JP2007071312A - Dynamic pressure bearing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a dynamic pressure bearing device capable of fixing a thrust member and a shaft member powerfully without reducing rigidity of a bearing. <P>SOLUTION: Chamfers 9e, 9h and a large diameter inner peripheral face 9f are provided at one end of the inner periphery of the thrust member 9, and a space as an adhesive accumulation part is formed between the large diameter inner peripheral face and an outer peripheral face of the shaft member 2. Consequently, since sufficient volume of adhesive can be kept between an inner peripheral face of the thrust member and the outer peripheral face of the shaft member, strength of adhesive bonding can be increased. Since the adhesive overflowing from the adhesive accumulation part is kept in a space among the chamfers and the outer peripheral face of the shaft member, it is possible to prevent adhesive from going around onto one end face of the thrust member which becomes a thrust bearing face and avoid a defect such as reduction of performance of the thrust bearing. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a hydrodynamic bearing device.

  The dynamic pressure bearing device is a bearing device that generates a dynamic pressure action on a lubricating fluid (for example, lubricating oil) filled in a bearing gap and supports a shaft member with this pressure. This hydrodynamic bearing device has features such as high-speed rotation, high rotation accuracy, and low noise. Information equipment such as magnetic disk devices such as HDD, CD-ROM, CD-R / RW, DVD-ROM / For small motors such as optical disk devices such as RAM, spindle motors for disk drives in magneto-optical disk devices such as MD and MO, polygon scanner motors for laser beam printers (LBP), color wheel motors for projectors, and axial fans. It is suitable as a bearing device.

As this type of hydrodynamic bearing device, for example, Patent Document 1 shows an example in which a thrust plate for sealing both end openings of a sleeve is attached to a journal (shaft). The thrust plate forms a second gap serving as a thrust bearing gap between the thrust plate and the radially extending surface of the small inner diameter portion of the sleeve.
6-54916

  In the dynamic pressure bearing device as described above, the means for attaching the thrust plate to the journal uses an adhesive such as adhesion or press-fitting under the presence of an adhesive (hereinafter referred to as press-fit adhesion) in view of the fixing force. Those are preferred. As described above, when fixing using an adhesive, it is necessary to uniformly apply the adhesive to the fixing surface. However, there is a very small gap between the outer peripheral surface of the journal and the inner peripheral surface of the thrust plate, or a negative gap to obtain pressure input, and an appropriate amount of adhesive is uniformly applied to such a portion. It is extremely difficult to do. If the application amount of the adhesive is too large, excess adhesive is pushed out and wraps around one end surface of the thrust plate as the thrust plate is pushed in the axial direction. Since one end surface of the thrust plate acts as a thrust bearing surface, the thrust bearing gap cannot be set to the specified width due to the wraparound adhesive, or the dynamic pressure groove facing the thrust bearing gap is filled with adhesive, The bearing performance in the direction may be adversely affected. On the other hand, if the application amount of the adhesive is too small, a sufficient fixing force between the journal and the thrust plate cannot be obtained, and the thrust plate may fall off due to an impact load or the like.

  An object of the present invention is to provide a hydrodynamic bearing device in which a thrust member and a shaft member are firmly fixed without deteriorating bearing performance.

  In order to solve the above-mentioned problems, a hydrodynamic bearing device according to the present invention includes a shaft member, a bearing member in which a shaft member is inserted into an inner periphery, and an outer peripheral surface of the shaft member fixed by adhesion, and a chamfer is formed at one end of the inner periphery. And a thrust bearing portion that supports the shaft member in the thrust direction by dynamic pressure action of a lubricating fluid generated in a thrust bearing gap between one end surface of the thrust member and the end surface of the bearing sleeve facing the thrust member. In the hydrodynamic bearing device provided, an adhesive reservoir that leads to a space between the chamfer of the thrust member and the outer peripheral surface of the shaft member is formed between the outer peripheral surface of the shaft member and the inner peripheral surface of the thrust member. .

