JP2009191933A - Fluid bearing device, spindle motor using the same, and information device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fluid bearing device preventing a lubricating fluid from leaking to the outside even if thermal impact is repeatedly applied in the fluid bearing device used for an information device such as an HDD (hard disk drive). <P>SOLUTION: The fluid bearing device 1 is constituted such that an adhesive reservoir part 25 which is a clearance formed by an annular wall taper 19b of a cover 19 and a projecting opposed wall 7b of a sleeve 7 is enlarged toward the axial outside or the radial outside. Consequently, even if an adhesive 23 is separated by thermal impact or the like to cause the overflow of the lubricating fluid, the lubricating fluid 21 is drawn into the bearing interior side by the capillary force of the adhesive reservoir part 25, thereby preventing the lubricating fluid 21 from leaking to the outside. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a hydrodynamic bearing device mounted on an information device such as an HDD (Hard Disk Drive), a spindle motor using the same, and an information device.

  2. Description of the Related Art In recent years, various information devices equipped with HDDs have been made lighter, thinner and smaller for convenience of carrying.

  On the other hand, it is necessary to maintain and improve the high storage capacity while being small. In order to improve the storage capacity, how to accurately and accurately control the position of the head and the disk is an important technical issue. For this reason, as a spindle motor bearing used in the HDD, a hydrodynamic bearing device with high rotational accuracy is mainly used.

  The hydrodynamic bearing device includes a fixed portion and a rotating portion, and a lubricating fluid is filled between the fixed portion and the rotating portion to constitute the bearing portion. And when a rotation part rotates, it has the structure which generates a dynamic pressure in a bearing part and supports a rotation part via lubricating fluid.

  For example, Patent Document 1 discloses a technique for ensuring the length of the radial bearing portion in order to increase the rigidity of the bearing in the radial direction. That is, an inverted cup-shaped cover having an annular wall provided on the outermost periphery is bonded and fixed to the end face of the sleeve via a gap, and a sealing portion for the lubricating fluid is constituted by the gap between the cover and the sleeve. Accordingly, since the seal portion can be formed in a portion having a larger diameter than the shaft, the length of the radial bearing portion formed by the gap between the shaft and the sleeve can be further increased. Thereby, the radial rigidity of the hydrodynamic bearing device can be increased.

  FIG. 13A is a partial cross-sectional view showing the bonding state between the cover 101 and the bonding portion 103 of the sleeve 102 of the conventional hydrodynamic bearing device. In addition, in order to make the bonding state easier to understand, the gap of the bonding portion 103 is expressed exaggerated larger than the actual state.

  As shown in FIG. 13A, the adhesive 104 filling the gap between the cover 101 and the sleeve 102 is not filled on the entire circumferential surface, but the gap between the adhesive 104 and the sleeve 102 or the cover 101 and the adhesive. An air part 105 in a state where air partially enters is interposed in the gap 104.

The cover 101 is formed using a resin material because of its complicated shape, and the sleeve 102 is made of a copper-based alloy or the like having good machinability in order to increase processing accuracy.
JP 2006-161967 A

  As described above, in the conventional hydrodynamic bearing device, the linear expansion coefficients of the cover 101, the adhesive 104, and the sleeve 102 are greatly different. Therefore, for example, when the temperature becomes high, the cover 101 and the adhesive 104 tend to expand more than the sleeve 102, so that a force is generated in the direction F <b> 1, and a tensile stress strain is generated between the adhesive 104 and the sleeve 102. The agent 104 tends to peel from the sleeve 102. As a result, as shown in FIG. 13B, a peeling portion 107 is generated between the adhesive 104 and the sleeve 102. The lubricating fluid 106 flows into the air part 105 connected by the peeling part 107 via the peeling part 107.

  On the other hand, the peeling part 107 generated in this way receives a force in the opposite direction at a low temperature.

  As described above, since the stress is repeatedly applied to the adhesive 104 due to repeated thermal shock, the adhesive 104 is fatigued and the peeling portion 107 is enlarged as shown in FIG. As a result, there has been a problem that the lubricating fluid 106 leaks to the outside.

