JP2009108948A - Fluid bearing device and spindle motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fluid bearing device capable of maintaining lubricating fluid 28 in a bearing gap for a longer period of time even when the lubricating fluid 28 evaporates. <P>SOLUTION: A lubricant reservoir 35 formed between a cover 26 and the end surface of a sleeve 15 on the side of an opening has a portion with cross sectional area gradually changed and a portion with cross sectional area drastically changed, when viewed from the cross sectional surface of the lubricant reservoir 35 in the circumferential direction of the sleeve 15. Thereby, the fluid bearing device 13 can maintain the lubricant 28 therein for the longer period of time. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a hydrodynamic bearing device used in a spindle motor that rotationally drives a magnetic disk, an optical disk, and the like.

  As a bearing device used for a spindle motor of a hard disk device, in place of a conventionally used ball bearing device, many hydrodynamic bearing devices that are superior in rotational accuracy and quietness are employed. Yes.

  In this hydrodynamic bearing device, when the lubricating fluid filled in the micro gap evaporates and leaks to the outside, the lubricating fluid is not interposed in the micro gap, which causes rotation failure. It becomes a fatal wound.

  Since it is difficult to suppress the evaporation of the lubricating fluid that is a liquid, various studies have been made to maintain the lubricating fluid in the hydrodynamic bearing device for a long period of time.

  For example, the conventional hydrodynamic bearing device 1 shown in FIG. FIG. 7A is a cross-sectional view of a conventional hydrodynamic bearing device 1.

  A conventional hydrodynamic bearing device 1 includes a shaft 2, a sleeve 3 disposed on the outer periphery of the shaft 2 through a gap, a thrust plate 4 closing one end of the sleeve 3, and one end of the shaft 2. A thrust flange 5 is provided at a side end portion and arranged in a posture having a gap with respect to the sleeve 3 and the thrust plate 4, and a gap between the outer peripheral surface of the shaft 2 and the inner peripheral surface of the sleeve 3 is provided. The gap between the both surfaces of the thrust flange 5 and the end surface of the sleeve 3 opposed to the thrust flange 5 and the end surface of the thrust plate 4 is filled with a lubricating fluid 6.

  A cover 7 is disposed so as to cover the end surface of the sleeve 3 on the opening side, and a fluid reservoir space 8 is formed.

  Further, a communication path 10 that connects the space 9 forming the thrust bearing portion and the fluid pool space portion 8 is formed in the sleeve 3, and the lubricating fluid 6 filled in the clearance of the bearing device can be circulated. It has a possible configuration.

  Further, the cover 7 is formed with an inclined surface 11 that is inclined radially outward from the rotation center axis of the shaft 2 on the inner peripheral surface, and between the outer peripheral surface of the shaft 2 and the lubricating fluid 6. A seal structure is formed so as not to leak to the outside, and air bubbles inside the bearing are formed in a portion located 180 degrees diagonally to the opening of the communication passage 10 on the opening side end surface of the sleeve 3. A vent hole 12 for discharging is formed.

  The fluid reservoir space portion 8 formed between the opening side end surface of the sleeve 3 and the back surface of the cover 7 is inclined so that the space becomes narrower from the vent hole 12 toward the communication hole 10. It is a space.

  Here, a state where the interface of the lubricating fluid 6 in the fluid pool space 8 moves due to evaporation or the like will be described with reference to FIG.

  Since the fluid reservoir space 8 is formed to be the narrowest in the vicinity of the communication hole 10 and the widest in the vicinity of the vent hole 12, the interface of the lubricating fluid 6 is first separated by the interface 6 a and the interface by evaporation. Move to 6aa. Next, it moves to the interface 6b and the interface 6bb. Similarly, the interface of the lubricating fluid 6 moves from the vent hole 12 toward the communication hole 10.

