JPH07121978A - Magnetic disk driver - Google Patents

Abstract

PURPOSE:To obtain a magnetic disk driver which has an easy dimensional management of components and a low processing cost and in which a gap of a labyrinth structure can be reduced with a high dust preventive effect. CONSTITUTION:The magnetic disk driver comprises a shaft 2, a frame 1, a hub 7 for holding a magnetic disk, and a bearing 5 in which an inner race 51 is engaged with the shaft 2 to rotatably support the hub 7. An opposite member 12 opposed at a gap to an outer periphery of a bearing outer race 52 is provided, and the gap is provided on the way of a space communicating from an interior of the bearing 5 with an exterior to form a labyrinth. Part of the member 12 may be opposed at a suitable gap to an axial end face of the bearing 5 or a sealing member 27 of the bearing. The member may be formed of a cylindrical part formed at the hub.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic disk drive device, and more particularly to a labyrinth structure for a space from its bearing portion to the outside.

[0002]

2. Description of the Related Art For example, in a hard disk drive motor, in order to prevent oil mist and other dust generated in a bearing for rotatably supporting a hub from adhering to the hard disk held by the hub, the inside of the bearing is externally exposed. There is a labyrinth structure in the middle of the space leading to. 8 and 9 show an example of a conventional magnetic disk drive device having such a labyrinth structure.

In FIG. 8, a frame 71 has a cylindrical portion 71a at its center, a shaft 72 is press-fitted to the inner peripheral side of the cylindrical portion 71a, and a stator core is fixed to the outer peripheral side of the cylindrical portion 71a. 73 is fixed. The stator core 73 has a plurality of salient poles, and a drive coil 74 is wound around each salient pole. Inner rings of two bearings 75 and 76 are fixed to a shaft 72 protruding above the frame 71, and a hub 77 is fixed to the outer rings of the bearings 75 and 76 by press fitting.
The hub 77 is rotatably supported. The hub 77 has a cylindrical outer peripheral surface 82 and a flange portion 81 following it, and the hard disk fitted to the outer peripheral surface 82 has a flange portion 81.
The hard disk is rotated integrally with the hub 77 by being clamped by an appropriate clamper fixed to the hub 77.

The hub 77 has a peripheral wall below the flange 81, and a ring-shaped drive magnet 79 is fixed to the inner peripheral side of the peripheral wall. The inner peripheral surface of the drive magnet 79 faces the tip surfaces of the salient poles of the stator core 73 with an appropriate gap. Therefore, the hub 77 and the hard disk can be rotationally driven at a predetermined speed by switching and controlling the energization of each drive coil 74 according to the rotational position of the drive magnet 79. Another small peripheral wall 86 is integrally formed on the outer side of the peripheral wall of the hub 77 to form a groove 83 along an arc centered on the axis of the shaft 72. On the other hand, a flange portion 88 is formed on the outer peripheral portion of the frame 71, and a ridge 84 along an arc centered on the axis of the shaft 72 is formed on the inner peripheral side of the flange portion 88. The groove 84 is the groove 8
A labyrinth structure is formed by fitting the gap 3 into the gap 3 with an appropriate gap. The outer peripheral surface of the small peripheral wall 86 opposes the inner surface 85 of the cylindrical peripheral wall of the frame 71 with a proper gap, and also has a labyrinth structure. Reference numeral 94 indicates a flexible board for connection with an external circuit.

In the conventional example shown in FIG. 8, as described above, the protrusions 84 of the frame 71 and the grooves 83 of the hub 77 are fitted together, and the outer peripheral surface of the small peripheral wall 86 of the hub 77 and the frame 71 are also fitted. Has a labyrinth structure by facing the inner surface 85 of the cylindrical peripheral wall with a minute gap.
Oil mist and other dust generated in the bearings 75 and 76 are blocked by the labyrinth structure portion, and the dust and the like are prevented from adhering to the hard disk.
A cap 80 is placed on the upper end opening of the hub 77 so that dust and the like from the bearings 75 and 76, which are about to go out from the upper end opening of the hub 77, are blocked by the cap 80.

