JP3338513B2 - Disk drive - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a disk drive.

[0002]

2. Description of the Related Art Conventionally, as a disk drive device provided with a hydrodynamic bearing portion, there is one shown in FIG.

This disk drive has a top cover a
And a fixed shaft c fixed to the base plate b, and a hub e to which a recording disk d is mounted.
The boss portion f of the hub e is rotatably fitted to the hub e.

[0004] An annular thrust plate g is fixed to the distal end of the fixed shaft c. A thrust plate g is provided inside a concave portion h formed on the distal end side of the hub e. Covered.

A dynamic pressure generating groove is formed on each end face of the thrust plate g, and a fluid for generating a dynamic pressure such as oil is filled in the concave portion h. The hydrodynamic thrust bearings j, j to be held in position are formed.

Further, a plurality of dynamic pressure generating grooves k are formed on the outer peripheral surface of the fixed shaft c or the inner peripheral surface of the boss portion f.
The fluid for generating dynamic pressure is filled between the boss portion f and the fixed shaft c, thereby forming the dynamic pressure fluid radial bearing portions m, m for rotatably supporting the hub e.

Note that a rotor magnet p provided in an annular shape is fixed inside the hub e. A stator n is disposed on the base plate b so as to face the rotor magnet p.

[0008]

As described above, the conventional disk drive requires a thrust plate g and a thrust cover i for generating a dynamic pressure in the axial direction. Therefore, there is a problem that the axial dimension of the entire drive device is increased, the structure is complicated, and the number of parts is increased.

When the disk drive becomes smaller (for example, a disk having a diameter of 1.8 inches or less), the size of the thrust plate g and the thrust cover i occupying the disk drive becomes relatively large. As a result, there is a problem that the space for mounting the magnetic circuit components by the rotor magnet p and the stator n to be installed becomes narrow, and it becomes difficult to obtain required rotational characteristics.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a disk drive device which solves the above-mentioned conventional problems, has a simple structure, requires a small number of parts and requires little processing, and can be made thin.

[0011]

In order to achieve the above object, the tip of a fixed shaft is fixed to a top cover,
The base end of the fixed shaft is fixed to a base plate parallel to the top cover, and the cylindrical boss of a hub having a cylindrical boss is rotatably fitted to the fixed shaft so as to be rotatable. The distal end face is directly or indirectly opposed to the top cover with a minute gap to form a first hydrodynamic thrust bearing portion, and the base end face of the cylindrical boss is directly or indirectly opposed to the base plate with a minute gap. Thus, a second hydrodynamic thrust bearing portion is formed.

[0012]

The first dynamic pressure fluid thrust bearing is formed by directly or indirectly facing the top surface of the cylindrical boss to the top cover, and the base end of the cylindrical boss is directly or indirectly facing the base plate. Therefore, the second hydrodynamic thrust bearing is formed, and the top cover and the base plate are used as a part of the first and second hydrodynamic thrust bearings. The thrust cover can be omitted.

Accordingly, the axial dimension of the entire apparatus can be reduced, and the shape and configuration are simplified, and the number of parts is reduced. Further, even if the driving device is downsized, the space for the magnetic circuit can be sufficiently provided, and the characteristics are not impaired.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings showing embodiments.

FIG. 1 mainly shows a motor section of a disk drive according to the present invention.
A hub 5 having a resin-made top cover 1, a metal base plate 2 disposed in parallel with the top cover 1, a fixed shaft 3 fixed to the top cover 1 and the base plate 2 orthogonally, and a cylindrical boss 4. , A stator 6 disposed on the base plate 2, and an annular flat rotor magnet 7
And

The metal base plate 2 is formed by integrally plastic working as a box including not only the bottom portion of the disk drive device but also a side wall (not shown). Then, the inside of the driving device is closed by the top cover 1 made of resin.