That is, the two interfaces of the lubricating fluid 6 held in the fluid pool space 8 are prevented from immediately moving to the bearing gap due to evaporation.
JP 2006-161988 A

  However, since the lubricating fluid 6 held in the fluid pool space 8 has two interfaces, the amount of evaporation of the lubricating fluid 6 is large, and the lubricating fluid 6 is held in the bearing gap over a long period of time. It had the problem that it was difficult.

  Accordingly, an object of the present invention is to provide a hydrodynamic bearing device that can maintain the lubricating fluid 6 in the bearing gap over a long period of time.

  In order to achieve the above object, a hydrodynamic bearing device of the present application includes a sleeve having a bearing hole having an open end and a closed end, a shaft that is rotatably inserted into the bearing hole via a gap, A cover that covers the open end side end surface of the sleeve to form a first space; a second space on the closed end surface side in the bearing hole in the sleeve; and the sleeve that communicates the first space with the second space. The formed communication passage, the lubricating fluid filled in the gap between the cover, the sleeve and the shaft, the radial bearing formed between the outer peripheral surface of the shaft and the inner peripheral surface of the sleeve, and the closure of the sleeve of the shaft A thrust bearing portion formed between the end surface on the end side and the end surface on the inner side of the closed end of the sleeve, and an introduction gap formed between the vicinity of the opening portion of the communication path and the opening end of the bearing hole in the first space Part and formed on the cover The first space and the first lubricating fluid reservoir, and the first space has a first lubricating fluid reservoir portion in which the space sectional area gradually decreases in the circumferential direction from the vent toward the opening of the communication passage. And a second lubricating fluid reservoir that has a spatial cross-sectional area that rapidly decreases in the circumferential direction.

  According to the hydrodynamic bearing device of the present invention, in two different interfaces of the lubricating fluid held in the fluid pool space formed by the cover that covers the opening side end surface of the sleeve, each of the interfaces is time-consuming due to evaporation or the like. By changing the amount of movement with the passage of time, it is possible to provide a hydrodynamic bearing device capable of maintaining the sliding fluid in the bearing gap over a long period of time.

  Embodiments of the hydrodynamic bearing device of the present invention will be described below in detail with reference to the drawings.

(Embodiment 1)
FIG. 1 is a cross-sectional view of a spindle motor 14 provided with a hydrodynamic bearing device 13 according to a first embodiment of the present invention. In addition, although the following description demonstrates for the sake of convenience as the case where the opening end in the bearing hole 15a of the sleeve 15 is arrange | positioned upwards and a closed end is arrange | positioned below, when actually using, it does not restrict to this arrangement | positioning.

  As shown in FIG. 1, a columnar protruding shaft portion 16a protruding from a circular bearing hole 15a of a cylindrical sleeve 15 in a shaft 16 is used as a rotating member to which, for example, a magnetic recording disk is fixed on the outer periphery. A substantially reverse cup-shaped hub 17 is externally fitted in a press-fit state, and a rotor magnet 19 is attached to the inner periphery of a cylindrical hanging wall formed on the outer periphery of the hub 17. A stator core 21 around which a stator coil 20 is wound is attached to the base 18 to which the hydrodynamic bearing device 13 is fixed so as to face the rotor magnet 19 in the radial direction on the inner peripheral side of the rotor magnet 19. The rotor magnet 19 and the stator core 21 constitute a rotation drive unit 22 of the spindle motor 14 that applies a rotation drive force between the shaft 16 and the sleeve 15.

  Next, the hydrodynamic bearing device 13 will be described with reference to FIG. FIG. 2 is a cross-sectional view of the hydrodynamic bearing device 13. The hydrodynamic bearing device 13 includes a shaft 16, a sleeve 15, a thrust flange 23, a thrust plate 24, and a cover 26. The sleeve 15 is fixed to the base 18 of the spindle motor 14 as shown in FIG. As shown, the sleeve 15 has a bearing hole 15a having an upper opening end 15aa which is opened and a lower closing end 15ab which is closed, and a cylindrical shaft 16 is inserted in a rotatable posture through a gap. ing.

