JP2006292177A - Dynamic-pressure bearing arrangement - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a dynamic-pressure bearing arrangement capable of assuring bonding strength and bending strength and furthermore rigidity of a dynamic-pressure bearing by assuring long enough for bonding length between each component. <P>SOLUTION: The dynamic-pressure bearing arrangement composes a radial dynamic-pressure bearing part 3 in a clearance between the inner peripheral surface of a sleeve 2 and the outer peripheral surface of a shaft member 1 and composes a thrust dynamic-pressure bearing part 4 in clearance between the axial one end of the sleeve 2 and the opposite surface of the shaft member 1 opposed to the one end and composes a capillary tube sealing part 45 in a clearance between the sleeve 2 and the shaft member 1 opposed to the sleeve 2. A lubricant fluid is continuously filled into the radial dynamic-pressure bearing part 3, the thrust dynamic-pressure bearing part 4 and the capillary tube sealing part 45 without being blocked and forms gas-liquid interface with outside air only within the capillary tube sealing part 45. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a hydrodynamic bearing device including a shaft member and a sleeve, and the shaft member and the sleeve can be rotated relative to each other without contact with each other. For example, as a bearing device for a disk drive device such as a magnetic disk or an optical disk, In addition, it can be used as a bearing device for various devices that require high rotational accuracy.

  BACKGROUND ART A hydrodynamic bearing device is used as a bearing device for various devices that require high rotational accuracy. For example, in a hard disk drive, the recording density of the hard disk increases with time, and accordingly, the rotational speed and rotational accuracy of the disk are further increased. In order to meet the demand for higher rotational speed and higher rotational accuracy of the disk, it is suitable to use a hydrodynamic bearing device.

  The configuration of a conventional dynamic pressure bearing device for a disk drive device is as follows. Insert the above-mentioned shaft member of the hub assembly, in which one end of the shaft member is joined and fixed to the center of the hub on which the disk is placed, into a sleeve that has been subjected to groove processing for generating radial dynamic pressure, and for generating thrust dynamic pressure The thrust plate subjected to the groove processing is fixed to the other end portion of the shaft member, the thrust plate is sandwiched between the counter plate and the sleeve, the counter plate is fixed to the stator or the like, and the other end portion of the shaft member and the sleeve A gap between them is sealed with an adhesive or the like to form a bearing set.

  Next, the radial dynamic pressure bearing portion between the shaft member and the sleeve and the thrust dynamic pressure bearing portion between the thrust plate, the counter plate and the sleeve are filled with a lubricating fluid, and the inner peripheral surface side of the peripheral wall of the hub is filled. A rotor magnet is fixed to form a rotor set. In addition, a base set in which insulating paper and a flexible wiring board are attached to a base frame is configured, and a core winding set in which a conductive wire is wound around a laminated core coated with an insulating paint and used as a drive coil is used as the base set. Assemble the stator assembly. A disk driving fluid dynamic bearing motor is obtained by assembling the rotor set to the stator set.

JP-A-6-178490

  In recent years, various devices using a hydrodynamic bearing device, such as a disk drive device, have become more demanding to reduce the thickness as well as demands for higher speed rotation and higher rotation accuracy. Is also required. However, the structure of the conventional hydrodynamic bearing device does not sufficiently meet the demand for thinning. The following items can be cited as factors that hinder the thinning of the hydrodynamic bearing device.

  It is necessary to increase the bonding strength between the constituent members so that the bearing device is not damaged by external stress such as impact. For example, it is necessary to increase the bonding strength between the hub and the shaft member, the bonding strength between the shaft member and the thrust plate, and the bonding strength between the counter plate and the sleeve beyond a predetermined strength. However, for example, when the shaft member and the thrust plate are joined by press-fitting, the static friction coefficient is about 0.2, and it is necessary to increase the joining length in order to obtain a sufficiently large joining strength. If this joining length is lengthened, it becomes an obstructive factor for thinning of the hydrodynamic bearing device. Further, it is necessary to increase the bending strength by increasing the thickness of each component so that the bearing device is not damaged by external stress. For example, it is necessary to increase the thickness of the thrust plate, the thickness of the counter plate, and the like. Increasing the thickness of these members becomes an impediment to reducing the thickness of the fluid dynamic bearing device.

