JPH10108448A - Stepping motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce noise by preventing contact between a cup-type or dish-type frame yoke section and a circular yoke or vibration of winding in an excitation coil. SOLUTION: This motor is provided with a rotor 10, consisting of a multipole magnetized permanent magnet, two pairs of yoke units 8, 8 providing a couple of circular yokes 6, 6 having a plurality of interdigital poles 6a in the circumference direction with an excitation coil 3, held in combination therebetween on the same shaft as the rotor and a frame yoke 2, formed to surround the excitation coil 3 and circular yokes 6, 6. A gap between the circular yokes 6, 6 and frame yoke 2 is filled with a filler 20, such as synthetic resin or rubber. It is preferable that a gap formed between the internal wall of the groove formed at the external circumference of bobbin of the excitation coil 3 and the internal wall of the frame yoke 2 be also filled with a filler.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stepping motor, and more specifically, to a rotor having a multipole-magnetized permanent magnet and a plurality of comb-shaped poles in a circumferential direction. A stator yoke portion formed by combining a plurality of annular yoke portions with each other, an excitation coil mounted around the comb-shaped pole portion of the stator yoke portion, and formed so as to surround the excitation coil and the stator yoke portion. The present invention relates to a stepping motor provided with a frame yoke portion.

[0002]

2. Description of the Related Art As shown in FIGS. 6 and 7, for example, a generally known stepping motor includes a frame-shaped yoke 2 formed in a cup shape. Two sets of yoke units 8 are inserted between two annular yoke pieces 6-6 each having a portion 6a and sandwiching the exciting coil 3 wound around the bobbin 4, and the cylindrical portion is multipolarly magnetized. The rotor 10 made of permanent magnets is inserted into two sets of yoke units 8-8 in the cup-shaped frame yoke 2, and one of the shafts 10a is externally connected to the bearing 14a of the cup-shaped frame yoke 2. To protrude. Next, the lid member 12 is assembled by closing the lid member 12 over the opening of the cup-shaped frame yoke body 2 with the other shaft portion 10b of the rotor rotor 10 protruding from the central bearing portion 14b of the lid member 12. .

In the stepping motor having such a configuration, when the rotor rotor 10 is driven to rotate, one of the upper and lower excitation coils 3 is energized, and the annular yoke pieces 6-6 surrounding the excitation coil 3 and the cup-shaped frame yoke body. 2, a magnetic pole is formed on the comb-shaped pole portion 6a of the annular yoke piece 6-6. As a result, a magnetic repulsive force or an attractive force is generated between the magnetic pole of the comb tooth-shaped pole portion 6a and the magnetic pole on the outer periphery of the rotor rotor 10, and the rotor rotor 10 is brought into contact with the annular yoke piece 6 of the stator. -6 is driven to rotate by a predetermined step angle relative to -6. In order to further rotate the rotor 10, one of the energized exciting coils 3 is cut off and the other energized coil 3 is energized. A magnetic pole is generated in the tooth portion 6a, and the rotor rotor 10 is rotated relative to the annular yoke piece 6-6 by the next step angle. In this manner, the two exciting coils 3 are alternately energized a desired number of times, and the direction of the current flowing through the exciting coil 3 is reversed each time the energization is performed, whereby the rotor 10 can be rotated by a desired step angle.

[0004]

However, in the above-described stepping motor, the annular yoke piece 6 is easily housed inside the cup-shaped frame yoke body 2 during assembly. Are slightly smaller than the inner dimensions of the cup-shaped frame yoke body 2 so that a slight gap 16 is provided between the frame yoke body 2 and the annular yoke piece 6. Therefore, when the motor is driven, every time the energized state of the exciting coil 3 is switched,
Magnetic attraction or repulsion acts between the frame yoke 2 and the annular yoke piece 6 with the gap 16 interposed therebetween,
As a result, the two repeat contact and separation with each other, so that a continuous vibration sound is generated, which causes noise. At the same time, vibration noise may be generated from the vibration of the winding itself of the exciting coil 3 to further increase the noise.

On the other hand, in particular, recently, there has been an increasing demand for noise reduction in various OA devices such as printers on which a stepping motor is mounted, and accordingly, it is desired to reduce the vibration or noise of the stepping motor. I was

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a stepping motor as described above, in which vibration sound or excitation due to vibration contact between a frame yoke and an annular yoke piece is provided. It is an object of the present invention to provide a stepping motor that prevents vibration noise of a coil winding and reduces noise.

