JP6079132B2 - Embedded magnet rotor - Google Patents

Description

  The present invention relates to a magnet embedded rotor.

  In recent years, a motor (Internal Permanent Magnet Motor, IPM motor) having a structure in which a permanent magnet is embedded in a rotor is known. As a rotor used in this IPM motor, there is a rotor described in Patent Document 1.

  As shown in FIG. 8, the rotor 6 described in Patent Document 1 includes a cylindrical rotor core 60 having a structure in which a plurality of electromagnetic steel plates are laminated in the axial direction. On the outer peripheral side of the rotor core 60, a plurality of pairs of magnet insertion holes 61 and 62 separated by a bridge portion 63 are formed at equal angular intervals. A pair of permanent magnets 70 and 71 are inserted into the plurality of pairs of magnet insertion holes 61 and 62, respectively.

JP 2001-286110 A

  By the way, when the bridge part 63 exists between a pair of magnet insertion holes 61 and 62 like the rotor core 60 shown in FIG. 8, the magnetic flux emitted from the vicinity of the bridge part 63 in a pair of permanent magnets 70 and 71 is As indicated by the arrows in the figure, the bridge portion 63 passes through the outer periphery of the rotor core 60, that is, toward the stator. That is, since a leakage magnetic flux is generated in the bridge portion 63, the magnetic flux density on the outer peripheral surface of the rotor core 60 is reduced. As a result, the amount of effective magnetic flux interlinking with the stator coil is reduced, which is a factor that hinders the high output of the motor.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a magnet-embedded rotor capable of increasing the output torque of a motor.

In order to solve the above problems, a rotor core in which a plurality of pairs of magnet insertion holes separated by a bridge portion are formed in the circumferential direction and a permanent magnet inserted into each magnet insertion hole are provided, and a plurality of pairs In a magnet embedded rotor in which a pair of permanent magnets respectively inserted into the magnet insertion holes form one magnetic pole on the outer peripheral portion of the rotor core, the rotor core is between the pair of permanent magnets and from the bridge portion. Also, an auxiliary permanent magnet is provided on the outer peripheral side of the rotor core, and the auxiliary permanent magnet is formed with a tapered portion in which the circumferential width of the rotor core gradually decreases toward the bridge portion. The magnetic pole on the outer peripheral side of the rotor core is the same as the magnetic pole formed on the outer peripheral side of the rotor core by the pair of permanent magnets facing the auxiliary permanent magnet. The pole of the tapered portion of the stone, Unlike pole pair of the permanent magnets facing the auxiliary permanent magnet is formed on the outer peripheral side of the rotor core, the pair of permanent magnets, the rotor core around the bridge portion When the taper portion has a taper angle of “θ1” and the angle between the pair of permanent magnets on the outer periphery side of the rotor core is “θ2”. , it was Rukoto be formed so as to satisfy the relation of "θ1 <θ2".

According to this configuration, since the magnetic flux generated from the vicinity of the bridge portion in the pair of permanent magnets is absorbed by the tapered portion of the auxiliary permanent magnet, the leakage magnetic flux passing through the bridge portion can be reduced. Since the magnetic flux absorbed by the auxiliary permanent magnet is radiated to the outer peripheral side of the rotor core via the auxiliary permanent magnet, the magnetic flux density on the outer peripheral surface of the rotor core increases. As a result, the amount of effective magnetic flux interlinking with the stator coil increases, so that the output torque of the motor can be increased. Further, since the distance between the pair of permanent magnets located on the bridge portion side and the taper portion of the auxiliary permanent magnet is closer, the magnetic flux passing through the bridge portion can be effectively absorbed. Thereby, the reduction effect of leakage magnetic flux can be heightened.

In the magnet embedded rotor, the auxiliary permanent magnet is preferably a bonded magnet.
According to this configuration, the auxiliary permanent magnet having the shape as described above can be easily manufactured because the auxiliary permanent magnet is less likely to be restricted in shape.

  According to the magnet-embedded rotor, the output torque of the motor can be increased.

Sectional drawing which shows the cross-section of the IPM motor using the rotor about one Embodiment of a magnet embedded type rotor. Sectional drawing which shows the cross-section of the magnet embedded rotor of embodiment. Sectional drawing which shows the cross-section of the outer peripheral part about the magnet embedded type rotor of embodiment. Sectional drawing which shows the expanded sectional structure of the area | region A of FIG. Sectional drawing which shows the cross-section of the outer peripheral part about the modification of a magnet embedded type rotor. Sectional drawing which shows the cross-section of the outer peripheral part about the other modification of a magnet embedded type rotor. Sectional drawing which shows the cross-section of the outer peripheral part about the other modification of a magnet embedded type rotor. Sectional drawing which shows the cross-section of the conventional magnet embedded type rotor.

