is applied to the end on the rear side (the side opposite to the rotation direction) . For example, assuming that the arrow R shown in FIG. 3 is the rotation direction 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 a concern that demagnetization of the permanent magnet will occur in the area where the reverse magnetic field is generated. On the other hand, conventionally, it has been common to prevent demagnetization by increasing the coercive force of the material, such as incorporating a heavy rare earth element in the magnet material. However, heavy rare earth elements are expensive, which increases the material cost of the magnet. In view of this point, for example, although the heavy rare earth element is contained only in a partial region using diffusion by heat treatment, etc., the material cost for containing the heavy rare earth element is still expensive. At the same time, heat treatment is required, so it can not 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 the present embodiment, one end side on which the magnet 4B is overlapped is thicker than the other region. That is, the permeance coefficient of the permanent magnet 4 can be adjusted by forming the region where the thickness of the permanent magnet 4 is large in the cross section orthogonal to the rotation axis of the rotor 3 on one end side. The permeance coefficient is the thickness in the magnetization direction of the magnet, 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) It changes according to the ratio of. Further, in the magnet, a region having a small permeance coefficient is susceptible to demagnetization due to the influence of the reverse magnetic field or the like. Therefore, in the permanent magnet 4, when the permanent magnet 4 is attached to the rotor 3 by providing a region having a large thickness on one end side of the permanent magnet 4 susceptible to the reverse magnetic field, the rotor It is possible to suppress local demagnetization that may occur at the time of rotation of 3. That is, by arranging a region having a large thickness in the permanent magnet 4 in the region where the reverse magnetic field is likely to be applied, demagnetization in the region can be suppressed.

  Further, the permanent magnet 4 is configured by combining a plurality of plate-like magnets 4A and 4B. If it is going to manufacture the magnet of shape like permanent magnet 4, manufacturing cost will increase. On the other hand, since the plate-like magnets 4A and 4B can be manufactured by a general manufacturing method, an increase in cost can be suppressed. Further, in the permanent magnet 4, local demagnetization can be suppressed by combining the plurality of magnets 4A and 4B and changing the thickness thereof. Thus, instead of changing the material, a permanent magnet 4 having a region of different thickness in a cross section orthogonal to the rotation axis of the rotor 3 is obtained by combining a plurality of plate-like magnets 4A and 4B. As well as being able to be manufactured at low cost, local demagnetization during rotation of the rotor can be suppressed.

  The region where the thickness of the permanent magnet 4 increases in the cross section orthogonal to the rotation axis of the rotor 3 is formed on the “one end side” with respect to the rotation axis of the rotor 3. It means that the area | region where the thickness of the permanent magnet 4 becomes large in the cross section which orthogonally crosses is provided not only near the center of the permanent magnet 4 but at the end. In the permanent magnet of the present embodiment, the area having a large thickness is formed at one end and the area where the magnet 4B extends from the end, but the "area having a large thickness" is one of the permanent magnets. It does not have to be provided including the end. For example, by rounding the corner of the permanent magnet 4 or the like, the area inside the end may be a "thick area".

  Further, the permanent magnet 4 forms a region having a large thickness by overlapping the plate-like magnets 4A and 4B. Therefore, as shown in FIG. 2, as the permanent magnet 4, the lower (Y-axis negative side) main surface is formed by the main surface opposite to the one main surface 40 A of the magnet 4 A, and is flat It has become. That is, the main surface disposed on the rotary shaft side when housed in one of the magnet insertion holes of permanent magnet 4 is a flat surface, and rotation is achieved when magnet 4B is stacked and housed in the magnet insertion hole on the other side. By projecting a part of the main surface arranged outward with respect to the axis, a region having a large thickness is formed. However, how to form a region having a large thickness in the permanent magnet 4 can be changed as appropriate. Further, the combination of the magnets constituting the permanent magnet 4 can be appropriately changed.

  FIG. 4 is a modification of the combination of two magnets in a permanent magnet. FIGS. 4A to 4C each show a cross-sectional view of a permanent magnet according to a modification (a cross-sectional view in a cross section orthogonal to the rotation axis of the rotor). In FIGS. 4A to 4C, permanent magnets are formed by combining two magnets 4C and 4D different in thickness from each other.

