JP3551036B2 - Spindle device with hydrodynamic bearing - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a spindle device mounted on, for example, a disk drive for rotating a disk. In particular, the present invention relates to a structure of an outer rotor type spindle motor in which a rotor magnet is fixed to an inner diameter portion of a hub on which a magnetic disk is mounted in a magnetic disk drive device.
[0002]
[Prior art]
2. Description of the Related Art In recent years, there has been a remarkable tendency to increase the capacity of computer systems due to the spread of computer networks, the spread of engineering workstations, and the utilization of databases. In addition, the mainstream of magnetic disk drive devices used as storage devices of computer systems has moved from 5 inches to 3.5 inches, and the size and thickness of the devices have been reduced. Along with the demand for such a magnetic disk drive device having a large capacity, a small size, and a low thickness, a spindle device, that is, a spindle motor (hereinafter, simply referred to as a motor) mounted on the device is also required to have high accuracy. Miniaturization is required. Particularly, the demand for higher precision is extremely strong.
[0003]
With the development of technology, the storage capacity of magnetic disk drive devices has also increased. Currently, magnetic disks mounted on such devices are capable of 8000 TPI (tracks / inch) to 10000 TPI, and have a fine spacing of about 3 μm in terms of track pitch. become. The performance required of the motor mounted on the apparatus is to always accurately trace each track at the minute interval. Conventionally, ball bearings have been used for bearings of this type of motor. The ball bearing always generates vibration as the ball rotates. The vibration level is about 0.15 μm as measured by non-repeatable run-out (Non-Repeatable Run Out: NRRO) of the hub of the motor to which the magnetic disk is fixed. It is said that there is. When such a vibration occurs, the magnetic head is deviated from the track by the amount of the vibration displacement, which may have an adverse effect on data writing and reading, and the conventional ball bearing has reached its limit to satisfy the required performance. I have.
[0004]
Recently, a fixed shaft and a sleeve rotatably supported by the fixed shaft or a fixed sleeve and a rotatable shaft rotatably supported by the fixed shaft have been provided for the purpose of achieving the above-described high accuracy, as well as reducing noise and extending the life. In addition, motors in which a radial hydrodynamic bearing is formed have been proposed.
[0005]
As a motor provided with such a hydrodynamic bearing, for example, a motor disclosed in Japanese Patent Application Laid-Open No. 6-178489 is known.
[0006]
FIG. 16 shows a sectional view of this type of conventional motor. In FIG. 16, a fixed shaft 501 is vertically fixed to a central portion of a bracket 504, and a stator core 510 on which a winding is applied is also attached to the bracket 504. A rotor magnet 506 is fixed to the rotor frame 505 facing the stator core 510, and the rotor frame 505 is fixed to the hub 503. A bush 511 is fixed to an inner peripheral portion of a lower portion of the hub 503, and a bush 512 is attached to an outer peripheral portion of the bracket 504. The bush 511 and the bush 512 are opposed to each other with a gap. A magnetic disk (not shown) is mounted on the outer periphery of the hub 503.
[0007]
A dynamic pressure generating groove (not shown) for generating a dynamic pressure of the lubricating fluid by rotation is provided inside the sleeve 502, and the sleeve 502 rotates on the fixed shaft 501 via the lubricating fluid. The bearings are freely supported and constitute radial dynamic pressure fluid bearings R501 and R502. Axial dynamic bearings A501 and A502 are constituted by both end surfaces of the fixed thrust ring 507, the lower surface of the rotary thrust ring 508, and the upper surface of the sleeve 502. A concave groove 541 is provided on an outer peripheral portion of the cap 509, and a concave groove 542 is provided on an inner peripheral portion of the rotary thrust ring 508. The position of the lower edge of the groove 541 is substantially the center of the groove 542, the position of the upper edge of the groove 542 is substantially the center of the groove 541, and the position of both edges of the grooves 541 and 542 is They face each other differently.
[0008]
[Problems to be solved by the invention]
However, in a conventional motor equipped with this kind of hydrodynamic bearing, the lubricating fluid may be scattered in a space where the magnetic disk is located. Since data is written and read in this space with the magnetic head very close to the magnetic disk, the space must be kept extremely clean, and if the lubricating fluid flows out or scatters into the space, In such a case, serious problems such as head crash and head suction may occur. (Hereinafter, the above space is referred to as a clean space.)