  In order to increase the rigidity of the radial dynamic pressure bearing, it is necessary to increase the axial length of the bearing portion, which is an obstacle to the reduction in thickness. Furthermore, it is necessary to install a seal device for preventing leakage of the lubricating fluid at the axial end of the hydrodynamic bearing device. For example, in the case of a capillary seal, it is necessary to secure a sufficient amount of lubricating fluid by increasing the depth dimension of the capillary seal in order to eliminate defects caused by evaporation of the lubricating fluid and increase reliability. In addition, it becomes an impediment to the thinning of the hydrodynamic bearing device. In addition, a magnetic fluid seal may be used instead of a capillary seal or together with a capillary seal. However, the magnetic fluid seal requires a magnet and a pole piece, and their thickness is an obstructive factor for reducing the thickness of a hydrodynamic bearing device. Become.

  The present invention has been made to solve the above-described problems of the prior art, and by ensuring a sufficiently long joining length between the constituent members, the joining strength and the bending strength, and further, the hydrodynamic bearing It is an object of the present invention to provide a hydrodynamic bearing device that can ensure rigidity.

The hydrodynamic bearing device according to claim 1, a cylindrical sleeve;
A shaft member having an outer peripheral surface facing the inner peripheral surface of the sleeve, and rotating relative to the sleeve about the rotation center axis;
A radial dynamic pressure bearing portion having a radial dynamic pressure generating groove array formed in a gap between the inner peripheral surface of the sleeve and the outer peripheral surface of the shaft member and inducing a fluid dynamic pressure at the time of relative rotation;
One end-side thrust dynamic pressure having a thrust dynamic pressure generating groove array formed in a gap between one axial end surface of the sleeve and the opposite surface of the shaft member facing the one end surface to induce fluid dynamic pressure during relative rotation A bearing portion;
A capillary seal portion formed in a gap between the sleeve and the shaft member facing the sleeve, connected to the one-end-side thrust dynamic pressure bearing portion, and having a gap size that increases as it moves away from the one-end-side thrust dynamic pressure bearing portion;
A radial dynamic pressure bearing portion, one end side thrust dynamic pressure bearing portion, and a lubricating fluid that is continuously filled without interruption in the capillary seal portion and forms a gas-liquid interface with the outside air only within the capillary seal portion. It is characterized by that.

  In the fluid dynamic bearing device according to claim 2, a slip-off preventing mechanism for preventing the shaft member from slipping relative to the sleeve is formed between the one end side thrust fluid pressure bearing portion and the capillary seal portion. It is characterized by.

  In the fluid dynamic bearing device according to claim 3, the annular member is fixed to the shaft member so as to face the other end surface of the sleeve in the axial direction, and the capillary seal portion is formed between the outer peripheral surface of the sleeve and the inner peripheral surface of the annular member. It is formed between them.

  In the hydrodynamic bearing device according to the fourth aspect, the annular member is fixed to the shaft member so as to face the other end surface of the sleeve in the axial direction, and the slip prevention mechanism is related to the other end surface of the sleeve and the one end surface of the annular member. It is configured by stopping.

  In the hydrodynamic bearing device according to claim 5, the shaft member is formed with a peripheral wall portion surrounding a part of the outer peripheral portion of the sleeve, and a jetty portion protruding from the peripheral wall portion to the other end side. And it is fixed in contact with each of the jetty portions.

  The fluid dynamic bearing device according to claim 6 is characterized in that the annular member is fixed to the shaft body via an adhesive.

In the dynamic pressure bearing device according to claim 7, the capillary seal portion is formed in a radial gap between the outer peripheral surface of the sleeve and the inner peripheral surface of the shaft member facing the outer peripheral surface.
The inclination angle of the outer peripheral surface of the sleeve constituting the capillary seal portion with respect to the rotation center axis is formed larger than the inclination angle of the inner peripheral surface of the shaft member constituting the capillary seal portion with respect to the rotation center axis. .

