JP2001041243A - Hydrodynamic bearing and spindle motor having it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress sliding abrasion and to improve impulse resistance by containing micro particles with size smaller than a clearance formed with a shaft and a sleeve in lubricating oil filled into a bearing. SOLUTION: A clearance R is radially provided between a shaft 5 and a sleeve 6, lubricating oil 4 is filled into a bearing, and this contains micro particles 1 with size smaller than the clearance R. At this time, the shaft 5 and the sleeve 6 respectively come into contact with the micro particles 1, and the micro particles 1 circulate in the bearing, so that the micro particles 1 related to the contacts with the shaft 5 and the sleeve 6 always exchange with each other, and contact points depend on the circulation movement of the micro particles 1. Therefore, the sliding track of the surface of the shaft 5 and the inner peripheral surface of the sleeve 6 are not always same, and abrasion resistance can be improved. The micro particles 1 can cool heat occurring by contact of the micro particles 1 on the entire surface, prevent thermal degradation of the lubricating oil 4 to extend service life, and improve impulse resistance.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brushless motor (hereinafter abbreviated as "motor") mainly used for a magnetic disk drive, and more particularly to a dynamic bearing structure thereof.

[0002]

2. Description of the Related Art In recent years, with high capacity, high speed, high accuracy, and low noise of HDD devices in the OA field, high accuracy has been strongly required for a motor for driving a magnetic disk. As a technique, the use of a dynamic pressure bearing in a bearing structure provided between a rotor and a stator has been studied.

This dynamic pressure bearing is disclosed, for example, in Japanese Patent Application Laid-Open No. H11-55
As disclosed in Japanese Patent Publication No. 898, an example is disclosed in which a shaft supporting a rotor is inserted into a sleeve fixed to a stator, and a space between the sleeve and the shaft is filled with lubricating oil. And the radial load is
The dynamic pressure generating groove provided in the sleeve supports the radial load of the rotor by utilizing the dynamic pressure generated when the motor is driven. On the other hand, the load in the thrust direction is to support the load in the thrust direction of the rotor by point contact between the thrust plate and the spherical surface of the shaft end by the pivot bearing structure.

FIG. 6 shows an example of a conventional dynamic pressure bearing. A shaft 5 attached to a rotor (not shown) of the motor is inserted into a sleeve 6 fixed to a stator (not shown). A thrust plate 8 is provided on the sleeve 6, and a dynamic pressure generating groove 7 is provided on a side surface of the shaft 5 or an inner peripheral surface of the sleeve 6 facing the thrust plate 8. The shaft 5 and the sleeve 6 are provided with a gap R in the radial direction (2 in diameter).
R) is provided, and a gap between the shaft 5, the sleeve 6, and the thrust plate 8 is filled with the lubricating oil 4.

By configuring the dynamic pressure bearing in this way, the load in the radial direction is supported by utilizing the pressure generated in the dynamic pressure generating groove 7 generated by rotating the rotor when the motor is driven. Supports the load by making point contact with the thrust plate 8 at the spherical surface at the end of the shaft.

[0006]

However, such a dynamic pressure bearing has the following disadvantages.

First, there is a problem of wear due to contact between the shaft 5 and the sleeve 6. When the motor is turned on and off by operating the magnetic disk drive, the shaft 5 of the motor repeatedly rotates and stops, and the shaft 5 and the sleeve 6 come into contact repeatedly. ON-OF for the motor of the magnetic disk drive
The number of F times is required to be tens of thousands, and if the shaft 5 and the sleeve 6 are repeatedly contacted and slid tens of thousands of times, wear occurs at the contact portion of the shaft 5 or the sleeve 6. If the shaft 5 or the sleeve 6 is worn in this way, the bearing rigidity in the radial direction is insufficient, so that the rotor load cannot be supported, and problems such as a large whirling of the rotor occur.

