JPH0328898B2 - - Google Patents

Abstract

PURPOSE:To restrict a rotating irregularity to required minimum limit without decreasing the efficiency of a motor by splitting all or part of poles in a circumferential direction to form a main pole and an interpole, and forming the poles in nonequal shapes. CONSTITUTION:A core 4 which encloses a coil 3 from one flat side of the coil 3 and a core 5 which encloses the coil 3 from the other flat side of the coil 3 are secured to a shaft 2 to construct an armature 6. The cores 4, 5 are radially branched toward a field 1, the branched ends are bent perpendicularly along the outer periphery of the coil 3, main poles 4a, 5b and auxiliary poles 4b, 5b respectively extend from the cores 4, 5, the auxiliary poles 4b, 5b and the main poles 4a, 5a are spaced and disposed at the prescribed interval, and the centers of the poles formed by the poles 4a, 5a and 4b, 5b at the energizing time are disposed at the positions of 0 deg. and 90 deg..

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a core for an armature of a DC motor, an AC motor, a rotary plunger, or the like, which is generally suitable for use in a rotating electric machine.

A permanent magnet ring magnetized with 2n poles (n is a natural number of 2 or more) in which adjacent poles on the circumferential surface are different from each other, and a coil wound concentrically around the shaft center from both sides of the flat side of the coil. The cores are wrapped along the magnetic path, and the cores are intertwined alternately on the circumferential surface facing the magnetized surface of the ring of the coil to form a 2n-pole structure in which adjacent poles on the circumferential surface of the coil are different from each other. In order to avoid the starting dead center of a multi-pole DC motor, which is composed of an armature in which magnetic poles are formed and a switching means that switches the current direction of the coil in accordance with the rotation, the permanent magnet ring of the core is The shape of the facing surface is formed magnetically asymmetrical with respect to the center of the magnetized pole of the ring, so that the center of the magnetic pole of the armature when energized is different from the natural stopping position due to the attractive force of the armature's permanent magnet ring when energized. The winding is caused to occur at a position shifted in the direction of relative rotation of the armature, and the armature winding is wound concentrically with respect to the axis, which makes winding easy and allows for a large number of windings.
Furthermore, the present applicant has already proposed a multi-pole DC motor that can be easily flattened (Japanese Patent Application No. 159710/1982).

As a specific example for avoiding the starting dead center, the shape of the surface of the core that faces the permanent magnet ring forming the magnetic path of the concentrically wound coil is aligned in the relative rotational direction of the armature. proposed.

However, in a DC motor with a concentric armature winding, the core shape of the armature is magnetically asymmetric to avoid starting dead center, so it is inevitable that some degree of uneven rotation will occur. do not have.

In other words, in a DC motor with a permanent magnet ring as the field and a concentric armature winding as described above, in order to increase efficiency, the switching point of the current to the armature is set between the center of the armature's magnetic pole and the field. On the other hand, since the armature windings are concentric windings, if the armature stops at a position where the center of the armature's magnetic poles and the center of the field's magnetic poles match, the activation will occur. It becomes impossible.

This means that even if the core shape of the armature is magnetically asymmetric, the armature becomes de-energized at a position where the magnetic pole centers of the armature and the field coincide, and furthermore, even if the core shape of the armature is made magnetically asymmetric, If the suction torque with the armature is smaller than the load torque, the armature will continue to stop at the same position and will not start.

Therefore, in order for the DC motor with the above configuration to start without fail to avoid the starting dead center, when the armature becomes de-energized at the position where the magnetic pole centers of the armature and the field coincide, It is necessary that the attraction torque of the permanent magnet exceeds the load torque, thereby avoiding the starting dead center, but since the attraction torque of the permanent magnet ring is large when the armature is in a de-energized state, The rotation unevenness mentioned above will occur.

The inventor of the present invention set out the following conditions to minimize rotational unevenness: The load torque must be slightly higher than the current load torque.

(b) At the position of (a), the suction torque shall be the maximum torque.

I found out.

However, as in the embodiments of the above-mentioned patent application, the above condition (b) cannot be satisfied by simply determining the shape of the field-facing surface of the armature core. That is, even if the length and width of the raised portion of the core are changed, the maximum torque position of the suction torque does not change, and the maximum torque position cannot be set to an arbitrary position.

