JP2002070843A - Bearing mechanism, driving motor with bearing mechanism and hard disc drive mechanism with driving motor and polygon miller driving mechanism - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a bearing mechanism in which reduction of manufacturing cost is attained by simplification of a bearing construction, stable bearing capacity for rotatable body is obtained even under low speed rotational state, and contact.wear between a shaft body and a bearing body in dynamic pressure bearing part is hard to occur. SOLUTION: The bearing mechanism 1 comprises: a radial dynamic pressure bearing part 20 which generates a radial dynamic pressure in a bearing clearance G by relatively rotating a first member 2 (stationary shaft) and a second member 3 (sleeve) faced each other across the bearing clearance G; a thrust base part 15 integrated with the second member 3 and facing with one end face of the first member 2; and a frictional thrust bearing part 30 which supports a thrust force generated with the relative rotation between the first member 2 and the second member 3. The contact.wear between the first member and the second member of the radial dynamic pressure bearing part becomes hard to occur between the frictional thrust bearing part securely takes up and supports the thrust force generated with the relative rotation between the first member and the second member, even under the low speed rotational state when the bearing capacity for rotatable body is easy to become unstable due to insufficiency of the radial dynamic pressure.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bearing mechanism, a drive motor using the bearing mechanism, a hard disk drive mechanism using the drive motor, and a polygon mirror drive mechanism.

[0002]

2. Description of the Related Art Conventionally, in a bearing mechanism used for a hard disk drive mechanism of a storage device or a polygon mirror drive mechanism of a copier or a laser printer, etc., a dynamic pressure bearing has been used in order to realize rotation with less whirling. May be adopted. As such a dynamic pressure bearing, for example, as disclosed in Japanese Patent Application Laid-Open No. 5-215128, a rotating shaft is inserted inside a cylindrical bearing body and, for example, an outer peripheral surface of the rotating shaft is There is known a herringbone-shaped dynamic pressure generating groove formed in a circumferential direction. In this structure, when the rotating shaft is rotated at a high speed inside the bearing body, a radial dynamic pressure is generated in a gap between the rotating shaft and the bearing body due to a pumping action of the working fluid into the dynamic pressure generating groove, for example, vibration and other When a radial force acts on the rotation axis due to a disturbance, the dynamic pressure acts as a restoring force, so that stable rotation with little whirling can be realized.

[0003]

However, in the bearing mechanism disclosed in the above-mentioned publications and the like, apart from the above-mentioned radial dynamic pressure generating grooves, a flat bearing having a thrust receiving surface substantially orthogonal to the rotation axis is provided. For example, a spiral dynamic pressure generating groove is formed in the body. As a result, thrust dynamic pressure is generated in the gap between the end face of the rotating shaft and the thrust receiving surface, and functions to receive the thrust force acting in the direction of the rotating axis, but the bearing structure is complicated, and the cost of each component is high. Since precision is required, there is a problem that manufacturing cost is increased. Furthermore, since the rotating shaft is supported by the dynamic pressure generated by the rotation of the rotating shaft in both the radial direction and the thrust direction, sufficient radial and thrust dynamic pressure is required unless the high-speed rotation of 10,000 to 20,000 rotations per minute is normally performed. In a low-speed rotation state such as when the rotation mechanism starts or stops, the support force of the rotating shaft tends to become unstable due to insufficient dynamic pressure, and the rotating shaft and the bearing body in each dynamic pressure bearing part come into contact, Wear is more likely to occur. A dynamic pressure bearing that generates radial and thrust dynamic pressure in the form of air pressure without using lubricating oil as a working fluid has also been proposed.
In the case of using air pressure, according to the study of the present inventors, it is necessary to generate a sufficient radial and thrust dynamic pressure at a higher speed of 40,000 to 50,000 revolutions per minute or more, which further promotes the above problem. It takes shape.

