JPS6245788B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electric motor having a structure in which salient poles of an armature core are opposed to multipolar magnetized permanent magnets.

Conventionally, in electric motors in which the armature core has a salient pole structure and the salient poles are wound, an armature core with salient poles facing the entire circumference of a permanent magnet attached to the rotor is often used. Ta. As a result, the number of windings is large and the number of man-hours is complicated. As an improvement, an armature core with salient poles arranged to face a part of the permanent magnet has been proposed to reduce the number of windings and the number of man-hours required. However, in a motor with this type of structure, the force due to the interaction between the current and the magnet (force due to Fleming's left hand rule) acts only on a portion of the permanent magnet, so the force in the radial direction is generated along with the rotational force. act. This radial force is
As the permanent magnets rotate, their size and direction change, causing vibrations in the rotor. That is, it has the disadvantage that it does not provide an electric motor that performs smooth rotational motion.

In consideration of the above points, the present invention utilizes an armature core consisting of a plurality of salient pole blocks arranged at symmetrical or almost symmetrical positions with respect to the rotation axis of the motor, thereby reducing radial force. This is to prevent this from occurring and reduce vibration. In addition, the salient pole blocks are connected magnetically and mechanically by auxiliary salient poles to make the flow of magnetic flux uniform and to improve the positional accuracy of the salient poles.
Furthermore, the radial width of at least one auxiliary salient pole is made thinner, so that the radius of the auxiliary salient pole portion of the armature core as viewed from the center of rotation is made closer to the winding salient pole than the radius of the salient pole block portion. It is made relatively small so that necessary mechanical parts other than the motor parts can be easily placed relatively close to the rotation center of the motor. Hereinafter, the present invention will be explained based on illustrated embodiments.

FIG. 1 is a schematic diagram of an embodiment of the present invention. In the same figure, permanent magnets 2 attached to a cylindrical rotor 1 are arranged at equal pitch intervals (22.5°) or
It is an annular magnet with 16 poles magnetized at approximately equal pitches. The armature core 3 has three winding salient poles 4 _a
A salient pole block 3A consisting of ₁ , 4 _b1 , 4 _c1 and two auxiliary salient poles 6 _a1 , 6 _b1 , and three winding salient poles 4 _a
A salient pole block 3B consisting of ₂ , 4 _b2 , 4 _c2 and two auxiliary salient poles 6 _a2 , 6 _b2 , and the salient pole block 3A
and auxiliary salient poles 7 and 8 provided between and 3B. The salient pole blocks 3A, 3B are arranged at 180° or approximately 180° with respect to the rotational axis of the rotor 1, that is, the center point O, and the salient poles _4a1 to _4c1 , _4a2 to 4 _c2 and each auxiliary salient pole 6 _a1 , 6 _b1 , 6 _a2 , 6 _b2 , 7, 8 are opposed to the magnetized surface of the permanent magnet 2 with a required gap.

In addition, the pitch at which the magnetic flux flows from the permanent magnet 2 of each of the winding salient poles 4 _a1 to 4 _c1 and 4 _a2 to 4 _c2 (this is called the effective opposing pitch) is the pitch at the tip of the salient pole (this is called the effective opposing pitch). It is wider than the opposing pitch (referred to as the opposing pitch) and is approximately 22.5 degrees, and is approximately equal to the one magnetic pole pitch (22.5 degrees) of the permanent magnet 2. The effective opposing pitch of the auxiliary salient poles 6 _a1 , 6 _b1 , 6 _a2 , 6 _b2 between the winding salient poles is approximately equal to 7.5°. Further, the effective opposing pitch of the auxiliary salient poles 7 and 8 provided between the salient pole blocks 3A and 3B is approximately 97.5°. Armature core 3 is
For example, it is formed by laminating many silicon steel plates,
Each of the salient poles is integrally formed as shown in the figure.

