JPH01199364A - Bearing mechanism - Google Patents

Abstract

PURPOSE:To prevent a ground performance from being lowered even at the time of a high-speed rotation by discharging a static electricity charged at a rotary body side through the extending part of a bearing and a magnetic fluid seal to have a conductive magnetic fluid to a fixed body. CONSTITUTION:The title mechanism is equipped with a bearing 18 in which a bearing case 17 is fitted in an outer ring 18a and, simultaneously, a spindle 11d is fitted in an inner ring 18b, an extending part 19 to be extend-formed in a shaft direction to the inner ring 18b of the bearing 18, and a magnetic fluid seal 20 to be arranged in causing a conductive magnetic fluid 20d to be in contact with the extending part 19 between the extending part 19 and bearing case 17. For such a reason, when the static electricity is charged to a certain disk 7 at the rotary body side, the static electricity is discharged by flowing from the disk 7 through a hub 11b and a spindle 11a of a spindle assembling body 11, the extending part 19 of the bearing 18, the conductive magnetic fluid 21d of the magnetic fluid seal 20, a pole N20a and a pole S20b to the bearing case 17 and a housing 8 as the fixed body. Thus, the ground performance can be prevented from being lowered.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a bearing mechanism that supports a rotating body on which a disk of a magnetic disk device is mounted, and particularly relates to a bearing mechanism that supports a rotating body on which a disk of a magnetic disk device is mounted, and in particular, a bearing mechanism that provides isolation between the rotating body and a fixed body to which the rotating body is attached. The present invention relates to a bearing mechanism equipped with a magnetic fluid seal.

[Conventional technology]

As this type of prior art, for example, Japanese Patent Application Laid-Open No. 61-347
There is a first technique shown in Publication No. 71.

This first conventional technology includes a bearing that rotatably supports a shaft as a rotating body on a fixed body, a magnetic fluid seal provided between the fixed body and the shaft, a thrust bearing that supports the lower end of the shaft,
A grounding mechanism having a curved spring connected between the thrust bearing and the fixed body is provided, and a magnetic fluid seal prevents oil and dust on the bearing side from entering the space on the disk side attached to the boss of the shaft. At the same time, static electricity generated on the disk is grounded to the fixed body via the shaft, the ground Il oval thrust bearing, and the curved spring.

Further, as another conventional technique, there is a technique shown in FIG. In other words, this conventional technology is used in a magnetic disk device with a large number of disks in order to increase the storage capacity while increasing the size of the device.As shown in FIG. A bearing e has a fixed shaft fixed to a fixed to the inner ring and a rotating body d equipped with a disk C is fitted to the outer ring, and an extension part extending in the axial direction to the outer ring of the bearing e and the fixed shaft. and a magnetic fluid seal (g) in contact with the extension (not shown) between the bearings e.

The space on the e side and the space on the disk C side are cut off. In the figure, h is a stator attached to a fixed shaft, 1 is a rotor attached to a rotating body d, and the rotor 1 and stator h rotate the rotating body d around the fixed axis. In the first prior art, a ground II crown having a thrust bearing and a curved spring is provided in order to ground the static electricity that accumulates on the rotating body side, but the rotating body to which the disk is mounted is approximately 36cm long.
- When rotating at a high speed of Go rpm, the contact between the rotating body and the thrust bearing becomes unstable, leading to problems such as deterioration of grounding performance and generation of noise.

In addition, in the other prior art, the rotating body d is not only for high-speed rotation but also has a disk C mounted around a fixed shaft.
Since the grounding mechanism rotates, there is a problem in that the grounding mechanism of the first prior art cannot be used as is.

Therefore, in order to provide a grounding function, the magnetic fluid seal
The magnetic fluid is made of conductive material, and the disk on the rotating body d side? It is conceivable that the static electricity charged in c is discharged from the fixed shaft and base a via the rotating body d and the magnetic fluid seal g, but if this is done, the bearing e will come into contact with the magnetic fluid of the magnetic fluid seal g. Therefore, corrosion-inducing components such as ions contained in the magnetic fluid corrode the bearing e, and there is a problem that the function of the magnetic fluid seal g is impaired due to the corrosion.

In view of the problems of the prior art, it is an object of the present invention to prevent grounding performance from deteriorating even when rotating at high speed, reduce noise, and to provide a magnetic material having a conductive magnetic fluid between the bearing and the fixed body. An object of the present invention is to provide a bearing mechanism that can prevent a bearing from corroding even if a fluid seal is provided.

