JP2008208968A - Fluid bearing type rotating device and recording medium control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fluid bearing type rotating device having high reliability while suppressing the evaporation of low-viscosity oil to the outside of a motor. <P>SOLUTION: The fluid bearing type rotating device comprises a shaft closed at one end and rotatably inserted into a sleeve having a bearing hole as an opening portion, and a cover member having an opening portion inserted through the shaft and covering the opening portion of the sleeve, wherein lubricant is held in a clearance among the shaft, the sleeve and the cover member, a tapered space is formed in at least a portion between the sleeve and the cover member so that it is axially narrower at a connection portion to the bearing hole and axially wider as located closer to the outer periphery of the sleeve, and an vent hole is formed in the outer periphery of the tapered space or outward therefrom. A film is provided at a position of covering the vent hole for air only to permeate therethrough. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a lubricant life in a hydrodynamic bearing type rotation device and a recording medium control device.

  In recent years, the memory capacity of optical disks and the like has increased explosively, and accordingly, in order to realize a high data transfer rate, a disk rotating device of a recording device is required to rotate with high accuracy and high speed. In general, a hydrodynamic bearing type rotating device suitable for high-speed rotation has been used for a rotating main shaft portion of these disk rotating devices because a bearing can be made thin.

  In a hydrodynamic bearing type rotating device, oil (oil) as a lubricant is interposed between a shaft and a sleeve, and a pumping pressure is generated during rotation by a dynamic pressure generating groove. Rotation drive. Since the hydrodynamic bearing type rotating device is non-contact, it has extremely low frictional resistance, and is highly durable and suitable for high-speed rotation.

On the other hand, there was also a problem that the lubricant (oil) leaked to the outside due to the impact of dropping the fluid bearing type rotating device or moving the air accumulated inside the bearing. It has been solved.

  A conventional fluid bearing type rotating device will be described with reference to FIG. FIG. 11 is a cross-sectional view showing an outline of the configuration of a conventional shaft rotation type hydrodynamic bearing type rotation device. In FIG. 11, the hydrodynamic bearing type rotating device includes a shaft 1, a sleeve 2, a thrust plate 4, a cover member 5, a base 6, a motor stator 7, a rotor magnet 8, a disk 9, a spacer 10, a clamper 11, a rotor hub 12, and a lubricant. 13 has an oil reservoir 15.

  The shaft 1 integrally has a flange (a flange portion) 3, and the shaft 1 is rotatably inserted into the bearing hole 2 </ b> A of the sleeve 2. Herringbone-shaped dynamic pressure generating grooves 1A and 1B are provided on the outer peripheral surface of the shaft 1, and dynamic pressure is generated on the surface of the flange 3 facing the sleeve 2 and the surface facing the flange 3 and the thrust plate 4. Grooves 1C and 1D are provided, respectively.

  The sleeve 2 includes a bearing hole 2A, a circulation hole 2B for discharging air mixed in the lubricant, and a flange housing portion 2D. The bearing hole 2A accommodates the shaft 1 rotatably, and the flange accommodating portion 2D accommodates the flange 3 of the shaft 1 rotatably. The circulation hole 2B is provided substantially parallel to the bearing hole 2A, and communicates the tapered groove 2C and the flange housing portion 2D. The tapered groove 2C has a predetermined gradient, is sufficiently shallow at the inner peripheral portion, and becomes deeper as it approaches the outer peripheral portion.

  The cover member 5 has a shaft hole 5A from which one end of the shaft 1 can project, a ventilation hole 5B, and a recess 5C, and covers the upper end surface on the opening side of the sleeve 2 to prevent the lubricant 13 from leaking. It is a substantially ring-shaped cover member provided, and has a ventilation hole 5 </ b> B that communicates the upper and lower surfaces of the cover member 5. The oil reservoir 15 is constituted by the upper end surface of the sleeve 2 and the lower surface of the cover member 5. The tapered groove 2C of the sleeve 2 and the lower surface of the cover member 5 form a tapered space.

The rotor hub 12 is fixed to the shaft 1, and the rotor magnet 8, the spacer 10 and the clamper 11 are fixed to the rotor hub 12. On the other hand, the base 6 and the thrust plate 4 are fixed to the sleeve 2, and the motor stator 7 is fixed to the base 6 so as to face the rotor magnet 8.
A lubricant 13 is interposed between the shaft 1 and the sleeve 2.

