JP2004144149A - Dynamic pressure bearing device, spindle motor using this device, and disk driving device equipped with this spindle motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a dynamic pressure bearing device with high reliability and a long life span by reducing a diameter of a thrust bearing portion without deteriorating rigidity of a bearing support portion. <P>SOLUTION: In the dynamic pressure bearing device equipped with upper and lower radial dynamic pressure bearing portions 30, 32 that use air as working fluid and upper and lower thrust dynamic pressure bearing portions 34, 36 that use lubricating liquid as working fluid, since the thrust dynamic pressure bearing portion is provided with a taper seal 16 in the axial direction, the diameter of the thrust bearing portion can be reduced without reducing the diameter of a shaft 2. In addition, since oil 14 is circulated due to an oil circulating hole 38 arranged on a thrust plate 10, air bubble entering into the thrust dynamic pressure bearing portion can be discharged to outside. Due to an air communicating hole 18 arranged on the shaft 2, atmospheric pressure above and below the thrust dynamic pressure bearing portion can be uniformed. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a dynamic pressure bearing device, a spindle motor using the same, and a disk drive device provided with the spindle motor. More specifically, the present invention relates to a so-called hybrid type dynamic device using both liquid and air as working fluids for a dynamic pressure bearing. The present invention relates to a pressure bearing device, a spindle motor using the same, and a disk drive device including the spindle motor.
[0002]
[Prior art]
In a spindle motor used in a disk drive for driving a recording disk such as a hard disk, a dynamic pressure bearing has been adopted as a bearing means because of a higher rotation speed.
[0003]
Such dynamic pressure bearings are broadly divided into liquid dynamic pressure bearings using liquid as working fluid and air dynamic pressure bearings using air as working fluid. The former has the advantage of being able to respond to miniaturization and has the advantages of quietness and excellent runout accuracy.However, the lubricating liquid may leak out of the bearing during high-speed rotation. This has the disadvantage that not only the leakage of the lubricating liquid is promoted at high temperatures, but also the bearing stiffness, especially the radial stiffness, tends to change due to the change in the viscosity of the lubricating liquid.
[0004]
On the other hand, the latter bearing, which uses air as the working fluid, has the advantage that there is no need to worry about leakage of lubricating liquid, no seal mechanism is required, the structure is simple, and there is little change in rigidity over a wide temperature range. On the other hand, since the fixed-side member and the rotating-side member are supported with air interposed therebetween, electrostatic charges accumulated in the rotating-side member cannot be released to the fixed-side member, and various kinds of static electricity troubles may occur. there were. Also, with a spindle motor using an air dynamic pressure bearing, it is difficult to increase the damping constant because the working fluid is low-density air. Concerns exist. In particular, such a problem becomes remarkable when applied to a disk drive. As a result, in particular, sliding trouble in the thrust bearing portion at the time of starting / stopping is likely to occur, and bearing performance is likely to be reduced due to wear of the bearing surface.
[0005]
Therefore, a so-called composite type dynamic pressure bearing has been developed in which a liquid is used as a lubricating fluid in the thrust bearing portion and a gas is used as the lubricating fluid in the radial bearing portion. In this hybrid type dynamic pressure bearing, by combining each bearing with each lubricating fluid, the problems of the conventional hydrodynamic bearing using a single type of lubricating fluid are eliminated, and as a result, optimal performance is realized. I have. (For example, see Patent Document 1).
[0006]
[Patent Document]
US Pat. No. 6,071,014
[Problems to be solved by the invention]
In a motor using a thrust dynamic pressure bearing, when the motor rotates at a high speed, a sufficient floating amount can be obtained even if the thrust bearing portion has a small diameter. It is desirable to reduce the diameter of the thrust bearing portion in order to reduce the current value. However, if the diameter of the fastening portion of the thrust plate of the shaft is reduced, the rigidity of the bearing support portion is reduced, and NRRO (non-repetitive runout component) and vibration Problems such as an increase in response occur. Therefore, the diameter of the thrust bearing cannot be reduced, and a large torque is generated, which is an obstacle to current reduction.
