JP2014220879A - Permanent magnet rotary electric machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress a reduction in torque of a permanent magnet rotary electric machine to suppress the demagnetization of a permanent magnet.SOLUTION: A permanent magnet rotary electric machine includes a stator core, a stator that has a winding wound around a teeth part of the stator core, and a rotor that is arranged rotatably with respect to the stator via a gap and has a plurality of rotor cores and a plurality of permanent magnets having a different polarity from each other arranged alternately along the circumference direction, where the permanent magnets are divided into plurality in a direction opposite to the stator.

Description

The present invention relates to a permanent magnet rotating electrical machine.

  Among permanent magnet rotating electrical machines, the cross-sectional shape of the permanent magnet is longer in the radial direction than the circumferential direction, and the permanent magnet is magnetized in the circumferential direction, and the magnets are arranged alternately so that the magnetizing directions of adjacent magnets face each other. Things are known. While this type of motor can increase the output torque, there is a problem that the permanent magnet tends to demagnetize.

Therefore, Patent Document 1 discloses that local demagnetization of a permanent magnet is prevented by providing a magnetic resistance.

JP2011-217601A

  In Patent Document 1, a portion that functions as a magnetic resistance and a magnetic barrier is provided in a slot corresponding to a receiving portion of a permanent magnet. Since the portion that functions as the magnetic resistance and the magnetic barrier is not occupied by the permanent magnet, the field magnetic flux is reduced correspondingly, resulting in a reduction in torque.

The present invention has been made paying attention to the above-described problem, and an object of the present invention is to provide a permanent magnet rotating electrical machine that suppresses a decrease in torque and suppresses demagnetization of the permanent magnet.

In order to solve the above problems, for example, the configuration described in the claims is adopted. The present application includes a plurality of means for solving the above-described problem. To give an example, a stator having a stator core and a winding wound around a tooth portion of the stator core, and the fixing Permanent magnet rotation with a rotor core and a rotor in which a plurality of permanent magnets having different polarities are alternately arranged in the circumferential direction, arranged rotatably with respect to the rotor through a gap In the electric machine, the permanent magnet is divided into a plurality of parts in a direction facing the stator.

ADVANTAGE OF THE INVENTION According to this invention, the fall of the torque of a permanent magnet rotary electric machine can be suppressed, and the demagnetization of a permanent magnet can be suppressed. As a result, the permanent magnet rotating electric machine can be reduced in size.

1/4 sectional view of the permanent magnet rotating electric machine of Example 1 of the present invention 1/4 sectional view of a conventional permanent magnet rotating electrical machine 1/4 sectional view of the permanent magnet rotating electric machine of Example 2 of the present invention 1/4 sectional view of the permanent magnet rotating electrical machine of Example 3 of the present invention 1/4 sectional view of the permanent magnet rotating electric machine of Example 4 of the present invention 1/4 sectional view of the permanent magnet rotating electric machine of Example 5 of the present invention 1/4 sectional view of the permanent magnet rotating electric machine of Example 6 of the present invention 1/4 sectional view of the permanent magnet rotating electric machine of Example 7 of the present invention Cross section of permanent magnet rotating electrical machine

  Embodiments will be described below with reference to the drawings.

  First, the configuration of the rotating electrical machine common to the embodiments of the present invention will be described. FIG. 9 is a cross-sectional view along the axial direction of the permanent magnet rotating electric machine (direction parallel to the rotation axis of the rotor). The permanent magnet rotating electrical machine is composed of a stator 1 and a rotor 2 facing radially inward, and an air gap exists between the two. The stator 1 is fixed to the housing 110 and includes a concentrated winding stator winding 13. The rotor 2 has a rotor core 21 in which a plurality of electromagnetic steel plates are laminated. A nonmagnetic material 23 is disposed on the radially inner side of the rotor core 21 and a shaft 120 is disposed on the inner side. . The shaft 120 is rotatably supported by a bearing 140 fixed to the housing 110 or the flange 130.

  Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. In the present embodiment, as an example of a combination of two rotor magnetic poles with respect to three stator teeth, a case where there are 12 stator teeth and eight rotor magnetic poles will be described.