[0007]

In order to achieve the above object, a first stepping motor according to the present invention comprises:
The rotor is formed by combining a rotor rotor composed of a multi-pole magnetized permanent magnet and two annular yoke portions having a plurality of comb-shaped pole portions in the circumferential direction with an excitation coil interposed therebetween. A stepping motor including two sets of yoke units disposed coaxially with each other, and a frame yoke formed to surround the exciting coil and the annular yoke. The gap between the frame yoke and the filler is filled with a filler such as synthetic resin or rubber.

Accordingly, the gap between the annular yoke portion and the frame yoke portion is closed by the filler filled therein, and the annular yoke portion is provided inside the frame yoke portion via the filler. Be combined. Therefore, vibration between the annular yoke portion and the frame yoke portion is prevented, so that noise generated at the time of driving can be reduced.

In a second stepping motor according to the present invention, a rotor rotor composed of a multi-pole magnetized permanent magnet and two circles having a plurality of comb-shaped pole portions in a circumferential direction are provided. Two sets of yoke units are arranged coaxially with the rotor by combining the annular yoke parts with an exciting coil interposed therebetween, and mounted on the outer periphery of the comb-shaped pole part of the stator yoke part. A stepping motor including the excitation coil and a frame yoke formed so as to surround the excitation coil and the annular yoke, wherein the excitation coil is wound in a groove formed on the outer periphery of the bobbin. The space formed between the inner wall of the groove and the inner wall of the frame yoke is filled and solidified with a filler such as synthetic resin or rubber.

[0010] Thus, the exciting coil is fixed inside the frame yoke by the filler provided in the space, and the filler enters between the windings of the coil, so that the windings are mutually connected. And vibration of the windings is prevented, so that noise during driving is further reduced.

A third stepping motor according to the present invention has the features of both the first stepping motor and the second stepping motor, whereby the third stepping motor has a stator yoke portion and Since both generation of noise due to vibration contact with the frame yoke and generation of noise due to the vibration of the winding itself can be suppressed, noise during driving can be further reduced.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a stepping motor according to the present invention will be described below with reference to the accompanying drawings. The same components as those in the conventional example are denoted by the same reference numerals.

FIG. 1 is a partially exploded sectional view of a stepping motor according to a first embodiment of the present invention.
In this figure, the stepping motor is shown divided into three parts, a stator part 5, a rotor rotor 10, and a plate-shaped lid member 12, and the rotor rotor 10 is housed inside the stator part 5. Then, the upper opening of the stator portion 5 is closed by a plate-shaped lid member 12 and assembled.

The stator portion 5 is formed by combining an exciting coil 3 wound around a bobbin 4 between two annular yoke pieces 6-6 having a plurality of comb-shaped pole portions on the inner periphery. It comprises two sets of yoke units 8-8 and a cup-shaped frame yoke body 2 for accommodating these two sets of yoke units 8-8. Each of the annular yoke pieces 6 is formed by bending the comb tooth-shaped pole portion 6a at an inner periphery of an annular plate by 90 degrees, and its outer dimensions are slightly smaller than the inner dimensions of the cup-shaped frame yoke body 2. Is set. The excitation coil 3 is wound around an annular groove 4a formed on the outer periphery of a bobbin 4 made of synthetic resin.

On the other hand, the cylindrical portion of the rotor rotor 10 is multipolarly magnetized along the outer circumference, and a shaft projects from both ends of the shaft of the cylindrical portion, and a lower end portion 10a and an upper end portion 10b of the shaft are respectively formed. Bearing portions 14 provided at the bottom center of the frame yoke portion 2 and the center portion of the lid member 12, respectively.
a and 14b, and are rotatably supported by the stator unit 5.

