JP2000197335A - Stepping motor - Google Patents

Abstract

(57) [Problem] To effectively reduce noise and vibration of a hybrid type stepping motor provided with a square stator. In a cross-sectional shape of a stator core, a line connecting centers of sides facing each other in a vertical direction is a Y axis (a direction of antinode of primary natural vibration of the stator core), and a center of each side facing each other in a left-right direction. The X-axis (the direction of the antinode of the primary natural vibration of the stator core) is connected to each other, one of the diagonal lines is the M-axis (the direction of the antinode of the secondary natural vibration of the stator core), and the other is the N-axis (the direction of the antinode of the secondary natural vibration of the stator core). , The magnetic poles A1, B1, C1, A2
The positions of all the columns 2 of B2 and C2 are displaced in the circumferential direction from the X axis, Y axis, M axis and N axis, and the small teeth 3 are arranged at equal intervals in the circumferential direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stepping motor having a rectangular stator, and more particularly to a hybrid type stepping motor used for an ink jet printer, a scanner or the like.

[0002]

2. Description of the Related Art As a conventional hybrid stepping motor of this type, for example, the one shown in FIGS. 5 to 7 is known.

The stepping motor 1 has a three-phase six-pole stator 6, a pair of brackets 7 a and 7 b respectively fitted to both ends in the axial direction of the stator 6, and is inserted into the inner peripheral side of the stator 6. And a rotor 9 rotatably supported by bracket pairs 7a, 7b via bearings 8a, 8b.

The stator 6 has a stator core 4 having a substantially square cross-sectional outer shape. Six magnetic poles A 1, B comprising a support 2 and small teeth 3 are provided on the inner periphery of the stator core 4.
1, C1, A2, B2, and C2 are provided at equal intervals in the circumferential direction. The magnetic poles A1, B1, C1, A2, B
2, C2, the winding 5 is wound.

The rotor 9 includes a rotating shaft 10, a disk-shaped permanent magnet 11 fixed to the rotating shaft 10, and a gear-shaped rotor core 12 fixed to both axial ends of the permanent magnet 11.
a, 12b. Rotor core 12a
Are shifted in the circumferential direction by a half pitch with respect to the rotor core 12b, and therefore, the tooth poles (not shown) of the rotor core 12b are located between the adjacent tooth poles (not shown) of the rotor core 12a. It has become. In the figure, reference numeral 15 denotes a bracket pair 7a, 7b
It is a bolt for fixing.

[0006]

It is well known that a hybrid type stepping motor is a loud noise and a lot of vibration. However, a technique for effectively reducing such noise and vibration is not yet known. The fact is that it has not been proposed.

The inventors of the present invention have analyzed the causes of noise and vibration of a hybrid type stepping motor having a rectangular stator, and have obtained the following findings.

That is, in a standard hybrid type stepping motor having an air gap of 50 μm, the suction / repulsive force (excitation force) between the stator 6 and the rotor 9 in the radial direction exceeds 1 with respect to the generated torque 1, and the shaft The analysis found that the force in the direction was about 0.1.

In the cross-sectional shape of the rectangular stator core 4, as shown in FIG. 7, a line connecting the centers of the sides facing each other in the vertical direction is the Y axis, and the centers of the sides facing each other in the horizontal direction are the same. Is the X axis, and one of the diagonal lines is M
When the other axis is the N axis, the primary vibration
8 Hz) is antinode in the X and Y axis directions (see FIG. 8), and the secondary (6188 Hz) of natural vibration is antinode in the M and N axis directions (see FIG. 9).
It has been found by actual measurement and analysis that this is the most problematic frequency range below 10 kHz in terms of hearing.

[0010] The primary and secondary natural vibrations of the stator core 4 occupy most of the causes of the hybrid type stepping motor having large vibrations and large noises, and a large radial excitation force (air gap) on the stator 6 described above. Is extremely small.) When the same frequency component as the primary and secondary natural vibrations directly acts in the direction of the antinode of the primary and secondary natural vibrations, resonance occurs. We have learned that harsh noise and vibration are generated. By the way, in the case of the conventional stator core 4 shown in FIG. 7, the strut 2 is arranged on the Y-axis, so that a large radial exciting force on the stator 6 is directly applied to the antinode of the primary natural vibration of the stator core 4. This will generate noise and vibration.

