JPH07163119A - Micromotor - Google Patents

Abstract

PURPOSE:To reduce the number of components by setting the height of a coil equal to or longer than the thickness thereof in the radial direction and eliminating the magnetic eccentricity between each pole of a rotor magnet and the upper and lower pole teeth of upper and lower pole plates. CONSTITUTION:The lower opening of a tubular metal case 1 is covered with a disc bush 2 and a shaft 6 is supported rotatably through bearings 4, 5 held in the center of the cover part. The shaft 6 is integrally provided with an annular rotor magnet 16 arranged alternately with N and S poles on the outer periphery thereof. Lower pole plates 9, 10 are disposed on the upper and lower surfaces of a coil bobbin 7. Upper pole teeth 11 of the upper pole plate 9 and lower pole teeth 12 of the lower pole plate 10 are arranged alternately along the inner peripheral face of the coil bobbin 7. A single phase concentrated winding coil 8 is applied to the coil bobbin 7 in the circumferential wall of the case 1 with the ratio of the thickness in the radial direction to the height being set low. Since a rotor magnet having large radius and height can be employed, the axial torque can be increased.

Description

Detailed Description of the Invention

[0001]

The present invention relates to an OA such as a CD-ROM.
The present invention relates to a micromotor suitable for equipment, AV equipment, in-vehicle electrical equipment, and the like.

[0002]

2. Description of the Related Art As a conventional micromotor of this type,
A brushed multi-phase DC motor is common.

However, in such a DC brush motor, since the mechanical contact is formed by the brush, not only the life is short and the noise is high, but a spark is generated between the brush and the commutator when the mechanical contact is opened. It has a drawback that it is generated and causes noise. Furthermore, when a low voltage power source such as a lithium battery is used, it cannot be driven at a voltage lower than the voltage drop of the brush, and there is a problem that low voltage driving is impossible.

Therefore, there is a demand for brushless motors of this type, but it has been difficult to generate high torque with conventional brushless motors.

On the other hand, FIGS. 11 and 12 show a capacitor splitting-phase inductor motor which is a conventionally used AC brushless micromotor. This AC micromotor covers the upper first coil bobbin B around which the first coil A is wound, the lower second coil bobbin D around which the second coil C is wound, and the first coil bobbin B from above and A cylindrical upper core magnetic circuit F having a plurality of magnetic pole teeth E arranged on the inner circumference of the coil bobbin B;
A core H of a cylindrical lower magnetic circuit having a bottom and having a plurality of magnetic pole teeth G arranged to cover the coil bobbin D from below and arranged on the inner circumference of the second coil bobbin D and a first coil bobbin B interposed between the coil bobbins B. A plurality of magnetic pole teeth I arranged on the inner circumference and a plurality of magnetic pole teeth J arranged on the inner circumference of the second coil bobbin D, and an intermediate core K of two discs for dividing both magnetic circuits, and an outer circumference The rotor L includes cylindrical permanent magnets having N and S poles alternately arranged in upper and lower two stages.

The magnetic pole teeth E of the upper core F and the magnetic pole teeth I of the intermediate core K are alternately arranged, and these are opposed to the upper permanent magnets of the rotor L, and the magnetic pole teeth G of the lower core H are arranged. And magnetic pole teeth J of the intermediate core K are alternately arranged, and these are opposed to the lower permanent magnet of the rotor L, and the shaft M of the rotor L is led out from the central hole N at the bottom of the lower core H. ing.

Both the coils A and C are connected in parallel via a capacitor O, and this parallel circuit is connected to an AC power source Q via a changeover switch P in the rotating direction. Both coils A and C are provided so as to be displaced by an electrical angle of 90 degrees. Each core F, H, K also serves as a frame (case).

