JP2958148B2 - Spindle motor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spindle motor for rotating a recording disk.

[0002]

2. Description of the Related Art A spindle motor has a structure shown in FIGS. 4 and 5, for example. The motor is a substantially circular housing 4
A shaft member 5 is integrally fixed to a substantially middle portion of the housing 4. A stator 6 is provided at an intermediate portion of the shaft member 5.
Is installed. The stator 6 has a stator core 7 and a coil 8 wound on the stator 6. A rotor magnet 17 is mounted on the inner peripheral surface of the hub member 11 rotatable with respect to the housing 4, and a recording member is loaded on the outer peripheral surface.

[0003] The hub member 11 is rotatably supported via a pair of bearing members 9. And this bearing member 9
The magnetic fluid sealing means 1 is provided outside each of them. The magnetic fluid sealing means 1 prevents grease or the like from the bearing member 9 from entering a disk chamber (a chamber for accommodating a recording disk).

[0004] Generally, when a recording disk accommodated in a substantially sealed disk chamber is driven to rotate, the recording disk is subjected to flow charging by air with the rotation. The static electricity charged on the recording disk is transferred from the hub member 11 on which the recording disk is mounted to the magnetic fluid sealing means 1.
(Ie, the magnetic fluid sealing means and the magnetic fluid) to the shaft member 5 and from the shaft member 5 to the frame of the driving device through the housing 4.

[0005]

SUMMARY OF THE INVENTION Magnetic fluid sealing means 1
As shown in FIG. 5, a magnetic fluid holding means consisting of a permanent magnet and a pair of pole pieces disposed on both sides thereof is mounted on an annular bush member 2 made of, for example, aluminum. 11 is mounted on the inner peripheral surface. Then, a conductive adhesive 13 is applied across the bush member 2 and the magnetic fluid holding means, and the bush member 2 and the magnetic fluid holding means are electrically grounded via the adhesive 13. Therefore, mounting the magnetic fluid sealing means 1 requires two kinds of adhesives, an adhesive for fixing the magnetic fluid holding means and a conductive adhesive for grounding. It had to be done twice. In addition, in these bonding steps, management of the amount of the adhesive and the bonding position requires several types of jigs and machines or a highly skilled worker, and there is a problem in securing reliability.

SUMMARY OF THE INVENTION An object of the present invention is to provide a spindle motor which can easily assemble a magnetic fluid holding means and can surely ground the hub member and the magnetic fluid holding means.

[0007]

In the spindle motor according to the present invention, the magnetic fluid sealing means includes a magnetic fluid holding means for holding a magnetic fluid and a bush member for mounting the magnetic fluid holding means on a hub member. The bush member is integrally molded with a conductive plate for electrically connecting the magnetic fluid holding means and the hub member.

[0008]

In this spindle motor, since the conductive plate is integrally molded with the bush member, it is not necessary to separately assemble the conductive plate, and the magnetic fluid sealing means can be easily assembled. Also, since the hub member and the magnetic fluid holding means are electrically grounded via the conductive plate, static electricity from the hub member is reliably grounded to the magnetic fluid holding means via the conductive plate.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a spindle motor according to the present invention will be described below with reference to FIGS.

FIG. 1 is a sectional view of an embodiment of a spindle motor according to the present invention. In FIG. 1, the illustrated spindle motor includes a circular housing 20 and a hub member 22 that is rotatable relative to the housing 20.
Is provided. A circular hole is formed substantially at the center of the housing 20, and the lower end of the shaft member 24 is fixed to the hole. Although not shown, the housing 20 is fixed to the frame of the disk drive by means such as mounting screws.

A stator 26 is mounted at the center of the shaft member 24. The stator 26 has a stator core 28 fixed to the shaft member 24 and a coil 30 wound around the stator core 28 as required. In this shaft member 24,
Further, the hub member 2 is connected via a pair of bearing members 32 and 34.
2 is rotatably supported. The hub member 22 has a cylindrical hub body 36, one end (upper end) of the hub body 36 is rotatably supported via one bearing member 32, and the other end (lower end) of the hub body 36. ) Is rotatably supported via an annular bush member 38 and the other bearing member 34.

The other end of the hub body 36 is integrally provided with a flange 40. This flange portion 40
A recording disk 44 such as a plurality of magnetic disks is mounted on the upper surface of the device via a spacer member 42, and the recording disk 44 is fixed to the hub member 22 by a clamp member 46.

An annular yoke member 48 is mounted on the inner peripheral surface of the hub body 36, and an annular rotor magnet 50 is mounted on the inner peripheral surface of the yoke member 48. The rotor magnet 50 is disposed on the outer peripheral side of the stator 26 so as to face the stator 26.