Each of the winding salient poles 4 _a1 to 4 _c1 and 4 _a2 to 4 _c2 have the following:
One drive coil each 5 _a1 , 5 _b1 , 5 _c1 , 5 _a
2 , 5 _b2 , 5 _c2 are applied. The six drive coils are divided into independent three-phase coil groups 5a ₁ , 5a ₂ and 5b ₁ , 5b ₂ and 5c ₁ , 5c ₂ with respect to the relative positional relationship with the magnetic poles of the permanent magnet 2. I know. Therefore, for example, the rotational position of the permanent magnet 2 is detected by a magnetic sensing element such as a Hall element, and a group of coils to which a constant current is applied is switched by a drive circuit 30 using a semiconductor switch as illustrated in FIG. If so, the rotor 1 can be rotated continuously in the same direction. Since such a drive circuit 30 may be a well-known one, a detailed explanation thereof will be omitted here.

Now, for example, if current is flowing through the drive coils 5a ₁ and 5a ₂ , the relative phase between the winding salient poles 4a ₁ and 4a ₂ to which the drive coils are applied and the magnetic poles of the permanent magnet 2. Since the relationships are equal (in phase) and 180° opposite to the axis of rotation, the radial forces cancel out and only rotational forces occur. As a result, an electric motor that rotates smoothly and has less vibration is obtained.

Next, the effect of the auxiliary electrodes 7 and 8 provided between the salient pole blocks 3A and 3B will be explained with reference to FIG. FIG. 3 is an enlarged development view of the main part showing the distribution of magnetic flux in the groove 10 between the winding salient pole 4a ₁ and the auxiliary salient pole 7. FIG. In the figure, most of the magnetic flux emitted from the magnetic poles of the permanent magnet 2 is absorbed by the salient poles 4a ₁ and 7, avoiding the grooves 10 having high magnetic resistance, as indicated by arrows. As a result, the magnetic flux up to the intermediate line K of the groove 10 flows into the winding salient pole _4a1 . The same applies to the other winding salient poles 4b ₁ , 4c ₁ , 4a ₂ , 4b ₂ , 4c ₂ . Therefore, the effective opposing pitches of the salient poles for each winding are approximately equal, and there is no variation in the magnetic flux interlinking with each drive coil. As a result, an electric motor with less fluctuation in torque is obtained.

On the other hand, when the auxiliary salient poles 7 and 8 are not provided, the effective opposing pitch of the winding salient poles 4a ₁ , 4c ₁ , 4a ₂ , and 4c ₂ at both ends of the salient pole blocks 3A and 3B is widened. , causing variations in the magnetic flux interlinking with each drive coil. As a result, the electric motor produces torque fluctuations.

Next, the auxiliary salient poles 6a ₁ provided between the winding salient poles,
The effects of 6b ₁ , 6a ₂ , and 6b ₂ will be explained.

As shown in FIG. 3, the magnetic flux emitted from the permanent magnet 2 is absorbed by the winding salient pole and the auxiliary salient pole.

In this example, the auxiliary salient poles are arranged so that the effective opposing pitch of each winding salient pole is approximately equal to one magnetic pole pitch (22.5°) of the permanent magnet 2. As a result, the maximum value of the magnetic flux flowing into each winding salient pole increases, and the range of uniform increase rate (or decrease rate) becomes wider, resulting in a highly efficient electric motor with less torque fluctuation.

As shown in the above embodiment, an armature core is used in which a salient pole block having a plurality of salient poles for windings is arranged at 180° or approximately 180° symmetrical positions with respect to the rotational axis of the rotor. In this case, since no radial force is generated, an electric motor that performs smooth rotational motion, has less vibration, and has a smaller number of windings can be obtained. In general, the above-mentioned effects can be obtained by arranging a plurality of salient pole blocks at symmetrical or nearly symmetrical positions with respect to the rotation axis of the rotor.

