JP2014082882A - Magnet embedded type rotor and method of manufacturing magnet embedded type rotor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnet embedded type rotor capable of securing output torque of a motor although a rotor core comprises a plurality of split cores.SOLUTION: A magnet embedded type rotor includes a cylindrical rotor core and a permanent magnet 42 embedded in the rotor core. The rotor core has a split core 41, having an N pole on an outer peripheral side, and a split core 41, having an S pole on the outer peripheral side, alternately in a peripheral direction. Here the split core 41 is so molded as to satisfy "α>360°/n", where α is the angle "°" that both end faces in the peripheral direction contain and "n" is the number of split cores 41.

Description

  The present invention relates to a magnet-embedded rotor and a manufacturing method thereof.

  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.

  The rotor described in Patent Document 1 includes a cylindrical rotor core in which a plurality of magnet insertion holes are formed, and a plurality of permanent magnets embedded in the rotor core. The rotor core is configured to be divided at equal angular intervals in the circumferential direction by a plurality of divided cores having a substantially fan shape. A fitting portion including a concave portion and a convex portion that can be fitted is formed on opposing surfaces of the divided cores adjacent to each other, and the adjacent divided cores are connected to each other in the circumferential direction through the fitting portion. The rotor core is configured by assembling all the divided cores into a cylindrical shape through such a fitting structure.

Japanese Patent Laid-Open No. 2002-262496

  By the way, when the split cores adjacent to each other are coupled using the fitting portion as in the rotor described in Patent Document 1, it is difficult to closely contact the facing surfaces, and a gap is formed between the adjacent split cores. End up. If such a gap exists between the permanent magnets constituting the magnetic poles in the rotor, it becomes a large magnetic resistance for the magnetic circuit of the rotor, so that the amount of magnetic flux generated from the rotor is reduced. This is a factor that reduces the output torque 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 that can secure the output torque of the motor while the rotor core is composed of a plurality of divided cores, and a method for manufacturing the same. There is to do.

  In order to solve the above problems, a cylindrical rotor core and a plurality of permanent magnets embedded in the rotor core are provided, and the rotor core has a split core having an N pole on the outer peripheral side, and an S pole on the outer peripheral side. In a magnet embedded rotor having divided cores alternately in the circumferential direction, when the angle between the circumferential ends of the divided core is α [°] and the number of divided cores is n, Molding was performed so as to satisfy the relationship of “α> 360 ° / n”.

  The magnetic flux density between the permanent magnets constituting each magnetic pole in the magnet-embedded rotor is higher on the outer peripheral side than on the inner peripheral side of the rotor core. Therefore, if a gap exists on the outer periphery side of the rotor core between the permanent magnets constituting each magnetic pole, it tends to be a large magnetic resistance for the magnetic circuit of the rotor. In other words, the magnetic resistance of the rotor can be reduced if the gap existing on the outer periphery side of the rotor core between the permanent magnets forming the magnetic poles can be reduced. In this regard, according to the above configuration, when a plurality of divided cores are assembled to form a cylindrical rotor core, adjacent divided cores are easily brought into contact with each other on the outer periphery side of the rotor core. Even in the structure where the boundary line of the core exists, it is difficult to form a gap on the outer periphery side of the rotor core between the permanent magnets. Thereby, since the fall of the magnetic flux amount emitted from a rotor can be suppressed, the output torque of a motor is securable.

  In the magnet-embedded rotor, the divided cores are preferably provided so as to be in contact with the adjacent divided cores on the outer peripheral side of the rotor core and to be separated at the end on the inner peripheral side of the rotor core.

  According to this configuration, since the split cores can be reliably brought into contact with each other on the outer periphery side of the rotor core, it is difficult to further form a gap on the outer periphery side of the rotor core between the permanent magnets forming the magnetic poles. Thereby, since the fall of the amount of magnetic flux emitted from a rotor can further be controlled, the output torque of a motor improves.

The magnet-embedded rotor preferably further includes a cylindrical member that is provided on the outer periphery of the rotor core and fixes the plurality of divided cores in a cylindrical shape.
According to this configuration, after combining a plurality of divided cores into a cylindrical shape, a cylindrical rotor can be easily formed by simply fixing the outer periphery thereof with a cylindrical member.

