JPH04172948A - Motor - Google Patents

Abstract

PURPOSE:To shield leakage flux from a permanent magnet, to protect a stator coil and to obtain a thin motor by covering the exposed part of a coil wound around a stator core and the exposed part of a driving ring magnet arranged on the outer periphery of a rotor with an electromagnetic shielding material. CONSTITUTION:Exposed part of a coil 32 wound around a stator core 31 is covered with an electromagnetic shielding board 50 which is also applied on an exposed part at the side of the disc mounting face 23 of a driving ring magnet 25 arranged on the outer periphery of a rotor rotating integrally with a rotary shaft 21. Consequently, leakage flux from a driving magnet 25 of the rotor can be shielded and recording/reproduction by means of a magnetic disc and a magnetic head is not adversely effected. Furthermore, since the stator coil 32 is protected and does not face directly against the magnetic disc under naked state, the coil 32 does not interfere with a magnetic disc case and the like and thereby it is not damaged.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to an electric motor, and in particular to a recording device used in a device having a magnetic head for reading and writing magnetic recording signals on a magnetic disk, which is a disc-shaped recording medium. The present invention relates to an electric motor for driving rotation of a medium.

[Prior art] As a conventional electric motor of this type, Utility Model Application No. 60-13586
The technology published in Publication No. 3 can be mentioned.

FIG. 6 is a sectional view showing a conventional electric motor.

In the figure, (1) is the rotating shaft of the electric motor, (2) is a rotating body that has a magnetic disk holding function;
) rotates integrally with the rotating shaft (1). (3) is the rotor of the electric motor, (4) is the yoke of the rotor (3), (
5) is a permanent magnet arranged on the outer periphery of the yoke (4), (
6) is the screw fixing the rotor (3) and the rotating shaft (1), (7) is the stator of the motor, and (8) is the stator (
7) is the iron core, (9) is the coil wound around the iron core (8),
(10) is a bearing mounting member, and (11) and (12) are bearings that are mounted on the bearing mounting member (11) and rotatably support the rotating shaft (1). (13) is the frame of the electric motor, (
14) is a screw fixing the stator (7) and the bearing mounting member (10), (15) is a drive bin attached to the rotating body (2), and this drive bin (15) is a magnetic disk It engages with a window hole (not shown) in a rotary plate fixed to the rotary plate.

(16) is an index detection element disposed on the frame (13), (17) is an index detection magnet disposed on the rotor (3), and this index detection element (
16) and the index detection magnet (17) generate one pulse per rotation.

The electric motor with the above configuration has a rotor (3) on the outside of the stator (7).
The permanent magnet (5) of the rotor (3) generates a magnetic field in the radial direction of rotation.

[Problems to be Solved by the Invention] The conventional outer rotor type electric motor as described above requires a certain amount of space between the rotor (3) and the stator (7). Further, a frame (13) or a bearing mounting member (10) was interposed between the stator (7) and rotor (3) and the magnetic disk and magnetic head (not shown). However, there was a limit to how thin the electric motor could be. For this reason, it has been considered to create a thin inner rotor type electric motor in which the stator (7) is located outside the rotor (3).

However, in this type of electric motor, there is no frame (13) between the stator (7) and rotor (3) and the magnetic disk and magnetic head, so there is a risk that the rotor will jump out in the direction of the magnetic disk during rotation. There was that.

Furthermore, leakage magnetic flux from the permanent magnets of the rotor directly reaches the magnetic disk and the magnetic head, which may have an adverse effect on recording and reproduction.

Furthermore, the stator coils are bare and directly facing the magnetic disk case, etc., and the magnetic flux generated by the current flowing through the stator coils leaks directly to the magnetic disks and magnetic heads. There was a risk that this would have an adverse effect and that the coil itself would be damaged.

Therefore, it is an object of the present invention to provide a thin electric motor that can prevent the rotor from flying out, shield magnetic flux leakage from the permanent magnets, protect the stator coils, and has a small thickness.