The operation of the conventional hydrodynamic bearing type rotating device configured as described above will be described.
When the motor stator 7 is energized, a rotating magnetic field is generated, and a rotational force is applied to the rotor magnet 8,
The rotor hub 12, the shaft 1, the clamper 11, the spacer 10, and the disk 9 start to rotate. By rotation, the dynamic pressure generating grooves 1 </ b> A to 1 </ b> D collect the lubricant 13 and generate pumping pressure between the shaft 1 and the sleeve 2 and between the shaft 1 and the thrust plate 4. As a result, the shaft 1 floats upward with respect to the sleeve 2 and rotates in a non-contact manner, and data on the disk 9 is recorded and reproduced by a magnetic head or an optical head (not shown).

  When air accumulates inside the lubricant 13, the air bubbles 14 move between the lower surface of the cover member 5 and the upper end surface of the sleeve 2 through the circulation hole 2 </ b> B. Since the cover member 5 is substantially ring-shaped, the air bubbles 14 circulate around the lower surface of the cover member 5 from the circulation hole 2B side to the ventilation hole 5B side, and are discharged to the outside from the ventilation hole 5B. Thereby, since the air bubbles 14 do not collect in the dynamic pressure generating grooves 1A to 1D, the oil film is not cut off in the dynamic pressure generating grooves 1A to 1D, and it is possible to prevent the rotation performance of the apparatus from being deteriorated.

In addition, when an impact load is applied to the hydrodynamic bearing type rotating device, the lubricant 13 is once guided from the bearing hole 1A to the tapered space and spreads in the outer circumferential direction in the tapered space. Since the taper-shaped space becomes wider in the axial direction as it is closer to the outer periphery, the space in which the space accommodates the lubricant expands, and the lubricant does not overflow from the ventilation hole. When the impact is settled, the lubricant is sucked by the capillary force toward the narrower cross section of the tapered space (in the direction of the bearing hole) and returns to the original bearing hole. There is no risk that some lubricant will remain in the tapered space and gradually reduce the lubricant in the bearing holes.
JP 2005-308057 A

However, in the fluid bearing type rotating device of the conventional example, since the lubricant filled in the tapered space inside the bearing of the cover member has a large surface area in contact with air through the ventilation hole, the lubricant evaporates quickly. There was a problem with reliability. In order to suppress evaporation, it is preferable to use the same viscosity. However, there is a disadvantage that the amount of current consumption increases due to an increase in bearing loss.
With the recent portability of signal recording / reproducing devices such as hard disk drive devices, there is an increasing demand for reducing power consumption, but conventional devices cannot cope with it.

  In view of the above-described problems, the present invention prevents the oil from evaporating to the outside of the motor even when low-viscosity oil capable of reducing power consumption is used, and a highly reliable fluid bearing rotating device, and a recording having the same An object is to provide a medium control device.

  In order to solve the above-described conventional problems, a hydrodynamic bearing type rotating device according to the present invention includes a sleeve having one end closed and a bearing hole as an opening, a shaft rotatably inserted in the bearing hole, A cover member having an opening through which the shaft is inserted and covering the opening side of the sleeve, and a lubricant is held in a gap between the shaft, the sleeve, and the cover member, and between the sleeve and the cover member Forming a tapered space having a narrow axial width at a connecting portion with the bearing hole and increasing in the axial direction as approaching the outer periphery of the sleeve, and forming an outer periphery of the tapered space. In the hydrodynamic bearing type rotating device having a ventilation hole in a part or outside, a film that allows only air to pass through is provided at a position covering the ventilation hole.

  The present invention saturates the space in the cover member with lubricating oil vapor with a film covering the ventilation holes, and covers the ventilation holes with a film that substantially allows only air to pass through, so that the evaporation area is equivalent to the cross-sectional area of the ventilation holes. Therefore, evaporation of the lubricant from the ventilation hole can be prevented without using a highly viscous lubricant with little evaporation.

  Further, even when low viscosity oil capable of reducing power consumption is used, the oil is prevented from evaporating to the outside of the motor, and a highly reliable fluid bearing rotating device can be realized. The bearing hole includes the flange storage portion of the embodiment.