  Accordingly, an object of the present invention is to provide a hydrodynamic bearing device in which a lubricating fluid does not leak to the outside even when thermal shock is repeatedly applied.

  In order to achieve this object, the hydrodynamic bearing device of the present invention includes a shaft, a bearing hole into which the shaft is rotatably inserted, one end face of which is an open end, A cover that covers the open end side end face with a space, an adhesive that fixes the cover to the sleeve, and an adhesive formed between the outer periphery of the cover and the annular recess provided on the open end side of the sleeve A reservoir, a gap between the shaft and the sleeve, and a lubricating fluid held in a space in the sleeve including an open end side space between the cover and the sleeve, and the adhesive reservoir is an open end side end surface of the sleeve It is the structure which is a clearance gap which becomes large as it goes to an axial direction outer side or radial direction outer side.

  As described above, according to the present invention, even if the adhesive peels off due to thermal shock in the region filled with the adhesive and the lubricating fluid leaks, the lubricating fluid is drawn into the bearing inside by the capillary force of the adhesive pool portion. Therefore, it is possible to prevent the lubricating fluid from leaking out of the bearing.

  Furthermore, the adhesive filled in the adhesive pool portion also tends to enter the inside of the adhesive pool portion by capillary force. As a result, the air intervening in the joint surface between the annular recess provided in the sleeve forming the adhesive pool and the adhesive is pushed out, and the area of the adhesive contacting the joint surface can be increased. In addition, the adhesive strength is improved, and even when the thermal shock is repeatedly applied, the adhesive portion is less likely to be peeled off.

  Hereinafter, embodiments of a hydrodynamic bearing device and a spindle motor according to the present invention will be described with reference to the drawings. In the following description, for the sake of convenience, the vertical direction of the drawing is expressed as “axially upper side”, “axially lower side”, etc., but does not limit the actual usage state of the hydrodynamic bearing device and the spindle motor.

(Embodiment 1)
FIG. 1 shows a cross-sectional view of an HDD (information device) 3 on which a spindle motor 2 provided with a hydrodynamic bearing device 1 according to Embodiment 1 of the present invention is mounted.

[Configuration of HDD 3 as a whole]
As shown in FIG. 1, the HDD 3 according to the present embodiment has a head unit 4 and a spindle motor 2 mounted therein. Each recording / reproducing head 4a writes information to the disk (recording medium) 5 or reproduces already written information.

  The head unit 4 is equipped with a plurality of recording / reproducing heads 4 a and is disposed so as to be close to the front and back surfaces of the disk 5.

  The disk 5 is a disk-shaped recording medium having a diameter attached to the HDD 3 of, for example, 0.85 inch, 1.0 inch, 1.8 inch, 2.5 inch, or 3.5 inch.

  The base 6 is formed, for example, by processing a plate material such as SECC or an aluminum alloy, and the front and back surfaces are formed by applying Ni plating or electrodeposition coating. A part of the hermetically sealed housing of the HDD 3 is configured.

  Further, the base 6 has a sleeve 7 of the hydrodynamic bearing device 1 fixed by adhesion, press-fitting, or the like in the vicinity of the center portion thereof, and a rotor hub 8 is attached to the rotating side portion of the hydrodynamic bearing device 1.

  The rotor hub 8 is formed in a substantially inverted cup shape by using, for example, magnetic ferritic stainless steel (SUS430 or the like). And it fits to the outer peripheral upper end part of the shaft 9 of the hydrodynamic bearing device 1, is fixed by adhesion, press fitting, or the like, and rotates integrally with the shaft 9.

  Further, the rotor hub 8 has a central hole 8a into which the shaft 9 is inserted into the upper end portion, a magnet holding portion 8b which is a cylindrical hanging wall to which the rotor magnet 10 is attached, and a circular shape on which the disc-like disk 5 is placed. And a stepped disk mounting surface 8c.

  The disk 5 is sandwiched between the disk fixing surface 11a of the substantially disc-shaped disk clamp 11 and the disk mounting surface 8c. The disc 5 is pressed and fixed by the disc clamp 11 by tightening the screw 12 to the screw portion 9 a provided on the shaft 9 through the screw fixing hole 11 b provided in the center portion of the disc clamp 11. A predetermined pressing force is applied to the disk 5 in a state where the pressing portion 11 c of the disk clamp 11 is in contact with the position regulating surface 8 d of the rotor hub 8.

