JPH05196032A - Bearing device - Google Patents

Abstract

(57) [Summary] [Object] To provide a bearing device having a groove for generating dynamic pressure, which can keep the outside of the hub clean even if fine particles of the lubricant scatter from the inside of the bearing clearance. [Structure] A shaft 1 and a sleeve 2 which is inserted therethrough are provided. The sleeve 2 is provided with cylindrical radial bearing surfaces 5 at two axially distant locations, and these two bearing surfaces 5 are provided.
An air vent hole 6 that communicates the inside and the outside of the sleeve is provided in a space between them, a shaft is provided with a groove 8 for generating dynamic pressure on a surface facing at least one bearing surface 5, and a rotor is provided on the outer peripheral side of the sleeve 2. 15 and the stator 16 are arranged so as to face each other in the radial direction, and the air vent hole 6 is provided on the outer diameter surface of the sleeve 2 and the stator 1.
6, a flow passage 18 provided between the rotor 16 and the inner surface of the rotor 6, a clearance 19 between the upper surface of the stator 16 and the bottom surface of the hub 3 fixed to the upper end of the shaft 1, and a clearance 1 between the rotor 15 and the stator 16.
7 and the lower end surface of the rotor 15 and the upper surface of the base 4 to communicate with the outside air through a gap 20.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bearing device having a groove for generating a dynamic pressure between both members of a shaft and a sleeve, and more particularly to an HDD (magnetic disk drive device) and an LBP.
The present invention relates to a bearing device suitable for use in rotary devices such as (laser beam printers) that require a high degree of cleanliness.

[0002]

2. Description of the Related Art A conventional bearing device of this type is disclosed in, for example, Japanese Patent Publication No. 63-50564. In this structure, a cylindrical bearing surface is provided at two locations distant from each other in the axial direction of the sleeve, and an air vent hole for communicating the inside and outside of the sleeve is provided at a location between the two bearing surfaces. On the other hand, the shaft is provided with a facing surface facing the bearing surface of the sleeve, and at least one of the facing surface and the bearing surface is provided with a groove for generating a dynamic pressure to lubricate oil, grease or the like. It is lubricated with an agent.

By providing the air vent hole, the air in the bearing can be released. As a result, the air repeatedly expands and contracts due to changes in the bearing temperature during operation, the internal pressure of the bearing changes, and the lubricant in the bearing gradually flows out to the outside during operation, resulting in early damage to the bearing. Can be prevented. Further, since the air easily escapes, there is an advantage that the dynamic pressure type bearing device can be easily assembled.

[0004]

However, in the above-mentioned conventional example, no consideration is given to the influence of the pollution caused by the lubricant scattered from the air vent holes with the relatively large amount of air discharged at the time of starting. At the time of start-up, there is a problem that a small amount of lubricant is scattered out of the sleeve along with the air flow flowing out from the air vent hole, and the member attached to the sleeve that requires a high degree of cleanliness is contaminated.

Therefore, the present invention has been made by paying attention to the above-mentioned conventional problems, and an object thereof is to keep the outside of the hub clean even if the fine particles of the lubricant scatter from the inside of the bearing clearance. The present invention is to provide a bearing device.

[0006]

To achieve the above object, the present invention comprises a shaft and a sleeve fitted to the shaft,
The sleeve is provided with a cylindrical bearing surface at two axially distant locations, and an air vent hole is provided at the location between the two bearing surfaces to communicate the inside and outside of the sleeve, and the shaft is provided with a bearing surface. In a bearing device in which opposing surfaces are provided and a groove for dynamic pressure generation is provided in at least one of the opposing surface and the bearing surface, the rotor and the stator are radially opposed to each other on the outer peripheral side of the sleeve. And the air vent hole is configured to communicate with the outside air through a flow passage provided between the outer diameter surface of the sleeve and the inner diameter surface of the rotor or the stator and a clearance between the rotor and the stator. did.

[0007]

The flow passage provided between the outer diameter surface of the sleeve and the inner diameter surface of the rotor or the stator and the clearance between the rotor and the stator are narrow, and the passage from the flow passage to the clearance between the rotor and the stator. Is bent. Therefore, the fine particles of the lubricant scattered from the air vent holes collide with the wall surface while passing through the flow passages and the gaps, or the fine particles collide with each other to be captured and confined inside. Therefore, it is possible to prevent the phenomenon that the lubricant flows to the outside and stains the driven body.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 3 show an embodiment of the present invention. The figure shows the bearing device of the present invention applied to a magnetic disk drive. In the figure, 1 is a shaft, and 2 is a sleeve fitted therein. The upper end of the shaft 1 is fixed to the shaft center of the bottom of the cup-shaped hub 3 which is laid down, so that the shaft 1 projects downward in the center of the hub 3. The cylindrical sleeve 2 is
The flange 2A at the lower end of the base 4 is screwed to the base 4,
It is fixed upright. Cylindrical radial bearing surfaces 5, 5 are provided on the inner peripheral surface of the sleeve 2 at two positions apart from each other in the axial direction. An air vent hole 6 that communicates the inside and outside of the sleeve 2 is provided at a location between the two bearing surfaces 5 and 5.

