JPH04125854A - Media driving device - Google Patents

Abstract

PURPOSE:To set a device flat and to secure a distance between bearings large by providing the bearings on the inner-side of a stator in the direction of a diameter in parallel, and making the cylindrical part of a bearing supporting part to project so as to store it on the inner-side of the stator. CONSTITUTION:A pair of the bearings 32 and 33 are provided in the bearing supporting part 40 having the cylindrical part 40a. The outer diameter of a stator fitting part 22 in a motor housing 21 set to be slightly larger than the outer diameter of the tip-side part of the cylindrical part 40a and the stator 23 is engaged with the fitting part 22. Thus, the cylindrical part 40a can be stored on the inner-side of the stator 23. Thus, the bearing 33 is arranged on the inner-side of the stator 23 and the stator 23 and the bearing 33 can be provided in parallel in the direction of the diameter. Thus, the whole device can be made flat. Since the supporting part 40 has the cylindrical part 40a projected in the direction of the housing 21 and therefore the length of the supporting part 40 can be set large and the distance between a pair of the bearings 32 and 33 can be enlarged. Consequently, a hub 31 is prevented from being supported in an overhung state, the inclination of the hub 31 is reduced and mechanical precision can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to media drives such as hard disk drives.

[Prior art] For hard disk drives, the Japanese Utility Model Publication No. 58-30312
As exemplified in the above publication, a hub to which a magnetic disk is attached has a rotating shaft in its center, and this rotating shaft is attached to a motor housing via a pair of bearings;
As exemplified in Japanese Unexamined Patent Publication No. 63-277453, the hub does not have a rotating shaft, but instead a fixed shaft is provided protruding from the motor housing, and the hub is rotatably mounted on this fixed shaft via a pair of bearings. There are types that can be installed. The latter type of hard disk drive is shown in FIG. 5 or 6.

In the drive device shown in FIG. 5, a fixed shaft 2 is attached by fitting into a hollow shaft portion 1a standing upright in the center of a motor housing 1, and a stator 3 is attached to the outer periphery of this shaft 2.

A hub 6 is rotatably supported on the fixed shaft 2 via a pair of bearings 4 and 5 arranged above and below the stator 3. The hub 6 consists of a cup-shaped hub body 6a with a rotor magnet 7 attached to its inner peripheral surface, and a hub end plate 6b that closes a lower opening of the body 6a.
The bearings 4 and 5 are provided at the center of the hub body 6a and at the center of the ceiling wall of the hub body 6a. A lead wire 8 connected to the winding of the stator 3 is drawn out through a hole 2a provided in the side surface of the fixed shaft 2 and through the inside of the fixed shaft 2 and the shaft portion 1a.

The drive device shown in FIG. 6 has a stator attached to the outer periphery of a hollow shaft portion 11a that stands integrally at the center of the motor housing 11.
At the same time, a fixed shaft 1 is attached to the shaft portion 11a.
It is installed by fitting 3 pieces. This fixed shaft 13 has a pair of bearings 14 located above the stator 12.
, 15, a hub 16 is rotatably attached. - The tube 16 has a cup shape with its lower surface open, and a rotor magnet 17 is attached to its inner peripheral surface. Further, the lead wire 18 connected to the winding of the stator 12 is drawn out through the motor housing 11 without passing through the inside of the fixed shaft 13.

[Problem to be solved by the invention] However, in the one shown in FIG. 5, bearings 4 and 5 are arranged above and below the stator 3, and these three are arranged in line in the axial direction. Therefore, there is a problem that the length of the drive device in the axial direction is large. Moreover, since the hub 6 has a hub end plate 6b, the structure of the hub 6 is complicated, and the lead wire 8 must be passed through the inside of the fixed shaft 2 and the shaft portion 1a, so that the drive There is a problem that assembly of the device is troublesome.

In the one shown in Fig. 6, bearings 14 and 15 are arranged above the stator 12, and since these three are placed side by side in the axial direction, the length of the drive device in the axial direction is large. There's a problem. Furthermore, since the pair of bearings 14 and 15 are provided close to each other, the hub 6 is supported in a cantilevered manner.

Therefore, the hub 16 tends to tilt with respect to the fixed shaft 13,
The problem is that there is a strong tendency to impair mechanical accuracy.

Furthermore, in hard disk drives, there is a need to further improve the recording density on the magnetic disks (disk-shaped media). It is theoretically known that one method for achieving this is to move the head that writes data to and reads data from the magnetic disk as close as possible to the magnetic disk. For this purpose, it is necessary that the amount of dust contained in the internal space of the shield case that houses the magnetic disk is below a certain level.