[0004] It is an object of the present invention to simplify the bearing structure to reduce the manufacturing cost, to obtain a stable supporting force of the rotating body even when the rotating mechanism is rotating at a low speed, and to realize the shaft and the bearing in the dynamic pressure bearing portion. An object of the present invention is to provide a bearing mechanism that is less likely to cause contact, wear, and the like with a body, a drive motor using the bearing mechanism, and a hard disk drive mechanism and a polygon mirror drive mechanism using the drive motor.

[0005]

In order to solve the above-mentioned problems, a bearing mechanism according to the present invention has a shaft-shaped first member and an insertion hole through which the first member is inserted. A predetermined amount of bearing filled with working fluid between an inner surface of the insertion hole and an outer peripheral surface of the first member in a state where relative rotation of the first member around the axis in the insertion hole is allowed; A second member forming a gap, by radially rotating the first member and the second member, to generate a radial dynamic pressure in the bearing gap, a radial dynamic pressure bearing portion, the second member and An integrated thrust base portion facing one end surface of the first member, provided between the thrust base portion and the first member, for relative rotation between the first member and the second member. Friction thrust bearing that supports the accompanying thrust force Characterized by comprising and.

A bearing mechanism according to the present invention includes a radial dynamic pressure bearing portion for generating a radial dynamic pressure around the first member by relatively rotating a first member and a second member opposed to each other with a bearing gap therebetween. A thrust base portion integrated with the second member and facing one end surface of the first member, provided between the thrust base portion and the first member, for relative rotation between the first member and the second member. And a friction thrust bearing portion for supporting the thrust force generated accordingly. As described above, by forming the friction thrust bearing portion with, for example, a metal bearing that can contact the end surface of the first member, the bearing structure can be simplified and the manufacturing cost can be reduced. Further, even in a low-speed rotation state in which the supporting force of the rotating body (the first member and / or the second member) is likely to be unstable due to insufficient radial dynamic pressure, the friction thrust bearing portion can move relative to the first member and the second member. Since the thrust force generated by the rotation is reliably received and supported, the contact between the first member and the second member in the radial dynamic pressure bearing portion
Wear is less likely to occur.

[0007] Such a friction thrust bearing portion is provided, for example, on a first member side contact member disposed on one end surface of the first member and on a shaft center portion of the thrust base portion, and is provided with a first member side contact member. And a thrust base portion side contact body that can be contacted. In this case, the first member-side contact body is fixed inside a concave portion formed on one end surface of the first member so that the outer surface is located inside the one end surface of the first member. The thrust base portion side contact body can be fixed to the thrust base portion in a form in which the axial center portion protrudes toward the first member side contact body. In this way, the first member-side contact body is positioned inside one end face of the first member, and the axial center of the thrust base portion-side contact body is formed so as to protrude toward the first member-side contact body. In addition, the size (height) in the axial direction can be reduced, and the bearing mechanism can be reduced in size and size. In addition, the recessed space formed on one end surface of the first member in this manner can be used as a lubricating oil reservoir for a friction thrust bearing portion formed of, for example, a metal bearing.

Further, one of the first member side contact body and the thrust base portion side contact body is a fixed side contact body and the other is a rotation side contact body, and the contact surface of the rotation side contact body is a fixed side contact body. By forming a curved surface protruding toward the surface, it is possible to reduce wear and the like of the contact surface of the fixed contact body due to rotation of the rotating contact body. Moreover, for example, even if there is an imbalance in the rotating body (the first member or the second member) or disturbance such as external force or vibration occurs in the radial direction, whirling may occur in the rotating body. In addition, the curved contact surface of the rotating contact body protruding toward the fixed contact body generates a restoring force to a neutral state, and stable rotation with little whirling can be realized. Therefore, contact and wear between the first member and the second member in the radial dynamic pressure bearing portion are more unlikely to occur. If the contact surface of the fixed contact body is also formed into a curved surface that is inwardly (inwardly concave) toward the center of the axis, the restoration of the rotating body to the neutral state becomes quicker and more reliable.