In the hydrodynamic bearing device according to claim 8, a flange portion extending in the radial direction is provided on the outer peripheral portion on one end side of the sleeve as an integral or separate body with the sleeve,
The one-end-side thrust dynamic pressure bearing portion is formed in a gap between one end surface of the flange portion and the facing surface of the shaft member facing the one end surface.

The hydrodynamic bearing device according to claim 9 is for generating thrust dynamic pressure that induces fluid dynamic pressure at the time of relative rotation in the gap between the other axial end surface of the sleeve and the opposing surface of the shaft member facing the other end surface. The other end side thrust dynamic pressure bearing portion having the groove row is formed,
The lubricating fluid is characterized by being continuously filled without interruption with the one end side thrust dynamic pressure bearing portion, the other end side thrust dynamic pressure bearing portion, and the capillary seal portion.

  The fluid dynamic bearing device according to the example of the present invention can ensure the joining strength and the bending strength, and further the rigidity of the fluid dynamic bearing by ensuring the joint length between the constituent members sufficiently long.

  In addition, the hydrodynamic bearing device can be reduced in thickness.

  Hereinafter, embodiments of a hydrodynamic bearing device according to the present invention will be described in accordance with an assembling procedure with reference to the drawings. Although this embodiment is configured as a disk drive device that rotationally drives a disk such as a hard disk, the fluid dynamic bearing device according to the present invention is applicable as a fluid dynamic bearing device for various devices other than the disk drive device. Is.

  1 and 2, reference numeral 1 denotes a shaft member, and reference numeral 2 denotes a sleeve. The shaft member 1 includes a central shaft 11 and a rotating body 25 joined to one end portion (upper end portion in the drawing) of the central shaft 11 by press fitting or the like. In this embodiment, the rotating body 25 is a hub that rotates with a disk placed thereon. The entire circumference of the joint between the central shaft 11 and the rotating body 25 is welded or sealed with a sealing material so that a lubricating fluid described later does not leak to the outside.

  The sleeve 2 has a cylindrical portion 21 for forming the radial dynamic pressure bearing portions 3, 3 and a protruding portion 22 for forming the thrust dynamic pressure bearing portions 4, 5 formed on the outer peripheral side of the cylindrical portion 21. Do it. The protruding portion 22 is formed as a flange portion of the cylindrical portion 21 at one end portion (upper end portion in the drawing) of the cylindrical portion 21. In the illustrated example, the protruding portion 22 is integrally formed with the cylindrical portion 21 of the sleeve 2. However, the protruding portion 22 may be a separate member from the sleeve 2 and may be provided integrally with the cylindrical portion 21 of the sleeve 2 by press fitting or the like. . The protrusion 22 is a thrust plate for a thrust bearing. In a state where the protruding portion 22 is provided integrally with the cylindrical portion 21 of the sleeve 2, a radial dynamic pressure generating groove is formed on the inner peripheral surface of the cylindrical portion 21 of the sleeve 2, and the upper and lower surfaces of the protruding portion 22 are formed. In addition, a thrust dynamic pressure generating groove is formed. The radial dynamic pressure generating grooves are formed over the entire circumference at two locations on the inner circumferential surface of the cylindrical portion 21 as usual. The thrust dynamic pressure generating groove is also formed over the entire circumference of the upper and lower surfaces of the protrusion 22.

  The central shaft 11 of the shaft member 1 is inserted into the cylindrical portion 21 of the sleeve 2 from above. Next, a ring-shaped thrust receiving member 27, which is an annular member, is inserted along the outer periphery from the lower side and joined to the inner peripheral surface of the circular jetty 23 formed on the lower surface of the rotating body 25. Further, the joint between the jetty 23 and the thrust receiving member 27 is sealed with an adhesive or the like so that a lubricating fluid described later does not leak. Next, the cap-shaped cover 28 is put on the lower end portion of the central shaft 11, and the outer peripheral portion of the cover 28 is dropped into the lower peripheral groove of the cylindrical portion 21 and joined, and sealed with an adhesive 29 or the like.

