JP2005114021A - Dynamic-pressure bearing device and disk driving device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To excellently prevent the generation or growth of bubbles with simple structure when filling a lubricating fluid. <P>SOLUTION: At least one of loose-out stopper members 13b and 25 provided in a fixing member 13 and a rotary member 21 rotatably supported by the fixing member 13 through a dynamic-pressure bearing parts RB and SB is provided with a fluid filling passage S3, which practically enlarges a passage area of narrow clearance passages S1 and S2 between both the loose-out stopper members 13b and 25, to reduce flowing resistance of the lubricating fluid in the narrow clearance passages S1 and S2, and the lubricating fluid can be quickly and early filled into a bearing space through the narrow clearance passages S1 and S2 and the fluid filling passage S3. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a dynamic pressure bearing device and a disk drive device including a mechanism for preventing a rotating member supported by a dynamic pressure with respect to a fixed member from being detached in the axial direction.

  In recent years, as a bearing device for rotating a rotating body at high speed and high accuracy in various rotary drive devices, development of a hydrodynamic bearing device that generates a dynamic pressure in a lubricating fluid and supports a rotating shaft in a non-contact manner has been advanced. Yes. For example, the hydrodynamic bearing device shown in FIG. 10 has a structure which is proposed by the following Patent Document 1 which has not been disclosed at the time of filing of the present application, and is shown in FIG. In the hydrodynamic bearing device, a rotating member (rotating hub) 3 is joined to a rotating shaft 2 rotatably supported by a hydrodynamic bearing member (bearing sleeve) 1 and the center of the rotating member 3 is connected. The axially inner end surface (lower surface side in FIG. 10) in the region and the axial outer end surface (upper end surface in FIG. 10) of the dynamic pressure bearing member 1 are disposed so as to be close to each other, and the thrust A thrust dynamic pressure bearing portion SB is formed in a part of the facing region.

  An appropriate lubricating fluid (not shown) is injected into the inside of the bearing space in the thrust dynamic pressure bearing portion SB, and as a dynamic pressure generating means for the lubricating fluid, for example, a spiral-shaped dynamic pressure generating groove is provided. It is recessed so as to be arranged in parallel along the circumferential direction, and a dynamic pressure is generated with respect to the lubricating fluid by the pressurizing action of the dynamic pressure generating groove so as to obtain a desired thrust levitation force.

  Further, two radial dynamic pressure bearing portions RB and RB are formed along the axial direction in a radial facing region where the inner peripheral side wall surface of the dynamic pressure bearing member 1 and the outer peripheral side wall surface of the rotary shaft 2 are opposed to each other. A lubricating fluid (not shown) is continuously injected from the above-described thrust dynamic pressure bearing portion SB into the bearing space of each radial dynamic pressure bearing portion RB. As the dynamic pressure generating means for the lubricating fluid, for example, herringbone-shaped dynamic pressure generating grooves are recessed so as to be juxtaposed along the circumferential direction, and the lubricating fluid is pressed by the pressurizing action of the dynamic pressure generating grooves. Is generated to obtain a desired radial levitation force.

  As described above, in the hydrodynamic bearing device according to the above-described proposal, the bearing space from the two radial hydrodynamic bearing portions RB and RB to the thrust hydrodynamic bearing portion SB is formed to be continuous. Although the lubricating fluid is continuously injected into the bearing space, the outer end portion of the continuous bearing space including the plurality of dynamic pressure bearing portions RB, RB, SB, that is, the thrust dynamic pressure bearing described above. A fluid seal portion CS for preventing external leakage of the lubricating fluid filled in the bearing space is provided on the radially outer side portion of the portion SB.

  The illustrated fluid seal portion CS is configured to have a composite seal structure that uses both the capillary force and the rotational centrifugal force of the lubricant to push the lubricant toward the bearing space. In addition, a connecting connection portion extending from the fluid seal portion CS to the outer end portion of the bearing space is joined so as to rotate integrally with a bearing sleeve (bearing member) 1 as a fixed member and a rotating shaft 2 as a rotating member. The rotation hub 3 is provided with retaining members 1a and 3a. Both the retaining members 1a and 3a are disposed in close proximity to each other so as to form narrow gap passages S10 and S11 in the axial direction, whereby the rotating shaft 2 and the rotating hub 3 as the rotating member are arranged. Is configured to prevent axial detachment.

