JPH09219962A - Spindle motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To narrow the space between a salient pole forming the magnetic body and a magnet and to reduce the height dimension of the magnet by providing the constitution, wherein metal is exposed at the facing surface of the salient pole of a stator core with the drive magnet. SOLUTION: Mutual magnetic action occurs between a salient pole and a magnet 9 by applying a specified drive current to a coil 2, and a motor is rotated. The insulating layer of the facing surface of the salient pole 11 with the magnet 9 is removed, and the metal surface forming a core 1 is exposed. Therefore, a gap (d) of the magnet 9 with the salient pole 11 can be made as narrow as possible. As a result, the magnetism-collecting force between the salient pole and the magnet can be enhanced, and the mutual magnetic action can be effectively operated. Therefore, the large drive force can be generated by the small magnet 9.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art FIG. 3 is a sectional view of a conventional example showing one mode of a thin motor, which is shown in Japanese Utility Model Laid-Open No. 15677/1993.

In FIG. 3, the thin motor has a housing 7 fixed to a hole 10 formed in a base plate 6,
A shaft 4 is supported by a bearing 5 fixed to the rotor 4. The shaft 4 is fixedly mounted on a rotor yoke 8 formed of a bowl-shaped container that is continuously provided on the upper end of the drawing. The rotor is configured by providing S and N poles in an annular manner so as to alternate. On the other hand, a core 1 is continuously provided on the outer peripheral surface of the housing 7, and a coil 2 is wound around the core to form a stator 3. The tip of the core 1 and each salient pole 11 are arranged to face the magnet 9 with a gap. With this configuration, when a drive current is applied to the coil 2 wound around the core 1, magnetic interaction occurs between the salient poles and the magnet 9 to rotate the thin motor.

FIG. 4 is an enlarged view showing the inside of the chain line A in FIG.

In FIG. 4, when the coil 2 is wound around the core 1 made of a magnetic material, an insulating layer 12 is formed on the surface of the core 1 in order to prevent conduction between the core 1 and the coil 2, and then the coil 2 is wound. I am turning. That is, in order to prevent an eddy current, a thin silicon steel plate having a predetermined thickness is punched out according to the size of the core, a predetermined number of layers are stacked, and then the insulating layer 12 is formed by, for example, spraying, depping or electrostatic coating. . The insulating layer 12 may be formed by a coating means other than the above. It is desirable that the insulating layer 12 formed by these means be uniformly attached to the entire surface of the core 1. Therefore, when the ordinary coating is performed, the insulating layer 12 having the same thickness as the insulating layer 12 between the core 1 and the coil 2 is formed on the tip of the core 1 and on each salient pole facing the magnet 9 by coating.

The coercive force between the salient pole 11 and the magnet 9 increases as the salient pole 11 and the magnet 9 approach each other. Therefore, by making the gap d as narrow as possible, a large driving force can be generated with the small magnet 9. On the other hand, in the state in which each salient pole is covered with the insulating layer 12, the gap between the salient pole 11 and the magnet 9 must be provided at least in consideration of the thickness of the insulating layer, and the thickness m of the insulating layer is the stator core. It is a useless space for inducing the magnetic attraction force of.

The thin motor is set to have a very small dimension in the height direction with respect to the outer diameter of the rotor depending on the object of use. Therefore, the height dimension of the magnet 9 with respect to the stator core 1 is also reduced. If the height of the magnet 9 is simply reduced, the magnetic attraction force of the core 1 becomes small and the driving force of the motor becomes insufficient. Therefore, the height of the magnet 9 remains unchanged as the above-described configuration. It cannot be less than or equal to the value.

[0008]

SUMMARY OF THE INVENTION Therefore, according to the present invention, a salient pole and a magnet that form a magnetic body by removing the insulating layer adhering to the salient pole of the core facing the magnet and exposing the metal surface are provided. It is also an object of the present invention to provide a thin motor in which the height dimension of the magnet is reduced by narrowing the gap between the two and increasing the magnetic coercive force of the salient poles of the core to effectively work the magnetic interaction with the magnet.

[0009]

SUMMARY OF THE INVENTION Therefore, claim 1 of the present invention is provided.
In a spindle motor including a stator core made of metal having salient poles around which a coil is wound via an insulating layer, and a drive magnet which is arranged to face the stator core and is rotationally driven, the protrusion of the stator core The surface of the pole facing the driving magnet is characterized by exposing a metal surface.

A spindle motor according to a second aspect of the present invention is characterized in that the surface of the salient pole of the stator core facing the drive magnet is cut or polished to expose a metal surface.

A spindle motor according to a third aspect of the present invention is characterized in that the surface of the salient pole of the stator core facing the drive magnet has a metal surface and an insulating layer section exposed on the same peripheral surface. .

A spindle motor according to a fourth aspect of the present invention is characterized in that a vaporization rust preventive agent is applied in the vicinity of a gap formed between the salient pole of the stator core and the drive magnet.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an embodiment in which the present invention is applied to a spindle motor for driving a media disk or the like, and is contrasted with the thin motor shown in FIG.