[0008]
When a liquid is used as the working fluid, a higher centrifugal force acts on the liquid by the high-speed rotation. For this reason, there is a concern that the lubricating liquid flows out of the bearing during high-speed rotation, and the amount of the lubricating liquid retained in the bearing portion is reduced. If the amount of the lubricating liquid held in the bearing portion is insufficient, not only the bearing rigidity of the dynamic pressure bearing is reduced and the rotation support becomes unstable, but also the contact sliding between the rotating side member and the stationary side member is reduced. And burn-in occurs.
[0009]
Further, the inside of the disk drive, which is originally kept in a clean environment, is contaminated by the lubricating liquid flowing out of the bearing, and contaminants and particles resulting therefrom reduce the reliability of the disk drive, such as poor data reading and writing. Problems arise.
[0010]
The present invention reduces the current value without reducing the thrust plate fastening portion of the shaft and reducing the diameter of the thrust bearing portion without impairing the rigidity of the bearing support portion. An object of the present invention is to provide a pressure bearing device, a spindle motor using the same, and a disk drive device provided with the spindle motor.
[0011]
[Means for Solving the Problems]
The dynamic pressure bearing device according to claim 1, wherein the shaft, a disk-shaped thrust plate extending radially outward from an outer peripheral surface of the shaft, and the shaft and the thrust plate are provided with a minute gap. A dynamic pressure bearing device comprising: a surrounding member; and a dynamic pressure bearing that rotatably supports the shaft and the thrust plate and the surrounding member, wherein the dynamic pressure bearing uses air as a working fluid. A thrust dynamic pressure bearing portion that uses a lubricating liquid as a working fluid, and at the interface between the shaft and the thrust plate and the lubricating liquid filled in the minute gap between the surrounding member, the thrust On both sides of the plate in the axial direction, a taper in which a minute gap between the shaft and the surrounding member expands as the distance from the thrust plate in the axial direction increases. And the shaft and the surrounding member in the taper seal have a slope that inclines inward in the radial direction as the shaft and the surrounding member move away from the thrust plate in the axial direction, and the respective inclination angles of the shaft and the surrounding member Are different. Since the taper seal is provided in the axial direction, the diameter of the thrust dynamic pressure bearing can be reduced without reducing the diameter of the thrust plate fastening part of the shaft, and the current can be reduced without impairing the rigidity of the bearing support. can do. Further, since the inclination of the taper seal is such that the seal is strengthened by centrifugal force, outflow of the lubricating liquid due to centrifugal force during high-speed rotation is prevented.
[0012]
The dynamic pressure bearing device according to claim 2, wherein the shaft communicates with the vertical hole in an axial direction and a position axially outward from an interface of the lubricating liquid in the thrust dynamic pressure bearing portion. And an air communication hole constituted by a lateral hole provided in the radial direction, and the air communication hole uniformizes the air pressure on both axial sides of the thrust dynamic pressure bearing portion. Therefore, by the pumping action of the radial dynamic pressure bearing portion, the air flowing in from the gap around the upper end of the shaft increases the pressure above the upper thrust bearing portion, thereby preventing leakage of the lubricating liquid caused by the oil moving downward. Can be.
[0013]
The dynamic pressure bearing device according to claim 3, wherein the thrust plate has an axial through hole continuous with the outer peripheral surface of the shaft, and the inner surface of the thrust plate passes from the through hole to the outer peripheral surface. A lubricating liquid circulation hole is formed by the opened horizontal hole, and the lubricating liquid moves in the lubricating liquid circulation hole from the outside to the inside in the radial direction, and passes through the gap between the thrust plate and the surrounding member. Moving from the inside to the outside, the air bubbles that have entered the thrust hydrodynamic bearing can be discharged to the outside, preventing leakage of the lubricating liquid and seizure of the bearing due to the incorporation of air bubbles into the lubricating liquid. Can be prevented.