[Means for Solving the Problems] The electric motor according to the present invention has a rotatably supported rotary shaft (21), rotates integrally with the rotary shaft (21), and applies a magnetic field to the outer circumference in the direction of the rotation radius. A rotor is provided with a ring-shaped driving magnet (25) and a plurality of coils (3
2), the coil (32) wound around the stator core (31), and the exposed portion of the rotor drive magnet (25) on the disk mounting surface (23) side. and magnetic shielding means made of an electromagnetic shielding material.

[Function] In the present invention, a coil (
32), and also cover the exposed portion on the disk mounting surface (23) side of the ring-shaped driving magnet (25) disposed on the outer periphery of the rotor that rotates integrally with the rotating shaft (21). Because it is covered, leakage magnetic flux from the rotor drive magnet (25) can be shielded, and this leakage magnetic flux does not directly reach the magnetic disk or magnetic head, and the stator coil (32) is also protected and exposed. Do not directly face the magnetic disk case, etc.

[Example] The embodiments of the present invention will be described above.

<First Embodiment> FIG. 1 is a sectional view showing an electric motor according to a first embodiment of the present invention.

In the figure, (21) is a rotating shaft of an electric motor, and (22) is a rotating body having a magnetic disk holding function, and this rotating body (22) rotates integrally with the rotating shaft (21). (2
3) is a disk mounting surface formed on the rotating body (22), (
24) is a rotor yoke embedded in the rotating body (22), (
25) is a driving magnet consisting of a permanent magnet arranged on the outer periphery of the rotor yoke (24), and (26) is a rotating body (
This drive pin is attached to the drive pin (22).
6) engages with a window hole (not shown) in a rotary plate fixed to the magnetic disk. (31) is a stator core, and (32) is a coil wound around the stator core (31). This stator core (31) and coil (32) constitute a stator of the electric motor.

(40) is a frame that also serves as a circuit board, (41) is a bearing mounting member attached to the frame (40), (42) is a sintered oil-impregnated bearing that rotatably supports the rotating shaft (21), (
43) is a sliding member with a low friction coefficient interposed between the rotating body (22) and the sintered oil-impregnated bearing (42). (44) is a screw that fixes the stator core (31) to the frame (40);
(45) is a spacer interposed between the stator core (31) and the frame (40). (50) is a magnetic shielding plate made of a ferromagnetic electromagnetic shielding material such as an iron plate, which covers the exposed part of the coil (32) wound around the stator core (31) and also protects the rotor drive magnet. ) (25) covers the exposed portion on the disk mounting surface (23) side.

This magnetic shielding plate (50) has an external shape as shown in FIG. FIG. 2 is a perspective view showing a magnetic shielding plate used in the electric motor of this embodiment.

In the figure, (50a) is a mounting leg formed by bending at three places on the magnetic shielding plate (50), and (50b) is a concave shape formed to match the shape of the stator core (31) of the stator. This is a flange for the section.

This magnetic shielding plate (50) is fixed to the frame (40) together with the stator core (31) by screws (44) via mounting legs (50a).

The electric motor of this embodiment is constructed as described above, and the stator core (31) is capable of passing magnetic flux in the direction of the rotation radius of the electric motor. Iron core teeth are formed at 15 angles, and 15 coils (32) are wound around the iron core teeth. The outer circumferential surface of the core at locations corresponding to the three core teeth is concave toward the inner circumferential surface, and the inner circumferential surface is connected by the core. This concave portion allows the magnetic head to move without interfering with the stator, and the concave portion flange (50b) of the magnetic shielding plate (50) fits into this concave portion. In addition, a rotor drive magnet (25
), for example, N and S poles are magnetized in the radial direction of the rotor at 24 equal parts around the entire circumference. 15 coils of stator (
32) is wound in three phases every two pieces, and is energized 120 degrees in accordance with the rotation angle of the rotor to generate rotational torque in a fixed direction.

As described above, the electric motor of this embodiment is an inner rotor type in which the stator is located outside the rotor, and the stator is formed with a concave portion for moving the magnetic head, unlike the conventional outer rotor type. Since the gap for avoiding interference between the stator and rotor and the magnetic disk and magnetic head can be omitted, as in the case of the electric motor, the thickness of the entire electric motor can be reduced.