Here, a gap formed between the annular yoke piece 6 and the cup-shaped frame yoke body 2 due to a dimensional difference between the former outer diameter and the latter inner diameter is filled with a filler 20. ing. As the filler 20, synthetic resin, rubber, or the like is used. After the annular yoke piece 6 is accommodated in the cup-shaped frame yoke body 2, the filler 20 is injected into the gap in a molten state and solidified. Is preferred.
Specific materials for the filler 20 include polyetheretherketone (PEEK) and polyetherimide (PE).
I), liquid crystal polymer (LCP), ABS resin, polyamide-6 (PA-6) [brand name: nylon-6], polyamide-66 (PA-66) [brand name: nylon-6]
6], synthetic resin materials such as polybutylene terephthalate (PBT) and epoxy resin (EP), and rubber materials such as silicone rubber (organic polysiloxane) and urethane rubber (polyurethane). In particular, as the material of the filler 20, it is preferable to select a material that melts at an appropriate temperature and solidifies at normal temperature, has an appropriate viscosity, and is easy to inject. Further, the filling portion of the filler 20 may be the entire circumference along the boundary between the frame yoke body 2 and the annular yoke piece 6, or may be local at appropriate intervals along the circumferential direction. In filling the filler 20, a dispenser having a thin nozzle having a tip shape is used, and the molten filler 20 is efficiently and appropriately filled in a desired location by rotating the stator unit 5. The filling operation can be facilitated.

In the stepping motor configured as described above, the cup-shaped frame yoke 2 and the annular yoke piece 6
Is filled and solidified with the filler 20, the gap is closed, and the annular yoke piece 6 is integrally fixed inside the frame yoke body 2. The contact between the frame yoke body 2 and the annular yoke piece 6 due to vibration during driving is prevented, and noise is reduced. In particular, if a material having sufficient elasticity is selected as the material of the filler 20, the magnetic force acting between the frame yoke body 2 and the annular yoke piece 6 can be absorbed by the filler 20, further reducing noise. The effect can be enhanced.
In addition, if a material having sufficiently high thermal conductivity is selected as the material of the filler 20, heat radiation can be improved.

FIG. 2 is an exploded view of a stepping motor according to another embodiment of the present invention. In this embodiment, the structure of the stator is different from that of the embodiment shown in FIG. That is, the stator portion of this stepping motor is 2
A pair of yoke units 8a and 8b, and each of the yoke units 8a and 8b is
and a ring-shaped yoke piece 6 formed by bending a. and a ring-shaped plate portion 11a formed by bending a comb-shaped pole portion 6a on the inner periphery. An exciting coil 3 is provided inside the dish-shaped yoke 11 and the dish-shaped yoke 11 and the dish-shaped yoke. The comb-shaped pole portions 6a of the body 11 are both engaged with each other in a non-contact state. The two yoke units 8a and 8b are assembled by joining the respective annular yoke pieces 6 back to back.

In the stepping motor having such a configuration, as in the case of the first embodiment, a gap is formed between the inner peripheral wall surface 11b of the dish-shaped yoke body 11 and the outer peripheral surface of the annular yoke piece 6. Since the gap is filled with a filler 20 made of synthetic resin or rubber, the gap is closed and the annular yoke piece 6 is integrally fixed inside the frame yoke 2 by filling and solidifying the filler. Noise at the time of driving the motor can be reduced.

FIG. 4 is an exploded view of a stator section 5 of a stepping motor according to a third embodiment of the present invention. The stator portion 5 of the stepping motor has the same configuration as that of the first embodiment, except that the filling portion in the above-described embodiment is provided on the inner peripheral surface of the cup-shaped frame yoke 2 in advance. The point is that the elastic member 22 is attached. The elastic material 22 is formed of a synthetic resin material, a rubber material, or the like. As a specific material, a material having elasticity selected from those listed as the material of the filler 20 in the first embodiment is used. Is preferred. The elastic member 22 is sandwiched between the inner peripheral surface of the frame yoke body 2 and the outer peripheral surface of the annular yoke piece 6 and is interposed in a compressed state, and functions as a filler for closing a gap between the two. doing. The elastic member 22 may be provided on the inner wall of the frame yoke body 2 by molding, bonding, or the like, or may be provided by applying or printing in a molten state. When the elastic member 22 is interposed between the frame yoke member 2 and the annular yoke member 6 in this manner, the annular yoke member 6 is elastically fixed inside the frame yoke member 2, and the frame yoke member Not only can the contact between the annular yoke 6 and the annular yoke 6 be prevented, but also the magnetic force acting between the annular yoke 6 and the frame yoke 2
2, and noise can be further reduced.