Japanese Patent Application 2002-170619

  On the other hand, in the hydrodynamic bearing device having such a structure, in order to stably obtain good hydrodynamic characteristics for the lubricating fluid, the bearing space including the hydrodynamic bearing portions RB, RB, SB described above is filled. It is necessary to generate bubbles in the generated lubricating fluid and to suppress the growth of the generated bubbles. Therefore, conventionally, the design which makes the clearance gap of the said bearing space and the space connected to it as small as possible is performed. However, when the gap between the bearing space and the space communicating with the bearing space is reduced in this way, when the lubricating fluid is injected into the bearing space from the outside, the narrow gap portion described above with respect to the flow of the lubricating fluid is reduced. It becomes resistance, and it takes time until the lubricating fluid is completely filled in the bearing space.

  In particular, in the narrow gap passages S10 and S11 formed in the facing gap between the retaining members 1a and 3a described above, it takes a considerable time to move the lubricating fluid. As a result, before the lubricating fluid is completely filled in the bearing space, air may be bubbled into the bearing space, causing the behavior of the lubricating fluid to become unstable and reducing the dynamic pressure characteristics. There is.

  Accordingly, an object of the present invention is to provide a fluid dynamic bearing device and a disk drive device which can prevent the generation of bubbles well with a simple configuration and can obtain a stable dynamic pressure characteristic over a long period of time.

In order to achieve the above object, in the hydrodynamic bearing device according to claim 1 of the present invention, both the fixed member and the rotating member rotatably supported by the fixed member via the hydrodynamic bearing portion are provided. A fluid injection passage that substantially enlarges the passage area of the narrow gap passage between the two retaining members is provided on at least one side of the retaining member.
According to the hydrodynamic bearing device according to claim 1 of the present invention having such a configuration, the fluid injection passage is attached to the narrow gap passage formed in the opposing gap between the two retaining members. Since the passage area of the narrow gap passage is enlarged and the flow resistance of the lubricating fluid is reduced, the lubricating fluid quickly passes through the narrow gap passage and the fluid injection passage and is quickly injected into the bearing space. It has come to be.

In the fluid dynamic bearing device according to claim 2 of the present invention, either one of the fixed member and the rotating member in claim 1 includes the bearing member, and the other side of the fixed member and the rotating member is the above The shaft member is inserted into the inner side of the bearing member so as to be relatively rotatable, and the retaining member is provided with respect to the bearing member and the shaft member or the members integrally joined to the both members. .
According to the fluid dynamic bearing device according to the second aspect of the present invention having such a configuration, the above-described operation is the same in both the fluid dynamic bearing device having the shaft rotation structure and the fluid dynamic bearing device having the shaft fixed structure. Is obtained.

Further, in the hydrodynamic bearing device according to claim 3 of the present invention, the narrow gap passage formed between the both retaining members in claim 1 is such that the fixed member and the rotating member are close to each other in the axial direction. The thrust dynamic pressure bearing portion formed by being opposed to each other is provided at a portion adjacent to the radially outer end side with respect to the radially outer end portion, and a fluid injection passage is attached to the narrow gap passage. Yes.
According to the fluid dynamic bearing device according to claim 3 of the present invention having such a configuration, a so-called single thrust structure in which a retaining member is disposed in a portion adjacent to the thrust fluid dynamic bearing portion in the radial direction. The above-described operation can be similarly obtained in the hydrodynamic bearing device.

On the other hand, in a disk drive device according to a fourth aspect of the present invention, a spindle motor comprising the hydrodynamic bearing device according to any one of the first to third aspects, and an information recording disk mounted on the rotor of the spindle motor And a recording head for recording or reproducing information on the information recording disk.
According to the disk drive device according to the fourth aspect having such a configuration, the above-described good operation can be achieved also in the recording disk drive device.