In the conventional motor as well, as a measure for preventing the lubricating fluid from scattering into the clean space, an oil reservoir including the concave groove 541 and the concave groove 542 is provided so that the lubricating fluid does not come out from the upper part of the motor. There is a problem that it is not possible to shut off until the lubricating fluid flows out.
[0009]
The spindle device according to the present invention is provided with a mist seal that blocks outflow of mist-like lubricating fluid between the hydrodynamic bearing and the clean space where the magnetic disk is located, thereby avoiding problems such as head crash and head suction. It is an object of the present invention to provide a highly reliable spindle device that can perform the operation.
[0010]
[Means for Solving the Problems]
The present invention provides a bracket on which a stator core having a fixed shaft and a winding is mounted, a hub to which a disk is mounted and rotated, a rotor magnet mounted on the hub opposite to the stator core, and fixed to the hub. A spindle device that is rotatably supported on the fixed shaft via a lubricating fluid and has a sleeve that constitutes a radial dynamic pressure fluid bearing, comprising a thrust dynamic pressure fluid bearing on both end surfaces of the sleeve. Provided is a spindle device provided with a mist seal, such as a visco seal, a labyrinth seal, or a magnetic fluid seal, for blocking outflow of a mist-shaped lubricating fluid between a thrust hydrodynamic bearing and a clean space in which the disk exists. Things. According to the above configuration, it is possible to prevent the lubricating fluid in the form of a mist from being scattered in the clean space by the mist seal.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
The present invention provides a bracket on which a stator core having a fixed shaft and a winding is mounted, a hub to which a disk is mounted and rotated, a rotor magnet mounted on the hub opposite to the stator core, and fixed to the hub. A spindle device having a sleeve that is rotatably supported on the fixed shaft via a lubricating fluid and constitutes a radial dynamic pressure fluid bearing, wherein the sleeve device includes thrust dynamic pressure fluid bearings on both end surfaces of the sleeve. Provided is a spindle device provided with a mist seal, such as a visco seal, a labyrinth seal, or a magnetic fluid seal, for blocking outflow of a mist-shaped lubricating fluid between a thrust hydrodynamic bearing and a clean space in which the disk exists. Things. According to the above configuration, it is possible to prevent the lubricating fluid in the form of a mist from being scattered in the clean space by the mist seal.
[0012]
Further, by combining the oil seal for preventing the outflow of the lubricating fluid itself and the oil reservoir for preventing the outflow of the surplus lubricating fluid, it is possible to prevent the liquid lubricating fluid from flowing out to the clean space, An even more reliable spindle device can be realized.
[0013]
That is, the spindle device of the present invention is characterized by a seal configuration in which the lubricating fluid of the hydrodynamic bearing is not scattered into the clean space. The seal configuration from the dynamic pressure lubricating fluid bearing to the clean space is, for example, a dynamic pressure lubricating fluid bearing → oil seal (surface tension seal) → oil seal (centrifugal force seal) → mist seal (visco seal, magnetic fluid seal, labyrinth) Seal) → clean space, lubricating fluid is held in the hydrodynamic lubricating bearing by surface tension seal, lubricating fluid returned by centrifugal seal is returned, and lubricating fluid that becomes mist and scatters is scattered by mist seal This is very effective in preventing the lubricating fluid from flowing out and scattering. It should be noted that part of the seal configuration may be omitted from the viewpoint of the motor configuration.
[0014]
In addition, by providing an oil reservoir or a concave portion, a great effect can be expected not only in prevention of outflow due to continuous rotation, but also in prevention of outflow and scattering due to high-temperature standing, intermittent operation, a difference in posture.
[0015]
In addition, the thrust hydrodynamic bearings are formed on the upper and lower parts of the radial hydrodynamic bearing, so that the bearing span of the radial hydrodynamic bearing can be lengthened, rigidity can be improved, and a hydrodynamic bearing with good bearing balance can be obtained. There is also the effect that it can be done.
