JP2001254728A - Dynamic pressure gas bearing system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve stability and reliability of rotation on a dynamic pressure gas bearing system. SOLUTION: A shaft 4 provided with a radial direction dynamic pressure generating groove 9 on an outer peripheral surface 4b is fixed on an upper surface of a thrust flange 3 through a projected shaft part 4a. A sleeve 7 integrally provided on a hub 5 is rotatably fitted on the shaft 4, and a roughly ring type thrust bearing plate 8 fixed on the hub 5 and having a hole for passing through the projected shaft part and thrust direction dynamic pressure generating grooves 10a, 10b on an upper surface and a lower surface, is arranged so as to enter between the lower surface of the shaft 4 and the upper surface of the thrust flange 3. Rotating stability and reliability can be improved as dynamic pressure in the thrust direction is increased when the sleeve 7 is relatively rotated in relation to the shaft 4 by providing the thrust direction dynamic pressure generating grooves 11a and 11b on a thrust receiving surface 4c on the lower surface of the shaft 4 and a thrust receiving surface 3a of the thrust flange 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dynamic pressure type gas bearing device.

[0002]

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

Hereinafter, an example of the above-described conventional dynamic gas bearing device will be described with reference to FIG. 7, reference numeral 1 denotes a frame as a base on which the motor stator 2 is mounted, 3 denotes a thrust flange erected on the frame 1, and 4 denotes a shaft, which is coaxial with the upper surface of the thrust flange 3 via a small diameter projecting shaft portion 4a. Is fixed. Reference numeral 5 denotes a hub to which a motor rotor 6 is attached, and reference numeral 7 denotes a sleeve provided integrally with the hub 5, which is rotatably fitted to the shaft 4. Reference numeral 8 denotes a substantially annular thrust bearing plate fixed to the hub 5, which has a hole through which the protruding shaft portion 4 a penetrates, and is provided between the thrust receiving surface 4 c on the lower surface of the shaft 4 and the thrust receiving surface 3 a on the upper surface of the thrust flange 3. I'm in the middle. Numeral 9 is a dynamic pressure generating groove formed on the outer peripheral surface 4b of the shaft 4 to generate pressure in the radial direction, and 10a and 10b are dynamic pressure generating grooves formed on the thrust bearing plate 8 and generating pressure in the thrust direction.

The operation of the conventional hydrodynamic gas bearing device configured as described above will be described. When the motor stator 2 is energized, the hub 5 with the motor rotor 6 attached
Starts rotating in the direction of arrow B together with the sleeve 7 and the thrust bearing plate 8. At this time, the dynamic pressure generating groove 10 a provided on the upper surface of the thrust bearing plate 8 is connected to the thrust receiving surface 4 on the lower surface of the shaft 4.
c, a pressure is generated in a direction to push down the hub 5, and a dynamic pressure generating groove 10 b provided on the lower surface of the thrust bearing plate 8 generates a pressure in a direction to push the hub 5 up. The hub 5 floats and the rotational position is determined by the balance of the bidirectional force, and at the same time, the dynamic pressure generating groove 9 provided on the outer peripheral surface 4b of the shaft 4 collects gas to generate pressure in the radial direction, thereby causing the sleeve 7 to rotate. , The sleeve 7 and the thrust bearing plate 8 rotate stably without contact with the shaft 4 and the thrust flange 3.

[0005]

However, the above configuration has the following problems. Since a gas having lower viscosity than oil is used as the fluid, it is necessary to increase the thrust direction rigidity and load capacity of the bearing.

The rigidity of the bearing in the thrust direction is as follows.
It means that a load (external load) connected to the hub 5 or the like does not easily shift in the thrust direction of the hub 5 or the like with respect to an external force in the thrust direction exerted on the bearing device. Similarly, the load capacity refers to the magnitude of the external force such that the displacement of the hub 5 in the thrust direction becomes an allowable limit in design, and the load capacity includes the gas in the space between the shaft 4 and the thrust bearing plate 8 and the thrust flange 3. This substantially corresponds to the sum of the thrust pressure applied to the hub 5 by the gas in the space with the thrust bearing plate 8.

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 5 can be reduced. Thereby, the rotation stability of the hub 5 is improved.