[0008] The second point is a problem of impact resistance of the dynamic pressure bearing. Information devices have been required to be smaller, thinner and lighter, and portability has recently been particularly demanded. If there is an act of carrying, it may inevitably fall, so that there is inevitably a requirement for impact resistance. Although the dynamic pressure bearing generally has better impact resistance than the ball bearing due to the shock absorbing effect of the lubricating oil 4, the shaft 5 and the inner peripheral surface of the sleeve 6 collide when an impact is applied. This could cause the bearing to lock.

The third problem is that it is difficult for the motor rotor to discharge static electricity. Shaft 5 and sleeve 6
Generates heat when contacting. If the number of times of the contact sliding reaches tens of thousands of times, abrasion powder due to the sliding between the shaft 5 and the sleeve 6 adheres to the inner peripheral surface of the sleeve 6 and the sliding portion of the shaft 5 and the sleeve 6 is lubricated. An adsorbent film is formed, and the lubricating oil 4 is degraded by heat generation due to heat deterioration.
Generates sludge inside. Due to these factors, the conductivity between the shaft 5 and the sleeve 6 is lost. In the case of a motor equipped with a magnetic disk, if the static electricity charged in the rotor cannot be discharged, a discharge breakdown may occur between the magnetic disk and the recording / reproducing head, and the magnetic disk drive may be destroyed. was there.

One method for discharging static electricity from a rotor of a motor mounted on a magnetic disk drive so as not to damage a recording / reproducing head is disclosed in Japanese Patent Laid-Open No. 11-13222.
No. 5 discloses this. The embodiment is cited in FIG. This is because the thrust bearing 15 is made of synthetic resin,
By setting the volume resistivity of this resin to 108 Ω · cm or less, the static electricity charged by the rotor can be dissipated to the thrust bearing 1.
5 is discharged.

However, in this case, the end surface of the shaft 5 is supported by a spherical surface provided on the thrust bearing portion 15. An adsorbing film is formed on the sliding portion by a lubricating action on the spherical surface supporting the load in the thrust direction. Due to the effect of the adsorption film, wear and heat generation of the bearing portion are suppressed as much as possible.
Further, in the thrust bearing portion 15, abrasion powder generated in the radial bearing portion settles, and also, abrasion powder generated in the thrust bearing portion itself is likely to accumulate. Therefore, at the point contact portion of the thrust bearing portion 15, adhesion of the adsorbing film generated by the lubricating action and accumulation of wear powder generated by sliding occur.
As time elapses, the conductivity of the spherical contact portion of the thrust bearing 15 may be lost.

A thrust bearing portion 15 made of resin
Are in point contact and support the load in the thrust direction,
The resin at the point contact portion may be deformed by the impact application. If the resin of the thrust bearing portion 15 is deformed due to the impact load, the relative positional relationship between the magnetic disk and the recording / reproducing head is shifted before and after the impact, and the data recorded on the magnetic disk before the impact is reproduced after the impact is applied. Had the possibility that it would not be possible.

SUMMARY OF THE INVENTION The present invention has been made to solve such a conventional problem and suppresses the sliding wear of a shaft and a sleeve of a dynamic pressure bearing, and improves the shock resistance of a magnetic disk drive.
An object of the present invention is to realize a dynamic pressure bearing capable of discharging static electricity charged in a rotor and a spindle motor equipped with the dynamic pressure bearing.

[0014]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, a dynamic pressure bearing according to the present invention is characterized in that lubricating oil filled in the bearing contains fine particles smaller than a gap formed by a shaft and a sleeve or smaller than the gap. And a linear member bent in an arbitrary shape (hereinafter abbreviated as a linear member) or a linear member smaller than the gap and bent in a helical shape (hereinafter abbreviated as a helical linear member) And
The shaft, the sleeve, the fine particles, the linear member, and the spiral linear member are made of a conductive material.

[0015]

Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1) FIGS. 1A and 1B show a hydrodynamic bearing according to a first embodiment of the present invention.