The present invention has been made on the basis of such knowledge, and is designed to reduce noise and vibration by preventing the radial excitation force on the stator from directly acting on the antinodes of the primary and secondary natural vibrations of the stator core. It is an object of the present invention to provide a stepping motor capable of effectively reducing power consumption.

[0012]

In order to achieve the above object, a stepping motor according to a first aspect of the present invention has a plurality of magnetic poles having a substantially square cross section and having a column and small teeth on an inner peripheral portion. A stator core provided at predetermined intervals in the circumferential direction, and a stator having windings wound around the magnetic poles, a pair of brackets respectively attached to both axial ends of the stator, A rotor inserted into the inner peripheral side and rotatably supported via a bearing, in the cross-sectional shape of the stator core, a line connecting the centers of the sides facing each other in the up-down direction. When the line connecting the centers of the sides facing each other in the Y axis and the left and right directions is the X axis, one of the diagonal lines is the M axis, and the other is the N axis, the position of all the columns of the plurality of magnetic poles is the X axis. , Y axis, While positioned off the axis and N axis in the circumferential direction, characterized in that a said small teeth in the circumferential direction at equal intervals.

According to this means, a large radial excitation force having the same frequency component as the primary and secondary natural vibrations of the stator core is prevented from being directly applied to the antinodes of the primary and secondary natural vibrations. Can be.

According to a second aspect of the present invention, in the stepping motor according to the first aspect, the stator has three phases and six poles.

According to a third aspect of the present invention, in the stepping motor according to the first aspect, the stator has two phases and eight poles.

According to a fourth aspect of the present invention, there is provided a stepping motor according to any one of the first to third aspects, wherein
The arrangement is characterized by being arranged at a distance of 22.5 ° in the circumferential direction from at least one of the axis, the Y axis, the M axis and the N axis.

According to this means, the pole of the magnetic pole is set to the X-axis and Y-axis.
It is possible to reduce the excitation force applied in the direction of antinodes of the primary and secondary natural vibrations by arranging at the position farthest from at least one of the axes M, M and N.

When the stator has two phases and eight poles, all the poles of each magnetic pole are arranged at a position deviated from the X, Y, M, and N axes by 22.5 ° in the circumferential direction, and as a whole, Each strut can be evenly arranged at the position farthest from the X, Y, M and N axes, so that the sum of the excitation forces applied in the antinode directions of the primary and secondary natural vibrations is minimized. It becomes possible to do.

According to a fifth aspect of the present invention, in the stepping motor according to the second aspect, the pair of the stepping motors are located at a position deviated by 22.5 ° in a circumferential direction from any one of the X axis, the Y axis, the M axis, and the N axis. The supports are arranged 180 degrees apart from each other in the circumferential direction, and this is used as a reference support, and the angle between the other support and the reference support adjacent to each other on both sides in the circumferential direction of the reference support is 45 °.
The angle is set as close to 45 ° as possible, provided that the winding space can be ensured in a range exceeding the range.

According to this means, even when the small teeth of the three-phase six-pole stator are arranged at equal intervals in the circumferential direction,
Each pillar can be arranged at a position farthest from the X-axis, the Y-axis, the M-axis, and the N-axis as a whole as long as the winding space of all magnetic poles can be secured.

[0021]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a plan view showing a stator core of a hybrid stepping motor according to a first embodiment of the present invention, FIG. 2 is a plan view showing a modification of the stator core, and FIG. 3 is a second embodiment of the present invention. FIG. 4 is a plan view illustrating a stator core of a hybrid stepping motor according to a second embodiment of the present invention. FIG. 4 is a plan view illustrating a stator core of the hybrid stepping motor according to a second embodiment of the present invention.
FIG. 5 is an overall perspective view of a hybrid stepping motor shared by the embodiments, and FIG. 6 is a cross-sectional view of the hybrid stepping motor shared by the embodiments.
In each of the embodiments, since the configuration of the portion excluding the stator is the same as that of the conventional hybrid type stepping motor 1 shown in FIGS. 5 and 6, the portions overlapping with FIG. 5 and FIG. Will be described with the same reference numerals.

First, a description will be given of a hybrid type stepping motor 100 according to a first embodiment of the present invention.
A three-phase six-pole stator 106 and a pair of brackets 7 fitted to both ends of the stator 106 in the axial direction, respectively.
a, 7b, and a rotor 9 inserted into the inner peripheral side of the stator 106 and rotatably supported by the bracket pairs 7a, 7b via bearings 8a, 8b.