Hereinafter, an embodiment of an embedded magnet rotor will be described. First, the structure of an IPM motor using the magnet-embedded rotor of this embodiment will be described with reference to FIGS. 1 and 2.
As shown in FIG. 1, this IPM motor includes a cylindrical stator 2 fixed to the inner peripheral surface of a housing 1, an output shaft 3 rotatably supported by the housing 1 via a bearing (not shown), and an output shaft. 3 is provided with a rotor 4 that is integrally attached to the outer peripheral surface of 3.

  The stator 2 has a structure in which a plurality of electromagnetic steel plates are laminated in the axial direction. Twelve teeth 20 extending radially inward are formed on the inner peripheral surface of the stator 2. A stator coil 21 is wound around each tooth 20.

  As shown in FIG. 2, the rotor 4 includes a cylindrical rotor core 40 having a structure in which a plurality of electromagnetic steel plates are laminated in the axial direction. On the outer peripheral side of the rotor core 40, 10 sets of magnet groups 5 forming a set of three permanent magnets 50 to 52 are embedded at equal angular intervals in the circumferential direction. The set of magnet groups 5 forms one of the magnetic poles of the N pole and the S pole on the outer peripheral portion of the rotor core 40. The magnet group 5 that forms the N poles and the magnet group 5 that forms the S poles are alternately arranged along the circumferential direction of the rotor core 40, whereby 10 poles are formed on the rotor 4.

  In the motor configured as described above, when a three-phase current is supplied to the stator coil 21 shown in FIG. 1, a rotating magnetic field is formed by the stator 2. Torque is applied to the rotor 4 by attracting each magnet group 5 of the rotor 4 based on this rotating magnetic field, and the output shaft 3 rotates.

Next, the structure of the set of magnet groups 5 will be described in detail.
As shown in FIG. 3, on the outer peripheral side of the rotor core 40, a pair of magnet insertion holes 42 and 43 separated by a bridge portion 41 are formed so as to penetrate in the axial direction, and a magnet is interposed between them. An insertion hole 44 is formed. The pair of permanent magnets 50 and 51 inserted into the pair of magnet insertion holes 42 and 43 and the auxiliary permanent magnet 52 inserted into the magnet insertion hole 44 constitute a set of magnet groups 5.

  The pair of permanent magnets 50 and 51 are made of sintered magnets and inserted into the corresponding pair of magnet insertion holes 42 and 43 from the axial direction. The pair of permanent magnets 50 and 51 has a rectangular cross-sectional shape orthogonal to the axial direction of the rotor core 40 (the direction perpendicular to the paper surface). The pair of permanent magnets 50 and 51 are arranged so as to form a V shape that opens toward the outer peripheral side of the rotor core 40 around the bridge portion 41. When an N pole is formed on the outer periphery of the rotor core by a set of magnet groups 5, the pair of permanent magnets 50 and 51 are magnetized on the N pole on the outer periphery of the rotor core and on the S pole on the inner periphery of the rotor core as shown in the figure. Magnetized.

  The auxiliary permanent magnet 52 is also made of a sintered magnet and is inserted into the corresponding magnet insertion hole 44 from the axial direction. The auxiliary permanent magnet 52 is disposed between the pair of permanent magnets 50 and 51 and on the outer periphery side of the rotor core with respect to the bridge portion 41. As shown in FIG. 4, the auxiliary permanent magnet 52 has a pentagonal cross-sectional shape orthogonal to the axial direction of the rotor core 40, and the rotor core circumferential direction width is directed toward the bridge portion 41 at the inner peripheral side portion of the rotor core. It has a tapered portion 52a that becomes gradually thinner. The taper portion 52a is formed so as to satisfy the relationship of “θ1 <θ2” when the taper angle is “θ1” and the angle between the pair of permanent magnets 50 and 51 on the outer periphery side of the rotor core is “θ2”. . In addition, the dashed-dotted line in a figure has shown the centerline of each of a pair of permanent magnets 50 and 51. FIG. When N poles are formed on the outer peripheral portion of the rotor core 40 by the set of magnet groups 5, the auxiliary permanent magnet 52 has the tapered portion 52a magnetized to the S pole and the rotor core outer peripheral side to the N pole as shown in the figure. It is magnetized. That is, the magnetic pole on the outer periphery side of the rotor core of the auxiliary permanent magnet 52 is the same magnetic pole as the magnetic pole formed on the outer peripheral side of the rotor core by the pair of permanent magnets 50 and 51 facing the auxiliary permanent magnet 52. The magnetic pole of the taper portion 52a of the auxiliary permanent magnet 52 is different from the magnetic pole formed on the rotor core outer peripheral side by the pair of permanent magnets 50, 51 facing the auxiliary permanent magnet 52.

