JP2008131853A - Magnet-embedded rotor and manufacturing method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a magnet-embedded rotor capable of improving characteristics in motor, materializing operation under low noise, and keeping rigidity. <P>SOLUTION: The magnet-embedded rotor 1 has a permanent magnet 8 embedded therein. The rotor is equipped with a permanent-magnet mounting portion with the permanent magnet 8 mounted on the outer periphery, a first core 6 serving as the magnetic path of the permanent magnet 8, the permanent magnet 8 in the permanent-magnet mounting portion, an outer-peripheral iron core 7a provided outside the first core 6 and the permanent magnet 8 with relative magnetic permeability smaller than that of the first core 6 and disposed opposite to the magnetic core 8, and an interpolar iron core 7b in between the permanent magnets 8. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a magnet-embedded rotor used for a DC brushless motor or the like and a method for manufacturing the same.

In order to reduce the armature reaction magnetic flux and improve the magnetic flux distribution of the outer peripheral core, to provide a highly efficient permanent magnet motor with less noise and vibration, the rotor core is centered on its axis. Permanent magnet accommodation holes formed in portions corresponding to the sides of the substantially regular polygon, permanent magnets inserted into the permanent magnet accommodation holes, and outer peripheral cores of the permanent magnet accommodation holes, and in the radial direction 4 or more slit holes that are elongated and spaced apart along the permanent magnet receiving hole, and the pitch of the radially outer end of the slit hole is substantially equal, and the pitch of the radially inner end is set to the center of the permanent magnet. A permanent magnet electric motor has been proposed in which the size of the portion is increased and the size is reduced as the distance from the center portion increases.
JP 2005-94968 A

However, the permanent magnet motor described in Patent Document 1 has the following problems.
(1) By providing a plurality of slits in the outer peripheral iron core of the permanent magnet accommodation hole, it is possible to prevent the magnetic flux generated by the permanent magnet inserted into the permanent magnet accommodation hole from being short-circuited in the middle, and the direction in which the magnetic flux easily flows. This is to make the direction difficult to flow, and a torque that makes full use of the characteristics of the permanent magnet can be obtained. However, the provision of a plurality of slits sometimes sacrifices the strength of the rotor.
(2) Since the difference between the magnetic resistance of the magnetic steel sheet portion and the magnetic resistance of the slit portion (= air) is very large, the flow of magnetic flux is too concentrated in a certain direction, resulting in imbalance of the magnetic flux flow and cogging It was a cause of torque and torque ripple.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a magnet-embedded rotor capable of improving motor characteristics, reducing noise, and maintaining strength, and a method of manufacturing the same. And

  An embedded magnet type rotor according to the present invention is a magnet embedded type rotor having a permanent magnet inside, and has a permanent magnet mounting portion for mounting a permanent magnet on the outer periphery, and a first core serving as a magnetic path of the permanent magnet A permanent magnet mounted on the permanent magnet mounting portion; and an outer peripheral iron core portion that is provided outside the first core and the permanent magnet and has a relative permeability smaller than that of the first core and faces the permanent magnet. And a second core constituting the inter-magnetic core between the permanent magnets.

  The magnet-embedded rotor according to the present invention has effects such as securing strength, low vibration / low noise, high efficiency, and low price due to the above configuration.

Embodiment 1 FIG.
1 to 12 show the first embodiment. FIG. 1 is a cross-sectional view of the motor 100, FIG. 2 is a cross-sectional view of the magnet-embedded rotor 1, and FIG. FIG. 4 is an enlarged view of a main part of FIG. 3, and FIG. 5 is a diagram illustrating a magnet embedded rotor 1 composed of a first core 6 and a second core 7. FIG. 6 is a diagram showing the torque of the motor 100 calculated by magnetic field analysis, FIG. 7 is a plan view of the first core 6, and FIG. 8 is a modified example of the magnet embedded rotor 1. FIG. 9 is a plan view of a modified example of the first core 6, FIG. 10 is a sectional view of a modified example of the magnet embedded rotor 1, and FIG. 11 is a modified example of the magnet embedded rotor 1. FIG. 12 is a sectional view showing a modification of the magnet embedded rotor 1.