As shown in FIG. 1, the stator 106 is provided with a stator core 104 having a substantially square cross-section, and has six magnetic poles formed on the inner periphery of the stator core 104. A1, B1, C1, A2, B
2, C2 are provided at equal intervals in the circumferential direction. Small teeth 3
Is constituted by a plurality of small teeth 3a. In this embodiment, the column 2 is disposed at the center of the small teeth 3 in the circumferential direction.
A winding 5 is wound around the column 2. Further, bolt insertion holes 104a are formed at four corners of the stator core 104.

The rotor 9 includes a rotating shaft 10, a disk-shaped permanent magnet 11 fixed to the rotating shaft 10, and a gear-shaped rotor core 12 fixed to both axial ends of the permanent magnet 11.
a, 12b. Rotor core 12a
Are shifted in the circumferential direction by a half pitch with respect to the rotor core 12b, and therefore, the tooth poles (not shown) of the rotor core 12b are located between the adjacent tooth poles (not shown) of the rotor core 12a. It has become. The air gap between the rotor cores 12a and 12b and the stator 106 is usually set to be extremely small, about 50 to 100 μm, so that a large torque can be obtained.

At four corners of the bracket 7a, bolt insertion holes 1 are provided.
07a are formed concentrically with the bolt insertion holes 104a of the stator core 104, and screw holes 10 are formed at four corners of the bracket 7b.
7b is formed concentrically with the bolt insertion hole 104a,
By screwing the fixing bolt 15 inserted into the bolt insertion holes 104a and 107a into the screw hole 107b, the bracket pair 7a, 7b is fixed to the stator 106.

In this embodiment, in the cross-sectional shape of the rectangular stator core 104, the line connecting the centers of the sides facing each other in the vertical direction is the Y axis, and the center of the sides facing each other in the horizontal direction is the center. , The column 2 of the magnetic pole A1 is disposed at a position deviated by 22.5 ° in the circumferential direction from the Y axis, when one of the diagonal lines is the M axis and the other is the N axis,
The columns 2 of the remaining magnetic poles B1, C1, A2, B2, C2 are arranged at regular intervals at a pitch of 60 °.

Thus, each of the magnetic poles A1, B1, C1, A
All the columns 2, B 2, and C 2 are circumferentially deviated from the X axis and the Y axis, which are the antinodes of the primary natural vibration of the stator core 104, and the M axis and the N axis, which are the antinodes of the secondary natural vibration. The small teeth 3 are also arranged at equal intervals in the circumferential direction since the columns 2 are located at the center of the small teeth 3 in the circumferential direction.

As described above, in this embodiment, each magnetic pole A
All the columns 2 of 1, 1, B1, C1, A2, B2, and C2 have the X axis and the Y axis that are the directions of the antinode of the primary natural vibration of the stator core 104, and the M axis and the N that are the directions of the antinode of the secondary natural vibration. Since it is arranged in the circumferential direction from the axis, a large radial excitation force of the same frequency component as the primary and secondary natural vibrations should not be applied directly to the antinodes of the primary and secondary natural vibrations. As a result, it is possible to effectively reduce the most unpleasant noise and vibration in terms of audibility at 10 kHz or less.

In this embodiment, the hybrid type stepping motor 100 having a three-phase six-pole stator 106 is taken as an example. However, a hybrid type stepping motor 100 having a two-phase eight-pole stator 206 is used instead. The present invention may be applied to the stepping motor 200.

As shown in FIG. 2, the stator 206 is provided with a stator core 204 having a substantially square cross section, and has eight magnetic poles including a support 2 and small teeth 3 on the inner periphery of the stator core 204. A1, B1, A2, B2, A
3, B3, A4, and B4 are provided at equal intervals in the circumferential direction. In this embodiment, the column 2 is disposed at the center in the circumferential direction of the small tooth portion 3, and the winding 5 is wound around the column 2.

In this embodiment, the column 2 of the magnetic pole A1 is arranged at a position deviated from the Y axis by 22.5 ° in the circumferential direction, and the remaining magnetic poles B1, A2, B2, A3, B3, A
4 and B4 columns 2 are arranged at equal intervals at a 45 ° pitch.

Thus, each of the magnetic poles A1, B1, A2, B
All the columns 2 of A2, A3, B3, A4, and B4 have the X axis and the Y
Axis and the antinodes of the secondary natural vibrations are arranged in the circumferential direction from the M-axis and the N-axis, and each strut is located at the center of the small tooth portion 3 in the circumferential direction. The teeth 3 are also arranged at equal intervals in the circumferential direction.