In such a two-phase inductor motor, when the changeover switch P is switched to one contact, one of the coils A and C directly serves as a main coil and the other one serves as an auxiliary coil via the capacitor P. AC power supply Q
And a two-phase alternating current is supplied to both coils A and C respectively, and a rotating magnetic field is generated as a vector sum of 90 ° phase difference, so that the rotor L synchronously rotates in one direction. Further, when the changeover switch P is switched to one contact, both coils A,
The roles of the main coil and the auxiliary coil of C are exchanged, and the rotor L rotates in the other direction.

[0009]

However, in the conventional AC motor described above, in order to improve the starting characteristics,
It is necessary to provide two coils A and C having different current phases, both coils A and C, coil bobbins B and D respectively winding these coils A and C, cores F, H and K also serving as yokes, etc. Must be provided, and the number of parts increases and the cost becomes high.

The cores F and H, which cover the outside of the coil bobbins B and D, also serve as a motor case and at the same time have a function of shielding against magnetic leakage to the outside. Since the magnetic flux leaks from the cores F and H easily, the magnetism leaking from the motor causes a malfunction of peripheral equipment as the electronic equipment incorporating this type of micromotor becomes smaller.

As a solution to this problem, in a conventional motor of some kind, an annular shield plate is provided at a position corresponding to a coil (magnet) on the outer peripheral surface of the motor case, but the number of parts is further increased. Not only that, the number of assembling steps is increased and the shield plate is exposed, so that there is a problem in that there is a problem of misalignment or detachment due to this contact.

The present invention has been made in view of the above problems of the prior art. The object of the present invention is to replace the conventional DC brushed micromotor with the number of parts. It is to provide an inexpensive micromotor that has few problems.

[0013]

In order to achieve the above-mentioned object, a micromotor according to the present invention comprises a cylindrical metal case having a lid, and a bush provided in the opening of the case in a lid-like shape. A shaft that is rotatably supported by bearings in the center of the lid of the case and the center of the bush, and is integrally and coaxially fixed to the outer circumference of the shaft between the bearings and has N and S poles in the circumferential direction. Rotor magnets alternately arranged, a single coiled annular coil provided on the inner circumference of the case, upper and lower magnetic pole plates respectively arranged on the upper and lower surfaces of the coil, and coils formed on both magnetic pole plates. A plurality of upper and lower magnetic pole teeth that are arranged almost alternately on the inner circumference of the rotor so as to face the outer peripheral surface of the rotor magnet, and the cylindrical height of the coil is set to be equal to or greater than the radial thickness of the coil,
In addition, each pole of the rotor magnet and each upper and lower magnetic pole tooth of the upper and lower magnetic pole plates that form the stator are configured so as not to form magnetic eccentricity with each other.

In this case, a cylindrical yoke, which is magnetically connected to both magnetic pole plates, is provided between the inner peripheral surface of the case and the outer peripheral surface of the coil, and extends vertically on the outer peripheral portions of the upper and lower magnetic pole plates. It is desirable to form such a rising piece and magnetically connect the inner peripheral surfaces of the upper and lower ends of the yoke to the compatible upper piece.

In order to achieve the above-mentioned object, another micromotor according to the present invention comprises a base, a cylindrical support member provided upright on the base, and a rotating member inside the support member via a bearing. A freely supported shaft, a cylindrical rotor with a lid fixed to this shaft, a rotor magnet fixed to the inner surface of the peripheral wall of this rotor and having alternating different poles arranged in the circumferential direction, and outside the support. A fixed and single-wound annular coil, upper and lower magnetic pole plates respectively arranged on the upper and lower surfaces of the coil, and the outer circumferences of the coils formed on the both magnetic pole plates, facing the outer circumferential surface of the rotor magnet and almost alternately. A plurality of arranged upper and lower magnetic pole teeth, and the cylindrical height of the coil is set to be equal to or greater than the thickness of the coil in the radial direction, and each pole of the rotor magnet and each upper and lower magnetic pole tooth of the upper and lower magnetic pole plates are Mutually magnetic It is characterized in that a structure that does not form a core.