  FIG. 1 is a ¼ cross-sectional view along a plane perpendicular to the axial direction of the permanent magnet rotating electric machine according to the first embodiment of the present invention. The permanent magnet rotating electrical machine is composed of a stator 1 and a rotor 2 facing radially inward, and an air gap exists between the two. The stator 1 is composed of a stator core 11 in which a plurality of electromagnetic steel plates are laminated. The stator core 11 has a plurality of stator teeth 12, and a stator winding 13 is wound around each tooth in a concentrated manner. It has been turned. In the rotor 2, a rotor core 21 in which a plurality of electromagnetic steel plates are laminated and permanent magnets 22 whose cross-sectional shape is longer in the radial direction than in the circumferential direction are alternately arranged in the circumferential direction. In addition, a member in contact with both of the permanent magnets 22 in the radial direction is formed of a non-magnetic material 23, and a shaft (not shown) is disposed on the inside thereof.

  The permanent magnet 22 is divided into two in the radial direction, and includes an inner permanent magnet 221 having a relatively high residual magnetic flux density and a low coercive force, and an outer permanent magnet 222 having a relatively low residual magnetic flux density and a high coercive force. . For example, the inner permanent magnet 221 and the outer permanent magnet 222 are the same ferrite magnet, but those having different characteristics are arranged as described above. Further, the inner permanent magnet and the outer permanent magnet adjacent in the radial direction are magnetized in the same direction in the circumferential direction, and the magnetization directions of the permanent magnets adjacent in the circumferential direction are alternately magnetized so as to face each other.

  On the other hand, FIG. 2 shows a diagram in the case where the permanent magnet is not divided as a conventional example. The difference from FIG. 1 is that the permanent magnet 22 is changed to a permanent magnet 22a, and the rotor 2 becomes a rotor 2a accordingly. Further, in FIG. 2, when a material having a high residual magnetic flux density and a low coercive force is used for the permanent magnet 22 a, a portion 30 that is irreversibly demagnetized when a reverse magnetic field is applied to the permanent magnet is shown by hatching. In order to obtain a high torque, it is desirable to use a permanent magnet having a high residual magnetic flux density, but a permanent magnet having a high residual magnetic flux density generally has a small coercive force. Therefore, as shown in FIG. 2, the portion of the permanent magnet that faces the stator is likely to cause irreversible demagnetization. Moreover, when a permanent magnet having a high coercive force is used, irreversible demagnetization can be avoided, but the torque decreases because the residual magnetic flux density is low.

  Therefore, as shown in FIG. 1, the permanent magnet is divided into two in the radial direction, a permanent magnet having a high residual magnetic flux density and a low coercive force is arranged inside, and a permanent magnet having a low residual magnetic flux density and a high coercive force is arranged on the outside. By disposing, irreversible demagnetization can be made difficult to occur while suppressing a decrease in torque.

  Hereinafter, a second embodiment of the present invention will be described with reference to FIG.

  FIG. 3 is a quarter sectional view of the permanent magnet rotating electric machine according to the second embodiment of the present invention. The difference from FIG. 1 is that the permanent magnet 22 is changed to a permanent magnet 22b, and the inner peripheral side corner of the inner permanent magnet 221b and the outer peripheral side corner of the outer permanent magnet 222b are cut. Others are the same as FIG.

  By cutting the inner peripheral side corner of the inner permanent magnet 221b and the outer peripheral side corner of the outer permanent magnet 222b, the inner peripheral side of the inner permanent magnet in the portion 30 shown by hatching in FIG. The corner portion and the outer corner portion of the outer permanent magnet are eliminated, and the effect of suppressing irreversible demagnetization is obtained.

  A third embodiment of the present invention will be described below with reference to FIG.

  FIG. 4 is a quarter sectional view of the permanent magnet rotating electric machine according to the third embodiment of the present invention. The difference from FIG. 1 is that the rotor core 21 is changed to a rotor core 21c, and an inner peripheral convex portion 24 is formed on the inner peripheral side of the rotor core 21c. Accordingly, the rotor 2 is changed to the rotor 2c. Others are the same as FIG.

  By forming the inner peripheral convex portion 24, the magnetic flux in the peripheral portion thereof is guided toward the non-magnetic material 23, so that the inner peripheral side angle of the portion 30 shown in FIG. 2 that is easily irreversibly demagnetized is shown. The effect that the irreversible demagnetization of the part is relaxed is obtained. Further, by increasing the length of the inner circumferential side of the circumferential length of the inner circumferential convex portion 24, the rotor core 21c is fitted with the non-magnetic material 23, and the centrifugal force when the rotor rotates at high speed is reduced. The rotor core can be firmly fixed.

  Hereinafter, a fourth embodiment of the present invention will be described with reference to FIG.