In FIG. 1A, a shaft 5 is inserted into a sleeve 6, a thrust plate 8 is fixed to the sleeve 6, and a dynamic pressure generating groove 7 is formed in the shaft 5. A gap R is formed between the shaft 5 and the sleeve 6 in the radial direction.
have. The inside of the bearing is filled with a lubricating oil 4, and the lubricating oil 4 is configured to contain fine particles 1 smaller than the gap R as shown in FIG.

The thus configured dynamic pressure bearing supports a load in the radial direction by the dynamic pressure generated by the dynamic pressure generating groove 7 formed on the shaft 5 when the motor is driven, and the shaft end spherical surface and the thrust plate 8 are supported. Supports the load in the thrust direction by a thrust bearing constituted by point contact.

When the fine particles 1 are contained in the lubricating oil 4 as shown in FIG. 1A, the number of times that the shaft 5 and the sleeve 6 come into direct contact with each other and slide when the motor is turned on and off is reduced. That is, since the fine particles 1 are interposed between the shaft 5 and the sleeve 6, the fine particles 1 come into contact with the shaft 5, and the fine particles 1 come into contact with the sleeve 6. Since the fine particles 1 circulate inside the bearing, the fine particles 1 interposed at the time of contact between the shaft 5 and the sleeve 6 are always replaced. Further, the contact point is also adapted to the circulating movement of the fine particles 1, and the sliding trajectory between the surface of the shaft 5 and the inner peripheral surface of the sleeve 6 is not always the same, so that the wear resistance of the bearing portion can be improved. Further, the fine particles 1 interposed between the shaft 5 and the sleeve 6 at the time of the contact can cool the heat generated by the subsequent contact using the entire surface in the lubricating oil 4, and the temperature of the sliding portion increases. , It is possible to prevent the thermal deterioration of the lubricating oil 4.

Further, when an impact is applied to the motor, the shaft 5
When the fine particles 1 are interposed between the shaft 5 and the sleeve 6, the shaft 5
And the sleeve 6 can be prevented from colliding with each other, and the occurrence of scratches such as dents inside the bearing can be prevented.

Therefore, the number of times the shaft 5 contacts and slides on the sleeve 6 can be reduced to improve the wear resistance of the bearing portion and prevent the lubricating oil 4 from being thermally degraded. Problems such as rotation unevenness, shaft inclination, shaft runout, and the like can be prevented, and the life of the bearing portion can be extended. Further, the impact resistance of the bearing portion can be improved.

In the present embodiment, the dynamic pressure generating groove 7 is formed on the side surface of the shaft. However, the same applies when the dynamic pressure generating groove 7 is formed on the inner peripheral surface of the sleeve facing the shaft side surface. The effect is obtained. Further, a thrust bearing is formed by the point contact between the spherical surface of the shaft end face and the thrust plate 8, but the shaft end face is flat and the thrust plate 8 is formed.
The same effect can be obtained even in the case of a thrust bearing of the type in which a dynamic pressure generating groove is formed and floated.

(Embodiment 2) FIGS. 2A and 2B show a dynamic pressure bearing according to a second embodiment of the present invention.

In FIG. 2A, a shaft 5 is inserted into a sleeve 6, a thrust plate 8 is fixed to the sleeve 6, and a dynamic pressure generating groove 7 is formed in the shaft 5. A gap R is formed between the shaft 5 and the sleeve 6 in the radial direction.
have. The inside of the bearing is filled with a lubricating oil 4, and the lubricating oil 4 is configured to contain a linear member 2 that is smaller than the gap R as shown in FIG.

The thus configured dynamic pressure bearing supports a load in the radial direction by dynamic pressure generated by a dynamic pressure generating groove 7 formed on the shaft 5 when the motor is driven, and a shaft end spherical surface and a thrust plate 8 are supported. Supports the load in the thrust direction by a thrust bearing constituted by point contact.

