JPH1127894A - Spindle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a spindle which increases moment rigidity by extending the span of radial fluid bearings at two positions and also minimizes the leakage or scattering of a lubricant, while in use or high speed rotation in the spindles of the same dimension in height. SOLUTION: A shaft member 3 is provided on the inside circumference of a bearing member 20. A flange 5 provided on the shaft member 3 has a flat thrust-receiving surface 9, while the shaft member 3 has a cylindrical radial- receiving surface 12 at both sides of the shaft direction of the flange 5. The bearing member 20 has a thrust-receiving surface 9 which faces the thrust- receiving surface 9 and a radial bearing surface 13 facing the radial-receiving surface 12 via a radial bearing gap 8. The flange side parts of the radial bearing gap 8 at the both sides of the shaft direction of the flange 5 are communicated with each other via a communicating hole 6 provided on the shaft member 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spindle for information equipment and audio / video equipment, and particularly to a spindle most suitable for a magnetic disk drive.

[0002]

2. Description of the Related Art Conventionally, a disk spindle has a structure as shown in FIG. That is, the bearing member 51 on which the disk 50 is mounted is rotatably supported by the shaft member 54 by the two radial fluid bearings 52 and the two thrust fluid bearings 53 located above the two radial fluid bearings 52. The bearing member 51 is rotated by a motor M including a rotor 55 fixed to the bearing member 51 and a stator 56 fixed to the shaft member 54.

[0003]

In the magnetic disk drive, higher capacity and higher recording density have been developed, and the spindle motor used therein has, of course, small fluctuation of non-rotational synchronous components. In order to improve the followability of the head, it is required to reduce the axial deflection of the outer peripheral surface of the disk. A spindle using a fluid bearing is suitable for reducing the run-out of the non-rotational synchronous component, but has a disadvantage that the moment rigidity of the spindle is smaller than that of a spindle using a ball bearing. On the other hand, when the number of disks increases to increase the capacity, it is necessary to increase the moment rigidity of the spindle in order to reduce the axial runout of the disk outer peripheral surface. However, when the thrust fluid bearing 53 is arranged outside (upper side) the two radial fluid bearings 52 as shown in FIG. 3, the span between the two radial fluid bearings 52 becomes small, and the moment rigidity cannot be designed large. There is. Further, in the structure shown in FIG. 3, since the thrust fluid bearing 53 communicates with the outer surface of the spindle, there is a problem that the lubricant of the thrust fluid bearing 53 is easily scattered outward in the axial direction due to centrifugal force during rotation.

[0004] The present invention focuses on the above problems,
For spindles of the same dimensions and height, the purpose is to increase the rigidity of moment by expanding the span of the two radial fluid bearings, and to provide a spindle with less lubricant leakage and scattering during use and high-speed rotation. I have.

[0005]

A shaft member is provided on the inner periphery of a bearing member, a flange provided on the shaft member has a flat thrust receiving surface, and the shaft member has a cylindrical shape on both axial sides of the flange. The bearing member has a thrust bearing surface facing the thrust receiving surface and a radial bearing surface facing the radial receiving surface via the radial bearing clearance, and radial bearing clearances on both axial sides of the flange. Are connected to each other through a communication hole provided in the shaft member.

[0006]

FIG. 1 shows a first embodiment. Sleeves 10 are fitted and fixed to both axial ends of the inner peripheral surface of the cylindrical member 4, respectively. The pair of sleeves 10 and the cylindrical member 4 constitute a bearing member 20. The shaft member 3 is disposed on the inner periphery of the bearing member 20, and a flange 5 is provided at an axially intermediate portion of the shaft member 3. The flange 5 has a planar thrust receiving surface 9 on each of both axial sides, and the shaft member 3 has a cylindrical radial receiving surface 1 on both axial sides of the flange 5.
2 respectively. The bearing member 20 has a thrust bearing surface 11 opposed to the thrust receiving surface 9 via the thrust bearing clearance 7 and a radial bearing surface 13 opposed to the radial receiving surface 12 via the radial bearing clearance 8. Each of the radial bearing surfaces 13 is provided with a herringbone-shaped groove 25 for generating dynamic pressure. Although not shown, each of the thrust bearing surfaces 11 is provided with a herringbone-shaped groove for generating dynamic pressure. ing. The opposed radial bearing surface 13 and the radial receiving surface 12 constitute the radial fluid bearing 1, and the opposed thrust bearing surface 11 and the thrust receiving surface 9 constitute the thrust fluid bearing 2.

The shaft member 3 includes two radial fluid bearings 1.
And the bearing member 20 is rotatably supported via two thrust fluid bearings 2 provided therebetween. For this reason, since the span between the two radial fluid bearings 1 can be widened, the moment rigidity is high. The communication hole 6 provided in the shaft member 3 communicates the portion of the radial bearing clearance 8 on both sides in the axial direction of the flange 5 with the flange 5 side, and the thrust fluid bearing 2 provided on both sides of the flange 5 during use. This prevents the lubricant from leaking outward in the axial direction based on the pressure difference of the lubricant in the thrust bearing clearance 7. That is, when the communication hole 6 is not provided, when an axial load is applied downward during rotation of the bearing member 20, the pressure of the upper thrust bearing clearance 7 becomes higher than the pressure of the lower thrust bearing clearance 7 and the upper thrust bearing clearance 7 becomes higher. The lubricant in the radial bearing gap 8 leaks upward or downward until the overall pressure is balanced. Without the communication hole 6, the pressure difference between the thrust bearing clearances 7 on both sides in the axial direction of the flange 5 changes every time the axial load changes due to a change in the use posture, and the lubricant leaks out.
Although the lubricant is depleted by long-term use, the present invention can completely prevent such leakage of the lubricant.