Furthermore, if an auxiliary salient pole is arranged between the salient pole blocks and magnetically connected to prevent unnecessary magnetic flux from flowing into the winding salient poles at both ends of each salient pole block, each winding salient pole can be connected magnetically. Variations in the magnetic flux flowing into the poles are eliminated, and torque fluctuations are reduced. As shown in the above embodiment, if the salient pole blocks are magnetically connected by auxiliary salient poles and each salient pole is formed integrally with a laminate of silicon steel plates, for example, the position of each salient pole is The accuracy is improved and the effects of the present invention can be better realized. However, the same effect as described above can be obtained even if each salient pole is formed from a separate magnetic member and combined to form the armature core in order to facilitate winding. Further, even if two or more auxiliary salient poles are provided between the salient pole blocks, the above-mentioned effect remains the same.

Furthermore, in the embodiment of the present invention described above, each winding salient pole 4a ₁ of the salient pole blocks 3A, 3B
Auxiliary salient poles 6a ₁ to 6 on both sides of ~4c ₁ , 4a ₂ ~4c ₂
b ₁ , 6a ₂ , 6b ₂ , 7, and 8 are arranged so that the effective opposing pitch of each winding salient pole is equal to or approximately equal to one magnetic pole pitch of the permanent magnet 2. Therefore, the magnetic flux flowing into the winding salient poles 4a ₁ to 4c ₁ , 4a ₂ to 4c ₂ , that is, the respective drive coils 5a ₁ to 5c ₁ ,
The maximum value of the magnetic flux interlinking with 5a ₂ to 5c ₂ becomes large, resulting in a highly efficient electric motor.

Torque ripple is also reduced. moreover,
If the effective opposing pitch of the salient poles for each winding is set to an odd number of three or more times the pitch of one magnetic pole of the permanent magnet, it is possible to realize a motor with a significantly smaller number of drive coils than the number of magnetic poles.

Further, as shown in the embodiment shown in FIG.
The salient pole blocks are arranged 180° or approximately 180° symmetrically with respect to the rotation center O of the salient pole block, and the distance between the salient pole blocks is The pitch (120°) between the centers of adjacent salient poles for winding is more than doubled, and the salient pole blocks are magnetically and mechanically connected by auxiliary salient poles 7 and 8. The magnetic pole of armature core 3 and the salient pole of armature core 3 are made to face each other all the way around the entire circumference,
In addition, the radial width of at least one of the auxiliary salient poles 7 and 8 is made thinner so that the radius of the auxiliary salient pole part of the armature core as seen from the rotation center O is smaller than the radius of the salient pole block part. If they are made as small as the auxiliary salient poles, mechanical parts other than motor parts can be easily arranged on the outer edges of the auxiliary salient poles 7 and 8. That is, while the required mechanical parts are arranged close to the rotation center O, the substantial radius of the electric motor (the outer edge radius of the salient pole block portion) can be increased. As a result, if the present invention is applied to a direct drive type electronic commutator motor such as a tape recorder, the overall mechanical design becomes easy and an electric motor that generates a large torque can be obtained. In addition, when applied to spindle motors for floppy disks and compact disks, it is possible to configure an electric motor that generates sufficient starting torque while ensuring that the movement range of the magnetic head or optical head is close to the center of rotation of the electric motor. becomes very easy.