  The motor 100 in FIG. 1 is a DC brushless motor. The use of the motor 100 is, for example, a blower. The motor 100 includes a magnet-embedded rotor 1 with a shaft 12 fitted at the center, a stator 2, a frame 3, bearings, brackets, and the like (not shown). The stator 2 is formed by caulking or the like by laminating a predetermined number of electromagnetic steel plates (thickness 0.35 to 0.5 mm) punched into a predetermined shape. The stator 2 is configured by a core back 2c whose outer shape is substantially ring-shaped and whose outer peripheral portion is annular. Six teeth 2a extend radially inward from the annular core back 2c. Between the teeth 2a, there is a slot 2b having an opening 5 on the inner peripheral side, and the number of slots 2b is six, which is the same number as the teeth 2a. A coil 4 is wound around each tooth 2a by, for example, a concentrated winding method using the space of the slots 2b on both sides. In addition to the concentrated winding method, there is also a distributed winding method. The coil 4 is usually provided with a three-phase winding.

  The magnet-embedded rotor 1 is inserted into the stator 2 through the gap 11. In the magnet-embedded rotor 1, four permanent magnets 8 are provided in the circumferential direction in the vicinity of the outer peripheral portion. Therefore, the number of poles of the motor 100 is four. However, this is an example and is not limited to four poles. The shaft 12 is fitted in the center of the magnet embedded rotor 1. A bearing (generally a ball bearing) (not shown) is attached to the shaft 12.

  For example, a metal frame 3 is fitted on the outer periphery of the stator 2. Furthermore, brackets (not shown) are attached to both ends of the frame 3 to complete the motor 100.

  The present embodiment is characterized by the structure of the magnet embedded rotor 1. The structure of the magnet embedded rotor 1 will be described with reference to FIG. A magnet embedded rotor 1 shown in FIG. 2 is provided with a substantially cross-shaped first core 6 through which the main magnetic flux of the permanent magnet 8 passes, and an outer peripheral iron core portion 7a. And a core core portion 7b between the magnetic poles, and is divided into a second core 7 that forms the outer peripheral portion of the magnet-embedded rotor 1.

  The first core 6 is, for example, a laminate of electromagnetic steel sheets having a plate thickness of 0.35 to 0.5 mm, and has a high relative permeability (about several thousand). On the other hand, the second core 7 is made of a material having a small relative permeability (several tens to hundreds). For example, a material obtained by kneading a soft magnetic powder (for example, iron powder) with a resin (a thermoplastic resin, for example, nylon).

  The substantially cross-shaped first core 6 has a shape as shown in FIG. There are planar permanent magnet mounting portions 6f for mounting the permanent magnets 8 at four locations on the outer periphery, and permanent magnet positioning projections 6d extending in the axial direction are formed at both ends of the permanent magnet mounting portion 6f. Further, a shaft hole 6b is formed at the center. Further, between the magnetic poles, an arc shape that is recessed inward along the flow of the main magnetic flux from the permanent magnet 8 is formed. This improves the flow of the kneaded material in the mold at the time of injection molding using the material obtained by kneading the resin with the soft magnetic powder.

  Four permanent magnets 8 are mounted on the permanent magnet mounting portion 6 f of the first core 6. In this case, if the permanent magnet 8 is magnetized, the first core 6 can be easily mounted on the permanent magnet mounting portion 6f. In FIG. 2, the arrow indicates the magnetic flux generated by the permanent magnet 8, and this magnetic flux passes smoothly through the first core 6 as shown in the figure.

  In the second core 7, a plurality of slits 10 are formed in the outer peripheral iron core portion 7 a facing the permanent magnet 8. In the slit 10, there is a slit forming component 10a for forming the slit 10. The slit forming component 10a may be anything as long as it is non-magnetic, but for example, ABS resin is used. The slit 10 is not a cavity but a nonmagnetic material is inserted. The number of slits 10 per pole is not particularly limited, but the slit 10 portion and the other portions may have an area of about half of the cross section.

The process for manufacturing the magnet-embedded rotor 1 is, for example, as follows.
(1) First, a predetermined number of electromagnetic steel sheets punched into a predetermined shape are laminated to form a substantially cross-shaped first core 6.
(2) The permanent magnet 8 to be mounted on the permanent magnet mounting portion 6f of the first core 6 is prepared. At this time, it is convenient to magnetize the permanent magnet 8.
(3) A first core is formed on a resin molding die in which a slit forming component 10a using a nonmagnetic material (for example, ABS resin) having a higher melting point than a material obtained by kneading a resin with soft magnetic powder for injection molding is set. 6 and the permanent magnet 8 is mounted on the permanent magnet mounting portion 6f of the first core 6 using, for example, magnetic force.
(4) A material obtained by kneading a resin in soft magnetic powder is injected and molded.
In this way, the embedded magnet rotor 1 in which the outer peripheral portion is the second core 7 having a small relative permeability and the first core 6 having a large relative permeability is disposed inside the second core 7 is completed. The slit forming component 10a set in the resin molding die remains in the slit 10 when the magnet-embedded rotor 1 is taken out of the die. Therefore, it is necessary to use a nonmagnetic material for the slit forming component 10a.

