JP2010043654A - Fluid bearing device, spindle motor having the same and information processor - Google Patents

Abstract

A hydrodynamic bearing device capable of sufficiently securing the axial length of a radial bearing portion while efficiently discharging bubbles contained in a lubricating fluid to the outside air.
In a hydrodynamic bearing device, a sleeve has a substantially annular first fluid reservoir portion for containing a lubricating fluid contained therein. The first fluid reservoir 27 intersects with the communication hole 11 b in the sleeve 11 in a state where a part thereof communicates, and communicates with the outside air through the ventilation path 28.
[Selection] Figure 2

Description

  The present invention relates to a hydrodynamic bearing device mounted on a hard disk drive or the like, a spindle motor including the same, and an information processing device.

  In recent years, spindle motors mounted on disk drive devices such as hard disk drive devices (hereinafter referred to as HDDs) have developed hydrodynamic bearings (hereinafter referred to as fluid) that can achieve low NRRO (Non-Repetitive Run Out) and low noise by non-contact rotation. It is shown as a bearing device).

  In such a hydrodynamic bearing device, in order to improve the angular rigidity of the hydrodynamic bearing device, it is desirable to employ a configuration in which the length of the radial bearing portion formed in the gap between the shaft and the sleeve is secured as long as possible. . On the other hand, since there is a demand for thinning of the spindle motor, there is a need for a configuration that does not increase the thickness of the hydrodynamic bearing device while sufficiently securing the length of the radial bearing portion.

For example, Patent Document 1 has a configuration in which a cover member is attached so as to cover the end surface on the open end side of the sleeve, and a tapered seal portion is provided in a gap between the inner peripheral surface of the cover member and the outer peripheral surface of the shaft. It is disclosed. In this configuration, it is included in the lubricating fluid that circulates in the hydrodynamic bearing device from the taper seal portion disposed at a position close to the radial bearing portion formed in the gap between the outer peripheral surface of the shaft and the inner peripheral surface of the sleeve. Can be effectively discharged into the outside air.
JP 2006-161988 A (released on June 22, 2006) JP 2006-162029 A (released on June 22, 2006) JP 2006-17153 A (published on January 19, 2006) JP 2001-271838 A (released on October 5, 2001)

However, the conventional hydrodynamic bearing device has the following problems.
That is, in the hydrodynamic bearing device disclosed in the above publication, the taper seal portion is arranged so as to be aligned in the axial direction with respect to the radial bearing portion formed between the outer peripheral surface of the shaft and the inner peripheral surface of the sleeve. ing. For this reason, although the bubbles contained in the lubricating fluid can be efficiently discharged to the outside air, a part of the outer peripheral surface on the open end side of the sleeve in the shaft is occupied by the taper seal portion. In the configuration corresponding to the reduction in thickness, there is a possibility that the axial length of the radial bearing portion cannot be sufficiently secured.

  An object of the present invention is to provide a hydrodynamic bearing device capable of sufficiently securing the axial length of a hydrodynamic bearing portion such as a radial bearing portion while efficiently discharging bubbles contained in a lubricating fluid to the outside air. A spindle motor and an information processing apparatus provided with

  A hydrodynamic bearing device according to a first aspect of the present invention includes a shaft, a substantially cylindrical sleeve, a communication passage, a lubricating fluid, a dynamic pressure bearing portion, a substantially annular first lubricating fluid reservoir, a ventilation path, It has. The sleeve has a bearing hole in which the shaft is loaded in a relatively rotatable state. The communication path is formed in a part of the sleeve along the axial direction, and communicates the open end side and the closed end side of the bearing hole in the sleeve. The lubricating fluid is stored in a space including a minute gap between the shaft and the sleeve. The hydrodynamic bearing portion is disposed between the outer peripheral surface of the shaft and the inner peripheral surface of the sleeve. The first lubricating fluid reservoir is included in the sleeve and is formed so as to intersect the communication path, and partially communicates with the communication path and stores the lubricating fluid. The ventilation path allows the first lubricating fluid reservoir and the outside air to communicate with each other.

  Here, in a hydrodynamic bearing device including a hydrodynamic bearing portion such as a radial bearing portion between opposed surfaces of a shaft and a sleeve, a communication path formed along a shaft direction in a part of the sleeve, and a substantially cylindrical sleeve And a substantially annular first lubricating fluid reservoir. And this communicating path and the 1st lubricating fluid pool part are arrange | positioned so that it may cross | intersect in the state which one part communicated. Further, the first lubricating fluid reservoir is in direct or indirect communication with the outside air via a ventilation path formed in a part of the sleeve, for example.

  Here, as said 1st lubricating fluid reservoir part, the cavity part etc. inside the sleeve comprised combining several components, etc. are considered, for example. Moreover, the ventilation path should just be formed in the outer peripheral surface of a sleeve, etc., for example so that the 1st lubricating fluid pool part included in a sleeve may communicate with external air directly or indirectly. Furthermore, the dynamic pressure bearing portion is, for example, a radial bearing portion or a conical bearing portion, and it is sufficient that a dynamic pressure generating groove is formed on at least one of the opposed surfaces of the shaft and the sleeve. Note that the first lubricating fluid reservoir portion intersects the communication passage, for example, is formed along a plane intersecting the communication passage in a state where the substantially annular first lubricating fluid reservoir portion is partially communicated. It means being.

  As a result, the first lubricating fluid reservoir portion is arranged in the sleeve, so that the dynamic pressure bearing portion such as the radial bearing portion and the first lubricating fluid reservoir portion are not aligned in the axial direction. Therefore, even when the hydrodynamic bearing device is reduced in size and thickness, the length of the hydrodynamic bearing portion can be ensured to the maximum, and the angular rigidity of the hydrodynamic bearing device can be improved.

  Further, since the communication path constituting a part of the circulation path is partially communicated with the first lubricating fluid reservoir, the bubbles contained in the circulating lubricating fluid are fed into the first lubricating fluid reservoir. Can do. Therefore, since the air bubbles that have flowed into the first lubricating fluid reservoir are directly or indirectly discharged from the ventilation path that communicates the first lubricating fluid reservoir with the outside air to the outside air, the bubbles mixed in the lubricating fluid can be efficiently removed. It can be discharged into the open air. As a result, the angular rigidity of the bearing (the magnitude of the restoring force against the tilt of the shaft due to disturbance) is improved to prevent swinging (referred to as precession due to the rotating top) and within the lubricating fluid. It is possible to obtain a hydrodynamic bearing device capable of effectively discharging the bubbles.

  A hydrodynamic bearing device according to a second invention is the hydrodynamic bearing device according to the first invention, wherein the first lubricating fluid reservoir has a cross-sectional area along the radial direction at a position intersecting the communication path. It has the smallest gap part which becomes the minimum.

  Here, the first lubricating fluid pool portion formed so as to be included in the sleeve is formed so that the cross-sectional area (gap) along the radial direction is minimized in the vicinity of the communication path.

  As a result, even when the lubricating fluid flows in the communication path constituting a part of the circulation path of the lubricating fluid in the hydrodynamic bearing device, a force acts in the direction of drawing to the communication path side due to the surface tension of the lubricating fluid. Therefore, it is possible to prevent the unnecessary lubricating fluid from flowing out to the first lubricating fluid reservoir portion side. As a result, the lubricating fluid can be smoothly circulated while supplying the necessary amount of lubricating fluid from the first lubricating fluid reservoir to the communication path.

  A hydrodynamic bearing device according to a third invention is the hydrodynamic bearing device according to the first or second invention, wherein the first lubricating fluid reservoir has a maximum cross-sectional area along the radial direction in the vicinity of the ventilation path. It has a maximum gap.

  Here, the first lubricating fluid pool part formed so as to be included in the sleeve is formed so that the cross-sectional area (gap) along the radial direction is maximized in the vicinity of the ventilation path.

