JP2003079126A - Motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a motor which can generate sufficient torque and reduce vibration and noise. SOLUTION: A stepping motor 100 has a cylindrical magnet 13 comprising 2n long magnetic segments 13a which are arranged circumferentially and have widths equal to circular arc lengths corresponding to opening angles of 180/n degrees, and a coil bobbin device 19 mainly comprising an outer stator yoke 21, coils 22, and an inner stator yoke 24. The outer stator yoke 21 has n magnetic yokes which face the outside in the radial direction of the magnet 13 at positions corresponding to every other 2n pole segments 13a respectively with gaps between to constitute a magnetic circuit with the magnet 13 and the inner stator yoke 24. Each magnetic yoke has a portion whose width a is wider than a circular arc length corresponding to an opening angle of 180/n degrees and narrower than the circular arc length corresponding to an opening angle of 270/n degrees and a portion whose width c is narrower than a circular arc length corresponding to an opening angle of 90/n degrees.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor, and more particularly to a small stepping motor.

[0002]

2. Description of the Related Art A conventional stepping motor is arranged in a circumferential direction of a magnet so as to form a rotatable cylindrical magnet, and has 2n (n is a natural number of 2 or more) long magnetic pole segments and 2n. An outer stator yoke portion having n elongated magnetic pole yokes facing each other in the radial direction of the magnet with respect to every other magnetic pole segment, and a coil for exciting the stator yoke. In this stepping motor, each of the magnetic pole segments has an arc length corresponding to an opening angle of 180 / n degrees, and the magnetic pole yoke facing the magnetic pole segment has an arc length corresponding to an opening angle of 90 / n degrees (for example, , JP-A-11
-0559929).

[0003]

However, in the conventional stepping motor, since the width of the magnetic pole yoke is only about 1/2 of the width of the magnetic pole segment, the effective magnetic force of the magnet is hindered by the increase of the leakage magnetic flux, and It has the drawback that sufficient torque cannot be obtained and vibration and noise are generated due to an increase in detent torque.

An object of the present invention is to provide a motor capable of obtaining sufficient torque and reducing vibration and noise.

[0005]

In order to achieve the above object, a motor according to claim 1 is arranged in the circumferential direction of the magnet so as to form a rotatable cylindrical magnet, and has a width. 2n (n is a natural number greater than or equal to 2) long magnetic pole segments, which are arc lengths corresponding to an opening angle of 180 / n degrees, and every other 2n magnetic pole segments and a gap radially outside the magnet. In a motor including an outer stator yoke portion having n elongated magnetic pole yokes that face each other via a coil and a coil that excites the outer stator yoke portion, each of the magnetic pole yokes has an opening angle of 180 / n. A part wider than the arc length corresponding to the degree and an opening angle of 1
And a portion narrower than the arc length corresponding to 80 / n degrees.

According to a second aspect of the present invention, in the motor according to the first aspect, the portion where the width is narrower than the arc length corresponding to the opening angle of 180 / n degrees is the portion where the width is narrower than the arc length corresponding to the opening angle of 90 / n degrees. It is characterized by including.

The motor according to claim 3 is the motor according to claim 1 or 2.
In the motor described above, the part where the width is wider than the arc length corresponding to the opening angle of 180 / n degrees includes a part where the width is wider than the arc length corresponding to the opening angle of 180 / n degrees and narrower than the arc angle corresponding to the opening angle of 270 / n degrees. Is characterized by.

The motor according to claim 4 is the motor according to any one of claims 1 to 3.
In the motor according to any one of claims 1 to 5, an area of one facing portion of the magnetic pole yoke facing one of the magnetic pole segments is equal to an area of a portion of the magnetic pole segment having the same length as the facing portion. It is characterized by

The motor according to claim 5 is the motor according to any one of claims 1 to 4.
In the motor according to any one of items 1 to 3, the outer stator yoke portions are arranged to face each other in a thrust direction of the magnet, and are arranged radially outward of the magnet with respect to every other one of the 2n magnetic pole segments. The motor further comprises two outer stator yokes each having n elongated outer magnetic pole yokes facing each other with a gap, and the motor is further arranged to face each other in the thrust direction of the magnet and is radially inward of the magnet. Two inner stator yokes each having a single elongated inner magnetic pole yoke facing each other with a gap therebetween, the coil being wound around the inner stator yoke, and the outer stator yoke and the inner stator. It is characterized by comprising two coils for exciting the yoke.