  In the magnet-embedded rotor 1 shown in FIG. 2, the main magnetic flux generated by the permanent magnet 8 passes through the first core 6 having a large relative permeability mainly as indicated by an arrow in the figure. When the entire core of the magnet-embedded rotor 1 is an electromagnetic steel plate, magnetic flux leaks at the end of the permanent magnet 8 or the like. As a result, the main magnetic flux may decrease and the motor characteristics may deteriorate.

  Further, if the entire core of the magnet-embedded rotor 1 is a magnetic steel plate and the slits 10 are provided, the magnetic unbalance between the poles increases, so the cogging torque and torque ripple increase, causing vibration and noise. It becomes.

  Therefore, as shown in FIG. 2, a material having lower magnetic properties (lower magnetic permeability) than the first core 6 (for example, a material obtained by kneading a resin in soft magnetic powder) is applied to the second core 7 between the magnetic poles. By using and forming the plurality of slits 10 in the outer peripheral core portion 7a, leakage of magnetic flux to the end portion of the permanent magnet 8 can be suppressed, and magnetic flux unbalance can be eliminated.

  Here, when the embedded magnet rotor 1 is configured by only the first core 6, and the embedded magnet rotor 1 is configured by the first core 6 and the second core 7 as in the present embodiment. Compare the flow of magnetic flux with the configuration.

  FIG. 3 is a diagram showing the flow of magnetic flux when the magnet-embedded rotor 1 is composed of only the first core 6. As shown in the figure, the magnetic flux is short-circuited at both ends of the permanent magnet 8 (FIG. (See also enlarged view 4). Therefore, the main magnetic flux from the pole of the permanent magnet 8 to the pole is insufficient.

  FIG. 5 is a diagram showing the flow of magnetic flux when the magnet-embedded rotor 1 is composed of the first core 6 and the second core 7. With this configuration, the magnetic flux at both ends of the permanent magnet 8 is shown. The short circuit is suppressed, and the main magnetic flux from the pole of the permanent magnet 8 to the pole can be sufficiently passed.

  FIG. 6 shows the result of calculating the torque by the magnetic field analysis of the motor 100 using the magnet-embedded rotor 1 of the present embodiment. For comparison, the torque of a conventional example in which the entire core of the magnet embedded rotor 1 is made of an electromagnetic steel plate and has a slit 10 in the outer peripheral iron core is also shown. As shown in FIG. 6, the motor 100 of the present embodiment has a significantly larger torque and a smaller torque ripple than those of the conventional example. This is because magnetic pole leakage of the permanent magnet 8 is suppressed by forming the inter-magnetic pole core portion 7b of the second core 7 having a small relative permeability between the magnetic poles and providing a plurality of slits 10 in the outer peripheral iron core portion 7a. This is because the magnetic flux density waveform of the air gap becomes a waveform close to a sine wave.

  FIG. 8 is a cross-sectional view showing a modification of the embedded magnet rotor 1, and FIG. 9 is a plan view of a modification of the first core 6. In the magnet-embedded rotor 1 in FIG. 2, the shape of the interpolar portion of the first core 6 is an arc, but may be V-shaped as shown in FIGS. 8 and 9.

  FIG. 10 is a cross-sectional view showing a modification of the magnet embedded rotor 1. As shown in FIG. 10, the slit 10 formed in the outer core portion 7 a of the second core 7 may be inclined obliquely toward the pole center. Thereby, magnetic flux concentrates on the pole center, and torque characteristics are improved.

  FIG. 11 is a cross-sectional view showing a modification of the magnet embedded rotor 1. As shown in FIG. 11, a permanent magnet is obtained by enlarging the end slit 10b located at the circumferential end of the outer core portion 7a in the slit 10 formed in the outer core portion 7a of the second core 7. The short circuit of the magnetic flux in 8 edge part can be suppressed.

