JP2002005171A - Dynamic pressure bearing device and motor equipped with it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a dynamic pressure bearing device capable of preventing its thrust bearing part from lacking in the lubricating fluid and generating the specified dynamic pressure and also provide a motor equipped with such bearing device. SOLUTION: The dynamic pressure bearing device is structured so that a lubricating fluid is put fully continuously in a thrust micro-gap constituting thrust dynamic pressure bearing parts 10 and 12 and radial gaps 7 and 9 between a sleeve 6b and a shaft 4 supported capable of rotating relatively, in which the lubricating fluid in the thrust dynamic pressure bearing parts 10 and 12 flows outward in the radial direction through the action of centrifugal force, etc., to cause lacking in the lubricating fluid required in the bearing parts 10 and 12 likely generating the condition that the specified dynamic pressure is not obtained, and to hinder generation of such condition, the opposing surfaces to form the radial gaps 7 and 9 positioned outside in the radial direction of the thrust bearing parts 10 and 12 are furnished with spiral grooves as a pump working part to make pumping in the direction toward the bearing parts 10 and 12 to the lubricating fluid positioned outside in the radial direction of the bearing parts 10 and 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dynamic body in which one of a shaft body and a sleeve body having a thrust plate projecting from a shaft is rotatably supported via a dynamic pressure bearing. A pressure bearing device and a motor including the same are applied to, for example, a rotation drive motor of a recording disk.

[0002]

2. Description of the Related Art Hard disk (corresponding to a recording disk)
As for the motor such as the rotary drive motor described above, a motor using a hydrodynamic bearing device as a bearing device has been proposed for the purpose of high speed and low vibration (noise).

As a known dynamic bearing device, for example, as disclosed in Japanese Patent Application Laid-Open No. 10-339320,
A shaft having a thrust plate protruding from the shaft,
2. Description of the Related Art A bearing device is known which includes a sleeve body opposed to a shaft body via a minute gap, and the sleeve body rotatably supports the shaft body via a lubricating fluid. In this dynamic pressure bearing device, a radial dynamic pressure bearing portion (hereinafter, referred to as a radial bearing portion) is formed at a position where the shaft body and the sleeve body face in the radial direction, and the shaft body and the sleeve body face each other in the axial direction. A thrust dynamic pressure bearing portion (hereinafter, referred to as a thrust bearing portion) is formed at the portion.

In the radial bearing and the thrust bearing,
When the sleeve rotates, the lubricating fluid is boosted by the pumping action of the dynamic pressure generating grooves formed on the surfaces that make up the minute gaps between the bearings, generating dynamic pressure, which supports the radial and thrust loads. I do. The groove for generating dynamic pressure is
For example, a herringbone-shaped or spiral-shaped groove shape is often adopted so that the lubricating fluid is concentrated toward the load supporting portion.

[0005]

By the way, in the hydrodynamic bearing device having the above structure, the lubricating fluid is pumped by the dynamic pressure generating groove so that, for example, in the case of a herringbone-shaped groove, the lubricating fluid is shaped like a square. In the center of the groove, or in the case of a spiral groove, it flows toward one end of the groove, but at the same time, various forces such as centrifugal force and other unexpected external vibrations and shocks that cause the lubricating fluid to flow outward in the radial direction. Acts on the lubricating fluid. In particular,
In the case where the lubricating fluid is formed in the thrust bearing portion so as to concentrate on the radial center portion (portion where the axial load becomes large) of the minute gap corresponding to the bearing portion, the lubricating fluid is formed by the centrifugal force or the like. Comes off the bearing portion and stays in the vicinity of the outermost periphery, and a predetermined amount of lubricating fluid in the bearing portion may be insufficient and a predetermined dynamic pressure may not be obtained.

In such a state, there has been a problem in that the sleeve body becomes unstable due to abnormal contact between the opposing surfaces constituting the bearing portion, causing seizure or entrainment of air from the outside. In the case of a hydrodynamic bearing device in which a radially outer gap communicating with the minute gap of the thrust bearing communicates with the outside of the motor, the lubricating fluid of the bearing approaches the outside of the motor through this gap, so that the lubricating fluid flows to the outside of the motor. There is also a problem that the possibility of outflow and scattering is increased, and the lubricating fluid is reduced. Accordingly, there is also a problem that the inside of the gap is exposed and air is mixed into the lubricating fluid. Therefore, a motor having such a dynamic pressure bearing device cannot realize high-speed and low-vibration (noise) rotation, and cannot be applied to an application such as a hard disk drive motor.