Next, a conventional example shown in FIG. 9 will be described.
This conventional example is different from the conventional example shown in FIG. 8 in that the fixed shaft is integrally molded with the frame 71, and the drive magnet 79 is provided on the inner peripheral side of the peripheral wall 90 of the hub 77 with the yoke 78 interposed. Fixed points and peripheral wall 9 of hub 77
The outer peripheral surface of 0 and the inner peripheral surface of the peripheral wall 91 of the frame 71 face each other with a minute gap G1, and the stepped portion 93 provided on the inner peripheral side of the peripheral wall 91 of the frame 71 has the hub 77.
It has a labyrinth structure facing the lower end surface of the peripheral wall 90. Others are almost the same as the example of FIG. 8,
Common parts are designated by common reference numerals and description thereof is omitted.

Also in the case of the conventional example shown in FIG. 9, the bearings 75, 75 are formed by the labyrinth structure formed by the outer peripheral surface of the peripheral wall 90 of the hub 77 and the inner peripheral surface of the peripheral wall 91 of the frame 71.
Oil mist and other dust generated at 76 are blocked by the labyrinth structure portion, and dust and the like are prevented from adhering to the hard disk.

In addition, as described in Japanese Patent Publication No. 4-22297, a seal member is provided at the axial end of the bearing, and the contact members are arranged so as to face at least a part of the seal member. There is also known a labyrinth structure including a seal member and a contact member.

[0009]

Although the examples shown in FIGS. 8 and 9 each have a labyrinth structure on the outer periphery of the hub, according to the example of FIG. 8, grooves are formed on the outer periphery of the hub and the frame. Since it is necessary to form ridges and ridges, the shape is complicated and the processing cost is high. According to the example of FIG. 9, the gap G1 between the hub and the frame needs to be made as small as possible (preferably 0.1 mm or less), but for that purpose, both the hub and the frame are machined so that dimensional accuracy is strictly obtained. However, there is a drawback that the processing cost becomes high.
Further, in any of the examples shown in FIGS. 8 and 9, the hub swings due to an error in mounting the bearing and the hub, and it is necessary to determine the gap between the hub and the frame in consideration of this swing. There is a drawback in that the dust prevention effect is not perfect because it must be increased to some extent.

Further, according to the one disclosed in Japanese Patent Publication No. 4-22297, a labyrinth structure is formed by a seal member provided at an axial end portion of a bearing and a contact member facing each other so as to cover at least a part thereof. However, there is a drawback that the dust prevention effect is not perfect.

The present invention has been made in order to solve the above-mentioned problems of the prior art. It is easy to control the dimensions of parts, the processing cost is low, and it is possible to reduce the gap between the labyrinth structure parts and dust. An object of the present invention is to provide a magnetic disk drive device capable of enhancing the prevention effect.

[0012]

To achieve the above object, the present invention provides a shaft, a frame, a hub that holds a magnetic disk, and a bearing that has an inner ring fitted to the shaft and rotatably supports the hub. In the magnetic disk drive having the above, a facing member is provided on the outer peripheral surface of the bearing outer ring so as to face each other with a gap, and the gap portion forms a labyrinth in the middle of a space communicating from the inside of the bearing to the outside. I decided. A part of the facing member may face the axial end surface of the bearing or the seal member of the bearing with an appropriate gap. The facing member may be formed of a cylindrical protrusion formed on the frame or a cylindrical portion formed on the hub. An adhesive reservoir may be formed between the inner peripheral surface of the stator core fitted and fixed to the base of the frame and the outer peripheral surface of the cylindrical protrusion of the frame. A straight portion that is erected in the axial direction may be formed on the outer peripheral surface of the cylindrical protrusion of the frame.