[0014]
The spindle motor according to claim 4, wherein the bracket holds a stator, a rotor hub that rotates relative to the bracket, a rotor magnet that is fixed to the rotor hub, and generates a rotating magnetic field in cooperation with the stator. A spindle motor comprising: a dynamic pressure bearing device that supports rotation of a rotor hub; wherein the dynamic pressure bearing device is the dynamic pressure bearing device according to any one of claims 1 to 3, wherein the shaft is the bracket or the bracket. Since the surrounding member is connected to the rotor hub or the bracket and connected to the rotor hub, higher rotational stability can be obtained.
[0015]
6. The disk drive according to claim 5, wherein the disk drive is provided with a disk-shaped recording medium capable of recording information, and a spindle motor for rotating the recording medium and information is written at a required position of the spindle motor. Or a disk drive device having information access means for reading, wherein the spindle motor is the spindle motor described in claim 4, and the recording medium is mounted on the rotor hub, thereby achieving high reliability and The present invention can be suitably used in a disk drive that drives a hard disk that requires durability.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of a dynamic pressure bearing device according to the present invention, a spindle motor using the same, and a disk drive device provided with the spindle motor will be described with reference to FIGS. 1 to 3. The present invention will be described below. It is not limited to the embodiment. In the description of the present embodiment, the vertical direction in each drawing is referred to as “vertical direction” for convenience, but the direction in the actual mounting state of the spindle motor is not limited.
[0017]
1 and 2, the shaft 2 extends in the axial direction, and has a large-diameter portion 2a in a region of 2/3 of the axial length excluding both end portions, and a medium-diameter portion 2b in the remaining 1/3 region. The shaft 2 is provided on the bracket 26 in an upright state by fitting a lower end of the member into a center hole 26 a of the bracket 26. A disk-shaped thrust plate 10 extending radially outward from the outer periphery is attached to the middle diameter portion 2b of the shaft 2. The bracket 26 is fixed to a base A of the disk drive by screwing or the like, and a cover member B of the disk drive is screwed to the upper end of the shaft 2.
[0018]
The surrounding member as a rotor that rotates relatively to the shaft 2 faces a cylindrical sleeve 6 that faces the large-diameter portion 2a of the shaft 2 via a small gap, and faces the lower surface of the large-diameter portion 2a. An annular thrust bush 8 facing the upper surface and the outer peripheral surface of the thrust plate 10 via a small gap, a thrust cover 12 attached to the thrust bush 8 and facing the lower surface of the thrust plate 10 via a small gap, It comprises an inverted cup-shaped rotor hub 4 that holds the sleeve 6 and the thrust bush 8 on the inner periphery and has a ceiling wall portion that covers the upper surface of the large diameter portion 2a.
[0019]
A plurality of disks 20 are mounted on the flange 4a provided on the outer peripheral surface of the rotor hub 4 between the respective disks 20 via spacers 22, and are fixed by clamp members (not shown). An annular rotor magnet 24 is attached to the outer peripheral surface of the rotor hub 4 below the flange portion 4a, and faces a stator 28 attached to the inner peripheral wall of the outer peripheral wall of the bracket 26 with a small gap in the radial direction. ing. When the coil of the stator 28 is energized to excite the coil, a rotational force is generated on the rotor magnet 24 side by electromagnetic interaction between the stator 28 and the rotor magnet 24, and the surrounding member including the rotor hub 4 is Rotate in a predetermined direction.
[0020]
The surface of the large-diameter portion 2a of the shaft 2 is formed by connecting a pair of spiral grooves inclined in a direction opposite to the rotation direction, and is formed by a substantially "<"-shaped herringbone groove 30a, 32a. The upper radial dynamic pressure bearing portion 30 and the lower radial dynamic pressure bearing portion 32 which use air as a working fluid are formed between the sleeve 6 and the sleeve 6.
[0021]
The minute gap formed by the upper end surface of the sleeve 6 and the top wall of the rotor hub 4 and the minute gap formed by the lower end surface of the sleeve 6 and the thrust bush 8 are closed on the outer peripheral side. The abrasion powder generated in the dynamic pressure bearing portions 30 and 32 and moved by centrifugal force is accommodated, and the abrasion powder is prevented from flowing out of the motor external space.