  According to the present invention, even when a low viscosity lubricant (oil) capable of reducing power consumption is used, evaporation of the lubricant to the outside of the motor can be suppressed, and a highly reliable fluid bearing rotating device is realized. can do.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments that specifically show the best mode for carrying out the present invention will be described below with reference to the drawings.

(Embodiment 1)
The hydrodynamic bearing type rotation device and the recording medium control device according to the first embodiment will be described with reference to FIGS. The hydrodynamic bearing type rotating device in the first embodiment is a spindle motor that rotates a magnetic disk. The recording medium control apparatus according to the first embodiment is a disk apparatus that rotates a magnetic disk with the spindle motor according to the first embodiment. FIG. 1 is a cross-sectional view schematically illustrating a configuration of a shaft-rotating hydrodynamic bearing rotating device according to the first embodiment. In FIG. 1, 1 is a shaft, 2 is a sleeve, 4 is a thrust plate, 5 is a cover member, 6 is a base plate, 7 is a motor stator, 8 is a rotor magnet, 9 is a magnetic disk, 10 is a spacer, 11 is a clamper, 12 is a rotor hub, 13 is a lubricant, 15 is an oil reservoir, and 16 is a film.

The shaft 1 is rotatably accommodated in the bearing hole 2A of the sleeve 2, and has a flange 3 and dynamic pressure generating grooves 1A, 1B, and 1D. One end side (upper side in FIG. 1) of the shaft 1 slightly protrudes from the bearing hole 2A of the sleeve 2, and the rotor hub 12 is fixed at the protruding portion.
The flange 3 is integrally provided on the other end side (lower side in FIG. 1) of the shaft 1 and is rotatably accommodated in the flange accommodating portion 2D of the sleeve 2. The dynamic pressure generating grooves 1A and 1B are herringbone-shaped dynamic pressure generating grooves formed on the outer peripheral surface of the shaft 1, and form a radial bearing surface. The dynamic pressure generating grooves 1C and 1D are herringbone-shaped dynamic pressure generating grooves formed on the surface of the flange 3 facing the sleeve 2 and the surface of the flange 3 facing the thrust plate 4, respectively.

  The sleeve 2 has a bearing hole 2A, a circulation hole (communication hole) 2B, a tapered groove 2C, and a flange housing portion 2D. The bearing hole 2A and the flange storage portion 2D are provided in the approximate center of the sleeve, and are holes for rotatably storing the shaft 1 (including the flange 3). The circulation hole 2B is provided substantially parallel to the bearing hole 2A, and communicates the tapered groove 2C and the flange housing portion 2D. The tapered groove 2C has a predetermined gradient, is sufficiently shallow at the inner peripheral portion, and becomes deeper as it approaches the outer peripheral portion.

  The cover member 5 has a shaft hole 5A from which one end of the shaft 1 can project, a ventilation hole 5B, and a recess 5C, and covers the upper end surface on the opening side of the sleeve 2 to prevent the lubricant 13 from leaking. It is a substantially ring-shaped cover member provided. The shaft hole 5A is provided substantially at the center of the cover member. The recess 5C is a recess formed at a predetermined position on the surface of the cover member 5 on the sleeve 2 side (lower side in FIG. 1). The ventilation hole 5B is provided at a position close to the outer periphery of the cover member 5 with a predetermined size (for example, a diameter of about 0.3 mm). A filter 16 is attached to the upper end surface of the cover member 5 with an adhesive 17 at a position covering the ventilation hole 5B. The oil reservoir 15 is constituted by the upper end surface of the sleeve 2 and the lower surface of the cover member 5. The tapered groove 2C of the sleeve 2 and the lower surface of the cover member 5 form a tapered space.

  The filter 16 is a film that covers the upper end of the communication hole. Since the air particles are small at 0.3 to 0.6 nm and the oil particles are 3 to 6 nm and larger than air, the filter 16 is made of a material that does not allow oil molecules to pass therethrough and transmits only air molecules. Yes. Examples of such materials include, for example, reverse osmosis membranes (for nanofiltration and ultrafiltration) (Shimada), and porous films such as Timisch (Nitto Denko) and Sunmap (Nitto Denko). It is done. Moreover, microporous (Sumitomo 3M) and the like can also be mentioned.