On the other hand, it is known that grease is contained inside the ball bearing that rotatably supports the hub, and when the temperature of the ball bearing increases due to its operation, dust is emitted from the ball bearing using the grease as a source. ing.

In the conventional example shown in FIGS. 5 and 6 above,
Since the ball bearing on the upper side of the figure is exposed, dust is emitted from the ball bearing into the shield case. I wanted to,
If the head is placed close to the magnetic disk, dust emitted from the ball bearings will be caught between them, causing a data crash.

The purpose of the present invention is to realize flattening without compromising mechanical precision, to be easy to assemble, to prevent dust emitted from ball bearings from leaking to the outside with a simple configuration, and to provide electrical The object of the present invention is to obtain a media drive device that can realize improved characteristics or a smaller diameter.

[Means for Solving the Problems] The present invention is applied to a media drive device in which a fixed shaft is attached to a motor housing, and a hub to which media is attached to the fixed shaft is supported at a rotating shaft (F) via a pair of bearings. be done.

In order to achieve the above object, the present invention provides a bearing support part in which a cylindrical part protruding toward the motor housing is fitted in the center part of the hub and into which the fixed shaft is inserted. The above-mentioned pair of ball bearings are installed inside the cylindrical part, and the end face side opening of the above-mentioned hub in the above-mentioned bearing support part is cooled, and a closing body is attached to the above-mentioned hub, so that the end face is close to and opposite to the end face of the cylindrical part, and the outer diameter is An annular stator mounting portion that is much larger than the outer diameter of the tip end portion of the cylindrical portion is provided in the motor housing, and the tip end portion of the cylindrical portion is accommodated and the inner peripheral surface or the tip end of the cylindrical portion is accommodated. A stator that is closely opposed to the outer peripheral surface of the side portion is attached to the stator mounting portion, and a narrow bending passage is provided between the cylindrical portion and the stator mounting portion and the stator.

Further, in order to simplify the configuration, the closure body may be formed of a cap-shaped media fixing cap that is provided to cover the end of the hub and fixes the disk-shaped media to the circumference of the hub.

[Function] According to the present invention, there is provided a stator of a mortar housing in which a pair of ball bearings are disposed within a bearing support portion having a cylindrical portion, and the outer diameter is slightly larger than the outer diameter of the tip side portion of the cylindrical portion. Since the stator is attached to the stator, ball bearings can be placed inside the stator and these can be arranged radially. Further, since the cylindrical portion of the bearing support portion protrudes toward the motor housing and is housed inside the stator, its length can be ensured to be large. Therefore, it is possible to ensure a large distance between the pair of bearings provided inside the bearing support section. Furthermore, with the support structure of the hub relative to the fixed shaft as described above, there is no need to attach a hub end plate for bearing support to the hub, and with the omission of the hub end plate, the lead wires connected to the stator windings can be It can be pulled out without passing through the inside of the fixed shaft. Further, since the opening on the end surface side of the hub in the bearing support portion is closed with the closing body, it is possible to prevent dust released from the ball bearing on the side of the closing body from leaking to the outside through this opening.

Also, the inside of the bearing support part and the stator storage part of the hub are communicated via a bent passage, or this passage is narrow and generates large dynamic pressure as the hub rotates, and is also bent. flow resistance is large. This can prevent dust from the ball bearing on the motor housing side from being released to the outside. In addition, in order to form the narrow curved passage, the stator mounting portion is placed close to and opposed to the tip of the cylindrical portion, and the inner circumferential surface of the stator is placed close to the outer circumferential surface of the cylindrical portion. There is no interposition between the stator and the cylindrical portion, and the width of the stator core of the stator can be increased or the diameter of the stator can be reduced accordingly.

In addition, when the closure body is a media fixing cap,
With this closing body, the opening on the hub end face side in the bearing support portion can be closed and the disk-shaped media can be attached, so the number of parts can be reduced and the configuration can be made simpler.

[Example] Hereinafter, a first example of the present invention will be described with reference to FIGS. 1 and 2.

21 in Figure 1 is a motor housing made of iron-based material.
An annular stator mounting portion 22 is integrally formed on the upper surface of this peripheral portion, leaving a peripheral edge portion 24 on the outside thereof and protruding upward. In this installation, the outer diameter of the portion 22 is determined by the cylindrical portion 40, which will be described later.
The tip side part of a is slightly larger than the outer diameter of 2.