[0016]
Further, since the lubricating fluid does not flow out in the spindle device of the present invention, the hydrodynamic bearing is always filled with the lubricating fluid, which also has the effect of greatly extending the life time of the magnetic disk drive device.
[0017]
【Example】
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0018]
(Example 1)
FIG. 1 is a sectional view of a motor according to a first embodiment of the present invention, FIG. 2 is an enlarged view of the upper part of the motor, FIG. 3 is an enlarged view of the lower part of the motor, FIG. The detailed view of the hydrodynamic bearing is shown.
[0019]
1 to 5, a fixed shaft 1 is vertically fixed to a central portion of a bracket 4. The bracket 4 is provided with a projection and a hole for screw tightening so that the bracket 4 can be mounted on the apparatus main body, and a core holder 12 is attached. A stator core 11 on which a winding is applied is mounted on the outer peripheral surface of the core holder 12 at a position facing the rotor magnet 6 through a narrow gap.
[0020]
A magnetic disk (not shown) is mounted on an outer peripheral surface of the hub 3, and the cylindrical rotor magnet 6 is attached to an inner peripheral surface thereof via a cylindrical rotor frame 5. The sleeve 2 is attached to another inner peripheral surface of the hub 3, and a dynamic pressure generating groove 17 for generating a dynamic pressure of a lubricating fluid (not shown) by being rotated is provided inside the sleeve 2. . The sleeve 2 is rotatably supported on the fixed shaft 1 via a lubricating fluid, and constitutes radial dynamic pressure fluid bearings R1, R2.
[0021]
A rotary thrust ring 8 having a dynamic pressure generating groove 18 for generating a dynamic pressure of a lubricating fluid is fixed to an end surface of an upper end portion of the sleeve 2 and is fixed to the fixed shaft 1 via a lubricating fluid. The fixed thrust ring 7 is rotatably supported to form a thrust pressure fluid bearing A1. The dynamic pressure generating groove 18 may be provided on the fixed thrust ring 7 side. A rotary thrust ring 10 having a dynamic pressure generating groove (not shown) for generating a dynamic pressure of the lubricating fluid is fixed to an end surface of a lower end portion of the sleeve 2. 4 is rotatably supported by a fixed thrust ring 9 fixed to an end face of the end portion 4, and constitutes a thrust hydrodynamic bearing A2. The dynamic pressure generating groove may be provided on the fixed thrust ring 9 side.
[0022]
Further, a seal member 13 is fixed to the upper part of the rotary thrust ring 8 to the enclosing sleeve 2 which sandwiches the rotary thrust ring 8. The seal member 13 is provided with a tapered centrifugal seal 16 and an oil reservoir 30. The inner peripheral portion of the hub 3 and the outer peripheral portion of the fixed thrust ring 7 are opposed to each other with a small gap 15, and a screw is provided on the inner peripheral portion of the hub 3 for rotating to draw air from the clean space 29. A visco seal 14 is formed.
[0023]
Here, the visco-seal means that a screw is formed on an inner diameter side member or an outer diameter side member which forms a cylindrical space and forms the cylindrical space, and generates pressure by rotating, thereby causing the flow of air to flow through the magnetic disk. A mist-shaped lubricating fluid is generated from a certain clean space in the direction of the thrust hydrodynamic bearing so as not to scatter into the clean space, and is one specific example of a mist seal.
[0024]
A tapered centrifugal seal 21 is provided on the outer peripheral portion of the lower portion of the sleeve 2.
[0025]
Here, the centrifugal force seal uses the fact that the centrifugal force is proportional to the radius from the center of rotation, and by providing a taper, when the motor rotates, the centrifugal force causes the lubricating fluid to move toward the hydrodynamic bearing in the direction of the hydrodynamic bearing. This is to generate a flow to prevent the outflow of a liquid lubricating fluid, and is one of specific examples of an oil seal.
[0026]
The centrifugal seal 21 is provided on the outer periphery of the sleeve 21 which is a rotating body in order to further enhance the effect.