The structure of the film mounting portion of the cover member 5, which is one of the features of the present invention, will be described with reference to FIGS. 2 and 3 (a). FIG. 2 is an enlarged cross-sectional view of an example of the film mounting portion of the cover member 5. FIG. 3A is a cross-sectional view showing an enlarged cross-sectional view of another example of the film mounting portion of the cover member 5.
The filter 16 in FIG. 2 may be fixed to the cover member 5 by positioning the filter 16 on the cover member 5 and fixing the outer peripheral portion with an adhesive 17 as shown in FIG. You may fix an outer peripheral part with the resin seal | sticker with an adhesive instead of an agent. By using a resin seal with an adhesive, there is no need for a burn-in or UV irradiation process, and the film covering the ventilation holes can be fixed in the final process after lubricating the fluid bearing type rotating device, and workability is improved. It can be simplified. Although not shown in FIG. 2, a recess may be formed in the cover member 5 and the filter 16 may be positioned and fixed. As a result, the outer peripheral portion is kept airtight, and the ventilation hole 5 </ b> B communicates with the outside air only through the filter 16.

  The filter recess 18 in FIG. 3A is composed of a two-stage recess, that is, a recess for mounting the filter and a recess for housing the resin seal 19 with adhesive for fixing the filter 16 as shown in the figure. In addition, only the recessed part which mounts the filter 16 may be sufficient. In this case, the filter 16 is first placed in the filter recess 18, and then the adhesive-attached resin seal 19 is pressed and pasted from above. As a result, the outer peripheral portion is kept airtight, and the ventilation hole 5 </ b> B communicates with the outside air only through the filter 16. In FIG. 3A, the filter 16 is fixed with a resin seal 19 with an adhesive. However, when a film material with poor adhesion is used or when the fixing strength of the film is increased, a metal pressing plate is used. Alternatively, a pressing plate made of resin may be fitted or bonded to the cover member 5. Further, in FIG. 3A, the filter 16 is fixed by the resin seal 19 with an adhesive, but may be fixed by an adhesive as shown in FIG.

  The filter recess 18 is provided by pressing or cutting by an end mill or the like. By fixing the filter in the recess provided in the cover member, a space for the filter is not required in the space above the cover member, and the present invention can be applied to a small and thin hydrodynamic bearing type rotating device.

  Refer to FIG. 1 again. The rotor hub 12 is fixed to the shaft 1, and the rotor magnet 8, the spacer 10 and the clamper 11 are fixed to the rotor hub 12. On the other hand, the base 6 and the thrust plate 4 are fixed to the sleeve 2, and the motor stator 7 is fixed to the base 6 so as to face the rotor magnet 8. The disk 9 is a detachable medium used for recording and / or reproduction. In FIG. 1, the disk 9 is mounted on the rotor hub 12 via a spacer 10 and fixed by a clamper 11. A lubricant 13 is interposed in the gap between the shaft 1 and the sleeve 2 and the gap between the shaft 1 and the thrust plate 4. The lubricant 13 is oil (oil).

Next, the operation of the hydrodynamic bearing type rotating device configured as described above will be described.
First, when the motor stator 7 is energized, a rotating magnetic field is generated, the rotor magnet 8 receives a rotational force, and starts rotating with the rotor hub 12, the shaft 1, the disk 9, the clamper 11, and the spacer 10. By rotation, the herringbone-shaped dynamic pressure generating grooves 1 </ b> A to 1 </ b> D collect the lubricant 13, between the shaft 1 and the sleeve 2, between the flange 3 and the sleeve 2, and between the flange 3 and the thrust plate 4. Generate pumping pressure. Thus, the shaft 1 floats upward with respect to the sleeve 2 and rotates in a non-contact manner, and data on the disk 9 is recorded and reproduced by a recording / reproducing head (not shown).