Thus, the fixed shaft 3 (upper side in the figure)
The distal end is fixed to the top cover 1 with screws 8 or the like, and the base end (on the lower side in FIG.
Is fixed by welding or caulking. The cylindrical boss 4 of the hub 5 is rotatably fitted on the fixed shaft 3.

Further, a disc-shaped receiving portion 9 protruding in the outer diameter direction is formed integrally with the cylindrical boss portion 4. Thus, the hub 5 includes the cylindrical boss portion 4 and the receiving portion 9.

The recording disks 10, 10 and the spacer 11 are mounted while being held by the distal end surface 9a of the receiving portion 9 and coaxially positioned by the outer peripheral surface on the distal end side of the cylindrical boss portion 4. In the illustrated example, the recording disks 10, 10 are fixed by a clamp member 12 made of polyamide, rubber, metal or the like, but may be fixed by welding or press fitting.

The rotor magnet 7 is fixed to the base end surface 9b of the receiving portion 9 in correspondence with the stator 6, and the front end surface 6a of the stator 6 and the base end surface 7a of the rotor magnet 7 face each other with a small gap.

The stator 6 is formed of a coil wound with an air core, and coils of a required number of magnetic poles are arranged in a ring on the inner surface 13 of the base plate 2 at predetermined intervals, and are fixed by bonding or the like. .

A printed circuit board (not shown) is integrally formed on the inner surface 13 side of the base plate 2 with an insulating layer interposed therebetween, and the insulating layer is further provided on the surface thereof. This printed circuit board is electrically connected to the coils of the stator 6.

That is, the base plate 2 is a metal-based printed circuit board, and therefore has both a housing constituting a drive unit and an electric wiring board. Therefore, the required wiring work is minimized, the component configuration is simplified, the space is saved, and the driving device is made thinner. By using a magnetic steel plate for the base plate 2, the magnetic flux transmitted from the rotor magnet 7 to the stator 6 is substantially increased, and the driving characteristics of the motor are improved.

On the inner surface 14 of the top cover 1, an annular flat plate-shaped ring body 16 is fixed so as to correspond to the tip end face 15 of the cylindrical boss part 4 of the hub 5. 17
Then, the front end face 15 faces with a minute gap. Ring body 16
Is made of a wear-resistant tetrafluoroethylene-based or polyamide-based synthetic resin, or a copper-based metal. By using a resin for the top cover 1, it is possible to perform integral molding with the same material as the ring body 16, or to insert-mold the ring body 16.

Then, the distal end face 15 of the cylindrical boss portion 4 is indirectly opposed to the top cover 1 via the ring body 16, so that the first
The hydrodynamic thrust bearing portion 18 is formed, and the base end surface 19 of the cylindrical boss portion 4 is directly opposed to the base plate 2 with a small gap to form the second hydrodynamic thrust bearing portion 21.

The hub 5 is rotatably supported on the fixed shaft 3 by a pair of hydrodynamic radial bearings 22 and 22 and is controlled by a control current flowing through the printed circuit board of the base plate 2. Rotates in a predetermined direction.

When the hub 5 rotates, the dynamic pressure generated in the first and second hydrodynamic thrust bearings 18 and 21 causes the hub 5 to rotate.
Is positioned at a predetermined position in the axial direction.

However, as shown in FIG. 1 and FIG.
The dynamic pressure fluid thrust bearing portion 18 includes a fluid for generating dynamic pressure such as oil (not shown) filled between the boss portion corresponding surface 17 of the ring body 16 and the distal end surface 15 of the cylindrical boss portion 4, and a cylinder. And a plurality of dynamic pressure generating grooves 23 formed on the tip end surface 15 of the boss portion 4.

The ring body 16 is provided on the top cover 1 because a certain force acts in the axial direction when the hub 5 stops rotating or starts up, and the cylindrical boss portion 4 is formed.
This is to prevent the resin top cover 1 from being damaged even if it contacts the top cover 1 side. Therefore, the ring body is made of a wear-resistant material as described above.