  The spindle motor 2 is a device that serves as a rotational drive source for rotationally driving the disk 5, and includes a rotor magnet 10, a stator core 13, a stator coil 14, and a hydrodynamic bearing device 1 that is a bearing portion.

[Description of each member constituting the spindle motor 2]
The rotor magnet 10 is an annular member in which adjacent magnetic poles are alternately arranged with N and S poles, and is formed of an Nd—Fe—B resin magnet or the like.

  The rotor magnet 10 is attached to the magnet holding portion 8b of the rotor hub 8 via a fixed gap in the radial direction with the stator core 13, and is fixed by, for example, adhesion.

The stator core 13 has a plurality of salient pole portions arranged at substantially equal angular intervals along the circumferential direction, and a stator coil 14 is wound around each of the salient pole portions.
The stator core 13 applies a rotational force to the rotor magnet 10 by a magnetic field generated by passing a current through the stator coil 14.

  The hydrodynamic bearing device 1 is a hydrodynamic bearing device included in the spindle motor 2 and is disposed near the center of the spindle motor 2.

[Description of each member constituting the hydrodynamic bearing device 1]
The hydrodynamic bearing device 1 is a shaft rotation type hydrodynamic bearing device in which a shaft 9 rotates with respect to a substantially cylindrical sleeve 7 fixed to a base 6.

  FIG. 2 shows a cross-sectional view of the hydrodynamic bearing device 1. In the hydrodynamic bearing device 1, a shaft 9 is inserted into a bearing hole 15 of a sleeve 7 through a gap (space) so as to be rotatable. A thrust flange 16 is fixed to the lower end portion of the shaft 9 by external fitting or screws. A thrust plate 17 is fixed to the bottom of the sleeve 7 so as to face the lower surface of the thrust flange 16 in a posture having a gap in the axial direction.

  Further, in addition to these configurations, a cover 19 is provided between the upper end surface of the sleeve 7 via the space S1 and has one vent hole 18 communicating with the outside air. In the hydrodynamic bearing device 1, one circulation communication passage 20 extending in parallel with the axis O is drilled at a location near the outer peripheral surface of the sleeve 7.

  Through the circulation communication path 20, the large-diameter portion 15 a that is a circular step-shaped recess that forms a space in which the thrust flange 16 is accommodated is communicated with the space S 1. The shaft 9 and the thrust flange 16 may be formed integrally.

  Further, the inside of the sleeve 7 includes the space between the outer peripheral surface of the shaft 9 and the bearing hole 15 of the sleeve 7 and the space S1 that is the open end side space between the inner side surface of the cover 19 and the open end side end surface of the sleeve 7. The lubricating fluid 21 is held in this space. A lubricating fluid reservoir 22 is formed on the inner peripheral surface of the cover 19 facing the shaft 9 so as to expand toward the opening side, and communicates with the outside air and accumulates the lubricating fluid 21 by capillary force.

  Further, a radial dynamic pressure groove (not shown) such as a herringbone shape is formed on the inner peripheral surface of the bearing hole 15 of the sleeve 7 at the top and bottom, and when the shaft 9 and the sleeve 7 rotate relatively, A radial fluid bearing in which dynamic pressure is generated by the force of the lubricating fluid 21 scraped by the radial dynamic pressure groove, and the shaft 9 and the sleeve 7 are rotatably supported in a radial direction (radial direction) in a non-contact manner through a predetermined gap. Is configured.

  The radial dynamic pressure grooves may be provided on the outer peripheral surface of the shaft 9 or on both the inner peripheral surface of the bearing hole 15 and the outer peripheral surface of the shaft 9.

  On the other hand, a thrust dynamic pressure groove (not shown) having a spiral shape or the like is formed on the upper surface and the lower surface of the thrust flange 16, and the thrust flange 16 attached to the shaft 9 and the sleeve 7 are relatively rotated. At this time, dynamic pressure is generated by the force of the lubricating fluid 21 scraped out by the thrust dynamic pressure groove, and the shaft 9 and the sleeve 7 can rotate freely in a thrust direction (axial direction) through a predetermined gap without contact. A supported thrust fluid bearing is configured.