Outside the bearing members 32 and 34, a magnetic fluid sealing means 52 is provided. The magnetic fluid sealing means 52 has substantially the same configuration, and hereinafter, the magnetic fluid sealing means 52 disposed outside the one (upper) bearing member 32.
Will be described. Referring also to FIGS. 2 and 3, the illustrated magnetic fluid sealing means 52 includes an annular permanent magnet 54 and a pair of pole pieces 56 disposed on both sides of the annular magnet 54.
And 58 are provided.
The magnetic fluid holding means 60 has an annular bush member 62 mounted on the inner peripheral surface of the upper end of the hub member 22 by means such as press fitting. In the embodiment, the bush member 62 is integrally formed of a synthetic resin, and extends substantially vertically from the lower wall 64, which is mounted on a shoulder formed on the inner peripheral surface of the hub member 22. An annular peripheral wall 66 and an upper wall 68 extending radially inward from the upper end of the annular peripheral wall 66 are provided. The magnetic fluid holding means 60 is fixed between the lower wall 64 and the upper wall 68.

In the embodiment, a conductive plate 70 is further provided on the bush member 62. The three conductive plates 70 are arranged at substantially equal intervals in the circumferential direction of the bush member 62. The conductive plate 70 is a bush member 62
Base 7 extending radially between lower wall 64 and peripheral wall 66
And one end of the base 72 is connected to the magnetic fluid holding means 6.
0 to the lower pole piece 58. Base 72
A contact portion 74 extending upward in a radially outward direction is integrally provided at the other end. The conductive plate 70 can be formed from a metal material such as copper or stainless steel, and the contact portion 74 acts as a leaf spring.

The conductive plate 70 can be formed integrally with the bush member 62, and it is preferable that the magnetic fluid holding means 60 be integrally formed as in the embodiment. In connection with the conductive plate 70 being disposed in this manner, the outer peripheral surface of the peripheral wall 66 of the bush member 62 is located somewhat radially inward of the outer peripheral edge of the lower wall portion 64, and
The contact portion 74 of the conductive plate 70 is located in a space formed on the outer periphery of the sixth plate 6.

The magnetic fluid holding means 60 is connected to the hub member 2.
3, the contact portion 74 of the conductive plate 70 is somewhat elastically deformed, and its free end elastically contacts the inner peripheral surface of the hub member 22, thus easily being understood from FIG. The hub member 22 and the magnetic fluid holding means 60 (the pole piece 58) are electrically grounded. Then, after the magnetic fluid holding means 60 is attached, the pair of pole pieces 5
The magnetic fluid is filled between the shaft members 6 and 58 and the shaft member 24 as required. Therefore, static electricity from the hub member 22 is grounded to the shaft member 24 mainly through the conductive plate 70 and the pole piece 58.

Although the embodiment of the spindle motor according to the present invention has been described above, the present invention is not limited to the above-described embodiment, and various changes and modifications can be made without departing from the scope of the present invention. is there.

For example, in the illustrated embodiment, three conductive plates 70 are provided at intervals in the circumferential direction. However, if grounding can be reliably performed, only one or two conductive plates 70 may be provided. .

Further, in the embodiment, the magnetic fluid holding means is constituted by a permanent magnet and a pair of pole pieces disposed on both sides of the permanent magnet. However, the present invention is not limited to this. The present invention can also be applied to a fluid holding means (for example, composed of a permanent magnet and one pole piece).

[0021]

As described above in detail, in the spindle motor of the present invention, the conductive plate is molded integrally with the bush member, and therefore, the magnetic fluid holding means can be easily assembled. Also, the hub member and the magnetic fluid holding means are electrically grounded via the conductive plate, so that static electricity from the hub member is reliably grounded to the magnetic fluid holding means via the conductive plate.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of a spindle motor according to the present invention.

FIG. 2 is a plan view of the spindle motor shown in FIG. 1;

FIG. 3 is an enlarged sectional view taken along line AA in FIG. 2;

FIG. 4 is a sectional view showing an example of a conventional spindle motor.

FIG. 5 is a plan view of the spindle motor shown in FIG. 4;

[Explanation of symbols]

 1,52 Magnetic fluid sealing means 2,62 Bush member 4,20 Housing 5,24 Shaft member 6,26 Stator 9,32,34 Bearing member 11,22 Hub member 44 Recording disk 60 Magnetic fluid holding means 70 Conductive plate

Claims (1)

(57) [Claims] 1. A housing, a hub member rotatable relative to the housing, bearing means interposed between the housing and the hub member, and a rotor magnet mounted on the hub member. A spindle motor comprising: a stator mounted on the housing so as to face the rotor magnet; and a magnetic fluid sealing means disposed outside the bearing means.
A magnetic fluid holding means for holding the magnetic fluid; and a bush member for attaching the magnetic fluid holding means to the hub member. The bush member electrically connects the magnetic fluid holding means and the hub member. A conductive plate for connecting to the spindle motor is integrally molded.