[0022]
The small gap between the thrust plate 10, the thrust bush 8 and the thrust cover 12 is filled with oil 14 as a working fluid, and the surface of the thrust bush 8 facing the upper surface of the thrust plate 10 is formed by a herringbone groove 34a. The dynamic pressure generating groove row is formed concentrically, the upper thrust dynamic pressure bearing portion 34 is formed, and the dynamic pressure generating groove row by the herringbone groove 36a is concentric on the surface of the thrust cover 12 facing the lower surface of the thrust plate 10. The lower thrust dynamic pressure bearing portion 36 is formed.
[0023]
A taper seal 16 is provided at a portion where the outer peripheral surface of the middle diameter portion 2b of the shaft 2 above and below the thrust plate 10 faces the thrust bush 8 and the thrust cover 12, respectively. The interface of the oil 14 filled in the minute gap is located on each of the taper seals 16, and leakage of the oil 14 is prevented by using surface tension.
[0024]
The two taper seals 16 are formed in the radial direction as the portion where the outer peripheral surface of the middle diameter portion 2b of the shaft 2 above and below the thrust plate 10 faces the thrust bush 8 and the thrust cover 12 is separated from the thrust plate 10 in the axial direction. It is inclined toward. The outer peripheral surface of the middle diameter portion 2b of the shaft 2 and the portion where the thrust bush 8 and the thrust cover 12 face each other have different inclination angles, and the inclination angle of the outer peripheral surface of the middle diameter portion 2b with respect to the axis of the shaft 2 Are set larger than the inclination angles of the thrust bush 8 and the thrust cover 12. When the taper seal 16 is inclined inward in the radial direction as described above, the centrifugal force acting on the oil 14 in the taper seal 16 during rotation of the rotor becomes a force for pushing the oil 14 toward the thrust plate 10, and the interface of the oil 14 Can be prevented as much as possible.
[0025]
Here, in the case of providing a taper seal in the radial direction, after the oil is injected, the thrust bush is bonded and fixed to the thrust bush, but when the oil is injected, the thrust cover is bonded and fixed to the thrust bush. The oil adheres to the adhesive application position, weakens the adhesive strength, and there is a possibility that the oil leaks therefrom. However, according to the present invention, since both taper seals 16 are provided in the axial direction, the thrust cover 12 is bonded and fixed to the thrust bush 8 and the upper and lower thrust dynamic pressure bearing portions 34 and 36 are assembled. The oil 14 can be injected from a minute gap between the cover 12 and the shaft 2. Therefore, the problem of oil leakage due to poor bonding does not occur.
[0026]
The thrust plate 10 has a through hole 38 a penetrating the thrust plate 10 in the axial direction, and a lateral hole that passes through the thrust plate 10 radially outward from the through hole 38 a and opens to the outer peripheral surface of the thrust plate 10. An oil circulation hole 38 is formed with the hole 38b. The thrust plate 10 is provided with at least one oil circulation hole 38. In the specific example shown in the figure, a notch groove in the axial direction is formed on the inner peripheral surface of the thrust plate 10, and a through hole 38a is formed with the outer peripheral surface of the middle diameter portion 12b.
[0027]
When the surrounding member rotates with respect to the shaft 2, the pressure of the oil 14 increases in each of the upper and lower thrust dynamic pressure bearing portions 34 and 36 to generate a floating force to support the thrust. Due to the action, a part of the oil 14 moves radially outward in the minute gap between the upper surface of the thrust plate 10 and the thrust bush 8 and the minute gap between the lower surface of the thrust plate 10 and the thrust cover 12, respectively. Then, the oil 14 is circulated from the opening of the horizontal hole 38b of the thrust plate to the inside of the horizontal hole 38b from the outside in the radial direction to the inside, and further to the axial direction of the through hole 38a.