As shown in FIG. 2A, the lubricating oil 4
When the motor is turned on and off, the number of times that the shaft 5 and the sleeve 6 directly contact and slide when the motor is turned on and off is reduced. That is, since the linear member 2 is interposed between the shaft 5 and the sleeve 6, the shaft 5 and the linear member 2 come into contact with each other, and the sleeve 6 and the linear member 2 come into contact with each other. Since the linear member 2 circulates inside the bearing, the linear member 2 interposed at the time of contact between the shaft 5 and the sleeve 6 is always replaced. Also,
The contact point is also adapted to the circulating movement of the linear member 2, and the sliding trajectory between the surface of the shaft 5 and the inner peripheral surface of the sleeve 6 is not always the same, so that the wear resistance of the bearing portion can be improved. Further, the linear member 2 interposed between the shaft 5 and the sleeve 6 at the time of the contact can efficiently cool the heat generated by the subsequent contact in the lubricating oil 4 by using the entire surface thereof, It is possible to prevent the thermal deterioration of the lubricating oil 4 by suppressing the temperature rise of the portion.

Further, when an impact is applied to the motor, the shaft 5
When the linear member 2 is interposed between the shaft member 5 and the sleeve 6, the collision between the shaft 5 and the sleeve 6 is prevented, and the occurrence of scratches such as dents inside the bearing can be prevented. In addition, the linear member 2 having such a shape collapses and deforms when an impact is applied, so that the impact can be alleviated and absorbed, and damage to the bearing portion can be reduced.

Therefore, the number of times the shaft 5 contacts and slides on the sleeve 6 can be reduced to improve the wear resistance of the bearing portion and prevent the lubricating oil 4 from being thermally degraded. Problems such as rotation unevenness, shaft inclination, shaft runout, and the like can be prevented, and the life of the bearing portion can be extended. Further, the impact resistance of the bearing portion can be improved.

In the present embodiment, the dynamic pressure generating groove 7 is formed on the side surface of the shaft. However, the same applies to the case where the dynamic pressure generating groove 7 is formed on the inner peripheral surface of the sleeve facing the shaft side surface. The effect is obtained. Further, a thrust bearing is formed by the point contact between the spherical surface of the shaft end face and the thrust plate 8, but the shaft end face is flat and the thrust plate 8 is formed.
The same effect can be obtained even in the case of a thrust bearing of the type in which a dynamic pressure generating groove is formed and floated.

(Embodiment 3) FIGS. 3 (a) and 3 (b) show a dynamic pressure bearing according to a third embodiment of the present invention.

In FIG. 3A, a shaft 5 is inserted into a sleeve 6, a thrust plate 8 is fixed to the sleeve 6, and a dynamic pressure generating groove 7 is formed in the shaft 5. A gap R is formed between the shaft 5 and the sleeve 6 in the radial direction.
have. The inside of the bearing is filled with lubricating oil 4, and the lubricating oil 4 is configured to contain the spiral linear member 3 smaller than the gap R as shown in FIG.

The thus configured dynamic pressure bearing supports the radial load by the dynamic pressure generated by the dynamic pressure generation groove 7 formed on the shaft 5 when the motor is driven, and the shaft end spherical surface and the thrust plate 8 are supported. Supports the load in the thrust direction by a thrust bearing constituted by point contact.

When the spiral linear member 3 is contained in the lubricating oil 4 as shown in FIG. 3A, the number of times that the shaft 5 and the sleeve 6 come into direct contact with each other and slide when the motor is turned on and off is reduced. That is, since the spiral linear member 3 is interposed between the shaft 5 and the sleeve 6, the shaft 5 and the spiral linear member 3 are in contact with each other, and the sleeve 6 and the spiral linear member 3 are in contact with each other. Since the helical linear member 3 circulates inside the bearing, the helical linear member 3 interposed at the time of contact between the shaft 5 and the sleeve 6 is always replaced. In addition, the contact point also matches the circulating movement of the helical linear member 3, and the sliding trajectory between the surface of the shaft 5 and the inner peripheral surface of the sleeve 6 is not always the same. Can be. Further, the helical linear member 3 interposed between the shaft 5 and the sleeve 6 at the time of contact can efficiently cool the heat generated by the subsequent contact in the lubricating oil 4 using the entire surface, By suppressing the temperature rise of the sliding portion, it is possible to prevent the thermal deterioration of the lubricating oil 4.

