JP2001263341A - Dynamic pressure gas bearing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a dynamic pressure gas bearing to increase a total sum of a pressure in a thrust direction. SOLUTION: A through-hole 8 is formed in a thrust bearing plate 5. Gas boosted in a dynamic pressure generating groove 2b of a shaft 2 is guided therethrough to a recessed part 9 of a thrust flange 4 and a pressure in a thrust inner space 4a is increased.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dynamic pressure gas bearing device which is one of dynamic pressure type non-contact bearing devices.

[0002]

2. Description of the Related Art In recent years, the performance of a recording device using a disk has been improved and the data transfer speed has been increased. Therefore, a rotary motor unit used in this type of recording device has a high speed and high precision. Rotation is required, and a dynamic pressure type non-contact bearing device is being used for the rotating main shaft portion.

Hereinafter, a conventional hydrodynamic gas bearing device will be described with reference to the drawings. FIG. 4 is a cross-sectional view showing the configuration of a conventional dynamic pressure gas bearing device, and FIG. 5 is a distribution diagram of pressure in a thrust direction generated in a thrust internal space in the conventional dynamic pressure gas bearing device.

In FIG. 4, a shaft 12 is fitted into a bearing hole 13b of a cylindrical rotating hub 13, and the shaft 1 of the hub 13 is rotated.
Thrust receiving surface 12d at the lower end of shaft 12
And a substantially annular thrust bearing plate 15 whose upper surface faces each other is fixed. The shaft 12 has a protruding shaft portion 12c coaxially extending below the thrust bearing plate 15, and a thrust flange 14 whose upper surface is opposed to the thrust bearing plate 15 is fixed to the protruding shaft portion 12c. 14
Is fixed to the frame 11. 12b is a dynamic pressure generating groove for generating pressure in the radial direction, 15a and 15b are dynamic pressure generating grooves for generating pressure in the thrust direction, 16 is a motor stator, and 17 is a motor rotor.

Next, the operation of the conventional hydrodynamic gas bearing device configured as described above will be described. In FIG. 4, when the motor stator 16 is first energized, the motor rotor 17 starts rotating in the direction of arrow B together with the hub 13 and the thrust bearing plate 15. At this time, the outer peripheral surface 1 of the shaft 12
The dynamic pressure generating groove 12b of 2a collects gas, generates pressure in the radial direction, and causes the hub 13 to float. On the other hand, the dynamic pressure generating groove 15a of the thrust bearing plate 15 is
d, a pressure is generated in the direction of pushing down the hub 13, and the dynamic pressure generating groove 15 b of the thrust bearing plate 15 generates a pressure in the direction of pushing up the hub 13 in the opposite direction to generate a bidirectional force. With this balance, the rotational position of the hub 13 is determined, and the hub 13 rotates without contact.

[0006]

However, in such a configuration, since a gas having a lower viscosity than oil is used as the fluid, it is necessary to increase the rigidity in the thrust direction and the load capacity of the bearing. However, the following problems occur. The rigidity of the bearing in the thrust direction refers to the difficulty of the hub 13 or the like from shifting in the thrust direction with respect to the external force in the thrust direction exerted on the bearing device by the load (external load) connected to the hub 13 or the like. The capacity is the magnitude of the external force such that the displacement of the hub 13 in the thrust direction becomes an allowable limit in design, and is substantially equal to the sum of the thrust direction pressure exerted on the hub 13 by the gas in the thrust internal space 14a. Equivalent to.

Here, when the rigidity in the thrust direction and the load capacity of the bearing are increased, the influence of the external force of the external load on the rotation of the hub 13 can be reduced. Thereby, the hub 1
From this point of view, in order to increase the thrust direction rigidity and load capacity at a predetermined number of rotations in the conventional dynamic pressure gas bearing device, the dynamic pressure generating groove is required. It is conceivable to increase the area of the thrust bearing plate 15 having 15a and 15b. However, the diameter of the thrust bearing plate 15 is restricted by the size of the bearing device, processing accuracy, and the like, and there is a limit to the size. Therefore,
In the bearing device, it is necessary to increase the rigidity and load capacity within a certain size. In other words, in order to increase the total sum of the thrust direction pressure generated in the thrust internal space 14a, the pressure per unit area is increased. Need to be higher. However, in this conventional hydrodynamic gas bearing device, as shown in FIG. 5, the thrust direction pressure component slightly increases near the center of rotation, but decreases drastically toward the periphery, so that sufficient pressure is not obtained. There was a problem that it could not be obtained.