  As a result, even if the first lubricating fluid reservoir is in communication with the outside air through the ventilation path, the lubricating fluid stored in the first lubricating fluid reservoir is drawn toward the communication path with a small gap. Force works in the direction. For this reason, it is possible to prevent the lubricating fluid stored in the first lubricating fluid reservoir from flowing out of the ventilation path. As a result, it is possible to reliably hold the lubricating fluid stored in the first lubricating fluid reservoir, prevent leakage from the ventilation path, and obtain a hydrodynamic bearing device having excellent impact resistance.

  A hydrodynamic bearing device according to a fourth aspect of the present invention is the hydrodynamic bearing device according to any one of the first to third aspects, wherein the first lubricating fluid reservoir is located in the circumferential direction from the ventilation path side to the communication path side. The cross-sectional area along the radial direction is formed so as to become smaller.

  Here, the first lubricating fluid pool part formed so as to be included in the sleeve is formed so that the gap gradually decreases from the ventilation path side toward the communication path side.

  Here, as a form in which the cross-sectional area along the radial direction of the first lubricating fluid reservoir is reduced, for example, a form in which the size of the gap in a plan view is changed in the circumferential direction may be used. The form which changes height in the circumferential direction may be sufficient.

  As a result, the lubricating fluid circulating in the communication passage at the portion intersecting with the communication passage may flow out to the first lubricating fluid reservoir portion side more than necessary while preventing leakage of the lubricating fluid from the ventilation passage. It can be avoided.

  A hydrodynamic bearing device according to a fifth aspect of the present invention is the hydrodynamic bearing device according to any one of the first to fourth aspects of the present invention, wherein the first lubricating fluid pool portion intersects the communication path substantially perpendicularly. .

  Thus, for example, when a plurality of sleeve members are combined to form a communication path that is substantially orthogonal to the first lubricating fluid reservoir, a groove or the like for forming the communication path with respect to the sleeve member is easily processed. can do. Therefore, it is possible to efficiently form the sleeve including the communication path by reducing the difficulty of the groove processing for the communication path.

  A hydrodynamic bearing device according to a sixth invention is the hydrodynamic bearing device according to any one of the first to fifth inventions, wherein the hub is fixed to the shaft and rotates together with the shaft, and the open end side of the sleeve And a thrust bearing portion formed between the opposite end surface and the opposite surface of the hub.

  Here, in a shaft rotation type hydrodynamic bearing device, a thrust bearing portion is disposed between opposing surfaces of a hub that is a rotation side member and a sleeve that is a stationary side member.

  Here, the thrust dynamic pressure generating groove constituting the thrust bearing portion may be formed on the hub side or may be formed on the sleeve side.

  Thus, for example, compared to a configuration in which a thrust bearing portion is provided between a thrust flange or the like fixed to one end of the shaft and the thrust plate, the thrust is closer to the open end side of the sleeve near the gravity center of the force point of the hydrodynamic bearing device. A bearing part can be arranged. Therefore, dynamic pressure can be generated in the thrust bearing portion, and the swinging can be prevented more effectively than in the past.

  A hydrodynamic bearing device according to a seventh invention is the hydrodynamic bearing device according to any one of the first to sixth inventions, wherein the hub is fixed to the shaft and rotates together with the shaft, and the open end side of the sleeve And a second lubricating fluid reservoir that is formed between the end surface of the first and the opposite surface of the hub.

  Here, in the shaft rotation type hydrodynamic bearing device, the second lubricating fluid reservoir is disposed between the opposed surfaces of the hub that is the rotation side member and the sleeve that is the stationary side member.

  Thus, in addition to the first lubricating fluid reservoir portion disposed at the position included in the sleeve, the second lubricating fluid reservoir portion is disposed in the gap between the sleeve and the hub, so that the bearing portion is sufficiently A sufficient amount of lubricating fluid can be supplied. Further, by providing a second lubricating fluid reservoir in the apparatus, the amount of liquid in the lubricating fluid reservoir can be adjusted in the second lubricating fluid reservoir.

  A hydrodynamic bearing device according to an eighth invention is the hydrodynamic bearing device according to the sixth or seventh invention, wherein the hub has a hanging portion protruding in the axial direction at a position close to the outer peripheral side of the sleeve. Have. A taper seal portion is further provided for holding the lubricating fluid in communication with the outside air in the gap between the hanging portion and the outer peripheral surface of the sleeve.

  Here, in the hydrodynamic bearing device in which the thrust bearing portion or the second lubricating fluid reservoir is formed in the gap between the end surface on the lower end side of the sleeve and the facing surface of the hub, the hanging portion of the hub and the outer peripheral surface of the sleeve Is provided with a taper seal portion that holds the lubricating fluid in communication with outside air.

  Thereby, bubbles contained in the lubricating fluid can be effectively discharged to the outside air while holding the lubricating fluid in the thrust bearing portion and the second lubricating fluid reservoir. Further, by adjusting the position of the interface of the lubricating fluid in the taper seal portion, it is possible to adjust the amount of the lubricating fluid circulating in the apparatus while ensuring the sealing performance.

  A hydrodynamic bearing device according to a ninth invention is the hydrodynamic bearing device according to the eighth invention, wherein the surface tension acting on the lubricating fluid held in the taper seal portion and the lubrication held in the first lubricating fluid reservoir portion. The surface tension acting on the fluid is balanced.

  Here, the liquid level balance between the sealing portion of the lubricating fluid in the first lubricating fluid reservoir described above and the tapered seal portion that holds the lubricating fluid in the gap between the hanging portion of the hub and the outer peripheral surface of the sleeve. The size and the like of the gap between each other are set so as to be in a state where the image is removed.

  As a result, even when two interfaces are provided in the hydrodynamic bearing device, the surface tension acting on the lubricating fluid in each gap is balanced, so that bubbles are effectively discharged to the outside air and lubricated in a stable state. Fluid can be retained in the device.

  A hydrodynamic bearing device according to a tenth aspect of the present invention is the hydrodynamic bearing device according to any one of the first to ninth aspects, wherein the hydrodynamic bearing portion is interposed through a part of a circulation path of the lubricating fluid. It communicates with the first lubricating fluid reservoir.

  Here, the dynamic pressure bearing portion such as the radial bearing portion and the first lubricating fluid pool portion are configured not to communicate directly with each other.

  As a result, it is possible to avoid the bubbles contained in the lubricating fluid stored in the first lubricating fluid reservoir from moving during operation due to the imbalance of the radial bearing or the like. Therefore, the adverse effect due to the movement of the bubbles can be reduced, and the apparatus can be operated in a more stable state.

  A hydrodynamic bearing device according to an eleventh aspect of the invention is the hydrodynamic bearing device according to any one of the first to tenth aspects of the invention, wherein the sleeve is a metal part.

  Here, as a material for forming the sleeve, for example, metal parts such as SUS, sintered metal, brass, forged product, and pressed product are used.

  Thereby, even when a thrust dynamic pressure generating groove or a radial dynamic pressure generating groove is formed on the sleeve, it is possible to configure the sleeve with high accuracy and excellent heat resistance, oil resistance, and the like.

  A hydrodynamic bearing device according to a twelfth invention is the hydrodynamic bearing device according to any one of the first to eleventh inventions, wherein the sleeve is configured by combining three components.

Here, the substantially cylindrical sleeve is configured by combining three parts.
Here, as the three parts, when the parts are combined, the first lubricating fluid reservoir is formed so as to be included in the sleeve, and the communication cylinder is formed in a part of the sleeve. Shaped parts can be used.

  As a result, the communication path and the first lubricating fluid reservoir can be formed at predetermined positions in the sleeve without requiring complicated processing or the like. Furthermore, compared to a sleeve configured by combining two parts, more complicated processing can be reduced and material loss can be minimized.

  A hydrodynamic bearing device according to a thirteenth invention is the hydrodynamic bearing device according to any one of the first to eleventh inventions, wherein the sleeve is configured by combining two parts.

Here, the substantially cylindrical sleeve is configured by combining two parts.
Here, as the two parts, when the parts are combined, the first lubricating fluid reservoir is formed so as to be included in the sleeve, and the communication cylinder is formed in a part of the sleeve. Shaped parts can be used.