  As described above, the hydrodynamic bearing device according to the present invention includes at least a retaining member provided on each of the fixing member and the rotating member rotatably supported by the fixing member via the hydrodynamic bearing portion. By providing a fluid injection passage on one side that substantially enlarges the passage area of the narrow gap passage between these two retaining members, the flow resistance of the lubricating fluid in the narrow gap passage is reduced, and these narrow passages are reduced. Since the lubricating fluid can be quickly and quickly injected into the bearing space through the clearance passage and the fluid injection passage, the simple structure can satisfactorily prevent the generation of bubbles when injecting the lubricating fluid. Since stable dynamic pressure characteristics can be obtained over a long period of time, the reliability of the dynamic pressure bearing device can be greatly improved.

  Further, the disk drive device according to the present invention is configured such that the information recording disk is rotationally driven by a spindle motor provided with the above-described hydrodynamic bearing device according to the present invention, and information is recorded or reproduced by a recording head. The remarkable effect in the pressure bearing device can be obtained in the recording disk drive device as well.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Prior to that, an outline of a spindle motor for a hard disk drive (HDD) as an example adopting a hydrodynamic bearing device to which the present invention is applied will be described. Will be explained.

  The entire spindle rotation / outer rotor type spindle motor shown in FIG. 1 includes a stator assembly 10 as a fixed side portion and a rotor assembly as a rotation side portion assembled to the stator assembly 10 from above. 20 is included.

  The stator assembly 10 has a base frame 11 that is screwed to a main body plate of a hard disk drive (HDD) (not shown). The base frame 11 is made of an aluminum-based metal material in order to reduce the weight, but the inner peripheral surface of the annular bearing holder 12 formed so as to stand upright at a substantially central portion of the fixed frame 11. On the side, a bearing sleeve 13 as a dynamic pressure bearing member formed in a hollow cylindrical shape is joined by press fitting or shrink fitting. The bearing sleeve 13 is made of a copper-based material such as phosphor bronze in order to facilitate drilling of a small diameter.

  A stator core 14 made of a laminate of electromagnetic steel sheets is fitted on the core mounting surface provided on the outer peripheral side wall surface of the bearing holder 12, and each salient pole portion provided on the stator core 14 has Each of the drive coils 15 is wound.

  Further, a rotary shaft 21 constituting the above-described rotor set 20 is rotatably inserted into a center hole provided in the bearing sleeve 13 as the dynamic pressure bearing member. That is, the dynamic pressure surface formed on the inner peripheral wall portion of the bearing sleeve 13 is disposed so as to face the dynamic pressure surface formed on the outer peripheral surface of the rotating shaft 21 in the radial direction, and from the minute gap Two radial dynamic pressure bearing portions RB, RB are formed in the bearing space portion with an appropriate interval in the axial direction. More specifically, the dynamic pressure surface on the bearing sleeve 13 side and the dynamic pressure surface on the rotating shaft 21 side in the radial dynamic pressure bearing portion RB are opposed to each other in a circumferential manner through a minute gap of several μm. Lubricating fluid such as lubricating oil or magnetic fluid is injected or interposed in the bearing space consisting of minute gaps so as to continue in the axial direction.

  Furthermore, at least one side of both the dynamic pressure surfaces of the bearing sleeve 13 and the rotating shaft 21 is appropriately formed of an annular assembly of herringbone-like bent grooves formed so as to have a substantially “<” shape, for example. The radial dynamic pressure generating groove of the structure is divided into two blocks in the axial direction and is annularly recessed. When rotating, the lubricating fluid, not shown, is pressurized by the pumping action of the radial dynamic pressure generating groove As a result, dynamic pressure is generated, and the rotary hub 22 described later together with the rotary shaft 21 is axially supported in a non-contact state in the radial direction with respect to the bearing sleeve 13 by the dynamic pressure of the lubricating fluid. .

  On the other hand, the rotating hub 22 that constitutes the rotor set 20 together with the rotating shaft 21 is formed of a substantially cup-shaped member made of ferritic stainless steel, and a joint hole 22 a provided in the central portion of the rotating hub 22. Are integrally joined to the upper end portion of the rotary shaft 21 in the drawing by press-fitting or shrink fitting. The rotating hub 22 has a substantially cylindrical main body 22b on which a recording medium disk such as a magnetic disk (not shown) is mounted on the outer periphery, and projects radially outward from the main body 22b. And a recording medium disk 22c for supporting the recording medium disk in the axial direction. The recording medium disk is pressed by a clamper (not shown) screwed so as to cover the recording medium disk from above. Is supposed to be fixed.