Here, in both of the micromotors,
The single-phase coil may be bidirectionally excited, and the exciting current of the coil may be supplied in a state in which the energization direction is reversed without including a pause section. Particularly, at the time of start-up, the exciting current of the coil may be supplied by changing the ratio of each energization time in bidirectional energization.

[0017]

In the above-described micromotor of the present invention,
When a single-wound single-phase coil is driven, no rotating magnetic field is generated because it is a single phase, but the upper and lower magnetic pole plates respectively placed on the upper and lower surfaces of the coil are magnetized, and both rotating magnets face the outer peripheral surface of the rotor magnet. Since magnetic attraction and repulsion between the magnetic pole teeth of the magnetic pole plate and the magnetic poles of the rotor magnet occur, for example, if the sensor detects the magnetic pole and controls energization, the shaft can rotate together with the rotor magnet.

In the case of the inner rotor type, if a cylindrical yoke is arranged outside the coil, both end portions thereof are magnetically connected to both magnetic pole plates to function as a shield, and this is covered with a metallic case. Therefore, the shield against the magnetic field of the coil is perfect. Moreover, if the rising pieces formed on the outer peripheral portions of the upper and lower magnetic pole plates are magnetically connected to the inner peripheral surfaces of the upper and lower end portions of the yoke, the connection area at the connecting portion between the yoke and the magnetic pole plate is increased and the magnetic resistance is reduced. .

Here, at the time of starting, the rotor magnet and the upper and lower magnetic pole teeth are locked at a specific position of the maximum attraction force point, so that it becomes difficult to start. Therefore, in most cases, the magnetic flux distribution is made ubiquitous to avoid the dead point angle, but this is accompanied by adverse effects such as vibration during rotation. In the present invention, this problem is solved by the method described below.

That is, it is assumed that the exciting current of a bi-directionally driven single-phase coil is supplied in a state where the energization direction is reversed without including a pause interval, and the ratio of each energization time is changed at the time of startup. N / of the pole teeth that encountered the dead center in phase
By changing the S ratio, you can avoid encountering a dead point,
Smooth startup is possible.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on the illustrated embodiments. 1 to 5 show a first embodiment in which the micromotor of the present invention is applied to an inner rotor type.

In FIG. 1, a lower surface opening of a metallic case 1 having a cylindrical shape with a lid is covered with a disk-shaped bush 2 made of resin or metal such as Duracon, and a bearing holder fitted in the central portion of the bush 2. A shaft 6 is rotatably supported via bearings 4 and 5 which are held in the interior of the case 3 and in the center of the lid of the case 1.

Inside the peripheral wall of the case 1, a single-phase coil 8 that is single-wound, that is, concentratedly wound on an annular coil bobbin 7.
Are disposed, and the radial thickness-to-height ratio is reduced. Therefore, a rotor magnet having a large radius and a large height can be used, and the axial torque can be increased. An upper magnetic pole plate 9 and a lower magnetic pole plate 10 are arranged on the upper surface and the lower surface of the coil bobbin 7, respectively. The coil bobbin 7 is made of resin such as Duracon, and has a two-part configuration as shown in FIG. In addition, the upper and lower magnetic pole plates 9 and 1
0 consists of a pressed material of a silicon steel plate containing pure iron containing approximately 1 to 2% of silicon (Si).

A plurality of upper and lower magnetic pole teeth 11 and 12 located inside the coil bobbin 7 are provided on the inner peripheral portions of the upper and lower magnetic pole plates 9 and 10.
Are respectively formed by bending, and the upper magnetic pole teeth 11 of the upper magnetic pole plate 9 and the lower magnetic pole teeth 12 of the lower magnetic pole plate 10 are alternately arranged along the inner peripheral surface of the coil bobbin 7 to form a stator magnetic pole. There is.