[0007] Such a problem is not limited to the above-described motor for rotating a hard disk, but also occurs in a motor having a dynamic pressure bearing used for other purposes.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and a hydrodynamic bearing device capable of preventing a lubricating fluid from running short in a thrust bearing portion and generating a predetermined dynamic pressure. It is an object of the present invention to provide a motor provided with such a motor.

[0009]

In order to achieve the above object, a dynamic pressure bearing device according to the present invention comprises a radial gap and a thrust dynamic pressure between a shaft body and a sleeve body which are relatively rotatably supported. In a hydrodynamic bearing device in which a lubricating fluid is continuously filled in a thrust minute gap forming a bearing portion, the lubricating fluid in the thrust hydrodynamic bearing portion flows radially outward due to the action of centrifugal force or the like, In order to prevent a state in which a predetermined dynamic pressure cannot be obtained due to a shortage of lubricating fluid necessary for the bearing portion, the lubricating fluid radially outward of the thrust dynamic pressure bearing portion is directed toward the thrust dynamic pressure bearing portion. A pumping action portion for pumping in the direction is provided radially outward of the bearing portion.

[0010] The pumping action portion may be provided in the thrust minute gap which is on the same plane as the thrust dynamic pressure bearing portion, or may be continuous with a portion which is not on the same plane as the thrust dynamic pressure bearing portion, for example, the thrust dynamic pressure bearing portion. May be provided in the radial gap. The pumping action portion may be formed on at least one of the shaft body and the sleeve body constituting the minute thrust gap or the radial gap, and examples thereof include a spiral groove. Any of the pumping action portions may be any as long as the lubricating fluid acts toward the thrust dynamic pressure bearing portion when the shaft body and the sleeve body rotate relative to each other.

According to the dynamic pressure bearing device having such a configuration,
The lubricating fluid in the thrust dynamic pressure bearing portion is always held and is prevented from flowing out of the bearing device, so that the bearing performance can be maintained for a long time.

As the above dynamic pressure bearing device, for example, a structure in which one thrust plate portion of a shaft body is provided, and a thrust dynamic pressure bearing portion is formed on one of the axial surfaces of the thrust plate portion, or this thrust plate is provided. In this configuration, thrust dynamic pressure bearing portions are formed on both surfaces of the portion in the axial direction. Further, a pair of thrust plate portions of the shaft body are provided apart from each other in the axial direction, and the thrust dynamic pressure bearing portion is formed on each thrust plate portion.

Further, in order to secure a necessary load pressure in the thrust dynamic pressure bearing portion, in addition to the thrust dynamic pressure bearing portion, a lubricating fluid is continuously supplied to the bearing portion between the shaft body and the sleeve body in addition to the thrust dynamic pressure bearing portion. This includes a configuration in which a filled radial dynamic pressure bearing portion is formed.

The radial gap is related to a thrust dynamic pressure bearing portion adjacent to the radial gap. For example, the radial gap forms a lubricating fluid holding portion for replenishing the thrust dynamic pressure bearing portion with the lubricating fluid, or the lubricating fluid is supplied to the meniscus. May be formed to form a seal structure that prevents movement into the atmosphere and mixing of air, and may further form a bearing portion.

In order to achieve the above object, a motor according to the present invention is characterized in that one of the shaft body and the sleeve body of the dynamic pressure bearing device is fixed to the stationary side, and the other rotates integrally with the rotor. . According to such a motor, various motors requiring high speed and low vibration (noise), for example, a magnetic disk such as a hard disk, a magneto-optical disk, and a CD
-It can be applied to a motor for rotatingly driving an optical disk such as a ROM or a DVD, or a polygon motor used for a laser beam printer.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a first embodiment of a dynamic bearing device and a motor provided with the same according to the present invention will be described with reference to FIGS. explain. FIG. 1 is a longitudinal sectional view schematically showing a rotation drive motor of a hard disk, and FIG. 2 is a longitudinal sectional view showing an enlarged part of FIG. 1 and showing only a right half of a shaft body described later. .