  An annular drive magnet 22d is attached to the inner peripheral wall surface side of the main body barrel 22b of the rotary hub 22. The inner peripheral surface of the annular drive magnet 22d is disposed close to the outer peripheral side end surface of each salient pole portion of the stator core 14 so as to be annularly opposed, and the lower end surface in the axial direction of the annular drive magnet 22d. Is in a positional relationship facing the magnetic attraction plate 16 attached to the above-described fixed frame 11 side in the axial direction, and the above-described rotary hub 22 is caused by the magnetic attraction force between these two members 22d and 16. Is attracted in the axial direction so that a stable rotational state can be obtained.

  Further, the opening provided on the lower end side of the bearing sleeve 13 is closed by a cover 13a so that the lubricating fluid in each of the radial dynamic pressure bearing portions RB described above does not leak to the outside.

  Furthermore, the hydrodynamic bearing device according to the present embodiment has a so-called single thrust structure, and the illustrated upper end surface of the bearing sleeve 13 and the illustrated lower end surface in the central side portion of the rotating hub 22 described above are shafts. It arrange | positions so that it may oppose to an axial direction in the state which adjoined to the direction. The thrust facing region between the upper end surface of the bearing sleeve 13 and the lower end surface of the rotating hub 22 is formed in a bearing space that is continuous from the above-described radial dynamic pressure bearing portion RB. A thrust dynamic pressure bearing portion SB is provided in a bearing space continuing from the dynamic pressure bearing portion RB. That is, a spiral or herringbone-shaped thrust dynamic pressure generating groove is formed on at least one side of the opposing dynamic pressure surfaces 13 and 22 constituting the thrust opposing region, and the thrust dynamic pressure generating groove Is formed in the thrust dynamic pressure bearing portion SB, so that the dynamic pressure bearing device has a so-called single thrust structure.

  A small gap of several μm is present between the dynamic pressure surface on the upper end surface side of the bearing sleeve 13 constituting the thrust dynamic pressure bearing portion SB and the dynamic pressure surface on the lower end surface side of the rotating hub 22 that is adjacent to and opposite to the dynamic pressure surface. And a lubricating fluid such as oil or magnetic fluid is continuously filled from the above-described radial dynamic pressure bearing portion RB in the bearing space formed by the minute gap and rotated. Occasionally, the lubricating fluid is pressurized by the pumping action of the thrust dynamic pressure generating groove described above to generate dynamic pressure, and the rotating shaft 21 and the rotating hub 22 float in the thrust direction by the dynamic pressure of the lubricating fluid. The shaft is supported in a state.

  The thrust dynamic pressure generating groove at this time is formed in a thrust dynamic pressure generating groove SG as shown in FIG. 2, for example. That is, the thrust dynamic pressure generating groove SG shown in FIG. 2 is formed so as to form a spiral shape on the outer peripheral side portion of the upper end surface of the bearing sleeve 13 shown in the figure. By being arranged on the outer peripheral side portion of the thrust facing region between the illustrated upper end surface and the illustrated lower end surface of the rotating hub 22, it exists in the entire thrust facing region including the thrust dynamic pressure bearing portion SB. The pumping means for pressurizing the lubricating fluid that is inwardly inward in the radial direction is also used.

  Returning to FIG. 1 again, a fluid seal portion CS is defined on the outermost wall surface of the bearing sleeve 13 as the dynamic pressure bearing member. The fluid seal portion CS has a composite seal function that pushes the lubricating fluid toward the inner side of the bearing space by using both the capillary force and the rotational centrifugal force of the lubricating fluid. The thrust facing region provided at the radially outer end portion of the bearing space including the pressure bearing portion SB is connected so as to communicate from the radially outer side.

  The fluid seal portion CS is between the outer peripheral wall surface of the bearing sleeve 13 and the inner peripheral wall surface of the retaining counter plate 25 disposed so as to face the outer peripheral wall surface of the bearing sleeve 13 in the radial direction. It is defined. Among them, the retaining counter plate 25 is formed of an annular member fixed by the flange portion 22e provided on the rotary hub 22 described above, and includes the inner peripheral wall surface of the retaining counter plate 25 and the bearing described above. A gap between the outer peripheral wall surface of the sleeve 13 is continuously enlarged toward the opening on the lower side in the figure, so that the fluid seal portion CS is formed to form a tapered seal space. . The lubricating fluid in the thrust dynamic pressure bearing portion SB described above is continuously filled up to the fluid seal portion CS.