A cylindrical yoke 13 is arranged between the inner surface of the peripheral wall of the case 1 and the outer periphery of the coil bobbin 7.
The yoke 13 is made of a pressed material of a silicon steel plate and is formed to be longer than the coil bobbin 7 in the axial direction.
Vertically outwardly rising pieces 14 and 15 formed on the outer peripheral portion of each of 10 contact the inner surfaces of the upper and lower end portions of the yoke 13 and are magnetically connected.

The shaft 6 is integrally provided with an annular rotor magnet 16 in which N poles and S poles are alternately arranged on the outer circumference. That is, the back yoke 17 is press-fitted and fixed to the inner circumference of the rotor magnet 16, and a spacer 18 made of a resin such as DURACON is filled between the back yoke 17 and the shaft 6, so that the rotor magnet 16 is attached to the shaft 6. It is configured to rotate together with.

A circuit board 19 is arranged on the bottom of the case 1, that is, on the upper surface of the bush 2. The coil 8 is connected to the terminal portion of the circuit board 19, and the magnetic field of the rotor magnet 16 is placed on the circuit board 19. A sensor 20 such as a Hall element for detecting the temperature is attached to the drive IC, and is used for rotation direction control and maximum torque generation.

A drive control circuit for the coil 8 as shown in FIG. 3, for example, is formed on the circuit board 19. That is, this drive control circuit is connected to an external DC power source 21, and supplies a DC current to the coil 8;
A plurality of semiconductor switches connected to the coil 8, for example, transistors Tr1 to Tr4, and these transistors T
It is composed of an exciting current controller 23 connected to the bases of r1 to Tr4 and on / off controlling the transistors Tr1 to Tr4 by a signal from the sensor 20 to bidirectionally drive the coil 8.

The outer peripheral portion of the lid of the case 1 should be
Screw holes 24 for attaching the motor to an electronic device or the like
Are formed.

In the micromotor having such a structure, when the coil 8 is excited in one direction, a magnetic field is generated on the outer circumference of the coil 8 in accordance with the right-handed screw law, and the upper magnetic pole plate 9 and the lower magnetic pole plate 10 are respectively caused. For example, each upper magnetic pole tooth 11 and each lower magnetic pole tooth 1 on the inner circumference of the coil bobbin 7 are magnetized to have N and S poles.
2 is magnetized to the north and south poles, respectively.

Therefore, attractive and repulsive forces act on both magnetic poles of the rotor magnet 16 facing the surfaces of the upper and lower magnetic pole teeth 11 and 12, and a rotational force is generated in the rotor magnet 16. Furthermore, when the coil 8 is excited in the other direction,
This time, the upper and lower magnetic pole plates 9 and 10 together with the upper and lower magnetic pole teeth 11 and 12
Is magnetized to the S and N poles, repulsive force and attractive force act on the rotor magnet 16, and the rotor magnet 16 further rotates. By bidirectionally driving the coil 8 in this way, the rotor magnet 16 moves in a fixed direction. It continuously rotates.

Here, the coil 8 is supplied with an alternating exciting current having a waveform as shown in FIG. This exciting current is supplied in a state in which the energizing direction is reversed without including the rest period, as indicated by the thick arrow in the figure, so that the width of the magnetic change can be wide and a high torque based on the reverse excitation can be obtained. Will be done.

At the time of start-up, the upper and lower magnetic pole teeth 11 and 12 and the magnetic poles of the rotor magnet 16 may attract each other or repel each other depending on the timing of energization, resulting in a stationary state.

Therefore, in the drive control circuit of this embodiment,
At the time of startup, as shown in FIG. 5, an original startup sequence such that the supply time of the exciting current in the positive direction is gradually decreased and the supplying time of the exciting current in the negative direction is kept constant, and the bidirectional conduction ratio of the exciting current is changed. I am trying to use. In this example, while the N / S ratio of the rotor magnet 16 is constant, the N / S ratio of each magnetic pole tooth 11 and 12 changes, thereby escaping the dead center and realizing a smooth start.