FIG. 4 shows a main part configuration diagram of another embodiment of the present invention. In the figure, the permanent magnets 2 attached to the rotor 1 are annular magnets with 16 poles magnetized at equal pitch intervals (22.5 degrees) or approximately at equal pitch intervals, as in the previous embodiment. The armature core 13 is
A salient pole block 13A consisting of three winding salient poles 14a ₁ , 14b ₁ , 14c ₁ and two auxiliary salient poles 16a ₁ , 16b ₁ and three winding salient poles 14a ₂ , 14b ₂ ，
14c ₂ and two auxiliary salient poles 16a ₂ and 16b ₂ , and auxiliary salient poles 17 and 18 provided between these salient pole blocks 13A and 13B. Salient pole block 1 above
3A and 13B are arranged 180° or approximately 180° symmetrically with respect to the rotation axis of the rotor 1, that is, the center point O, and each salient pole for winding 14a to 14c ₁ , 14a ₂
~14c ₂ and each auxiliary salient pole 16a ₁ , 16b ₁ , 16
a ₂ , 16b ₂ , 17, and 18 face the magnetized surface of the permanent magnet 2 with a required gap. Also in this example,
The effective opposing pitch of each of the winding salient poles 14a ₁ to 14c ₂ is approximately equal to one magnetic pole pitch (22.5°) of the permanent magnet 2, and is approximately 20° (approximately 0.9 times).
In addition, auxiliary salient poles 16a ₁ , 16b ₁ , 16a ₂ , 16b ₂
The effective opposing pitch is approximately 10°, and the auxiliary salient poles 17 and 18 are approximately 100°. The armature core 13 is formed by laminating silicon steel plates, for example, and integrally has salient poles.

Salient poles for each winding 14a ₁ , 14b ₁ , 14c ₁ , 14
a ₂ , 14b ₂ , 14c ₂ each have one drive coil 15a ₁ , 15b ₁ , 15c ₁ , 15a ₂ , 15b ₂ ,
15c ₂ is wound, and these are independent three-phase coil groups with respect to the relative positional relationship with the magnetic poles of the permanent magnet 2, namely 15a ₁ , 15a ₂ and 15b ₁ , 15b ₂ and 15
It is divided into c ₁ and 15c ₂ . Therefore, the rotor 1 can be continuously rotated in the same direction using the same drive circuit as in the embodiment shown in FIG. 1 described above.

In the embodiment shown in FIG. 4, the salient poles 14a ₁ to 14c ₁ , 14a ₂ to 14 of the armature core 13
c ₂ , 17, 18, in the portions facing the magnetic poles of the permanent magnets 2, are provided with auxiliary grooves (representatively indicated by 21) in a direction parallel to the rotational axis of the rotor 1, that is, in a direction perpendicular to the plane of the drawing. armature core 1)
By changing the state of magnetic fluctuation of 3, permanent magnet 2
The aim is to reduce the cogging force caused by the interaction with the The effect will be explained below. Generally, cogging force is generated when magnetic energy stored in the magnetic field between the permanent magnet 2 and the armature core 13 changes depending on the rotational position of the armature core. Since magnetic energy is a quantity related to the square of the magnetic flux density, the permanent magnet 2 has a basic period of one magnetic pole pitch, and the magnetic fluctuation of its harmonic component (the square of the magnetic flux density generated by the permanent magnet 2) related quantities). Therefore, it is sufficient to consider the magnetic fluctuation of the armature core 13 with one magnetic pole pitch of the permanent magnet 2 as the basic period, and generally,
If the amount of variation is reduced, the cogging force will be reduced.

The magnetic fluctuation of the armature core 13 (the amount related to the permeance of the armature core 3 seen from each point on the surface of the permanent magnet 2) is caused by the groove 20 between the salient poles and the auxiliary groove 2.
1. As is clear from FIG. 3, the magnetic flux emitted from the magnetic poles of the permanent magnet 2 is absorbed by the salient poles, avoiding the grooves with high magnetic resistance. Therefore, even if the depth of the groove is shallow like the auxiliary groove 21 shown in FIG. 4, it is magnetically almost equivalent to the groove 20 between the salient poles. In the embodiment shown in FIG. 4, the entire grooves consisting of the grooves between the salient poles of the armature core and the auxiliary grooves are spaced at equal angular intervals (10°) or at approximately equal angles with respect to the rotation center O of the rotor. They are placed at intervals all around the circumference. As a result, there are nine grooves for four magnetic poles (90 degrees) of the permanent magnet 2. Therefore, below, the angular spacing of the armature core 13 is 90
Nine grooves a, b, c, d, e, f, g,
The effect of the auxiliary groove will be explained regarding the magnetic fluctuation due to h and i.

