JP2007228771A - Permanent magnet type motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a permanent magnet type motor, capable of forming skew on a rotor in which permanent magnets are embedded and preferably attaining low vibration noise by restraining cogging torque. <P>SOLUTION: This permanent magnet embedded rotor is formed with embedded hole portions 13 for disposing the permanent magnets 12 at fixed intervals, a rotor iron core 11, laminated by aligning the embedded hole portions 13 in an axial direction, and the permanent magnets 12, of which the outer periphery is of an arc shape, to be inserted in the respective embedded hole portions 13 of the rotor iron core 11. Two poles of the permanent magnets 12 are polarized in a substantially outer periphery direction, being embedded in the rotor iron core, and the adjacent embedded portions in the same pole are skew-polarized. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a structure of a permanent magnet embedded rotor of a permanent magnet type motor in which a sintered magnet is embedded in a rotor core.

  Conventional permanent magnet embedded rotors are generally obtained by laminating rotor core sheets having the same shape having embedded holes in the same direction and embedding a rectangular parallelepiped (flat plate) permanent magnet in the embedded holes. . Hereinafter, a conventional permanent magnet type motor will be described with reference to FIG.

  In FIG. 2, the stator core 27 of the stator 28 has teeth 25 and slots 26, and the slots 26 have a plurality of windings (not shown) to apply a rotating magnetic field to the rotor 20.

  The rotor core 21 is formed by stacking punched electromagnetic steel plates, constitutes a magnetic path of the rotor 20, and holds the permanent magnet 22 in the embedding hole 23. The permanent magnet 22 is alternately magnetized to a plurality of magnetic poles related to the number of poles of the stator 27.

  In the permanent magnet type motor configured as described above, for example, a three-phase winding of U-phase, V-phase, and W-phase is formed on the stator 28, and a rotating magnetic field is generated in the stator core 27 when energized with a predetermined phase difference. Then, a torque is generated between the magnetized rotor 20 and the permanent magnet 22 so that the rotor 20 rotates at a synchronous speed.

Also, in order to reduce noise vibration, the shape of the permanent magnet embedding hole is the same, and the shape of the elongated hole provided so as to be in contact with the end surface of the permanent magnet, the end portion of the positive electrode surface, or the end portion of the negative electrode surface Has been proposed (see, for example, Patent Document 1).
JP 2000-69695 A

  In a rotor embedded with a flat permanent magnet, the permeance coefficient (Bd / Hd) is different in each part of the magnetic pole of the permanent magnet, and the magnetomotive force of the magnet becomes non-uniform in the rotational direction. Cogging torque is generated in the rotor in relation to the arc length.

  In general, skew is often provided as a method of reducing cogging torque. However, in the conventional permanent magnet embedded rotor, it is extremely difficult to obtain an effective skew for suppressing the cogging torque.

  In particular, when embedding a flat sintered magnet in the rotor core, it is impossible to provide a skew other than enlarging the embedding hole. When the embedding hole is enlarged, the gap between the magnetic pole surface of the permanent magnet and the rotor core Since an air gap is generated, the permeance coefficient is lowered and the efficiency is lowered. Further, when one pole is magnetized to one flat plate-shaped sintered magnet, it is impossible to magnetize with skew.

  SUMMARY OF THE INVENTION An object of the present invention is to solve the conventional problems, and to provide a permanent magnet type motor that can skew magnetize a permanent magnet embedded rotor and suppress cogging torque and has good vibration noise at low cost. To do.

  In order to solve the above problems, the present invention provides a permanent magnet type motor having a stator having a multi-phase winding in a stator core and a permanent magnet embedded rotor disposed inside the stator core via a gap. The rotor has embedded hole portions for arranging permanent magnets at equal intervals, a rotor core in which the embedded hole portions are aligned in the same axial direction, and an outer periphery to be inserted into each embedded hole portion of the rotor core. An arc-shaped permanent magnet, and the permanent magnet is magnetized in two poles in a substantially outer circumferential direction in a state of being embedded in the rotor iron core, and between adjacent embedded holes is the same pole and skew magnetized. Can be suppressed.

  According to the permanent magnet type motor of the present invention, since the outer periphery of the rotor core is circular even if the buried hole portions are aligned in the axial direction, one permanent magnet can be magnetized in two poles and skewed. Cogging torque generated between the stator core and the stator core can be suppressed.

  In addition, since the cross-sectional shape can be changed to a kamaboko shape, the permanent magnet can be easily processed and can be obtained at low cost. Furthermore, the leakage of magnetic flux between the magnetic poles can be suppressed by setting the outer side of the buried hole to a uniform width comparable to the thickness of the laminated plates.