In the above-described embodiment, the yoke 13 is arranged between the coil bobbin 7 around which the coil 8 is wound and the peripheral wall of the case 1 so that it functions as a magnetic shield and doubles with the case 1. Since the shield is realized, magnetic leakage is eliminated, and the adverse effect of leakage magnetic flux inside the electronic device can be avoided. Further, since the yoke 13 is magnetically connected to the upper and lower magnetic pole plates 9 and 10 by the rising pieces 14 and 15, the magnetic resistance between them is reduced and the magnetic loss becomes very small, and the magnetic field generated by the coil 8 is reduced. Can effectively act on the rotation of the rotor.

Next, a second embodiment in which the micromotor of the present invention is applied to the inner rotor type will be described with reference to FIGS.
Will be explained. In these drawings, the same symbols as those used above indicate the same or corresponding ones.

The coil bobbin 7 is shown in this embodiment.
A plurality of upper and smaller magnetic pole teeth 25 and 26 and lower and larger magnetic pole teeth 27 and 28 located inside the coil bobbin 7 are respectively bent in the axial direction on the inner peripheral portions of the upper and lower magnetic pole plates 9 and 10 that are arranged above and below, respectively. It is formed by. The upper and lower magnetic pole teeth 25, 26 and the lower and higher magnetic pole teeth 27, 28 have different tooth widths and are alternately arranged with an appropriate minute gap.

Then, as shown in FIG. 7, each upper large magnetic pole tooth 2 is arranged so as to face the outer peripheral surface of the rotor magnet 16.
5 and each of the lower large magnetic pole teeth 27 are alternately arranged, each upper small magnetic pole tooth 26 is on the outer peripheral surface of each lower large magnetic pole tooth 27, and each lower small magnetic pole tooth 28 is each upper large magnetic pole tooth 25. It is designed to be bonded to the outer peripheral surface.

As a result, the large magnetic pole teeth 25 and 27 face the rotor magnet 16, and the small magnetic pole teeth 28 and 26 of different polarities are present on the outer peripheral side thereof, that is, on the side opposite to the rotor magnet 16. Each large magnetic pole tooth 25, 27 constitutes a so-called teeth tip of a stator core, and each large magnetic pole tooth 2
A strong magnetic field is generated in 5, 27, and the rotor magnet 16
It is possible to increase the torque of rotation of the.

Next, a third embodiment in which the micromotor of the present invention is applied to the inner rotor type will be described with reference to FIG. In FIG. 8, the same symbols as those used above indicate the same or corresponding ones.

This embodiment shows a case where the upper and lower magnetic pole plates are made of a pressed material of a silicon steel plate containing a large amount of silicon (for example, 3%). In order to prevent cracking during press molding, Is an obtuse angle.

That is, the single coil 8 is wound in a single turn on a coil bobbin 29 having a shape in which the upper and lower collars are inclined outward in the axial direction, and the upper and lower magnetic pole plates 3 are provided above and below the coil bobbin 29.
0 and 31 are arranged, and a plurality of upper and lower magnetic pole teeth 32 and 33 located inside the coil bobbin 29 are formed on the inner peripheral portions of the upper and lower magnetic pole plates 30 and 31 by bending at obtuse angles,
The upper magnetic pole teeth 32 of the upper magnetic pole plate 30 and the lower magnetic pole teeth 33 of the lower magnetic pole plate 31 are alternately arranged along the inner peripheral surface of the coil bobbin 29 to form a stator magnetic pole.

Further, the content of silicon is increased (for example, 3
%), A cylindrical yoke 34 made of a silicon steel plate is provided between the coil bobbin 29 and the peripheral wall of the case 1, and the upper and lower end portions of the yoke 34 are the rising pieces 35 on the outer peripheral portions of the upper and lower magnetic pole plates 30 and 31. 36 magnetically connected.

Therefore, in this embodiment, since the upper and lower magnetic pole plates 30 and 31 and the yoke 34 are made of a silicon steel plate having a high silicon content, the magnetic characteristics are good and the motor characteristics are good. Become.