  For the above-described magnet-embedded rotor manufacturing method, a step of preparing a plurality of divided cores with magnet magnetic members embedded therein and magnetizing the magnet magnetic members to form the permanent magnet After performing every core, it is preferable to form the rotor core by combining a plurality of divided cores that have undergone the magnetizing step into a cylindrical shape.

  If magnetization is performed for each of the plurality of divided cores as in this manufacturing method, a magnetizing device can be disposed on both end surfaces in the circumferential direction and on the inner peripheral surface side of the divided cores. Can pass through. Thereby, since it becomes easy to magnetize the part located in the rotor core inner peripheral side of the magnetic member for magnets, the magnetic flux emitted from a rotor can be increased. As a result, the output torque of the motor can be increased.

  In the magnet-embedded rotor, the magnetizing yoke includes a magnetizing yoke that covers both the circumferential end surfaces of the split core and the inner peripheral surface thereof with a magnetizing magnetic member, and covers the outer peripheral surface of the split core. It is preferable to magnetize the magnet magnetic member based on energization of a coil wound around the magnetizing yoke.

  According to this manufacturing method, the part located in the rotor core inner peripheral side of the magnetic member for magnets can be magnetized exactly.

  According to such a magnet-embedded rotor and a manufacturing method thereof, the output torque of the motor can be ensured while the rotor core is constituted by a plurality of divided cores.

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 expanded sectional structure of the area | region A of FIG. The top view which shows the planar structure of the split core which comprises the rotor core about the magnet embedded type rotor of embodiment. (A) is sectional drawing which shows the process of magnetizing the magnetic member for magnets embedded in the division | segmentation core about the manufacturing method of the magnet embedded type rotor of embodiment. (B) is a top view which shows the process of adhering a cylindrical member to the outer periphery of four division | segmentation cores.

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 FIG.
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 periphery of 3.

  The stator 2 has a structure in which a plurality of electromagnetic steel plates are laminated in the axial direction. Six 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.

  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, and four substantially U-shaped permanent magnets 42 embedded in the rotor core 40.

  The rotor core 40 is configured such that a cross section in a direction orthogonal to the axial direction is divided at equal angular intervals by four divided cores 41 having a substantially fan shape. Each split core 41 is formed with a substantially U-shaped magnet insertion hole 43 into which the permanent magnet 42 is inserted so as to penetrate in the axial direction. Each divided core 41 has a magnetic pole of either an N pole or an S pole on the outer peripheral side by a permanent magnet 42 inserted into the magnet insertion hole 43. The rotor core 40 has a four-pole structure in which split cores 41 having N poles on the outer peripheral side and split cores 41 having S poles on the outer peripheral side are alternately arranged in the circumferential direction.

  A cylindrical member 44 is shrink-fitted around the outer periphery of the rotor core 40, and the four divided cores 41 are fixed in a cylindrical combination by the cylindrical member 44. Further, as shown in FIG. 2 which is an enlarged view of the region A surrounded by the one-dot chain line in the figure, the adjacent two split cores 41 are in contact with the outer peripheral side of the rotor core 40 and the inner peripheral side of the rotor core 40 Are provided so as to be separated from each other at the end. The cylindrical member 44 is made of a nonmagnetic metal material such as SUS in order to prevent leakage of magnetic flux.

  In the motor configured as described above, when a three-phase excitation 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 the permanent magnet 42 inside the rotor 4 based on this rotating magnetic field, and the output shaft 3 rotates.

Next, the operation of the rotor 4 of this embodiment will be described.
As shown in FIG. 2, the magnetic flux density between the two permanent magnets 42 arranged in the circumferential direction in the rotor 4 is higher on the outer peripheral side than on the inner peripheral side of the rotor core 40. Therefore, if there is a gap on the outer periphery side of the rotor core between the two permanent magnets 42 arranged in the circumferential direction, it tends to be a large magnetic resistance for the magnetic circuit of the rotor 4. In other words, the magnetic resistance of the rotor 4 can be reduced if the gap existing on the outer periphery side of the rotor core between the two permanent magnets 42 arranged in the circumferential direction can be reduced.