Here, by setting the hardness of the contact portion of the rotating contact body to be larger than the hardness of the contact portion of the fixed contact body,
A sufficient strength can be imparted to the contact portion of the rotating contact body that is easily affected by an impact when the rotating mechanism is started or stopped. In addition, by forming the contact surface of the rotating contact body having high hardness into a curved shape protruding toward the fixed contact body, the contact surface of the rotating contact body cuts into the contact surface of the fixed contact body or is cut off. Damage to the surface can be prevented. In order to provide a hardness difference, a method of integrally molding the rotating side member and the fixed side member with a material such as metal or plastic having a difference in hardness, after molding both with materials having substantially the same hardness, plating, quenching, Various methods such as a method of providing a hardness difference between both contact portions by means such as carburizing and nitriding can be adopted.

When both contact portions are made of a metal material, the hardness of the contact portion of the rotating contact member is 50-60 HRC in Rockwell hardness, and that of the fixed contact member is 5 to 60 HRC.
It is desirable to adjust to 0 to 80 HRB. When the value is below these lower limits, there is a risk of cracking or cutting due to insufficient hardness. On the other hand, when the value exceeds the upper limit, the cost as a friction bearing member may increase. In addition, Rockwell hardness HRC, HRB means what was measured by the method prescribed | regulated to JISZ224-1998.

Specifically, a steel material for a die casting die (contact portion hardness of 50 to 60 HR)
C) Bronze (contact part hardness 70)
80HRB) or sintered oil-impregnated metal (contact part hardness 50-7)
0HRB) is recommended.

As the steel material for a die-casting die, for example, the following can be used (the composition is expressed by weight%).・ Alloy tool steel D4 class (SKD4: C0.25-0.35
%, Si 0.40% or less, Mn 0.6% or less, Cr2.
00 to 3.00%, V 0.30 to 0.50%, W 5.0
0 to 6.00%, residual Fe) ・ Chromium molybdenum steel class 3 (SCM3: C0.33 ~)
0.38%, Si 0.15 to 0.35%, Mn 0.60
0.85%, Cr 0.90 to 1.20%, Mo0.1
5 to 0.35%, residual Fe) ・ Carbon tool steel type 2 (SK2: C 1.10 to 1.30%,
Si 0.35% or less, Mn 0.50% or less, residual Fe)

As the bronze, for example, the following can be used (the composition is expressed by weight%).・ Three kinds of phosphor bronze (C5212: Sn 7.0 to 9.0%,
P0.03 to 0.35%, Cu + Sn + P99.5%)-Class 1 aluminum bronze (C6161: 83.0 to 90. Cu).
0%, Fe 2.0 to 4.0%, Al 7.0 to 10.0
%, Mn 0.50 to 2.0%, Ni 0.50 to 2.0
%, Cu + Al + Fe + Ni + Mn 99.5% or more)

Further, as the sintered oil-containing metal, for example, the following can be used (the composition is represented by% by weight).・ SBF3 type 1 (SBF3118: C0.2-0.5
%, Other 3% or less, residual Fe) SBK2 type 1 (SBK2118: Fe1% or less, C
2% or less, Sn 6 to 10%, Pb 5% or less, Zn 1% or less, other 0.5% or less, residual Cu)

According to another aspect of the present invention, there is provided a drive motor including the above-described bearing mechanism, wherein one of the first member and the second member of the bearing mechanism is provided with a stator. The rotor is disposed on the other rotating side member.

According to such a drive motor, stable rotation with little whirling can be realized from low-speed rotation to high-speed rotation, and it can be adapted to a wide range of rotational load.