Next, a fourth embodiment in which the micromotor of the present invention is applied to the inner rotor type will be described with reference to FIG. In FIG. 9, the same symbols as those used above indicate the same or corresponding ones.

In this embodiment, the cylindrical diameter of the coil bobbin 37 is increased, and the coils 38,
39 is wound in the same direction as a single turn, both coils 38 and 39 are connected in series, and a partition plate 40 is interposed at the axial center of the winding portion of the coil bobbin 37.

Further, a plurality of upper and lower magnetic pole teeth 43, which are located inside the coil bobbin 37 and whose tips are located in the axial center of the coil bobbin 37, are provided on the inner peripheral portions of the upper and lower magnetic pole plates 41 and 42 arranged above and below the coil bobbin 37, respectively. , 44 are formed by bending in the axial direction, and these are alternately arranged in the circumferential direction.

The cylindrical yoke 47 provided between the coil bobbin 37 and the peripheral wall of the case 1 has the upper and lower ends thereof on the outer peripheral portions of the upper and lower magnetic pole plates 41, 42, and the rising pieces 45, 46.
Is magnetically connected to.

In this embodiment, the coils 38, 39
Is excited, a magnetic field is generated on the outer circumference of each of the coils 38 and 39 in accordance with the right-handed screw law, and the upper and lower magnetic pole plates 4
1, 42 are magnetized, and the upper and lower magnetic pole teeth 43, 44 are also magnetized. The magnetic fluxes between the coils 38 and 39 cancel each other out.

At this time, since the tips of the upper and lower magnetic pole teeth 43 and 44 which generate a strong magnetic field face the central portion of the rotor magnet 16, a large torque is generated in the rotor magnet 16 and the rotational torque is increased. Moreover, in the case of this structure, the coils 38 and 39 are arranged vertically to reduce the overall winding width, and the diameter of the cylindrical portion of the coil bobbin 37 can be increased, so that the diameter of the rotor magnet 16 can be increased. It is possible to expect a significant increase in rotation torque.

Next, a fifth embodiment in which the micromotor of the present invention is applied to the outer rotor type will be described with reference to FIG.

In FIG. 10, a cylindrical support 49 is erected on a base 48 made of resin or the like, and a bearing holder 50 is fitted into the opening at the lower end of the support 49. A shaft 53 is rotatably supported via bearings 51 and 52 arranged inside the upper end of the body 49 and inside the holder 50, respectively.

A rotor 54 made of a metal case having a cylindrical shape with a lid is fixed to the shaft 53, and an N-shaped inner surface is provided on the inner surface of the peripheral wall portion of the rotor 54 via an annular yoke 55.
A rotor magnet 56 in which poles and S poles are alternately arranged is attached.

On the outer circumference of the support 49, a single-phase coil 5 wound in a single winding around the annular coil bobbin 57, that is, concentrated winding.
8 are provided, and the thickness-height ratio in the radial direction is reduced. Therefore, when the outer diameter of the rotor 54 is constant, the radial thickness of the rotor magnet 56 can be increased by the reduction of the radial thickness, which can contribute to torque increase.

An upper magnetic pole plate 59 and a lower magnetic pole plate 60 are arranged on the upper surface and the lower surface of the coil bobbin 57, respectively. The coil bobbin 57 is made of a resin such as Duracon and has a two-divided structure, and the upper and lower magnetic pole plates 59 and 60 are pressed members made of a silicon steel plate containing pure iron containing about 1 to 2% of silicon (Si). Consists of.

On the outer peripheral portions of the upper and lower magnetic pole plates 59 and 60, the rotor magnet 56 is located outside the coil bobbin 57.
A plurality of upper and lower magnetic pole teeth 61 and 62 facing each other are formed by bending, respectively.
And the lower magnetic pole teeth 62 of the lower magnetic pole plate 60 are alternately arranged along the inner peripheral surface of the coil bobbin 57 to form a stator magnetic pole.