Next, the operation of the hydrodynamic bearing type rotating device of the present embodiment will be described with reference to FIGS. 4 and 5. First, as shown in FIG. 4, dimensions and gap distances D1 to D7 are defined.
In the lubricant held in the tapered space formed by the diameter D1 of the shaft 1 and the tapered groove 2C and the lower surface of the cover member 5, the lubricant held near the ventilation hole 5B from the center of the shaft 1 The distance in the horizontal direction from the center of the shaft 1 of the lubricant held in the vicinity of the ventilation hole 5B in the lubricant held in the tapered space formed by the distance D2, the tapered groove 2C and the lower surface of the cover member 5 D2 is the lubricant held in the tapered space formed by the tapered groove 2C and the lower surface of the cover member 5, and the axial distance of the lubricant held in the vicinity of the ventilation hole 5B is D3, the tapered groove In the lubricant held in the tapered space formed by 2C and the lower surface of the cover member 5, the horizontal from the center of the shaft 1 of the lubricant held in the vicinity of the side facing the ventilation hole 5B in the horizontal direction. Direction distance D4, the lubricant held in the tapered space formed by the tapered groove 2C and the lower surface of the cover member 5, the lubricant held in the vicinity of the side facing the ventilation hole 5B in the horizontal direction. The axial distance is D5, the radial gap distance (the axial width) between the outer peripheral surface of the shaft 1 and the inner peripheral surface of the cover member 5 is D6, and the diameter of the ventilation hole 5B provided in the cover member 5 is D7. . From these dimensions and gap distances D1 to D7, calculation formulas and approximate formulas for the respective areas S1 to S3 defined below are expressed.

The area of the surface formed by the radial gap between the outer peripheral surface of the shaft 1 and the inner peripheral surface of the cover member 5 is S1, the area of the ventilation hole 5B is S2, and the tapered groove 2C and the lower surface of the cover member 5 are When the circumferential area of the lubricant held in the tapered space configured: S3,
Formula for calculating S1: S1 = (D1 / 2 + D6) ² × π− (D1 / 2) ² × π
Formula for calculating S2: S2 = (D7 / 2) ² × π
Approximate formula of S3: S3 = D2 × D3 × π + D4 × D5 × π
It becomes.

In the conventional hydrodynamic bearing type rotating device (FIG. 9), the evaporation of the lubricant held in the tapered space formed by the tapered groove 2C and the lower surface of the cover member 5 is represented by the above equations S1 and S3. Occurs from the contact surface with the air expressed as the total area. On the other hand, in the hydrodynamic bearing type rotating device (FIG. 1) of the present invention, the evaporation of the lubricant held in the tapered space formed by the tapered groove 2C and the lower surface of the cover member 5 is expressed by the above equation S1. It occurs from the contact surface with the air expressed by the sum of the areas indicated by S2.
Since the ventilation hole is filled with oil vapor by the film, the contact area with the air related to evaporation can be considered as the ventilation hole area S2.

  Here, in the present embodiment, for example, each dimension is D1 = 3 mm, D2 = 3.8 mm, D3 = 0.15 mm, D4 = 4.4 mm, D5 = 0.2 mm, D6 = 0.1 mm, D7 = Set to 0.3 mm.

  FIG. 5 shows the relationship between the air contact area (S1 + S3) of the lubricant of the conventional hydrodynamic bearing type rotating device and the evaporation life of the lubricant and the lubrication of the hydrodynamic bearing type rotating device of the present invention in the above dimensions and gap distances D1 to D6. The graph which shows the relationship between the air contact area (S1 + S2) of an agent and the evaporation lifetime of a lubricant is shown. The vertical axis represents the air contact area, and the horizontal axis represents the lubricant evaporation life ratio when the lubricant evaporation life of the conventional hydrodynamic bearing type rotating device is 1. The amount of lubricant is the same for the conventional hydrodynamic bearing type rotary device and the hydrodynamic bearing type rotary device of the present invention, and the area surrounded by the straight line and the horizontal axis of the graph shown in FIG. 5 is the same. Can be explained.

  From the graph of FIG. 5, it can be seen that the evaporation life of the lubricant of the hydrodynamic bearing type rotating device of the present invention can be about three times longer than that of the lubricant of the conventional hydrodynamic bearing type rotating device. .

This makes it possible to extend the evaporation life of the lubricant without using a high-viscosity lubricant with little evaporation. Further, since the lubricant 13 circulates from the circulation hole 2B side to the recess 5C side along the outer peripheral edge of the oil reservoir portion 15 by capillary force, lubrication is performed even when an impact load is applied to the hydrodynamic bearing type rotating device. The agent 13 is not discharged out of the ventilation hole 5 </ b> B, and the film is not immersed in the lubricant 13. Only the air bubbles 14 are smoothly discharged outside the bearing.
In FIGS. 1 to 4, the tapered space is the most part of the sleeve and the cover member. However, it is sufficient if gas-liquid separation is possible, so that at least a part of the tapered space has the shape as shown in FIG. Good. The tapered portion may be formed on the cover member side.
As described above, according to the present embodiment, even when a low-viscosity oil capable of reducing power consumption is used without using a higher-viscosity lubricant having good evaporation resistance, the oil is also external to the motor. The fluid bearing rotating device with high reliability can be realized.