The ring body 16 also functions as an adjusting spacer for positioning the hub 5 in the axial direction, and is also effective when using a hub having another cylindrical boss having different dimensions. Therefore, although not shown in the present embodiment, a similar ring body can be provided also on the side of the second hydrodynamic thrust bearing 21 described below. That is, specifically, the ring body is fixed to the inner surface 13 of the base plate 2.

Further, the second hydrodynamic thrust bearing 21
Is filled between the boss corresponding surface 20 of the inner surface 13 of the base plate 2 and the base end surface 19 of the cylindrical boss 4 (not shown).
It comprises a dynamic pressure generating fluid such as oil and a plurality of dynamic pressure generating grooves 24 formed on the base end face 19 of the cylindrical boss portion 4.

In the second hydrodynamic thrust bearing portion 21, when the rotation of the hub 5 is stopped, the base end surface of the cylindrical boss portion 4 is formed.
19 is in contact with the inner surface 13 of the base plate 2. Therefore, in order to reduce the contact loss at the time of starting rotation of the hub 5, an annular projection 40 is provided on the central portion side (the fixed shaft 3 side) of the base end surface 19. Further, the rotation of the hub 5 is stopped, and the annular protrusion is formed.
In a state where 40 is in contact with the inner surface 13 of the base plate 2, oil which is a fluid for generating dynamic pressure is held and stored in the gap 41 by capillary action.

The dynamic pressure generating grooves 23, 24, ... are preferably arranged in a spiral shape such that the oil as the dynamic pressure generating fluid flows in the inner diameter direction by the rotation of the hub 5, but is preferably a herringbone shape. Groove may be used.

The dynamic pressure generating grooves 23 may be formed on the boss-corresponding surface 17 of the ring body 16 instead of the tip end surface 15 of the cylindrical boss 4.

Similarly, the dynamic pressure generating grooves 24.
Not the base end surface 19 of the base plate 2 but the surface 20 corresponding to the boss of the base plate 2.
In this case, the surface of the boss-corresponding surface 20 of the base plate 2 (the exposed metal portion from which the insulating layer has been removed) may be formed.
A dynamic pressure generating groove is formed by etching or pressing (not shown). Particularly, in this embodiment, the base plate 2
Is a printed circuit board based on metal, so that a dynamic pressure generating groove can be easily provided by etching when forming a required printed conductive pattern.

Next, the dynamic pressure fluid radial bearing portion 22 is provided between the inner peripheral surface of the cylindrical boss portion 4 of the hub 5 and the outer peripheral surface of the fixed shaft 3 by a dynamic pressure of oil (not shown) or the like. The generating fluid and a plurality of dynamic pressure generating grooves 25 formed on the outer peripheral surface of the fixed shaft 3.
And consisting of

The dynamic pressure generating grooves 25 of the dynamic pressure fluid radial bearing portion 22 are arranged in a spiral shape such that oil as a dynamic pressure generating fluid flows inward in the axial direction by rotation of the hub 5. Is preferred.

In this manner, the hydrodynamic radial bearings 22, 22 and the first and second hydrodynamic thrust bearings 18, 21 are formed.
Becomes a pump-in, has a self-sealing function, and can obtain a good pressure balance with a simple design. Of course, the hydrodynamic radial bearings 22, 22 and the first
The second hydrodynamic thrust bearing portions 18 and 21 may be configured to have a configuration other than pump-in.

The dynamic pressure generating grooves 25 may be formed not on the outer peripheral surface of the fixed shaft 3 but on the inner peripheral surface of the cylindrical boss portion 4.

In the present embodiment, oil is used as the dynamic pressure generating fluid, and the oil is contained in the first and second dynamic pressure fluid thrust bearings 18 and 21 and the dynamic pressure radial bearings 22 and 22. Oil may leak out. For this reason, a lubricating oil is applied to each bearing corresponding portion on the inner surface 14 of the top cover 1 and the inner surface 13 of the base plate 2. In particular, in the second hydrodynamic thrust bearing portion 21, oil is stored in the gap 41 formed by the annular projection 40 of the cylindrical boss portion 4, so that oil leakage is prevented and the effect is further enhanced. . Further, although not shown, an annular wall portion may be provided in the above-mentioned grease application portion.