  Further, the radial dynamic pressure groove is not limited to the herringbone shape, and may be a spiral shape. Similarly, the thrust dynamic pressure groove is not limited to a spiral shape, and may be a herringbone shape.

  The sleeve 7 and the cover 19 are fixed with an adhesive 23 to prevent the lubricating fluid 21 from leaking outside. The adhesion between the sleeve 7 and the cover 19 will be described in more detail.

  FIG. 3 is an enlarged cross-sectional view of the cover 19 and the sleeve 7 where the adhesive 23 is applied. The cover 19 has a circular annular wall 19a extending downward in the axial direction on the outer peripheral side, and an annular wall taper 19b having an angle θ1 is provided below the outer peripheral surface of the annular wall 19a. This angle θ1 is an angle formed by the axial lower surface of the annular wall 19a of the cover 19 and the tapered surface of the annular wall taper 19b.

  In addition, a circular annular recess 7a is provided on the outer peripheral side of the sleeve 7, and a protrusion-facing wall 7b having a taper of an angle θ2 smaller than the angle θ1 of the annular wall taper 19b is provided on the inner peripheral surface of the annular recess 7a. ing. This angle θ2 is an angle formed by the inner bottom surface of the annular recess 7a of the sleeve 7 and the tapered surface of the protrusion facing wall 7b. In this embodiment, for example, the angle θ1 is set to 70 degrees and the angle θ2 is set to 30 degrees.

  In addition, for example, an oil-resistant thermosetting epoxy adhesive 23 is applied to the shoulder 7c that is the inner bottom surface of the annular recess 7a and the small-diameter cylindrical portion 7d that is formed on the inner peripheral surface of the annular recess 7a. ing. The adhesive 23 is a tapered surface of the protrusion facing wall 7b having an angle θ2, and can be held inside the annular recess 7a, so that it does not overflow. The material of the sleeve 7 is, for example, a copper alloy such as brass, and the surface is subjected to electroless nickel plating.

  Further, as the material of the cover 19, a polyetherimide resin or the like is used. FIG. 4 shows a state where the cover 19 is positioned and fixed with respect to the sleeve 7 in the direction of arrow A shown in FIG.

  As shown in FIG. 4, the position of the cover 19 in the axial direction with respect to the sleeve 7 is restricted with the positioning portion 19 c in contact with the sleeve 7. Since the annular wall 19a of the cover 19 is combined with the small-diameter cylindrical portion 7d of the sleeve 7 and is pushed into the annular recess 7a of the sleeve 7 at the same time, the adhesive 23 is pushed in, so that the adhesive 23 overflows outward from the annular recess 7a. Try to.

  At this time, in the state in which the cover 19 and the sleeve 7 are combined, the angle θ1 of the annular wall taper 19b is larger than the angle θ2 of the protrusion facing wall 7b, so that it is formed by the annular wall taper 19b and the protrusion facing wall 7b. The adhesive reservoir 25, which is a gap, becomes larger toward the outside of the sleeve 7, that is, radially outward or axially outward.

  Therefore, the adhesive 23 receives a force drawn in the direction of the arrow F2 by the capillary force in the adhesive reservoir 25.

  Further, the second adhesive reservoir 26 which is a gap formed between the lower surface in the axial direction of the annular wall 19a and the shoulder 7c of the annular recess 7a, the inner peripheral surface 19d of the annular wall 19a and the annular recess of the sleeve 7 Similarly, the capillary force also acts on the third adhesive reservoir 27, which is a gap formed between the small diameter cylindrical portion 7d of 7a.

  As a result, as shown in FIG. 5A, the air portion 24 interposed in the joint surface between the annular recess 7a provided in the sleeve 7 forming the adhesive pool portion 25 and the adhesive 23 is in a direction in which the pressure is small. It is pushed out of the sleeve 7. Then, as shown in FIG. 5B, the air part 24 moves in the direction of the arrow M and goes out of the joint surface between the annular recess 7 a and the adhesive 23.