  The thrust flange 23 has a disk shape larger in diameter than the shaft 16, is fixed to the lower end portion of the shaft 16 by external fitting or a screw, and is a large-diameter hole on the closed end side of the bearing hole 15a. The portion 15ac is disposed in a posture having a gap with respect to the upper surface of the large-diameter hole portion 15ac.

  The thrust plate 24 has a disk shape larger than the bearing hole 15a of the sleeve 15, and is fixed to the bottom of the sleeve 15 so as to face the lower surface of the thrust flange 23 with a gap.

  Furthermore, the cover 26 has a circular hole that is fitted with a gap with the shaft 16, and an inclined surface that extends radially outward from the rotation center axis of the shaft 16 is formed on the inner peripheral surface thereof, While covering the upper end surface (opening end side end surface) of the sleeve 15 in a state having a space, the sleeve 15 has one air vent 25 communicating the space with the outside air. In addition, the material of the cover 26 is comprised with the material which has translucency in order to make it easy to confirm the interface of the lubricating fluid 28 when lubricating the lubricating fluid 28 mentioned later.

  In the hydrodynamic bearing device 13, one communicating hole 27 (for example, the diameter is about 0.2 mm to 0.6 mm) is drilled at a location near the outer peripheral surface of the sleeve 15 in parallel with the rotation center axis. The communication hole 27 allows a large-diameter hole 15ac (space region on the closed end surface side) provided on the closed end 15ab side of the bearing hole 15a, and an upper end surface that is an end surface on the open end 15aa side of the cover 26 and the sleeve 15 to be opened. And a spatial area between the two.

  Further, the space inside the sleeve 15 including the space between the cover 26 and the sleeve 15 (that is, the space between the outer peripheral surface of the shaft 16 and the inner peripheral surface of the sleeve 15, the large-diameter hole portion 15ac of the bearing hole 15a). A space, a space at a communication portion between the large-diameter hole portion 15ac of the bearing hole 15a and the communication hole 27, a space in the communication hole 27, and a space between the upper end surface of the sleeve 15 and the cover 26 (however, a vent hole). 25 places are excluded.))) Is filled with the lubricating fluid 28.

  Then, the inner surface of the sleeve 15 (or the outer surface of the shaft 16 or both the inner surface of the sleeve 15 and the outer surface of the shaft 16) may be provided with a dynamic pressure such as a herringbone shape vertically. Grooves 29 and 30 are formed, and when the shaft 16 and the sleeve 15 are relatively rotated by the rotational driving force described above, the shaft 16 is driven by the force of the lubricating fluid 28 scraped by the dynamic pressure grooves 29 and 30. A radial dynamic pressure bearing 31 is configured in which the sleeve 15 and the sleeve 15 are rotatably supported via a predetermined gap in the radial direction (radial direction).

  Further, the upper surface and the lower surface of the thrust flange 23 (or the lower surface of the sleeve 15 and the upper surface of the thrust plate 24 facing each other, or the upper and lower surfaces of the thrust flange 23 and the lower surface of the sleeve 15 and the upper surface of the thrust plate 24 are provided. The dynamic pressure grooves 32 and 33 having a spiral shape or the like are formed on the shaft 16 and the thrust flange 23 attached to the shaft 16 and the sleeve 15 are relatively rotated by the rotational driving force described above. Due to the force of the lubricating fluid 28 scraped out by the dynamic pressure grooves 32 and 33, a thrust dynamic pressure bearing 34 is supported in which the shaft 16 and the sleeve 15 are rotatably supported via a predetermined gap in the thrust direction (axial direction). It is configured.