  On the other hand, a retaining collar 13b is provided on the outermost peripheral portion of the bearing sleeve 13 on the upper end side in the figure so as to project outward in the radial direction. A part of the retaining hook 13b is disposed so as to overlap with a part of the retaining counter plate 25 described above in the radial direction, and both the retaining members 13b, 25 are close to each other in the axial direction. Therefore, the rotation hub 22 is prevented from being detached in the axial direction by being disposed so as to face each other.

  At this time, a narrow gap passage S1 is formed in the axially facing portion between the both retaining members 13b, 25 described above, and the retaining collar portion 13b described above and the rotating hub 22 are shown below. A narrow gap passage S2 is also formed in the thrust facing region between the end faces. That is, both the retaining members 13b and 25 are provided at the outer end portion of the bearing space including the above-described two radial dynamic pressure bearing portions RB and RB and the thrust dynamic pressure bearing portion SB, that is, the thrust dynamic pressure bearing portion SB. In the communication connection portion from the outermost peripheral portion to the fluid seal portion CS, the narrow gap passages S1, S2 are arranged.

  Furthermore, a fluid injection passage S3 that substantially enlarges the passage area of the narrow gap passages S1 and S2 described above is provided on at least one side of the retaining members 13b and 25. As shown in FIG. 2 in particular, the fluid injection passage S3 in the present embodiment is formed by cutting out the outer peripheral edge portion of the retaining collar 13b in a substantially arc shape in a part in the circumferential direction. In this case, the passage area in a part of the circumferential direction of each of the narrow gap passages S1 and S2 described above is enlarged by an amount corresponding to the cutout of the fluid injection passage S3. It becomes.

  As described above, in the hydrodynamic bearing device according to the present embodiment having a so-called single thrust structure, fluid is applied to the narrow gap passages S1 and S2 formed in the facing gap between the both retaining members 13b and 25 described above. Although the injection passage S3 is provided, the passage areas of both the narrow gap passages S1 and S2 are expanded, and the flow resistance of the lubricating fluid in the lubricating fluid injection passage leading to the bearing space is reduced. The As a result, the lubricating fluid injected from the fluid seal portion CS using the following injection device quickly passes through the fluid injection passage S3 described above in addition to the narrow gap passages S1 and S2, and It is designed to quickly flow toward the interior of the bearing space.

  The injection of the lubricating fluid into the bearing space is performed using, for example, an injection device as shown in FIG. That is, as shown in the figure, after forming the bearing set AB in which the bearing sleeve 13 is mounted on the rotor set 20 described above, a seal ring is formed against the fluid seal portion CS in the bearing set AB. The injection jig 32 is connected in an airtight manner via 31. A fluid supply passage 32a is provided at a substantially central portion of the injection jig 32 so as to extend downward in the figure and open to the outside.

  First, through the fluid supply passage 32a of the injection jig 32, the air in the bearing space in the above-described bearing set AB is extracted by using a vacuum pump or the like, so that the inside of the bearing space is almost in a vacuum state. Next, the lower end side opening of the fluid supply passage 32a provided in the injection jig 32 is immersed in the lubricating fluid DF stored in an appropriate amount in an appropriate container, and then the bearing space described above. The lubricating fluid DF is sucked inward by the negative pressure inside. The lubricating fluid DF sucked up through the fluid supply passage 32a is, from the above-described fluid seal portion CS, both narrow gap passages S1 and S2 formed between the both retaining members 13b and 25, and both narrow gaps thereof. The fluid flows into the bearing space through the fluid injection passage S3 attached to the passages S1 and S2.

  On the other hand, in each of the embodiments shown in FIGS. 4 and 5, a structure in which the outer peripheral edge portion of the retaining collar 13b is cut out in a substantially U shape in a part in the circumferential direction is employed. However, in the embodiment according to FIG. 4, only one fluid injection passage S4 having a relatively large opening area is provided, whereas in the embodiment according to FIG. 5, a relatively small opening is provided. A plurality of (three) fluid injection passages S5 having an area are provided at substantially equal intervals in the circumferential direction.