In this embodiment, the thrust bearing surface 9 of the thrust fluid bearing 2 is provided on both axial sides of the shaft flange 5, and the sleeve 10 is provided with a thrust bearing surface 11 facing the thrust receiving surface 9. Therefore, there is an advantage that the spindle is not restricted by the use posture even when external shock or external vibration is applied. In addition, when the flange 5 is integrated with the shaft member 3, machining accuracy is improved, and a perpendicularity between the shaft center and the planar thrust receiving surface 9 of the flange 5 is easily ensured. This is preferable because it can prevent one-side contact and improve the start / stop durability.

Next, a second embodiment will be described. In FIG. 2, the flange 5 is fitted and fixed to the axially intermediate portion of the shaft 24. With the flange 5 being separate from the shaft 24, the shaft 2
4, the shaft member 3 is provided with a flange 5 and a shaft 24. Further, between the inner diameter surface of the flange 5 of the shaft member 3 and the outer diameter surface of the shaft 24, the flange 5 of the radial bearing clearance 8 on both axial sides of the flange 5 is provided.
There is provided a lubricant communication hole 6 which communicates the side portions with each other. An oil supply hole 26 communicating with the communication hole 6 is provided on one end surface of the shaft member 3. The lubrication hole 26 has a lubrication hole 26
The plug 28 is closed after the lubricant is injected into the communication hole 6 to prevent the lubricant from leaking to the outside.

Incidentally, the axial position of the rotor fixed to one of the shaft member 3 and the bearing member 20 and the axial position of the stator radially opposed to the rotor and fixed to the other of the rotor may be shifted, or an auxiliary magnetic bearing may be provided. By providing the shaft member 3 and the bearing member 20, an axial magnetic attraction force is applied to the shaft member 3 and the bearing member 20 so that an axial load is applied to only one surface of the flange 5. The receiving surface 9 can also be used. In this case, the other thrust receiving surface 9 of the flange 5 only functions as a stopper and does not receive an axial load. In this case, the magnitude of the external impact or external vibration that can withstand the use posture is restricted, but the groove for generating the dynamic pressure is formed between the thrust receiving surface 9 and the thrust bearing surface 11 in the axial direction of the flange 5. There is an advantage that it is necessary to provide only at least one of them.

The grooves for generating dynamic pressure of the thrust fluid bearing 2 have a thrust receiving surface 9 and a thrust bearing surface 1 facing each other.
1 and the grooves for generating dynamic pressure of the radial fluid bearing 1 are provided on at least one of the radial receiving surface 12 and the radial bearing surface 13 facing each other. In the present invention, the bearing member may be rotated 20 times or the shaft member may be rotated 3 times. In the present invention, since the thrust fluid bearing 2 is provided between the two radial fluid bearings 1, the lubricant of the thrust fluid bearing 2 is sealed by the radial fluid bearings provided on both sides of the thrust fluid bearing 2. Even if a centrifugal force acts during rotation, the lubricant is prevented from scattering outside the spindle, and durability is improved.

[0012]

According to the present invention, the thrust fluid bearing has two
Since the radial fluid bearings are sandwiched between the two radial fluid bearings and the span of the two radial fluid bearings can be widened, the moment rigidity of the spindle is improved, and the axial runout of the outer periphery of the spindle can be reduced. Further, since the thrust bearing clearance is sealed by the self-sealing function of the radial fluid bearing, leakage of the lubricant during use can be prevented, and the lubricant is less scattered during high-speed rotation and has excellent durability. Also, the shaft member is provided with a lubricant communication hole that communicates the flange side portion of the radial bearing clearance on both axial sides of the flange,
By reducing the pressure difference generated in the vicinity of both axial sides of the flange in use, leakage of the lubricant to the outside of the spindle is prevented.

[Brief description of the drawings]

FIG. 1 is a diagram showing a first embodiment of the present invention.

FIG. 2 is a diagram showing a second embodiment of the present invention.

FIG. 3 is a diagram showing a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Radial fluid bearing 2 Thrust fluid bearing 3 Shaft member 4 Cylindrical member 5 Flange 6 Communication hole 7 Thrust bearing clearance 8 Radial bearing clearance 9 Thrust receiving surface 10 Sleeve 11 Thrust bearing surface 12 Radial receiving surface 13 Radial bearing surface 20 Bearing member

Claims (1)

[Claims] 1. A shaft member is provided on an inner periphery of a bearing member, a flange provided on the shaft member has a planar thrust receiving surface, and the shaft member has a cylindrical shape on both axial sides of the flange. A radial bearing surface, wherein the bearing member has a thrust bearing surface facing the thrust receiving surface, and a radial bearing surface facing the radial receiving surface via a radial bearing clearance; A spindle on the flange side of the radial bearing clearance, which communicates with each other through a communication hole provided in a shaft member.