On the other hand, in order to increase the efficiency of the DC motor as described above, the magnetic flux of the field must not only pass through the core that wraps the armature coil from both flat sides, but also pass between the adjacent N and S poles of the field poles. It is preferable to pass through the part of the core located opposite to the permanent magnet ring.

To this end, it is sufficient to minimize the number of sources between adjacent cores, which are intricately arranged and alternately of different polarities on the circumferential surface of the concentrically wound armature winding, but in the embodiment of the application mentioned above, If the magnetic field source is made smaller by simply changing the shape of the field facing surface of the core, the attraction torque of the permanent magnet becomes too large and a large starting current is required.

The present invention has been made in view of the above circumstances, and its object is to form a magnetic pole formed on the field-opposed circumferential surface of a concentrically wound armature winding from a main pole and a complementary pole. and the position of the interpole,
To provide a core for an armature of a motor, etc., which satisfies the conditions (a) and (b) above by changing the shape, has minimal rotational unevenness, and can improve motor efficiency. The feature is that the coil is wound concentrically around the axis and is bent from both end faces to the circumferential surface, and the part located on the circumferential surface is a magnetic pole, and the In a core for an armature of a motor, etc., in which magnetic poles of 2n (n is a natural number of 2 or more) are arranged alternately in the circumferential direction to form a magnetic pole of 2n (n is a natural number of 2 or more) poles, all or part of the magnetic poles are divided into two in the circumferential direction. forming a pole and a commutative pole, and at a relative stop position of the armature and field magnet when energized, the circumferential midpoint of the magnetic pole or the circumferential midpoint between the N and S poles of the magnet pole; The shape of the main pole and/or the complementary pole is formed magnetically asymmetrically so that the center of the magnetic pole of the armature is at a relatively shifted position when energizing is started.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a case in which a preferred embodiment of the present invention is applied to a motor will be illustrated and explained in detail based on the accompanying drawings.

In FIG. 1, which is a plan view of a four-pole, inner-rotor type motor, reference numeral 1 denotes a field consisting of a permanent magnet ring magnetized into four poles.

2 is a shaft, and a coil 3 is wound around this shaft 2.

4 is a core according to the present invention that wraps around the coil 3 from one of the flat sides of the coil 3, and 5 is a similar core that wraps around the coil 3 from the other flat side of the coil 3. Configure child 6.

These cores 4 and 5 branch radially toward the field 1, and as shown in FIG.
The core 4 is bent at right angles along the outer peripheral surface of the core 4.
A main pole 4a and a commutative pole 4b are provided from the core 5, and a main pole 5a and a commutative pole 5b are provided from the core 5, respectively.

The commutating poles 4b, 5b and the main poles 4a, 5a are spaced apart from each other with a predetermined gap, and the center of the magnetic poles formed by the main poles 4a, 5a and the commutating poles 4b, 5b when energized is 0°, 90°, (180°,
270° is the position (not shown). Note that FIG. 1 shows a state in which the magnetic pole center of the field and the magnetic pole center of the armature 6 coincide.

Therefore, in FIG. 1, the armature 6 rotates counterclockwise in the case of a DC motor, and the current direction of the coil 3 is determined by a switching means (not shown) at the position shown in FIG. Therefore, the rotation is switched so that the rotation continues.

In this way, the magnetic poles of the armature 6 are changed to the main poles 4a, 5a.
By separately forming the commutating poles 4b and 5b, the rotating torque (attraction torque between the field and the armature) when the armature 6 is not energized and under no load is reduced.
As shown in Fig. 3, if the rotation torque when the armature 6 rotates to the left due to suction torque is 1, and the rotation torque when the armature 6 rotates to the right is +, then , the armature 6 rotates counterclockwise due to the negative rotational torque and stops at a stable natural stop position P1 under no load. As the armature 6 further rotates to the left, the armature 6 passes through a circumferential angle portion where positive rotational torque is generated, and eventually reaches an unstable stopping position P.
2, and when this stop position P2 is exceeded, the armature 6 rotates counterclockwise toward the natural stop position P1 in the forward rotation direction.

By changing the relative shapes and positions of the main poles 4a, 5a and the complementary poles 4b, 5b, when the armature 6 is in the position shown in FIG. 1, that is, the armature 6 and the field 1 are By locating the center of the magnetic pole of the rotor, it is possible to maximize the rotary torque when the armature current is at the switching position, and to set the maximum rotational torque to be slightly larger than the required load torque at startup.