  FIG. 5 is a quarter sectional view of the permanent magnet rotating electric machine according to the fourth embodiment of the present invention. The difference from FIG. 4 is that the permanent magnet 22 changes to a permanent magnet 22d, and the inner permanent magnet 221d and the outer permanent magnet 222d both have a circumferential length on the outer circumferential side shorter than a circumferential length on the inner circumferential side, The surface of the rotor core 21d that is in contact with the permanent magnet 22d is formed so as to be fitted to the permanent magnet 22d. Accordingly, the rotor 2c is changed to the rotor 2d. Others are the same as FIG.

  The rotor core 21 d is fitted to the nonmagnetic material 23 by lengthening the inner circumferential side of the circumferential length of the inner circumferential convex portion 24. Furthermore, the circumferential length on the outer peripheral side of the permanent magnet is shorter than the circumferential length on the inner peripheral side, and is fitted to the rotor core. As a result, even if the rotor rotates at a high speed and a centrifugal force is applied to the rotor core 21d and the permanent magnet 22d, an effect that the rotor is not separated is obtained.

  A fifth embodiment of the present invention will be described below with reference to FIG.

  FIG. 6 is a quarter cross-sectional view of the permanent magnet rotating electric machine according to the fifth embodiment of the present invention. The difference from FIG. 1 is that the permanent magnet 22 is changed to a permanent magnet 22e, and a gap 26 is provided between the inner permanent magnet 221e and the outer permanent magnet 222e. Further, the circumferential length of the outer permanent magnet 222e is shorter than the circumferential length of the inner permanent magnet 221e, and the portion of the rotor core 21e that is in contact with the outer permanent magnet 222e is extended in the circumferential direction. 25 is formed. Accordingly, the rotor 2 is changed to the rotor 2e. Others are the same as FIG.

  In this embodiment, for example, a ferrite magnet is used for the inner permanent magnet 221e, and a neodymium magnet or a samarium / cobalt magnet is used for the outer permanent magnet 222e. Further, the inner permanent magnet and the outer permanent magnet adjacent in the radial direction are magnetized in the same direction in the circumferential direction, and the magnetization directions of the permanent magnets adjacent in the circumferential direction are alternately magnetized so as to face each other.

  An irreversible demagnetization can be avoided by arranging a neodymium magnet or a samarium / cobalt magnet having a high coercive force in a portion that is irreversibly demagnetized. Further, since the neodymium magnet and the samarium / cobalt magnet have a residual magnetic flux density that is about two to three times higher than that of the ferrite magnet, the torque can be improved.

  However, if the inner permanent magnet and the outer permanent magnet are brought close to each other, the inner permanent magnet may cause irreversible demagnetization due to the high residual magnetic flux density of the outer permanent magnet. Therefore, by providing the air gap 26 between the inner permanent magnet and the outer permanent magnet, it can be avoided.

  In addition, neodymium magnets and samarium / cobalt magnets have a maximum energy product that is an order of magnitude higher than ferrite magnets, and both residual magnetic flux density and coercive force are high, so that the circumferential length of the outer permanent magnet can be shortened.

  As described above, by using a ferrite magnet as the inner permanent magnet and using a neodymium magnet or a samarium / cobalt magnet as the outer permanent magnet, the effects of avoiding irreversible demagnetization and further improving the torque can be obtained.

  Hereinafter, a sixth embodiment of the present invention will be described with reference to FIG.

  FIG. 7 is a quarter cross-sectional view of the permanent magnet rotating electric machine according to the sixth embodiment of the present invention. The difference from FIG. 6 is that the rotor core 21e is changed to the rotor core 21f, and an arm portion 27 that connects adjacent rotor cores is provided. Accordingly, the rotor 2e is changed to the rotor 2f. Others are the same as FIG.

  By connecting adjacent rotor cores, the rotor can be configured without separating the rotor cores. Furthermore, even if the rotor rotates at a high speed and a centrifugal force is applied to the rotor core 21f and the inner permanent magnet 221e, the rotor is not separated.

  The seventh embodiment of the present invention will be described below with reference to FIG.

  FIG. 8 is a quarter cross-sectional view of the permanent magnet rotating electric machine according to the seventh embodiment of the present invention. The difference from FIG. 1 is that a cover 28 is provided on the outer peripheral side of the rotor core 21 and the permanent magnet 22. As an example of the material of the cover, a stainless steel tube having a small thickness and high strength is used. Accordingly, the rotor 2 is changed to a rotor 2g. Others are the same as FIG.

  By providing the cover 28 on the outer peripheral side of the rotor core 21 and the permanent magnet 22, the rotor can be configured without separation of the rotor core. Furthermore, even if the rotor rotates at a high speed and a centrifugal force is applied to the rotor core 21 and the permanent magnet 22, an effect that the rotor is not separated is obtained. Furthermore, when the permanent magnet is cracked or chipped, the effect of preventing the broken pieces from being exposed to the outside of the rotor can be obtained.