  In addition, since the viscosity of the adhesive 23 is temporarily lowered by heating at the time of thermosetting, the air in the air part 24 is easily moved and easily discharged to the outside. As described above, as a result of the air in the air portion 24 being discharged to the outside, the adhesive 23 that is in contact with the joint surface between the adhesive 23 and the cover 19 or the sleeve 7 is cured with a large area. For this reason, adhesive strength improves and it becomes difficult to generate | occur | produce peeling in an adhesion part even if a thermal shock is repeatedly applied.

  Further, as shown in FIG. 4, in the third adhesive reservoir 27, when the thermal shock is applied, for example, when the temperature becomes high, the adhesive 23 and the sleeve 7 are caused by the difference in the linear expansion coefficient between the cover 19 and the sleeve 7. Tensile stress is generated during this period. On the other hand, since the compressive stress is generated between the adhesive 23 and the sleeve 7 in the adhesive reservoir 25, the deformation stresses cancel each other. As a result, the tensile stress of the third adhesive reservoir 27 can be reduced and the adhesive 23 can be prevented from peeling off from the sleeve 7.

  Further, as shown in FIG. 6, even when the adhesive 23 and the cover 19 or the sleeve 7 are separated from each other and the lubricating fluid 21 leaks outside from the adhesive reservoir 25, Since the boundary surface 23a with the atmosphere is on the inner side from the outermost part of the adhesive reservoir 25, the leakage lubricating fluid 21a is secured in the holding space S2. That is, the holding space S <b> 2 has a gap that is a gap angle (θ <b> 1 − θ <b> 2) formed by the protrusion facing wall 7 b of the sleeve 7 and the annular wall taper 19 b of the cover 19. Since this gap increases toward the outside of the sleeve 7, that is, outward in the radial direction or outward in the axial direction, the leakage lubricating fluid 21a is pulled in the direction of arrow F3 by the capillary force and acts to leak the lubricating lubricating fluid. A force is generated to hold 21a to the inside of the bearing. Thereby, it is possible to prevent the leaking lubricating fluid 21a from leaking out of the bearing.

  As described above, in the hydrodynamic bearing device of the present embodiment, even if the lubricating fluid 21 leaks from the adhesive reservoir 25 by making the angle θ1 of the annular wall taper 19b larger than the angle θ2 of the protrusion facing wall 7b. In addition, it is possible to provide a fluid dynamic bearing device that can hold the leakage lubricating fluid 21a to the inside of the bearing by capillary force and prevent the leakage lubricating fluid 21a from leaking outside the bearing.

  Further, when the adhesive 23 is filled, the capillary force acts on the adhesive 23 in the gap between the annular wall taper 19b and the protrusion facing wall 7b, whereby the air in the air portion 24 is discharged to the outside, and the adhesive 23 and the cover 19 are discharged. Since the area of the adhesive 23 in contact with the joint surface with the sleeve 7 can be increased, the adhesive strength is improved, and even when thermal shock is repeatedly applied, the fluid bearing is less likely to cause peeling and the lubricating fluid 21 from leaking out. An apparatus can be provided.

  Further, by filling the adhesive reservoir 25 with the adhesive 23, the tensile stress generated in the third adhesive reservoir 27 and the compressive stress generated in the adhesive reservoir 25 cancel each other's stress. As a result, the stress acting on the third adhesive reservoir 27 can be reduced. For this reason, since it becomes difficult for peeling to occur in the adhesive reservoir 25 and the third adhesive reservoir 27, it is possible to provide a hydrodynamic bearing device in which the lubricating fluid 21 is unlikely to leak.

  By using such a hydrodynamic bearing device, it is possible to provide a highly reliable spindle motor and information device in which the lubricating fluid inside the bearing is less likely to leak out of the bearing.

(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 above embodiment, as shown in FIG. 2, the sleeve 7 is made of nickel-plated copper alloy and the cover 19 is made of polyetherimide resin. However, the invention is not limited to this. .

  For example, a combination using a stainless steel material or a sintered material as a material for the sleeve 7 or a combination using another resin or a metal material as a material for the cover 19 may be used.

  Also in this case, the same effect as in the first embodiment can be obtained. In particular, when stainless steel without plating is used for the sleeve 7 or when a metal material is used for the cover 19, the wettability of the adhesive 23 is improved, so that the sealing characteristics of the adhesive 23 can be further improved. .