(Embodiment 2)
The hydrodynamic bearing type rotating device according to the second embodiment will be described with reference to FIGS. The hydrodynamic bearing type rotating device in the second embodiment is a spindle motor that rotates a magnetic disk. The recording medium control apparatus according to the second embodiment is a disk apparatus that rotates a magnetic disk with the spindle motor according to the second embodiment. FIG. 6 is a cross-sectional view schematically showing the configuration of the hydrodynamic bearing type rotating device in the present embodiment. 6 differs from the first embodiment in that a cover member 5 ′ is provided instead of the cover member 5. The other points are the same, and a detailed description of elements having the same reference numerals is omitted.

FIG. 7 illustrates the structure of the cover member 5 ′ in the present embodiment. FIG. 7 is an enlarged cross-sectional view of an example of the film mounting portion of the cover member 5 ′.
The cover member 5 ′ has a shaft hole 5A, a ventilation hole 5B ′, and a recess 5C. The shaft hole 5A and the recessed portion 5C are the same as the cover member 5 in the first embodiment shown in FIGS. 1, 2, and 3A and 3B. Ventilation hole 5B 'is provided in the side surface of cover member 5'. Further, a recess for accommodating the filter 16 is provided at the position of the ventilation hole 5B ′ on the side surface of the cover member 5 ′, and the filter 16 is fixed by a resin seal 19 with an adhesive. Oil molecules are not allowed to pass through the filter 16, and substantially only air can permeate, and evaporation of the lubricant can be suppressed.

  The hydrodynamic bearing type rotating device of the second embodiment has the same effects as those of the first embodiment.

(Embodiment 3)
The hydrodynamic bearing type rotating device in the third embodiment will be described with reference to FIG. The hydrodynamic bearing type rotation device in the third embodiment is a spindle motor that rotates a magnetic disk. The recording medium control apparatus according to the third embodiment is a disk apparatus that rotates a magnetic disk with the spindle motor according to the third embodiment. FIG. 8 is a cross-sectional view schematically showing the configuration of the hydrodynamic bearing type rotating device in the present embodiment. In FIG. 8, the hydrodynamic bearing type rotating device is different from the first embodiment in that the hydrodynamic bearing type rotating device is a shaft fixed type instead of the shaft rotating type. That is, the shaft 1 is fixed to the base 6 instead of being fixed to the rotor hub 12, while the rotor hub 12 is fixed to the sleeve 2. The other points are the same, and a detailed description of elements having the same reference numerals is omitted.

  When the motor stator 7 is energized, a rotating magnetic field is generated, the rotor magnet 8 receives a rotational force, and starts rotating together with the rotor hub 12, the sleeve 2, the thrust plate 4, the disk 9, the clamper 11, and the spacer 10. By rotation, the herringbone-shaped dynamic pressure generating grooves 1 </ b> A to 1 </ b> D collect the lubricant 13 and generate a pumping pressure between the shaft 1 and the sleeve 2 and between the flange 3 and the thrust plate 4. As a result, the sleeve 2 floats upward with respect to the shaft 1 and rotates in a non-contact manner, and data on the disk 9 is recorded and reproduced by a recording / reproducing head (not shown).

  Even when an impact load is applied, the lubricant 13 in the vicinity of the oil sump 15 is sucked to the narrower cross section of the tapered space (in the direction of the bearing hole) due to the strong capillary force, and thus flows out of the ventilation hole 13. There is no. The filter 16 does not allow oil molecules to pass therethrough and allows only air to permeate substantially, thereby suppressing evaporation of the lubricant.

  The hydrodynamic bearing type rotating device of the third embodiment has the same effects as the first and second embodiments.