  Here, the dynamic pressure grooves 29 and 30 constituting the radial dynamic pressure bearing 31 have a well-known herringbone shape and are formed at two locations on the upper and lower sides of the outer peripheral surface of the shaft 16. In the dynamic pressure groove 30, a groove that rises obliquely from the top and a groove that falls obliquely have the same length, while the upper dynamic pressure groove 29 has a groove 29a that rises obliquely from the top, obliquely from the top. It is formed longer than the lowering groove 29b, and is configured so that the working fluid 28 in this gap is actively sent downward by the upper dynamic pressure groove 29 during rotational driving.

  In the hydrodynamic bearing device 13 configured as described above, a space formed by the upper end surface of the sleeve 15 on the opening end 15aa side and the cover 26 and filled with the lubricating fluid 28 (hereinafter referred to as a lubricating fluid reservoir 35). ) Plays a role of storing the lubricant against the decrease of the lubricating fluid 28 due to evaporation or the like. The configuration will be described below with reference to FIG.

  FIG. 3A is a view of the lubricating fluid reservoir 35 as viewed from the open end 15aa side of the sleeve 15. FIG. 3B is a schematic view in which the lubricating fluid reservoir 35 is developed.

  As shown in FIGS. 3A and 3B, the upper end surface 15e of the sleeve 15 facing the cover 26 has a substantially planar shape. The shape of the back surface portion of the cover 26 facing the upper end surface 15e is such that the introduction gap portion 27a in the vicinity of the opening portion of the communication hole 27 opening in the upper end surface 15e of the sleeve 15 and the outer periphery in the vicinity of the opening end of the bearing hole 15a in the sleeve 15 In the region 15ad, the distance from the upper end surface 15e of the sleeve 15 is such that a capillary phenomenon occurs, and the lubricating fluid 28 flows into the bearing hole 15a on the inner peripheral surface of the sleeve 15 by the capillary phenomenon. . The introduction gap 27a is formed so as to continue to the opening end of the bearing hole 15a of the sleeve 15 via the region 15ad.

  Here, in the introduction gap portion 27a and the region 15ad, the separation gap formed between the back surface portion of the cover 26 and the upper end surface 15e of the sleeve 15 is, for example, 0.03 mm to 0.15 mm. Is constant in the radial direction.

  Further, the shape of the back surface portion of the cover 26 is formed between the back surface portion of the cover 26 and the upper end surface 15e of the sleeve 15 in the introduction gap portion 27a and the region 15ad in places other than the introduction gap portion 27a and the region 15ad. A lubricating fluid reservoir 35 that can store the lubricating fluid 28 is formed by being recessed so as to be a larger space than the separation gap, and the lubricating fluid reservoir 35 connects the introduction gap 27a and the vent hole 25 in the circumferential direction. Communicate.

  Here, the fluid reservoir space 35 has, for example, an inner diameter of 3.2 mm to 3.8 mm, an outer diameter of 5.5 to 6.3 mm, a minimum gap of 0.03 mm to 0.15 mm, and a maximum gap of 0.2 mm to It is about 0.3 mm.

  The vent hole 25 has a diameter of, for example, about 0.2 mm to 1.0 mm. The back surface of the cover 26 has a concentric circle around the vent hole 25 and a larger diameter than the vent hole 25. A recess 36 (for example, a diameter of about 0.6 mm to 1.0 mm and a depth of about 0.1 mm to 0.3 mm) is formed as a buffer space formed by a counterbore.

  The fluid reservoir space 35 connected to the vent hole 25 and the recess 36 (referred to as the maximum space 35a) has the largest separation distance from the upper end surface 15e of the sleeve 15, and the fluid reservoir space 35 is the introduction gap. The rear surface of the bar 26 that forms the fluid pool space 35 is inclined with respect to the circumferential direction so that the distance from the upper end surface 15e (opening end side end surface) of the sleeve 15 increases as the distance from 27a approaches the maximum space 35a. It is formed in the shape to do.

