JPH04172951A - Motor - Google Patents

Abstract

PURPOSE:To shield leakage flux from stator and rotor and to make thin a motor by providing a magnetic shielding means for covering exposed part of a coil wound around a stator core and exposed part of a driving magnet on the disc mounting face side in a magnetic disc drive motor. CONSTITUTION:Exposed part of a coil 32 wound around a stator core 31 and exposed part on the disc mounting face 23 side of a driving ring magnet 25 arranged on the outer periphery of a rotor rotating integrally with a rotary shaft 21 are covered with an electromagnetic shielding board 50. Furthermore, outer face 50c of the magnetic shielding board 50 is stepped, with predetermined dimension, against the disc mounting face 23 formed on the rotor in the vicinity of the rotor and the stator. According to the constitution, leakage flux from the stator and the rotor can be shielded and correct positional relationship can be maintained between the disc mounting face 23 and the magnetic shielding means.

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. 4 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), and (15) is a drive pin attached to the rotating body (2), and this drive pin (15) is a screw that fixes the stator (7) and the bearing mounting member (10). It engages with a window hole (not shown) in a rotary plate fixed to the rotary plate.

(16) G: An index detection element disposed on the i-frame (13), (17) is an index detection magnet disposed on the rotor (3), and this index detection element (16) and index detection The magnet (17) generates 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). Therefore, there is a limit to how thin the electric motor can be made. 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 leakage from the stator (7) and rotor (3) occurs. Since the magnetic flux directly reaches the magnetic disk and the magnetic head, there is a risk that it will have an adverse effect on recording and reproduction. For this reason, it was necessary to shield these leakage magnetic fluxes, but if the shielding member was too large, the thickness of the motor would increase, or the inside of the disk case would be damaged due to the relationship with the disk mounting surface. There was also the risk of secondary problems such as the magnetic disk not rotating smoothly.

SUMMARY OF THE INVENTION An object of the present invention is to provide a thin electric motor that can shield magnetic flux leakage from the stator and rotor, smoothly rotate a magnetic disk, 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) and a disk mounting surface (23) formed on the rotor, the outer surface has a step of a predetermined size near the rotor and stator, and the stator core ( 3
1) and magnetic shielding means made of an electromagnetic shielding material that covers the exposed portion of the rotor drive magnet (25) on the disk mounting surface (23) side. .

[Function] In the present invention, a coil (
32) and the outer surface of the magnetic shielding means is formed on the rotor to cover the exposed portion of the ring-shaped driving magnet (25) on the disk mounting surface (23) side disposed on the outer periphery of the rotor. Since it has a step of a predetermined size near the rotor and stator with respect to the disk mounting surface (23), leakage magnetic flux from the rotor drive magnet (25) and flowing to the stator coil (32) The leakage of magnetic flux caused by current can be shielded, and this leakage magnetic flux does not directly reach the magnetic disk or magnetic head, and the disk mounting surface (
23) and the magnetic shielding means, the magnetic disk rotates at an appropriate position within the disk case without interference.

[Example] The implementation of the present invention will be explained below.

FIG. 1 is a sectional view showing an electric motor according to an 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 serves as a magnet for driving the rotor. (25) covers the exposed portion on the disk mounting surface (23) side. Also,
The outer surface (50c) of this magnetic shielding plate (50) has a step of 0.2 to 0.8 mm toward the rotor and stator with respect to the disk mounting surface (23) formed on the rotor.

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 threads 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 direction of the rotation radius of the rotor at 24 equal parts around the entire circumference. The 15 coils (32) of the stator are wound in three phases, two at a time, and are 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) The leakage of magnetic flux caused by the current flowing through the drive magnet (25) can also be shielded, and the leakage magnetic flux from the drive magnet (25) does not directly reach the magnetic disk or magnetic head, unlike in the conventional case.

Furthermore, in this embodiment, the outer surface (50c) of the magnetic shielding plate (50) is
), or the rotor and stator have a step of 0.2 to 0.81, so the magnetic disk is placed on the disk mounting surface (2
3) When installed in the disk case, the magnetic disk will not interfere within the disk case. This will be explained using FIG. 3.

FIG. 3 is a sectional view showing the flexible disk.

In the figure, (60) is a disk case made of synthetic resin, etc., (61) is a magnetic disk rotatably incorporated in the disk case (60), and (62) is a magnetic disk in the center of the magnetic disk (61). It is a fixed metal rotating plate.