[0028]
Air bubbles may be generated in the oil 14 when the oil 14 is injected or when air is entrained by vibration or inclination during rotation of the motor. In such a case, with the rotation of the rotor hub 4, a band-shaped air layer is formed around the thrust plate 10, and the band-shaped air layer and the herringbone grooves 34a, 36a come into contact with each other to generate vibration. There is a problem that the NRRO deteriorates or the air thermally expands due to a rise in temperature, and the oil 14 is pushed out of the upper and lower thrust dynamic pressure bearing portions 34 and 36 and scattered. However, as described above, the air bubbles generated around the thrust plate 10 move together with the oil 14 through the oil circulation holes 38 and are discharged from the oil interface to the outside of the upper and lower thrust dynamic pressure bearings 34, 36. Thus, the above problem can be solved.
[0029]
The shaft 2 has a longitudinal hole 18a penetrating at least through the middle diameter portion 2b in the axial direction from the lower end, and a radially inward direction communicating with the longitudinal hole 18a from a position away from the oil interface of the taper seal 16. An air communication hole 18 constituted by a lateral hole 18b provided to the front is provided. The opening of the lateral hole 18b on the outer peripheral surface of the middle diameter portion 2b of the shaft 2 is at least one lower position above the oil interface and at a position facing the minute gap between the thrust bush 8 and the lower surface of the shaft large diameter portion 2a. At least one portion is provided below the oil interface at a position facing the gap between the thrust cover 12 and the bracket 26. After the shaft 2 is completely processed and washed, the vertical hole 18a is sealed at the lower end opening thereof with a sealing member 18c made of an elastic member such as rubber.
[0030]
The lower end of the lower radial dynamic pressure bearing portion 32 communicates with the air communication hole 18 formed in the shaft 2 and communicates with the outer space of the motor, and the upper end of the upper radial dynamic pressure bearing portion 30 connects with the top wall of the rotor hub 4. Through the motor outside space. Accordingly, the gas in the upper and lower radial dynamic pressure bearing portions 30 and 32 flows to the motor external space without mixing with the oil 14 in the upper and lower thrust dynamic pressure bearing portions 34 and 36, and the upper and lower radial dynamic A partial negative pressure region is not formed in the pressure bearing portions 30 and 32. In the case of a hydrodynamic bearing using gas as a lubricating fluid, if a pressure distribution including a negative pressure region smaller than the atmospheric pressure is formed in a minute gap, it may cause deterioration of bearing characteristics. It is desirable that the negative pressure region is not formed as much as possible. Therefore, in the present invention, the upper and lower radial dynamic pressure bearing portions 30 and 32 are communicated with a motor external space that is substantially equal to the atmospheric pressure.
[0031]
The herringbone grooves 30a and 32a of the upper and lower radial dynamic pressure bearing portions 30 and 32 lose their symmetry and become asymmetric even if only at the intersection in processing, which may cause a negative pressure region. The negative pressure can be eliminated by the air communication hole 18.
[0032]
The air communication holes 18 provided in the shaft 2 make it possible to equalize the air pressure above and below the upper and lower thrust dynamic pressure bearing portions 34 and 36. Therefore, the pressure above the upper thrust bearing portion 34 is increased by the air flowing from the gap around the upper end of the shaft 2 due to the pumping action of the upper radial dynamic pressure bearing portion 30, and the oil 14 moves downward, thereby causing oil leakage. The problem of causing can be prevented.
[0033]
FIG. 3 is a schematic diagram showing the internal configuration of a general disk drive device 40. The interior of the housing 42 including the base A and the cover member B forms a clean space with extremely little dust and dirt, and a spindle motor 44 is installed in the interior. A disk 20 for storing information is mounted on the rotor hub of the spindle motor 44. In addition, a head moving mechanism 46 for reading and writing information from and to the disk 20 is disposed inside the housing 42. The head moving mechanism 46 includes a head 48 for reading and writing information on the disk 20, and an arm for supporting the head 48. The actuator unit 52 moves the head 50, the head 48, and the arm 50 to required positions on the disk 20.
[0034]
By using the spindle motor shown in FIGS. 1 and 2 as the spindle motor of such a disk drive, a disk drive having excellent reliability and durability can be provided.