Further, when an impact is applied to the motor, the shaft 5
When the helical linear member 3 is interposed between the shaft 5 and the sleeve 6, the collision between the shaft 5 and the sleeve 6 is prevented, and the occurrence of scratches such as dents inside the bearing can be prevented. In addition, the spiral linear member 3 having such a shape can lose its shape by absorbing and absorbing shock because the shape is deformed and collapsed when an impact is applied, and the spiral linear member 3 has a regular spiral shape. , It is excellent in productivity and practicality.

Therefore, it is possible to improve the wear resistance of the bearing part by reducing the number of times the shaft 5 slides in contact with the sleeve 6 and to prevent the thermal deterioration of the lubricating oil 4. Problems such as rotation unevenness, shaft inclination, shaft runout, and the like can be prevented, and the life of the bearing portion can be extended. Further, the impact resistance of the bearing portion can be improved.

In this embodiment, the dynamic pressure generating groove 7 is formed on the side surface of the shaft. However, the same applies when the dynamic pressure generating groove 7 is formed on the inner peripheral surface of the sleeve facing the side surface of the shaft. The effect is obtained. Further, a thrust bearing is formed by the point contact between the spherical surface of the shaft end face and the thrust plate 8, but the shaft end face is flat and the thrust plate 8 is formed.
The same effect can be obtained even in the case of a thrust bearing of the type in which a dynamic pressure generating groove is formed and floated.

(Embodiment 4) FIG. 4 shows a spindle motor equipped with a dynamic pressure bearing according to a fourth embodiment of the present invention. FIG. 4 is a sectional view thereof.

Referring to FIG. 4, there is provided a stator core 9 having a stator coil for generating a magnetic field in an excited state, and a rotor having a rotor magnet 10 for obtaining a rotational force by electromagnetic interaction with the magnetic field of the stator coil. The shaft 5 supporting the rotor and the sleeve 6 supporting the shaft 5 are made of a conductive material. A dynamic pressure generating groove 7 is formed on the side surface of the shaft 5, and constitutes a radial bearing with the opposite sleeve 6. The thrust plate 8 is fixed to the sleeve 6 and forms a thrust bearing by making point contact with the spherical surface of the shaft end facing the thrust plate 8. Lubricating oil 4 is filled inside the bearings constituting the radial bearing and the thrust bearing, and the lubricating oil 4 contains a large number of fine particles 1 that are smaller than the gap R between the shaft 5 and the sleeve 6 and are a conductive material. . The shaft 5 supports a hub 11 made of a conductive material, and a magnetic disk 12 is mounted on the hub 11. Reading and writing to the magnetic disk 12 is performed by a recording / reproducing head 13, and the sleeve 6 is installed on a housing 14 of the magnetic disk drive. The housing 14 is a conductive material, and aluminum is often used.

As described above, when the fine particles 1 are contained in the lubricating oil 4, first, when the motor is turned on and off, the shaft 5
And the number of times the sleeve 6 slides in direct contact is reduced.
That is, since the fine particles 1 are interposed between the shaft 5 and the sleeve 6, the fine particles 1 come into contact with the shaft 5, and the fine particles 1 come into contact with the sleeve 6. Since the fine particles 1 circulate inside the bearing, the fine particles 1 interposed at the time of contact between the shaft 5 and the sleeve 6 are always replaced. In addition, the contact point is also adapted to the circulating movement of the fine particles 1, and the sliding trajectory between the surface of the shaft 5 and the inner peripheral surface of the sleeve 6 is not always the same, so that the wear resistance of the bearing portion can be improved. Further, the fine particles 1 interposed between the shaft 5 and the sleeve 6 at the time of the contact make the heat generated at the subsequent contact the lubricating oil 4.
It is possible to cool using the entire surface in the inside, and it is possible to prevent thermal deterioration of the lubricating oil 4 by suppressing a rise in the temperature of the sliding portion.