Therefore, the armature 6 will not stop at the position shown in Fig. 1 under load, and therefore, starting dead center will always be avoided, and the rotational torque of the armature 6 will be lower than the load torque at the time of starting. Since it is slightly larger and the minimum necessary size, rotational unevenness of the armature 6 is also minimized.

In addition, the main poles 4a, 5a and the complementary poles 4b, 5b
can be formed into any shape as shown in Fig. 4a and b.In short, it is divided into two in the circumferential direction front and back to form a main pole and a commutative pole, and the shape of the main pole or (and) the commutative pole is may be formed magnetically asymmetrically. As a result, when the armature and the field magnet are at a relative stop position when de-energized, the circumferential midpoint of the magnet poles or the circumferential midpoint between the magnet poles, and the center of the armature's magnetic pole when starting and energized. will be relatively shifted. Moreover, it may be a part of the armature magnetic pole rather than all of it. Furthermore, any of the field rotation type, outer rotor type, and inner rotor type can be constructed in the same manner, and can also be used as an AC motor.

Next, a specific example of a DC motor including an armature core in which the armature magnetic pole is formed of a main pole and a commutative pole will be described.

First, in Fig. 5, which shows a DC motor that is easy to assemble and has excellent practicality, 11 is a permanent magnet ring serving as a stator, N,
Six poles are magnetized on the inner peripheral surface so that the S poles are alternate. Note that by setting the number of magnetic poles to 2 (2m+1) poles (m is a natural number of 1 or more), opposing magnetic poles are always different.

A coil 12 is formed by winding an electric wire 12b around a circular bobbin 12a having a shaft insertion hole in the center.

13 is a lower core formed according to the present invention;
Disc portion 1 arranged concentrically on the lower surface of the coil 12
3a, a main pole 13b and a commutative pole 13c, which are bent at right angles along the outer circumferential surface of the coil 12, and three branches are protruded from the circumference of the disk portion 13a at an angle of deviation of 120 degrees.
It is formed by pressing a magnetic material such as an iron plate.

14 is a coil 1 also formed according to the present invention.
The upper core is disposed concentrically on the upper side of the lower core 13, and similarly to the lower core 13, it is composed of a disk portion 14a, a main pole 14b, and a subpole 14c.

The lower core 13 and the upper core 14 are connected to the main pole 13b,
The commutative pole 13c is located between the main pole 14b and the commutative pole 14c, and is arranged on both sides of the coil 12, and the main pole 13b and the main pole 14b adjacent to the circumferential surface of the coil 12 are different from each other. Six magnetic poles are formed.

15 is a commutator, which is a disc 15a made of an insulating material and having a shaft insertion hole in the center.
and six commutator pieces 15b attached radially from the center on one side of the disc 15a. Every other commutator segment 15b is electrically connected to form two commutator groups, and the coil 12 is connected to each commutator group.

Reference numeral 16 denotes a shaft, which has a flange 16a formed approximately at the center in the length direction, and a stepped portion 16b at the lower end.
A stepped portion 16c is formed, and an engaging portion for the transmission mechanism is formed on the upper end side circumferential surface.

The commutator 15, upper core 14, coil 12, and lower core 13 are inserted into this shaft 16,
The lower core 13 is caulked and fixed at the stepped portion 16b.

Reference numeral 17 denotes a brush, and a rectangular plate made of phosphor bronze is formed with an arc-shaped notch 17a serving as a relief part for the flange 16a at the center of one long side, and a brush 17a is formed at both corners located on this long side as will be described later. A hole 17b that engages with the case is drilled, a hole 17c is drilled at both corners located on the other long side to which a lead wire 18 for power supply is connected, and a slider to the commutator 15 is drilled in the center of the surface. The contact portion 17d is formed by cutting and raising. Note that two sliding contact portions 17d are formed to ensure contact with the commutator 15.

Then, two brushes 17 are arranged at point-symmetrical positions sandwiching the circumferential surface of the shaft 16, and each sliding contact portion 17
d are in contact with the commutator group of the commutator 15, respectively.

Reference numeral 19 denotes a case molded from a plastic material, and a recess 19a into which the permanent magnet ring 11 is inserted is formed in the upper surface of the case, and a bearing hole in which the shaft 16 is supported by the stepped portion 16c is formed at the center of the bottom surface of the recess 19a. 19b is drilled. Further, the hole 1 of the brush 17 is provided on the upper surface, which is the surface where the recess 19a is formed.
7b, four engaging protrusions 19c are drilled at each corner of the upper surface, and holes 19d are provided at each corner of the top surface, corresponding to the holes 17c of the brush 17, through which the lead wires 18 are inserted and held.
is drilled.