  As shown in FIG. 1, between the inner peripheral surface of the thrust receiving member 27 and the outer peripheral surface of the sleeve 2 facing the thrust receiving member 27, between the upper surface of the thrust receiving member 27 and the lower surface of the protruding portion 22 facing the thrust receiving member 27. , Between the outer peripheral surface of the projecting portion 22 and the peripheral wall surface of the peripheral wall portion of the rotating body 25 facing the outer surface, and between the bowl-shaped inner peripheral portion 26 of the rotating body 25 and the upper surface of the projecting portion 22 facing the same. A gap is formed between the inner peripheral surface of the sleeve 2 and the outer peripheral surface of the central shaft 11 and between the cover 28 and the lower end portion of the central shaft 11. These gaps communicate with each other in the above order, and the gap between the inner circumferential surface of the thrust receiving member 27 and the outer circumferential surface of the sleeve 2 facing the opening is opened downward. Further, the outer peripheral surface of the sleeve 2 facing the inner peripheral surface of the thrust receiving member 27 is a tapered portion whose outer diameter decreases toward the bottom, and the inner peripheral surface of the thrust receiving member 27 A gap between the sleeve 2 and the outer peripheral surface is a capillary seal portion 45 in which the gap gradually increases downward. The capillary seal portion 45 is provided such that a liquid level A of a lubricating fluid (oil) described later is located.

  Lubricating fluid (oil) is injected from the capillary seal portion 45 into the gap. This injection method is arbitrary. For example, the gap may be injected in a vacuum state or a negative pressure state. A lower thrust dynamic pressure bearing portion 5, which is the other end side thrust dynamic pressure bearing portion, is formed between the upper surface of the thrust receiving member 27 and the lower surface of the protruding portion 22 facing the thrust receiving member 27. An upper thrust dynamic pressure bearing portion 4 which is one end side thrust dynamic pressure bearing portion is formed between the inner peripheral portion 26 and the upper surface of the projecting portion 22 opposed to the inner peripheral portion 26, and the inner peripheral surface of the sleeve 2 and the central axis Radial dynamic pressure bearing portions 3 and 3 are formed at two locations on the upper and lower sides between the outer peripheral surfaces of the eleventh. The lubricating fluid is interposed between the upper and lower thrust dynamic pressure bearing portions 4 and 5 and the radial dynamic pressure bearing portions 3 and 3.

  Next, in order to prevent the lubricating fluid indicated by the liquid level A from leaking to the outside, the oil absorbing cloth 30 is pressed and fixed to the lower surface of the thrust receiving member 27 by the cover plate 31. The cover plate 31 has an L-shaped cross section and is a ring-shaped member as a whole, and its rising portion is joined and fixed to the outer peripheral surface of the jetty 23 of the rotating body 25. The inner peripheral surface of the oil absorbing cloth 30 faces the opening of the capillary seal portion 45. Next, the rotor magnet 40 is bonded and fixed to the inner peripheral surface of the outer peripheral wall 41 of the rotating body 25. This completes the bearing set.

  In a separate process, a wire is wound around the stator core 35 to form a drive coil 36, and a core winding group is created. In yet another step, the insulating paper 38 is bonded to the bottom surface of the recess 334 of the base plate 33. The base plate 33 has a central hole, a jetty 333 around the central hole, and the concave portion 334 having a circumferential groove shape on the outer peripheral side of the jetty 333. A flexible circuit board 42 is also bonded to the base plate 33 along the bottom surface thereof as shown in FIG.

  The core winding set is bonded and fixed to the base plate 33. Here, the center hole of the stator core 35 is fitted along the outer peripheral surface of the jetty 333, and a step portion is formed on the outer peripheral side of the jetty 333, so that the stator core 35 is placed on and attached to the step portion. . Next, the terminal of the drive coil 36 is soldered to a predetermined circuit pattern on the flexible circuit board 42. This completes the stator assembly. Further, the bearing set is joined to the stator set. More specifically, the lower end portion of the cylindrical portion 21 of the sleeve 2 constituting a part of the bearing set is press-fitted from the upper side into the center hole of the base plate 33 constituting a part of the stator set and fixed. Thus, a hydrodynamic bearing motor for driving the disk rotation is completed. The base plate 33 is formed with holes for pulling out the flexible circuit board 42 and holes for escaping from the soldered portion, and these holes are sealed with an adhesive or other appropriate sealing material 43.