On the other hand, the outer surface of the shaft 1 is provided with facing surfaces, that is, radial receiving surfaces 7, 7 facing the radial bearing surfaces 5, 5. A herringbone-shaped groove 8 for generating a dynamic pressure is formed in this to form a dynamic pressure type radial bearing. A cylindrical thrust receiver 10 is fixed to the inner peripheral surface of the lower end portion of the sleeve 2 by means of press fitting or the like. A flat upper end surface of the thrust receiver 10 is a thrust bearing surface 11, and a spiral dynamic pressure generating groove 12 as shown in FIG. 2 is formed therein. The lower end surface of the shaft 1 serves as a thrust receiving surface 13 facing the thrust bearing surface 11 and constitutes a dynamic pressure type thrust bearing. An air vent hole 14 is formed on the side surface of the thrust receiver 10 as a shallow vertical groove in the axial direction.

A lubricant such as lubricating oil or grease is filled in the bearing clearance between the dynamic pressure type radial bearing and the dynamic pressure type thrust bearing. Inside the cup-shaped hub 3, a rotor 15 and a stator 16 that constitute a motor for rotational driving are installed. The rotor 15 is fixed to the inner peripheral surface of the hub 3,
On the other hand, the stator 16 is fixed to the outer diameter surface of the sleeve 2. Thus, the rotor 15 is radially opposed to the stator 16 with a slight clearance 17 between them.

Further, between the outer diameter surface of the sleeve 2 and the inner diameter surface of the stator 16 fixed to the sleeve 2, there is provided a slight clearance 18 having a width of 1 mm or less as an air flow passage. The flow passage 18 is formed by making the outer diameter of the sleeve 2 slightly smaller by the upper half of the axial length.
The air vent hole 6 penetrating the side surface of the sleeve 2 communicates with the flow passage 18. And the flow passage 18
Is a clearance 19 between the upper end surface of the stator 16 and the bottom surface of the hub 3, and a clearance 17 between the rotor 15 and the stator 16.
Also, it is configured to communicate with the outside air through a clearance 20 between the lower end surface of the rotor 15 and the upper surface of the base 4.

Between the clearance 20 and the outside, that is, the hub 3
A labyrinth seal 21 which is a non-contact seal is further provided between the lower end surface of the peripheral edge of the base and the base 4. The mounting member 2 is attached to the outer diameter surface of the hub 3 of the bearing device configured as described above.
One to a plurality of (two in the figure) magnetic disks 23 are mounted via 2. Next, the operation will be described.

When the coil of the stator 16 of the drive motor is energized, a rotational force is generated in the rotor 15. As a result, the hub 3 and the magnetic disk 23 rotate integrally with the shaft 1. By this rotation, a dynamic pressure is generated by the herringbone-shaped dynamic pressure generating groove 8 formed on the radial receiving surface 7 of the shaft 1, and the shaft 1 is moved relative to the sleeve 2 by the pressure of the lubricant in the radial bearing clearance. It is supported radially without contact. At the same time, on the lower surface of the shaft 1, dynamic pressure is generated by the spiral dynamic pressure generating groove 12 formed in the thrust bearing surface 11 of the thrust receiver 10, and the shaft 1 is moved by the pressure of the lubricant in the thrust bearing clearance. It is kept in non-contact with the thrust receiver 10 and is supported by being floated in the axial direction.

Moreover, since the lubricant is used instead of the air flow, a sufficient load capacity can be obtained even with a shaft having a small diameter. Even if a small amount of the lubricant flows out to the outside below the base 4, there is no possibility that the magnetic disk 23 located on the outer periphery of the hub 3 above the base 4 will be contaminated. On the other hand, the oil mist scattered from the air vent hole 6 collides with the inner peripheral surface of the stator 16 and is captured. Even if not all of the oil mist can be captured, most of the oil mist is captured while passing through the narrow gap 18 having a width of 1 mm or less between the shaft 1 and the stator 16. Furthermore, even after passing through this clearance 18,
Since it passes through the other clearance 19, the clearance 17, the clearance 20, the labyrinth seal 21, and the narrowly curved passage, they are caught in the middle of the passage. Therefore, it is possible to prevent the oil mist from being scattered to the space outside the hub 3 and to soil the magnetic disk 23.

FIG. 4 shows a second embodiment of the present invention.
In this embodiment, the shaft 1 is fixed and the sleeve 2 is rotated. That is, the shaft 1 is the base 4
The fixed shaft 1 is fitted and fitted with a sleeve 2. The sleeve 2 and hub 3
The rotor 15 and the rotor 15 are integrally rotatably fixed. The stator 1 arranged to face the rotor 15 in the radial direction.
6 is fixed to a rising portion 30 formed on the base 4.