  Accordingly, the number of parts can be minimized without requiring complicated processing, and the communication path and the first lubricating fluid pool can be formed at predetermined positions in the sleeve.

  A fluid dynamic bearing device according to a fourteenth invention is the fluid dynamic bearing device according to the twelfth or thirteenth invention, wherein the sleeve is formed by combining substantially cylindrical parts having a substantially L-shaped cross section along the radial direction. It is configured.

  Here, in a sleeve configured by combining a plurality of parts, a substantially cylindrical part having a substantially L-shaped cross section along the radial direction is combined.

  Thereby, the space used as the 1st lubricating fluid pool part enclosed in a sleeve can be formed easily. In addition, since the substantially L-shaped cross sections are in contact with each other in part, even when an impact, vibration, or the like is applied to the hydrodynamic bearing device, it is possible to avoid the mutual displacement of the components in the axial direction. .

  A fluid dynamic bearing device according to a fifteenth aspect of the present invention is the fluid dynamic bearing device according to any one of the twelfth to fourteenth aspects of the present invention, wherein the sleeve includes a component including a thrust bearing portion among the above components formed of resin. In the thrust dynamic pressure generating groove, metal parts are insert-molded.

  Here, in a sleeve configured by combining a plurality of parts, a part of the plurality of parts is molded with resin, and a resin part including a thrust dynamic pressure generating groove part is made of a groove part with a metal part. Insert molding.

  Here, as resin which shape | molds the said components, polyether imide, polyether sulfone, etc. can be used, for example.

  Thereby, even when a part of the parts is formed of resin, the dynamic pressure can be generated in a stable state by inserting the metal into the dynamic pressure generating groove portion. In addition, for example, by using a resin having translucency (for example, transparent, translucent, etc.) in the resin molded portion, the position of the interface of the lubricating fluid injected into the first lubricating fluid reservoir can be easily confirmed. Is possible. Therefore, it is possible to easily control the amount of lubrication during the lubrication operation for the hydrodynamic bearing device.

  A hydrodynamic bearing device according to a sixteenth aspect of the present invention is the hydrodynamic bearing device according to any one of the first to fifteenth aspects of the present invention, wherein the ventilation path is a portion where the first lubricating fluid reservoir and the communication path intersect. Is formed at the farthest position in the circumferential direction.

  Here, the ventilation path which makes the 1st lubricating fluid pool part and external air communicate is arrange | positioned in the position most distant from the communicating path in the circumferential direction.

  As a result, even when the lubricating fluid circulating in the hydrodynamic bearing device passes through the communication path, even if it flows into the first lubricating fluid reservoir, the ventilation path communicating with the outside air is disposed at the position farthest from the communication path. Therefore, leakage from the ventilation path can be effectively avoided. In addition, by changing the size of the gap in the first lubricating fluid reservoir, the surface tension of the lubricating fluid is used to more effectively prevent the lubricating fluid from leaking out of the ventilation path, resulting in impact resistance. Can be obtained.

  A hydrodynamic bearing device according to a seventeenth invention is the hydrodynamic bearing device according to any one of the first to sixteenth inventions, wherein the ventilation path is formed on the outer peripheral side surface of the sleeve.

  Here, the ventilation path which makes the 1st lubricating fluid pool part mentioned above and external air communicate is formed in the outer peripheral side surface of a sleeve.

  As a result, the lubricating fluid stored in the first lubricating fluid reservoir can effectively discharge the mixed bubbles to the outside air while breathing on the outer peripheral side surface of the sleeve.

  A spindle motor according to an eighteenth aspect of the invention is a fluid dynamic bearing device according to any one of the first to seventeenth aspects of the invention, a rotating magnet attached to a rotating side member of the fluid dynamic bearing device, and rotating with respect to the rotating magnet. A stator coil for applying a force.

Here, the above-described hydrodynamic bearing device is mounted on a spindle motor.
As a result, even in a thin hydrodynamic bearing device, the axial length of the dynamic pressure bearing portion such as a radial bearing portion can be sufficiently secured to improve the angular rigidity of the bearing, and the inside of the device can be circulated. Thus, it is possible to provide a spindle motor capable of effectively discharging bubbles contained in the lubricating fluid to the outside air.

  An information processing apparatus according to a nineteenth aspect includes the spindle motor according to the eighteenth aspect.

Here, the spindle motor described above is mounted on the information processing apparatus.
Here, the information processing apparatus includes an HDD (Hard Disc Drive) optical disk apparatus as a recording / reproducing apparatus, a magneto-optical recording / reproducing apparatus, various reproduction-only apparatuses, a cooling fan mounted on a CPU, and the like.

  As a result, even in a thin hydrodynamic bearing device, the axial length of the dynamic pressure bearing portion such as a radial bearing portion can be sufficiently secured to improve the angular rigidity of the bearing, and the inside of the device can be circulated. It is possible to provide an information processing apparatus capable of effectively discharging bubbles contained in the lubricating fluid to be discharged to the outside air.

  According to the hydrodynamic bearing device according to the present invention, the axial rigidity of the hydrodynamic bearing portion such as the radial bearing portion can be sufficiently secured to improve the angular rigidity of the bearing even if the hydrodynamic bearing device is thinned. In addition, air bubbles contained in the lubricating fluid circulating in the apparatus can be effectively discharged to the outside air.

  A spindle motor 10 equipped with a hydrodynamic bearing device 20 according to an embodiment of the present invention will be described below with reference to FIGS.

[Configuration of the entire spindle motor 10]
As shown in FIG. 1, the spindle motor 10 according to the present embodiment includes a rotor magnet 16, a stator 17 around which a plurality of coils are wound, a base 18, and a hydrodynamic bearing device 20.

  The rotor magnet 16 is attached by being multipolarly magnetized in the circumferential direction on the inner peripheral surface side of the rotor hub (hub) 15 included in the hydrodynamic bearing device 20. Then, the rotor magnet 16 rotates the rotor hub 15 around the shaft 12 by sequentially energizing the coils of the stator 17 arranged opposite to each other to generate a rotating magnetic field between the rotor magnet 16 and the stator 17.

  The base 18 is provided with motor parts such as a stator 17 and a rotor magnet 16. A substantially cylindrical portion is provided with a hollow cylindrical portion 18a for fixing the sleeve 11 and a hole 18b opened in the center thereof. A stator 17 formed of a core around which a coil is wound is fixed to a portion of the base 18 where the hole 18b is formed by adhesion or the like.

  Since the hydrodynamic bearing device 20 rotates the magnetic recording disk about the shaft 12, the rotating side member including the rotor hub 15 on which the magnetic recording disk is mounted is not connected to the fixed side member (sleeve 11 or the like). Rotate smoothly in contact. The configuration of the hydrodynamic bearing device 20 will be described in detail later.

[Configuration of Fluid Bearing Device 20]
1 and 2, the hydrodynamic bearing device 20 includes a sleeve 11, a shaft 12, a thrust flange 13, a thrust plate 14, a rotor hub 15, a taper seal portion 21, and a first fluid reservoir (first lubricating fluid reservoir). Part) 27, a second fluid reservoir (second lubricating fluid reservoir) 22, and the like.

(Sleeve 11)
The sleeve 11 has a bearing hole 11a, and is constituted by three members (first to third sleeve members 31 to 33) formed of a metal material such as iron, iron alloy, copper, or copper alloy, and the base 18 It is fixed against. Further, as shown in FIG. 2, the sleeve 11 generates a radial dynamic pressure formed on the communication path 11 b formed along the axial direction and the inner peripheral surface side of the bearing hole 11 a facing the outer peripheral surface of the shaft 12. A groove (radial bearing portion (dynamic pressure bearing portion)) 11c and a thrust dynamic pressure generating groove 33a formed on the surface facing the rotor hub 15 are provided. Further, as shown in FIGS. 2 and 3, the sleeve 11 includes a first fluid reservoir portion (first lubricating fluid reservoir portion) 27 formed in a substantially annular shape. Further, the sleeve 11 has a ventilation path 28 on the outer peripheral surface for communicating the first fluid reservoir 27 with the outside air.