In the spindle motor, a lower portion of the spindle shaft 14 in the drawing is supported in a radial direction by a metal bearing 15 fixed to a hole 10 opened in a magnetic circuit board 16 which also serves as a frame, and is arranged on an outer peripheral portion of the metal bearing 15. A rotor case 17 composed of a bowl-shaped container having a barrel-shaped container engaged with the spindle shaft 14 by burring processing by a ball bearing 13 provided in the middle of the drawing, and a hub base 19 composed of a resin magnet provided in the rotor case. Is supported in the thrust direction. Reference numeral 18 is a chucking magnet that magnetically attracts the disk hub, and reference numeral 20 is a positioning portion that projects a plurality of, for example, three, circumferentially on the inner surface of the rotor case, and indicates the contact position between the engagement plate 21 and the ball bearing 13. The adjustment ensures the perpendicularity between the spindle shaft 14 and the hub base 19. Further, a drive magnet 9 having S and N poles alternately arranged is annularly provided on the inner wall of the outer peripheral portion of the rotor case 17 to form a rotor. On the other hand,
A core 1 on which a coil 2 is wound around a spindle shaft 14 is attached to a circuit board 16 by a mounting screw 22 so that each salient pole of the core faces the drive magnet 9 at a constant interval.

Now, a media disk (not shown) is placed on the upper surface of the hub base 19 with the tip of the spindle shaft 14 as the center, and when the chucking magnet 18 presses the media disk toward the hub base surface, the chucking magnet 18 is attracted to the hub base 19. The media disc is positioned on the hub base. By applying a predetermined drive current to the coil 2,
A magnetic interaction occurs between the salient poles and the magnet 9 to rotate the motor and read / write to a desired position on the media disk.

FIG. 2 is an enlarged view showing the inside of the chain line B in FIG. 1, which is in contrast to the conventional example shown in FIG. The same members as those in FIG. 4 are designated by the same reference numerals, and the duplicated description of the conventional example will be omitted.

In FIG. 2, the insulating layer on the surface of the salient pole 11 facing the magnet 9 is removed, and the metal surface of the core 1 is exposed. Therefore, the gap d of the magnet 9 of the salient pole 11
Can be as narrow as possible. As a result, the magnetic attraction between the salient poles and the magnet can be increased, and the magnetic interaction can be effectively exerted, so that a large driving force can be generated with the small magnet 9.

The surface of the core 1 facing the drive magnet 9 of the salient pole is subjected to a cutting process or a polishing process with the spindle shaft insertion hole 23 of the metal bearing 15 shown in FIG. Exposed. In this case, the surface of the salient pole of the core 1 facing the drive magnet 9 has a laminated shape such that the metal surface and the cross section of the insulating layer 12 are exposed on the same peripheral surface. In addition, since the outer peripheral surface of each salient pole protruding radially is accurately positioned on the circumference from the spindle shaft insertion hole 23, when the salient pole facing surface of the magnet 9 is a perfect circle, the gap d is extremely narrow. can do. Therefore, since a large driving force can be generated with the small magnet 9, the dimension of the magnet 9 in the vertical direction in the drawing can be reduced. As a result, the thickness of the spindle motor can be reduced.

Apart from the above, in the step of forming the insulating layer,
It is also possible to expose the metal surface by applying a resist for preventing the formation of the insulating layer on the surface of the salient pole of the core 1 facing the drive magnet 9 and removing the resist after forming the insulating layer. Even in this case, the gap d can be narrowed at least by the amount corresponding to the insulating layer.

The exposed metal surface of the salient pole of the core 1 facing the drive magnet 9 may be rusted during long-term use. For this reason, if desired, the rotor case 17 shown in FIG. 2 may have an inner surface having a salient pole 11 and a drive magnet 9 in the vicinity of a gap (for example, the rotor case 17).
The rusting can be prevented by sticking the vaporized rust preventive agent 24 on the bottom surface of the above or the upper part of the drive magnet 9. Since the vaporized rust preventive agent diffuses to the outside of the rotor case 14 through the gap d, the exposed metal surface is surely covered with the rust preventive film. Therefore, stable operation can be obtained in long-term use.
Various commercial products can be used as the vaporizing rust preventive agent.

Although the outer rotor type motor has been described in the above embodiment, the present invention can also be applied to the inner rotor type motor.

[0022]

As described above, the insulating layer attached to the salient pole of the core facing the magnet of the present invention is removed,
By exposing the metal surface of the core, the gap between the salient poles forming the magnetic body and the magnet can be narrowed, and the magnetic force of the core can be increased. As a result, a desired magnetic flux can be obtained even if a magnet with a small height is used, so that the motor can be made thinner. Further, since the vaporized rust preventive agent is applied in the vicinity of the gap formed between the salient pole of the stator core and the drive magnet, the exposed metal surface is surely covered with the rust preventive film, and can be used for a long time.

[Brief description of drawings]

FIG. 1 is an embodiment in which the present invention is applied to a spindle motor.

FIG. 2 is an enlarged view of a main part of the present invention, showing an area inside a chain line B in FIG.

FIG. 3 is a cross-sectional view of a conventional thin motor.

FIG. 4 is an enlarged view of a main part of a conventional thin motor.
The inside of the chain line A is shown.

[Explanation of symbols]

 1 core 2 coil 9 drive magnet 11 salient pole 12 insulating layer 13 ball bearing 14 spindle shaft 15 metal bearing 17 rotor case

Claims (4)

[Claims] 1. A spindle motor comprising: a metal stator core having salient poles around which a coil is wound via an insulating layer; and a drive magnet arranged to face the stator core and rotationally driven, wherein the salient poles of the stator core are provided. The spindle motor is characterized in that a metal surface is exposed on a surface facing the driving magnet. 2. The spindle motor according to claim 1, wherein a surface of the salient pole of the stator core facing the drive magnet is cut or polished to expose a metal surface. 3. The spindle according to claim 1, wherein a surface of the salient pole of the stator core facing the drive magnet has a metal surface and an insulating layer cross section exposed on the same circumferential surface. motor. 4. A spindle motor according to claim 1, wherein a vaporizing rust preventive agent is applied in the vicinity of a gap formed between the salient pole of the stator core and the drive magnet. .