In the present invention, a bearing having a rotating body fitted to one of the outer ring and the inner ring and a fixed body fitted to the other, and the outer ring and the inner ring of the bearing are provided. An electrically conductive conductive material is connected between an extension part extending in the axial direction at one end into which the rotating body is fitted, and a fixed body fitted into the other of the outer ring and the inner ring and the extension part. and a magnetic fluid seal provided in contact with the magnetic fluid of the extension. Further, a conductive ceramic film is coated on a surface of the extension portion that comes into contact with the conductive magnetic fluid.

[Effect]

As described above, the bearing, the extension formed on the bearing,
It is constructed with a magnetic fluid seal that is provided between the fixed body and the extension part with a conductive magnetic fluid in contact with the extension part, so if static electricity is generated on the rotating body side, the static electricity will be transferred to the bearing. Electrical discharge is caused by flowing to the stationary body through one of the outer ring and the inner ring, into which the rotating body is fitted, and the magnetic fluid seal. Therefore, the static electricity charged on the rotation # side can be discharged, and since the magnetic fluid and the extension are in contact with each other, even if the rotating body rotates at high speed, the magnetic fluid of the magnetic fluid seal 20 and the extension of the bearing are in contact with each other. By obtaining stable contact,
This can prevent grounding performance from deteriorating. Furthermore, since the magnetic fluid is grounded through contact with the extension of the bearing, it is possible to suppress noise from increasing even when the bearing rotates at high speed.

Furthermore, if the conductive magnetic fluid and the bearing extension are in contact with each other, the extension may be corroded by corrosion-inducing components such as ions contained in the magnetic fluid. However, since the extension part is coated with a conductive ceramic film on the surface that comes into contact with the magnetic fluid, there is no fear that the extension part will corrode due to the ceramic film.

As a result, even when the rotating body rotates at high speed, it is possible to prevent the grounding performance from deteriorating, and also to suppress the increase in noise. Since the extension can be prevented from corroding, the quality can be greatly improved.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 to 5. FIG. 1 is an external perspective view showing a magnetic disk device to which the bearing mechanism of the present invention is applied, FIG. 2 is an exploded perspective view showing a head disk assembly of the magnetic disk device, and FIG. 3 is a line shown along the line ■-■ in FIG. FIGS. 4(a) and 4(b) are a sectional view and a bottom view showing an embodiment of the bearing mechanism of the present invention, and FIG. 5 is a sectional view of the bearing.

A magnetic disk device to which the bearing mechanism of the present invention is applied has a first
As shown in the figure, a head disk assembly 2 is housed in a housing 1, and a plurality of circuits equipped with a recording/reproducing circuit, a logic circuit, an interface circuit, etc. are installed to control the disk 7 and magnetic head 6 of the head disk assembly 2. Board 3
, 4.5 are accommodated.

As shown in FIGS. 2 and 3, the head disk assembly 2 includes an actuator assembly 9, a driving means 10, and a spindle assembly 11 as a rotating body attached to a housing 8 as a fixed body. ing.

The housing 8 serving as the fixed body is formed into a box shape with one side and bottom open, and the side opening is closed by a cover 12.

The actuator assembly 9 has a rotating member 9a, and an arm 9b that has one end attached to the rotating member 9a with a spacer 9c and supports the magnetic head 6 at the other end, and the upper part of the rotating member 9a is connected to the housing. A bearing box 16 is attached to the fulcrum member 13 attached to the upper wall 8a of the housing 8 via a bearing 14, and is attached to the lower part of the rotating member 9a via a bearing 15. A bearing box 16 is fixed to the bottom wall 8b of the housing 8. This causes the rotating member 9a to rotate around the axis.

The drive means 10 is attached to a position opposite to the arm 9b of the rotary member 9a of the actuator assembly 9 by a mounting member 10b, and includes a molded coil 10.
a, and a yoke 10c with a permanent magnet 10d inside which the coil 10a is pushed through, and a magnetic circuit is formed between the coil 10a and the permanent magnet 10d to rotate the rotating member 9a. By rotating the magnetic head 6, the magnetic head 6 is positioned at a desired position on the surface of the magnetic disk 7.

On the other hand, the spindle assembly 11 as a rotating body includes a spindle 11a, a hub 11b fixed to the outer periphery of the spindle 11a, a spacer llc for arranging a plurality of disks 7 at predetermined intervals on the hub 11b, and the disks 7, Spacer 1
The spindle 11a is supported by the housing 8 via the bearing mechanism A of the embodiment of the present invention.

Thus, the bearing mechanism A of the embodiment includes a bearing 18, an extension portion 19, and a magnetic fluid seal 20.

Specifically, as shown in FIGS. 3 and 4, the bearing 18.18 includes an outer ring 18a, an inner ring 18b, and balls disposed between both 18a and 18b by a cage (not shown). 18c, a bearing case 17 attached to the upper wall 8a of the housing 8 as a fixed body is fitted to the outer ring 18a,
In addition, the spindle 11a is press-fitted into the inner ring 18b.