According to a sixth aspect of the present invention, there is provided a motor according to the first aspect.
The motor according to any one of items 1 to 3 is a stepping motor.

[0011]

DETAILED DESCRIPTION OF THE INVENTION A motor according to an embodiment of the present invention will be described in detail below with reference to the drawings.

FIG. 1 shows a motor according to an embodiment of the present invention.
In particular, it is an exploded perspective view of a stepping motor.

In FIG. 1, a stepping motor 100
Has a central shaft 10, and further has a connecting ring 11 as a supporting member that serves as a cover of the motor, an intermediate ring 12 fitted in the connecting ring 11, and a cylindrical shape housed in the intermediate ring 12. The magnet 13 and the rotating shaft 14 that rotatably supports the magnet 13. The magnets 13 are arranged in the circumferential direction and have a width of 2n (n) which is an arc length corresponding to an opening angle of 180 / n degrees.
Is a natural number of 2 or more, and in the present embodiment, n = 5) long magnetic pole segments 13a (FIGS. 4 to 6).

The stepping motor 100 also has a mounting board 17 for supporting the tip bearing 15 at one end and positioning and supporting the coil bobbin device 16 at the other end.

The tip of the rotating shaft 14 is supported by a tip bearing 15, and the rear end of the rotating shaft 14 supports a coil bobbin device 19 shown in FIG.

The intermediate ring 12 sets the facing angle of the outer stator yoke 21 described later to 360 / (n × 4) (n = 5 in this embodiment) and positions the coil 22 described later. The connecting ring 11 is the outer stator yoke 2
Position and fix 1.

FIG. 2 is a coil bobbin device 1 shown in FIG.
9 is an exploded perspective view of FIG.

In FIG. 2, the coil bobbin device 19 is
It mainly includes an outer stator yoke 21, a coil bobbin 23 around which a coil 22 is wound, and an inner stator yoke 24 fitted in the coil bobbin 23.

The outer stator yoke 21 is made of a soft magnetic material and is opposed to every other 2n magnetic pole segments 13a radially outward of the magnet 13 with a gap n (n = n in the present embodiment). 5) Number of magnetic pole yokes 21
a, and forms a magnetic circuit in cooperation with the magnet 13 and the inner stator yoke 24 (FIGS. 4 to 6).

The inner stator yoke 24 is made of a soft magnetic material and has a single magnetic pole yoke 24a which faces the magnet 13 inward in the radial direction with a gap.
3 and the outer stator yoke 21 cooperate with each other to form a magnetic circuit.

The coil bobbin device 16 includes a mounting board 17
Mainly includes an outer stator yoke 25 fixed to the other end of the coil bobbin, a coil bobbin 27 around which a coil 26 is wound, and an inner stator yoke 28 internally fitted to the coil bobbin 27. It has the same configuration as.

Further, the rear end bearing 18 is pressed in the thrust direction by a thrust spring 30 supported by a cap 29 provided on the inner stator yoke 24, and as a result, the rotary shaft 14 is also biased in the thrust direction.

FIG. 3 is a partial plan view of the magnet 13 and the outer stator yoke 21 in FIG. Also, FIG.
Sectional views regarding each of the cutting lines IV-IV, VV, and VI-VI are shown in FIGS. 4, 5, and 6, respectively.