[0027]
Further, the lower outer peripheral portion of the sleeve 2 and the inner peripheral portion of the core holder 12 are opposed to each other with a minute gap 20, and the lower outer peripheral portion of the sleeve 2 is rotated to provide the stator core 11 and the rotor magnet 6 from the clean space 29. A visco seal 19 provided with a screw for drawing air through the space is formed.
[0028]
With the configuration described above, the outflow of the liquid lubricating fluid can be prevented by the centrifugal seals 16 and 21, and the lubricating fluid that is mist and scattered can be prevented from scattering into the clean space by the visco seals 14 and 19.
[0029]
Further, by providing a minute gap between the outer peripheral portion of the rotary thrust ring 10 and the inner peripheral portion of the core holder 12, a surface tension seal 24 as an oil seal is formed, and an oil reservoir 22 is provided in the core holder 12. I have.
[0030]
Thus, the prevention of the outflow of the lubricating fluid can be further enhanced.
By the way, the lubricating fluid is filled into the radial hydrodynamic bearings R1, R2 and the thrust hydrodynamic bearings A1, A2 at the time of assembly. When the motor is rotated, the lubricating fluid concentrates on the central portions of the radial hydrodynamic bearings R1, R2 and the thrust hydrodynamic bearings A1, A2. However, the flow of the surplus lubricating fluid is not determined, and may be scattered by centrifugal force or the like. In addition, bubbles may be entrained in the lubricating fluid during assembly, or if microscopic bubbles are contained in the lubricating fluid, the bubbles may grow due to temperature changes, and bubbles may be generated at locations where the pressure drops inside the hydrodynamic bearing due to rotation. Are gathered and grow, pushing up and scattering the lubricating fluid. Further, when the device is exposed to a high-temperature environment for a long period of time, the lubricating fluid tends to flow out. Even in such a case, the spindle device of the present invention can prevent the lubricating fluid from flowing out and scattering into the clean space 29 by the combination of the mist seal, the oil seal and the oil reservoir.
[0031]
(Example 2)
FIG. 6 is an enlarged view of the lower part of the motor according to the second embodiment of the present invention. In FIG. 6, a dynamic pressure generating groove (not shown) for generating a dynamic pressure of a lubricating fluid by rotation is provided inside a sleeve 52, and the sleeve 52 is provided with a fixed shaft via the lubricating fluid. 1 and rotatably supported, and constitutes a radial dynamic pressure fluid bearing R2. This embodiment differs from the first embodiment in that the tapered centrifugal seal 25, which is an oil seal provided on the outer periphery of the lower portion of the sleeve 52, has a large taper angle. In the lower portion of the sleeve 52, since the lubricating fluid is particularly likely to flow out by its own weight, it is preferable to increase the taper angle of the centrifugal seal 25 to increase its space.
[0032]
With the above configuration, the outflow of the lubricating fluid can be more reliably prevented.
[0033]
(Example 3)
FIG. 7 is a sectional view of a motor according to a third embodiment of the present invention, and FIG. 8 is an enlarged view of a lower portion of the motor.
[0034]
7 and 8, the present embodiment is different from the first or second embodiment in the following points. The wound stator core 11 is attached to a bracket 54, and a mount collar 62 is attached to a central inner peripheral portion of the bracket 54. The fixed collar 1 is fixed to the center of the mount collar 62, and the fixed thrust ring 60 is fixed to the end face. A dynamic pressure generating groove for generating a dynamic pressure of the lubricating fluid is provided in either the fixed thrust ring 60 or the rotary thrust ring 10 fixed to the sleeve 52. And a thrust hydrodynamic bearing A2 via a lubricating fluid. As in the first or second embodiment, the outflow of the lubricating fluid can be prevented.
[0035]
(Example 4)
FIG. 9 is a sectional view of a motor according to a fourth embodiment of the present invention.
[0036]
In FIG. 9, this embodiment is different from the first embodiment in the following points. The bracket 104 is provided with a sealing seal 26 for sealing a screw tightening hole or the like provided in the bracket 104. By providing a minute gap between the inner peripheral surface of the hub 3 and the outer peripheral surface of the bracket 104, a labyrinth seal 27 is provided as a mist seal.