Therefore, a fitting hole 17a for fitting the outer ring 18a of the bearing 18 is provided in the center of the bearing case 17. Note that the bearing case 17.17 is the upper wall 8 of the housing 8.
The one attached to the bottom wall 8b and the one attached to the bottom wall 8b have a slightly different shape, but since both of them have basically the same configuration, the one attached to the top wall 8a is shown in Fig. 4. Only one part is shown, and bolt insertion holes 17c are bored in the peripheral edge 17b so that the housing can be attached to the upper wall 8a and the bottom wall 8b with bolts, respectively.

On the other hand, the extension part 19.19 cooperates with the bearing case 17 to provide a magnetic fluid seal 20, which will be described later, and is provided at the inner end of the inner ring 18b of each bearing 18 inside the head disk assembly 2. It is formed to extend toward the direction and in the axial direction by an appropriate length.

The magnetic fluid seal 20.20 includes a ball N20a made of an annular plate made of a magnetic material and a conductive material, the outer periphery of which is fixed at a position inward from the fitting hole 17a of the bearing case 17, and arranged with a predetermined gap in the axial direction. , an annular magnet 20c attached between the balls N20a and 520b, having an outer diameter similar to those of them and an inner diameter larger than them, and a ball N20a.
+ pole 520b and a conductive magnetic fluid 20d provided between the extension part 19, the conductive magnetic fluid 20d being in contact with the extension part 19 and disposed between the extension part 19 and the bearing case 17; has been done. And magnet 20c
Ball N20a and ball 520b, magnetic fluid 2
By forming a closed magnetic path between the extension portion 19, the inside of the head disk assembly 2 on the disk 7 side is isolated from the outside, which is the bearing 18fl.

As the conductive magnetic fluid 20d, for example, when fine particles such as conductive and magnetic iron oxide are mixed into the ester solution and a closed magnetic path is formed by the magnet 20c, the fine particles are mixed into the ball N20a and the ball 520.
b. A surfactant is also mixed between the extensions 19 so that they float in the ester solution with a substantially uniform gap without being locally magnetically attracted.

As shown in FIG. 5, the extension portion 19 has a conductive ceramic film 19a coated on its surface that comes into contact with the conductive magnetic fluid 20d. Conductive ceramic film 19
a is the temperature range in which the magnetic disk device is used;
For example, a material that maintains conductivity in the range of -10 to several tens of degrees Celsius is mixed with the ceramic constituent material, and is not corroded by the corrosion-inducing components contained in the conductive magnetic fluid 20d. That's what I do.

In addition, each of the bearing cases 17 has, as shown in FIG.
A magnetic fluid leakage prevention cover 20e is integrally formed to cover the surface of the magnetic fluid seal 20 opposite to the bearing 18 and extends to the extension portion 19 side of the bearing 18, and prevents rotation of the inner ring 18b of the bearing 18 by driving the spindle 11a. Even if the magnetic fluid 20d of the magnetic fluid seal 20 is scattered during the operation, the magnetic fluid 20d can be prevented from leaking into the head disk assembly 2. Furthermore, the magnetic fluid leakage prevention cover 20e can be prevented from leaking into the head disk assembly 2. Magnetic fluid seal 2 on the inner circumference
In order to sometimes inject the magnetic fluid 20d when assembling No. 0, an injection notch 20f is formed.

A protective cover 27 is screwed to the bearing case 17 attached to the upper wall 8a of the housing 8 to prevent dust from entering the bearing 18.
At the inner position of 7, a clamper 28 for clamping the bearing 18 is screwed to the upper end surface of the spindle 11a, while a rotor is attached to the bearing case 17 attached to the bottom wall 8b of the housing 8 via a mounting member 22. 23 is disposed, and the spindle 11a is disposed in the outer circumferential direction of the rotor 23.
A stator 26 is disposed at the bottom of the rotor 23 via mounting members 24 and 25, and the stator 26 and rotor 23
A motor for rotating the spindle assembly 11 is configured.

As described above, the bearing mechanism of the embodiment includes the bearing 18 in which the bearing case 17 is fitted to the outer ring 18a and the spindle 11d is fitted to the inner ring 18b, and the extension part 19 formed to extend in the axial direction on the inner ring 18b of the bearing 18. Since a conductive magnetic fluid 20d is provided between the extension portion 19 and the bearing case 17 and a magnetic fluid seal 20 is disposed in contact with the extension portion 19, static electricity is not generated on the disk 7 on the rotating body side. When charged, the static electricity is transferred from the disk 7 to the spindle assembly 1.
1 hub 11b and spindle 11a, extension portion 19 of bearing 18. Electrical discharge occurs by flowing through the conductive magnetic fluid 20d of the magnetic fluid seal 20, the balls N20a, and the balls 520b to the bearing case 17 and the housing 8 as fixed bodies.