A motor 1 shown in FIG. 1 includes a bracket 2 mounted on a hard disk drive (not shown), and a shaft 4 having one end fixed in a central opening 2a of the bracket 2.
And a rotor 6 rotatably supported on the shaft body 4. The rotor 6 has a cylindrical rotor hub 6a on which the recording disk D is mounted on the outer peripheral portion, and is located on the inner peripheral side of the rotor hub 6a, and is axially supported by the shaft body 4 via a minute gap for holding a lubricating fluid. And a cylindrical sleeve body 6b. A cylindrical driving magnet 8 is fixed to the inner periphery of the lower portion of the rotor hub 6a by bonding or the like, and the stator 5 is mounted on the bracket 2 so as to face the driving magnet 8 radially inward. . When the winding of the stator 5 is energized, a driving force is generated by magnetic interaction with the driving magnet 8 and the rotor 6 rotates.

The shaft body 4 has a cylindrical shaft portion 4a and a shaft portion 4a.
An upper thrust plate 4b and a lower thrust plate 4c, which are radially protruding thrust plate portions, which are fixed at upper and lower portions of the portion protruding from the bracket 2 in the axial direction. The upper thrust plate 4b has a tapered shape in which the outer peripheral surface is reduced in diameter upward, and similarly, the lower thrust plate 4c is also tapered in which the outer peripheral surface is reduced in diameter downward.

The sleeve body 6b has a first sleeve portion 6b1, which is a small-diameter sleeve portion radially opposed to a substantially central portion of the shaft portion 4a via a radial minute gap, and an axial thrust plate on the lower surface of the upper thrust plate 4b. An upper thrust support portion 6b2 facing through a minute gap, and an upper thrust plate 4b
A second sleeve portion 6b3 radially opposed to an outer peripheral surface of the lower thrust plate 4c via a radial gap 7, a lower thrust support portion 6b4 opposed to an upper surface of the lower thrust plate 4c via a small axial thrust gap, and a lower thrust plate. A third sleeve portion 6b5 is provided on the outer peripheral surface of the outer sleeve 4c in a radial direction with a radial gap 9 therebetween. The second and third sleeve portions 6b3,
6b5 corresponds to a large-diameter sleeve portion. The inner peripheral surfaces of the second and third sleeve portions 6b3, 6b5 have the same inner diameter, and are formed with spiral grooves G1, G2 as pumping action portions described later. As will be described later, in the present embodiment, the radial and thrust minute gaps are such gaps that a dynamic pressure is generated by pumping to constitute a bearing portion, and the radial gaps 7 and 9 are for holding or sealing a lubricating fluid. The gap spacing is such that it constitutes a structure, and the gap spacing between the radial and thrust minute gaps is smaller than the radial gap.

The lubricating fluid is filled in the thrust minute gap between the lower surface of the upper thrust plate 4b and the first thrust support 6b2, and the lower surface of the upper thrust plate 4b is filled with the lubricating fluid as the rotor 6 rotates. A spiral groove G3 for generating a dynamic pressure is formed, and an upper thrust bearing 10 for supporting a load in the axial direction is formed. Similarly, a thrust minute gap between the upper surface of the lower thrust plate 4c and the second thrust support portion 6b4 is filled with a lubricating fluid, and the upper surface of the lower thrust plate 4c has the rotation of the rotor 6 (the rotor 6 in FIG. 2). Is rotated in the direction of arrow R), a spiral groove G4 for generating a dynamic pressure in the lubricating fluid is formed, and a lower thrust bearing portion 12 for supporting a load in the axial direction is formed. The spiral grooves G3 and G4 are formed so that the lubricating fluid flows radially inward.

Further, the center of the shaft 4a and the first sleeve 6
The lubricating fluid is held up and down in the radial minute gap between b1 and b via an enlarged gap 14 which is slightly enlarged at the center and does not hold the lubricating fluid, and the inner peripheral surface of the first sleeve portion 6b1 has Herringbone-shaped grooves G5 and G6 for generating dynamic pressure in the lubricating fluid with the rotation of the rotor 6 are formed above and below the enlarged gap 14, and each of the upper radial bearing portion 16 and the lower portion support a radial load. Radial bearing 1
8 are configured. The herringbone-shaped groove G5
G6 has an unbalanced shape so that the lubricating fluid flows outward in the axial direction (groove G5 is upward and groove G6 is downward).