The stator is attached to the outer peripheral surface of the portion 22 by press-fitting the stator 23 or the lower corner of its inner periphery. Therefore, the stator 23 is positioned in the radial direction by the stator mounting portion 22, and in the vertical direction by the peripheral edge portion 24. This stator 23 is formed from a stator core having a plurality of salient poles arranged radially, and a winding wound around each salient pole.

A flexible printed wiring board 25 is bonded to the lower surface of the motor housing 21 . The wiring pattern (not shown) provided on this board 25 includes a stator 23
A lead wire (not shown) connected to the winding is connected.

A fixed shaft 26 is attached to the motor housing 21 so as to pass through the center thereof. The fixed shaft 26 is made of the same type of iron material as the motor housing 2].

A lower portion 26a of the fixed shaft 26 protruding from the lower surface of the motor housing 21 is press-fitted into a fixing hole 29 provided in a shield case 28 of the magnetic disk drive device from the inside of the case 28 and supported. . In addition,
A boss portion 30 is integral with the motor housing 21, and its lower end abuts against the inner surface of the shield case 28 for positioning.

Reference numeral 31 in FIG. 1 denotes a hub made of the same type of ferrous material as the motor housing 21, which is rotatably attached to the upper part of the fixed shaft 26 via a pair of ball bearings 32 and 33 in a configuration shown in detail later. ing.

The hub 31 covers the stator 23 and integrally has a cylindrical media mounting portion 34 with an open bottom surface. At least one disk-shaped medium, that is, a hard disk 35, 36, is attached to the outer circumferential surface of the portion 34.
is installed.

To install these disks 35 and 36, attach one hard disk 36 to the lower end flange part 34 of the media attachment part 34.
After placing it on 4a, fit the cylindrical slide 37,
Next, place the other node disk 3 on this spacer 37.
5, attach the link-shaped disc holder 38 to the hub 31.
This is done by screwing it onto the end of the holder and tightening it.

A ring-shaped rotor magnet 39 is attached to the inner peripheral surface of the media attachment section 34. These three magnets are magnetized along the radial direction, and their inner circumferential surfaces are close to and opposed to the tip surfaces of the salient poles of the stator 23.

Next, the structure of attaching the hub 31 to the fixed shaft 26 will be explained. A bearing support part 40 having a cylindrical part 40a is provided at the center of the hub 31. The cylindrical portion 40a is
The hub 31 is integrally protruded from the inner surface of the central part toward the motor housing 21, and the tip surface of the hub 31 and the tip surface of the stator mounting portion 22 have a slight gap A between them, as shown in FIG. are placed in close opposition. The distal end portion of the cylindrical portion 40a is inserted into the stator 23, and the outer peripheral surface of the distal end portion of the cylindrical portion 40a and the inner peripheral surface of the stator 23 are slightly different from each other as shown in FIG. They are closely opposed to each other with a gap B between them.

This gap B is communicated with the gap A described above.

A small diameter portion 40b is provided at the inner central portion of the bearing support portion 40. The pair of ball bearings 32 and 33 have a small diameter portion 40.
sandwiching b and being positioned at this small diameter portion 4°b,
They are attached to the inside of the bearing support part 40 in a spaced-apart manner.

The ball bearing 33 on the motor housing 21 side projects further toward the motor housing 21 than the tip of the cylindrical portion 40a.

The outer peripheral surface of the outer race and the inner peripheral surface of the stator mounting portion 22 are closely opposed to each other with a slight gap C provided therebetween. This gap C is communicated with the gap B described above.

Furthermore, the end face of the ball bearing 33 on the motor housing 21 side is closely opposed to the upper ti21ai of the motor housing 21, and a slight gap D is provided therebetween as well. This gap D is communicated with the gap C described above.

The inside of the bearing support part 40 and the stator storage part 31a of the hub 31, that is, the circular space between the media attachment part 34 and the cylindrical part 40a, communicate with each other via a narrow curved passage. This passage is formed by the gaps A to D that communicate with each other. Moreover, the gap width of the gap AD is approximately 0.1 degrees, and the gap widths of the gaps B and C are approximately 0.2 degrees. The length E of the gap B is 2.4 mm, and the inner diameter F of the stator 23 is 9.4 mm.
2+s+*.

The outer diameter G of the tip side portion of the cylindrical portion 40a is 9.
It is.

As shown in FIG. 1, a closing body 41 is attached to the end face of the hub 31 to close the opening on the end face side of the bearing support portion 40. As shown in FIG. This closure body is made of a disk and is provided flush with the end surface.