[0037]
Usually, the labyrinth seal is composed of the minute gap and the expansion chamber. In other words, the space 28 in which the rotor core 11 and the rotor magnet 6 on which the windings are provided is arranged as an expansion chamber, and a small gap is formed between the inner peripheral surface of the hub 3 and the outer peripheral surface of the bracket 104 (usually, this kind of minute The gap is called a labyrinth seal.), The energy of the air flow is consumed in the expansion chamber 28, and the flow rate of the air is extremely reduced when passing through the minute gap, so that the mist-like lubrication to the clean space 29 is performed. Fluid scattering can be prevented.
[0038]
(Example 5)
FIG. 10 is a sectional view of a motor according to a fifth embodiment of the present invention, and FIG. 11 is an enlarged view of the upper part of the motor.
[0039]
10 and 11, a mount collar 212 is attached to a central inner peripheral portion of the bracket 204. A fixed shaft 301 is vertically fixed to the center of the mount collar 212. The bracket 204 is provided with a convex portion and a hole for screw tightening so that the bracket 204 can be mounted on the apparatus main body. A stator core 211 on which a winding is applied is mounted on the outer peripheral surface of the bracket 204 at a position facing the rotor magnet 206 via a narrow gap.
[0040]
A magnetic disk (not shown) is mounted on an outer peripheral surface of the hub 203, and the cylindrical rotor magnet 206 is mounted on an inner peripheral surface of the hub 203 via a cylindrical rotor frame 205. A magnetic shield plate 210 for preventing magnetic flux leakage is further attached to the inner peripheral surface of the hub 203. The sleeve 202 is attached to another inner peripheral surface of the hub 203, and a dynamic pressure generating groove (not shown) for generating a dynamic pressure of the lubricating fluid by rotating the sleeve 202 is provided inside the sleeve 202. . The sleeve 202 is rotatably supported on a fixed shaft 301 via a lubricating fluid, and forms radial dynamic pressure fluid bearings R201 and R202.
[0041]
At the upper end of the fixed shaft 301, a fixed thrust ring 207 having a dynamic pressure generating groove for generating a dynamic pressure of the lubricating fluid on both surfaces is sandwiched by the top screw 201 and fixed so as to satisfy coaxiality. A thrust hydrodynamic bearing A202 is formed between the sleeve 202 and the lower surface of the fixed thrust ring 207 via a lubricating fluid, and is rotatably supported. On the upper part of the fixed thrust ring 207, a rotary thrust ring 208 is fixed to the sleeve 202, and a thrust hydrodynamic fluid bearing is provided between the upper surface of the fixed thrust ring 207 and the lower surface of the rotary thrust ring 208 via a lubricating fluid. A201 is formed and rotatably supported.
[0042]
The outer peripheral portion of the top screw 201 and the inner peripheral portion of the member 209 for forming the visco seal 213 face each other with a minute gap 214 therebetween. On the upper part of the rotary thrust ring 208, a visco seal 213 having a screw provided on the inner peripheral portion of the member 209 is formed so as to draw air from the clean space 29 with the rotation. The visco-seal 213 can prevent the mist-like lubricating fluid from scattering.
[0043]
A minute gap 219 is formed between the inner peripheral surface of the sleeve 202 and the outer peripheral surface of the fixed thrust ring 207, and is filled with a lubricating fluid. The lubricating fluid is held by surface tension. Further, a minute gap 220 is also formed between the outer peripheral surface of the top screw 201 and the inner peripheral surface of the rotary thrust ring 208, and is filled with a lubricating fluid and held by surface tension.
[0044]
The outflow of the lubricating fluid can be prevented by the surface tension of the lubricating fluid, and the lubricating fluid scattered in the form of mist can be prevented from flowing above the rotary thrust ring 208. The outer peripheral surface of the top screw 201 may be the outer peripheral surface of the fixed shaft.