A circuit board 63 is arranged on the upper surface of the substrate 48, the coils 58 are connected to the terminal portions of the circuit board 63, and the rotor magnets 56 are arranged on the circuit board 63.
64 such as a Hall element for detecting the magnetic field of
Is used to control the direction of rotation and generate maximum torque.

On the circuit board 64, the drive control circuit as described with reference to FIG. 3 is formed. When the coil 58 is bidirectionally driven and the coil 58 is excited, the coil 5 is formed.
A magnetic field is generated on the outer circumference of 8 according to the right-handed screw law, and the upper magnetic pole plate 59 and the lower magnetic pole plate 60 are magnetized to, for example, N and S poles, respectively, and the upper magnetic pole teeth 6 on the outer circumference of the coil bobbin 57.
1, the lower magnetic pole teeth 62 are magnetized to the N and S poles, respectively.
Therefore, attractive and repulsive forces act on both magnetic poles of the rotor magnet 56 facing the surfaces of the upper and lower magnetic pole teeth 61 and 62, and a rotational force is generated in the rotor magnet 56, that is, the rotor 54.

At the time of start-up, the upper and lower magnetic pole teeth 61 and 62 and the magnetic poles of the rotor magnet 56 may attract or repel each other depending on the energization timing, resulting in a stationary state. In addition, by gradually reducing the supply time of the exciting current in the positive direction, keeping the supplying time of the exciting current in the negative direction constant, and using a unique starting sequence such as changing the bidirectional conduction ratio of the exciting current, the rotor While the N / S ratio of the magnet 56 is constant, the N / S ratio of each magnetic pole tooth 61, 62 changes, thereby escaping the dead center and realizing a smooth start.

Although the present invention has been described with reference to the embodiment of the micromotor capable of converting the direct current into the alternating current and energizing it, and controlling the direction of rotation in such an environment, the present invention has been described. The present invention is not limited to the above, and various modifications can be made without departing from the scope of the present invention.

For example, in each of the above-mentioned embodiments, the upper and lower magnetic pole plates are formed as separate parts, but the upper and lower magnetic pole plates are connected to the lower and upper magnetic pole teeth by a connecting portion having a small width that provides a large magnetic resistance. Alternatively, they may be integrally formed, and they may be formed at once by punching with a press.

[0062]

Since the present invention is constructed as described above, it has the following effects. Since the rotor magnet can be rotated only by a single-wound, single-phase coil, the number of parts can be greatly reduced, the cost can be reduced, and the motor itself can be made smaller than the conventional one. Is.

When a cylindrical yoke is arranged on the outside of the coil and covered with a metallic case, a shield having a double structure is realized, and an excellent shielding effect can be exhibited without producing irregularities on the outer surface. Is.

If both ends of the yoke are magnetically connected to the rising pieces formed on the outer peripheral portions of the upper and lower magnetic pole plates,
The contact area at the connection between the yoke and the pole plate is increased, the magnetic resistance is reduced, and the magnetic efficiency is increased.

Further, if the exciting current of the bi-directionally driven single-phase coil is supplied in a state where the energizing direction is reversed without including the pause section, even if the single coil is used, the high current based on the reverse excitation is generated. Torque is obtained.

By changing the ratio of the energization times of the coils that are bidirectionally driven at the time of startup, even if the dead point is encountered at one phase, the energization will be made at another phase the next time. Encounters can be avoided and smooth startup is possible.

[Brief description of drawings]

FIG. 1 is a sectional view showing a first embodiment of a micromotor according to the present invention.

FIG. 2 is an exploded perspective view of a coil bobbin, upper and lower magnetic pole plates, and a yoke of FIG.

FIG. 3 is a connection diagram showing a coil drive control circuit of the first embodiment.

FIG. 4 is a waveform diagram of an exciting current when the drive control circuit of FIG. 3 rotates at a constant speed.

5 is a waveform diagram of an exciting current at the time of starting by the drive control circuit of FIG.