  The first sleeve member 31 is used as an inner sleeve disposed on the inner side of the sleeve 11 facing the outer peripheral surface of the shaft 12. The first sleeve member 31 is a substantially annular member as a whole, and has a substantially L-shaped cross section along the radial direction. Further, as shown in FIG. 4, the first sleeve member 31 has a radial dynamic pressure generating groove 11 c on a surface facing the outer peripheral surface of the shaft 12.

  The second sleeve member 32 is used as an outer sleeve disposed on the radially outer side of the first sleeve member 31. Similar to the first sleeve member 31, the second sleeve member 32 has a substantially annular shape as a whole and has a substantially L-shaped cross section along the radial direction. The second sleeve member 32 forms the communication passage 11b, the first fluid reservoir 27, and the like in a gap formed between the second sleeve member 32 and the first sleeve member 31 in a state where the second sleeve member 32 is combined with the first sleeve member 31. . Further, the second sleeve member 32 is combined with the first sleeve member 31 so that the substantially L-shaped cross sections are brought into contact with each other. Thereby, for example, even when a large impact or vibration is applied to the hydrodynamic bearing device 20 in the axial direction and the rotation side member is about to move suddenly in the axial direction with respect to the fixed side member, the thrust flange of the shaft 12 It is possible to avoid the first sleeve member 31 being displaced in the axial direction with respect to the second sleeve member 32 by the 13 portions.

  The third sleeve member 33 is a substantially annular member disposed so as to contact the outer peripheral side of the first sleeve member 31 and the open end side of the second sleeve member 32. As shown in FIGS. 2 and 5, the third sleeve member 33 has a thrust dynamic pressure generating groove 33 a at a radially outer position on the surface facing the rotor hub 15. In addition, the third sleeve member 33 forms a ventilation path 28 that allows a first fluid reservoir 27 (described later) to communicate with the outside air in a gap between the third sleeve member 32 and the second sleeve member 32. Further, the third sleeve member 33 forms a second fluid reservoir 22 to be described later in the gap between the rotor sleeve 15 and the rotor hub 15 arranged to face each other.

  The communication path 11b is a through hole formed so as to penetrate the sleeve 11 in the axial direction, and is formed in the gap between the first sleeve member 31 and the second sleeve member 32 described above. The communication path 11b circulates the lubricating fluid 26 in the gap including the bearing portion by the circulating force of the lubricating fluid 26 generated by the asymmetric radial dynamic pressure generating groove 11c and the like. The communication passage 11b is configured by first to third communication passages 11ba, 11bb, and 11bc.

  The first communication path 11ba is a hole portion formed when the inner peripheral surface of the second sleeve member 32 formed with the longitudinal groove and the outer peripheral surface of the first sleeve member 31 are combined. It arrange | positions along an axial direction from the end side. The second communication passage 11bb is a hole portion formed when the inner peripheral surfaces of the second sleeve member 32 and the third sleeve member 33 formed with vertical grooves and the outer peripheral surface of the first sleeve member 31 are combined. The sleeve 11 is arranged along the axial direction from the open end side. The third communication passage 11bc is a hole portion formed when the end surface of the second sleeve member 32 formed with the transverse groove and the end surface of the first sleeve member 31 are combined, and is arranged along the radial direction. Yes. Instead of the communication path 11b, a communication hole may be formed by drilling the sleeve 11.

  As shown in FIG. 4, the radial dynamic pressure generating groove 11c is a herringbone-shaped dynamic pressure generating groove, and generates dynamic pressure by the rotation of the shaft 12 on the rotating side. Further, as shown in FIG. 4, the radial dynamic pressure generating groove 11 c has an asymmetric herringbone shape in the axial direction (a <b or c <d in FIG. 4). For this reason, the flow of the lubricating fluid 26 is formed in a desired direction in the gap (radial bearing portion) between the sleeve 11 and the shaft 12 (in the case of FIG. 4, from the top also in the radial bearing portion in FIG. 2). A downward circulating flow is formed). Thereby, the lubricating fluid 26 can be efficiently circulated in the hydrodynamic bearing device 20, and the bubbles mixed in the lubricating fluid 26 can be effectively discharged to the external space.

  The thrust dynamic pressure generating groove 33a is formed in an annular shape on the surface (upper surface) facing the rotor hub 15 in the third sleeve member 33 described above. Further, the thrust dynamic pressure generating groove 33 a is formed on the outer surface in the radial direction on the upper surface of the third sleeve 33. Thereby, in the hydrodynamic bearing device 20 of this embodiment, compared with the case where the thrust dynamic pressure generating groove is formed on the opposing surface of the thrust flange 13 and the thrust plate 14, the dynamic pressure is generated at a position on the radially outer side. Thus, the tilt of the shaft 12 can be corrected to prevent the swinging.

  Between the shaft 12 including the radial dynamic pressure generating groove (radial bearing portion) 11c (see FIG. 2) and the thrust dynamic pressure generating groove (thrust bearing portion) 33a and the bearing hole 11a of the sleeve 11, and the rotor hub 15 and the sleeve 11 A clearance 26 is filled with a lubricating fluid 26. When the rotating member including the shaft 12 rotates, the lubricating fluid 26 flows into the dynamic pressure generating groove and generates a pumping pressure.

  The radial dynamic pressure generation groove 11c may be formed not on the sleeve 11 side shown in FIG. Further, the radial dynamic pressure generating groove 11c may have two spiral shapes (substantially C-shaped) instead of the herringbone shape. Further, it may be a conical bearing having the characteristics of both a radial bearing portion and a thrust bearing portion.

(Shaft 12)
The shaft 12 is a member made of a metal material and having a cylindrical outer peripheral surface having a diameter of about 2.0 to 4.0 mm (for example, a columnar member or a cylindrical member), and is formed in the bearing hole 11a. Inserted in a rotatable state. Further, a disc-shaped thrust flange 13 having a circular opening at the center portion is joined to the lower end portion of the shaft 12 by caulking, press fitting, welding, or the like. The thrust flange 13 may be integrally formed with the shaft 12. Since the shaft 12 is used as an axis of rotation center, for example, a material with relatively high hardness such as SUS is used and is processed by cutting and polishing.

(Thrust flange 13)
The thrust flange 13 is a substantially disk-shaped member, and is fixed to or integrally with the shaft 12 as described above. The thrust flange 13 is accommodated in a space surrounded by the sleeve 11 and the thrust plate 14.

  The upper surface peripheral portion of the thrust flange 13 is opposed to a step portion (a bottom surface portion of the first sleeve member 31) formed below the sleeve 11.

  When the thrust bearing portion is disposed in the gap between the opposing surfaces of the rotor hub 15 and the sleeve 11, the thrust flange 13 only needs to have a retaining function. Therefore, in this case, since it is not necessary to form the thrust dynamic pressure generating groove, it can be configured as a relatively thin disk-shaped member. In this case, the thrust flange 13 may not be provided as long as a retaining member is provided separately (see the retaining member 315a in FIG. 10).

(Thrust plate 14)
The thrust plate 14 is a substantially disk-shaped member attached so as to cover the lower opening of the hydrodynamic bearing device 20.

  When the thrust bearing portion is disposed in the gap between the opposing surfaces of the rotor hub 15 and the sleeve 11, it is not necessary to form the thrust dynamic pressure generating groove, so the thrust plate 14 is formed relatively thin. Can do.

(Rotor hub 15)
The rotor hub 15 has a substantially cup shape and has a through hole at a substantially central portion. The upper end portion of the shaft 12 is fixed to the through hole by a press-fit adhesive method or the like. A rotor magnet 16 of the spindle motor 10 is attached to the rotor hub 15 and faces the stator 17 in the radial direction. In addition, a recording medium such as a magnetic recording disk is fixed to the rotor hub 15 to constitute a magnetic recording / reproducing device such as a hard disk device as a whole. Further, the rotor hub 15 has a hanging portion 15 a that protrudes along the axial direction from the surface on the side facing the sleeve 11.