  In a permanent magnet type motor having a stator having a plurality of phases of windings in a stator core and a permanent magnet embedded rotor disposed inside the stator core via a gap, the permanent magnet embedded rotor arranges the permanent magnets at equal intervals. A rotor iron core having a buried hole portion for stacking the buried hole portions aligned in the axial direction, and a permanent magnet having an arcuate outer periphery to be inserted into each buried hole portion of the rotor core. The outer periphery of the embedded hole is set to have a uniform width equivalent to the thickness of the laminated plate, and the permanent magnet is a flat-bottomed sintered magnet having a flat bottom surface and is embedded in the rotor core in a substantially outer circumferential direction. Two poles are magnetized, and adjacent buried holes are poled and skew magnetized.

  The permanent magnet type motor of Example 1 is the same except that the configuration of the permanent magnet embedded rotor is different from that of the conventional permanent magnet type motor. In Example 1, the permanent magnet embedded rotor of the present invention is the same. A description of the stator having three-phase windings on the 12 stator salient poles will be omitted.

  A significant difference from the configuration of the conventional permanent magnet embedded rotor is that one permanent magnet to be mounted in one embedded hole is two-pole magnetized and skewed.

  Hereinafter, description will be given with reference to the drawings. In FIG. 1, 11 is a rotor iron core, 12 is a permanent magnet, 13 is a buried hole, and 14 is a rotating shaft.

  The rotor core 11 is provided with eight embedded hole portions 13 having an arcuate outer periphery for accommodating the permanent magnets 12 at equal intervals, and a predetermined number of the embedded hole portions 13 are aligned in the axial direction.

  Further, the outer side of the embedded hole 13 of the rotor core 11 is set to have a uniform width equivalent to the thickness of the laminated plate (for example, 0.5 mm), and the press work can be performed between the magnetic poles by magnetizing described later. Magnetic flux leakage can be suppressed.

  On the other hand, the permanent magnet 12 is a segment type rare earth sintered magnet, and can be manufactured at a low cost by making it a round shape with a circular outer periphery and a flat bottom. The center of the inner and outer diameters of the buried hole portion 13 and the permanent magnet 12 may be on the rotation axis and may have the same thickness.

  After the permanent magnets 12 are attached to the respective embedded hole portions 13 and fixed with an adhesive, a skew of θ degrees is applied in the axial direction, and magnetized in the radial direction so as to straddle between the adjacent embedded hole portions 13.

  A part of the magnetic flux of the two-pole magnetized permanent magnet 12 tends to flow from the north pole to the south pole via the outside of the rotor core 11, but as described above, the embedded hole portion of the rotor core 11 The outer side of 13 is set to a uniform width equivalent to the plate thickness, and the leakage of magnetic flux between the magnetic poles can be suppressed.

  Thereafter, the rotary shaft 14 is mounted in the central hole of the rotor iron core 12 to form a permanent magnet embedded rotor.

  In the embodiment, the 8-pole rotor has been described. However, the present invention is not limited to this, and the skew angle θ is determined optimally from the number of magnetic poles and axial dimensions of the stator and the rotor.

  The permanent magnet type motor of the present invention is optimal for high speed and large output, and is useful for servo motors and the like where controllability is important.

The perspective view of the permanent magnet buried type rotor in Example 1 of this invention Sectional view of permanent magnet embedded motor in conventional example

Explanation of symbols

11 Rotor core 12 Permanent magnet 13 Buried hole 14 Rotating shaft

Claims (3)

In a permanent magnet type motor having a stator having a plurality of phases of windings in a stator core and a permanent magnet embedded rotor disposed inside the stator core via a gap, the permanent magnet embedded rotor arranges the permanent magnets at equal intervals. A rotor iron core having a buried hole portion for laminating the buried hole portion in the axial direction, and a permanent magnet having an arcuate outer periphery to be inserted into each buried hole portion of the rotor iron core. Is a permanent magnet motor characterized in that it is magnetized in two poles in a substantially outer circumferential direction in a state of being embedded in a rotor iron core, and between adjacent buried hole portions has the same polarity and skew magnetization. The permanent magnet motor according to claim 1, wherein the permanent magnet is a sintered magnet and has a flat bottom surface. The permanent magnet type motor according to claim 1 or 2, wherein the magnetic flux leakage between the magnetic poles is suppressed by setting the outer side of the embedded hole portion of the rotor core to a uniform width as large as the thickness of the laminated plates.

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