20 is a plastic plate cover attached to the upper surface of the case 19, and the engaging protrusion 19c
An engaging hole 20a is formed at a corresponding position, and each corner is cut out to facilitate connection of the lead wire 18 to the brush 17. In addition, a bearing hole 2 for inserting and supporting the shaft 16 is provided in the center of the surface.
0b is drilled.

Each of the components includes a permanent magnet ring 11 disposed in a recess 19a, and an armature consisting of a coil 12, a lower core 13, an upper core 14, a commutator 15, and a shaft 16, as shown by the dashed line in the figure. , the stepped portion 16c of the shaft 16 is connected to the bearing hole 19b.
is inserted into the permanent magnet ring 11 and placed in the center of the permanent magnet ring 11.
The two brushes 17 are inserted into the holes 17b of the engagement protrusions 19.
c, align the engagement hole 20a of the cover 20 with the engagement protrusion 19c, and insert the shaft 16 into the bearing hole 20b to close the case 19.
The engagement protrusion 19c is fixed to the cover 20 by heat welding or the like, and the lead wire 18 is passed through the hole 19d and inserted into the hole 17c of the brush 17 and soldered to perform assembly.

In this DC motor, the armature coil is wound concentrically around the shaft, making it easy to wind the motor, and in combination with the plate-shaped commutator and brushes, it can be made flat and compact. The brushes are sandwiched between the case and cover and fixed in position, making assembly extremely easy.Also, since the number of poles is 2 (2m+1), opposing brushes are the same and are point symmetrical about the rotation axis. Furthermore, since the motor is flat, a spur gear can be used instead of an inefficient worm and worm gear in the rotation transmission mechanism of the motor.

Note that the armature core according to the present invention can of course be used for AC motors as well.

In the case of an AC motor, for example, in the DC motor shown in FIG. 5, if the commutator 15 is omitted and a permanent magnet is configured to rotate as a rotor, and single-phase AC is directly supplied to the coil 12, an AC synchronous motor ( For example, it can be operated as a small timer, electric clock, etc.). Note that the rotation direction can be regulated by providing a known reverse rotation prevention stopper or one-way rotation clutch in the external transmission mechanism so that the motor rotates only in one direction, similar to a conventional AC motor. . Further, the rotation direction can also be selected depending on the shapes of the main pole and the complementary pole.

In other words, since the magnetic circuit is complexly combined, the characteristics of the magnetic circuit are changed depending on the shape of the main pole and the complementary pole.
The rotation direction can be selected. To explain with an example, as is clear from the perspective view of the main part of the shaft 21 shown in FIG. 6, which is virtually extended,
The electrical circuit when the power is off is as follows.

(Solid line arrow) N pole of magnet ring 22 → Compensating pole 23b of lower core 23 → Shaft 21 → Upper core 24
Commuting pole 24b → S pole of magnet ring 22 → magnet 2
2 N pole.

(Dotted line arrow) N pole of magnet ring 22 → Main pole 24a of upper core 24 → Complementary pole 24b of upper core 24 →
S pole of magnet ring 22 → N pole of magnet ring 22
very.

(Two-dot chain arrow) N pole of magnet ring 22 → main pole 24a of upper core 24 → horizontal projection 24c of main pole 24a → S pole of magnet ring 22 → magnet ring 2
2 N pole.

In general, magnetic circuits have a lot of leakage magnetic flux and it is difficult to accurately grasp the leakage flux, but the above three are the dominant magnetic circuits. The same applies to other magnetic poles.

For the magnet 22, the armature, that is, each core 23, 2
The positional relationship in which 4 stops naturally when the power is de-energized is as shown above.
For example, the longer the lateral protrusion part 24c is, the more the magnetic path is affected, and the tip of the lateral protrusion part 24c is determined by the ratio of the attractive force generated in the magnetic circuit. It will be attracted to the south pole of 22. As a result, when the armature is energized, it rotates relative to the field pole in which the rotation angle from the armature's natural stop position is smaller, in the direction of repulsion, and in this case, the output of the motor is also large and the efficiency is also low. good.