  In the above description, the example in which the rotor magnetic pole is 8 poles with respect to 12 stator teeth has been described. However, if the rotor magnetic pole has 2 poles with respect to 3 stator teeth, The same can be realized with respect to nine rotor teeth and six rotor magnetic poles, and six stator teeth and four rotor magnetic poles. Further, other combinations such as an example of 10 or 14 rotor magnetic poles for 12 stator teeth or 8 or 10 rotor magnetic poles for 9 stator teeth can be similarly realized. is there.

  In the above description, the example in which the stator is disposed on the outside and the rotor is disposed on the inside has been described. However, the same can be realized when the stator is disposed on the inside and the rotor is disposed on the outside. is there.

In the above description, an example of a radial gap type having an air gap in the outer circumferential direction of the rotating shaft has been described. However, an axial gap type having an air gap in the axial direction of the rotating shaft, a linear type that linearly drives, Is also feasible in the same way.

1 stator, 2, 2a, 2b, 2c, 2d, 2e, 2f, 2g rotor,
9 Stator Teeth 11 Stator Core 12 Stator Teeth 13 Stator Windings 21, 21 c, 21 d, 21 e, 21 f Rotor Cores 22, 22 a, 22 b, 22 d, 22 e Permanent magnet 23 Nonmagnetic body 24 Inner circumferential convex part 25 Peripheral convex portion 26 Gap 27 Arm portion 28 Cover 30 Point where irreversible demagnetization easily occurs 110 Housing 120 Shaft 130 Flange 140 Bearings 221, 221b, 221d, 221e Inner permanent magnet 222, 222b, 222d, 222e Outer permanent magnet

Claims (10)

(The permanent magnet is divided into multiple parts in the direction facing the stator)
A stator having a stator core and a winding wound around a tooth portion of the stator core;
Permanently provided with a rotor core and a rotor in which a plurality of permanent magnets having different polarities are alternately arranged in the circumferential direction. In a magnet rotating electrical machine,
A permanent magnet rotating electric machine, wherein the permanent magnet is divided into a plurality of parts in a direction facing the stator. (Use a material with high coercivity for the permanent magnet closer to the stator)
In the permanent magnet rotating electric machine according to claim 1,
A permanent magnet rotating electrical machine characterized in that a material having a higher coercive force than a permanent magnet far from the stator is used for a permanent magnet closer to the stator among the plurality of permanent magnets. (Drop the corner of the permanent magnet)
In the permanent magnet rotating electric machine according to claim 1,
A permanent magnet rotating electric machine characterized by cutting corners of the permanent magnet. (The inner circumference of the rotor core is made longer than the permanent magnet)
In the permanent magnet rotating electric machine according to claim 1,
A permanent magnet rotating electrical machine characterized in that the rotor core is longer inward in the circumferential direction than the plurality of permanent magnets. (Make permanent magnet trapezoidal)
In the permanent magnet rotating electrical machine according to claim 4,
A permanent magnet rotating electrical machine characterized in that a circumferential length on the outer circumferential side of the permanent magnet is shorter than a circumferential length on an inner circumferential side, and the rotor core is fitted to the permanent magnet. (The permanent magnet far from the stator is a ferrite magnet, and the near permanent magnet is a neodymium magnet or samacoba magnet.)
In the permanent magnet rotating electric machine according to claim 1,
A permanent magnet rotating electric machine, wherein a ferrite magnet is used as a permanent magnet far from the stator, and a neodymium magnet or a samarium / cobalt magnet is used as a permanent magnet closer to the stator. (Provide air gaps between multiple permanent magnets)
In the permanent magnet rotating electric machine according to claim 1,
A permanent magnet rotating electrical machine, wherein a gap is provided between the plurality of divided permanent magnets. (Changing the circumferential length of multiple permanent magnets)
In the permanent magnet rotating electric machine according to claim 1,
A permanent magnet rotating electric machine characterized in that circumferential lengths of the plurality of divided permanent magnets are made different. (A core is connected between multiple permanent magnets)
In the permanent magnet rotating electric machine according to claim 1,
A permanent magnet rotating electrical machine characterized in that an arm for connecting the rotor cores sandwiching the plurality of divided permanent magnets is provided between the plurality of divided permanent magnets. (Rotor cover)
In the permanent magnet rotating electric machine according to claim 1,
A permanent magnet rotating electric machine, wherein a cover is provided on an outer peripheral portion of the rotor.