In the present embodiment, the clearance gap of the fluid reservoir space 35 is constant in the radial direction, and the vent hole 25 communicating with the outside air is an opening of the communication passage 27 in the cover 26 in plan view. Is provided at an angle of about 15 degrees. However, it is not limited to this,
As long as the configuration of the cover 26 is possible, it goes without saying that the smaller the angle, the longer the circumferential distance of the fluid reservoir space 35, and the longer it is possible to maintain the lubricating fluid in the bearing gap for a longer period.

  Further, since the recess 36 is formed in the vent hole 25, even when the temperature of the installation environment of the hydrodynamic bearing device 13 is increased in a state where the lubricating fluid 28 is full, the interface K 2 of the lubricating fluid 28 becomes the recess 36. It is intended that the lubricating fluid 28 stays inside and does not leak from the vent hole 25 to the outside.

  Here, the change of the interface accompanying the evaporation of the lubricating fluid 28 in the lubricating fluid reservoir 35 configured as described above will be described with reference to FIG. 4A illustrates a state before the lubricating fluid 28 in the lubricating fluid reservoir 35 evaporates, and FIG. 4B illustrates a state in which the lubricating fluid 28 in the lubricating fluid reservoir 35 has been evaporated by half. FIG. 4C illustrates a state in which the lubricating fluid 28 in the lubricating fluid reservoir 35 has almost evaporated.

  When the lubricating fluid 28 evaporates from the state of FIG. 4A, the interface of the lubricating fluid 28 located in the vent hole 25 moves, and the interface moves in the left-right direction of the lubricating fluid reservoir 35 in FIG. 4A. To do. However, the space 35b formed between the vent hole 25 and the communication hole 27 is a cross-sectional area of the interface in the lubricating fluid reservoir 35 due to the inclined surface formed on the back surface portion of the cover 26 (FIG. ), The sectional area of the lubricating fluid reservoir 35 when the lubricating fluid reservoir 35 is viewed from the circumferential direction is referred to as a spatial sectional area). On the other hand, the other space 35c is formed such that the cross-sectional area of the interface in the lubricating fluid reservoir 35 gradually changes.

  Here, since the evaporation of the lubricating fluid 28 is affected by the cross-sectional area of the interface, as described above, the lubricating fluid reservoir 35 has a space 35b in which the cross-sectional area changes rapidly and a space 35c in which the cross-sectional area changes gently. Existing. Therefore, as shown in FIG. 4B, the amount of movement of the interface 28a, 28b of the lubricating fluid 28 increases on the space 35c side.

  Then, as shown in FIG. 4C, when the lubricating fluid 28 in the lubricating fluid reservoir 35 is completely evaporated, the introduction gap 27a in the vicinity of the opening of the communication hole 27 and the sleeve 15 are shown in FIG. The lubricating fluid 28 remains in the region 15ad on the outer periphery in the vicinity of the opening end of the bearing hole 15a.

  As described above, the interface moves due to the evaporation of the lubricating fluid 28. Further, the point where the interface moves in the left-right direction in the lubricating fluid reservoir 35 will be described with reference to FIG.

  FIG. 5 shows an interface between the lubricating fluid 28 (the lubricating fluid 28 and the atmosphere are formed in the fluid reservoir space 35 formed by the upper end surface 15e of the sleeve 15 and the cover 26 disposed opposite to the upper end surface 15e. The state of the contact surface) is simply illustrated.

The fluid reservoir space 35 is filled with the lubricating fluid 28 by a well-known technique such as a vacuum lubrication method, but the lubricating fluid 28 evaporates as time passes. As a result, the surface tension of the lubricating fluid 28, the surface area of the interface that is in contact with the atmosphere, and the atmospheric pressure P are balanced, and the interface 28a and interface 28b are in the state shown in FIG. This balanced state will be described.
In the lubricating fluid reservoir 35, the surface tension F1 of the lubricating fluid 28 is acting on the interface 28a from the lubricating fluid 28 toward the atmospheric pressure P. The surface tension F1 and the atmospheric pressure P in the lubricating fluid reservoir 35 are balanced and satisfy (Equation 1). Similarly, the surface tension F2 also acts on the interface 28b and is balanced with the atmospheric pressure P in the lubricating fluid reservoir 35, and satisfies (Expression 2).