In order to increase the rigidity and load capacity in the thrust direction at a predetermined number of revolutions in the conventional dynamic pressure gas bearing device, the area of the thrust bearing plate 8 having the dynamic pressure generating grooves 10a and 10b must be increased. Can be considered. However, the diameter of the thrust bearing plate 8 is limited by the size of the bearing device, processing accuracy, and the like, and there is a limit to the size. Therefore,
The bearing device had to increase the rigidity and load capacity within a certain size. To do this, use the axis 4 shown in FIG.
Between thrust bearing plate 8 and thrust flange 3
It is necessary to increase the pressure per unit area in order to increase the total sum of the thrust pressure generated in the space between the thrust bearing plate 8 and the thrust bearing plate 8.

[0009]

In order to solve the above problems, a hydrodynamic gas bearing device according to the present invention is provided on a top surface of a thrust flange erected on a frame, coaxially through a small diameter projecting shaft portion. A fixed shaft, a sleeve provided on the hub, and rotatably fitted to the shaft, and a hole fixed to the hub and through which the protruding shaft portion penetrates. A substantially annular thrust bearing plate inserted between a lower surface and an upper surface of the thrust flange; and a driving unit for rotating the sleeve relative to the shaft. The outer peripheral surface of the shaft and the outer surface facing the shaft. A radial dynamic pressure generating groove is provided on one of the inner peripheral surfaces of the sleeve, and both the lower surface of the shaft and the upper surface of the thrust bearing plate facing the shaft, and the upper surface of the thrust flange and the upper surface of the thrust flange. The thrust bearing plate It is characterized in that it has a thrust direction dynamic pressure generating grooves on both of the lower surface.

According to the present invention, there is provided a thrust dynamic pressure provided on both the lower surface of a shaft and the upper surface of a thrust bearing plate opposed thereto and both the upper surface of a thrust flange and the lower surface of a thrust bearing plate opposed thereto. The pressure of the gas in the thrust direction is further increased by the generated groove, so that the rigidity and the load capacity of the bearing in the thrust direction can be increased.

Further, even at a relatively low rotational speed, the sum of the pressures in the thrust direction of the gas can be made sufficiently large.
The rotation of the hub and the like is kept stable. For this reason, when the rotation of the hub or the like starts and stops, the stability of the opposing surfaces of the thrust bearing plate and the thrust flange against contact only at low rotation can be enhanced. Thereby, generation of wear powder in the thrust space can be suppressed, and the reliability of the dynamic pressure gas bearing device improves.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to FIGS. FIG. 1 shows a longitudinal section of a hydrodynamic gas bearing device according to an embodiment of the present invention, and the same parts as those in FIG. 7 are denoted by the same reference numerals. That is, 1 is a frame as a base on which the motor stator 2 is mounted, 3 is a thrust flange erected on the frame 1, and 4 is a shaft, which is coaxial with the upper surface of the thrust flange 3 via a small-diameter projecting shaft portion 4a. Fixed. Reference numeral 5 denotes a hub to which the motor rotor 6 is attached, and reference numeral 7 denotes a sleeve provided integrally with the hub 5, which is rotatably fitted to the shaft 4. Reference numeral 8 denotes a substantially annular thrust bearing plate fixed to the hub 5, having a hole through which the protruding shaft portion 4 a penetrates, and entering between the thrust receiving surface 4 c on the lower surface of the shaft 4 and the upper surface of the thrust flange 3. . 9 is the outer peripheral surface 4 of the shaft 4
The dynamic pressure generating grooves 10a, 10b provided on the thrust bearing plate 8 and generating pressure in the thrust direction are provided on the thrust bearing plate 8. here,
Thrust receiving surface 4c on the lower surface of shaft 4 and thrust flange 3
The dynamic pressure generating grooves 11a and 11b for generating pressure in the thrust direction are also formed on the thrust receiving surface 3a on the upper surface of the thrust receiving surface 3a.