  The pair of magnet groups 5 forming the south pole on the outer peripheral portion of the rotor core 40 has the north pole and south pole of the pair of permanent magnets 50 and 51 and the auxiliary permanent magnet 52 illustrated in FIGS. Each of the structures is inverted.

  In the magnet insertion holes 42 and 43 of the rotor core 40, gaps G1 and G2 are formed outside the both sides of the short sides of the permanent magnets 50 and 51, respectively. Further, in the magnet insertion holes 42 and 43 of the rotor core 40, gaps G3 and G4 are formed on both outer sides of the long side surfaces of the permanent magnets 50 and 51 on the inner periphery side of the rotor core, respectively. Further, in the magnet insertion hole 44 of the rotor core 40, a gap G <b> 5 is formed outside both ends of the auxiliary permanent magnet 52 in the circumferential direction of the rotor core. These gaps G <b> 1 to G <b> 5 function as so-called flux barriers that prevent the magnetic flux from flowing around the pair of permanent magnets 50 and 51 and the auxiliary permanent magnet 52 in order to increase the magnetic flux density on the outer peripheral surface of the rotor core 40.

Next, the operation of the rotor 4 of this embodiment will be described.
As shown in FIG. 3, the magnetic flux generated from the vicinity of the bridge portion 41 in the pair of permanent magnets 50 and 51 is absorbed by the taper portion 52a of the auxiliary permanent magnet 52, as shown by the arrows in the drawing, so that the bridge The leakage magnetic flux passing through the portion 41 can be reduced. Moreover, in the present embodiment, the distance between the pair of permanent magnets 50 and 51 and the taper portion 52a of the auxiliary permanent magnet 52 is closer to the portion located on the bridge portion 41 side. Here, as shown in FIG. 4, the lengths of both side surfaces of the tapered portion 52a on the pair of permanent magnets 50 and 51 side are L1. Further, when the auxiliary permanent magnet 52 is projected onto the pair of permanent magnets 50 and 51 from the outer peripheral side to the inner peripheral side of the rotor core 40, the auxiliary permanent magnet 52 on the long side surface of the permanent magnets 50 and 51 is projected. Let L2 be the length of each part. Then, in this embodiment, since the relationship “θ1 <θ2” is satisfied, the length L1 is longer than the length L2. As a result, most of the magnetic flux emitted from the portion corresponding to the length L2 of the pair of permanent magnets 50 and 51 is absorbed by the portion corresponding to the length L1 of the tapered portion 52a having a larger surface area. The reduction effect can be enhanced. As shown in FIG. 3, since the magnetic flux absorbed by the auxiliary permanent magnet 52 is radiated from there to the outer peripheral side of the rotor core 40, the magnetic flux density on the outer peripheral surface of the rotor core 40 increases. As a result, the output torque of the motor can be increased.

  Further, in this way, if the leakage flux does not easily pass through the bridge portion 41, the width H of the bridge portion 41 in the circumferential direction of the rotor core shown in FIG. 4 can be increased, so that the strength of the rotor core 40 can be ensured. Thereby, for example, even when a centrifugal force is applied to a portion on the outer peripheral side of the magnet insertion holes 42 and 43 of the rotor core 40 when the rotor 4 rotates, it is difficult to be deformed so as to spread outward.

As described above, according to the magnet-embedded rotor of this embodiment, the following effects can be obtained.
(1) The rotor core 40 is provided with an auxiliary permanent magnet 52 between the pair of permanent magnets 50 and 51 and on the outer periphery side of the rotor core from the bridge portion 41. The auxiliary permanent magnet 52 is provided with a tapered portion 52a whose width in the circumferential direction of the rotor core gradually decreases toward the bridge portion 41. The magnetic poles on the outer periphery side of the rotor core of the auxiliary permanent magnet 52 are the same as the magnetic poles formed on the outer peripheral side of the rotor core by the pair of permanent magnets 50 and 51 facing the auxiliary permanent magnet 52. The magnetic pole of the taper portion 52a of the auxiliary permanent magnet 52 is different from the magnetic pole formed by the pair of permanent magnets 50 and 51 facing the auxiliary permanent magnet 52 on the outer periphery side of the rotor core. As a result, the magnetic flux density on the outer peripheral surface of the rotor core 40 increases, so that the output torque of the motor can be increased. In addition, the motor can be reduced in size.