[0045]
Further, an oil reservoir 217 is provided between the rotary thrust ring 208 and the member 209 so that excess lubricating fluid on the inner peripheral portion of the rotary thrust ring 208 is transmitted to the surface of the rotary thrust ring 208 by centrifugal force and accumulated in the oil reservoir 217. It has become. Further, by providing the concave groove 218 in the top screw 201 facing the oil reservoir 217, even if the surplus lubricating fluid in the inner peripheral portion of the rotary thrust ring 208 flows out due to centrifugal force, it does not reach the clean space 29. You can do so. When left in an upside down position, the surplus lubricating fluid flows down the top screw 201 and flows down to reach the tip of the top screw 201. If the motor is rotated in this state, the lubricating fluid may be scattered into the clean space. However, by providing the concave groove 218 in the top screw 201, the lubricating fluid flowing down is collected in the concave groove 218 and stopped, and flows out to the clean space 29. Can be prevented.
[0046]
Further, a tapered centrifugal seal 225 is provided on the outer peripheral portion of the lower portion of the sleeve 202. To make the centrifugal seal 225 more effective, the centrifugal seal 225 is disposed on the outer periphery of the sleeve 202 as a rotating body to prevent the lubricating fluid from flowing out. An oil reservoir 221 is provided between the sleeve 202 and the magnetic shield plate 210, and an oil reservoir 226 is also provided between the rotor frame 205 and the magnetic shield plate 210. As a result, the excess lubricating fluid at the lower portion of the sleeve 202 tends to flow out to the outer peripheral side of the sleeve 202 due to centrifugal force, but the flow of the lubricating fluid can be stopped by the centrifugal seal 225.
[0047]
However, if there is a possibility that the oil will further flow along the outer peripheral surface of the sleeve 202, an oil reservoir 221 is provided between the sleeve 202 and the magnetic shield plate 210, and the oil pool 221 flows down the outer peripheral surface of the sleeve 202 from below. It tries to stop the surplus lubricating fluid coming. Further, even if the surplus lubricating fluid is transmitted to the magnetic shield plate 210 by the centrifugal force accompanying the rotation, an oil reservoir 226 is provided between the rotor frame 205 and the magnetic shield plate 210 in the middle of this outflow path, and the surplus lubrication is provided. The fluid is prevented from flowing into the clean space 29. A gap may be set in the oil reservoirs 221 and 226 so that the lubricating fluid can be held by its surface tension even if the rotation is repeatedly stopped.
[0048]
That is, even if the lubricating fluid attempts to flow out, the oil reservoir 221 and the oil reservoir 226 are provided, so that two-stage and three-stage outflow prevention measures are taken, and the outflow to the clean space 29 can be reliably prevented. .
[0049]
(Example 6)
FIG. 12 is a sectional view of a motor according to a sixth embodiment of the present invention, and FIG. 13 is an enlarged view of the upper part of the motor. 12 and 13, the present embodiment is different from the fifth embodiment in the following points. A magnetic fluid seal holder 309 is fixed to the sleeve 202 above the rotary thrust ring 208. A magnetic fluid seal 314 for holding the magnetic fluid 313 by magnetic force is fixed to the magnetic fluid seal holder 309.
[0050]
Here, the magnetic fluid seal 314 will be described. The magnetic fluid seal 314 has a sandwich structure in which an annular magnet 315 having N and S poles at both end surfaces is sandwiched between similar annular magnetic material pieces 316 and 317, and has a sandwich structure. It has a magnetic fluid 313 surrounded by the pieces 316 and 317. As shown in FIG. 13, the magnetic fluid 313 completely closes a minute gap between the outer peripheral surface of the top screw 201 and the end surface of the magnetic material piece 316 facing the outer peripheral surface. At this time, the following magnetic paths are formed. The magnetic flux generated from the magnet 315 passes through the magnetic material piece 316, the magnetic fluid 313, and the top screw 201, and passes through a minute gap between the outer peripheral surface of the top screw 201 and the end surface of the magnetic material piece 317 opposite to the outer peripheral surface. Through the magnetic material piece 317 and returns to the magnet 315. Such a magnetic path is formed, the magnetic fluid 313 is held, and the mist-like lubricating fluid can be prevented from scattering from the inner peripheral portion of the rotary thrust ring 208 to the clean space 29.