It is needless to say that this elastic body 22 can be similarly applied to a stepping motor of the type shown in FIGS. 2 and 3.

FIG. 5 shows a stator section 5 of a stepping motor according to a fourth embodiment of the present invention.
The stator portion 5 of this stepping motor has the same configuration as that of the first embodiment, except that the groove portion 4a of the bobbin 4 around which the exciting coil 3 is wound.
The filling material 24 fills the entire annular space formed by the inner wall of the cup-shaped yoke 2 and the inner wall of the cup-shaped yoke 2. The filler 24 is filled into the space in a molten state and solidified. Filler 24
Is formed from a synthetic resin material, a rubber material, or the like, and the same material as the material of the filler 20 in the first embodiment is employed. In order to fill the filling material 24, a communicating portion connecting the space portion and the outside of the stator, for example, a winding external draw-out (not shown) of the exciting coil 3 formed on the outer wall of the frame yoke body 2 or an annular yoke A notch (not shown) or the like is formed in advance on the peripheral edge of the piece 6, and the cutting is performed through this notch.

As described above, the space defined by the inner wall of the groove 4a of the bobbin 4 and the inner wall of the cup-shaped frame yoke 2 is filled with the filler 24,
The filling material 24 is filled in the gap formed between the frame yoke member 2 and the annular yoke member 6, and the annular yoke member 6 is provided inside the frame yoke member 2 as in the case of the first embodiment. Can be integrally fixed. In addition, since the filler 24 enters the gap formed between the windings of the exciting coil 3, the windings can be connected to each other, and the vibration of the windings can be prevented to prevent an increase in noise. it can. Further, since the bobbin 4 is integrally fixed inside the frame yoke 2, the noise can be further reduced.

In the stepping motor according to the fourth embodiment, as shown in FIG. 5, the filler 24 is provided between the inner wall of the groove 4a of the bobbin 4 around which the exciting coil 3 is wound and the cup. As in the case of the first embodiment, the annular yoke piece 6 and the inner peripheral wall surface of the cup-shaped frame yoke 2 are formed from the entire annular space formed by being surrounded by the inner wall of the yoke 2. Although the gaps are also filled, the filled portion of the filler 24 can sufficiently reduce the noise only by the entire annular space.

In the above-described embodiment of the present invention, an example in which the bobbin 4 around which the exciting coil 3 is wound and the annular yoke piece 6 are formed separately has been described. It may be integrated by molding.

Next, FIG. 7 shows the noise reduction effect of the stepping motor according to the first embodiment shown in FIG. 1 of the present invention and the stepping motor according to the fourth embodiment shown in FIG. The results of tests performed in comparison with the conventional stepping motor are shown in Table 1 below. The first
In the fourth embodiment, a silicone resin is used as a filler. The noise was measured in an anechoic box.

[0027]

[Table 1] As is clear from the above table, by filling the space between the annular yoke piece and the frame yoke body in the first embodiment, the noise of the stepping motor can be significantly reduced as compared with the related art. it can. Further, when the filler is filled between the exciting coil and the frame yoke in the fourth embodiment in addition to the case of the first embodiment, it is apparent that the noise reduction is further improved. It is. Further, from the comparison between the first embodiment and the fourth embodiment, it can be inferred that a significant reduction in noise is caused even when the filler is filled only between the exciting coil and the frame yoke body.

[0028]

According to the stepping motor according to the first aspect of the present invention, the gap between the annular yoke and the frame yoke is filled with a filler such as synthetic resin or rubber. The gap between the annular yoke portion and the frame yoke portion is closed by the filler filled therein, and the annular yoke portion is connected to the inside of the frame yoke portion via the filler. Therefore, vibration contact between the annular yoke portion and the frame yoke portion is prevented,
Noise generated during driving can be reduced.

Further, according to the stepping motor of the second aspect of the present invention, the exciting coil is filled in the space formed between the inner wall of the groove formed on the outer periphery of the bobbin and the inner wall of the frame yoke. The filler is fixed inside the frame yoke part, and since the filler enters between the windings of the coil, the windings are bonded to each other and the vibration of the windings is prevented. The noise during driving is further reduced.