  Furthermore, in the embodiment shown in FIG. 6, fluid injection passages S <b> 6 made of axial through holes are provided at substantially equal intervals in the circumferential direction (6 The two narrow gap passages S1 and S2 described above are in communication with each other by the fluid injection passages S6, and thereby the two narrow gap passages S1 and S2 are connected to each other. The passage area is enlarged. Also in each of such embodiments, the same operation and effect as the above-described embodiment can be obtained.

  On the other hand, the present invention can be similarly applied to a so-called conical conical hydrodynamic bearing device as shown in FIG. The same components as those in the above-described embodiment will be denoted by the same reference numerals and detailed description thereof will be omitted, and configurations different from those in the embodiment according to FIG. 1 will be described below.

  A shaft bush 71 serving as a shaft member constituting a part of the rotor set 20 is rotatable around the rotation center axis X in the bearing center hole 73a of the bearing sleeve 73 serving as a hydrodynamic bearing member. Has been inserted. The shaft bush 71 in the present embodiment is formed of stainless steel having a substantially conical shape corresponding to the bearing center hole 73a of the bearing sleeve 73 described above. A substantially conical inclined dynamic pressure surface is formed on the inner peripheral surface of the bearing center hole 73a in the bearing sleeve 73, and the substantially conical inclined motion is also formed on the outer peripheral surface of the shaft bush 71. Each pressure surface is formed. In addition, on the inclined dynamic pressure surface of the bearing sleeve 73, an annular recess as an oil reservoir is recessed so as to form a belt shape at a substantially central portion.

  Further, an inclined bearing space consisting of a minute gap is formed in the facing portion between the both inclined dynamic pressure surfaces described above, and the two conical dynamic pressure bearing portions CB and CB are inclined dynamic pressure surfaces in the inclined bearing space. They are formed at an appropriate interval along the direction. More specifically, the inclined dynamic pressure surface on the bearing sleeve 73 side and the inclined dynamic pressure surface on the shaft bush 71 side constituting the respective conical dynamic pressure bearing portions CB form an inclined bearing space having a gap of several μm. The bearing space including the inclined bearing space is continuously filled with a lubricating fluid such as an ester-based or poly-α-olefin-based lubricating oil.

  At this time, the opening provided at the lower end of the bearing sleeve 73 in the figure is closed by a cover 73b, and the cover 73b prevents the lubricating fluid in each of the above-mentioned conical dynamic pressure bearing portions from leaking to the outside. ing.

  Further, on at least one side of both the inclined dynamic pressure surfaces of the bearing sleeve 73 and the shaft bush 71, a dynamic pressure generating means having a herringbone-shaped concave groove structure (not shown) is provided along the direction of the inclined dynamic pressure surface. When the shaft bush 71 is rotationally driven, the lubricating fluid is pressurized by the pumping action of each of the dynamic pressure generating grooves to generate a dynamic pressure. The shaft bush 71 is lifted relative to the bearing sleeve 73 in the radial direction and the thrust direction by pressure, and is held in a non-contact state, thereby being formed integrally with the shaft bush 71 and the shaft bush 71, or The rotating hub body 22 fixed integrally is configured to be rotatably supported.

  The lubricating fluid pressurized by the dynamic pressure generating groove in this way flows out to the external space from one side end opening at both axial end portions of the inclined bearing space including the conical dynamic pressure bearing portions CB. However, the lubricating fluid that has flowed into the external space passes through the circulation hole 73c provided so as to penetrate the body portion of the bearing sleeve 73 in an inclined state, and the original conical motion described above from the other side end opening. It is made the structure returned in the pressure bearing part CB.

  Furthermore, as particularly shown in FIG. 8, the upper end surface of the bearing sleeve 73 shown in the drawing and the rotating hub 22 extending to the outer peripheral side of the large-diameter portion on the base side of the shaft bush 71 described above. The lower end surface shown in the figure is arranged so as to face the axially close state, and the inclined bearing space described above is interposed between the upper end surface shown in the drawing of the bearing sleeve 73 and the lower end surface of the rotary hub 22 in the drawing. An axially facing gap AS continuous from the opening at the upper end in the drawing, that is, the outer peripheral side, is formed so as to extend along a radial direction substantially orthogonal to the rotation axis X. In addition, a radial clearance RS that is bent substantially at a right angle downward in the drawing and extends in the axial direction is formed in the end opening on the outer peripheral side of the axial facing clearance AS.