In a drive motor using such a bearing mechanism, in order to increase the load capacity of the dynamic pressure bearing portion, the bearing inner diameter (inner diameter of the bearing member) or the bearing length (bearing member) of the dynamic pressure bearing portion is increased. It is most effective to increase the bearing area by increasing the length of the bearing. However, on the other hand, it is not easy to increase the bearing area of the dynamic pressure bearing portion because the demand for downsizing of the motor is strong. Therefore, for example, by arranging the stator portion and the rotor portion on the opposite side of the radial thrust bearing portion in the axial direction with respect to the radial thrust bearing portion, a space portion is formed radially outside the radial dynamic pressure bearing portion. You. By doing so, the bearing inner diameter (diameter of the insertion hole of the second member) can be increased, and the bearing area of the radial dynamic pressure bearing portion can be increased. As a result, the load capacity of the radial dynamic pressure bearing portion can be increased. Can be.

When the stator portion and the rotor portion are arranged so as not to overlap in the axial direction with the bearing gap of the radial dynamic pressure bearing portion, the radially outer space of the radial dynamic pressure bearing portion is widened. And it is formed reliably.
A hard disk, a polygon mirror, and the like, which will be described later, can be attached using the radially outer space, and the space can be used without waste.

When the stationary member is erected on a horizontal motor base and the stator and the rotor are both positioned below the bearing gap of the radial dynamic pressure bearing, the center of gravity of the drive motor moves downward. Position and the stability of the drive motor is increased. When the rotating member and the rotor are integrated via the thrust base and the fixed member and the stator are integrated via the motor base, the drive motors are further compacted. be able to.

Although the effect of the present invention is sufficiently exhibited even when the working fluid is liquid, the effect of increasing the load capacity of the radial dynamic pressure bearing portion is remarkable in gas, particularly air which is a compressive fluid. In addition, the fact that a hermetic seal required for a liquid is not required, which greatly contributes to the expansion of applications.

Next, a hard disk drive mechanism according to the present invention includes the drive motor described above, and a recording hard disk which is attached to the rotating member and rotates integrally therewith.

Further, in the polygon mirror driving mechanism of the present invention, a plurality of reflection surfaces are formed in a polyhedral shape so as to be integrated with the driving motor and the rotation side member and surround the periphery of the rotation axis. And a polygon mirror.

According to such a hard disk drive mechanism or polygon mirror drive mechanism, stable rotation with little whirling can be realized from low-speed rotation to high-speed rotation.
It can adapt to a wide range of rotating loads.

[0024]

Embodiments of the present invention will be described below with reference to embodiments shown in the drawings. (Embodiment 1) FIG. 1 shows an example of a hard disk drive mechanism using the bearing mechanism of the present invention. The hard disk drive mechanism 100 is configured to
A fixed shaft 2 (fixed side member) as a first member attached by bolts 9 in a form standing up from one side thereof, and a sleeve 3 (rotary side member) as a second member rotatably disposed outside thereof. The fixed shaft 2 and the sleeve 3 constitute a radial dynamic pressure bearing portion 20 of the bearing mechanism 1.

The outer peripheral surface 2a of the fixed shaft 2 is a cylindrical surface,
A recess 2c having a circular cross section is formed at a predetermined depth in the axial direction on the upper end surface of the fixed shaft 2. The sleeve 3 is formed in a cylindrical shape having an axial insertion hole 3a, the fixed shaft 2 is inserted through the insertion hole 3a, and the outer peripheral surface of the sleeve 3 is formed by a thrust base 1 described later.
5 is fixed to the inner peripheral surface. A bearing gap G of the radial dynamic pressure bearing portion 20 is formed between the inner peripheral surface of the insertion hole 3a and the outer peripheral surface 2a of the fixed shaft 2.
Are filled with air (ie, gas).

A skirt portion 15a to which the outer peripheral surface of the sleeve 3 is fixed on the inner peripheral surface, and one end surface (upper end surface) of the fixed shaft 2
A thrust base portion 15 having a flat zenith portion 15b opposed to the thrust base portion 15 and having a cap shape as a whole
And the axis lines are made substantially coincident with each other to cover the outside of the radial dynamic pressure bearing portion 20. The tip of the skirt portion 15a enters the upper side of the horizontal motor base portion 8 from above, and the thrust base portion 15 is covered with the motor base portion 8 as if the lid was turned down.