The operation of the thus configured hydrodynamic gas bearing device according to one embodiment of the present invention will be described with reference to FIGS. In FIG. 1, when the motor stator 2 is energized, the hub 5 to which the motor rotor 6 is attached starts rotating in the direction of arrow A together with the sleeve 7 and the thrust bearing plate 8. At this time, the thrust bearing plate 8 shown in FIG.
And a dynamic pressure generating groove 11a provided on the thrust receiving surface 4c of the shaft 4 shown in FIG.
As a result, a pressure is generated in the meantime, and a pressure is generated in a direction to push down the hub 5. The dynamic pressure generating groove 10b provided on the lower surface of the thrust bearing plate 8 shown in FIG. 3 and the dynamic pressure generating groove 11b provided on the thrust receiving surface 3a of the thrust flange 3 shown in FIG. Pressure is generated in the direction, and the hub 5 floats by the balance of the force in both directions, and the rotational position is determined. On the other hand, pressure is generated in the radial direction by the dynamic pressure generating groove 9 provided on the outer peripheral surface 4b of the shaft 4, and the sleeve 7 and the thrust bearing plate 8 rotate stably without contact with the shaft 4 and the thrust flange 3. .

As a result, as shown in FIG. 6, the sum total (area) of the pressure in the thrust direction pressure distribution (FIG. 8) of the conventional example.
Therefore, the thrust direction rigidity and load capacity of the bearing can be increased by the provision of the thrust direction dynamic pressure generating grooves 11a and 11b in the shaft 4 and the thrust flange 3.

In this embodiment, the case where the radial dynamic pressure generating groove is provided on the shaft 4 and not on the sleeve side has been described. Conversely, the same applies to the case where the groove is provided on the sleeve side but not on the shaft side. It is.

[0016]

As described above, according to the present invention,
By providing grooves in the thrust direction dynamic pressure generating grooves not only on the upper and lower surfaces of the thrust bearing plate but also on the lower surface of the shaft and the upper surface of the thrust flange facing these surfaces, the pressure in the thrust direction is increased. The rigidity in the direction and the load capacity can be increased, and the rotation stability of the hub can be improved.

Further, since the rotation of the hub is stable even at a low rotation speed, the thrust bearing plate and the opposing surface of the thrust flange come into contact only when the rotation is low, so that the thrust bearing plate and the thrust flange are in contact with each other. Generation of wear powder in the space can be suppressed, and rotation stability and reliability can be improved.

[Brief description of the drawings]

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

FIG. 2 is a detailed top view of a thrust bearing plate according to one embodiment of the present invention.

FIG. 3 is a detailed bottom view of a thrust bearing plate according to one embodiment of the present invention.

FIG. 4 is a detailed view of the lower surface of the shaft according to the embodiment of the present invention.

FIG. 5 is a detailed top view of a thrust flange according to one embodiment of the present invention.

FIG. 6 is a diagram illustrating a distribution of pressure in a thrust direction generated in a space between a thrust bearing plate, a shaft, and a thrust flange according to an embodiment of the present invention.

FIG. 7 is a longitudinal sectional view of a conventional hydrodynamic gas bearing device.

FIG. 8 is a distribution diagram of pressure in a thrust direction generated in a space between a conventional thrust bearing plate, a shaft and a thrust flange.

[Explanation of symbols]

Reference Signs List 1 frame 2 motor stator 3 thrust flange 3a thrust receiving surface 4 shaft 4a projecting shaft portion 4b outer peripheral surface 4c thrust receiving surface 5 hub 6 motor rotor 7 sleeve 7a inner peripheral surface 8 thrust bearing plate 9 radial dynamic pressure generating grooves 10a, 10b , 11a, 11b Groove for generating dynamic pressure in thrust direction

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor ▲ Asa ▼ Takafumi Tadashi 1006 Odakadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. F-term (reference) 3J011 AA20 BA06 CA02

Claims (1)

[Claims] 1. A shaft, which is coaxially fixed via a small-diameter projecting shaft portion on an upper surface of a thrust flange erected on a frame, and a hub, which is rotatable relative to the shaft. A fitted sleeve, a substantially annular thrust bearing plate fixed to the hub, having a hole through which the protruding shaft portion passes, and being inserted between a lower surface of the shaft and an upper surface of the thrust flange; A driving means for rotating the shaft relative to the shaft, wherein one of an outer circumferential surface of the shaft and an inner circumferential surface of the sleeve facing the shaft has a radial dynamic pressure generating groove, And a thrust bearing hydrodynamic groove on both the upper surface of the thrust bearing plate and the upper surface of the thrust flange facing the lower surface of the thrust bearing plate. Dynamic pressure gas Receiving apparatus.