According to a third aspect of the present invention, there are provided the features of both the first and second aspects, whereby the stepping motor according to the third aspect has an annular yoke portion. It is possible to suppress both the generation of noise due to the vibration contact between the motor and the frame yoke and the generation of noise due to the vibration of the winding itself, so that the noise during driving is further reduced.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view partially exploded and showing a stepping motor according to a first embodiment of the present invention.

FIG. 2 is an exploded perspective view of a stepping motor according to a second embodiment of the present invention.

FIG. 3 is a longitudinal sectional view after assembling a stepping motor according to a second embodiment of the present invention.

FIG. 4 is an exploded longitudinal sectional view showing a stator portion of a stepping motor according to a third embodiment of the present invention.

FIG. 5 is a longitudinal sectional view of a stepping motor according to a fourth embodiment of the present invention.

FIG. 6 is an exploded perspective view showing an example of a conventional stepping motor.

FIG. 7 is a longitudinal sectional view showing the configuration of the stepping motor of FIG. 6 after assembly.

[Explanation of symbols]

2 cup-shaped frame yoke 3 excitation coil 4 bobbin 4a groove 5 stator 6 annular yoke piece 6a comb-shaped pole 8, 8a,
8b Yoke unit 10 Rotor rotor 11 Plate-shaped yoke 11a Annular yoke 11b Frame yoke 12 Cover member 14a, 1
4b Bearing part 16 Gap part 20, 2
2, 24 filler

(72) Inventor Yoshikazu Okuma 5-36-11 Shimbashi, Minato-ku, Tokyo Inside Fuji Electric Chemical Co., Ltd.

Claims (5)

[Claims] 1. A rotor rotor (10) comprising a multi-pole magnetized permanent magnet, and a plurality of comb-shaped pole portions (6) in a circumferential direction.
two annular yokes (6, 6, 11a) having a)
And two sets of yoke units (8, 8, 8a, 8b) arranged coaxially with the rotor (10) by interposing the excitation coil (3) therebetween and the excitation coil (3). 3) and a frame yoke section (2, 11b) formed so as to surround the annular yoke section (6, 6), wherein the annular yoke section (6, 6) and the frame are provided. Fillers (20, 2) such as synthetic resin and rubber are provided in gaps between the yoke portions (2, 11b).
2) A stepping motor characterized by being filled with: 2. A rotor rotor (10) comprising a multi-pole magnetized permanent magnet, and a plurality of comb-shaped pole portions (6) in a circumferential direction.
two annular yokes (6, 6, 11a) having a)
And two sets of yoke units (8, 8, 8a, 8b) coaxially arranged with the rotor (10) by combining them with the exciting coil (3) interposed therebetween, and the stator yoke portion. And a frame formed so as to surround the exciting coil (3) and the annular yoke (6, 6). In the stepping motor having the yoke portions (2, 11b), the exciting coil (3) is wound around a groove (4a) formed on the outer periphery of the bobbin (4), and the inner wall of the groove (4a) is formed. And the frame yoke portion (2, 11b)
A stepping motor characterized by filling and solidifying a filler (24) such as synthetic resin or rubber into a space formed between the stepping motor and the inner wall of the stepping motor. 3. The exciting coil (3) is wound around a groove (4a) formed on the outer periphery of the bobbin (4), and an inner wall of the groove (4a) and the frame yoke (2, 11b).
2. The stepping motor according to claim 1, wherein a filler (24) such as synthetic resin or rubber is filled and solidified in a space formed between the inner wall and the inner wall of the stepping motor. 4. The comb-shaped pole portion (6) is provided on the inner periphery of the annular plate, respectively, with the two annular yoke portions (6, 6).
The frame yoke (2) is formed in a cup shape accommodating the annular yoke (6, 6), wherein the frame yoke (2) is formed by bending a). 2. The stepping motor according to claim 1. 5. One of said two annular yoke portions (6).
Is a dish-shaped yoke body (11) in which the comb-teeth-shaped pole part (6a) is bent and formed on the inner periphery of an annular plate, and the other is formed integrally with the frame yoke part (11b) on the outer periphery. The stepping motor according to any one of claims 1 to 3, wherein the stepped motor is an annular plate portion (11a) formed by bending the comb-shaped pole portion (6a) on an inner peripheral portion of the motor.