  The hanging part 15a protrudes along the axial direction so as to be close to the outer peripheral side of the sleeve 11 (third sleeve member 33). The drooping portion 15 a forms a taper seal portion 21 in a gap between the drooping portion 15 a and the outer peripheral surface of the third sleeve member 33.

  As shown in FIG. 2, the taper seal portion 21 is formed by an outer peripheral surface of the third sleeve member 33 that is inclined so that a gap between the drooping portion 15 a spreads downward in the axial direction. Since the taper seal portion 21 has a gap narrowing upward in the axial direction, the lubricating fluid 26 stored in the second fluid reservoir 22 can be held by the action of surface tension.

(First fluid reservoir 27)
As shown in FIGS. 2, 3, and 5, the first fluid reservoir 27 is formed so as to be included in the sleeve 11 in a state where the first sleeve member 31 and the second sleeve member 32 are combined. It is a substantially annular gap. Further, the first fluid reservoir 27 partially intersects the communication passage 11b formed along the axial direction substantially perpendicularly. Furthermore, as shown in FIGS. 2 and 3, the first fluid reservoir 27 is formed so that the size of the gap in the radial direction changes along the circumferential direction.

  Specifically, as shown in FIG. 3, the gap in the radial direction (cross-sectional area) increases as the distance from the position close to the ventilation path 28 that communicates the first fluid reservoir 27 with the outside air in the circumferential direction. A seal structure (seal part) 30 is formed to reduce the. That is, the first fluid reservoir 27 has a minimum clearance 27 a at the position farthest from the ventilation path 28 and a maximum clearance 27 b at a position closest to the ventilation path 28.

  In the minimum gap portion 27a, the radial gap is the minimum gap d. On the other hand, in the maximum gap portion 27b, the radial gap is the maximum gap D, and the relationship between them is D> d.

  That is, as shown in FIG. 3, the first fluid reservoir 27 has a seal structure 30 in which the size of the radial gap gradually decreases from the ventilation path 28 in the circumferential direction. For this reason, the lubricating fluid 26 stored in the first fluid reservoir 27 has a capillary force (suction force) due to the action of surface tension from the side of the ventilation path 28 having the largest gap to the side of the communication path 11b having the smallest gap. Work. Therefore, in the present embodiment, the lubricating fluid 26 can be stably held in the first fluid reservoir 27 with the gas-liquid boundary surface 26a as a boundary, as shown in FIG. As a result, even if the first fluid reservoir 27 communicates with the outside air via the ventilation path 28, the stored lubricating fluid 26 can be prevented from leaking out of the ventilation path 28. .

  Further, the lubricating fluid 26 circulates in the communication path 11b by the circulating force of the lubricating fluid 26 generated by the asymmetric radial dynamic pressure generating groove 11c. And the 1st fluid reservoir part 27 and the communicating path 11b cross | intersect in the state which a part communicated in the position of the minimum clearance gap part 27a. At this time, the lubricating fluid 26 that circulates in the communication passage 11b is drawn from the communication passage 11b to the first fluid pool portion by a suction force to the lubricating fluid 26 due to a change in the size of the radial gap in the first fluid pool portion 27. It is suppressed that it flows out more than necessary to 27.

  The communication path 11b is formed so that the cross-sectional area becomes smaller than the size of the cross-sectional area at the portion of the first fluid reservoir 27 that intersects the communication path 11b. As a result, the bubbles included in the lubricating fluid 26 that circulates in the communication path 11b are subjected to a force that tends to move to the side with the larger gap, and therefore effectively from the circulation path to the first fluid reservoir 27. And bubbles can be sent.

  Regarding the size relationship of the gap at the intersection of the communication path 11b and the first fluid reservoir 27, the size of the gap of the communication path 11b is at least the size of the gap of the maximum gap 27b in the first fluid reservoir 27. Smaller than that. Further, regarding the size relationship of the gap at the intersection of the communication passage 11b and the first fluid reservoir 27, not only the size relationship of the radial gap and the axial clearance, but also the equivalent diameter of the communication passage 11b, the communication passage 11b, You may set by the magnitude | size with the equivalent diameter in the cross | intersection part with the 1st fluid reservoir part 27. FIG. Here, the equivalent diameter means a representative length indicating how much the diameter of the flow channel is equivalent to a set of circular tubes from the point of flow.

(Second fluid reservoir 22)
As shown in FIG. 2, the second fluid reservoir 22 is formed in a gap between the facing surfaces of the sleeve 11 and the rotor hub 15. Further, the lubricating fluid 26 stored in the second fluid reservoir 22 communicates with the outside air at the taper seal portion 21 formed between the hanging portion 15a and the third sleeve member 33 described above. Therefore, the lubricating fluid 26 is in communication with the outside air at the gas-liquid boundary surface 26a in the first fluid reservoir 27 and the taper seal portion 21 on the second fluid reservoir 22 side. Bubbles contained in the lubricating fluid 26 can be discharged to the outside air in the fluid reservoir 22.

  In the present embodiment, in addition to the substantially annular first fluid reservoir 27 included in the sleeve 11, the second fluid reservoir 22 is also provided between the opposed surfaces of the rotor hub 15 and the sleeve 11.

  Thereby, compared with the conventional hydrodynamic bearing device, the volume of the lubricating fluid reservoir can be increased and more lubricating fluid 26 can be stored in the device. Further, both the first and second fluid reservoirs 27 and 22 are formed to communicate with the outside air. Therefore, when the lubricating fluid 26 circulating in the apparatus flows into each lubricating fluid reservoir, the bubbles contained in the lubricating fluid 26 can be effectively discharged to the outside air.

  Further, since the taper seal portion 21 is provided on the open side of the second fluid reservoir portion 22, the lubricating fluid 26 stored in the apparatus is adjusted by adjusting the position of the lubricating fluid 26 at the taper seal portion 21. The amount of liquid can be adjusted.

  Further, the size of the gap of the taper seal portion 21 on the second fluid reservoir portion 22 side is determined by the surface tension acting on the lubricating fluid 26 stored in the first fluid reservoir portion 27 and the lubricating fluid 26 in the vicinity of the taper seal portion 21. The size is set so as to balance the surface tension acting on the surface. Thereby, the lubricating fluid 26 can be stored in a balanced manner in the apparatus.

<Circulation path of lubricating fluid 26>
In the hydrodynamic bearing device 20 of this embodiment, the circulation path of the lubricating fluid 26 is formed in the device by the above-described configurations.

  The lubricating fluid 26 is supplied from the radial bearing portion in which the radial dynamic pressure generating groove 11c is formed to the first communication path 11ba (between the first sleeve member 31 and the second sleeve member 32) and the third communication path 11bc (first Between the sleeve member 31 and the second sleeve member 32), the first fluid reservoir 27, and the second communication passage 11bb (between the first sleeve member 31, the second sleeve member 32, and the third sleeve member 33), It circulates in the apparatus in the order of the second fluid reservoir 22.

[Features of the hydrodynamic bearing device 20]
(1)
In the hydrodynamic bearing device 20 of the present embodiment, as shown in FIG. 2 and the like, the shaft 12 is rotatably loaded in the bearing hole 11a of the sleeve 11, and a part of the sleeve 11 is axially provided. A communication path 11b is provided. A minute gap formed between the shaft 12 and the sleeve 11 is filled with a lubricating fluid 26. As shown in FIG. 4, a radial dynamic pressure generating groove 11 c is formed on the inner peripheral surface of the sleeve 11 facing the outer peripheral surface of the shaft 12. As shown in FIG. 3, the sleeve 11 contains a substantially annular first fluid reservoir 27 for storing the lubricating fluid 26. The first fluid reservoir 27 intersects with the communication passage 11 b in a part of the sleeve 11 and communicates with the outside air through the ventilation path 28.