Furthermore, in this embodiment, the exposed portion of the coil (32) wound around the stator core (31) is covered with a magnetic shielding plate (50) made of an electromagnetic shielding material, and the magnetic shielding plate (50) is also made of an electromagnetic shielding material. The exposed portion of the rotor drive magnet (25) on the disk mounting surface (23) side is covered. Therefore, leakage magnetic flux from the rotor drive magnet (25) can be shielded, and unlike the conventional drive magnet (25), leakage flux can be shielded.
25) leakage magnetic flux from the magnetic disk does not directly reach the magnetic disk or magnetic head. In addition, the stator coil (3
2) is also protected, and does not directly face the magnetic disk case or the like in a naked state, unlike in the conventional case. Furthermore, in this embodiment, the magnetic shielding plate (50) also shields leakage of magnetic flux caused by the current flowing through the coil (32) of the stator. Moreover, this magnetic shielding plate (50) also performs the function of preventing the rotor from flying out.

As mentioned above, the electric motor of this example has a sintered oil-impregnated bearing (
a rotating shaft (21) rotatably supported by 42);
A ring-shaped driving magnet (21) rotates together with this rotating shaft (21) and generates a magnetic field in the rotational radial direction on its outer circumference.
5), a stator located outside the rotor and having a plurality of coils (32) wound around the stator core (31); The wound coil (32) and the rotor driving magnet (25)
) is provided with a magnetic shielding plate (50) (magnetic shielding means) made of an electromagnetic shielding material that covers the exposed portion on the disk mounting surface (23) side of the disc.

That is, the electric motor of this embodiment covers the exposed portion of the coil (32) wound around the stator core (31) of the stator with a magnetic shielding plate (50) (magnetic shielding means) made of an electromagnetic shielding material. , a ring-shaped driving magnet (25
) covers the exposed portion on the disk mounting surface (23) side.

Therefore, leakage magnetic flux from the rotor driving magnet (25) can be shielded, and this leakage magnetic flux does not directly reach the magnetic disk or magnetic head, which adversely affects recording and reproduction by the magnetic disk and magnetic head. There is no danger. In addition, the coil (32) of the stator is also protected and does not directly face the magnetic disk etc. in a bare state, so the coil (32) is protected.
2) There is no risk of interference and damage to the magnetic disk case, etc.

Furthermore, there is no risk that the rotor will jump out during rotation.

As a result, a thin electric motor with high reliability and safety is obtained.

<Second Embodiment> FIG. 3 is a sectional view showing an electric motor according to a second embodiment of the present invention, and FIG. 4 is an enlarged sectional view of a main part of FIG. 3. In the drawings, the same reference numerals and symbols as those in the first embodiment indicate constituent parts that are the same as or correspond to those in the first embodiment.

In the figure, (24a) is a flange extending from the rotor yoke (24) made of a ferromagnetic material such as iron. Partially covered. The remaining exposed portion is covered with a magnetic shielding plate (50) made of an electromagnetic shielding material. The rest of the structure is the same as that of the first embodiment. Also, in this embodiment, the magnetic shielding plate (
50) is a coil (32) wound around a stator core (31).
) covers the exposed parts.

In this way, the electric motor of this embodiment includes the same rotating shaft (21), rotor, and stator as in the first embodiment,
The exposed portion of the coil (32) wound around the stator core (31) is covered with a magnetic shielding plate (50), and the disk mounting surface (23) of the rotor drive magnet (25) is covered with a magnetic shielding plate (50).
The exposed part of the rotor yoke ( ) side is made of electromagnetic shielding material.
24) flange part (24a) and magnetic shielding plate (50)
covered with.

Therefore, in this embodiment as well, as in the first embodiment, leakage magnetic flux from the rotor drive magnet (25) can be shielded, and this leakage flux does not directly reach the magnetic disk or the magnetic head.

Further, the stator coil (32) is also protected so that it does not directly face the magnetic disk case or the like in a bare state. Furthermore, there is no risk that the rotor will jump out during rotation.