The minute gap from the upper radial bearing 16 to the upper thrust bearing 10 and the lower radial bearing 1
The lubricating fluid is substantially continuously filled in the minute gap from the lower thrust bearing 12 to the lower thrust bearing 12. Excessive lubricating fluid is applied to both ends (tapered seals described later) of the enlarged gap 14 that continues inward in the axial direction of the two radial bearings 16 and 18 and radially outward of the two thrust bearings 10 and 12. At the continuous radial gaps 7 and 9 and replenished when the amount of lubricating fluid held in each bearing portion decreases.

Each lubricating fluid is prevented from flowing out of the motor by the following seal structure. That is, radial gaps 7, 9 are provided between the outer peripheral surfaces of the upper thrust plate 4b and the lower thrust plate 4c, and the second sleeve portion 6b3 and the third sleeve portion 6b5 which are radially opposed to each other. The upper tapered seal 20 and the lower first tapered seal 22 are respectively formed to have a tapered shape expanding toward. Above the upper thrust plate 4b and below the lower thrust plate 4c, a ring-shaped upper counter plate 24 having an opening in the center of which the shaft portion 4a is loosely fitted.
And the lower counter plate 26 are fixed to the second sleeve portion 6b3 and the third sleeve portion 6b5, respectively. The lower surface of the upper counter plate 24 and the upper surface of the lower counter plate 26 have a tapered shape that is inclined outward in the axial direction. As a result, a tapered gap is formed between the upper thrust plate 4b and the upper counter plate 24 such that the axial gap increases radially inward, and the upper second tapered seal 28 is formed. Similarly, a tapered gap is formed between the lower thrust plate 4c and the lower counter plate 26 such that the gap in the axial direction expands inward in the radial direction, thereby forming the lower second tapered seal 30.

The lower portion of the upper radial bearing portion 16 and the upper portion of the lower radial bearing portion 18 are formed in a tapered shape in which a radial gap is enlarged in a direction toward the enlarged gap 14. 3 tapered seal 3
4 is constituted. A communication hole 36 communicating with the enlarged gap 14 is formed in the shaft portion 4a, and the lower second tapered seal 3 is formed.
An opening is formed in the gap forming zero and communicates with the outside of the motor.

The meniscus of the lubricating fluid when the motor 1 is stopped and during normal rotation is reduced by the tapered seals 20 and 2.
2, and formed in each of the tapered seals 32 and 34, even if the lubricating fluid moves outward in the radial direction, the surface tension of the lubricating fluid and the air pressure outside the motor balance to allow the lubricating fluid to flow further. This prevents outflow and scattering to the outside of the motor. The meniscus of each of the tapered seals 20 and 22 may move outward in the axial direction due to an increase in the volume of the lubricating fluid due to a centrifugal force, an increase in temperature, or some other action. Seal 2
A similar meniscus is formed at 8, 30 to balance the surface tension of the lubricating fluid with the external air pressure to prevent the lubricating fluid from flowing out of the motor.

In the hydrodynamic bearing device of this embodiment, a radial bearing portion and a thrust bearing portion are vertically arranged in a pair, but the upper and lower thrust bearing portions 10 and 12 have a spiral pressure groove G3. , G4, it is not possible to generate the required axial load pressure by itself, but a dynamic pressure is generated so that the lubricating fluid of the adjacent upper and lower radial bearings 16, 18 moves outward in the axial direction. Therefore, the lubricating fluid of the upper thrust bearing portion 10 and the upper radial bearing portion 16 flows so as to approach each other, and similarly, the lubricating fluid of the lower thrust bearing portion 12 and the lower radial bearing portion 18 also flows as such. . As a result, sufficient dynamic pressure is generated in the upper and lower thrust bearing portions 10 and 12 to support a predetermined load.