  Thus, the first fluid reservoir 27 is disposed in the vicinity of the radial bearing portion (radial dynamic pressure generating groove 11c) in the axial direction by disposing the first fluid reservoir 27 at a position included in the sleeve 11. You can avoid that. Therefore, a radial bearing portion formed between the outer peripheral surface of the shaft 12 and the inner peripheral surface of the sleeve 11 can be ensured to the maximum in the axial direction. Therefore, even if the hydrodynamic bearing device 20 is thinned and the length in the axial direction cannot be sufficiently secured, the axial length of the radial bearing portion is sufficiently secured, the angular rigidity of the bearing is improved, and the runout is improved. Around can be effectively prevented.

  Further, in the hydrodynamic bearing device 20 of the present embodiment, the first fluid reservoir portion 27 provided in the sleeve 11 is communicated with the outside air through the ventilation path 28.

  Thereby, the lubricating fluid 26 stored in the first fluid reservoir 27 contained in the sleeve 11 can breathe via the ventilation path 28. Accordingly, it is possible to effectively discharge bubbles generated or mixed in the lubricating fluid 26 when circulating in the apparatus while storing a sufficient amount of the lubricating fluid 26 in the apparatus.

(2)
In the hydrodynamic bearing device 20 of the present embodiment, as shown in FIGS. 3 and 5, the radial gap is at the position where the first fluid reservoir 27 intersects with the communication path 11 b in communication with the minimum gap d. A minimum gap portion 27a.

  As a result, a suction force acts on the lubricating fluid 26 stored in the first fluid reservoir 27 toward the position intersecting the communication path 11b due to the action of surface tension. Therefore, the lubricating fluid 26 circulating in the communication passage 11b can be prevented from flowing into the first fluid reservoir 27 more than necessary even when the lubricating fluid 26 is in a position communicating with the first fluid reservoir 27. . As a result, even when the first fluid reservoir 27 is arranged so as to communicate with a part of the circulation path of the lubricating fluid 26, the lubricating fluid 26 is reduced without interfering with the circulation of the lubricating fluid 26. Can smoothly supply the lubricating fluid 26 into the circulation path.

(3)
In the hydrodynamic bearing device 20 of the present embodiment, as shown in FIGS. 3 and 5, the first fluid reservoir 27 has a maximum gap portion where the radial gap is the maximum gap D at the position where the ventilation path 28 is formed. 27b.

  Thereby, the lubricating fluid 26 can be made difficult to move to the side of the ventilation path 28 where the gap is large due to the action of surface tension. Therefore, even when the first fluid reservoir 27 in which the lubricating fluid 26 is stored is communicated with the outside air via the ventilation path 28, the leakage of the lubricating fluid 26 from the ventilation path 28 can be effectively prevented. it can.

(4)
In the hydrodynamic bearing device 20 of the present embodiment, as shown in FIGS. 3 and 5, the size of the radial gap (cross-sectional area) decreases as the first fluid reservoir 27 moves away from the ventilation path 28 in the circumferential direction. It has the seal structure 30 which becomes.

  Thus, the sealing structure 30 can apply a suction force by capillary force to the lubricating fluid 26 from the side of the maximum gap 27b near the ventilation path 28 toward the side of the minimum gap 27a intersecting the communication path 11b. it can. Therefore, the lubricating fluid 26 can be stably stored in the first fluid reservoir 27 while preventing leakage from the ventilation path 28.

  Further, since the ventilation path (ventilation hole) 28 is formed in the vicinity of the maximum gap portion 27 b, the air bubbles accumulated in the first fluid reservoir 27 are always the ventilation path 28 regardless of the posture of the hydrodynamic bearing device 20. Since it is formed in the vicinity, the lubricating fluid 26 does not leak out of the ventilation path 28 due to impact or the like.

(5)
In the hydrodynamic bearing device 20 of the present embodiment, as shown in FIG. 5, the first fluid reservoir 27 is formed so as to intersect substantially perpendicularly to the communication path 11 b formed along the axial direction. .

  Thereby, for example, when forming the communicating path 11b along the axial direction, the first and second communicating paths 11ba and 11bb constituting the communicating path 11b may be formed as vertical grooves along the axial direction. it can. Therefore, the groove processing can be facilitated, and the desired communication path 11b can be formed efficiently and while reducing the processing cost.

(6)
In the hydrodynamic bearing device 20 of the present embodiment, as shown in FIG. 2, a thrust bearing portion (thrust dynamic pressure generating groove 33 a) is provided in the gap between the opposed surfaces of the rotor hub 15 and the sleeve 11.

  Thereby, compared with the structure which has arrange | positioned the thrust bearing part between the opposing surfaces of the conventional thrust flange 13 and the thrust board 14 grade | etc., A thrust bearing part can be arrange | positioned in the position close | similar to the power point gravity center of the hydrodynamic bearing apparatus 20. it can. Therefore, even when the shaft 12 is inclined, the angular rigidity of the bearing can be improved more effectively than the conventional one by the dynamic pressure generated in the thrust bearing portion, and the swinging can be effectively prevented.

(7)
In the hydrodynamic bearing device 20 of the present embodiment, as shown in FIG. 2, the second fluid reservoir 22 is disposed in the gap between the opposing surfaces of the rotor hub 15 and the sleeve 11.

  Thus, by providing the second fluid reservoir portion 22 in addition to the first fluid reservoir portion 27 included in the sleeve 11, a sufficient amount of the lubricating fluid 26 can be held in the fluid bearing device 20. Therefore, it is possible to effectively prevent the occurrence of problems due to the lack of the lubricating fluid 26 and extend the life of the hydrodynamic bearing device 20.

(8)
In the hydrodynamic bearing device 20 of the present embodiment, as shown in FIG. 2, a taper is formed in the gap between the hanging portion 15 a formed on a part of the rotor hub 15 and the outer peripheral surface of the sleeve 11 (third sleeve member 33). A seal portion 21 is provided.

  Thereby, air bubbles contained in the lubricating fluid 26 stored in the second fluid reservoir portion 22 disposed between the opposing surfaces of the rotor hub 15 and the sleeve 11 are effectively discharged from the taper seal portion 21 and from there. Can be effectively suppressed.

(9)
In the hydrodynamic bearing device 20 of the present embodiment, the surface tension acting on the lubricating fluid 26 stored in the first fluid reservoir 27 and the surface acting on the lubricating fluid 26 near the taper seal portion 21 on the second fluid reservoir 22 side. The size of the gap such as the taper seal portion 21 is set so that the tension is balanced.

  As a result, even in the hydrodynamic bearing device 20 having two or more open portions in the device, the lubricating fluid 26 can be made to flow by applying surface tension to the lubricating fluid 26 so as to balance the both open portions. It can be stably held in the apparatus.

(10)
In the hydrodynamic bearing device 20 of the present embodiment, the first fluid reservoir portion 27 is connected to the radial bearing portion (radial dynamic pressure generating groove 11c) via the communication passage 11b that constitutes a part of the circulation path of the lubricating fluid 26. Communicate.

  Thereby, during operation of the apparatus, it is possible to avoid movement of bubbles contained in the lubricating fluid 26 stored in the first fluid reservoir 27 due to imbalance in the radial bearing portion. Therefore, it is possible to easily avoid the occurrence of problems caused by bubbles moving in the apparatus during the operation of the apparatus.

(11)
In the hydrodynamic bearing device 20 of the present embodiment, a metal material such as iron, an iron alloy, copper, or a copper alloy is used as a material for forming the sleeve 11.

  Thereby, the sleeve 11 excellent in heat resistance and oil resistance can be obtained using a relatively inexpensive material. In addition, even when the dynamic pressure generating groove is formed, it is possible to form a highly accurate groove to realize highly accurate dynamic pressure generation.

(12)
In the hydrodynamic bearing device 20 of the present embodiment, as shown in FIGS. 2 and 5, the sleeve 11 is configured using three members, that is, a first sleeve member 31, a second sleeve member 32, and a third sleeve member 33. Yes.

  Thereby, the communication path 11b and the 1st fluid pool part 27 formed in the sleeve 11 can be easily formed by combining the member of a comparatively simple shape. Therefore, the above-described configuration of the sleeve 11 can be obtained with a simple configuration without requiring complicated processing or the like for the sleeve 11.