Second, the shock resistance of the motor can be improved. That is, when the impact is applied to the motor, the shaft 5
Since the collision of the shaft 5 with the sleeve 6 can be prevented when the fine particles 1 are interposed between the shaft 6 and the sleeve 6, it is possible to prevent the occurrence of scratches such as dents inside the bearing, and to avoid locking of the bearing portion. Can be.

Third, discharge breakdown of the recording / reproducing head can be prevented. That is, when the rotor of the motor is electrostatically charged due to the fact that the fine particles 1, the shaft 5 and the sleeve 6 are conductive materials, the static electricity can be discharged from the shaft 5 to the sleeve 6 and the housing 14 via the fine particles 1. This makes it possible to prevent the recording / reproducing head 13 from being destroyed by discharge due to static electricity.

Therefore, the number of times the shaft 5 contacts and slides on the sleeve 6 can be reduced to improve the wear resistance of the bearing portion and prevent the lubricating oil 4 from being thermally degraded. Problems such as rotation unevenness, shaft inclination and shaft runout can be prevented, and the life of the bearing can be extended. Also, while improving the shock resistance of the motor,
When the rotor is charged with static electricity, it can be discharged quickly, so that the recording / reproducing head 13 can be prevented from being destroyed due to static electricity.

In the present embodiment, the dynamic pressure generating groove 7 is formed on the side surface of the shaft. However, the same applies to the case where the dynamic pressure generating groove 7 is formed on the inner peripheral surface of the sleeve facing the side surface of the shaft. The effect is obtained. Further, a thrust bearing is formed by the point contact between the spherical surface of the shaft end face and the thrust plate 8, but the shaft end face is flat and the thrust plate 8 is formed.
The same effect can be obtained even in the case of a thrust bearing of the type in which a dynamic pressure generating groove is formed and floated.

(Embodiment 5) FIG. 5 shows a spindle motor having a dynamic pressure bearing according to a fifth embodiment of the present invention. FIG. 5 is a sectional view thereof.

In FIG. 5, there is provided a stator core 9 having a stator coil for generating a magnetic field in an excited state, and a rotor having a rotor magnet 10 for obtaining a rotational force by electromagnetic interaction with the magnetic field of the stator coil. The shaft 5 supporting the rotor and the sleeve 6 into which the shaft 5 is inserted are made of a conductive material. A dynamic pressure generating groove 7 is formed on the side surface of the shaft 5, and constitutes a radial bearing with the opposite sleeve 6. The thrust plate 8 is fixed to the sleeve 6 and forms a thrust bearing by making point contact with the spherical surface of the shaft end facing the thrust plate 8. Lubricating oil 4 is filled inside the bearings constituting the radial bearing and the thrust bearing, and the lubricating oil 4 contains a large number of fine particles 1 that are smaller than the gap R between the shaft 5 and the sleeve 6 and are a conductive material. . The sleeve 6 supports a hub 11 made of a conductive material, and a magnetic disk 12 is mounted on the hub 11. Reading and writing to the magnetic disk 12 is performed by a recording / reproducing head 13, and the shaft 5 is installed in a housing 14 of the magnetic disk drive. The housing 14 is a conductive material, and aluminum is often used.

When the fine particles 1 are contained in the lubricating oil 4 as described above, first, when the motor is turned on and off, the shaft 5
And the number of times the sleeve 6 slides in direct contact is reduced.
That is, since the fine particles 1 are interposed between the shaft 5 and the sleeve 6, the fine particles 1 come into contact with the shaft 5, and the fine particles 1 come into contact with the sleeve 6. Since the fine particles 1 circulate inside the bearing, the fine particles 1 interposed at the time of contact between the shaft 5 and the sleeve 6 are always replaced. In addition, the contact point is also adapted to the circulating movement of the fine particles 1, and the sliding trajectory between the surface of the shaft 5 and the inner peripheral surface of the sleeve 6 is not always the same, so that the wear resistance of the bearing portion can be improved. Further, the fine particles 1 interposed between the shaft 5 and the sleeve 6 at the time of the contact make the heat generated at the subsequent contact the lubricating oil 4.
It is possible to cool the entire surface of the lubricating oil, and it is possible to prevent thermal deterioration of the lubricating oil 4 by suppressing a rise in the temperature of the sliding portion.