However, the upper and lower thrust bearings 1
The lubricating fluids at 0 and 12 are spiral grooves G3 and G
4 near the inner peripheral surfaces of the second sleeve portion 6b3 and the third sleeve portion 6b5 (outside the radial direction of the upper and lower thrust bearing portions 10 and 12) despite the radially inward flow action due to the pumping action of 4 Side). This is considered to be caused by a centrifugal force acting on the lubricating fluid when the motor 1 rotates, unexpected external vibration / impact, and the like, and furthermore, the flow action from the upper and lower radial bearings 16 and 18 is too strong. . Such an operation is assumed in advance, and the second sleeve portion 6b3 and the third sleeve portion 6b
Spiral groove G so as not to stay near the inner peripheral surface of
Although consideration has been given to setting the groove shape so that the pumping action by G3 and G4 is increased, this setting could not be ensured until now.

However, in this embodiment, the lubricating fluid held in the radial gaps 7, 9 in which the spiral grooves G1, G2 as the pumping action portions are formed,
When the motor 1 rotates, the upper and lower thrust bearings 10,
A pumping action in the direction toward 12 is applied, and this lubricating fluid flows radially inward.

As a result, the pumping action for generating the dynamic pressure in the upper radial bearing section 16 and the upper thrust bearing section 10 and the pumping action by the pumping action section are balanced, so that the upper section can be reliably moved even if centrifugal force or the like acts. And the lower thrust bearing portions 10 and 12 hold the lubricating fluid,
Predetermined bearing performance can be maintained. Further, the pumping action portion acts to flow the lubricating fluid away from the outside of the motor (the direction toward the bearing portion), so that it is possible to prevent the lubricating fluid from flowing out and scattering outside and mixing with air. Therefore, this motor 1 can be used for a long time.

Next, a second embodiment of the dynamic pressure bearing device of the present invention and a motor having the same will be described with reference to FIG.
This will be described with reference to FIG. Note that FIG. 3 shows a part of a sleeve body described later with a part removed for convenience of explanation.

A motor 41 shown in FIG. 3 has a bracket 42 having a cylindrical portion 42a forming a central opening for attaching one end to a hard disk drive (not shown), and one end in the central opening of the cylindrical portion 42a. It has a cylindrical sleeve body 44 to be fixed, and a shaft body 46 rotatably supported by the sleeve body 44. The lower end of the central opening of the cylindrical portion 42a is sealed by a disc-shaped closing member 47.

The sleeve body 44 has a hollow portion 44a extending in the axial direction at the center, a large-diameter hollow portion 44b having a larger diameter at the lower end of the hollow portion 44a, and an outer circumferential surface at the upper end of the hollow portion 44a. Tapered portion 44c whose diameter is reduced downward
Having.

The shaft body 46 has a cylindrical rotor hub portion 48 on which the recording disk D is mounted on the outer peripheral portion, and a rotor hub portion 4.
8 and a shaft portion 50 which is axially supported by the sleeve body 44 via a minute gap in which a lubricating fluid is held.

A cylindrical drive magnet 52 is fixed to the inner periphery of the rotor hub 48 by means such as bonding, and a stator 54 is mounted on the bracket 42 so as to face the drive magnet 52 in the radial direction. I have. Stator 5
When the winding No. 4 is energized, a driving force is generated by magnetic interaction with the driving magnet 52, and the shaft 46 rotates.

Further, on the lower surface of the central portion of the rotor hub portion 48, a thrust plate portion 48a opposed to the upper end surface of the sleeve body 44 with a small thrust gap therebetween, and a radial gap 55 with a tapered portion 44c of the sleeve body 44. And has a cylindrical wall portion 48b facing the same. A spiral groove G7 to be described later is formed on the inner peripheral surface of the cylindrical wall portion 48b.

The shaft portion 50 protrudes downward from a fastening portion with the rotor hub portion 48, and has a cylindrical shaft base portion 50a opposed to the inner peripheral surface of the hollow portion 44a through a radial minute gap, and a lower end portion of the shaft base portion 50a. Ring body 56 with a larger diameter
And The upper surface of the ring body 56 faces the upper surface of the large-diameter hollow portion 44b of the sleeve body 44 via a thrust gap, and the outer peripheral surface of the ring body 56 has a radial gap on the inner peripheral surface of the large-diameter hollow portion 44b. The lower surface of the ring body 56 and the lower end surface of the shaft base 50a face the upper surface of the closing body 47 via a thrust gap. Since the ring body 56 is accommodated in the large-diameter hollow portion 44b, the ring body 56 functions as a retaining means for restricting movement of the shaft body 46 in the axial direction with respect to the sleeve body 44.