(B)
In the above embodiment, the angle θ1 is set to 70 degrees and the angle θ2 is set to 30 degrees as shown in FIG. 4, but the present invention is not limited to this.

  For example, the angle θ2 may be set to 5 degrees or more, more preferably 15 degrees or more.

  By setting the angle θ2 to 5 degrees or more, the adhesive 23 can be secured inside the protrusion facing wall 7b. In this case, the difference between the angle θ1 and the angle θ2 is preferably 3 to 45 degrees in order to obtain the capillary force.

(C)
In the above embodiment, as shown in FIG. 3, the adhesive 23 is first applied to the annular recess 7 a of the sleeve 7 for assembly. However, the present invention is not limited to this.

  For example, as shown in FIG. 7A, a cover side adhesive 31a is applied to the inner peripheral surface 30b of the annular wall 30a of the cover 30, and a sleeve side adhesive 31b is applied to the shoulder portion 32a of the sleeve 32. May be. Alternatively, it may be applied to the small diameter cylindrical portion 32b of the sleeve 32 (adhesive is not shown).

  In this case, the same effect as in the first embodiment can be obtained. For example, an adhesive suitable for applying to the cover side adhesive 31a in a narrow gap is used, and the sleeve side adhesive 31b is used as the sleeve side adhesive 31b. By using an adhesive having a high sealing property and different from the cover side adhesive 31a, an adhesive suitable for each purpose can be used at each position. Thereby, more stable adhesion can be performed.

  In addition, when the amount of the adhesive 31 is controlled as shown in FIG. 7B, the adhesive 31 is more accurately replenished by replenishing the adhesive 31 with the dispenser 33 before heating for thermosetting. You can control the amount.

(D)
In the above embodiment, as shown in FIG. 3, the protrusion facing wall 7b and the annular wall taper 19b are formed by straight lines having an angle, but the present invention is not limited to this.

  For example, as shown in FIG. 8A, the protrusion facing wall 34 and the annular wall taper 35 may be configured by a curve having a radius R. Further, as shown in FIG. 8B, the annular wall taper 36 may be a C surface.

  Also in this case, the same effect as in the first embodiment can be obtained as long as the gap formed by the protrusion facing wall 34 and the annular wall taper 35 is an enlarged portion that expands toward the radially outer side or the axially outer side. In order to obtain a capillary force by this gap, the radius R and the C surface are preferably 0.15 or more.

(E)
In the above embodiment, as shown in FIG. 3, the outer peripheral portion of the sleeve 7 is constituted by a straight circumferential surface, but the present invention is not limited to this.

  For example, as shown in FIG. 9A, a thin portion 37 a may be provided on the distal end side of the outer peripheral portion of the sleeve 37.

  As shown in FIG. 9B, the thin portion 37a has a light spring property when the hydrodynamic bearing device 1 is assembled into the base 38. When the hydrodynamic bearing device 1 is mounted on the base 38, the mounting accuracy at the center position of the hydrodynamic bearing device 1 is improved. Not only the height but also the length of the bonding portion 39 can be made longer, so that the bonding strength between the sleeve 37 and the base 38 is improved.

(F)
In the above embodiment, as shown in FIG. 1, the holding portion of the sleeve 7 of the base 6 is configured by a straight circumferential surface, but is not limited thereto.

  As shown in FIG. 10, the base 40 may be provided with an inclined portion 40 a on an extension line of the protrusion facing wall 41 b of the sleeve 41.

  Even in the gap formed by the inclined portion 40a of the base 40 and the cover 42, an angle θ3 is provided so that the gap increases toward the outer side in the radial direction or the outer side in the axial direction. In the meantime, the lubricating fluid 43 can be held toward the inside of the bearing by capillary force.

(G)
In the embodiment described above, the vent hole 18 is provided on the upper side in the axial direction of the cover 19 as shown in FIG. 2, but the present invention is not limited to this.