Therefore, static electricity charged on the rotating body side can be reliably discharged through the magnetic fluid seal 20, so even if the rotating body rotates at high speed, the magnetic driftwood 20d of the magnetic fluid seal 20 and the bearing 18
By stably obtaining contact with the extension part 19 of
This can prevent grounding performance from deteriorating. Moreover, magnetic fluid 2
Since the bearing 18 is grounded through contact with the bearing 18, noise can be suppressed from increasing even during high-speed rotation.

Furthermore, if the magnetic fluid 20d and the extension 19 of the bearing 18 are in contact with each other, there is a risk that the extension 19 will be corroded by components such as ions contained in the magnetic fluid 20d. However, since the extension portion 19 is coated with a conductive ceramic film on the surface that contacts the magnetic fluid 20d, the ceramic film 19a
Therefore, there is no risk that the extension portion 19 will corrode.

Additionally, the ferrofluidic seal 20 and the extension 19 of the bearing 18
Since both parts can be grounded using the grounding function, both parts have a grounding function.Compared to the first conventional technology, a grounding mechanism is not required, and the magnetic disk drive can not only be made thinner, but also have a correspondingly smaller number of parts. The number of assembly steps can also be reduced by reducing the number of steps.

In addition, in the illustrated example, the component parts of the bearing mechanism A are 18.19°2
0 can be integrated into the bearing case 17, so when the bearing case 17 is removed when replacing the disk 7, the bearing mechanism A can be removed all at once as an integral part of the bearing case 17. , without destroying the magnetic fluid seal 20.

In the illustrated embodiment, the bearing case 17 as a fixed body is fitted to the outer ring 18a of the bearing 18, and the spindle 11a as a rotating body is fitted to the inner ring 18b.
The present invention is not necessarily limited to this, but can also be applied to a bearing 18 in which a rotating body is fitted to the outer ring 18a and a fixed body is fitted to the inner ring 18b, as shown in FIG. In any case, the present invention can be applied to a structure in which a fixed body is fitted to one of the outer ring 18a and the inner ring 18b, and a rotating body is fitted to the other.

〔Effect of the invention〕

As described above, according to the present invention, the static electricity charged on the rotating body side is discharged to the fixed body through the extension of the bearing and the magnetic fluid seal having a conductive magnetic fluid. Even when the magnetic fluid seal rotates at high speed, stable contact between the magnetic fluid seal and the extension of the bearing can be obtained, which prevents deterioration of grounding performance and suppresses increase in noise. There is no risk of corrosion of the extension of the bearing even if the magnetic fluid of the fluid seal comes into contact with it, resulting in the effect of greatly improving quality.

[Brief explanation of the drawing]

Figure 1 shows a magnetic disk system to which the bearing mechanism of the present invention is applied!
FIG. 2 is an exploded perspective view showing the head disk assembly of the magnetic disk drive, FIG. 3 is a sectional view of the head disk assembly taken along the line ■-■ in FIG. 2, and FIG. ) and (b) are a cross-sectional view and a bottom view showing an embodiment of the bearing mechanism of the present invention, FIG. 5 is a cross-sectional view of the bearing,
FIG. 6 is a sectional view showing an example of a conventional structure. 18... Bearing, 18a... Outer ring, 18b... Inner ring, 19... Extension part, 19''... Conductive ceramic film, 20... Magnetic fluid seal, 20a''-Ball N,
20b...Pole S, 20c...Magnet, 20
d... Conductive magnetic fluid, 8... Bearing case, 11
a...Spindle. Agent Patent Attorney Tadashi Akimoto Actual Fig. 1 Fig. 5 Fig. 18 - - Tsumugi cut 18Q - Tsumugi shaft 18b - Inner shaft 19 - Zuuronaga @P 19a - - 1 Den 4 Raw Ω Yakumi, Akuhiki E
Figure 6 o CI Q(1

Claims (1)

[Claims] 1. A bearing in which a fixed body is fitted to one of an outer ring and an inner ring and a rotating body is fitted to the other, and a shaft is fitted to one end of the outer ring and the inner ring, into which the rotating body is fitted. A magnetic fluid seal provided between an extension formed to extend in the direction, a fixed body fitted to the other of the outer ring and the inner ring, and the extension, by bringing a conductive magnetic fluid into contact with the extension. A bearing mechanism comprising: a conductive ceramic film coated on a surface of the extension portion that comes into contact with a conductive magnetic fluid.