JPH0587126A - Dynamic pressure type fluid bearing device - Google Patents

Abstract

PURPOSE:To provide a dynamic pressure type fluid bearing device to be used for a hard disc device or the like, which has a slipout preventing structure with the excellent impact resistance and the oil resistance. CONSTITUTION:A dynamic pressure type fluid bearing or a pivot bearing is provided with a shaft 2 and a thrust plate 6 formed in the end surface of the shaft 2, and the lubricant is filled therein. Multiple U-shaped members 4A, 4B to be fitted in a circumferential groove provided near the free end of the shaft 2 and a ring member for covering the U-shaped members 4A, 4B from the periphery to fix them to a stage of a sleeve are provided, and a taper is provided in the inner peripheral surface opposite to the periphery of the shaft of the ring member in the direction for enlarging a diameter thereof toward a thrust plate. The deviation and the damage of the U-shaped ring to be caused by the lubricant are thereby eliminated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydrodynamic bearing which is used for a rotating main shaft portion of a hard disk or the like and has a thrust direction retaining mechanism.

[0002]

2. Description of the Related Art Recently, instead of ball bearings, thrust or radial dynamic pressure type hydrodynamic bearings which are excellent in vibration prevention performance during rotation have been used in place of ball bearings for rotating main shafts of hard disk drives and the like.

An example of a conventional hydrodynamic bearing device will be described below with reference to the drawings. FIG. 4 is a sectional view of a conventional hydrodynamic bearing device mounted on a hard disk device. Reference numeral 21 is a base, and 12 is a shaft fixed to the base 21, which has herringbone grooves 12A and 12B and a shaft end surface 12D on the outer periphery of the shaft, and a peripheral groove 12C near the shaft end surface 12D. A hub 13 having a sleeve 13A is rotatably attached to the shaft 12. Hub 1 has shaft 1
2 is provided with a step portion 13B in the vicinity of the free end thereof, and the C ring 14 made of resin or the like shown in FIG. 7 and having a spring property is in a position in which the C ring 14 does not contact the circumferential groove 12C of the shaft 12 and is engaged therewith. The C-ring 14 is provided and fixed so that its position is determined by the ring-shaped member 15 in the step portion 13B. Axis 12
A thrust plate 16 is attached to the hub 13 by a screw or the like at a position where it comes into contact with the shaft end surface 12D. A lead magnet 18 and a back yoke 17 are mounted inside the hub 13, and a motor rotor 19 is mounted on the base 21. A spiral groove 16A shown in FIG. 6 is provided on the contact surface of the shaft end surface 12D of the thrust plate 16, and the thrust lubricant 20 is lubricated as shown in FIG. Further, herringbone grooves 12A, 12B in the gap between the shaft 12 and the sleeve 13A.
A radial lubricant 22 is lubricated in the. The radial lubricant 22 is an oil having good lubricity and thermal stability, and the thrust lubricant 20 uses grease for the purpose of preventing outflow. The thrust lubricant 20 is the same as the radial lubricant 22 or has a low apparent viscosity to reduce the torque of the bearing, and various additives are added in order to exert a good lubricating performance even when the viscosity is low. I am adding. Some of these additives may contain components that deteriorate the synthetic resin.

The operation of the dynamic pressure type hydrodynamic bearing constructed as described above will be described below. First, when the motor stator 19 is energized, a rotating magnetic field is generated and the rotor magnet 18 starts rotating together with the back yoke 17, the hub 13, the C ring 14, the ring-shaped member 15, and the thrust plate 16. When the hub 13 is subjected to an impact load in FIG. 5, the hub 13 tries to come off from the shaft 12, but the C ring 14C engages with the circumferential groove 12C to prevent coming off.

[0005]

However, the above structure has the following problems. In FIG. 5, the C ring 14 is once expanded during assembly and then incorporated in the step portion 3B. Therefore, synthetic resin is used because it is a material that is soft and has excellent spring properties, but the thrust lubricant 20 in the vicinity thereof is used. As a result, the low-viscosity grease hangs down to deteriorate the material of the C ring 14, and after long-term use, the C ring 14 made of synthetic resin is damaged when an impact load is applied to the hub 13.

[0006]

In order to solve the above problems, the hydrodynamic bearing device of the present invention is divided into a plurality of units U.
The first ring-shaped member in the shape of a letter is engaged with the circumferential groove of the shaft to prevent the shaft from coming off, and the inner surface of the second ring-shaped member that supports the first ring-shaped member from the outer circumference is provided on the opposing surface of the outer circumference of the shaft. The taper is provided so that the inner diameter increases toward the thrust plate.

[0007]