  FIG. 12 is a cross-sectional view showing a modification of the magnet embedded rotor 1. As shown in FIG. 12, the outer periphery of the second core 7 may not be cylindrical, and the inter-magnetic core portion 7b may be recessed inward so that the space between the magnetic poles is a space. As a result, the magnetic flux passing between the magnetic poles is further reduced, and the torque characteristics can be improved.

Embodiment 2. FIG.
FIGS. 13 and 14 are diagrams showing the second embodiment, FIG. 13 is a sectional view of the magnet-embedded rotor 1, and FIG. 14 is a plan view showing an example of the first core 6.
In the present embodiment, the gap between the magnetic poles is formed by the second core 7, and the other portions are formed by the first core 6. That is, the first core 6 is configured by laminating a predetermined number of electromagnetic steel plates punched into a predetermined shape. Each electromagnetic steel sheet is substantially cross-shaped, has a plurality of slits 10 in the outer peripheral iron core portion 6a, and has a permanent magnet insertion hole 9 formed therein. The slit 10 is a cavity. At both ends in the circumferential direction of the permanent magnet insertion hole 9, the portion of the magnetic path through which the main magnetic flux passes and the outer peripheral core portion 6a are connected by the thin portion 6c. A shaft hole 6 b is formed at the center of the first core 6. By configuring the first core 6 in this way, the core having the slit 10, the permanent magnet insertion hole 9, and the like can be integrally formed.

  When the first core 6 shown in FIG. 14 is used and the second core 7 is resin-molded using a material obtained by kneading a resin with soft magnetic powder between the magnetic poles, the magnet-embedded rotor 1 shown in FIG. 13 is obtained. . If the 1st core 6 is comprised in this way, the insertion position of the permanent magnet 8 will be decided previously. Further, the resin molding die has a simple configuration.

A manufacturing process of the embedded magnet rotor 1 shown in FIG. 13 will be described below.
(1) First, a predetermined number of electromagnetic steel plates punched so as to have a plurality of slits 10 in the outer peripheral iron core portion 6a and have permanent magnet insertion holes 9 inside thereof are laminated to form a substantially cross-shaped first core. Make 6.
(2) A permanent magnet 8 to be inserted into the permanent magnet insertion hole 9 of the first core 6 is prepared. At this time, the permanent magnet 8 need not be magnetized.
(3) The first core 6 is disposed in the resin molding die, and the permanent magnet 8 is inserted into the permanent magnet insertion hole 9 of the first core 6.
(4) A material obtained by kneading a resin in soft magnetic powder is injected and molded.

  Thus, by using the first core 6 shown in FIG. 14, it is not necessary to set the slit forming component 10a in the resin molding die, and the resin molding die is simplified. Further, since the permanent magnet insertion hole 9 is formed in the first core 6, it is not necessary to magnetize the permanent magnet 8, and positioning of the permanent magnet 8 is easy.

FIG. 3 shows the first embodiment and is a cross-sectional view of the motor 100. FIG. 3 shows the first embodiment, and is a cross-sectional view of the magnet-embedded rotor 1. FIG. 5 shows the first embodiment, and shows the flow of magnetic flux when the magnet-embedded rotor 1 is composed of only a first core 6. FIG. 4 shows the first embodiment and is an enlarged view of a main part of FIG. 3. FIG. 3 shows the first embodiment, and shows the flow of magnetic flux when the magnet-embedded rotor 1 is composed of a first core 6 and a second core 7. FIG. 5 shows the torque of the motor 100 calculated by magnetic field analysis, showing the first embodiment. FIG. 5 shows the first embodiment and is a plan view of the first core 6. FIG. 5 shows the first embodiment, and is a cross-sectional view showing a modification of the magnet embedded rotor 1. FIG. 5 shows the first embodiment, and is a plan view of a modified example of the first core 6. FIG. 5 shows the first embodiment, and is a cross-sectional view showing a modification of the magnet embedded rotor 1. FIG. 5 shows the first embodiment, and is a cross-sectional view showing a modification of the magnet embedded rotor 1. FIG. 5 is a diagram illustrating the first embodiment and is a cross-sectional view illustrating a modification of the magnet-embedded rotor 1. FIG. 5 shows the second embodiment and is a cross-sectional view of the magnet-embedded rotor 1. FIG. 5 shows the second embodiment and is a plan view showing an example of a first core 6.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Magnet embedded rotor, 2 stator, 2a teeth, 2b slot, 2c core back, 3 frame, 4 coil, 5 opening part, 6 1st core, 6a outer periphery iron core part, 6b axial hole, 6c thin part, 6d Permanent magnet positioning projection, 6f Permanent magnet mounting part, 7 Second core, 7a Outer iron core part, 7b Inter-magnetic core part, 8 Permanent magnet, 9 Permanent magnet insertion hole, 10 slit, 10a Slit forming part, 11 Air gap, 12 Shaft, 100 motor.