F1 / Aa = Pa (Formula 1)
F2 / Ab = Pb (Formula 2)
Pa = Pb = P (Formula 3)
Aa: Surface area in contact with the atmosphere at the interface 28a Ab: Surface area in contact with the atmosphere at the interface 28b That is, from the above equation (3), the lubricating fluid is balanced in the state of the interfaces 28a and 28b shown in FIG. 28 is prevented from leaking outside.

  Next, the state of the interface when the lubricating fluid 28 evaporates from this state will be described. First, the interface 28a will be described. As the lubricating fluid 28 evaporates, the interface 28a moves to the interface 28aa as shown in FIG. The relationship among the surface tension F3 at the interface 28aa, the surface area in contact with the atmosphere at the interface, and the atmospheric pressure P in the lubricating fluid reservoir 35 satisfies the equation (4). Similarly, the interface 28b moves to the interface 28bb, and the relationship between the surface tension F4 at the interface 28bb, the surface area in contact with the air at the interface, and the atmospheric pressure P in the lubricating fluid reservoir 35 is expressed by the equation (5). ) Is satisfied.

F3 / Aaa = Paa (Formula 4)
F4 / Abb = Pbb (Formula 5)
Paa = Pbb = P (Formula 6)
Aaa: Surface area in contact with the atmosphere at the interface 28aa Abb: Surface area in contact with the atmosphere at the interface 28bb In other words, the interface of the lubricating fluid 28 is always large as shown in the equations (3) and (4). The interface is moved while maintaining a state in balance with the atmospheric pressure P.

However, the interface 28b and the interface 28bb have almost the same surface area where the interface is in contact with the atmosphere, and the surface area where the interface is in contact with the atmosphere is small compared to the interface 28a (28aa).
Ab≈Abb
And as a result,
F2 / Ab ≒ F4 / Abb
It becomes. That is, the interface 28b is almost at the same position even if the lubricating fluid 28 evaporates.

  As described above, as the lubricating fluid 28 evaporates, the interface moves in one direction (the direction from the interface 28a toward the communication hole 27 in FIG. 5).

  In the present embodiment, in order to satisfy the above-described relationship, an inclined surface with an inclination angle of 5 degrees is provided on the back surface portion of the cover 26 forming the interface 28a, and the interface 28b is formed. An inclined surface with an inclination angle of 50 degrees is provided on the back surface of the cover 26.

  As for the inclination angle of the inclined surface provided on the back surface portion of the cover 26 forming these two interfaces (28a, 28b), as long as the ratio of the inclination angles is twice or more, as described above, it is unidirectional. Will move toward. In addition, preferably, the effect can be further induced by setting it to 10 times or more.

  As described above, according to the present embodiment, since the circumferential distance of the lubricating fluid reservoir 35 formed by the cover 26 and the upper end surface of the sleeve 15e can be increased, the lubricating fluid 28 is maintained for a longer period of time. Is possible.

  As mentioned above, although Embodiment 1 of this invention was demonstrated, this invention is not limited to the said embodiment, A various change is possible in the range which does not deviate from the summary of invention.

  For example, as shown in FIG. 6A and FIG. 6B, the blocking member 40 is provided with a space 35 b formed so that the circumferential cross-sectional area of the lubricating fluid reservoir 35 changes rapidly. It may be blocked at. By sealing the space 35b with the blocking member 40, the interface of the lubricating fluid 28 in the lubricating fluid reservoir 35 moves only in a limited circumferential direction, and the lubricating fluid 28 is allowed to flow for a longer period of time. It is possible to maintain. The blocking member 40 may be a separate body from the cover 26 and the sleeve 15 or may be formed integrally with either one.