The thrust base portion 15 also has a function as a hub, and a friction thrust bearing portion 30 composed of a metal bearing is provided between the thrust base portion 15 and the fixed shaft 2. The friction thrust bearing 30 has a fixed contact 31 as a first member contact and a rotating contact 32 as a thrust base contact. The thrust force generated by the rotation is applied to both contact bodies 31,
It supports between 32. The disc-shaped fixed contact body 31 is
Inserted into a recess 2c formed in the end face of the fixed shaft 2,
It is fixed with an adhesive or the like so that the whole is located inside (below) the end face of the fixed shaft 2. Further, a through hole 15 c having a circular cross section is provided in the axial center of the zenith portion 15 b of the thrust base 15, and the axial center is formed in a cylindrical shape inside the through hole 15 c toward the fixed contact body 31. The protruding disk-shaped main body of the rotating contact body 32 is inserted and fixed with an adhesive or the like. In this way, the fixed contact body 31 is located inside the end face of the fixed shaft 2,
When the center of the shaft of the rotating contact body 32 is protruded toward the fixed contact body 31, the dimension (height) in the axial direction is reduced,
It becomes compact as a whole.

The rotation-side contact body 32 has a hardness of 58 HR as a whole.
C is formed of a steel material for a die-casting die, and its axial center portion protrudes in a cylindrical shape toward the fixed-side contact body 31, and a contact surface 32 a of the tip with the fixed-side contact body 31 is a curved surface convex outward. (Here, spherical shape). Due to the curved contact surface 32a of the rotating contact body 32, a restoring force to a neutral state is generated, and whirling is reduced. The fixed-side contact body 31 is entirely made of bronze having a hardness of 78 HRB, and the contact surface 31 a is formed in a planar shape. As described above, when the contact surface 32a of the rotating-side contact body 32 having a high hardness is formed in a curved shape protruding toward the fixed-side contact body 31,
Fixed side contact body 3 by contact surface 32a of rotating side contact body 32
The first contact surface 31a can be prevented from being damaged. By the way, the shaft diameter D of the cylindrical projection of the rotating side contact body 32 is 2 to 10 mm.
(For example, 3 mm), the radius R of the spherical contact surface 32a
1 is adjusted to 1 to 20 mm.

Reference numeral 15d denotes a hole diameter of 0.5 to 3 which is formed to penetrate the zenith portion 15b of the thrust base portion 15 at an angle.
mm (for example, 1 mm). Lubrication hole 15d
Are provided at a plurality of locations (two locations in the embodiment) in the circumferential direction, and are used to externally supply lubricating oil or the like for reducing friction between the contact surfaces 31a and 32a. The space of the concave portion 2c formed on the end surface of the fixed shaft 2 is used as a lubricating oil reservoir at this time.

Next, a ring-shaped stator core 11a,
A coil unit 11 comprising a plurality of coils 11b wound around the core 11a at predetermined intervals in the circumferential direction.
(Stator portion) is fixedly fitted into the motor base portion 8. The coil unit 11 protrudes into an annular space 8 a formed on the upper surface side of the motor base 8, and is axially opposite to the friction thrust bearing 30 with the radial dynamic pressure bearing 20 interposed therebetween. On the side, it is arranged below the bearing gap G.

The skirt portion 15a of the thrust base portion 15 covers the coil unit 11 in the axial direction of the fixed shaft 2, and extends in a skirt shape to a position where the tip reaches the space 8a. A plurality of data recording hard disks 6 are attached to the outer peripheral surface of the skirt 15a via spacers 6a. Further, a plurality of permanent magnets 12 (rotor portions) are mounted at predetermined intervals in the circumferential direction on the inner peripheral surface side in the space 8a at a position facing the coil unit 11. These permanent magnets 12 together with the coil unit 11 constitute a drive motor 40 (drive unit), and the permanent magnets 12 connect the thrust base 15 to the sleeve 3, the hard disk 6, and the rotating contact body 32 attached thereto. It plays a role of integrally rotating and driving around the fixed shaft 2.