[0035]
The embodiments of the hydrodynamic bearing device according to the present invention, the spindle motor using the same, and the disk drive device provided with the spindle motor have been described. However, the present invention is not limited to such an embodiment. Various changes and modifications are possible without departing from the scope of the present invention.
[0036]
For example, the bracket 26 is fixed to a housing (shown as a housing 42 in FIG. 3) of a disk drive device by means of screws or the like. By integrating the housing 42 and the bracket 26, the housing 42 is It is also possible to use as.
[0037]
In the radial dynamic pressure bearing portion, herringbone grooves 30a and 32a provided in the large diameter portion 2a of the shaft 2 are provided on the inner peripheral surface of the sleeve 6, or the large diameter portion 2a of the shaft 2 and the sleeve 6 It is also possible to provide on both of the inner peripheral surfaces. In the thrust dynamic pressure bearing portion, the herringbone grooves 34a, 36a provided in the thrust bush 8 and the thrust cover 12 are provided on the upper surface and the lower surface of the thrust plate 10, or the upper and lower surfaces of the thrust plate 10 and the thrust opposed thereto are provided. It is also possible to provide both on the bush 8 and the thrust cover 12.
[0038]
The spindle motor according to the present invention can be employed not only in a hard disk recording device but also in other recording disk driving devices, polygon mirror driving devices of laser beam printers, color wheel driving devices used in projectors, and the like.
[0039]
【The invention's effect】
In the hydrodynamic bearing device according to claim 1, since the upper and lower thrust dynamic pressure bearing portions are provided with taper seals in the axial direction, the upper and lower thrust thrust bearings are provided in comparison with the case where the taper seals are provided in the radial direction. The diameter of the dynamic pressure bearing can be reduced. The diameter of the thrust dynamic pressure bearing can be reduced without reducing the diameter of the thrust plate fastening part of the shaft, so that the torque can be reduced without lowering the rigidity of the bearing support, and the current can be reduced. Can be expected. Further, since the inclination of the taper seal is such that the seal is strengthened by centrifugal force, outflow of the lubricating liquid due to centrifugal force during high-speed rotation is prevented.
[0040]
In addition, in the case of a thrust dynamic pressure bearing provided with a taper seal in the radial direction, since the thrust cover must be bonded to the thrust bush after oil injection due to its structure, there is a high risk of oil adhering to the adhesive application position, Oil leakage occurs due to defective adhesive. However, according to the present invention, since the taper seal for preventing oil leakage is provided in the axial direction, oil can be injected from the gap between the shaft and the thrust cover after the thrust dynamic pressure bearing is assembled, so that the oil adheres to the bonding surface. Thus, oil leakage due to poor adhesion can be prevented.
[0041]
In the dynamic pressure bearing device according to the second aspect, the provision of the air communication hole can prevent the partial negative pressure region from being generated in the radial dynamic pressure bearing portion, so that the bearing characteristics are deteriorated due to the negative pressure region. Can be prevented. Also, since the air pressure above and below the thrust dynamic pressure bearing can be made uniform, the pumping action of the radial dynamic pressure bearing causes a high pressure above the upper thrust bearing due to the air flowing in from the gap around the upper end of the shaft. It is possible to prevent the problem that oil moves downward and causes oil leakage.
[0042]
In the dynamic pressure bearing according to the third aspect, bubbles may be generated in the oil in the upper and lower thrust dynamic pressure bearing portions by entraining air due to vibration or inclination during oil injection or rotation of the motor. However, since the oil in the upper and lower thrust dynamic pressure bearings is circulated by the oil circulation holes provided in the thrust plate, the air bubbles that have entered the upper and lower thrust dynamic pressure bearings can be discharged to the outside. Therefore, it is possible to prevent problems such as oil leakage due to air bubbles entering the oil, seizure of the bearing, deterioration of the NRRO, and thermal expansion of the air due to temperature rise, which pushes the oil out of the bearing and scatters.