  By switching and controlling the energization to the drive coil 36 of the dynamic pressure bearing motor, the magnetic attraction and repulsive force between the salient poles of the stator core 35 and the rotor magnet 40 includes the rotor magnet 40, the rotating body 25, and the central shaft 11. The shaft member 1 and the thrust receiving member 27 are rotationally driven. By this rotation, a thrust dynamic pressure is generated in the lubricating fluid existing in the thrust dynamic pressure bearing portions 4 and 5, and a radial dynamic pressure is generated in the lubricating fluid existing in the radial dynamic pressure bearing portions 3 and 3. The member 1 rotates relative to the sleeve 2 while maintaining a non-contact state.

  In this way, the flange-shaped inner peripheral portion 26 and the thrust receiving member 27 of the rotating body 25 constituting a part of the shaft member 1 are located on the outer peripheral side with respect to the central shaft 11 constituting a part of the shaft member 1. Therefore, the outer peripheral part which surrounds the protrusion part 22 of the sleeve 2 is comprised. A radial dynamic pressure bearing portion 3 is formed between the outer peripheral surface of the central shaft 11 and the inner peripheral surface of the cylindrical portion 21 of the sleeve 2, and the protruding portion 22 of the sleeve 2 and the shaft member 1 are opposed in the axial direction. Thrust dynamic pressure bearing portions 4 and 5 are formed between the surfaces.

  According to the embodiment described above, the protruding portion 22 of the sleeve 2 corresponding to the thrust plate, the thrust receiving member 27 corresponding to the counter plate, and the capillary seal portion 45 are arranged on the radially outer side than the radial bearing portion 3. Therefore, the following effects can be obtained. Since the axial width of the radial bearing portion 3 can be sufficiently widened, the bearing rigidity can be increased, and a hydrodynamic bearing device with higher accuracy and less deterioration in rotational performance due to disturbance can be obtained. Can do. Since the length of the capillary seal portion 45 in the axial direction can be sufficiently long, it is possible to prevent depletion of the lubricating fluid due to evaporation, and to obtain a hydrodynamic bearing device with a long life and high reliability. it can. Since the axial dimensions of the parts sufficient to obtain the necessary joint strength between the members can be ensured, damage to the bearing due to external forces such as impact can be prevented. Since a space for installing the lubricating fluid absorbing member 30 can be secured, contamination due to leakage of the lubricating fluid can be prevented.

  A member in which the thrust bearing is integrated with the radial bearing, specifically, a protruding portion 22 for forming the thrust dynamic pressure bearing portions 4 and 5, and a cylinder for forming the radial dynamic pressure bearing portion 3 on the inner peripheral surface. Since the sleeve 2 integrated with the portion 21 is used and a thrust dynamic pressure generating groove and a radial dynamic pressure generating groove are formed in the sleeve 2, the axial dimension of the protrusion 22 for generating the thrust dynamic pressure is as follows. In addition, the diameter can be reduced, and the loss torque of the bearing can be reduced to reduce the power consumption. Further, since the thrust dynamic pressure generating groove and the radial dynamic pressure generating groove can be formed in the sleeve 2, the perpendicularity of the thrust bearing surface with respect to the radial bearing surface can be finished with high accuracy, and the rotational performance is improved.

  Since the capillary seal portion 45 is formed long in the axial direction between the inner peripheral surface of the thrust receiving member 27 and the outer peripheral surface of the cylindrical portion 21 of the sleeve 2, the lubricating fluid is less likely to scatter due to the centrifugal force. Thus, contamination by the lubricating fluid is prevented. In addition, there is a margin in the space in the axial direction, a space for arranging the lubricating fluid absorbing member can be easily secured, leakage of the lubricating fluid can be prevented, and surrounding contamination can be prevented. The thrust bearing portion 5 formed between the opposed surfaces of the protruding portion 22 of the sleeve 2 and the thrust receiving member is formed on the radially outer side than the radial bearing portions 3 and 3 formed on the cylindrical portion 21 of the sleeve 2. Therefore, an increase in the axial dimension of the hydrodynamic bearing device due to the formation of the thrust bearing portion 5 can be prevented.