  The permanent magnet 51 shown in FIG. 4 (A) has a thickness in place of forming a region having a large thickness by overlapping the two magnets 4A and 4B in the thickness direction as described in the above embodiment. By combining the magnets 4C and 4D different from each other and arranging them along the long side direction (X-axis direction) of the permanent magnet 4, a region having a large thickness is formed. Thus, how to combine a plurality of magnets when forming a permanent magnet having a region having a large thickness as compared to other regions can be appropriately changed. In addition, even when changing the combination method of a magnet, a permanent magnet can be manufactured at low cost by combining plate-shaped magnets and forming a permanent magnet. Also, when forming a permanent magnet by arranging magnets along the long side direction (X-axis direction) like the permanent magnet 51, compared to the case where the magnets are stacked in the thickness direction (Y-axis direction), It is conceivable that the generated eddy current loss can be reduced.

  The permanent magnet 52 shown in FIG. 4B is the same as the permanent magnets 4 and 51 in that a region having a large thickness is formed by the projection of a part of the main surface on one side, but the projection is The surface on which the area to be formed is formed is different. That is, it differs from the permanent magnet 51 in that a part of the main surface (main surface on the lower side in the figure) disposed on the rotary shaft side protrudes when the permanent magnet 52 is accommodated in the magnet insertion hole. As described above, the arrangement of the protrusions when forming the regions having different thicknesses in the permanent magnet is not limited to the surface disposed outward with respect to the rotation axis when accommodated in the magnet insertion hole.

  The permanent magnet 53 shown in FIG. 4C is different from the other permanent magnets in that a part of both main surfaces of the permanent magnet is formed with a projecting region as compared with the other regions. As shown in FIG. 4C, in the case where a projecting region is formed in a part of both of the opposing main surfaces in comparison with the other region, the permanent magnet 53 has a cross section (parallel to the XY plane). The surface is approximately T-shaped. As described above, even if the cross-sectional shape of the permanent magnet 53 is not substantially L-shaped but substantially T-shaped, the permeance coefficient in the region can be increased by forming the region having a large thickness. Therefore, local demagnetization at the time of rotation of a rotor can be suppressed like permanent magnet 4 grade | etc.,.

  The combination of the permanent magnet 52 shown in FIG. 4B and the magnets when forming the permanent magnet 53 shown in FIG. 4C can be appropriately changed. For example, three magnets may be combined to form a permanent magnet.

  FIG. 5 shows a modification of the arrangement of permanent magnets accommodated in the core 7 of the rotor 3 in the motor 1. As shown in FIGS. 1 and 3, in the above embodiment, the case where one permanent magnet 4 in the rotor 3 is symmetrically arranged with respect to the imaginary line A has been described in the above embodiment, but in the above embodiment The permanent magnet 4 and permanent magnets of other shapes may be combined to form one magnetic pole in the rotor 3. In addition, in FIG. 5, the description of the magnet insertion hole is omitted.

  In FIG. 5 (A), permanent magnets 4 having a large area of thickness constituted by magnets 4A and 4B are arranged as permanent magnets on the right side in the figure, which are rearward with respect to the rotational direction of rotor 3 indicated by arrow R. However, only the magnet 4A is disposed as a permanent magnet on the left side in the figure, which is rearward with respect to the rotational direction of the rotor 3 indicated by the arrow R. Thus, the arrangement of the permanent magnets can be appropriately changed in consideration of the area to which the reverse magnetic field is applied. At this time, it is not necessary to set it as the target for the virtual line.

  In FIG. 5B, the permanent magnets 4 described in the above embodiment are disposed as a pair of permanent magnets, and a flat plate-shaped magnet 4E different from the magnets 4A and 4B is disposed between them. In the example shown in FIG. 5 (B), three permanent magnets arranged in series constitute a magnetic pole. As described above, the number of permanent magnets forming one magnetic pole in the rotor 3 may be one or more, and the number and arrangement thereof can be appropriately changed.