As will be described later, in the present embodiment, the radial and thrust minute gaps are such gaps that a dynamic pressure is generated by pumping to form a bearing portion, and the radial and thrust gaps are formed by a lubricating fluid. The gap spacing is such that it constitutes a holding or sealing structure, and the gap spacing between the radial and thrust minute gaps is smaller than the radial gap.

The lower surface of the thrust plate 48a and the sleeve 4
The lubricating fluid is filled in the thrust minute gap between the upper end surface of the sleeve 4 and a spiral groove G8 for generating a dynamic pressure in the lubricating fluid with the rotation of the shaft body 46 on the upper end surface of the sleeve body 44. A thrust dynamic pressure bearing portion (hereinafter, referred to as a thrust bearing portion) 58 that is formed and supports a load in the axial direction is configured. The inner peripheral surface of the hollow portion 44a and the shaft base 50
The lubricating fluid is filled in the radial minute gap between the lubricating fluid and the inner peripheral surface of the hollow portion 44a, and a herringbone-shaped groove for generating a dynamic pressure in the lubricating fluid as the shaft 46 rotates. G9 is formed, and a radial dynamic pressure bearing portion (hereinafter, referred to as a radial bearing portion) 60 that supports a radial load is configured. Note that the spiral groove G8 is formed so that the lubricating fluid flows inward in the radial direction, and the herringbone-shaped groove G9 has an unbalanced shape in which the lubricating fluid flows upward in the axial direction.

Thrust bearing portion 58 and radial bearing portion 60
Are filled with the lubricating fluid substantially continuously. Excessive lubricating fluid is held in the radial gap 55 and the gaps formed in the large-diameter hollow portion 44b that are continuous with the minute gaps, and is replenished when the amount of lubricating fluid held in each bearing decreases.

Particularly, the radial gap 55 has a tapered shape which expands downward in the axial direction by the tapered portion 44c forming the radial gap 55, and a tapered seal 57 is formed. The meniscus of the lubricating fluid when the motor 41 is stopped and during normal rotation is formed in the tapered seal 57, and even if the lubricating fluid moves downward in the axial direction, the surface tension of the lubricating fluid balances with the air pressure outside the motor. Further movement of the lubricating fluid is prevented, so that outflow and scattering of the lubricating fluid to the outside of the motor are prevented. Even if the volume of the lubricating fluid increases due to centrifugal force, temperature rise, or any other action, and the meniscus is imbalanced and the lubricating fluid flows out or scatters from the radial gap 55, the bracket 4
2 can be prevented from being caught by the stepped portion 42b at the upper end of the cylindrical portion 42a and further flowing out of the motor.

The dynamic pressure bearing device of the present embodiment comprises a thrust bearing portion 58 and a radial bearing portion 60. The thrust bearing portion 58 has a dynamic pressure generating means having a spiral groove G.
8, it is not possible to generate a necessary axial load pressure by itself, but a dynamic pressure is generated so that the lubricating fluid of the adjacent radial bearing portion 60 moves upward in the axial direction. Since the lubricating fluids flow so as to approach each other, sufficient dynamic pressure is generated in the thrust bearing portion 58 to support a predetermined load.

However, for the same reason as in the first embodiment, the lubricating fluid in the thrust bearing portion 58 may flow radially outward and stay near the inner peripheral surface of the cylindrical wall portion 48b. However, the lubricating fluid in the radial gap 55 in which the spiral groove G7 serving as the pumping action portion is formed goes upward in the axial direction when the motor 41 rotates (the shaft body 46 in FIG. 3 rotates in the direction of arrow R). , And flows radially inward of the thrust bearing portion 58.

Thus, similarly to the first embodiment, the pumping action for generating the dynamic pressure in the thrust bearing portion 58 and the radial bearing portion 60 and the pumping action by the pumping action portion are balanced, and the centrifugal force and the like are reduced. Even if it acts, the lubricating fluid is reliably held in the thrust bearing portion 58, and the predetermined bearing performance can be maintained. Further, the pumping action portion acts on the lubricating fluid in a direction away from the outside of the motor (direction toward the bearing portion), so that it is possible to prevent the lubricating fluid from flowing out and scattering outside and mixing with air. Therefore, the motor 41 can be used for a long time.