  As shown in FIG. 11A, a configuration may be employed in which the vent holes 44 are provided in the radial direction and the adhesive reservoir 45 is provided. Further, as shown in FIG. 12, there may be a configuration in which there is no vent hole and a cover 46 is provided on the lower side in the axial direction, and the lubricating fluid 47 is sealed and bonded by the adhesive reservoir 48.

  In either case, the same effect as in the first embodiment can be obtained if the adhesive reservoir 45 or 48 is a gap that expands toward the radially outer side or the axially outer side. FIG. 11B shows a cross section from the A direction in FIG. 11A in order to facilitate understanding of the states of the lubricating fluid 49 and the air 50.

(H)
In the above embodiment, as shown in FIG. 1, the spindle motor 2 used in the HDD 3 as an information device has been described with reference to an example in which the present invention is applied. However, the present invention is not limited to this.

  For example, as a device on which the spindle motor of this embodiment is mounted, in addition to the HDD, a magneto-optical disk device, an optical disk device, a floppy (registered trademark) disk device, a laser printer device, a laser scanner device, a video cassette recorder device, a data streamer device. It can be mounted on a device or the like.

  The hydrodynamic bearing device according to the present invention and the spindle motor and information device using the hydrodynamic bearing device can prevent the lubricating fluid from leaking to the outside even when a thermal shock or the like is applied. It is useful for information devices used in environmental conditions and spindle motors that require thin and high-speed rotation.

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 Partial sectional view of cover and sleeve in an adhesive application state in Embodiment 1 of the present invention The fragmentary sectional view of the state which combined the cover and sleeve in Embodiment 1 of this invention (A) (b) is a partial sectional view of a cover and a sleeve for explaining an action of capillary force in Embodiment 1 of the present invention. Partial sectional view of a cover and a sleeve in a state where the lubricating fluid leaks from the adhesive portion in the first embodiment of the present invention. (A) (b) is a partial sectional view of a cover and a sleeve for explaining an application state of an adhesive in other embodiments of the present invention (A) and (b) are partial sectional views of a cover and a sleeve according to another embodiment of the present invention. (A) Partial cross-sectional view of a sleeve and a sleeve provided with a thin wall portion in the outer peripheral portion of the sleeve in another embodiment of the present invention, and (b) A thin wall portion provided in the outer peripheral portion of the sleeve in another embodiment of the present invention. Partial sectional view of spindle motor The fragmentary sectional view of the crevice formed between the base and cover in other embodiments of the present invention (A) Cross-sectional view of a hydrodynamic bearing device according to another embodiment of the present invention, (b) Cross-sectional view of a hydrodynamic bearing device according to another embodiment of the present invention as viewed from the direction A in FIG. Sectional drawing of the hydrodynamic bearing apparatus in other embodiment of this invention. (A) (b) is a fragmentary sectional view which shows the adhesion state of the cover and sleeve of a conventional fluid dynamic bearing device

Explanation of symbols

1 Fluid Bearing Device 2 Spindle Motor 3 HDD (Information Device)
7 sleeve 7a annular recess 7b projection facing wall 7c shoulder 7d small diameter cylindrical portion 9 shaft 15 bearing hole 19 cover 19a annular wall 19b annular wall taper 21 lubricating fluid 21a leakage lubricating fluid 23 adhesive 24 air portion 25 adhesive reservoir 26 2 Adhesive reservoir 27 Third adhesive reservoir S2 Holding space

Claims (4)

A shaft,
A sleeve having a bearing hole into which the shaft is rotatably inserted, and one end surface of which is an open end;
A cover that covers the open end side end surface of the sleeve in a state having a space;
An adhesive for fixing the cover to the sleeve;
An adhesive reservoir formed between the outer periphery of the cover and an annular recess provided on the opening end side of the sleeve;
A lubricating fluid held in a space in the sleeve including a gap between the shaft and the sleeve, and an open end side space between the cover and the sleeve;
A hydrodynamic bearing device in which the adhesive reservoir is a gap that increases from the end surface on the opening end side of the sleeve toward the outside in the axial direction or the outside in the radial direction.   The hydrodynamic bearing device according to claim 1, wherein a boundary surface between the adhesive and the atmosphere is formed in the adhesive reservoir.   A spindle motor using the hydrodynamic bearing device according to claim 1. An information device using the spindle motor according to claim 3.

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