The embodiment shown in FIG. 1 is of an axial gap type in which the stator 6 and the rotor magnet 7 constituting the magnetic circuit face each other in the axial direction, so that there is an advantage that component processing and assembly are facilitated.

FIG. 3 shows another embodiment of a radial gap type in which the stator 6 and the rotor magnet 7 face each other in the radial direction, and an outer rotor type.

In this case, the fixed shaft 3 integrally has a flange portion 26 at the base end thereof, the flange portion 26 is fixed to the base plate 2 by caulking R, and the distal end of the fixed shaft 3 is a top cover. 1 is fixed.

The stator 6 is fixed to the outer peripheral edge of the flange portion 26. This stator 6 has a stator core 27
And a coil 28 wound around the stator core 27.

The hub 5 has a cylindrical boss portion 4 rotatably fitted on the fixed shaft 3, a disk-shaped receiving portion 29 for receiving the recording disk 10, and a peripheral wall portion 30 on the inner peripheral surface of which the rotor magnet 7 is fixed. The inner peripheral surface of the rotor magnet 7 faces the outer peripheral surface of the stator core 27 with a small gap.

The hub 5 is rotatably supported on the fixed shaft 3 by a pair of dynamic pressure fluid radial bearings 22 having the same structure as in the previous embodiment.

The base end surface 19 of the cylindrical boss 4 of the hub 5
And a boss portion corresponding surface of the flange portion 26 corresponding to the base end surface 19.
31 faces with a minute gap.

Then, the base end surface 19 of the cylindrical boss portion 4 is indirectly opposed to the base plate 2 via the flange portion 26,
The second hydrodynamic thrust bearing portion 21 is formed, and the tip end surface 15 of the cylindrical boss portion 4 is separated from the top cover 1 with a small gap.
To form a first hydrodynamic thrust bearing portion 18.

The first hydrodynamic thrust bearing portion 18 is provided between the boss portion corresponding surface 32 of the inner surface 14 of the top cover 1 and the cylindrical boss portion 4.
Fluid for generating a dynamic pressure such as oil (not shown) filled between the cylindrical boss portion 4 and a plurality of dynamic pressures (similar to FIG. 2) formed on the distal end surface 15 of the cylindrical boss portion 4. And a generating groove.

Further, the second hydrodynamic thrust bearing 21
The fluid for generating dynamic pressure such as oil (not shown) filled between the boss portion corresponding surface 31 of the flange portion 26 and the base end surface 19 of the cylindrical boss portion 4 and the base end surface 19 of the cylindrical boss portion 4 (Similar to FIG. 2).

The dynamic pressure generating groove of the first hydrodynamic thrust bearing portion 18 may be formed not on the tip end surface 15 of the cylindrical boss portion 4 but on the boss portion corresponding surface 32 of the top cover 1.

Similarly, the dynamic pressure generating groove of the second hydrodynamic thrust bearing portion 21 may be formed not on the base end surface 19 of the cylindrical boss portion 4 but on the boss portion corresponding surface 31 of the flange portion 26. If
A dynamic pressure generating groove is formed by press working simultaneously with the caulking R.

Next, FIG. 4 shows another embodiment in which the embodiment of FIG. 1 is an inner rotor type of a radial gap type.

In this case, the motor corresponding portion 33 of the base plate 2 is formed in a shallow dish shape, and the stator 6 formed by winding the coil 28 around the stator core 27 is fixed to the inner peripheral surface of the motor corresponding portion 33. .

Further, the rotor magnet 7 is fixed to the outer peripheral surface of the cylindrical boss portion 4 on the base end side of the hub 5, and the inner peripheral surface of the rotor magnet 7 faces the inner peripheral surface of the stator core 27 with a small gap.