In addition, in the case of an AC motor, when a waveform in the direction opposite to the original rotation direction is first applied, the magnetic pole center of the armature and the magnetic pole center of the field are drawn in opposite directions, and due to inertia, they shift due to a slight attraction relationship. will occur. Therefore, the condition is to prevent the inertia from going too far, and this condition is determined by the input power, the size of the load, etc.

Next, FIGS. 7 to 9 show the case where the armature core according to the present invention is applied to a DC motor used for driving a floppy disk.

An armature 30 is composed of a coil 32 concentrically wound around a bobbin 31, and a core 33 surrounding the coil 32 so that 20 magnetic poles are alternately different on the circumferential surface facing the rotor.

Note that the core 33 is formed with a main pole 33a and a complementary pole 33b. Furthermore, as shown in FIG. 9, the main pole 33a of the core 33 may be provided with a protrusion 33c that protrudes in the opposite direction of the commutative pole 33b. By doing so, the magnetic flux is concentrated at the corner. Therefore, the magnetic flux is concentrated at the tip of the commutating pole 33b and the tip of the protrusion 33c, thereby improving the efficiency of the motor. Further, the core 33 is made by combining an upper core and a lower core so as to form a closed magnetic path on the inner circumferential surface of the coil 31, and both upper and lower cores have a main pole 33a and a complementary pole 33b, respectively, and a closed magnetic path. Since the portion 33d is press-worked as one piece, its creation becomes easy.

A fixing member 34 is fitted onto the inner circumferential surface of the armature 30, and its flange portion 34a is fixed to the base plate 35, so that the armature 30 is fixed to the base plate 35.

Reference numeral 36 denotes a rotor, which includes a permanent magnet ring 37 arranged opposite to the outer circumferential surface of the armature 30 and magnetized so as to have different polarities alternately; It consists of a cup-shaped yoke 38 attached to a permanent magnet ring 37, and a shaft 40 fixed to the center of the flat side of the yoke 38 with a nut 39. The shaft 40 is inserted into a bearing 41 fitted to the inner circumferential surface of the fixed member 34, so that the rotor is rotatable.

Note that the yoke 38 has at least the permanent magnet ring 3.
It suffices if the portion that comes into contact with the circumferential surface of 7 is made of a magnetic material.

42 is a Hall element, and a permanent magnet ring 37
In order to switch the current direction of the coil 32 by the rotation of the magnetic poles of the permanent magnet ring 37, only one permanent magnet ring 37 is disposed on a printed circuit board 43 attached to the substrate 35, facing the permanent magnet ring 37.

As the rotor 36 rotates, the Hall element 42 switches the current direction of the coil 32 and the core 3
Different poles are generated alternately at each tip of the rotor 36, and the rotation of the rotor 36 is continued.
As a result, the turntable 44, which is fixed to the shaft 40 and to which a floppy disk (not shown) is fitted, is rotated.

Next, the rotational speed detection mechanism of the rotor 36 will be explained.

In FIG. 7, the periphery of the yoke 38 extends outward and is bent at a right angle, forming a bent portion 38a having a surface parallel to the printed circuit board 43.

45 is a flat permanent magnet ring serving as a power generation magnet, which is attached to the bent portion 38a;
Sixty magnetic poles are alternately magnetized on the flat side surface of the rotor 36 to have magnetic poles with a smaller pitch than the magnetic pole pitch of the rotor 36.

46 is a power generation coil, and a permanent magnet ring 45
The printed circuit board 4 is placed close to the magnetized surface of the printed circuit board 4.
3 is printed and wired. The pitch of this generating coil 46 is the same as the magnetic pole pitch of the permanent magnet ring 45.

Further, the number of poles of the armature and rotor is not limited to the above-mentioned embodiment, but 6 to 40 poles are suitable for driving a floppy disk.

In such a DC motor, since the armature coil is formed in a concentric manner, the winding work is easy, and the number of windings can be increased to improve power consumption efficiency. The number of poles can be easily changed by changing the number of branches of the core that envelops the armature, and since it is a single-phase drive, only one Hall element and its drive circuit are required to switch the current in the armature coil. This often results in a reduction in product costs.