In the magnetic disk drive device described above, a pair of ball bearings 32.
33, and the outer diameter of the stator mounting portion 22 of the motor housing 21 is connected to the cylindrical portion 4 of the bearing support portion 40.
The outer diameter of the cylindrical portion 40a is made slightly larger than the outer diameter of the tip end portion 0a, and the stator 23 is fitted into the portion 22 for attachment, so the cylindrical portion 40a can be housed inside the stator 23.

Therefore, the ball bearing 33 in the bearing support part 40 can be arranged inside the stator 23, and the stator 23 and the ball bearing 33 can be arranged side by side in the radial direction.

Therefore, unlike the ball bearings 33 disposed above or below the stator 23, the ball bearings 33 do not become an element that increases the axial length of the entire device, so the entire device can be made flat.

The bearing support portion 40 is a cylindrical portion 40a that protrudes toward the motor housing 21 and is housed inside the stator 23.
Therefore, the length of the bearing support portion 40 can be ensured to be large. Therefore, the distance L (see FIG. 2) between the pair of ball bearings 32 and 33 disposed within the bearing support portion 40 is increased.

Therefore, since the hub 3 is no longer supported in a cantilevered state, the degree of inclination of the hub 31 with respect to the fixed shaft 26 due to play between the pair of ball bearings 32 and 33 can be reduced. Therefore, the mechanical precision of the device can be ensured.

Furthermore, according to the support structure of the hub 31 with respect to the fixed shaft 26 as described above, there is no need for a hub end plate to which one ball bearing is attached due to the dual-end support, and the media attachment of the hub 31 can be carried out in the portion 34. The bottom surface can be opened. Therefore, the lead wires connected to the windings of the stator 23 are connected to the fixed shaft 26.
It can be pulled out through the lower opening of the hub 31 without passing through the inside of the hub 31. Therefore, it can be assembled easily.

Also, when operating the magnetic disk drive device with the above configuration,
A pair of ball bearings 32.3 that pivotally support the hub 31 on the fixed shaft 26
Dust is emitted from the shield case 28, but this dust is prevented from being emitted into the shield case 28 in the following manner.

Since the hub 31 is attached with a closure body 41 that closes the opening on the end face side of the hub 31 in the bearing support portion 40, dust emitted upward from the upper ball bearing 32 or the closure body 41 is attached to the hub 31.
This prevents leakage into the shield case 28.

On the other hand, there is a risk that the dust coming out of the lower ball bearing 33 may leak into the shield case 28 from the opening on the lower surface of the hub 31 through the stator housing portion 31a through the bent passage.

However, the above-mentioned curved passage exists in the outflow route.

Since this passage is formed by the gap A-D and is narrow and curved, its passage resistance is extremely large. Moreover, as the hub 31 rotates, a high amount of movement and pressure is generated within the bending passage.

Therefore, this curved passage prevents dust emitted from the ball bearing 33 from flowing into the stator housing portion 31a.

That is, as described above, it is possible to prevent dust emitted from the ball bearings 32 and 33 from leaking into the shield case 28. Therefore, this configuration of the magnetic disk device is suitable for bringing the head closer to the hard disks 35 and 36 to promote higher recording density. Furthermore, since the prevention of dust leakage is implemented using the essential parts of the media drive device as described above, there is no special need for structurally complex sealing means such as magnetic fluid seals, and the above-mentioned Since the portion constituting the bent passage is also simple to process, it can be easily implemented.

Furthermore, in the case of this embodiment, due to the dimensional difference between the gaps A-D forming the bent passage, the bent passage alternately has wide portions and narrow portions. Therefore,
At the wide gap portion (gap A), air passing through this portion is rapidly expanded to reduce its pressure and attenuate its kinetic energy, creating a labyrinth effect. Therefore, leakage of the dust can be more reliably prevented.

Furthermore, in order to form the narrow bent passage, the stator mounting section 22 is placed close to and opposed to the tip of the cylindrical section 40a, and the inner circumferential surface of the stator 23 is placed close to the outer circumferential surface of the cylindrical section 40a. The part 22 is the stator 2
3 and the cylindrical portion 40a.

Therefore, it is possible to increase the width of the stator core of the stator 23 in the inner direction of this core (toward the cylindrical portion 4 LTI a horn). Therefore, the magnetic circuit space of the stator core is increased, and as a result, the electrical characteristics can be improved.

Furthermore, if the width of the stator core is not increased as described above, the diameter of the stator 23 can be reduced by bringing the inner circumferential surface of the stator 23 closer to the outer circumferential surface of the cylindrical portion 40a. This is advantageous when trying to sub-total.