Of the dynamic pressure generating grooves provided above and below the outer diameter surface of the shaft 1, the lower groove 8 is a herringbone-shaped groove as in the first embodiment, whereas the upper groove 8 is a herringbone groove. The groove 31 is a spiral groove. The upper end surface of the shaft 1 serves as a thrust receiving surface 13, and a cylindrical thrust receiver 10 having a thrust bearing surface 11 is fixed to the inner peripheral surface of the upper end portion of the sleeve 2.

The thrust bearing in this case is of a type in which the lubricating oil circulates internally, and no air vent hole is required. That is, in the vicinity of the lower end of the spiral groove 31 of the shaft 1, the shaft 1
A through hole 32 that traverses the
A circulation hole 33 is formed in the shaft center portion through the thrust receiving surface 13 at the upper end of the shaft. When the sleeve 2, the hub 3, and the rotor 15 rotate integrally around the shaft 1, the lubricant in the upper radial bearing clearance is pushed out between the thrust bearing surface 11 and the thrust receiving surface 13. As a result, the thrust bearing surface 11 is pressurized and the sleeve 2 is supported in a floating manner.
After that, the lubricant is repeatedly circulated by being pushed into the circulation hole 33. The outlet of the air vent hole 6 is connected to a slit 34 formed in the outer diameter surface of the sleeve 2 as an axial flow passage. The scattered lubricant passes through the slit 34 and then is discharged to the outside through the bent gap.

The trapping action of the scattered oil mist is substantially the same as in the case of the first embodiment. This second
According to the embodiment of the present invention, the air vent hole 1 is provided near the thrust bearing.
Since it is not necessary to provide No. 4, there is an advantage that oil mist scattering to the outside is reduced accordingly.

In each of the above-described embodiments, the case where the dynamic pressure generating groove 8 is formed in the V-shaped herringbone shape has been described, but the present invention is not limited to this, and the C-shaped herringbone shape groove may be used. Further, the thrust bearing may be a floating type such as a dynamic pressure groove bearing, or may be a floating type such as a point contact type.

Further, as the bearing unit, the case where the dynamic pressure groove bearings are used at both upper and lower positions has been described. However, a bearing unit having only one of the dynamic pressure groove bearings and the other being a rolling bearing can be used. is there. Also, the rotor 15
Alternatively, the stator 16 may be provided with a passage for venting air.

Although the labyrinth seal is provided between the peripheral edge of the hub 3 and the upper surface of the base 4, the known non-contact type seal structure may be used. or,
The dynamic pressure generating grooves 8 and 31 may be provided on the inner diameter surface of the sleeve 2, or may be provided on both the outer diameter surface of the shaft 1 and the inner diameter surface of the sleeve. Further, the dynamic pressure generating groove 12 of the dynamic pressure type thrust bearing may be provided on the end surface of the shaft 1 or may be provided on both the shaft and the thrust receiver.

The sleeve 2 and the base 4 shown in FIG. 1 may be integrated into one member, or the sleeve 2 and the hub 3 shown in FIG. 4 may be integrated into one member.

[0023]

As described above, according to the present invention,
In a bearing device in which at least one of a bearing surface of a sleeve and a shaft is provided with a groove for generating a dynamic pressure, a rotor and a stator are arranged radially opposite to each other on the outer peripheral side of the sleeve to communicate the inside and the outside of the sleeve. The air vent hole is formed so as to communicate with the outside air through the flow passage provided between the outer diameter surface of the sleeve and the inner diameter surface of the rotor or the stator and the narrow gap between the rotor and the stator. Therefore, even if the fine particles of the lubricant are scattered from the air vent hole, they are trapped while passing through the flow passage and the clearance, and the lubricant does not flow out to the driven body to provide a bearing device. can do.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing a first embodiment of the present invention.

FIG. 2 is a plan view of a dynamic pressure generating groove formed on an end surface of a thrust bearing.

FIG. 3 is an enlarged cross-sectional view of section III of FIG.

FIG. 4 is a vertical cross-sectional view showing a second embodiment of the present invention.

[Explanation of symbols]

 1 shaft 2 sleeve 3 hub 4 base 5 radial bearing surface 6 air vent hole 8,31 dynamic pressure generating groove 15 rotor 16 stator 17 clearance between rotor and stator 18 and 34 are flow passages

Claims (1)

[Claims] 1. A shaft comprising a shaft and a sleeve fitted to the shaft,
The sleeve is provided with a cylindrical bearing surface at two axially distant locations, and an air vent hole is provided at the location between the two bearing surfaces to communicate the inside and outside of the sleeve, and the shaft is provided with a bearing surface. In a bearing device in which opposing surfaces are provided, and a groove for dynamic pressure generation is provided in at least one of the opposing surface and the bearing surface, the rotor and the stator are radially opposed to each other on the outer peripheral side of the sleeve. And the air vent hole is configured to communicate with the outside air through a flow passage provided between the outer diameter surface of the sleeve and the inner diameter surface of the rotor or the stator and a clearance between the rotor and the stator. Bearing device characterized by the above.