As described above, in this embodiment, each magnetic pole A
All the columns 2 of B1, A2, B2, A3, B3, A4, and B4 are the X axis and the Y axis, which are the directions of the antinode of the primary natural vibration of the stator core 204, and the directions of the antinode of the secondary natural vibration. Since it is arranged circumferentially deviated from the M-axis and N-axis, a large radial excitation force of the same frequency component as the primary and secondary natural vibrations is directly applied to the antinodes of the primary and secondary natural vibrations. And all the columns 2 are circumferentially separated from the X, Y, M and N axes by 2
Since the columns 2 are arranged at positions deviated from each other by 2.5 °, the columns 2 as a whole can be evenly arranged at the positions farthest from the X axis, the Y axis, the M axis, and the N axis. It is possible to minimize the sum of the exciting forces applied in the direction of the antinode of the next natural vibration, and it is possible to more effectively reduce harsh noise and vibration of 10 kHz or less.

Next, a description will be given of a hybrid type stepping motor 300 according to a second embodiment of the present invention. The configuration of the hybrid type stepping motor 300 other than the stator is the same as that of the above-described first embodiment, and therefore, only the portions different from the first embodiment will be described.

Referring to FIGS. 4 and 6, the stator 306 of this hybrid type stepping motor 300 has three phases and six poles. And six magnetic poles A 1, B 1, C 1, A 2, B 2, C 2 comprising the small teeth 3 are provided at predetermined intervals in the circumferential direction.

By the way, in the case of the three-phase six-pole stator 306, similarly to the above-described two-phase eight-pole stator 206, each of the columns 2 is generally moved from the X axis, the Y axis, the M axis, and the N axis. It is most preferable from the standpoint of vibration reduction to arrange at the farthest position to reduce the sum of the exciting forces applied in the antinode directions of the primary and secondary natural vibrations.

Specifically, for example, as shown in FIG.
The magnetic poles B1 and B
The two columns (reference columns) 2 are arranged 180 ° apart from each other, and the column 2 of the magnetic pole A1 and the column 2 of the magnetic pole C1 are arranged at ± 45 ° from the column 2 of the magnetic pole B1, respectively. By arranging the column 2 of the magnetic pole C2 and the column 2 of the magnetic pole A2 at positions of ± 45 ° from the column 2, all columns 2 are moved 22.5 circumferentially from the X, Y, M, and N axes. It is conceivable to arrange the columns 2 at positions farthest from the X-axis, Y-axis, M-axis and N-axis as a whole.

In this case, each magnetic pole A1, B1, C1, A
The support columns 2 of B2, C2, and C2 are not arranged at equal intervals in the circumferential direction. Therefore, the arrangement of the small teeth 3a of the small tooth portions 3 with respect to the support column 2 is asymmetrical except for the magnetic poles B1 and B2. The small teeth 3 of the magnetic poles A1, B1, C1, A2, B2, C2 are arranged at equal intervals in the circumferential direction.

The small teeth 3 are arranged at equal intervals in the circumferential direction. When two-phase excitation is performed with three phases and six poles, A1B1 (A2
B2) → B1C1 (B2C2) → C1A1 (C2A2)
In order to excite the rotor 9 by switching the magnetic poles in the following order, the small teeth 3 are arranged at equal intervals in the circumferential direction to balance the magnetic attraction / repulsion in the radial direction with respect to the rotor 9. This is because a radially symmetrical force is applied, so that unnecessary vibrations are not induced in the rotor 9.

However, as shown in FIG.
Axis, Y axis, M axis and N axis at a position deviated by 22.5 ° in the circumferential direction, and as a whole, each column 2 is X axis, Y axis, M axis
When the small teeth 3 are arranged at the positions farthest from the axis and the N-axis and the small teeth 3 are arranged at equal intervals in the circumferential direction, as shown in FIG. 3, the magnetic poles A1, C1, A
2 and C2, the column 2 is located at the end in the circumferential direction of the small tooth portion 3, and a problem arises that a space for winding the coil cannot be secured.