(13)
In the hydrodynamic bearing device 20 of the present embodiment, as shown in FIGS. 2 and 5, the first and second sleeve members 31 and 32 out of the three members described above have a substantially L-shaped cross section. A character-shaped member is used in combination.

  Thereby, it can play the role of the retaining in the axial direction by combining so that the substantially L-shaped portions of each other come into contact with each other. Therefore, even when the sleeve 11 is configured by combining a plurality of members, it is possible to effectively prevent a part of the sleeve 11 from being displaced together with the shaft 12 due to vibration or impact to the hydrodynamic bearing device 20.

(14)
In the hydrodynamic bearing device 20 of the present embodiment, as shown in FIGS. 2, 3, and 5, the ventilation path 28 that allows the first fluid reservoir 27 to communicate with the outside air is provided, and the first fluid reservoir 27 is connected to the communication passage 11b. It is formed at a position farthest from the intersecting position.

  Thereby, even when the lubricating fluid 26 circulating in the apparatus moves in the communication path 11b, the lubricating fluid 26 does not easily leak from the ventilation path 28 because it is the position farthest from the ventilation path 28. Therefore, in combination with the sealing effect due to the shape of the first fluid reservoir 27, the lubricating fluid 26 stored in the first fluid reservoir 27 is more effectively prevented from leaking out of the ventilation path 28. be able to.

(15)
In the hydrodynamic bearing device 20 of the present embodiment, as shown in FIGS. 2, 3, and 5, the ventilation path 28 that communicates the first fluid reservoir 27 with the outside air is provided on the outer peripheral surface side (second and second) of the sleeve 11. 3 between the sleeve members 32 and 33).

  Thereby, the lubricating fluid 26 stored in the first fluid reservoir 27 can be respired on the outer peripheral surface side of the sleeve 11.

(16)
The spindle motor 10 of this embodiment is equipped with the above-described hydrodynamic bearing device 20.

  Thereby, even if it is the hydrodynamic bearing device 20 made thin, the axial length of the radial bearing portion can be sufficiently secured to improve the angular rigidity of the bearing, and the lubricating fluid can be used when circulating in the device. Thus, it is possible to provide the spindle motor 10 capable of obtaining the effect that bubbles generated or mixed in the air can be effectively discharged to the outside air.

[Other Embodiments]
As mentioned above, although one Embodiment of this invention was described, 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.

(A)
In the said embodiment, the sleeve 11 which encloses the communicating path 11b and the 1st fluid pool part 27 demonstrated and gave the example comprised by three members (1st-3rd sleeve members 31-33). However, the present invention is not limited to this.

  For example, as shown in FIGS. 6 and 7, a sleeve 111 constituted by two members, first and second sleeve members 131 and 132, may be used. Even in this case, the second fluid reservoir 22 is formed between the surfaces facing the rotor hub 15, and the sleeve 111 that includes the communication path 111 b and the first fluid reservoir (first lubricating fluid reservoir) 127 is easily configured. be able to. Further, similarly to the above-described embodiment, by using the members having substantially L-shaped radial cross sections in combination, the substantially L-shaped portions are brought into contact with each other and can function as a retaining member. .

  The second sleeve member 132 preferably has a thrust dynamic pressure generating groove 132a on the side facing the rotor hub 15, similarly to the third sleeve member 33 of the above embodiment. Thereby, the angular rigidity of the bearing is effectively improved by arranging the support point of the rotation side member at a position where the radial distance is maximized as close to the power point of the hydrodynamic bearing device 120 as possible. Thus, the same effect as described above can be obtained.

  However, as compared with the combination of two members, the shape of each member can be simplified to facilitate processing and reduce material loss as in the above embodiment. More preferably, the sleeve is formed by combining two members.

(B)
In the above-described embodiment, the three members constituting the sleeve 11 have been described with examples using all metal members. However, the present invention is not limited to this.

  Of the three members, for example, the third sleeve member 33 may be formed of a resin excellent in heat resistance, oil resistance, and the like.

  In this case, when the thrust dynamic pressure generating groove is formed on the facing surface side of the sleeve 11 with respect to the rotor hub 15, as shown in FIG. 8, a metal member 133b is insert-molded into a part of the resin member 133a. The third sleeve member 133 may have a dynamic pressure generating groove formed in the metal member 133b. Thereby, even when resin parts are used as one member constituting the sleeve, the dynamic pressure can be generated with high accuracy.

(C)
In the above embodiment, an example in which the thrust bearing portion (thrust dynamic pressure generating groove 33a) is disposed in the gap between the opposing surfaces of the rotor hub 15 and the sleeve 11 has been described. However, the present invention is not limited to this.

  For example, without providing a thrust bearing portion between the opposing surfaces of the rotor hub 15 and the sleeve 211, as shown in FIG. 9, the opposing surfaces of the thrust flange 213 and the thrust plate 214 that rotate integrally with the shaft 212. A thrust bearing portion may be disposed in the gap (here, the thrust dynamic pressure generating groove 233a is formed on the thrust flange 213 side). Or you may arrange | position a thrust bearing part between the opposing surfaces of the thrust flange 213 and the sleeve 211 further.

  However, in the point of preventing the rotation-side member from swinging by generating dynamic pressure at a position as close as possible to the power point in the hydrodynamic bearing device 20 and at a maximum position in the radial direction, as in the above embodiment, the rotor hub More preferably, a thrust bearing portion is disposed between the opposing surfaces of the sleeve 15 and the sleeve 11.

(D)
In the above embodiment, the so-called flange-type hydrodynamic bearing device 20 in which the thrust flange 13 is attached to the shaft 12 has been described as an example. However, the present invention is not limited to this.

  For example, as shown in FIG. 10, a so-called flangeless type hydrodynamic bearing device 320 having no flange portion with respect to the shaft 312 and a spindle motor 310 on which this is mounted may be used. In this case, by attaching the retaining member 315a to the rotor hub 315, the retaining member 315a is brought into contact with the step portion of the third sleeve member 311c, so that the shaft 312 is in the bearing hole 311a of the sleeve 311. It is possible to avoid falling out of the inside.

(E)
In the said embodiment, the sealing function in the 1st fluid reservoir part 27 was given and demonstrated with the example given by changing the magnitude | size of a radial direction clearance gap in the circumferential direction. However, the present invention is not limited to this.

  For example, the sealing mechanism may be provided by changing the size of the cross-sectional area along the radial direction of the first lubricating fluid reservoir in the circumferential direction. That is, the size in the circumferential direction may be changed not only in the size of the radial gap but also in the size of the axial gap, or in both the radial direction and the axial direction. .

(F)
In the embodiment described above, an example in which the radial dynamic pressure generating groove 11c is formed as an asymmetric groove in order to apply a circulating force for circulating the lubricating fluid 26 filled in the gap in the hydrodynamic bearing device 20 has been described. However, the present invention is not limited to this.

  For example, the thrust dynamic pressure generating groove may be formed as an asymmetric groove to generate a circulating force on the thrust bearing portion side. Alternatively, both the radial and thrust dynamic pressure generating grooves may be formed as asymmetric grooves to apply a force for circulating the lubricating fluid 26 in the apparatus.

(G)
In the embodiment described above, an example in which a metal material such as iron, an iron alloy, copper, or a copper alloy is used as the material constituting the sleeve 11 has been described. However, the present invention is not limited to this.

  For example, a sintered metal, SUS, brass, a forged product, or the like can be used in addition to the metal material.

(H)
In the above embodiment, the hydrodynamic bearing device including the radial bearing portion and the thrust bearing portion has been described as an example. However, the present invention is not limited to this.

  For example, the present invention can be applied to a hydrodynamic bearing device including a conical bearing.

(I)
In the above-described embodiment, an example in which the hydrodynamic bearing device 20 according to the present invention is mounted on the spindle motor 10 has been described. However, the present invention is not limited to this.