[0013]

The function of the labyrinth is the gap between the outer peripheral surface of the bearing outer ring and the facing member. This labyrinth is in the middle of the space from the inside of the bearing to the outside, and prevents oil mist and other dust generated in the bearing from adhering to the disk held by the hub. If a part of the facing member faces the axial end surface of the bearing or the seal member of the bearing with a proper gap, this gap portion also constitutes the labyrinth, and the effect of preventing dust and the like is further improved. If the facing member is composed of the cylindrical protrusion formed on the frame or the cylindrical portion formed on the hub, it is not necessary to prepare the facing member as a separate member.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a magnetic disk drive device according to the present invention will be described below with reference to the drawings. Figure 1,
In FIG. 2, the base portion 1a of the frame 1 has a hole in the central portion, and the shaft 2 is fixed to this hole by press fitting.
The outer periphery of the upper portion of the base portion 1a has a cylindrical shape, and the stator core 3 is fixed to the cylindrical portion. The stator core 3 has a plurality of salient poles, and a drive coil 4 is wound around each salient pole. Inner rings 51, 61 of two bearings 5, 6 are fixed to the shaft 2 protruding above the frame 1,
A hub 7 is fixed to the outer rings 52, 62 of the bearings 5, 6 by press fitting or the like, and the hub 7 is rotatably supported on the fixed shaft 2 via the bearings 5, 6. The hub 7 has a cylindrical outer peripheral surface 22 and a flange portion 21 following the outer peripheral surface 22,
The hard disk fitted to the outer peripheral surface 22 is the flange portion 2
The hard disk rotates together with the hub 7 by being received by No. 1 and being clamped by an appropriate clamper fixed to the hub 7.

The hub 7 has a caulking portion 23 on the lower surface side of the flange portion 21, and the caulking portion 23 caulks the inward flange portion of the substantially cylindrical yoke 8 so that the yoke 8 is integrated with the hub 7. It is fixed. A ring-shaped drive magnet 9 is fixed to the inner peripheral side of the yoke 8, and the inner peripheral surface of the drive magnet 9 faces the tip surfaces of the salient poles of the stator core 3 with an appropriate gap. Therefore, the hub 7 and the hard disk held by the hub 7 can be rotationally driven at a predetermined speed by switching and controlling the energization of each drive coil 4 according to the rotational position of the drive magnet 9.

The lower bearing 5 of the two bearings 5 and 6 has its outer ring 5 as shown in detail in FIG.
A part of the outer peripheral surface of 2 is press-fitted into a circular inner peripheral surface 26 formed in the lower portion of the hub 7, and a part of the lower side of the outer ring 52 projects downward from the hub 7 in the drawing. The base portion 1a is integrally formed with a cylindrical protrusion 12 that rises along the outer peripheral surface of the outer ring 52 of the bearing 5. The outer peripheral surface of the cylindrical protrusion 12 is chamfered so as to have a conical shape, and the conical portion of the cylindrical protrusion 12 and the inner peripheral surface of the stator core 3 constitute the adhesive reservoir 1b. ing. By filling the adhesive agent reservoir 1b with an adhesive agent (not shown), the stator core 3 is firmly fixed to the base portion 1a. On the other hand, the inner peripheral surface of the cylindrical protrusion 12 surrounds the lower outer peripheral surface of the outer ring 52 with a relatively small gap G. The gap G is preferably 0.3 mm or less. The cylindrical protrusion 12 constitutes a member facing the outer ring 52, and the gap G is in the middle of the space communicating from the inside of the bearing 5 to the outside of the magnetic disk drive, and the space in the middle is complicated. A labyrinth that bends to make up.

Further, at both axial ends of the bearing 5,
Sealing materials 27 and 28 are attached to the outer ring 52 to reduce leakage of oil mist and other dust generated inside the bearing 5 to the outside. A similar sealing material is attached to the other bearing 6. An opposing surface 13 is formed on the frame 1 following the cylindrical protrusion 12. The facing surface 13 forms a surface at a right angle to the inner peripheral surface of the cylindrical projection 12, and faces the axially lower end surface of the bearing 5 with a gap G2 and also faces the seal member 27 of the bearing 5. . Although the gap G2 is larger than the gap G, the gap G2 also constitutes a part of the labyrinth.