  In this respect, in the present embodiment, since the adjacent divided cores 41 are in close contact with each other on the outer periphery side of the rotor core, even if the boundary line of the divided core 41 exists between the two permanent magnets 42, the two permanent magnets It becomes difficult to form a gap on the outer periphery side of the rotor core between 42. Thereby, since the fall of the amount of magnetic flux emitted from the rotor 4 can be suppressed, the output torque of a motor is securable.

  Next, a method for manufacturing the rotor 4 will be described together with its operation. First, the shape of the split core 41 will be described in detail with reference to FIG. In FIG. 3, the central axis of the rotor core 40 is indicated by O, the outer diameter of the rotor core 40 is indicated by D, and the inner diameter of the rotor core 40 is indicated by d. A fan-shaped outer shape centered on the central axis O of the rotor 4 with a central angle of 90 ° and an outer diameter of D is indicated by a two-dot chain line.

  As shown in FIG. 3, the split core 41 has the following equations (1), (2), where L1 is the outer arc-side arc linear distance, L2 is the inner-arc linear distance, and p is the number of poles of the rotor 4. It has a shape satisfying.

L1> 2 × D / 2 × sin (360 ° / (2 × p)) (1)
L2 <2 × d / 2 × sin (360 ° / (2 × p)) (2)
Here, in this embodiment, since the number of poles of the rotor 4 is 4, the split core 41 has a shape that satisfies the following expressions (3) and (4).

L1> D × √2 (3)
L2 <d × √2 (4)
In other words, the split core 41 has a shape that satisfies the following expression (5), where α “°” is an angle formed by both circumferential end surfaces, and n is the number of the split cores 41 constituting the rotor 4. ing.

α> 360 ° / n (5)
Here, in this embodiment, since the number of the split cores 41 constituting the rotor 4 is four, the split cores 41 have a shape that satisfies the following expression (6).

α> 90 ° (6)
Next, a method for manufacturing the rotor 4 will be described with reference to FIGS.
When manufacturing the rotor 4, first, four divided cores 41 having a shape as shown in FIG. 3 are formed, and the magnet magnetic member 45 before magnetizing is embedded in the magnet insertion holes 43. As the magnet magnetic member 45, for example, a bond magnet or a sintered magnet is used.

  Subsequently, the magnet magnetic member 45 is magnetized for each divided core 41 using the magnetizing device 5 as shown in FIG. The magnetizing device 5 includes a pedestal 50 on which the split core 41 is placed, and a magnetizing yoke 52 around which a coil 51 is wound.

  The pedestal 50 is made of a magnetic member such as iron. In the present embodiment, the pedestal 50 is a magnetic member for magnetization. On the upper surface of the pedestal 50, recesses 50 a that can cover both end surfaces in the circumferential direction of the split core 41 and the inner peripheral surface thereof are formed.

  And when magnetizing the magnetic member 45 for magnets, as shown in the figure, after placing the split core 41 in the recess 50a of the pedestal 50, the magnetized yoke so as to cover the outer peripheral surface of the split core 41 52 is arranged. When the coil 51 is energized in this state, the magnetic flux generated from the magnetized yoke 52 passes from the outer peripheral surface of the split core 41 through the circumferential end surfaces and the inner peripheral surface as indicated by the arrows in the figure, and the pedestal. The magnet magnetic member 45 is magnetized. By performing such a magnetization process for each of the four divided cores 41, the molding of the four divided cores 41 with the permanent magnets 42 embedded therein is completed.

  Next, as shown in FIG. 4B, the four divided cores 41 are arranged in an annular shape while contacting the outer peripheral ends of both circumferential end surfaces thereof. The cylindrical member 44 is fixed to the outer periphery of the four divided cores 41 by shrink-fitting the cylindrical member 44 to the outer periphery of the four divided cores 41.