When the electric motor of this embodiment is used in a disk device (not shown) and a flexible disk is installed in the disk device, the rotating plate (62) of the magnetic disk (61) has magnetic properties as shown in FIG. It is attracted to the disk mounting surface (23) of the rotating body (22). In addition, a disc case (6
0) is placed on the outer surface (50c) of the magnetic shielding plate (50). At this time, the dimensions of the lower surface of the disk case (60) and the lower surface of the rotating plate (62) are nominal values of 0 according to the JIS standard.
．． It is necessary to secure 3mm.

Therefore, in this embodiment, the outer surface (50) of the magnetic shielding plate (50) is
C) has a step of 0°2 to 0.8 mm near the rotor and stator, so that when the magnetic disk (61) is mounted on the disk mounting surface (23) of the rotating body (22),
The magnetic disk (61) is now in the proper position within the disk case (60). That is, the JIS standard is satisfied, and the magnetic disk (61) rotates within the disk case (60) without interference.

As mentioned above, the electric motor of this example has a sintered oil-impregnated bearing (
Rotating Idl (21) rotatably supported by 42)
and a ring-shaped driving magnet that rotates integrally with this rotating shaft (21) and generates a magnetic field in the rotational radial direction on its outer periphery.
(25), a stator located outside the rotor and having a plurality of coils (32) wound around a stator core (31), and a stator formed on the rotor. The outer surface (50c) has a step of 0.2 to 0.8 mm (predetermined dimension) toward the rotor and stator with respect to the disk mounting surface (23), and is wound around the stator core (31). coil (3
2) and a magnetic shielding plate (50) (magnetic shielding means) made of an electromagnetic shielding material that covers the exposed portion of the rotor drive magnet (25) on the disk mounting surface (23) side.

That is, the electric motor of this embodiment includes a coil (32) wound around a stator core (31) of a stator with a magnetic shielding plate (50) (magnetic shielding means) made of an electromagnetic shielding material, and a rotating shaft (
The disk mounting surface (
23) and the magnetic shielding plate (5).
0) The outer surface (50c) of (magnetic shielding means) has a step of 0.2 to 0.8 mm toward the rotor and stator with respect to the disk mounting surface (23) formed on the rotor.

Therefore, leakage magnetic flux from the rotor drive magnet (25) can be shielded, and the stator coil (32
) can also shield magnetic flux leakage caused by current flowing through the
Since these leakage magnetic fluxes do not directly reach the magnetic disk or magnetic head, there is no risk of adversely affecting recording and reproduction by the magnetic disk and magnetic head. In addition, because the magnetic disk rotates at an appropriate position within the disk case without interference due to the positional relationship between the disk mounting surface (23) and the magnetic shielding means, the magnetic disk rotates smoothly.
Recording and reproduction using magnetic disks and magnetic heads can be performed smoothly.

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

By the way, in the above embodiment, the level difference between the disk mounting surface (23) and the outer surface (50c) of the magnetic shielding plate (50) is 0.2 to 0.2.
Although the height difference was set at 0.8 mm, the size was regulated by giving the height difference a predetermined width in this way because of magnetic disks (61).
This also takes into account manufacturing errors of the disk case (60). However, there is naturally a limit to the level difference between the disk mounting surface (23) and the outer surface (50c) of the magnetic shielding plate (50). For example, if this step is made smaller than 0.2 mm, there is a risk that the magnetic disk (61) will interfere with the lower side of the disk case (60), and if the step is made smaller than 0.8 mm,
If it is made larger than m, the magnetic disk (61) will be located too high inside the disk case (6o), so
This is because there is a possibility that the magnetic disk (61) may interfere with the upper side of the disk case (60).

[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. a link-shaped drive disposed on the outer periphery of a rotor that rotates integrally with a coil and a rotating shaft; and a magnetic shielding means made of an electromagnetic shielding material. A simple structure in which the outer surface of the magnetic shielding means has a step of a predetermined size near the rotor and stator with respect to the disk mounting surface formed on the rotor. This makes it possible to shield magnetic flux leakage from the rotor drive magnet and magnetic flux leakage caused by current flowing through the stator coil, and these leakage fluxes do not directly reach the magnetic disk or magnetic head. There is no risk of adverse effects during recording and reproduction by the magnetic head, and the magnetic disk rotates at an appropriate position within the disk case without interference due to the positional relationship between the disk mounting surface and the magnetic shielding means. The magnetic disk rotates smoothly, and the magnetic disk and magnetic head can smoothly record and reproduce data, improving reliability and safety.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an electric motor according to an embodiment of the present 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 sectional view showing a flexible disk. FIG. 4 is a sectional view showing a conventional electric motor. In the figure, 21: Rotating shaft 22: Rotating body 23: Disk mounting surface 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 3 61 2.1 6. ○!・' Princess 2362

Claims (1)

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