Therefore, in this embodiment, as shown in FIG. 4, ± 55 ° from the support 2 of the magnetic pole B1 as the reference support.
, The support 2 of the magnetic pole A1 and the support 2 of the magnetic pole C1 are arranged, and the support 2 of the magnetic pole C2 and the support 2 of the magnetic pole A2 are arranged at ± 55 ° from the support 2 of the magnetic pole B2 as the reference support. Thus, even when the small teeth 3 are arranged at equal intervals in the circumferential direction, the winding space for all the magnetic poles A1, B1, C1, A2, B2, and C2 is ensured, Each column 2 is arranged at a position farthest from the X-axis, Y-axis, M-axis and N-axis as a whole as long as the winding space can be secured.

As described above, in this embodiment, each magnetic pole A
All the columns 2 of 1, B1, C1, A2, B2, and C2 have the X axis and the Y axis that are the antinodes of the primary natural vibration of the stator core 304, and the M axis and the N that are the antinodes of the secondary natural vibration. Since it is arranged in the circumferential direction from the axis, a large radial excitation force of the same frequency component as the primary and secondary natural vibrations should not be applied directly to the antinodes of the primary and secondary natural vibrations. And all the magnetic poles A1,
Since the columns 2 are arranged at positions farthest from the X-axis, Y-axis, M-axis, and N-axis as a whole as long as the winding space of B1, C1, A2, B2, and C2 can be secured, the first The effect of reducing noise and vibration can be further enhanced as compared with the embodiment.

[0044]

As is apparent from the above description, according to the present invention, the radial exciting force applied to the stator does not directly act on the antinodes of the primary and secondary natural vibrations of the stator core. Therefore, an effect that noise and vibration can be effectively reduced can be obtained.

[Brief description of the drawings]

FIG. 1 is a plan view showing a stator core of a hybrid type stepping motor according to a first embodiment of the present invention.

FIG. 2 is a plan view showing a modified example of a stator core.

FIG. 3 is a plan view used for describing a stator core of a hybrid type stepping motor according to a second embodiment of the present invention.

FIG. 4 is a plan view showing a stator core of a hybrid stepping motor according to a second embodiment of the present invention.

FIG. 5 is an overall perspective view of a hybrid stepping motor commonly used in the conventional example and each embodiment.

FIG. 6 is a cross-sectional view of a hybrid stepping motor commonly used in a conventional example and each embodiment.

FIG. 7 is a plan view showing a stator core of a conventional hybrid type stepping motor.

FIG. 8 is a schematic diagram showing a mode of primary natural vibration of a stator core.

FIG. 9 is a schematic diagram illustrating modes of secondary natural vibration of the stator core.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 2 ... Support | pillar 3 ... Small tooth part 5 ... Winding 7a, 7b ... A pair of brackets 8a, 8b ... Bearing 9 ... Rotor 10 ... Rotating shaft 11 ... Permanent magnet 12a, 12b ... Rotor core 100, 200, 300 ... Hybrid type stepping motor 104, 204, 304 ... stator core 106, 206, 306 ... stator

Claims (5)

[Claims] 1. A stator core having a substantially square cross-section and having a plurality of magnetic poles formed on an inner peripheral portion thereof and comprising a column and small teeth, provided at predetermined intervals in a circumferential direction, and wound around the magnetic poles. A stator having windings, a pair of brackets attached to both ends of the stator in the axial direction, and a rotor inserted on the inner peripheral side of the stator and rotatably supported via bearings. In the cross-sectional shape of the stator core, a line connecting the centers of the sides facing each other in the vertical direction is the Y axis, a line connecting the centers of the sides facing each other in the horizontal direction is the X axis, When one of the diagonal lines is the M axis and the other is the N axis, the positions of all the poles of the plurality of magnetic poles are circumferentially offset from the X, Y, M, and N axes, and Tooth parts arranged at equal intervals in the circumferential direction Stepping motor characterized in that: 2. The stepping motor according to claim 1, wherein said stator has three phases and six poles. 3. The stepping motor according to claim 1, wherein the stator has two phases and eight poles. 4. The X-axis, Y-axis, M-axis and N
The stepping motor according to any one of claims 1 to 3, wherein the stepping motor is disposed at a position deviated from at least one of the shafts by 22.5 degrees in a circumferential direction. 5. A pair of pillars are disposed at a position deviated by 22.5 ° in the circumferential direction from any one of the X-axis, Y-axis, M-axis, and N-axis, and are spaced apart by 180 ° in the circumferential direction from each other. With this as the reference support, the angle between the other support and the reference support adjacent to each other on both sides in the circumferential direction of the reference support, provided that the winding space can be secured in a range exceeding 45 °, 3. The stepping motor according to claim 2, wherein the angle is set as close to 45 [deg.] As possible.