[0051]
In using a magnetic fluid seal, a magnetic fluid 313 may be ruptured due to a temperature change and a pressure difference because a substantially complete hermetic space 318 is formed. However, the volume of the hermetic space 318 may be reduced, and the rotation thrust may be reduced. By providing a minute gap 220 between the inner peripheral surface 208 of the ring and the outer peripheral surface 201 of the top screw and holding the lubricating fluid by surface tension, the level of the lubricating fluid changes and the pressure is balanced so that the magnetic fluid 313 can be balanced. Can be avoided. It is preferable to make the volume enclosed by the inner peripheral surface of the rotary thrust ring and the outer peripheral surface of the top screw larger than the volume of the closed space 318.
[0052]
Note that the top screw may be formed integrally with the fixed shaft.
[0053]
(Example 7)
FIG. 14 is a sectional view of a motor according to a seventh embodiment of the present invention.
[0054]
In FIG. 14, the bracket 304 is provided with a sealing seal 222 for sealing a screw tightening hole or the like provided in the bracket 304. By providing a minute gap between the inner peripheral surface of the hub 203 and the outer peripheral surface of the bracket 304, a labyrinth seal 223 is provided as a mist seal. As in the fourth embodiment, the space in which the stator core 211 and the rotor magnet 206 are located is the expansion chamber 224, so that the energy of the air flow is consumed in the expansion chamber 224 and the air flowing through the labyrinth seal 223. Is extremely reduced, so that the mist-like lubricating fluid can be prevented from scattering into the clean space 29.
[0055]
(Example 8)
FIG. 15 is a sectional view of a motor according to the eighth embodiment of the present invention.
[0056]
FIG. 15 is different from the seventh embodiment in that a magnetic fluid seal 314 is provided to further prevent the mist-like lubricating fluid from scattering from above the motor.
[0057]
As described above, according to the present invention, a mist seal for preventing scattering of a mist-like lubricating fluid, an oil seal for preventing outflow of lubricating fluid itself, and an oil sump for preventing outflow of excess lubricating fluid are combined. With this configuration, the lubricating fluid can be prevented from flowing out into the clean space, and a highly reliable spindle device can be realized.
[0058]
The spindle device of the present invention is applicable not only to magnetic disk drive devices but also to optical disk drive devices, CD-ROM drive devices, MD drive devices, DVD drive devices and other disk drive devices and devices other than disk drive devices. It is possible and its industrial value is great.
[0059]
Although the present invention has been described in connection with the various embodiments described above, it is to be understood that various other changes may be made.
[0060]
The embodiments used in the specification and the drawings do not limit the invention. Further, the details of the present embodiment do not limit the scope of the claims.
[0061]
【The invention's effect】
The motor of the present invention has high reliability in which the lubricating fluid of the hydrodynamic bearing is not scattered into the clean space. There is also a feature in the seal configuration, and the configuration from the dynamic pressure lubricating fluid bearing to the clean space is as follows: dynamic pressure lubricating fluid bearing → oil seal (surface tension seal) → oil seal (centrifugal force seal) → mist seal (visco seal, magnetic (Fluid seal, labyrinth seal) → It becomes a clean space, the lubricating fluid is held on the hydrodynamic bearing by the surface tension seal, the lubricating fluid returned by the centrifugal seal is returned, and the lubricating fluid that becomes mist and scatters is Since the mist seal prevents scattering, it is very effective for the outflow and scattering of the lubricating fluid. (Some parts of the seal structure may be omitted from the viewpoint of the motor structure.) Further, since the lubricating fluid does not flow out, the lubricating fluid is always filled in the hydrodynamic bearing, thereby greatly extending the life time of the magnetic disk drive. effective. Further, the provision of the oil reservoir or the concave portion has a great effect not only in preventing outflow due to continuous rotation but also in preventing outflow and scattering due to high temperature standing, intermittent operation, a difference in posture.
[0062]
In addition, the structure of the thrust hydrodynamic bearing at the upper and lower parts of the radial hydrodynamic bearing allows the bearing span of the upper and lower radial hydrodynamic bearings to be longer, increases rigidity, and provides a well-balanced hydrodynamic fluid bearing. can get.
[Brief description of the drawings]
FIG. 1 is a sectional view of a motor according to a first embodiment of the present invention.
FIG. 2 is an enlarged view of the upper part of the motor according to the first embodiment of the present invention.