  The hydrodynamic bearing device according to the present invention can be applied not only to the outer rotor type motor as described above but also to an inner rotor type motor. FIG. 3R> 3 shows an embodiment in which the hydrodynamic bearing device according to the present invention is applied to an inner rotor type motor. Constituent parts that are the same as or corresponding to those of the above-described embodiment or common constituent parts are denoted by common reference numerals, and constituent parts that are different from those of the above-described embodiment are described mainly.

  The embodiment shown in FIG. 3 is significantly different from the above embodiment in that the cylindrical peripheral wall 50 of the rotating body 25 for attaching the rotor magnet 40 is in the intermediate portion in the radial direction of the rotating body 25. The rotor magnet 40 is fixed to the outer peripheral surface of the peripheral wall 50, and the inner peripheral surface of the stator core 35 faces the outer peripheral surface of the rotor magnet 40 with an appropriate gap. The stator core 35 has an outer peripheral side fixed to a step portion of the base plate 33, and a drive coil 36 is wound around each inwardly facing salient pole.

  Other configurations are almost the same as those of the above-described embodiment. Reference numeral 1 is a shaft member, 2 is a sleeve, 3 is a radial dynamic pressure bearing, 4 and 5 are thrust dynamic pressure bearings, 11 is a central shaft, 21 is a cylindrical portion, 22 Denotes a protruding portion, 27 denotes a thrust receiving member, 30 denotes an oil absorbing cloth, and 45 denotes a capillary seal portion. A cover 48 is fitted and sealed at the lower end of the cylindrical portion 21 to prevent the lubricating oil from leaking. As shown in FIG. 3, even when the hydrodynamic bearing device according to the present invention is applied to an inner rotor type motor, the same effect as that of the above embodiment can be obtained.

  In any embodiment, the oil absorbing cloth 30 may be attached to the base plate 33 side. The dynamic pressure bearing device according to the present invention can be used not only as a disk drive motor but also as a bearing device for various rotating bodies.

  According to the present invention, the sleeve has a cylindrical portion for forming the radial dynamic pressure bearing portion, and a protrusion for forming the thrust dynamic pressure bearing portion formed on the outer peripheral side of the cylindrical portion, and the shaft member is A radial dynamic pressure bearing having a central shaft inserted into the cylindrical portion of the sleeve and an outer peripheral portion surrounding the protruding portion of the sleeve, and between the outer peripheral surface of the central shaft and the inner peripheral surface of the cylindrical portion of the sleeve And the thrust dynamic pressure bearing portion is formed between the axially facing surfaces of the protruding portion of the sleeve and the shaft member, so that the radial width of the radial bearing portion can be sufficiently wide. it can. As a result, the bearing rigidity can be increased, and a hydrodynamic bearing device can be obtained with higher accuracy and less deterioration in rotational performance due to disturbance. Since the axial dimensions of the parts sufficient to obtain the necessary joint strength between the members can be ensured, damage to the bearing due to external forces such as impact can be prevented.

  Further, since the thrust bearing portion formed between the facing surfaces of the flange portion and the thrust receiving member is formed on the radially outer side than the radial bearing portion formed in the cylindrical portion, the thrust bearing portion 5 is formed. Accordingly, an increase in the axial dimension of the hydrodynamic bearing device can be prevented.

  Further, the thrust bearing portion is filled with a lubricating fluid, and a tapered portion where the distance between the outer peripheral surface of the sleeve and the inner peripheral surface of the thrust receiving member gradually increases is provided on the outer side in the axial direction from the thrust dynamic pressure bearing portion. Since the capillary seal portion for preventing leakage of the lubricating fluid is constituted by the tapered portion, it is possible to prevent an increase in the axial dimension of the dynamic pressure bearing device due to the formation of the thrust bearing portion. In addition, since the length of the capillary seal portion in the axial direction can be sufficiently long, it is possible to prevent depletion of the lubricating fluid due to evaporation, and to obtain a highly reliable hydrodynamic bearing device having a long life. it can.

  Further, the hydrodynamic bearing device is a hydrodynamic bearing device of a disc drive device, and the rotating body is a disc mounting hub, so that a disc drive device having the above advantages can be obtained.