On the other hand, the fixed shaft 2
(And the fixed-side contact body 31) and the coil unit 11 are integrated. At this time, the coil unit 11 and the permanent magnet 12 are disposed below the radial dynamic pressure bearing portion 20 (bearing gap G), the inner diameter 2r2 of the sleeve 3 is increased, and the load capacity of the radial dynamic pressure bearing portion 20 is increased. Is increasing. The hard disk 6 is mounted in a space formed outside the radial dynamic pressure bearing portion 20 in the radial direction.

Next, assuming that the inner diameter of the insertion hole 3a is 2r2 and the outer diameter of a portion of the fixed shaft 2 inserted into the insertion hole 3a is 2r1, r2-r1 corresponding to the size of the bearing gap G is 0.1. 2
It is adjusted to 20 μm (preferably 1 to 10 μm). The inner peripheral surface of the insertion hole 3a and the outer peripheral surface 2 of the fixed shaft 2
When each cylindricity of a is C, C ≦ (r2−r1) / 2
It has been adjusted to be. However, cylindricity is JIS
The one defined in 5.4 of B0621 is adopted. The size of the bearing inner diameter, that is, 2r2, is 6 to 25 mm (for example, 1
7 mm), and the bearing gap G, that is, r2-r1 is 0.2 to 20 m (for example, 8 m). The bearing length, that is, the axial length M of the insertion hole 3a is 5 to 15 mm.
(For example, 11.8 mm). The surface roughness of the inner peripheral surface of the insertion hole 3a and the outer peripheral surface 2a of the fixed shaft 2 are each adjusted to a maximum height Ry of about 1.4 μm. However, the reference length and the evaluation length at this time are based on JIS B
The standard value in 0601-1994 is adopted.

In the hard disk drive mechanism 100 configured as described above, the coil 1 of the coil unit 11
1b to drive the drive motor 40, for example, to set the sleeve 3 at 4000 to 20000 rpm.
Rotate at the rotation speed of. Fine irregularities are dispersedly formed on the outer peripheral surface 2a of the fixed shaft 2 and the inner peripheral surface of the insertion hole 3a of the sleeve 3 facing each other with the bearing gap G interposed therebetween, and the maximum height Ry is adjusted to the above range. Therefore, a dynamic pressure is generated in the bearing gap G in the radial direction of the fixed shaft 2, that is, in the radial direction. Then, even if a radial deflection force acts on the sleeve 3 due to vibration or the like, the radial dynamic pressure serves as a restoring force, and whirling hardly occurs. In the configuration of the present embodiment, since the rotation speed for generating a sufficient radial dynamic pressure is relatively low as described above, the fixed shaft 2 and the sleeve 3
Wear is less likely to occur.

(Embodiment 2) FIG. 2 shows an example of a polygon mirror driving mechanism using the bearing mechanism of the present invention. Bearing mechanism 1 of this polygon mirror drive mechanism 200
Has a structure similar to that of the first embodiment (FIG. 1), that is, a radial dynamic pressure bearing portion 20, a thrust base portion 15, and a friction thrust bearing portion 30. Further, the drive motor 40 (drive unit) used in the polygon mirror drive mechanism 200 has the same structure as in the first embodiment. Therefore, the same reference numerals are given to the common parts with the first embodiment, and the description will be omitted.

The polygon mirror 53 has a plurality of reflection surfaces 53c formed in a polyhedral shape so as to surround the rotation axis, and is attached to the outer peripheral surface of the skirt portion 15a of the thrust base portion 15 having a function as a hub. ing. A donut-shaped magnet plate 59 is also attached to the outer peripheral surface of the skirt 15a. A plurality of permanent magnets 57 are attached to a surface of the magnet plate 59 facing the end surface on the opposite side of the polygon mirror 53 so as to surround the fixed shaft 2. This magnet 57
Gives the buoyancy by the magnetic attraction to the polygon mirror 53 to prevent the polygon mirror 53 from being bent by its own weight.