[0043]
A spindle motor according to a fourth aspect includes the hydrodynamic bearing device according to any one of the first to third aspects, wherein the shaft is connected to a bracket or a rotor hub, and the surrounding member is connected to the rotor hub or the bracket. As a result, higher rotational stability can be obtained.
[0044]
Since the disk drive device according to the fifth aspect has the spindle motor according to the fourth aspect, the disk drive device is excellent in reliability and durability.
[Brief description of the drawings]
FIG. 1 is a sectional view of a spindle motor according to an embodiment of the present invention.
FIG. 2 is an enlarged sectional view of a main part of the spindle motor according to the embodiment of the present invention.
FIG. 3 is a cross-sectional view schematically showing an internal configuration of the disk drive device.
[Explanation of symbols]
2 Shaft 4 Rotor hub 6 Sleeve 8 Thrust bush 10 Thrust plate 12 Thrust cover 14 Oil 16 Taper seal 18 Air communication hole 18a Vertical hole 18b Horizontal hole 20 Disk 24 Rotor magnet 26 Bracket 28 Stator 30 Upper radial dynamic pressure bearing 32 Lower radial movement Pressure bearing part 34 Upper thrust dynamic pressure bearing part 36 Lower thrust dynamic pressure bearing part 38 Oil circulation hole 38a Through hole 38b Horizontal hole 40 Disk drive device 44 Spindle motor 48 Head

Claims (5)

A shaft, a disk-shaped thrust plate extending radially outward from an outer peripheral surface of the shaft, a surrounding member having a minute gap and surrounding the shaft and the thrust plate, the shaft and the thrust plate, A dynamic pressure bearing device comprising: a dynamic pressure bearing that rotatably supports the surrounding member.
The dynamic pressure bearing includes a radial dynamic pressure bearing portion using air as a working fluid, and a thrust dynamic pressure bearing portion using a lubricating liquid as a working fluid,
At the interface portion of the lubricating liquid filled in the minute gap between the shaft and the thrust plate and the surrounding member,
On both sides of the thrust plate in the axial direction, tapered seals are provided in which a minute gap between the shaft and the surrounding member expands as the distance from the thrust plate in the axial direction increases, and the shaft and the surrounding member in the tapered seal are provided. A hydrodynamic bearing device characterized in that it has a slope that inclines radially inward as it moves further away from the thrust plate in the axial direction, and the shaft and the surrounding member have different inclination angles. The shaft comprises a vertical hole in the axial direction and a horizontal hole provided in the radial direction so as to communicate with the vertical hole from a position axially outward from the interface of the lubricating liquid in the thrust dynamic pressure bearing portion. The dynamic pressure bearing device according to claim 1, further comprising an air communication hole provided, wherein the air communication hole makes uniform the air pressure on both axial sides of the thrust dynamic pressure bearing portion. In the thrust plate, a lubricating liquid circulation hole is formed by an axial through hole continuous to the outer peripheral surface of the shaft, and a lateral hole opened from the through hole to the outer peripheral surface through the inside of the thrust plate. The lubricating liquid moves in the lubricating liquid circulation hole inward from the radially outward direction and moves from the radially inward to outward direction in the gap between the thrust plate and the surrounding member. The dynamic pressure bearing device according to claim 1, wherein: A bracket that holds the stator, a rotor hub that rotates relative to the bracket, a rotor magnet that is fixed to the rotor hub and generates a rotating magnetic field in cooperation with the stator, and a hydrodynamic bearing device that supports rotation of the rotor hub In a spindle motor having
The dynamic pressure bearing device according to any one of claims 1 to 3, wherein the shaft is connected to the bracket or the rotor hub, and the surrounding member is connected to the rotor hub or the bracket. A spindle motor. A disk drive device on which a disk-shaped recording medium capable of recording information is mounted, comprising: a disk having a spindle motor for rotating the recording medium; and information access means for writing or reading information at a required position of the spindle motor. A drive device,
5. The disk drive device according to claim 4, wherein the spindle motor is the spindle motor according to claim 4, wherein the recording medium is mounted on the rotor hub.

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