The cap 1 is attached to the opening at the upper end of the hub 7.
0 is covered, and the dust from the bearings 5 and 6 trying to go out from the upper end opening of the hub 7 is cap 10
It is designed to shut off at.

According to the embodiment described above, the frame 1
Since the cylindrical protrusion 12 is formed on the outer peripheral surface of the outer ring 52 of the bearing 5 with a gap G therebetween to form a labyrinth structure, when the outer ring 52 of the bearing 5 rotates together with the hub 7. The air in the labyrinth structure portion becomes a negative pressure, and the labyrinth structure portion serves as an air curtain that prevents scattering of oil mist and other dust generated inside the bearing 5. Therefore, the number of dust scattered to the outside and adhering to the disc can be significantly reduced. Further, the cylindrical protrusion 1
Since the facing surface 13 following 2 faces the axial end surface of the bearing 5 with a gap G2 and also faces the seal member 27 of the bearing 5 to form a labyrinth structure, the effect of preventing dust and the like from scattering to the outside is also provided in this portion. Therefore, the number of dust scattered to the outside and adhering to the disc can be further effectively reduced.

In order to confirm the dust reduction effect in the above-described embodiment, there are a labyrinth structure at the outer peripheral portion of the bearing and an axial end portion of the bearing as in the above-described embodiment, and a labyrinth structure of such a bearing portion. Instead, the scattering number of dust was measured and compared with the hub having the labyrinth structure on the outer peripheral portion as in the conventional example shown in FIGS. 8 and 9. FIG. 3 shows the measurement result. The measurement was performed by mounting a disk on the hub, disposing a tube of a measuring machine on the outermost periphery of the disk, sucking in air, and counting the number of dust sucked into the tube together with air with a counter. As is clear from FIG. 3, according to the above embodiment, a remarkable dust scattering prevention effect is recognized.

As described above, according to the embodiment shown in FIGS. 1 and 2, in addition to the remarkable dust scattering prevention effect, the outer peripheral surface of the bearing 5 is originally finished with high precision according to the bearing standard. 5, only the inner peripheral surface of the cylindrical projection 12 of the frame 1 facing the outer peripheral surface of 5 should be machined with high dimensional accuracy, and the processing cost can be reduced. Further, since the labyrinth structure portion does not include a mounting error between the hub 7 and the bearing 5, it is possible to reduce the gap between the labyrinth structure portion and further enhance the dust prevention effect.

If the stator core 3 is to be fixed to the frame by adhesion, the adhesive will collect in the adhesive reservoir 1b.
If the worst occurs, it may adhere to members such as the hub 7 and the bearing 5 that face the cylindrical protrusion 12 and, in the worst case, prevent the hub base 7 and the bearing 5 from rotating. In order to eliminate such a problem, as shown in FIG. 4, a straight portion 1c that is axially raised is formed on the outer peripheral surface of the cylindrical protrusion 12, and the adhesive 99 is used by the other portion of the straight portion 1c. May be prevented from adhering to. Alternatively, as shown in FIG. 5, the chamfering amount of the outer peripheral surface of the cylindrical protrusion 12 is increased to form a sufficiently large adhesive agent reservoir 1b, and the adhesive agent 99 is sufficiently contained in the adhesive agent reservoir 1b. However, it may be attached to other members so as not to adhere to other members.