The magnetic fluctuation due to the grooves a to f between the salient poles is expressed as the fifth
Shown in Figure a. That is, with groove a as a reference, groove b has a phase difference of 8/9 of one magnetic pole pitch, and the fluctuation states (waveforms) are the same. Similarly, the phase differences between grooves c, d, e, and f are 3/9, 2/9, 6/9, and 5/9 of one magnetic pole pitch, respectively. the result,
If the magnetic fluctuations due to each of the grooves a to f (indicated by the broken lines in FIG. 5a) are combined, the results will be as shown by the solid lines in the same figure.

On the other hand, the auxiliary grooves g, h, and i have a phase difference of 4/9, 7/9, and 1/9 of one magnetic pole pitch, respectively, with respect to the groove a, and if these magnetic fluctuations are combined, Fifth
It will look like the solid line in Figure b. Therefore, the groove a between the salient poles
If the magnetic fluctuations due to ~f and the magnetic fluctuations due to auxiliary grooves g~i are combined, the result is as shown in Fig. 5c. Comparing this with the magnetic fluctuation amount caused by the grooves a to f between the salient poles when no auxiliary grooves are provided [FIG. 5a], the fluctuation frequency becomes higher and the fluctuation level becomes smaller.

Therefore, the amount of magnetic fluctuation of the armature core 13 is reduced, and the cogging force is reduced. In general, the higher the frequency of fluctuation, the smaller the magnitude of fluctuation in the permanent magnet 2, and
The cogging force generated by the interaction between the permanent magnet 2 and the permanent magnet 2 becomes even smaller.

In the above embodiment, an auxiliary groove having almost the same magnetic effect as the groove between the salient poles is provided, and the entire groove consisting of the groove between the salient poles and the auxiliary groove is aligned with respect to the center of rotation. Although the auxiliary grooves are arranged at angular intervals, the effect of the auxiliary grooves is not limited to such a case. Further, it is not necessary to provide auxiliary grooves on both the winding salient pole and the auxiliary salient pole.

Generally, an auxiliary groove for changing the state of magnetic fluctuation of the armature core is provided in the part of the salient pole of the armature core that faces the permanent magnet, and the relative positional relationship with the magnetic pole of the permanent magnet is If the magnetic fluctuations due to the grooves between the salient poles of the iron core are offset by the magnetic fluctuations due to the auxiliary grooves, and the combined fluctuations are reduced, the cogging force will be reduced. In particular, if the auxiliary groove is provided to increase the frequency of fluctuation as in the above embodiment, the cogging force can be easily reduced.

As is clear from the above description, the present invention can realize an electric motor that has a small number of windings, is easy to manufacture, has small cogging force and torque fluctuations, and has very little vibration. In particular, the present invention is extremely effective when used as an electronic commutator type motor for audio equipment.

In the above-described embodiments of the present invention, a three-phase drive type electric motor was explained as an example, but the present invention can also be implemented in a general multi-phase drive type electric motor.

Therefore, the number and arrangement of the winding salient poles included in each salient pole block are not limited to those in the above-described embodiments. Further, the present invention is not limited to an adductor type, but may be an abductor type. Further, each salient pole of the armature core is not limited to a laminate of silicon steel plates, and may be formed by bending a steel plate. It goes without saying that various other modifications can be made without changing the gist of the present invention.