The present invention may be implemented as a second embodiment shown in FIG.

That is, in this second embodiment, a small diameter end 40c is provided at the tip of the cylindrical part 40a of the bearing support part 40, and this covers the entire outer race of the lower ball bearing 33, and the end 40c The outer circumferential surface of the stator mounting portion 22 is closely opposed to the inner circumferential surface of the stator mounting portion 22, and a gap C is provided between these surfaces. Note that the configuration other than the above points is the same as the configuration of the first embodiment, including parts not shown.

Further, the present invention has a third embodiment shown in FIG. 4, in which the closure body 41. ! :Disc presser foot 38
The mesoia fixing cap which is integrated with the closure body 5]
It may also be used as a method.

That is, the closure body 51 is formed in a camp shape with a portion that covers the end surface of the hub 31, and this is screwed onto the end of the hub 31 and is broken to the end of the hub 31. As a result, the opening on the end face side of the gnat 1 in the bearing support portion 41 is substantially closed, and the hard disk 35.3
6 is installed. Note that the configuration other than the above points is the same as the configuration of the first embodiment.

Therefore, according to the third embodiment, in addition to achieving the intended purpose of the present invention, the number of parts can be reduced and the configuration and assembly can be simplified.

[Effects of the invention] As explained above, according to the configuration of the present invention, a fixed shaft is attached to the motor housing, and a hub to which a media is attached to this fixed shaft is rotatably supported via a pair of ball bearings. In a media drive device, by arranging the stator and bearing in the radial direction, the entire device can be flattened, and the length of the bearing support part can be ensured to ensure a large distance between a pair of bearings, so mechanical Ensure accuracy,
Furthermore, there is no need to provide a hub or a hub end plate, and the lead wires connected to the stator windings can be pulled out without passing through the inside of the fixed shaft, making assembly easy. Moreover, by attaching the blocker to the hub and forming a narrow curved passage between the stator mounting section, the stator, and the cylindrical section of the bearing support section, dust emitted from the pair of ball bearings can leak outside. This can be prevented with a simple configuration.

Furthermore, since the inner circumferential surface of the stator is closely opposed to the cylindrical portion, it is possible to improve electrical characteristics or reduce the diameter.

In addition, when the closure body is a media fixing cap,
With this closing body, the hub end side opening in the bearing support portion can be closed and the disk-shaped media can be attached, so that the configuration can be made simpler.

[Brief explanation of the drawing]

1 and 2 show a first embodiment of the present invention;
The figure is a longitudinal cross-sectional view of the entire magnetic disk drive, and FIG. 2 is a partial cross-sectional view showing the area around the curved passage. FIG. 3 is a partial cross section corresponding to FIG. 2, showing a second embodiment of the present invention. FIG. 4 is a longitudinal sectional view of the entire magnetic disk drive device showing a third embodiment of the present invention. FIGS. 5 and 6 are vertical sectional views showing conventional examples of holes, respectively. 21...Motor housing, 22...Stator mounting part, 23...Stator, 26...Fixed shaft, 31
...Hub, 32.33... Ball bearing, 4o... Bearing support part, 40a... Cylindrical part, 41.51... Closure body,
A-D... Gap (bent passage). Applicant's agent Patent attorney Takehiko Suzue

Claims (1)

[Scope of Claims] 1. A media drive device in which a fixed shaft is attached to a motor housing, and a hub to which media is attached to the fixed shaft is rotatably supported via a pair of ball bearings, wherein: A bearing support portion having a cylindrical portion protruding toward the motor housing and into which the fixed shaft is inserted is provided, the pair of ball bearings are mounted inside the bearing support portion, and the hub in the bearing support portion is provided with a bearing support portion into which the fixed shaft is inserted. an annular stator attachment part having a closing body for closing the end opening on the hub, the distal end face of which is close to and opposed to the distal end face of the cylindrical part, and whose outer diameter is slightly larger than the outer diameter of the distal end part of the cylindrical part; is provided in the motor housing, and a stator that accommodates the distal end portion of the cylindrical portion and whose inner circumferential surface closely opposes the outer circumferential surface of the distal end portion of the cylindrical portion is attached to the stator mounting portion, and the cylindrical portion A media drive device characterized in that a narrow bending passage is provided between the stator mounting portion and the stator. 2. The media drive device according to claim 1, wherein the closing body is a cap-shaped media fixing cap that is provided to cover an end of the hub and fixes the disk-shaped media to the circumference of the hub. .