Claims (14)

In a magnet embedded rotor having a permanent magnet inside,
A first core that has a permanent magnet mounting portion for mounting a permanent magnet on an outer periphery, and serves as a magnetic path of the permanent magnet;
A permanent magnet mounted on the permanent magnet mounting portion;
Provided outside the first core and the permanent magnet, the relative permeability is smaller than the relative permeability of the first core, and the magnetic pole between the permanent magnets and the outer peripheral iron core facing the permanent magnet A magnet-embedded rotor comprising a second core that constitutes an intermediate iron core.   The embedded magnet type rotor according to claim 1, wherein the second core has a plurality of slits in the outer peripheral core portion.   3. The embedded magnet rotor according to claim 1, wherein the permanent magnet mounting portion includes permanent magnet positioning protrusions at both ends.   4. The magnet-embedded rotor according to claim 1, wherein a portion between the magnetic poles between the permanent magnet mounting portions of the first core has an arc shape recessed inward. 5.   5. The magnet-embedded rotor according to claim 1, wherein a portion between the magnetic poles between the permanent magnet mounting portions of the first core has a V shape recessed inward.   The embedded magnet type rotor according to any one of claims 2 to 5, wherein a slit provided in the outer peripheral core portion of the second core is inclined obliquely toward the pole center.   7. The slits provided in the outer peripheral core portion of the second core, wherein an end slit located at a circumferential end of the outer peripheral core portion is made larger than other slits. The magnet embedded rotor according to any one of the above. In the manufacturing method of a magnet embedded rotor having a permanent magnet inside,
Forming a first core having a permanent magnet mounting portion by laminating a predetermined number of electromagnetic steel sheets punched into a predetermined shape;
Forming a permanent magnet to be mounted on the permanent magnet mounting portion of the first core;
The first core is disposed on a resin molding die, and the permanent magnet is mounted on the permanent magnet mounting portion of the first core,
A method of manufacturing a magnet-embedded rotor, wherein a material obtained by kneading a resin in soft magnetic powder is injected into the resin molding die, and a second core is integrally formed with the first core.   The kneaded material is injected in a state where a slit forming component using a nonmagnetic material having a melting point higher than that of a material obtained by kneading resin in soft magnetic powder for injection molding is set in the mold for resin molding. A method of manufacturing a magnet-embedded rotor according to claim 8.   The method for manufacturing a magnet-embedded rotor according to claim 8 or 9, wherein a permanent magnet to be mounted on the permanent magnet mounting portion of the first core is previously magnetized. In a magnet embedded rotor having a permanent magnet inside,
A first core that has an outer peripheral iron core portion and a permanent magnet insertion hole into which the permanent magnet is inserted inside the outer peripheral iron core portion, and serves as a magnetic path of the permanent magnet;
A permanent magnet inserted into the permanent magnet insertion hole;
An embedded magnet rotor, comprising: a second core formed between the magnetic poles of the first core and having a relative permeability smaller than that of the first core.   The embedded magnet-type rotor according to claim 11, wherein the first core has a plurality of slits in the outer peripheral core portion.   The first core is formed by laminating electromagnetic steel plates, and the second core is formed by injection molding a material obtained by kneading a resin in soft magnetic powder. The described magnet-embedded rotor. In the manufacturing method of a magnet embedded rotor having a permanent magnet inside,
Forming a first core having permanent magnet insertion holes by laminating a predetermined number of electromagnetic steel sheets punched into a predetermined shape;
Forming a permanent magnet to be inserted into the permanent magnet insertion hole of the first core;
Placing the first core in a resin molding die, inserting the permanent magnet into the permanent magnet insertion hole of the first core,
A method of manufacturing a magnet-embedded rotor, wherein a material obtained by kneading a resin in soft magnetic powder is injected into the resin molding die, and a second core is integrally formed with the first core.

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