  The radial clearance RS includes an outer peripheral surface of a retaining latch 73d projecting so as to form a flange at the outermost peripheral portion of the upper end portion of the bearing sleeve 73 and a retaining latch 73d. Is formed by bringing the lower end surface of the center side of the rotating hub 22 close to the inner peripheral surface of the annular base portion 22f protruding substantially downward in the radial direction so as to cover from the outer peripheral side in the radial direction. ing. A composite fluid seal portion CS using both capillary force and rotational centrifugal force is connected to the end opening on the lower end side of the radial gap RS in the drawing so as to extend downward in the drawing. ing.

  The inner peripheral side inclined wall surface and the outer peripheral side inclined wall surface of the composite fluid seal portion CS are the outer peripheral side surface of the bearing sleeve 73 described above, and a retaining ring that is arranged to face the bearing sleeve 73 radially outward. The material 75 is formed by the inner peripheral surface. The retaining ring material 75 is formed from an annular member formed in a substantially ring shape, and the plate-shaped hub mounting portion 75a forming the outer peripheral side portion of the retaining ring material 75 is described above. It is fixed by a fixing portion 22e provided on the rotating hub 22.

  Further, as described above, a part of the retaining locking collar portion 73d of the bearing sleeve 73 is disposed so as to face the upper surface side of the main body portion 75b of the retaining annular member 75 in the axial direction. ing. The two retaining members 73d and 75b are arranged so as to be capable of contacting in the axial direction, thereby preventing the rotary hub 22 from slipping out in the axial direction.

  Here, a narrow gap passage S7 is formed in the axially opposite portion between the both retaining members 73d and 75b described above, and the retaining collar 73d described above and the rotating hub 22 are illustrated below. The axial facing gap AS described above is also provided in the thrust facing area between the end faces so as to form a narrow gap passage. That is, the both retaining members 73d and 75b communicate from the outer end portion on the upper end side of the bearing space including the two conical dynamic pressure bearing portions CB and CB described above to the fluid seal portion CS. In the connection portion, the narrow gap passages S7 and AS are arranged to form an arrangement relationship.

  Furthermore, a fluid injection passage S8 that substantially enlarges the passage area of the narrow gap passages S7 and AS described above is provided on at least one side of the both retaining members 73d and 75b. The fluid injection passage S8 itself has the same structure as that of the above-described embodiment (see FIGS. 2, 4, 5, and 6).・ Effects can be obtained.

  Furthermore, the spindle motor in each of such embodiments is used by being mounted inside a hard disk drive (HDD) as shown in FIG. 9, for example, and similar operations and effects can be obtained.

  That is, as shown in FIG. 9, the spindle motor M provided with the hydrodynamic bearing device according to each of the above-described embodiments is fixed to the main body plate 100 a constituting the hermetic housing 100. The internal space of the housing 100 used and including the spindle motor M is formed in the clean space 100c by the sealing lid 100b fitted to the main body plate 100a. An information recording disk 101 such as a hard disk is mounted on a rotating hub body (see reference numeral 22 in FIG. 1) of the spindle motor M, and a clamp 103 fixed to the rotating hub by a screw 102, The information recording disk 101 is held in an immobile state.

  As mentioned above, the invention made by the present inventor has been specifically described based on the embodiments. However, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the scope of the invention. Needless to say.

  For example, in each of the above-described embodiments, the present invention is applied to a shaft rotation type spindle motor. However, the present invention can be similarly applied to a shaft fixed type spindle motor. is there.

  Further, in each of the above-described embodiments, the present invention is applied to a spindle motor for a hard disk drive (HDD), but the present invention is similarly applied to various other dynamic pressure bearing devices. It can be applied.