  (2) When the taper angle of the auxiliary permanent magnet 52 is “θ1” and the angle between the pair of permanent magnets 50 and 51 on the outer periphery side of the rotor core is “θ2”, the relationship “θ1 <θ2” is established. It was decided to form so as to satisfy. As a result, the magnetic flux passing through the bridge portion 41 can be effectively absorbed, so that the effect of reducing the leakage magnetic flux can be increased, and the output torque of the motor can be further increased.

In addition, the said embodiment can also be implemented with the following forms which changed this suitably.
In the above embodiment, the cross-sectional shape perpendicular to the axial direction of the rotor core 40 of the auxiliary permanent magnet 52 is formed in a pentagonal shape, but instead, for example, a triangular shape as shown in FIG. 5 or as shown in FIG. You may form in a V shape. Even when the auxiliary permanent magnet 52 has a shape as shown in FIGS. 5 and 6, since the leakage magnetic flux passing through the bridge portion 41 can be reduced, the effective magnetic flux amount interlinked with the stator coil 21 is increased accordingly, and the motor The output torque can be increased. In short, the auxiliary permanent magnet 52 only needs to be formed with a tapered portion 52a in which the circumferential width of the rotor core 40 gradually decreases toward the bridge portion.

  -As shown in FIG. 7, you may set taper angle (theta) 1 of the taper part 52a larger than angle (theta) 2 which a pair of permanent magnets 50 and 51 make on the rotor core outer peripheral side. Even when the auxiliary permanent magnet 52 has a shape as shown in FIG. 7, the leakage magnetic flux passing through the bridge portion 41 can be reduced, so that the output torque of the motor can be increased.

  The shapes of the gaps G1 to G5 formed in the magnet insertion holes 42 to 44 of the rotor core 40 can be appropriately changed. The gaps G1 to G5 may not be provided in the magnet insertion holes 42 to 44 of the rotor core 40.

  In the above embodiment, the sintered magnet is used as the material for each of the pair of permanent magnets 50 and 51 and the auxiliary permanent magnet 52. However, for example, a bonded magnet may be used. Since it becomes difficult to receive shape restrictions by this, especially the auxiliary | assistant permanent magnet 52 which consists of the above shapes can be manufactured easily. Further, for example, when a bond magnet is embedded in the pair of magnet insertion holes 42 and 43 by injection molding, even if stress is applied to a portion outside the magnet insertion holes 42 and 43 of the rotor core 40 due to the injection pressure, the bridge portion The outward deformation is suppressed by 41.

  In the above embodiment, the pair of permanent magnets 50 and 51 are arranged so as to form a V shape with the bridge portion 41 as the center, but instead, for example, a U shape is formed with the bridge portion 41 as the center. You may arrange. In short, the present invention can be applied to any rotor core that includes a rotor core in which a plurality of pairs of magnet insertion holes separated by a bridge portion are formed in the circumferential direction and a permanent magnet that is inserted into each magnet insertion hole. It is.

  DESCRIPTION OF SYMBOLS 4 ... Magnet embedded type rotor, 40 ... Rotor core, 41 ... Bridge part, 42, 43 ... Magnet insertion hole, 50, 51 ... Permanent magnet, 52 ... Auxiliary permanent magnet, 52a ... Tapered part, 60 ... Rotor core.

Claims (2)

A rotor core in which a plurality of pairs of magnet insertion holes separated by a bridge portion are formed in the circumferential direction;
A permanent magnet inserted into each magnet insertion hole,
In a magnet-embedded rotor in which a pair of permanent magnets respectively inserted into a plurality of pairs of magnet insertion holes forms one magnetic pole on the outer peripheral portion of the rotor core,
The rotor core is provided with an auxiliary permanent magnet between the pair of permanent magnets and on the outer peripheral side of the rotor core from the bridge portion,
The auxiliary permanent magnet is formed with a tapered portion in which the circumferential width of the rotor core gradually decreases toward the bridge portion,
The magnetic pole on the outer peripheral side of the rotor core of the auxiliary permanent magnet is the same as the magnetic pole formed on the outer peripheral side of the rotor core by the pair of permanent magnets facing the auxiliary permanent magnet, and the tapered portion of the auxiliary permanent magnet poles, Unlike pole pair of the permanent magnets facing the auxiliary permanent magnet is formed on the outer peripheral side of the rotor core,
The pair of permanent magnets are arranged so as to form a V shape that opens toward the outer peripheral side of the rotor core around the bridge portion,
When the taper portion has a taper angle “θ1” and an angle formed by the pair of permanent magnets on the outer peripheral side of the rotor core is “θ2”,
θ1 <θ2
Magnet-embedded rotor is formed to satisfy the relationship: characterized Rukoto. The embedded magnet rotor according to claim 1,
A magnet embedded rotor, wherein the auxiliary permanent magnet is a bonded magnet.