  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 permanent magnet 4 is formed by forming the region where the thickness of the permanent magnet 4 is large on one end side. The permeance factor of 4 can be adjusted. Therefore, when an area having a large thickness is provided on one end side of the permanent magnet 4, a local reduction that may occur when the rotor 3 rotates when the permanent magnet 4 is attached to the rotor 3 Magnetism can be suppressed. Moreover, said permanent magnet 4 is comprised combining several plate-shaped magnet 4A, 4B. Therefore, the permanent magnet 4 having a region with a large thickness can be manufactured inexpensively, and an increase in cost can be suppressed.

  Further, in the above-mentioned permanent magnet, a plurality of magnets 4A and 4B are stacked in the thickness direction of the permanent magnet 4, thereby combining the magnets of small thickness to manufacture the above-mentioned permanent magnet. Therefore, the permanent magnet can be manufactured while suppressing the cost associated with the magnetization and the like.

  In addition, when the permanent magnet 4 is attached to the rotor 3, a part of the main surface disposed on the outer side of the rotor 3 protrudes to form a region having a large thickness. Thus, it is possible to preferably suppress the influence of local demagnetization during rotation outside the rotor.

  Further, among the permanent magnets attached to the rotor 3 of the motor 1 and constituting the magnetic poles, the permanent magnet 4 at the end on the rear side in the rotational direction is susceptible to local demagnetization during rotation. Therefore, as described in the above embodiment, the permanent magnet on the end on the rear side with respect to the rotational direction has a configuration in which one end has an area larger in thickness than the other area, so that the rotation is performed. The local demagnetization at the time can be suitably suppressed.

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

  The present invention is not limited to the above embodiment, and various modifications can be made without departing from the scope of the invention.

  For example, the number of magnet insertion holes provided in the motor can be appropriately increased or decreased, and the positional relationship of the magnet insertion holes can be appropriately changed. Moreover, the number of the magnets which comprise a permanent magnet can be changed suitably. Moreover, the shape can also be changed suitably.

  The contents (effects and the like) 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 local demagnetization when the permanent magnet 4 was incorporated into the rotor 3 of the motor 1 was determined using the finite element method. The motor 1 is provided with a stator 2 having 24 slots (not shown), and the winding 6 is wound 30 turns by concentrated winding 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 is provided with 16 pairs of magnetic poles showing one N pole or S pole by a pair of permanent magnets 4 as shown in FIG. Thus, the motor 1 is an inner rotor type IPM motor of 16 poles and 24 slots.

  The magnetic properties of the magnets 4A and 4B (see FIG. 6 and FIG. 2) forming the permanent magnet 4 have a residual magnetic flux density Br of 1.35 [T] and a coercive force Hcj of 1500 [kA / m] at 20.degree. The residual magnetic flux density Br at 150 ° C. is 1.1745 [T], and the coercive force Hcj is 570 [kA / m]. The long side length of the magnet 4A which forms the permanent magnet 4 is 11.6 mm, and the height is 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.

  In Example 1 configured as described above, the magnetization of the permanent magnet 4 at 100 ° C. with no current applied is 100%, and a three-phase alternating current with a peak current of 100 [A] is applied to the winding 6 at 1000 [rpm] After rotating the rotor 3 at 150 ° C. and further heating to 150 ° C., the demagnetizing factor of the magnetization when returned to 20 ° C. was determined by the finite element method. Specifically, the demagnetizing factor of an area A1 having a radius of 0.2 mm at the outer corner of the rotor of the magnet 4B shown in FIGS. 6A and 6B is 6.2%. there were.

(Example 2)
The second embodiment is the same as the first embodiment except that the permanent magnet 4 in the first embodiment is replaced by the permanent magnet 53 shown in FIGS. 7A and 4C. FIG. 4C is a schematic view for illustrating the arrangement relationship of the two magnets, and FIG. 7A is more accurate than FIG. 4C regarding the dimensions of the magnets. In the permanent magnet 53, two magnets 4C and 4D having different thicknesses are used instead of the two magnets 4A and 4B in the thickness direction as in the permanent magnet 4 of the first embodiment. ) Are arranged side by side, and an area having a large thickness is formed. The magnet 4D is thicker than the magnet 4C. In the permanent magnet 53, protrusions forming a region having a large thickness are formed on both of the opposing main surfaces. Also in the second embodiment configured as above, as in the first embodiment, an area A2 having a radius of 0.2 mm of the corner on the outer side of the rotor of the magnet 4D (see FIGS. 7A and 7B) The demagnetization factor of was determined to be 14.2%.