It is an expansion front sectional view of the principal part showing an embodiment of a fluid dynamic bearing device concerning the present invention. It is front sectional drawing which shows the said embodiment. It is front sectional drawing which shows another embodiment of the fluid dynamic bearing apparatus concerning this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Shaft member 2 Sleeve 3 Radial dynamic pressure bearing part 4 Thrust dynamic pressure bearing part 5 Thrust dynamic pressure bearing part 11 Center shaft 21 Cylindrical part 22 Protrusion part 25 Rotating body 27 Thrust receiving member as outer peripheral part 45 Capillary seal part

Claims (9)

A cylindrical sleeve;
A shaft member having an outer peripheral surface facing the inner peripheral surface of the sleeve, and rotating relative to the sleeve about a rotation center axis;
A radial dynamic pressure bearing portion formed in a gap between the inner peripheral surface of the sleeve and the outer peripheral surface of the shaft member, and having a radial dynamic pressure generating groove array for inducing fluid dynamic pressure during the relative rotation;
One end side having a thrust dynamic pressure generating groove array that is formed in a gap between one axial end surface of the sleeve and the opposing surface of the shaft member facing the one end surface and induces fluid dynamic pressure during the relative rotation. A thrust hydrodynamic bearing,
A capillary seal that is formed in a gap between the sleeve and the shaft member facing the sleeve, and is connected to the one end side thrust dynamic pressure bearing portion, and the gap dimension increases as the distance from the one end side thrust dynamic pressure bearing portion increases. And
Lubricating fluid that fills the radial dynamic pressure bearing portion, the one end side thrust dynamic pressure bearing portion, and the capillary seal portion continuously without interruption, and forms a gas-liquid interface with the outside air only in the capillary seal portion. And a hydrodynamic bearing device.   The removal prevention mechanism for preventing the shaft member from coming off relative to the sleeve is formed between the one end side thrust dynamic pressure bearing portion and the capillary seal portion. 1. The hydrodynamic bearing device according to 1. An annular member is fixed to the shaft member so as to face the other end surface of the sleeve in the axial direction,
The hydrodynamic bearing device according to claim 1, wherein the capillary seal portion is formed between an outer peripheral surface of the sleeve and an inner peripheral surface of the annular member. An annular member is fixed to the shaft member so as to face the other end surface of the sleeve in the axial direction,
4. The hydrodynamic bearing device according to claim 2, wherein the slip-off prevention mechanism is configured by locking the other end surface of the sleeve and one end surface of the annular member. 5. The shaft member is formed with a peripheral wall portion surrounding a part of the outer peripheral portion of the sleeve, and a jetty portion protruding from the peripheral wall portion to the other end side,
The hydrodynamic bearing device according to claim 3 or 4, wherein the annular member is fixed in contact with each of the peripheral wall portion and the jetty portion.   The hydrodynamic bearing device according to claim 3, wherein the annular member is fixed to the shaft body via an adhesive. The capillary seal portion is formed in a radial gap between the outer peripheral surface of the sleeve and the inner peripheral surface of the shaft member facing the outer peripheral surface,
The inclination angle of the outer peripheral surface of the sleeve constituting the capillary seal portion with respect to the rotation center axis is formed larger than the inclination angle of the inner peripheral surface of the shaft member constituting the capillary seal portion with respect to the rotation center axis. The hydrodynamic bearing device according to claim 1, wherein the hydrodynamic bearing device is provided. An outer peripheral portion on one end side of the sleeve is provided with a flange portion extending in the radial direction integrally or separately from the sleeve,
The said one end side thrust dynamic pressure bearing part is formed in the clearance gap between the one end surface of the said collar part, and the opposing surface of the said shaft member facing this one end surface. Any one of the hydrodynamic bearing devices. The other end side having a thrust dynamic pressure generating groove array for inducing fluid dynamic pressure at the time of the relative rotation in the gap between the other axial end surface of the sleeve and the opposing surface of the shaft member facing the other end surface A thrust hydrodynamic bearing is formed,
2. The lubricating fluid is continuously filled with the one end side thrust dynamic pressure bearing portion, the other end side thrust dynamic pressure bearing portion, and the capillary seal portion without interruption. The hydrodynamic bearing device according to any one of 8.

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