  Specifically, the cylindrical member 44 is heated and expanded in advance, and the inner diameter thereof is made larger than the outer diameters of the four divided cores 41 arranged in a cylindrical shape. Then, the heated and expanded cylindrical member 44 is fitted on the outer periphery of the four divided cores 41 arranged in a cylindrical shape. Thereafter, when the diameter of the cylindrical member 44 is reduced by natural cooling as indicated by an arrow in the drawing, the cylindrical member 44 presses the outer peripheral surface of each divided core 41 toward the center in the process. Thereby, each opposing surface of the adjacent division | segmentation core 41 closely_contact | adheres from a rotor core outer peripheral side. When the cooling of the cylindrical member 44 is completed, the cylindrical member 44 is fixed to the outer periphery of the four divided cores 41, and the cylindrical rotor 4 is completed.

According to such a manufacturing method, the rotor 4 shown in FIGS. 1 and 2 can be easily manufactured.
On the other hand, in a conventional rotor, when magnetizing an embedded magnetic member for a magnet, a magnetizing device is disposed outside the outer peripheral surface of the rotor, and the magnetic member for a magnet is magnetized by a magnetic flux generated therefrom. It is used. However, in the case of such a magnetizing method, it is difficult to pass a sufficient magnetic flux on the inner peripheral side of the rotor, and it is difficult to magnetize a portion located on the inner peripheral side of the rotor core of the magnet magnetic member. .

  In this regard, if the manufacturing method of performing magnetization for each divided core 41 as shown in FIG. 4A is employed, the pedestal 50 is arranged so as to cover both circumferential end surfaces and the inner peripheral surface of the divided core 41. Therefore, a sufficient magnetic flux can be passed through the inner peripheral side of the split core 41. This makes it easy to magnetize the portion of the magnet magnetic member 45 located on the inner periphery side of the rotor core, so that the magnetic flux generated from the rotor 4 increases as compared with the case where the conventional magnetizing method is used. As a result, the output torque of the motor can be increased.

As described above, according to the embedded magnet rotor 4 and the manufacturing method thereof of the present embodiment, the following effects can be obtained.
(1) Each divided core 41 constituting the rotor core 40 is provided in contact with the adjacent divided core 41 on the outer periphery side of the rotor core and separated from the end portion on the inner periphery side of the rotor core. As a result, even if the boundary line of the split core 41 exists between the two permanent magnets 42 constituting each magnetic pole in the rotor 4, it is possible to suppress a decrease in the amount of magnetic flux emitted from the rotor 4. Torque can be secured.

  (2) The split core 41 is molded so as to satisfy the above formulas (1) and (2) or so as to satisfy the above formula (5). Thereby, the structure which makes the adjacent division | segmentation core 41 contact on the rotor core outer peripheral side, and is spaced apart on the rotor core inner peripheral side is easily realizable.

  (3) The outer periphery of the rotor core 40 is provided with a cylindrical member 44 that fixes the four divided cores 41 in a cylindrical shape. Thereby, after combining the four split cores 41 in a cylindrical shape, the cylindrical rotor 4 can be easily formed simply by fixing the outer periphery thereof with the cylindrical member 44.

  (4) When the rotor 4 is manufactured, four divided cores 41 in which the magnet magnetic member 45 is embedded are prepared, and the magnetizing process of magnetizing the magnet magnetic member 45 to make the permanent magnet 42 is divided into four. The determination was made for each core 41. Then, the rotor 4 is formed by combining the four divided cores 41 that have undergone the magnetizing step into a cylindrical shape. Thereby, compared with the case where the conventional magnetization method is used, since the magnetic flux emitted from the rotor 4 increases, the output torque of the motor can be increased. In addition, miniaturization of the motor can be expected.

  (5) In the magnetizing step, the both ends in the circumferential direction of the split core 41 and the inner peripheral surface thereof are covered with the pedestal 50 made of a magnetic member, and the magnetized yoke 52 is disposed so as to cover the outer peripheral surface of the split core 41. The magnet magnetic member 45 inside the split core 41 is magnetized based on energization of the coil 51 wound around the magnetizing yoke 52. Thereby, the part located in the rotor core inner peripheral side of the magnetic member 45 for magnets can be magnetized correctly.