  The present invention described above can be widely applied to a hydrodynamic bearing device used in various types of rotary drive devices including various motors.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinal cross-sectional explanatory view showing an outline of a shaft rotation type HDD spindle motor provided with a hydrodynamic bearing device to which the present invention is applied. FIG. 2 is an enlarged plan view illustrating an upper end surface portion of a bearing sleeve used in the HDD spindle motor illustrated in FIG. 1. FIG. 2 is a longitudinal sectional explanatory view showing a schematic structure of a lubricating fluid injection jig for a hydrodynamic bearing device used in the HDD spindle motor shown in FIG. 1. It is plane explanatory drawing which expanded and represented the upper end surface part of the bearing sleeve concerning other embodiment of this invention. FIG. 10 is an enlarged plan view illustrating an upper end surface portion of a bearing sleeve according to still another embodiment of the present invention. FIG. 10 is an enlarged plan view illustrating an upper end surface portion of a bearing sleeve according to still another embodiment of the present invention. It is longitudinal cross-sectional explanatory drawing showing the outline | summary of the spindle motor for shaft rotation type HDD provided with the hydrodynamic bearing apparatus of the other type to which this invention is applied. FIG. 8 is a longitudinal cross-sectional explanatory view showing an enlarged structure of a bearing portion used in the HDD spindle motor shown in FIG. 7. 1 is a longitudinal cross-sectional explanatory view showing a schematic structural example of a disk drive device using a spindle motor provided with a hydrodynamic bearing device according to the present invention. It is a longitudinal cross-sectional explanatory drawing showing an example of the hydrodynamic bearing apparatus developed conventionally.

Explanation of symbols

13 Bearing sleeve (bearing member)
13b Retaining collar 21 Rotating shaft (shaft member)
22 Rotating hub (Rotating member)
25 Retaining counter plate RB Radial dynamic pressure bearing portion SB Thrust dynamic pressure bearing portion SG Thrust dynamic pressure generating groove S1, S2 Narrow gap passage S3 Fluid injection passage CS Fluid seal portion AB Bearing assembly 31 Seal ring 32 Injection jig 32a Fluid supply Passage DF Lubricating fluid S4, S5, S6 Fluid injection passage 71 Shaft bushing 73 Bearing sleeve 73d Retaining latching collar 75 Retaining ring material CB Conical dynamic pressure bearing S7, AS Narrow gap passage S8 Fluid injection passage M Spindle motor 100 Housing 101 Information recording disk

Claims (4)

An appropriate lubricating fluid is continuously filled in a bearing space formed by the fixed member and the rotating member being arranged close to each other and facing each other,
A dynamic pressure bearing portion that generates dynamic pressure in the lubricating fluid and supports the fixed member and the rotating member in a non-contact manner is provided over a plurality of locations in the bearing space,
A fluid seal portion for preventing external leakage of the lubricating fluid is connected to an outer end portion of the continuous bearing space including the plurality of hydrodynamic bearing portions, and from the outer end portion of the bearing space. In the communication connection portion that reaches the fluid seal portion, both the retaining members provided on the fixed member side and the rotating member side are arranged opposite to each other in the axial direction, so that the axial direction of the rotating member It is configured with a retaining mechanism for preventing separation,
In the hydrodynamic bearing device in which a narrow gap passage is formed between the both retaining members on the fixed member side and the rotating member side,
A fluid injection passage that substantially enlarges the passage area of the narrow gap passage is provided on at least one side of both retaining members provided on the fixed member side and the rotating member side, respectively. Hydrodynamic bearing device. While either one of the fixed member and the rotating member includes a bearing member,
The other side of the fixed member and the rotating member includes a shaft member inserted into the inner side of the bearing member so as to be relatively rotatable,
2. The hydrodynamic bearing device according to claim 1, wherein the retaining member is provided for each of the bearing member and the shaft member, or a member integrally joined to the both members. The narrow gap passage formed between the two retaining members is a radially outer end of a thrust dynamic pressure bearing portion formed by the fixed member and the rotating member being disposed close to each other in the axial direction. Provided in a portion adjacent to the radially outward side of the portion,
2. The hydrodynamic bearing device according to claim 1, wherein the fluid injection passage is attached to the narrow gap passage. A spindle motor comprising the hydrodynamic bearing device according to any one of claims 1 to 3, an information recording disk mounted on a rotor of the spindle motor, and recording or reproducing information on the information recording disk And a recording head.

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