The embodiments of the hydrodynamic bearing device and the motor provided with the hydrodynamic bearing device of the present invention have been described above. However, the present invention is not limited to such an embodiment, and various modifications can be made without departing from the scope of the present invention. Can be modified or modified.

For example, the pumping action portion is not limited to the spiral groove as described above as long as it allows the lubricating fluid to flow inward in the radial direction against the action of centrifugal force or the like. Good. Further, the pumping action portion is formed on only one of the surfaces facing each other, but may be formed on the other or both. Further, although the pumping action portion is formed at a portion facing radially outward on the same surface of the thrust bearing portion, it may be radially outwardly displaced from this surface. Further, the magnitude of the pumping action by the pumping action section may be equal to or greater than or less than the dynamic pressure of the bearing section, and variously set according to the force flowing outward in the radial direction. For example, a radial dynamic pressure bearing may be formed in the radial gap.

Further, as in the first embodiment, a pair of thrust bearings are formed in the shaft so as to be spaced apart from each other in the axial direction. What constitutes a bearing part may be used. Furthermore, in each configuration, the configuration may be such that the shaft body and the sleeve body are opposite on the rotating side.

[0047]

According to the dynamic pressure bearing device of the present invention, even when a force flowing radially outward due to centrifugal force or the like acts on the lubricating fluid in the thrust bearing portion during rotation, a predetermined amount is always applied to the bearing portion. Of lubricating fluid. In addition, it is possible to prevent the lubricating fluid from flowing out and scattering away from the bearing portion. Therefore, the bearing device can maintain the bearing performance for a long time. Further, if the pumping action portion is a spiral groove, a pumping force can be applied to the lubricating fluid with a relatively simple configuration. Further, according to the motor of the present invention, it can be applied to various motors requiring high speed and low vibration (noise), and can be used for a long time.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view schematically showing a dynamic bearing device according to a first embodiment of the present invention and a motor including the same.

FIG. 2 is an enlarged longitudinal sectional view showing a part of the dynamic pressure bearing device of FIG. 1;

FIG. 3 is a longitudinal sectional view schematically showing a dynamic bearing device according to a second embodiment of the present invention and a motor including the same.

[Explanation of symbols]

1,41 motor 4,46 shaft body 6b, 44 sleeve body 10,12,58 thrust bearing part 16,18,60 radial bearing part G1, G2, G7 spiral groove (pumping action part)

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3J011 AA07 BA02 BA09 CA03 CA04 JA02 KA04 MA03 MA23 MA24 5H605 BB05 BB10 BB14 BB19 CC04 DD09 EB02 EB06 EB28 5H607 AA12 BB01 BB07 BB09 BB14 BB17 BB25 CC01 DD03 GG14 DD01 BB07 GA01 GA04 GB08 JK13 JK19

Claims (9)