[Brief explanation of the drawing]

Fig. 1 is a main part configuration diagram of an embodiment of the present invention, Fig. 2
The figure shows an example of the connection configuration of the drive coil group and the drive circuit in the same embodiment. FIG. 4 is a block diagram of a main part of another embodiment of the present invention, and FIGS. 5a, b, and c are diagrams showing magnetic fluctuations for explaining the effects of the embodiment of FIG. 4. 1...Rotor, 2...Permanent magnet, 3,13...
Armature core, 4a ₁ , 4b ₁ , 4c ₁ , 4a ₂ , 4b ₂ , 4
c ₂ , 14a ₁ , 14b ₁ , 14c ₁ , 14a ₂ , 14b ₂ ,
14c ₂ ... Salient pole for winding, 5a ₁ , 5b ₁ , 5c ₁ , 5
a ₂ , 5b ₂ , 5c ₂ , 15a ₁ , 15b ₁ , 15c ₁ , 15
a ₂ , 15b ₂ , 15c ₂ ... Drive coil, 7, 8, 1
7, 18, _{6a 1} , 6b ₁ , 6a 2 , 6b ₂ , 16a ₁ , 1
6b ₁ , 16a ₂ , 16b ₂ ... Auxiliary salient pole, 3A, 3
B, 13A, 13B... Salient pole block, 10, 2
0a to f... Grooves between salient poles, 21, g to i... Auxiliary grooves.

Claims (1)

[Scope of Claims] 1. A rotor in which four or more N and S poles are alternately arranged at equal pitch intervals or approximately equal pitch intervals, and each of which has a permanent magnet formed in an annular shape; Two or more sets of salient pole blocks having a plurality of salient poles for windings, an armature core having two or more auxiliary salient poles provided between the salient pole blocks, and each winding of the salient pole blocks. a plurality of phase drive coils wound around salient poles, the two or more sets of salient pole blocks of the armature core are arranged at symmetrical or nearly symmetrical positions with respect to the rotation center of the rotor; The pitch between the centers of the adjacent salient poles for winding between the salient pole blocks is made larger than the pitch between the centers of the adjacent salient poles for winding in the salient pole block, and the salient pole blocks The magnetic poles of the rotor are arranged inside the salient poles of the armature core, and the magnetic poles of the rotor and the salient poles of the armature core are connected magnetically and mechanically by the auxiliary salient poles. The auxiliary salient poles are arranged to face each other all around the entire circumference, and have a thin radial width of at least one of the auxiliary salient poles, as viewed from the center of rotation at the auxiliary salient pole portion of the armature core. An electric motor characterized in that the radius of the salient pole block is smaller than the radius of the salient pole block by an amount corresponding to the salient pole for winding. 2. A rotor in which four or more N and S poles are alternately arranged at equal pitch intervals or approximately equal pitch intervals, and a rotor in which permanent magnets are substantially formed in an annular shape, and each rotor is used for a plurality of windings. an armature core having two or more sets of salient pole blocks having salient poles, two or more auxiliary salient poles provided between the salient pole blocks, and winding around each winding salient pole of the salient pole blocks; The two or more sets of salient pole blocks of the armature core are arranged at symmetrical or almost symmetrical positions with respect to the rotation center of the rotor, and the salient pole blocks in the salient pole blocks The pitch between the centers of the adjacent salient poles for winding is made larger than the pitch between the centers of the adjacent salient poles for winding, and the pitch between the centers of the salient poles for winding is made larger between the salient pole blocks. The magnetic poles of the rotor are arranged inside the salient poles of the armature core, and the magnetic poles of the rotor and the salient poles of the armature core extend around the entire circumference. The radial width of at least one of the auxiliary salient poles is made thin so that the radius of the auxiliary salient pole portion of the armature core when viewed from the center of rotation is set to be equal to the radius of the salient pole block. an auxiliary groove is formed in a portion of at least one of the salient winding poles of the armature core that is smaller than the radius at the portion corresponding to the winding salient pole, and that faces the magnetic pole of the rotor; With respect to the relative positional relationship with the magnetic poles of the rotor when one magnetic pole pitch of the rotor is used as a basic period, the magnetic fluctuations caused by the grooves between the salient poles of the armature core are absorbed by the auxiliary grooves. An electric motor characterized in that magnetic fluctuations are offset.