FIG. 6 is a sectional view showing a second embodiment of the micromotor according to the present invention.

7 is a cutaway plan view showing the rotor magnet and the upper and lower magnetic pole teeth of FIG.

FIG. 8 is a sectional view showing a third embodiment of the micromotor according to the present invention.

FIG. 9 is a sectional view showing a fourth embodiment of the micromotor according to the present invention.

FIG. 10 is a sectional view showing a fifth embodiment of the micromotor according to the present invention.

FIG. 11 is a connection diagram showing a drive circuit of a conventional micromotor.

FIG. 12 is an exploded perspective view showing a conventional micromotor.

[Code number]

 1 Case 2 Bushing 4, 5, 51, 52 Bearing 6, 53 Shaft 8, 38, 39, 58 Coil 9, 30, 41, 59 Upper magnetic pole plate 10, 31, 42, 60 Lower magnetic pole plate 11, 32, 43, 61 upper magnetic pole tooth 12,33,44,62 lower magnetic pole tooth 13,34,47 yoke 14,15,35,36,45,46 rising piece 16,56 rotor magnet 25,26 upper large, small magnetic pole tooth 27, 28 lower large and small magnetic pole teeth 48 base 49 support 54 rotor

Claims (5)

[Claims] 1. A cylindrical metal case having a lid, a bush provided in a lid-like shape at an opening of the case, and a bearing at the center of the lid of the case and the center of the bush, respectively. Provided on the inner circumference of the case, a shaft rotatably supported by the rotor magnet, a rotor magnet integrally and coaxially fixed to the outer circumference of the shaft between the two bearings, and having different poles alternately arranged in the circumferential direction. A single-wound annular coil, upper and lower magnetic pole plates respectively arranged on the upper and lower surfaces of the coil, and an inner circumference of the coil formed on each of the both magnetic pole plates so as to face the outer circumferential surface of the rotor magnet. A plurality of upper and lower magnetic pole teeth arranged alternately, the cylindrical height of the coil is set to be equal to or greater than the radial thickness of the coil, and each pole of the rotor magnet,
A micromotor characterized in that magnetic eccentricity is not formed mutually with the upper and lower magnetic pole teeth of the upper and lower magnetic pole plates constituting the stator. 2. A cylindrical yoke, which is magnetically connected to the upper and lower magnetic pole plates, is provided between the inner peripheral surface of the case and the outer peripheral surface of the coil. 2. The micromotor according to claim 1, wherein a rising piece extending vertically is formed, and the inner peripheral surfaces of the upper and lower ends of the yoke are respectively connected to the compatible upper piece to form a magnetic shunt. 3. A base, a cylindrical support erected on the base, a shaft rotatably supported inside the support via a bearing, and a cylindrical cover having a fixed shape fixed to the shaft. A rotor, a rotor magnet fixed to the inner surface of the peripheral wall of the rotor and having alternating different poles arranged in the circumferential direction, an annular coil fixed to the outside of the support and wound in a single winding, and upper and lower surfaces of the coil Upper and lower magnetic pole plates respectively arranged on the two magnetic pole plates, and a plurality of upper and lower magnetic pole teeth formed on the both magnetic pole plates and arranged substantially alternately on the outer circumference of the coil so as to face the outer peripheral surface of the rotor magnet. The cylindrical height of the coil is set to be equal to or greater than the radial thickness of the coil, and each pole of the rotor magnet,
2. The micromotor according to claim 1, wherein magnetic eccentricity is not formed between the upper and lower magnetic pole teeth of the upper and lower magnetic pole plates forming the stator. 4. The single-phase coil is bidirectionally energized, and the exciting current of the coil is supplied in a state in which the energizing direction is reversed without substantially including a pause section. Micro motor. 5. The micromotor according to claim 4, wherein the exciting current of the coil is supplied by changing the ratio of each energization time in bidirectional energization at the time of start-up, and the drive circuit is arranged in the case.