  The hydrodynamic bearing device of the present invention can provide a hydrodynamic bearing device capable of maintaining the lubricating fluid in the bearing gap over a long period of time, and is mounted on a disk drive device, a reel drive device, a capstan drive device, a drum drive device, or the like. However, the present invention is not limited to this.

Sectional drawing of the spindle motor in Embodiment 1 of this invention Sectional drawing of the hydrodynamic bearing apparatus in Embodiment 1 of this invention (A), (b) is the top view which looked at the lubricating fluid reservoir in Embodiment 1 of this invention from the cover side, and the expanded view of a lubricating fluid reservoir (A), (b), (c) is a figure which shows the state of the lubricating fluid of the lubricating fluid reservoir part in Embodiment 1 of this invention. Sectional drawing of the interface of the lubricating fluid in the lubricating fluid reservoir in Embodiment 1 of this invention (A), (b) is the top view which looked at the lubricating fluid pool part in other embodiment from the cover side, and the expanded view of a lubricating fluid pool part (A), (b) is sectional drawing of the conventional hydrodynamic bearing device, and the top view which looked at the lubricating fluid reservoir from the cover side

Explanation of symbols

DESCRIPTION OF SYMBOLS 13 Fluid dynamic bearing apparatus 14 Spindle motor 15 Sleeve 15a Bearing hole 15aa Open end 15ab Closed end 15ac Large diameter hole part 15ad Area | region 16 Shaft 16a Protruding shaft part 17 Hub 18 Base 19 Rotor magnet 20 Stator coil 21 Stator core 22 Rotation drive part 23 Thrust flange 24 Thrust plate 25 Ventilation hole 26 Cover 27 Communication hole 27a Introduction gap 28 Lubricating fluid 31 Radial dynamic pressure bearing 34 Thrust dynamic pressure bearing 35 Lubricating fluid reservoir 35a Maximum space 35b, 35c Space 36 Recess

Claims (4)

A sleeve having a bearing hole having an open end and a closed end;
A shaft inserted into the bearing hole in a freely rotatable state through a gap;
A cover that covers the opening end side end surface of the sleeve and forms a first space;
A second space on the closed end face side in the bearing hole in the sleeve;
A communication path formed in the sleeve for communicating the first space and the second space;
A lubricating fluid filled in a gap between the cover, the sleeve, and the shaft;
A radial bearing portion formed between the outer peripheral surface of the shaft and the inner peripheral surface of the sleeve;
A thrust bearing portion formed between an end surface on the closed end side of the sleeve of the shaft and an end surface inside the closed end of the sleeve;
In the first space, an introduction gap formed between the vicinity of the opening of the communication passage and the opening end of the bearing hole;
A vent hole communicating the first space and the outside air formed in the cover;
The first space has a first lubricating fluid reservoir portion in which the spatial cross-sectional area gradually decreases in the circumferential direction from the vent hole toward the opening of the communication path, and the spatial cross-sectional area in the circumferential direction decreases rapidly. And a second lubricating fluid reservoir.   The first lubricating fluid reservoir and the second lubricating fluid reservoir are formed by inclined surfaces provided on the cover, and the inclined surfaces forming the first lubricating fluid reservoir are on the opening side of the sleeve. The inclination angle is 5 to 7 degrees with respect to the end face, and the inclination face forming the second lubricating fluid reservoir is an inclination angle of 50 to 70 degrees with respect to the opening-side end face of the sleeve. The hydrodynamic bearing device according to claim 1.   2. The blocking portion for blocking the flow of the lubricating fluid in the circumferential direction is formed in the second lubricating fluid reservoir portion in the vicinity of the opening portion of the communication path from the vent hole. Fluid bearing device. A spindle motor comprising the hydrodynamic bearing device according to any one of claims 1 to 3.

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