Further, the tip surface 15 of the cylindrical boss portion 4 of the hub 5
And the boss portion corresponding surface 34 of the inner surface 14 of the top cover 1 face with a minute gap.

Then, the front end face 15 of the cylindrical boss portion 4 is directly opposed to the boss portion corresponding surface 34 of the top cover 1 to form the first dynamic pressure fluid thrust bearing portion 18 and the base portion of the cylindrical boss portion 4. The second hydrodynamic thrust bearing 21 is formed by directing the end face 19 directly to the base plate 2 with a small gap.

The first hydrodynamic thrust bearing portion 18 is formed between the boss portion corresponding surface 34 of the inner surface 14 of the top cover 1 and the cylindrical boss portion 4.
Fluid for generating a dynamic pressure such as oil (not shown) filled between the cylindrical boss portion 4 and a plurality of dynamic pressures (similar to FIG. 2) formed on the distal end surface 15 of the cylindrical boss portion 4. And a generating groove.

Further, the second hydrodynamic thrust bearing 21
Is the boss-corresponding surface of the motor-corresponding portion 33 of the base plate 2.
Fluid for generating dynamic pressure such as oil (not shown) filled between the base 20 and the base end surface 19 of the cylindrical boss portion 4 and the fluid formed on the base end surface 19 of the cylindrical boss portion 4 (similar to FIG. 2). ) A plurality of dynamic pressure generating grooves.

The dynamic pressure generating groove of the first hydrodynamic thrust bearing portion 18 may be formed not on the tip end surface 15 of the cylindrical boss portion 4 but on the boss portion corresponding surface 34 of the top cover 1.

Similarly, the dynamic pressure generating groove of the second hydrodynamic thrust bearing 21 may be formed not on the base end face 19 of the cylindrical boss 4 but on the boss corresponding surface 20 of the base plate 2. A dynamic pressure generating groove is formed by etching in the same manner as in the embodiment of FIG.

The structure other than the above is the same as that of the embodiment of FIG.

[0063]

Since the present invention is configured as described above, the following significant effects can be obtained.

The top cover 1 and the base plate 2 are
Since it is used as a part of the first and second hydrodynamic thrust bearings 18 and 21, the conventional thrust cover and thrust plate are not required, and the axial dimension of the entire device can be reduced.
The thickness can be reduced.

Moreover, the shape and configuration are simple, and the number of parts
Since the number of parts processing is small and the assembly is easy, the production cost can be reduced.

Even if the driving device is downsized, a sufficient space for mounting the magnetic circuit components can be obtained, so that the required rotation characteristics are not impaired.

[Brief description of the drawings]

FIG. 1 is a sectional front view showing an embodiment of the present invention.

FIG. 2 is a plan view of a dynamic pressure generating groove.

FIG. 3 is a sectional front view showing another embodiment.

FIG. 4 is a sectional front view showing another embodiment.

FIG. 5 is a cross-sectional front view showing a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Top cover 2 Base plate 3 Fixed shaft 4 Cylindrical boss part 5 Hub 15 Tip surface 18 First dynamic pressure fluid thrust bearing portion 19 Base end surface 21 Second dynamic pressure fluid thrust bearing portion

Claims (1)

(57) [Claims] A fixed end of a fixed shaft is fixed to a top cover, a base end of the fixed shaft is fixed to a base plate parallel to the top cover, and a cylindrical boss is provided. The cylindrical boss portion 4 of the hub 5 is rotatably fitted to the fixed shaft 3 so that the distal end surface 15 of the cylindrical boss portion 4 directly or indirectly faces the top cover 1 with a small gap. While forming the hydrodynamic thrust bearing part 18,
A disk drive device in which a second hydrodynamic thrust bearing portion 21 is formed by directly or indirectly facing the base plate 2 with a minute gap between the base end surface 19 of the cylindrical boss portion 4 and the base plate 2.