FIG. 3 is an enlarged view of a lower portion of the motor according to the first embodiment of the present invention.
FIG. 4 is a detailed view of the inside of the sleeve according to the first embodiment of the present invention.
FIG. 5 is a detailed view of a thrust hydrodynamic bearing portion according to the first embodiment of the present invention.
FIG. 6 is an enlarged view of a lower portion of a motor according to a second embodiment of the present invention.
FIG. 7 is a sectional view of a motor according to a third embodiment of the present invention.
FIG. 8 is an enlarged view of a lower portion of a motor according to a third embodiment of the present invention.
FIG. 9 is a sectional view of a motor according to a fourth embodiment of the present invention.
FIG. 10 is a sectional view of a motor according to a fifth embodiment of the present invention.
FIG. 11 is an enlarged view of a motor upper part according to a fifth embodiment of the present invention.
FIG. 12 is a sectional view of a motor according to a sixth embodiment of the present invention.
FIG. 13 is an enlarged view of a motor upper part according to a sixth embodiment of the present invention.
FIG. 14 is a sectional view of a motor according to a seventh embodiment of the present invention.
FIG. 15 is a sectional view of a motor according to an eighth embodiment of the present invention.
FIG. 16 is a sectional view of a conventional motor.
[Explanation of symbols]
1 fixed axis
2 sleeve
3 hub
4 Bracket
5 Rotor frame
6 rotor magnet
7 Fixed thrust ring
8 rotating thrust ring
11 Stator core
14, 19 Visco seal
16, 21 Centrifugal seal

Claims (9)

A bracket to which a stator core having a fixed shaft and a winding is attached, a hub to which a disk is mounted and rotated, a rotor magnet attached to the hub facing the stator core, and a lubricating fluid fixed to the hub. And a sleeve that is rotatably supported on the fixed shaft via a fixed shaft and that constitutes a radial dynamic fluid bearing, comprising: a thrust dynamic fluid bearing on an end surface of the sleeve; The first seal means for blocking the outflow of the mist-like lubricating fluid, the second seal means for blocking the outflow of the lubricating fluid itself, and the oil sump are provided between the bearing and the space where the disk exists. Spindle device with combination. 2. The spindle device according to claim 1, wherein thrust hydrodynamic bearings are provided at both end surfaces of the sleeve, and first sealing means is provided between each of the thrust hydrodynamic bearings and the space where the disk exists. 2. The spindle device according to claim 1, further comprising: a thrust hydrodynamic bearing comprising a rotary thrust ring disposed on one end surface of the sleeve and a fixed thrust ring disposed on a fixed shaft portion. The spindle device according to claim 1, wherein the first sealing means is a Visco seal. The spindle device according to claim 1, wherein the second sealing means is a centrifugal seal. The spindle device according to claim 1, wherein a centrifugal seal is provided on an outer periphery of the sleeve. 2. The spindle device according to claim 1, further comprising a labyrinth seal provided with a minute gap between an inner peripheral surface of the hub and an outer peripheral surface of the bracket. A bracket to which a stator core having a fixed shaft and a winding is attached, a hub to which a disk is mounted and rotated, a rotor magnet attached to the hub facing the stator core, and a lubricating fluid fixed to the hub. And a sleeve that is rotatably supported on the fixed shaft via a shaft and that constitutes a radial dynamic pressure fluid bearing, the spindle device being disposed on the inner surface of the hub facing the stator core on which the winding is applied. A spindle device comprising a magnetic shield plate and an oil reservoir between the sleeve and the magnetic shield plate. A bracket to which a stator core having a fixed shaft and a winding is attached, a hub to which a disk is mounted and rotated, a rotor magnet attached to the hub facing the stator core, and a lubricating fluid fixed to the hub. And a sleeve that is rotatably supported on the fixed shaft via a shaft and that constitutes a radial dynamic pressure fluid bearing, the spindle device being disposed on the inner surface of the hub facing the stator core on which the winding is applied. A spindle device including a magnetic shield plate, a rotor frame fixed to an inner surface of the hub, and an oil reservoir between the magnetic shield plate and the rotor frame.

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