An object of the present invention is to solve the above-mentioned conventional problems, and an object of the present invention is to provide a hydrodynamic gas bearing device capable of increasing the total pressure in the thrust direction.

[0009]

A dynamic pressure gas bearing device according to the present invention is inserted into a rotatable hub having a cylindrical inner peripheral surface and an outer peripheral surface facing the inner peripheral surface of the hub. A shaft that enables the hub to relatively rotate, a substantially annular thrust bearing plate that is disposed axially below the hub and that receives the lower end surface of the shaft, and that is coaxial with the shaft and below the thrust bearing plate. An extending protruding shaft portion, a thrust flange fixed to the protruding shaft portion and having an upper surface facing the thrust bearing plate, and provided on at least one of an outer peripheral surface of the shaft or an inner peripheral surface of the hub facing each other, A dynamic pressure generating groove for generating a supporting force in a radial direction, at least one of an opposing surface of the thrust bearing plate and a lower end of the shaft, and at least one of an opposing surface of the thrust bearing plate and the thrust flange; And a dynamic pressure generating groove for generating a supporting force in a thrust direction, a base for fixing a lower end portion of the protruding shaft portion, and a hub rotation driving means for applying a rotational force to the hub relative to the shaft. In a dynamic pressure gas bearing device, at least one or more through holes are provided in the thrust bearing plate, and a concave portion is provided in a portion of the thrust flange facing the through hole.

According to the present invention, the through-hole provided in the thrust bearing plate guides the gas, which has been radially intensified, to the concave portion of the thrust flange, thereby increasing the pressure of the gas in the low-pressure portion of the thrust. The sum of the pressures in the directions can be increased.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view showing a configuration of a dynamic pressure gas bearing device according to an embodiment of the present invention, and FIG. 2 is a plan view of a thrust bearing plate according to an embodiment of the dynamic pressure gas bearing device of the present invention. 2A is a top view, and FIG. 2B is a rear view. FIG. 3 is a diagram showing the distribution of pressure in the thrust direction in the thrust space in the embodiment of the dynamic pressure gas bearing device according to the present invention.

In FIG. 1, a hub 3 is rotatably mounted on a shaft 2.
The shaft 2 has a protruding shaft portion 2c at a lower end thereof. A dynamic pressure generating groove 2b is provided on the outer peripheral surface 2a of the shaft 2, and the pattern of the dynamic pressure generating groove 2b is formed asymmetrically with respect to a radial line passing through the vertex of the zigzag shape. The dynamic pressure generating groove 2b may be provided on the inner peripheral surface 3b of the hub 3. A substantially annular thrust bearing plate 5 having a dynamic pressure generating groove 5a shown in FIG. 2A and having a top surface opposed to a thrust receiving surface 2d at the lower end of the shaft 2 is fixed to the hub 3. Also, the protruding shaft portion 2c
A thrust flange 4 whose upper surface is opposed to the back of a thrust bearing plate 5 having a dynamic pressure generating groove 5b shown in FIG. The thrust bearing plate 5 has at least one or more through holes 8, and a recess 9 is provided in a portion of the thrust flange 4 facing the through holes 8. Reference numeral 1 denotes a frame for fixing the thrust flange 4 and the motor stator 6. Reference numeral 7 denotes a motor rotor mounted on the hub 3 at a position facing the motor stator 6, which rotates the hub 3 and the shaft 2 to exert a relative rotational force. Means.