Second, the shock resistance of the motor can be improved. That is, when the impact is applied to the motor, the shaft 5
Since the collision of the shaft 5 with the sleeve 6 can be prevented when the fine particles 1 are interposed between the shaft 6 and the sleeve 6, it is possible to prevent the occurrence of scratches such as dents inside the bearing, and to avoid locking of the bearing portion. Can be.

Third, discharge breakdown of the recording / reproducing head can be prevented. That is, when the rotor of the motor is charged with static electricity due to the conductive material of the fine particles 1, the shaft 5 and the sleeve 6, the static electricity can be discharged from the sleeve 6 to the shaft 5 and the housing 14 via the fine particles 1. This makes it possible to prevent the recording / reproducing head 13 from being destroyed by discharge due to static electricity.

Therefore, the number of times the shaft 5 contacts and slides on the sleeve 6 can be reduced to improve the abrasion resistance of the bearing portion and to prevent the lubricating oil 4 from being thermally degraded. Problems such as rotation unevenness, shaft inclination and shaft runout can be prevented, and the life of the bearing can be extended. Also, while improving the shock resistance of the motor,
When the rotor is charged with static electricity, it can be discharged quickly, so that the recording / reproducing head 13 can be prevented from being destroyed due to static electricity.

In this embodiment, the dynamic pressure generating groove 7 is formed on the side surface of the shaft. However, the same applies to the case where the dynamic pressure generating groove 7 is formed on the inner peripheral surface of the sleeve facing the shaft side surface. The effect is obtained. Further, a thrust bearing is formed by the point contact between the spherical surface of the shaft end face and the thrust plate 8, but the shaft end face is flat and the thrust plate 8 is formed.
The same effect can be obtained even in the case of a thrust bearing of the type in which a dynamic pressure generating groove is formed and floated.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and various applications and developments are possible within the scope of the present invention.

[0052]

As described above, the hydrodynamic bearing according to the present invention has the following effects by containing the fine particles 1, the linear member 2, or the helical linear member 3 in the lubricating oil 4.

First, by reducing the number of times of sliding of the shaft 5 and the sleeve 6 when the motor is turned on and off, the wear resistance of the bearing portion can be improved and the life can be extended. That is, the shaft 5 and the sleeve 6
The fine particle 1 or the linear member 2 or the spiral linear member 3 is interposed between the shaft 5 and the sleeve 6.
The number of times of contact sliding can be reduced. Since the fine particles 1 or the linear member 2 or the helical linear member 3 circulates inside the bearing, the sliding trajectory between the surface of the shaft 5 and the inner peripheral surface of the sleeve 6 is not always the same but changes in accordance with the circulation. Therefore, the load accumulated in the sliding portion is reduced, and the wear resistance of the bearing portion can be improved.
Further, the fine particles 1 or the linear member 2 or the spiral linear member 3 interposed between the shaft 5 and the sleeve 6 at the time of contact.
Can cool the heat generated by the contact after that using the entire surface in the lubricating oil 4, and can prevent the thermal deterioration of the lubricating oil 4 by suppressing the temperature rise of the sliding portion. In addition, the life of the bearing can be extended.

Second, it is possible to improve the shock resistance of the motor. In other words, if the particles 1 or the linear member 2 or the helical linear member 3 is interposed between the shaft 5 and the sleeve 6 when an impact is applied to the motor, the collision between the shaft 5 and the sleeve 6 is prevented, and the impact on the inside of the bearing is prevented. It is possible to prevent the occurrence of scratches such as marks, and it is possible to avoid locking of the bearing portion.