Next, another embodiment of the present invention will be described. In the embodiment shown in FIG. 6, the portion of the cap 10 in the embodiment shown in FIG. 2 is replaced with a labyrinth structure. That is, the outer ring 62 of the upper bearing 6 press-fitted into the center hole of the hub 7 has a part of the upper side projected from the center hole of the hub 7 and is press-fitted and fixed to the upper end of the fixed shaft 2 in a cup shape. The outer ring 6 is formed by the outer peripheral wall 31 of the facing member 30.
The outer peripheral surface on the upper side of 2 is surrounded with an appropriate gap, and the outer peripheral surface of the outer peripheral wall 31 of the facing member 30 is appropriately spaced from the inner peripheral surface of the cylindrical peripheral wall 24 formed at the upper end of the hub 7. It was made to face each other. A gap formed by the outer ring 62 of the bearing 6 and the outer peripheral wall 31 of the facing member 30, and the cylindrical peripheral wall 24 of the hub 7 and the outer peripheral wall 31 of the facing member 30.
The gaps formed by and are in the middle of the space communicating from the inside of the bearing 6 to the outside, respectively, and form a labyrinth. The labyrinth is also configured by the sealing member 64 attached to the axially upper end surface of the bearing 62 or the bearing 6 and the facing member 30 facing each other with an appropriate gap.

According to the embodiment shown in FIG. 6, since the respective labyrinth constituent parts prevent the dust and the like generated in the bearing 6 from scattering to the outside, the cap 10 in the embodiment shown in FIG. It can be replaced. Note that, also in the embodiment shown in FIG. 6, the labyrinth is formed by facing the outer peripheral surface of the lower bearing outer ring (not shown), as in the embodiment shown in FIGS. May be configured.

Although all of the embodiments described so far are of the shaft fixed type, the present invention can be applied to the shaft rotary type. FIG. 7 shows an example. In FIG. 7, the frame 41 integrally has a bearing holder portion 45 at the center, and the stator core 3 is provided on the outer peripheral side of the bearing holder portion 45.
However, the outer rings 52 and 62 of the two bearings 5 and 6 are fixed to the inner peripheral side of the bearing holder portion 45 by press fitting.
A drive coil 4 is wound around each salient pole of the stator core 3. The shaft 32 is press-fitted to the inner rings 51 and 61 of the two bearings 5 and 6, and the hub 34 is press-fitted to the upper end of the shaft 32 protruding from the upper bearing 6. Therefore, the shaft 32 and the hub 34 are
It is rotatably supported with respect to.

The hub 34 is formed in a cylindrical shape with a bottom, and has an outer peripheral surface 36 on which a hard disk is fitted and a flange portion 35 for receiving the hard disk. Hub 34
A drive magnet 38 is fixed to the inner peripheral side of the stator via a yoke 37, and the inner peripheral surface of the drive magnet 38 is fixed to the stator core 3
Of each of the salient poles, facing each other with an appropriate gap. Therefore, by switching the energization to the drive coil 4 according to the rotational position of the drive magnet 38, the hub 3 together with the shaft 32 can be switched.
4 is rotationally driven.

A part of the outer ring 62 of the upper bearing 6 projects from the bearing holder portion 45. On the other hand, a cylindrical surface 39 centered on the central axis of the shaft 32 is formed on the ceiling of the hub 34. The cylindrical surface 39 forms an opposing member, and constitutes a labyrinth by facing the outer peripheral surface of the outer ring 62 of the bearing 6 protruding from the bearing holder portion 45 with a proper gap. The central ceiling surface of the hub 34 opposes the axially upper end surface of the bearing 6 with a proper gap to form a labyrinth. Further, the outer peripheral surface of the flange portion 35 of the hub 34 faces the cylindrical surface 43 formed on the frame 41, and here also a kind of labyrinth is formed. A cap 40 that prevents dust from the bearing 5 from leaking to the outside is fitted into an opening at the center of the lower end of the frame 41.

Also in the axial rotation type magnetic disk drive device as shown in FIG. 7, a labyrinth is constituted by the outer peripheral surface of the outer ring 62 of the bearing 6 and the cylindrical surface 39 of the hub 34, and further, in the central portion of the hub 34. Ceiling surface and bearing 6
Since the labyrinth is formed by the axial upper end surface of the above, it is possible to greatly reduce the number of dust scattered to the outside and adhering to the disk. The same effects as those of the embodiment shown in FIGS. Play.