That is, even if the exposed portion of the rotor drive magnet (25) on the disk mounting surface (23) side is covered with the flange portion (24a) of the rotor yoke (24) and the magnetic shielding plate (50) made of electromagnetic shielding material, Since there is no risk of adverse effects on recording and reproduction by the magnetic disk and magnetic head, and there is no risk of damage to the coil (32), reliability and safety are improved.

<Third Embodiment> FIG. 5 is an enlarged sectional view of essential parts of an electric motor according to a third embodiment of the present invention. In the drawings, the same reference numerals and symbols as those in the first embodiment indicate constituent parts that are the same as or correspond to those in the first embodiment.

In the figure, (27) is an annular recess formed near the insertion part of the rotor yoke (24) of the rotating body (22), and (50c)
is an annular flange formed at the central opening of the magnetic shielding plate (50). This flange portion (50c) is inserted into the recess (27) of the rotating body (22) in a non-contact manner. The other configurations are the same as those of the first and second embodiments described above. Also in this embodiment, the magnetic shielding plate (50) covers the exposed portion of the coil (32) wound around the stator core (31).

As described above, the electric motor of this embodiment includes a rotating shaft (21), a rotor, and a stator similar to those in the first and second embodiments, and is wound around the stator core (31). The exposed portion of the coil (32) is covered with a magnetic shielding plate (50), and the exposed portion of the rotor drive magnet (25) on the disk mounting surface (23) side is covered with a magnetic shielding plate (50) made of an electromagnetic shielding material. 50) and a flange portion (50c).

Therefore, similarly to the above-mentioned first embodiment and second embodiment,
The magnetic flux leakage from the rotor drive magnet (25) can be shielded, the stator coil (32) can also be protected, and,
Since the rotor can be prevented from flying out during rotation, the electric motor is highly reliable, safe, and thin. In particular, if the exposed part of the drive magnet (25) is surrounded by the magnetic shielding plate (50) and the flange part (50c) as in this embodiment, magnetic flux is less likely to leak from the drive magnet (25). Therefore, the magnetic flux shielding effect is further improved.

[Effects of the Invention] As described above, the electric motor of the present invention includes a rotatably supported rotating shaft, a rotor that rotates integrally with the rotating shaft, and a stator located outside the rotor. The magnetic shielding means is provided with a magnetic shielding means made of an electromagnetic shielding material, and the magnetic shielding means covers the exposed part of the coil wound around the stator core of the stator, and is arranged on the outer periphery of the rotor that rotates integrally with the rotating shaft. By covering the exposed part of the ring-shaped drive magnet on the disk mounting surface side, leakage magnetic flux from the rotor drive magnet can be shielded, and this leakage flux can directly reach the magnetic disk or magnetic head. Since it does not reach the magnetic disk, there is no risk of adverse effects on recording and reproduction by the magnetic disk and magnetic head, and the stator coil is also protected and does not directly face the magnetic disk case, etc.
There is no risk of damage to the coil, improving reliability and safety.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing an electric motor according to a first embodiment of this invention, FIG. 2 is a perspective view showing a magnetic shielding plate used in the electric motor of this invention, and FIG. 3 is a second embodiment of this invention. 4 is an enlarged sectional view of the main part of FIG. 3,
FIG. 5 is an enlarged sectional view of essential parts of a motor according to a third embodiment of the present invention, and FIG. 6 is a sectional view showing a conventional motor. In the figure, 21: rotating shaft 22: rotating body 23: disk mounting surface 24: rotor yoke 25: driving magnet 31: stator core 32: coil 50: magnetic shielding plate. In the drawings, the same reference numerals and the same symbols indicate the same or equivalent parts. Agent: Patent attorney Masuo Daikichi and two others Figure 4 Figure 5

Claims (1)

[Scope of Claims] A rotating shaft rotatably supported; a rotor that rotates together with the rotating shaft and is provided with a ring-shaped driving magnet that generates a magnetic field on its outer periphery; and the rotating shaft. A stator located outside the child and having a plurality of coils wound around the stator core, and exposed portions of the coils wound around the stator core and the drive magnet of the rotor on the disk mounting surface side. 1. An electric motor comprising a magnetic shielding means made of an electromagnetic shielding material.