In the polygon mirror driving mechanism 200 configured as described above, the coil 1 of the coil unit 11
1b to operate the drive motor 40, for example, to move the sleeve 3 from 10,000 to 40,000 rpm.
Rotate at a rotation speed of m. Fine irregularities are dispersedly formed on the outer peripheral surface 2a of the fixed shaft 2 and the inner peripheral surface of the insertion hole 3a of the sleeve 3 opposed to each other with the bearing gap G interposed therebetween, and the maximum height Ry is adjusted to the above range. Therefore, a dynamic pressure is generated in the bearing gap G in the radial direction of the fixed shaft 2, that is, in the radial direction. This radial dynamic pressure contributes to preventing the polygon mirror 53 from whirling.

(Embodiment 3) In the bearing mechanism of the present invention, at least one of the outer peripheral surface of the first member and the inner peripheral surface of the second member opposed to the first member together with the scattered minute irregularities. Thus, a groove portion contributing to the generation of radial dynamic pressure can be formed. FIG. 3 shows an example. In this bearing mechanism 71, an outer peripheral surface 72a of a fixed shaft 72 (fixed member) as a first member and an insertion hole 7 of a sleeve 73 (rotary member) as a second member disposed outside the fixed shaft 72 (fixed member).
A bearing gap G is formed between the inner peripheral surface of the bearing 3a and the inner peripheral surface 3a. On the outer peripheral surface 72a of the fixed shaft 72, rows of grooves 72c for generating dynamic pressure are formed at a plurality of locations (two locations in this embodiment) in the axial direction. Each groove row is formed over the entire circumference at a predetermined interval so that the tip of the mountain-shaped (or boomerang-shaped) pattern of each groove 72c is positioned on a reference line BL in the circumferential direction of the fixed shaft 72. Yes (so-called herringbone form). A circumferential auxiliary groove 72d connecting one end of the groove 72c may be formed for each row. Further, the step of forming such a groove pattern can be performed before or after the step of forming minute unevenness.

(Embodiment 4) In the friction thrust bearing portion of the bearing mechanism of the present invention, in order to increase the recovery force against the whirling of the rotating body, the fixed side contact body (first member side contact body) and the rotating side contact body. The state of contact with the (thrust base portion side contact body) can be variously changed. FIG. 4A shows the first embodiment.
And the contact surface 32a of the rotating contact body 32 as in the second embodiment.
Indicates a curved surface (for example, a spherical shape having a radius R1), and the contact surface 31a of the fixed contact body 31 is formed in a horizontal plane. An imbalance exists in the rotating body (the thrust base 15, the rotating side contact body 32, the sleeve 3, the permanent magnet 12, etc.), or a disturbance such as an external force or vibration occurs in the radial direction, and the rotating body shakes. Around may occur.
At this time, if the contact surface 32a of the rotating contact body 32 is formed in a curved surface, a restoring force to a neutral state is generated, and the whirling of the rotating body is terminated.

FIGS. 4B and 4C show an example in which the contact surface 31a of the fixed contact body 31 is also curved. 4 (b) shows the case where the contact surface 31a is formed into a spherical shape with a radius R2 (where R1 <R2), and FIG. 4 (c) shows the case where the contact surface 31a is formed as an inverted conical shape which becomes lower toward the center of the axis. Is shown. In these cases, the rotating contact body 32
When the rotational axis of the rotating body deviates from the axis of the fixed contact body 31 and whirling occurs, the restoration of the rotating body to the neutral state becomes more prompt and reliable. The reason is that the fixed contact body 3
The first curved contact surface 31a acts to regulate the amount of axial deviation of the rotating contact body 32 (the amount of whirling of the rotating body), and the curved contact surface 31a moves to the neutral position of the rotating contact body 32. It is conceivable to act to suppress the excessive amount (return amount) at the time of return.