In addition, the said embodiment can also be implemented with the following forms which changed this suitably.
In the above embodiment, the U-shaped permanent magnet 42 is embedded in the split core 41. Alternatively, for example, a V-shaped permanent magnet or a U-shaped permanent magnet may be embedded in the split core 41. Good. Further, a plurality of permanent magnets may be embedded in one divided core 41, and the N pole and the S pole may be formed on the outer periphery of the divided core by the plurality of permanent magnets.

  In the above embodiment, the method illustrated in FIG. 4A is adopted as the magnetization method, but the magnetization method may be appropriately changed depending on the shape of the permanent magnet embedded in the split core 41. Moreover, you may change the shape of the magnetizing apparatus 5 suitably with the change of the magnetization method. In short, what is necessary is just to magnetize every division | segmentation core 41 in the case of manufacture of the rotor 4. FIG.

  In the above embodiment, the split core 41 is fixed in a cylindrical shape by shrink fitting the cylindrical member 44 on the outer periphery of the rotor core 40. However, the fixing method of the split core 41 is not limited to shrink fit. For example, the four divided cores 41 may be fixed by press-fitting a cylindrical member 44 around the outer periphery of the rotor core 40. Further, for example, the four divided cores 41 may be fixed by molding the outer periphery of the four divided cores 41 with a resin member. In this case, the resin member provided on the outer periphery of the four divided cores 41 is a cylindrical member. In short, the cylindrical member may be any member provided on the outer periphery of the rotor core 40 and fixing the four divided cores in a cylindrical shape.

  In the above embodiment, the number of magnetic poles of the rotor 4 is four. However, the number of poles of the rotor 4 may be appropriately changed to, for example, two or eight. Further, the number of split cores 41 constituting the rotor core 40, the number of permanent magnets 42, the shape of the stator 2 and the like may be changed as appropriate.

  In the above embodiment, the shape shown in FIG. 3 is adopted as the shape of the split core 41. However, each split core 41 is in contact with the adjacent split core on the outer periphery side of the rotor core and the end portion on the inner periphery side of the rotor core. If it can arrange | position so that it may space apart, the shape of the division | segmentation core 41 can be changed suitably.

  DESCRIPTION OF SYMBOLS 4 ... Magnet embedded rotor, 40 ... Rotor core, 41 ... Split core, 42 ... Permanent magnet, 44 ... Cylindrical member, 45 ... Magnetic member for magnets, 51 ... Coil, 52 ... Magnetizing yoke.

Claims (5)

A cylindrical rotor core, and a plurality of permanent magnets embedded in the rotor core,
The rotor core is a magnet-embedded rotor in which split cores having N poles on the outer peripheral side and split cores having S poles on the outer peripheral side are alternately provided in the circumferential direction.
The split core has the following formula, where α [°] is an angle formed by both circumferential end surfaces, and n is the number of split cores:
α> 360 ° / n
A magnet-embedded rotor characterized by being formed so as to satisfy the following relationship. The embedded magnet rotor according to claim 1,
The embedded core rotor, wherein the split core is provided so as to contact an adjacent split core on the outer peripheral side of the rotor core and to be separated at an end on the inner peripheral side of the rotor core. The embedded magnet rotor according to claim 1 or 2,
A magnet-embedded rotor, further comprising a cylindrical member that is provided on an outer periphery of the rotor core and fixes the plurality of divided cores in a cylindrical shape. In the manufacturing method of the magnet embedded rotor according to any one of claims 1 to 3,
Preparing a plurality of split cores embedded with magnet magnetic members, and magnetizing the magnet magnetic members to form the permanent magnets for each of the plurality of split cores; The rotor core is formed by combining a plurality of split cores that have undergone the above process into a cylindrical shape. In the manufacturing method of the magnet embedded rotor according to claim 4,
In the magnetizing step, both end surfaces in the circumferential direction of the split core and the inner peripheral surface thereof are covered with a magnetizing magnetic member, and the magnetized yoke is disposed so as to cover the outer peripheral surface of the split core, and then the magnetized yoke A magnet-embedded rotor manufacturing method characterized by magnetizing the magnet magnetic member based on energization of a coil wound around the magnet.