[0029]

According to the first aspect of the present invention, the facing member is provided on the outer peripheral surface of the bearing outer ring so as to face each other with a gap, and the gap serves as a labyrinth in the middle of the space from the inside of the bearing to the outside. , When the bearing rotates together with the hub, the air in the labyrinth structure part becomes a negative pressure, and the labyrinth structure part serves as an air curtain that prevents the scattering of oil mist and other dust generated inside the bearing. The number of dust scattered to the outside and adhering to the disc can be significantly reduced. Further, since the outer peripheral surface of the bearing is originally finished with high accuracy, only the facing member facing the outer peripheral surface of the bearing needs to be machined with high dimensional accuracy, and the processing cost can be reduced.

According to the second aspect of the present invention, in addition to the structure of the first aspect, a part of the facing member faces the axial end face of the bearing or the seal material of the bearing with a proper gap, so that it is exposed to the outside. The scattered dust can be more effectively prevented.

According to the third and fourth aspects of the invention, since the facing member is the cylindrical protrusion formed on the frame or the cylindrical portion formed on the hub, it is not necessary to add the facing member as a separate member. The number of parts can be reduced.

According to the fifth and sixth aspects of the invention, the adhesive reservoir is provided between the inner peripheral surface of the stator core fitted and fixed to the base of the frame and the outer peripheral surface of the cylindrical protrusion of the frame. In addition to forming the, the straight part that is raised in the axial direction is formed on the outer peripheral surface of the cylindrical projection that forms the adhesive reservoir, so it is possible to prevent the adhesive in the oil reservoir from adhering to the bearing or hub. it can.

[Brief description of drawings]

FIG. 1 is a front sectional view showing a main part of an embodiment of a magnetic disk drive device according to the present invention.

FIG. 2 is a front sectional view showing the entire embodiment of the above.

FIG. 3 is a comparative diagram showing the effect of the above-described embodiment, together with the conventional example, by actual measurement data of the number of dusts.

FIG. 4 is a front sectional view showing a main part of another embodiment of the magnetic disk drive according to the present invention.

FIG. 5 is a front sectional view showing a main part of still another embodiment of the magnetic disk drive according to the present invention.

FIG. 6 is a front sectional view showing a main part of still another embodiment of the magnetic disk drive device according to the present invention.

FIG. 7 is a front sectional view showing still another embodiment of the magnetic disk drive device according to the present invention.

FIG. 8 is a front sectional view showing an example of a conventional magnetic disk drive device.

FIG. 9 is a front sectional view showing another example of a conventional magnetic disk drive device.

[Explanation of symbols]

 1 frame 2 shaft 5 bearing 6 bearing 7 hub 12 cylindrical protrusion of frame 24 hub cylindrical portion 30 facing member 32 shaft 51 bearing inner ring 52 bearing outer ring 61 bearing inner ring 62 bearing outer ring

Claims (6)

[Claims] 1. A magnetic disk drive apparatus comprising a shaft, a frame, a hub for holding a magnetic disk, and a bearing having an inner ring fitted to the shaft and rotatably supporting the hub. A magnetic disk drive device having a facing member that faces the outer peripheral surface of the bearing with a gap, the gap being in the middle of a space communicating from the inside of the bearing to the outside, and forming a labyrinth. 2. The magnetic disk drive apparatus according to claim 1, wherein a part of the facing member faces the axial end surface of the bearing or the seal material of the bearing with a proper gap. 3. The magnetic disk drive device according to claim 1, wherein the facing member is a cylindrical protrusion formed on the frame. 4. The magnetic disk drive device according to claim 1, wherein the facing member is a cylindrical portion formed on the hub. 5. An adhesive reservoir is formed between an inner peripheral surface of a stator core fitted and fixed to a base portion of the frame and an outer peripheral surface of a cylindrical protrusion of the frame. The magnetic disk drive device according to claim 3. 6. The magnetic disk drive device according to claim 5, wherein a straight portion that is raised in the axial direction is formed on the outer peripheral surface of the cylindrical protrusion of the frame.