According to the present invention, since the first ring-shaped member having a U-shape does not need springiness due to the above-described structure, a material having good oil resistance can be used, and the taper of the inner circumference of the second ring-shaped member can be used. This prevents the thrust lubricant from hanging down toward the second ring-shaped member and prevents the second ring-shaped member from being cracked or damaged.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A hydrodynamic bearing device according to an embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a sectional view of a hydrodynamic bearing according to an embodiment of the present invention mounted on a hard disk device. Reference numeral 1 is a base, 2 is a shaft fixed to the base 1, and has herringbone-shaped dynamic pressure generating grooves 2A and 2B and a shaft end surface 2D on the outer periphery of the shaft, and a peripheral groove 2C near the shaft end surface 2D. A hub 3 having a sleeve 3A is rotatably attached to the shaft 2. Hub 2 has shaft 2
3 has a stepped portion 3B formed near the free end of FIG.
The second ring-shaped members 4A, 4B made of metal, resin, etc. shown in FIG. 1 and divided into a plurality of U-shaped members are circumferential grooves 2C of the shaft 2.
The U-shaped first ring-shaped members 4A and 4B, which are provided in a non-contact state and in a position where they are engaged with each other, are second in the step portion 3B.
The ring-shaped member 5 is fixed so that its position is fixed. A thrust plate 6 is attached to the hub 3 by a screw or caulking process at a position where it comes into contact with the shaft end surface 2D of the shaft 2. A rotor magnet 8 and a back yoke 7 are mounted inside the hub 3, and a motor rotor 9 is mounted on the base 1. A spiral groove 6A is provided on a contact surface of the shaft end surface 2D of the thrust plate 6, and a thrust lubricant 10 is lubricated as shown in FIG. Also, the shaft 2 and the sleeve 3A
Radial lubricant 11 is applied to the herringbone-shaped dynamic pressure generating grooves 2A and 2B in the gap.

The operation of the dynamic pressure type fluid bearing constructed as described above will be described below. First, when the motor stator 19 is energized, a rotating magnetic field is generated and the rotor magnet 8 is divided into a back yoke 7, a hub 3, a plurality of U-shaped members, first ring-shaped members 4A, 4B, and a second ring-shaped member.
The ring-shaped member 5 and the thrust plate 6 start rotating.
The pressure of the radial lubricant 11 is increased by the dynamic pressure generating grooves 2A and 2B, and the sleeve 3A rotates without contact. Further, the pressure is increased on the thrust lubricant 10 by the spiral groove 6A, and the thrust plate 6 rotates without contact. 2, when the hub 3 is subjected to an impact load or the like, the hub 3 tries to come off from the shaft 2, but the U-shaped members 4A and 4B engage with the circumferential groove 2C to prevent coming off.

In the present invention, since no bending or bending stress is applied to the first ring-shaped members 4A and 4B during assembly in FIG. 2, the material is not required to have a spring property. It can be made of synthetic resin or metal. Further, as indicated by θ in the figure, the inner circumference of the second ring-shaped member 5 is tapered in the direction in which the inner diameter increases toward the thrust plate, so that when the ring-shaped member 5 is rotated by the rotation of the bearing, the shaft is rotated. The thrust lubricant 10 injected between the second ring-shaped member 5 and the second ring-shaped member 5 is conveyed upward by the centrifugal force, that is, in the direction away from the U-shaped member, and the thrust lubricant 10 is transferred to the first ring-shaped member 4A. , 4B to prevent the material from deteriorating or cracking.

As described above, according to this embodiment, since the retaining member of the bearing does not need to be springy, it can be made of a general oil resistant material, and the thrust lubricant is the retaining member. Since it is conveyed in the direction away from the first ring-shaped member, the slip-out preventing member is not deteriorated by the thrust lubricant.

The thrust bearing has the same action and effect as a general pivot bearing (not shown) having no spiral groove 6 and having a spherical surface on the shaft end face 2D.

The dynamic pressure generating grooves 2A and 2B are formed in the sleeve 3A.
It is the same even if it is processed on the inner circumference.

[0014]

As described above, according to the present invention, the outer circumference of the first ring-shaped member divided into a plurality of U-shaped members provided in engagement with the circumferential groove of the shaft is formed by the second ring-shaped member. By providing a taper on the surface of the inner circumference of the cover second ring-shaped member that opposes the shaft outer circumference, the first ring-shaped member can prevent the bearing from slipping off, and the first ring-shaped member does not require spring properties. Therefore, it is possible to configure with general oil-resistant resin, etc., and the thrust bearing lubricant is conveyed in the direction away from the first ring-shaped member by centrifugal force, so that the first ring-shaped member is deteriorated by the lubricant. It will not be damaged or damaged.

[Brief description of drawings]

FIG. 1 is a sectional view of a hydrodynamic bearing device according to an embodiment of the present invention.

FIG. 2 is a sectional view of the same main part.

FIG. 3 is a configuration diagram of a first ring-shaped member divided into U-shaped members.

FIG. 4 is a sectional view of a conventional hydrodynamic bearing device.

FIG. 5 is a sectional view of the main part of the same.

[Figure 6] Explanatory drawing of the thrust plate in the same device

FIG. 7 is an explanatory diagram of a C ring in the same device.

[Explanation of symbols]

 1 base 2 axes 2A. 2B Dynamic pressure generating groove 2C Circumferential groove 2D Shaft end surface 3 Hub 3A Sleeve 3B Steps 4A, 4B U-shaped member 5 Second ring-shaped member 5A Taper 6 Thrust plate 6A Spiral groove

Claims (1)

[Claims] 1. A shaft having one end fixed thereto, a sleeve rotatably provided at the outer periphery thereof, and a thrust plate abutting against the shaft free end face and fixed to the sleeve, the outer periphery of the shaft or the inner periphery of the sleeve being provided. Has a dynamic pressure generation groove on either side,
A peripheral groove is provided in the vicinity of the free end of the shaft and a plurality of U
A first ring-shaped member divided into character-shaped members and a second ring-shaped member that supports the first ring-shaped member from the outer periphery and is fixed to a stepped portion opened in the sleeve; A hydrodynamic bearing device in which the inner surface of the ring-shaped member facing the shaft outer periphery has a taper whose inner diameter increases toward the thrust plate, and a lubricant is applied to the thrust plate and the dynamic pressure generating groove.