  In the embodiment of the present invention, the hydrodynamic bearing type rotation device is a spindle motor, and the recording medium control device is a disk device that rotates a magnetic disk by the spindle motor. However, the present invention is not limited to this, and the hydrodynamic bearing type rotation device and the recording medium control device may be arbitrary devices. For example, the recording medium controlled by the recording medium control device is an optical recording medium, a magneto-optical recording medium, a magnetic recording medium, or the like. The recording medium may be a removable medium such as a DVD disk or a non-removable medium such as a hard disk device. It may be a disk-shaped recording medium or a tape-shaped recording medium. The hydrodynamic bearing rotating device includes, for example, a rotating head in a disk rotation driving device, a reel rotation driving device for a tape-shaped recording medium, a capstan rotation driving device for driving a tape, and a helical scan type recording (or reproducing) device. It is an arbitrary device such as a drum rotation driving device. The hydrodynamic bearing type rotating device of the present invention can also be applied to any device other than the recording medium control device.

  The hydrodynamic bearing type rotating device according to the present invention can be used for a spindle motor such as a magnetic disk device, for example. The recording medium control device according to the present invention can be used in, for example, a magneto-optical disk device, a hard disk device, and the like.

Sectional drawing which shows the outline of a structure of the fluid-bearing type rotating apparatus in Embodiment 1 of this invention. Sectional drawing which shows the expanded sectional view of an example of the cover member 5 of the hydrodynamic bearing type rotating apparatus in Embodiment 1 of this invention (A) Sectional drawing which shows the expanded sectional view of the other example of the cover member 5 of the fluid-bearing type rotating apparatus in Embodiment 1 of this invention, (b) Of the hydrodynamic bearing type rotating apparatus in Embodiment 1 of this invention Sectional drawing which shows the expanded sectional view of another example of the cover member 5 Sectional drawing which shows the dimension D1-D7 in Embodiment 1 of this invention The figure explaining the improvement effect of the oil evaporation lifetime in Embodiment 1 of this invention Sectional drawing which shows the outline of a structure of the fluid-bearing type rotating apparatus in Embodiment 2 of this invention. Sectional drawing which shows the expanded sectional view of the cover member 5 'of the hydrodynamic bearing type rotating device in Embodiment 2 of this invention Sectional drawing which shows the outline of a structure of the fluid-bearing type rotating apparatus in Embodiment 3 of this invention. The figure which shows the outline of a structure of the hydrodynamic bearing type rotating apparatus of a prior art example.

Explanation of symbols

1 shaft 1A, 1B, 1C, 1D dynamic pressure generating groove 2 sleeve 2A bearing hole 2B circulation hole 2C tapered groove 2D flange housing part 2E straight groove part 3 flange 4 thrust plate 5 cover member 5A shaft hole 5B ventilation hole 5C recess 5D first 2 recess 6 base plate 7 motor stator 8 rotor magnet 9 disk 10 spacer 11 clamper 12 rotor hub 13, 13 'lubricant 14 air 15 oil reservoir 16 film 17 adhesive 18 film recess 19 adhesive seal with adhesive

Claims (5)

A sleeve having a bearing hole which is closed at one end and is an opening;
A shaft rotatably inserted into the bearing hole;
A cover member having an opening through which the shaft is inserted and covering the opening side of the sleeve;
A lubricant is held in a gap between the shaft, the sleeve, and the cover member,
A tapered space is formed in at least a part between the sleeve and the cover member so that the axial width is narrow at the connection portion with the bearing hole, and the axial width becomes wider as the outer periphery of the sleeve is approached. And
In the hydrodynamic bearing type rotating device having a ventilation hole on the outer periphery or outside of the tapered space,
Provided with a film that allows only air to pass through the position covering the ventilation hole,
A hydrodynamic bearing type rotating device.   The hydrodynamic bearing type rotating device according to claim 1, wherein the film is fixed to the cover member by a resin seal with an adhesive.   The hydrodynamic bearing type rotating device according to claim 1, wherein the film is fixed to the cover member by a pressing plate made of metal or resin.   4. The hydrodynamic bearing type rotating device according to claim 1, wherein a recess for storing the film is provided in the vicinity of the ventilation hole of the cover member. 5. A recording medium control apparatus for recording and / or reproducing a tape-shaped or disk-shaped recording medium, comprising the hydrodynamic bearing type rotating device according to any one of claims 1 to 4.

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