In FIG. 3, 1 of the outer stator yoke 21
One magnetic pole yoke 21a has a facing portion 21b facing the magnet 13 radially outward of the magnet 13 with a gap. The facing portion 21b has a magnetic pole yoke 21 at its root portion (corresponding to the position of the cutting line IV-IV).
The width a of a is wider than the arc length corresponding to the opening angle of 180 / n degrees and narrower than the arc length corresponding to the opening angle of 270 / n degrees (FIG. 4), and in the middle portion (corresponding to the cutting line V-V position) of the magnetic pole yoke 21. Is the arc length corresponding to an opening angle of 180 / n degrees (Fig. 5),
At the tip (corresponding to the position of the cutting line VI-VI), the width c of the magnetic pole yoke 21 is narrower than the arc length corresponding to the opening angle of 90 / n degrees (FIG. 6). Here, at the position of the intermediate portion (corresponding to the cutting line VV position), the width of the magnetic pole segment 13a and the width b of the magnetic pole yoke 21a are equal, and the area of the facing portion 21b and the length of the facing portion 21b are the same length. The areas of the magnetic pole segments 13a (hatched portions in FIG. 3) are equal.

Here, the open angle is a central angle corresponding to the width a of the magnetic pole yoke 21a, and is indicated by θ in FIG. 4, for example.

In the above structure, when the coil 22 is energized, the outer stator yoke 21 and the inner stator yoke 24 are excited to be attracted to the magnetic poles (N, S) and the magnet 1
Magnet 1 (N, S) repels and attracts magnetized magnetic poles, and magnet 1
The magnet rotor composed of 3 and the rotating shaft 14 rotates and moves according to the energization of the coil. Along with the rotational movement of the magnet rotor, the magnetic pole yoke 21a generates detent torque. The detent torque is a torque that is generated between the magnetic poles of the magnetic pole yokes 21 a that are not energized and is not excited and the magnetized magnetic pole of the magnet 13, and is attracted (repulsed) to the magnetized magnetic pole of the magnet 13 and is stable. Try to stay in position. This detent torque is applied to the magnet 13
Increase due to magnetic flux deviation due to leakage flux of
It causes an increase in noise.

In this embodiment, the effect described with reference to FIG.

FIG. 7 is a graph showing the relationship between the detent torque generated by the magnetic pole yoke 21a and the rotation angle of the magnet rotor.

The detent torque generated by the magnetic yoke 21a has the characteristic q when the width of the magnetic pole yoke 21a is the width a or the width b, and has the characteristic r when the width is the width c.

The characteristics q and r have the same phase and opposite polarities.

According to the present embodiment, the detent torques in the width a and width b portions and the width c portion cancel each other out, and as a result, the magnetic pole yoke 21a operates so as to reduce the detent torque. In addition, the inner stator yoke 2
Since the four magnetic pole yokes are single, the magnetic flux is not biased with the magnet 13, the leakage magnetic flux can be further reduced, and the generation of detent torque can be prevented.

The width a and the width b are the same as those of the magnetic pole segment 1.
Since the width of 3a is equal to or larger than the width, more magnetic flux can be effectively used. The area of the facing portion 21b is equal to that of the facing portion 21b.
Is equal to the area d (hatched portion in FIG. 3) of the magnetic pole segment 13a having the same length as that of the magnetic pole yoke 21a.
Operates so as to more effectively use the magnetic flux of the magnetic pole segments 13a of the magnets facing each other in the radial direction, as in the case where the width from the root to the tip is the width b, and a larger torque can be obtained. .

In this embodiment, the outer stator yoke 25 has the same structure as the outer stator yoke 21, the inner stator yoke 28 has the same structure as the inner stator yoke 24, and the coil 26 has the same structure as the coil 22.

[0034]

As described in detail above, according to the motor of the first aspect, the magnetic pole yoke has an opening angle of 180 /
A part wider than the arc length corresponding to n degrees and an opening angle of 180 / n
Since it has a portion that is narrower than the arc-corresponding arc length, it is possible to effectively use the magnetic flux of the magnetic pole segment of the magnet to reduce the detent torque, so that a sufficient torque can be obtained and vibration and noise can be reduced. be able to.

According to the motor of the second aspect, since the magnetic pole yoke has a portion whose width is narrower than the arc length corresponding to the opening angle of 90 / n degrees, the width is near the arc angle corresponding to the opening angle of 180 / n degrees. The detent torque at this time can be reliably reduced.