Next, the operation of the thus configured hydrodynamic gas bearing device will be described. In FIG. 1, first,
When the motor stator 6 is energized, the motor rotor 7 starts rotating together with the hub 3 and the thrust bearing plate 5 in the direction of arrow A. At this time, the dynamic pressure generating groove 2b provided on the outer peripheral surface 2a of the shaft 2
As a result, pressure is generated in the radial direction to cause the hub 3 to float. On the other hand, the gas in the thrust inner space 4a at the lower end of the shaft 2 which has been increased in pressure by the asymmetric pattern of the dynamic pressure generating grooves 2b is further subjected to thrust receiving by the dynamic pressure generating grooves 5a of the thrust bearing plate 5 shown in FIG. Increase the pressure between the surface 2d and the hub 3
Generates pressure in the direction of pushing down. Further, the gas at the lower end of the shaft 2, which has been pressurized by the dynamic pressure generating groove 2 b having the asymmetric pattern, is supplied to the through hole 8 provided in the thrust bearing plate 5.
Through the recess 9 of the thrust flange 4 as shown in FIG.
By the dynamic pressure generating grooves 5b of the thrust bearing plate 5 shown in FIG. 3B, pressure is further generated in the direction of pushing up the hub 3 in the reverse direction, and the rotational position of the hub 3 is determined by the balance of the bidirectional force and stably without contact. Rotate.

As described above, the provision of the through hole 8 for guiding the pressure-increasing gas to the thrust bearing plate 5 increases the pressure in the low-pressure portion,
As shown in FIG. 3, the sum of the pressures for supporting the hub 3 in the thrust direction is larger than the sum of the pressures (area) in the conventional pressure distribution in the thrust direction shown in FIG. The capacity can be increased.

As described above, according to this embodiment, the total sum of the pressures in the thrust direction of the gas can be sufficiently increased even at a relatively low rotational speed, and the rotation of the hub and the like can be stably maintained. Also, the thrust bearing plate and the opposing surface of the thrust flange, which are in contact at the start and stop of rotation of the hub and the like, are stably separated at a low rotation speed and stabilized at a predetermined position. The occurrence is suppressed,
The reliability as a hydrodynamic gas bearing device is improved.

[0016]

As described above, according to the present invention, the rigidity and load capacity of the bearing in the thrust direction can be increased, so that the total pressure in the thrust direction increases, and the stability of the rotation of the hub and the stability of the hub can be improved. The advantageous effect that the reliability can be improved is obtained.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a configuration of a dynamic pressure gas bearing device according to an embodiment of the present invention.

FIG. 2 is a plan view of a thrust bearing plate in one embodiment of the dynamic pressure gas bearing device of the present invention.

FIG. 3 is a distribution diagram of a pressure in a thrust direction generated in a space in a thrust in the embodiment of the dynamic pressure gas bearing device of the present invention.

FIG. 4 is a cross-sectional view showing a configuration of a conventional hydrodynamic gas bearing device.

FIG. 5 is a diagram of a pressure distribution in a thrust direction generated in a thrust internal space in a conventional dynamic pressure gas bearing device.

[Explanation of symbols]

 Reference Signs List 1 frame 2 shaft 2a outer peripheral surface 2b dynamic pressure generating groove 2c protruding shaft portion 2d thrust receiving surface 3 hub 3a bearing hole 3b inner peripheral surface 4 thrust flange 4a thrust inner space 5 thrust bearing plate 5a, 5b dynamic pressure generating groove 6 motor stator 7 Motor rotor 8 Through hole 9 Recess

Claims (1)

[Claims] A rotatable hub having a cylindrical inner peripheral surface, a shaft inserted so that an outer peripheral surface thereof faces an inner peripheral surface of the hub, and a shaft capable of relatively rotating the hub; A substantially annular thrust bearing plate that is arranged at a lower portion in the axial direction of the hub and receives a lower end surface of the shaft, a protruding shaft portion coaxial with the shaft and extending below the thrust bearing plate, and fixed to the protruding shaft portion, A thrust flange having an upper surface opposed to the thrust bearing plate, a dynamic pressure generating groove provided on at least one of an outer peripheral surface of the shaft or an inner peripheral surface of the hub opposed to each other, and generating a supporting force in a radial direction; At least one of the thrust bearing plate and the lower end facing surface of the shaft,
A dynamic pressure generating groove provided on at least one of the opposing surfaces of the thrust bearing plate and the thrust flange to generate a supporting force in a thrust direction; a base for fixing a lower end of the protruding shaft portion; and the hub. A hydrodynamic gas bearing device having hub rotation driving means for applying a rotational force relative to the shaft, wherein at least one or more through holes are provided in the thrust bearing plate, and the through holes of the thrust flange are provided. A hydrodynamic gas bearing device, characterized in that a concave portion is provided in a portion facing the gas bearing.