  For example, as shown in FIG. 11, a spindle motor 110 (fluid bearing device) mounted on a magnetic recording / reproducing apparatus (recording / reproducing apparatus, information processing apparatus) 150 having a recording head 152 that performs recording / reproducing on a recording / reproducing disk 151. The present invention can naturally be applied to 120).

  Further, the recording / reproducing apparatus is not limited to the magnetic recording / reproducing apparatus, and can be mounted on other recording / reproducing apparatuses such as an optical disk.

  Furthermore, the present invention can also be applied to a hydrodynamic bearing device included in a spindle motor that rotates a cooling fan mounted on a CPU as an information processing device.

  The hydrodynamic bearing device of the present invention can sufficiently secure the axial length of the radial bearing portion to improve the angular rigidity of the bearing even in the thinned hydrodynamic bearing device, and circulates in the device. Since the bubbles contained in the lubricating fluid can be effectively discharged to the outside air, the present invention is widely applicable to hydrodynamic bearing devices mounted on various information processing apparatuses.

A sectional view showing composition of a spindle motor carrying a fluid dynamic bearing device concerning one embodiment of the present invention. The expanded sectional view which shows the structure of the hydrodynamic bearing device mounted in the spindle motor of FIG. FIG. 3 is a cross-sectional view taken along line AA in FIG. 2. FIG. 3 is a development view showing asymmetric radial dynamic pressure generating grooves formed on a sleeve surface included in the hydrodynamic bearing device of FIG. 2. The conceptual diagram which shows the structure where the communicating path formed in the sleeve contained in the hydrodynamic bearing apparatus of FIG. 2 and a 1st fluid reservoir part cross | intersect. Sectional drawing which shows the structure of the spindle motor carrying the hydrodynamic bearing apparatus which concerns on other embodiment of this invention. The expanded sectional view which shows the structure of the hydrodynamic bearing apparatus mounted in the spindle motor of FIG. Sectional drawing of the member which comprises the sleeve contained in the hydrodynamic bearing apparatus which concerns on further another embodiment of this invention. Sectional drawing which shows the structure of the hydrodynamic bearing apparatus which concerns on further another embodiment of this invention. Sectional drawing which shows the structure of the spindle motor carrying the hydrodynamic bearing apparatus which concerns on further another embodiment of this invention. Sectional drawing which shows the structure of the magnetic recording / reproducing apparatus carrying the said hydrodynamic bearing apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Spindle motor 11 Sleeve 11a Bearing hole 11b Communication path 11ba 1st communication path 11bb 2nd communication path 11bc 3rd communication path 11c Radial dynamic pressure generating groove (radial bearing part (dynamic pressure bearing part))
12 Shaft
13 Thrust flange 14 Thrust plate 15 Rotor hub (hub)
15a Suspended portion 16 Rotor magnet 17 Stator 18 Base 18a Hollow cylindrical portion 18b Hole 20 Fluid bearing device 21 Taper seal portion 22 Second fluid reservoir (second lubricating fluid reservoir)
26 Lubricating fluid 26a Gas-liquid interface 27 First fluid reservoir (first lubricating fluid reservoir)
27a Minimum clearance 27b Maximum clearance 28 Ventilation path 30 Seal structure (seal)
31 First sleeve member 32 Second sleeve member 33 Third sleeve member 33a Thrust dynamic pressure generating groove (thrust bearing portion)
110 spindle motor 111 sleeve 111b communication path 120 hydrodynamic bearing device 127 first fluid reservoir (first lubricating fluid reservoir)
128 Ventilation path 131 First sleeve member 132 Second sleeve member 132a Thrust dynamic pressure generating groove (thrust bearing portion)
133 Third sleeve member 133a Resin member 133b Metal member 150 Magnetic recording / reproducing apparatus (information processing apparatus)
151 Recording / Reproducing Disc 152 Recording Head 211 Sleeve 212 Shaft
213 Thrust flange 214 Thrust plate 220 Hydrodynamic bearing device 233a Thrust dynamic pressure generating groove 310 Spindle motor 311 Sleeve 311a Bearing hole 311b Communication hole 311c Third sleeve member 312 Shaft 315 Rotor hub (hub)
315a Retaining member 320 Hydrodynamic bearing device d Minimum gap D Maximum gap

Claims (19)

The axis,
A substantially cylindrical sleeve having a bearing hole in which the shaft is loaded in a relatively rotatable state;
A communication path that is formed in a part of the sleeve along the axial direction and communicates the open end side and the closed end side of the bearing hole in the sleeve;
A lubricating fluid stored in a space including a minute gap between the shaft and the sleeve;
A hydrodynamic bearing portion disposed between the outer peripheral surface of the shaft and the inner peripheral surface of the sleeve;
A substantially annular first lubricating fluid reservoir that is included in the sleeve, is formed to intersect the communicating path, partially communicates with the communicating path, and stores the lubricating fluid;
A ventilation path for communicating the first lubricating fluid reservoir and the outside air;
A hydrodynamic bearing device. The first lubricating fluid reservoir has a minimum gap that minimizes the cross section along the radial direction at a position intersecting the communication path.
The hydrodynamic bearing device according to claim 1. The first lubricating fluid reservoir has a maximum gap in the vicinity of the ventilation path where the cross section along the radial direction is maximum.
The hydrodynamic bearing device according to claim 1. The first lubricating fluid reservoir is formed in a circumferential direction so that a cross section along the radial direction becomes smaller from the ventilation path side toward the communication path side.
The hydrodynamic bearing device according to any one of claims 1 to 3. The first lubricating fluid reservoir intersects substantially perpendicularly to the communication path;
The hydrodynamic bearing device according to any one of claims 1 to 4. A hub that is fixed relative to the shaft and rotates with the shaft;
A thrust bearing portion formed between an end surface on the open end side of the sleeve and a surface facing the hub;
Further equipped with,
The hydrodynamic bearing device according to any one of claims 1 to 5. A hub that is fixed relative to the shaft and rotates with the shaft;
A second lubricating fluid reservoir formed between an end surface of the sleeve on the open end side and a surface facing the hub;
Further equipped with,
The hydrodynamic bearing device according to any one of claims 1 to 6. The hub has a drooping portion projecting in the axial direction at a position close to the outer peripheral side of the sleeve,
A taper seal that holds the lubricating fluid in communication with outside air in a gap between the hanging portion and the outer peripheral surface of the sleeve;
The hydrodynamic bearing device according to claim 6 or 7. The surface tension acting on the lubricating fluid held in the tapered seal portion and the surface tension acting on the lubricating fluid held in the first lubricating fluid reservoir are balanced.
The hydrodynamic bearing device according to claim 8. The dynamic pressure bearing portion communicates with the first lubricating fluid reservoir through a part of the circulation path of the lubricating fluid.
The hydrodynamic bearing device according to any one of claims 1 to 9. The sleeve is a metal part,
The hydrodynamic bearing device according to claim 1. The sleeve is configured by combining three parts,
The hydrodynamic bearing device according to any one of claims 1 to 11. The sleeve is configured by combining two parts,
The hydrodynamic bearing device according to any one of claims 1 to 11. The sleeve is configured by combining substantially cylindrical parts having a substantially L-shaped cross section along the radial direction.
The hydrodynamic bearing device according to claim 12 or 13. In the sleeve, a part including a thrust bearing portion among the parts is formed of a resin, and a metal part is insert-molded in a portion of the thrust dynamic pressure generating groove.
The hydrodynamic bearing device according to claim 12. The ventilation path is formed at a position farthest in the circumferential direction with respect to a portion where the first lubricating fluid reservoir and the communication path intersect.
The hydrodynamic bearing device according to any one of claims 1 to 15. The ventilation path is formed on the outer peripheral side surface of the sleeve,
The hydrodynamic bearing device according to any one of claims 1 to 16. The hydrodynamic bearing device according to any one of claims 1 to 17,
A rotating magnet attached to the rotating side member of the fluid dynamic bearing device;
A stator coil for applying a rotational force to the rotating magnet;
With spindle motor. An information processing apparatus comprising the spindle motor according to claim 18.

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