Third, discharge breakdown of the recording / reproducing head 13 can be prevented. That is, when the rotor of the motor is charged with static electricity because the fine particle 1, the linear member 2, the spiral linear member 3, the shaft 5, and the sleeve 6 are conductive materials, the fine particle 1, the linear member 2 Alternatively, the shaft 5 and the housing 14 are interposed via the spiral linear member 3.
This makes it possible to discharge static electricity, thereby preventing discharge breakdown of the recording / reproducing head 13 due to static electricity.

Therefore, the number of times the shaft 5 contacts and slides on the sleeve 6 can be reduced to improve the wear resistance of the bearing portion and prevent the lubricating oil 4 from being thermally degraded. Problems such as rotation unevenness, shaft inclination and shaft runout can be prevented, and the life of the bearing can be extended. Also, while improving the shock resistance of the motor,
When the rotor is charged with static electricity, it can be discharged quickly, so that the recording / reproducing head 13 can be prevented from being destroyed by static electricity.

Further, since such a dynamic pressure bearing is mounted, there are no problems such as uneven rotation, insufficient flying height, shaft inclination and shaft runout, and discharge breakdown of the recording / reproducing head 13 mounted on the magnetic disk drive. And realizes an excellent spindle motor having high impact resistance and a long service life.

[Brief description of the drawings]

FIG. 1 is a sectional view of a dynamic pressure bearing according to the present invention.

FIG. 2 is a sectional view of a dynamic pressure bearing according to the present invention.

FIG. 3 is a sectional view of a dynamic pressure bearing according to the present invention.

FIG. 4 is a cross-sectional view of a spindle motor equipped with a dynamic pressure bearing according to the present invention.

FIG. 5 is a cross-sectional view of a spindle motor equipped with a dynamic pressure bearing according to the present invention.

FIG. 6 is a sectional view of a conventional dynamic pressure bearing.

FIG. 7 is a sectional view of a spindle motor equipped with a conventional dynamic pressure bearing.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fine particle 2 Linear member 3 Spiral linear member 4 Lubricating oil 5 Shaft 6 Sleeve 7 Dynamic pressure generating groove 8 Thrust plate 9 Stator core 10 Rotor magnet 11 Hub 12 Magnetic disk 13 Recording / reproducing head 14 Housing 15 Thrust bearing

Claims (7)

[Claims] 1. A dynamic pressure bearing having a sleeve fitted with a shaft supporting a load in a radial direction, a thrust plate supporting a load in a thrust direction, and between the sleeve, the shaft and the thrust plate. The sleeve and the shaft are filled with a lubricant and a clearance R
Wherein the lubricating oil contains fine particles smaller than the gap R. 2. The dynamic pressure bearing according to claim 1, wherein the shaft, the sleeve, and the fine particles are made of a conductive material. 3. A dynamic pressure bearing includes a sleeve fitted with a shaft supporting a load in a radial direction, a thrust plate supporting a load in a thrust direction, and a thrust plate between the sleeve, the shaft and the thrust plate. The sleeve and the shaft are filled with a lubricant and a clearance R
Wherein the lubricating oil contains a linear member having a maximum dimension smaller than the gap R and bent into an arbitrary shape. 4. The dynamic pressure bearing according to claim 3, wherein the shaft, the sleeve, and the linear member bent in an arbitrary shape are made of a conductive material. 5. A dynamic pressure bearing having a sleeve fitted with a shaft for supporting a load in a radial direction, a thrust plate for supporting a load in a thrust direction, and between the sleeve, the shaft and the thrust plate. The sleeve and the shaft are filled with a lubricant and a clearance R
Wherein the lubricating oil contains a linear member whose maximum dimension is smaller than the gap R and is spirally bent. 6. The dynamic pressure bearing according to claim 5, wherein the shaft, the sleeve and the linear member bent in a spiral shape are made of a conductive material. 7. A rotor having a stator core having a stator coil for generating a magnetic field in an excited state, and a rotor having a rotor magnet for obtaining a rotational force by an electromagnetic interaction with the magnetic field of the stator coil. 2. A supporting shaft and sleeve, and a thrust plate.
7. A spindle motor equipped with the dynamic pressure bearing according to any one of items 1 to 6.