[Claims] An axial body having a shaft portion and a thrust plate portion projecting radially outward from the shaft portion is opposed to an axial surface of the thrust plate portion via a minute axial thrust gap. A sleeve body having a large-diameter sleeve portion radially opposed to an outer peripheral surface of the thrust support portion and the thrust plate portion via a radial gap, and a lubricating fluid continuously filled in the thrust minute gap and the radial gap. ,
A dynamic pressure generating groove is formed in one or both of the thrust plate portion and the thrust support portion opposed to the thrust minute gap, and the other one of the shaft body and the sleeve body is thrusted. A dynamic pressure bearing device comprising a thrust dynamic pressure bearing portion rotatably supported in a direction,
The thrust dynamic pressure bearing includes a pumping action portion that applies a force for pumping a lubricating fluid in a thrust minute gap or the radial gap radially outward of the thrust dynamic pressure bearing portion in a direction toward the thrust dynamic pressure bearing portion. A hydrodynamic bearing device provided radially outward of the portion. 2. The sleeve body is provided with a small-diameter sleeve portion radially opposed to the shaft portion with a radial minute gap therebetween, and the radial minute gap is filled with a lubricating fluid and the radial minute gap is provided. A radial pressure generating groove formed in one or both of the shaft portion and the small-diameter sleeve portion opposed to the shaft portion to support one of the shaft body and the sleeve body rotatably in the radial direction. The dynamic pressure bearing device according to claim 1, wherein a dynamic pressure bearing portion is formed. 3. A shaft body having a shaft portion and a pair of axially spaced thrust plate portions protruding radially outward from the shaft portion, and an axial surface of both thrust plate portions. A sleeve body having a pair of large-diameter sleeve portions opposed to each other via a radial gap in a radial direction on a pair of thrust support portions and an outer peripheral surface of the both thrust plate portions opposed to each other via a minute axial gap, respectively, The lubricating fluid continuously filled in the thrust minute gap and the radial gap respectively related to the thrust plate part in the two thrust plate parts, and the thrust plate parts respectively opposed to the two thrust minute gaps A dynamic pressure generating groove is formed in one or both of the thrust support portion, and the other of the shaft body and the sleeve body is rotated in the thrust direction with respect to one of the shaft body and the sleeve body. A dynamic pressure bearing device comprising a pair of thrust dynamic pressure bearing portions to be supported at the same time, wherein the lubricating fluid in the thrust minute gap or the radial gap radially outward of the two thrust dynamic pressure bearing portions is A hydrodynamic bearing device, wherein a pumping action portion for applying a pumping force in a direction toward the thrust bearing portion is provided radially outward of the thrust bearing portion. 4. The sleeve body is provided with a small-diameter sleeve portion opposed to the shaft portion in a radial direction with a radial minute gap therebetween, and the radial minute gap is filled with a lubricating fluid and the radial minute gap is provided. A radial pressure generating groove formed in one or both of the shaft portion and the small-diameter sleeve portion opposed to the shaft portion to support one of the shaft body and the sleeve body rotatably in the radial direction. The dynamic pressure bearing device according to claim 3, wherein a dynamic pressure bearing portion is formed. 5. A substantially cylindrical sleeve body having a hollow portion in the axial direction, a shaft portion inserted into the hollow portion, and a thrust opposed to one axial surface of the sleeve body via a small thrust gap. A shaft body having a plate portion and a cylindrical wall portion facing an outer peripheral surface of one axial surface of the sleeve body via a radial gap, and lubrication continuously filled in the thrust minute gap and the radial gap. And a fluid, and a dynamic pressure generating groove is formed in one or both of one axial surface of the sleeve body and the thrust plate portion facing the thrust minute gap, so that the sleeve body and the shaft body A dynamic pressure bearing device comprising a thrust dynamic pressure bearing portion that rotatably supports the other in the thrust direction with respect to one,
The thrust dynamic pressure is applied to a lubricating fluid in the minute thrust gap or the radial gap radially outward of the thrust dynamic pressure bearing portion by applying a pumping force in a direction toward the thrust dynamic pressure bearing portion. A hydrodynamic bearing device provided radially outward of a bearing portion. 6. The shaft portion opposes the inner peripheral surface of the hollow portion of the sleeve via a radial minute gap that is continuous with the thrust minute gap, and the radial minute gap is filled with a lubricating fluid. A dynamic pressure generating groove is formed in one or both of the inner peripheral surface of the hollow portion of the sleeve body and the shaft portion facing the radial minute gap, and the other is formed with respect to one of the shaft body and the sleeve body. 6. A radial dynamic pressure bearing portion for supporting the shaft rotatably in the radial direction.
The hydrodynamic bearing device according to the above. 7. The radial gap is expanded so as to increase in radial dimension as it is further away in the axial direction from the adjacent thrust minute gap, and is continuously filled in the thrust minute gap and the radial gap. 7. The hydrodynamic bearing device according to claim 1, wherein a meniscus of the lubricating fluid is formed in the radial gap. 8. The spiral acting groove formed on at least one of the opposing surfaces forming the minute thrust gap radially outward of the thrust bearing portion or the opposing surface forming the radial gap from the thrust bearing portion. The dynamic pressure bearing device according to any one of claims 1 to 7, wherein the dynamic pressure bearing device is formed by a spiral groove formed on at least one side. 9. A dynamic pressure bearing device according to claim 1, wherein one of the shaft body and the sleeve body is fixed to a stationary side, and the other is integrally rotated with a rotor. Motor using a dynamic bearing device.