Note that the application of the core for an armature such as a motor according to the present invention is not limited to the motor of the embodiment, but is generally applicable to rotating electric machines such as stepping motors and rotary plungers based on the same principle. Of course, it can be used widely. In this case, the commutator is omitted in the stepping motor, and
The structure is such that a permanent magnet is rotated as a rotor, and by alternately reversing the positive and negative polarities of the supplied electric power, it can be rotated at fixed angle intervals.
In this case, a pause time may be provided to completely stop each rotation to prevent synchronization. In addition, the commutator is omitted in the case of a rotary plunger, and the permanent magnet is structured to be rotatable, and a stopper for restricting rotation is provided externally so that the permanent magnet rotates within a predetermined rotation angle range. can.

As described above, according to the armature core according to the present invention, since the magnetically asymmetrical commutating pole is provided in addition to the main pole, the attraction torque between the armature and the field of the permanent magnet ring when the field is not energized is reduced. The maximum value of the torque can be made slightly larger than the required load torque, and the maximum torque generation position can be easily set to the point where the magnetic pole centers of the armature and the field coincide. Furthermore, in the case of a motor, rotational unevenness can be reduced to the minimum necessary level without reducing the efficiency of the motor.

Note that the relationship between the main pole and the complementary pole is not necessarily limited to magnetically and mechanically making a difference in size.

Although the present invention has been variously explained above with reference to preferred embodiments, the present invention is not limited to these embodiments, and it goes without saying that many modifications can be made without departing from the spirit of the invention. It is.

[Brief explanation of drawings]

Fig. 1 is a plan view of a motor to which the armature core according to the present invention is applied, Fig. 2 is a developed view of the outer peripheral surface of the armature clearly showing the armature core according to the present invention, and Fig. 3 is a non-energized motor. FIG. 4 is a developed view of the armature outer circumferential surface showing an armature core according to another embodiment; FIG. 5 is an exploded perspective view of a DC motor to which the same core is applied; Figure 6 is a perspective view of the main part with the shaft virtually extended, Figures 7 to 9 are a DC motor for a floppy disk to which the same core is applied, Figure 7 is a plan view, and Figure 8 is a diagram of the main part. A-A in Figure 7
The sectional view and FIG. 9 are developed views of the core. 1...Field, 2...Shaft, 3...Coil, 4,5
... Core, 4a, 5a... Main pole, 4b, 5b... Complementary pole,
11...Permanent magnet ring, 12...Coil, 12a...
Bobbin, 12b...Electric wire, 13...Lower core, 13a...
Disc part, 13b...Main pole, 13c...Commuting pole, 14...Upper core, 14a...Disc part, 14b...Main pole, 14c...
Commutator pole, 15... Commutator, 15a... Disc, 15
b... Commutator piece, 16... Shaft, 16a... Flange, 16b, 16c... Step portion, 17... Brush, 1
7a... Notch, 17b, 17c... Hole, 17d... Sliding portion, 18... Lead wire, 19... Case, 19a...
Recessed portion, 19b...bearing hole, 19c...engaging protrusion, 19
d...hole, 20...cover, 20a...engaging hole, 20b
...Bearing hole, 21...Shaft, 22...Permanent magnet ring, 23, 24...Core, 23a, 24a...Main pole,
23b, 24b...Commuting pole, 30...Armature, 31...Bobbin, 32...Coil, 33...Core, 33a...Main pole, 33b...Commuting pole, 33c...Protrusion, 33d...Closed magnetic path portion, 34...Fixing member, 34a ...Flange part, 3
5... Board, 36... Rotor, 37... Permanent magnet ring, 38... Yoke, 38a... Bent part, 39... Nut, 40... Shaft, 41... Bearing, 42...
Hall element, 43...Printed circuit board, 44...Turntable, 45...Permanent magnet ring, 46...Generating coil.

Claims (1)

[Claims] 1. A coil wound concentrically around the axis is bent from both end faces to the circumferential surface, with the part located on the circumferential surface serving as a magnetic pole, and the magnetic poles on one end face side and the other end face side serving as a circumferential pole. 2n (n is 2)
In a core for an armature of a motor, etc., which forms magnetic poles (natural numbers above), all or a part of the magnetic poles are divided into two in the circumferential direction to form a main pole and a commutative pole, and the armature and the field when not energized are divided into two. The position where the circumferential center point of the magnet pole or the circumferential center point between the N and S poles of the magnet pole when the magnet is at a relative stop position and the center of the armature's magnetic pole at the time of start-up energization are relative to each other. A core for an armature of a motor or the like, characterized in that the shape of the main pole or (and) the counter pole is formed magnetically asymmetrically.