In the embodiment described above, air is used as the working fluid that fills the bearing gap G, but the present invention can be applied to other liquids such as gas and oil. Note that when the rotating contact body 32 rotates at a high speed, the contact surface 32a may float from the contact surface 31a of the fixed contact body 31 and may not come into contact therewith, but this has no effect on the essence of the present invention. Not something.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing an example of a hard disk drive mechanism employing a bearing mechanism of the present invention.

FIG. 2 is a longitudinal sectional view showing an example of a polygon mirror driving mechanism employing the bearing mechanism of the present invention.

FIG. 3 is an explanatory view showing an example in which grooves are formed along with minute irregularities on a roughened surface of a radial dynamic pressure bearing.

FIG. 4 is a schematic diagram showing a contact state between a fixed contact body and a rotating contact body.

[Explanation of symbols]

 Reference Signs List 1 bearing mechanism 2 fixed shaft (first member; fixed side member) 2a outer peripheral surface 2c concave portion 3 sleeve (second member; rotating side member) 3a insertion hole 6 hard disk 8 motor base portion 11 coil unit (stator portion) 12 permanent magnet (Rotor part) 15 Thrust base part 20 Radial dynamic pressure bearing part 30 Friction thrust bearing part 31 Fixed side contact body (First member side contact body) 31a Contact surface 32 Rotation side contact body (Thrust base part side contact body) 32a Contact Surface 40 Drive motor (drive unit) 53 Polygon mirror 71 Bearing mechanism 72 Fixed shaft (first member; fixed side member) 72a Outer peripheral surface 73 Sleeve (second member; rotating side member) 73a Insertion hole 100 Hard disk drive mechanism 200 Polygon mirror Drive mechanism G Bearing clearance

Continued on the front page F term (reference) 3J011 AA04 AA06 AA20 BA02 CA01 DA02 JA02 KA04 LA04 MA02 5H605 AA00 BB05 BB19 CC04 EB03 EB06 5H607 BB01 BB14 BB17 CC01 DD01 DD02 DD05 DD16 GG01 GG02 GG09 GG12 GG14

Claims (6)

[Claims] A first member having a shaft shape, and an insertion hole through which the first member is inserted, wherein the insertion is performed in a state in which relative rotation of the first member around the axis of the first member is allowed. A second member that forms a predetermined amount of bearing clearance filled with a working fluid between the inner surface of the hole and the outer peripheral surface of the first member,
A radial dynamic pressure bearing portion that generates radial dynamic pressure in the bearing gap by relatively rotating the first member and the second member, and one of the first member is integrated with the second member. A thrust base portion facing the end face, provided between the thrust base portion and the first member,
A bearing mechanism, comprising: a friction thrust bearing portion for supporting a thrust force generated by the relative rotation of the first member and the second member. 2. The friction thrust bearing portion is disposed at a first member side contact body disposed on one end face of the first member, and is disposed at an axial center portion of the thrust base portion, wherein the first member side contact member is disposed. A thrust base portion-side contact body capable of contacting the body, one of the first member-side contact body and the thrust base portion-side contact body being a fixed contact body, and the other being a rotating contact body. 2. The bearing mechanism according to claim 1, wherein a contact surface of the rotating contact body is formed into a curved surface protruding toward the fixed contact body. 3. 3. The hardness of the contact portion of the rotating contact body is greater than the hardness of the contact portion of the fixed contact body.
The described bearing mechanism. 4. The bearing mechanism according to claim 1, wherein one of the first member and the second member of the bearing mechanism has a stator portion and the other has a rotating side. A drive motor, wherein a rotor portion is arranged on each member. 5. A hard disk drive mechanism comprising: the drive motor according to claim 4; and a hard disk attached to the rotating member and rotating integrally therewith. 6. A drive motor according to claim 4, further comprising: a polygon mirror integrated with the rotation-side member and having a plurality of reflection surfaces formed in a polyhedral shape so as to surround a rotation axis thereof. A polygon mirror driving mechanism.