(Example 3)
The third embodiment is the same as the first embodiment except that the permanent magnet 4 in the first embodiment is replaced with the permanent magnet 52 shown in FIGS. 8A and 4B. 4 (B) is a schematic view for showing the arrangement relationship of two magnets, and FIG. 8 (A) is more accurate than FIG. 4 (B) about the dimension of a magnet. Similar to the permanent magnet 53 of the second embodiment, in the permanent magnet 52 of the third embodiment, two magnets 4C and 4D are arranged side by side along the long side direction (X-axis direction). In the permanent magnet 53 of the second embodiment, the projections forming the region having a large thickness are formed on both of the opposing main surfaces, whereas in the permanent magnet 52 of the third embodiment, the above-mentioned projection is the rotation shaft It is formed only on the main surface disposed on the side. Also in the third embodiment thus configured, as in the first embodiment, a region A3 having a radius of 0.2 mm of the corner on the outer side of the rotor of the magnet 4D (see FIGS. 8A and 8B) Of the demagnetizing factor of 21.8%.

(Comparative example 1)
The comparative example 1 is the same configuration as the example 1 except that the permanent magnet 4 in the example 1 is replaced with the permanent magnet 401 shown in FIG. 9A. The permanent magnet 401 is not provided with the configuration corresponding to the magnet 4B in the first embodiment, and is provided with a laminated body such as a thin plate-like electromagnetic steel plate of the same material as the core 7 instead of the magnet 4B. Also in the comparative example 1 configured as above, as in the example 1, the area A4 having a radius of 0.2 mm of the corner on the outer side of the rotor of the permanent magnet 401 (see FIGS. 9A and 9B) It was 38.9% when the demagnetizing factor of was obtained.

  As described above, it was confirmed that all of the demagnetizing factors of Examples 1 to 3 were smaller than the demagnetizing factor of Comparative Example 1, and it was possible to suppress the local demagnetization during the rotation of the rotor.

  DESCRIPTION OF SYMBOLS 1 ... motor, 3 ... rotor, 4, 51-53 ... permanent magnet, 7 ... core, 4A, 4B, 4C ... magnet.

Claims (7)

A permanent magnet attached to the rotor of the motor,
It is constructed by combining a plurality of plate-like magnets,
A permanent magnet having, in a cross section orthogonal to the rotation axis of the rotor when attached to the rotor, a region having a thickness greater than that of the other region on one end side.   The permanent magnet according to claim 1, wherein the plurality of magnets are stacked in the thickness direction of the permanent magnet.   The permanent magnet according to claim 1, wherein the plurality of magnets are combined along the long side direction of the permanent magnet.   The area | region where the said thickness is large is formed because a part of main surface arrange | positioned on the outward side of the said rotor protrudes, when the said permanent magnet is attached to the said rotor. The permanent magnet according to any one of 3. 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 a plurality of plate-like magnets,
A motor having a region having a large thickness at one end side compared to the other region in a cross section orthogonal to the rotation axis of the rotor. The plurality of magnet insertion holes are periodically arranged around the rotation axis of the rotor, and
The magnetic poles of the rotor are configured by permanent magnets inserted into one or more continuous magnet insertion holes of the plurality of magnet insertion holes,
Among the permanent magnets constituting the magnetic pole, the permanent magnets arranged at the end on the rear side with respect to the rotation direction of the rotor are configured by combining a plurality of plate-like magnets, and the rotation shaft of the rotor The motor according to claim 5, wherein in a cross section perpendicular to the surface, the one end side has a region having a thickness greater than that of the other region. The plurality of magnet insertion holes are periodically arranged around the rotation axis of the rotor, and
Two permanent magnets inserted into two consecutive magnet insertion holes of the plurality of magnet insertion holes constitute magnetic poles of the rotor,
The two permanent magnets constituting the magnetic pole are disposed symmetrically with respect to a virtual line,
The two permanent magnets are each configured by combining a plurality of plate-like magnets, and in a cross section orthogonal to the rotation axis of the rotor, on the end side far from the virtual line, another area and The motor according to claim 5, wherein the motor has a region of greater thickness.

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