According to another aspect of the motor of the present invention, since the magnetic pole yoke has a portion whose width is larger than the arc length corresponding to the opening angle of 180 / n degrees and smaller than the arc length corresponding to the opening angle of 270 / n degrees, the width of the stator yoke. Can reliably reduce the detent torque in a portion narrower than the arc length corresponding to the opening angle of 90 / n degrees.

According to another aspect of the motor of the present invention, the area of one facing portion of the magnetic pole yoke facing one of the magnetic pole segments is equal to the area of the portion of the magnetic pole segment having the same length as the facing portion. The magnetic pole yoke can more effectively utilize the magnetic flux of the magnetic pole segments facing each other in the radial direction.

According to the motor of claim 5, the motor has two outer stator yokes each having n magnetic pole yokes, two inner stator yokes each having a single magnetic pole yoke, and an outer stator yoke. Since it is composed of two coils for exciting the inner stator yoke, it is possible to eliminate the leakage magnetic flux with the magnet, thereby further reducing the detent torque.

[Brief description of drawings]

FIG. 1 is an exploded perspective view of a motor according to an embodiment of the present invention.

FIG. 2 is an exploded perspective view of a coil bobbin device 19 shown in FIG.

3 is a partial plan view of a magnet 13 and an outer stator yoke 21 in FIG.

4 is a cross-sectional view taken along the line IV-IV of FIG.

5 is a cross-sectional view taken along the line VV of FIG.

6 is a cross-sectional view taken along line VI-VI of FIG.

FIG. 7 is a graph showing the relationship between the detent torque generated by the magnetic pole yoke 21a and the rotation angle of the magnet rotor.

[Explanation of symbols]

13 magnets 13a magnetic pole segment 21 Outer stator yoke 21a Magnetic pole yoke 22 coils 24 Inner stator yoke 24a magnetic pole yoke 25 Outer stator yoke 26 coils 28 Inner stator yoke 100 stepping motor a, b, c Magnetic pole yoke width

Claims (6)

[Claims] 1. A number of 2n (n is a natural number of 2 or more) arranged in the circumferential direction of the magnet to form a rotatable cylindrical magnet and having an arc length corresponding to an opening angle of 180 / n degrees. A long magnetic pole segment, and an outer stator yoke portion having n long magnetic pole yokes, which are opposed to every other 2n magnetic pole segments radially outward of the magnet with a gap. In a motor including a coil for exciting the outer stator yoke portion, each of the magnetic pole yokes has a portion having a width wider than an arc length corresponding to an opening angle of 180 / n degrees and a width having an arc length corresponding to an opening angle of 180 / n degrees. A motor having a narrower portion. 2. The motor according to claim 1, wherein the portion whose width is narrower than the arc length corresponding to an opening angle of 180 / n degrees includes a portion whose width is narrower than the arc length corresponding to an opening angle of 90 / n degrees. 3. The portion whose width is wider than the arc length corresponding to an open angle of 180 / n degrees includes a portion whose width is wider than the arc length corresponding to an open angle of 180 / n degrees and narrower than the arc length corresponding to an open angle of 270 / n degrees. The motor according to claim 1 or 2, characterized in that: 4. The area of one facing portion of the magnetic pole yoke facing one of the magnetic pole segments is equal to the area of a portion of the magnetic pole segment having the same length as the length of the facing portion. The motor according to any one of items 1 to 3. 5. The outer stator yoke portion is disposed to face the thrust direction of the magnet, and the 2n
The motor further comprises two outer stator yokes each having n elongated outer magnetic pole yokes that face each other with respect to every other magnetic pole segment in a radial direction outside the magnet with a gap therebetween. The magnet includes two inner stator yokes that are arranged to face each other in the thrust direction of the magnet and that have a single elongated inner magnetic pole yoke that faces each other in the radial direction of the magnet with a gap therebetween. The motor according to any one of claims 1 to 4, wherein the motor is wound around an inner stator yoke and includes two coils, which are the outer stator yoke and the coil which excites the inner stator yoke. 6. The motor according to claim 1, wherein the motor is a stepping motor.