  In this way, by forming an adhesive reservoir that leads to the space between the chamfer of the thrust member and the outer peripheral surface of the shaft member between the outer peripheral surface of the shaft member and the inner peripheral surface of the thrust member, It becomes possible to hold a sufficient volume of adhesive between the outer peripheral surface and the inner peripheral surface of the thrust member. Thereby, the adhesive strength of the thrust member can be increased, and the thrust member can be reliably prevented from falling off the shaft member due to impact load or the like. When the shaft member is inserted into the inner periphery of the thrust member, excess adhesive overflowed as the shaft member is pushed in is trapped in the adhesive reservoir, and further excess adhesive is separated from the chamfer and the outer peripheral surface of the shaft member. Since it is held in the space (first space) between them, excess adhesive does not go around to one end face of the thrust member, and it is possible to surely prevent deterioration of bearing performance due to entry of the adhesive into the thrust bearing surface. Can do. Due to such an adhesive reservoir and further, an adhesive capturing function by the first space, variation in the amount of adhesive applied is allowed, and the adhesive application process can be simplified. The bearing surface here means a surface facing the bearing gap, and it does not matter whether a dynamic pressure generating portion such as a dynamic pressure groove is formed on this surface (the same applies to the following description). ).

  If only the space volume for holding the adhesive is increased, it can be coped with, for example, by increasing the chamfering depth of the chamfer. However, when the chamfering depth is increased in this way, the area of one end surface of the thrust member that becomes the thrust bearing surface is reduced, which may adversely affect the bearing performance, particularly in the thrust direction. On the other hand, in the present invention, since the chamfer chamfering depth is not affected, this type of problem can be avoided.

  The adhesive reservoir described above may be formed on either the shaft member side or the thrust member side. For example, when provided on the thrust member side, if a small-diameter inner peripheral surface and a large-diameter inner peripheral surface connected to the chamfer are provided on the inner peripheral surface of the thrust member, the large-diameter inner peripheral surface and the outer peripheral surface of the shaft member An adhesive reservoir can be formed.

  In this case, it is desirable to form the large diameter inner peripheral surface in a cylindrical surface. If the large-diameter inner peripheral surface is a cylindrical surface, when the shaft member is inserted into the thrust member, (1) first, alignment with the shaft member is performed by taper guide in the thrust member chamfer, and (2) then large The centering of both the inner peripheral surface and the outer peripheral surface of the shaft member is performed by fitting between the cylindrical surfaces. Therefore, even if the shaft member is pushed forward thereafter, the coaxiality of the shaft member and the thrust member does not go out of alignment, and the centering can be reliably performed between both members. For this reason, it is possible to prevent the thrust support force from being lowered and the thrust member to be worn at an early stage due to the perpendicularity between the shaft member and the thrust member.

  When the seal space is formed on the outer periphery of the thrust member, if the perpendicularity between the thrust member and the shaft member is insufficient, the seal space may be unbalanced and oil leakage may occur. In this case, as described above, a high squareness is ensured between the two members, so that such a problem can be prevented.

  The motor comprising the hydrodynamic bearing device, the stator coil, and the rotor magnet described above is manufactured at a low cost and has a high rotational accuracy.

  As described above, according to the present invention, it is possible to provide a dynamic pressure bearing device in which the thrust member and the shaft member are strongly fixed without deteriorating the bearing performance.

  Hereinafter, a first embodiment of the present invention will be described with reference to FIGS.

  FIG. 1 conceptually shows one configuration example of a spindle motor for information equipment incorporating a fluid dynamic bearing device (fluid fluid dynamic bearing device) 1 according to a first embodiment of the present invention. This spindle motor for information equipment is used in a disk drive device such as an HDD, and includes a dynamic pressure bearing device 1, a rotor (disk hub) 3 attached to a shaft member 2 of the dynamic pressure bearing device 1, and a radius, for example. A stator coil 4a and a rotor magnet 4b that are opposed to each other with a gap in the direction, and a bracket 5 are provided. The stator coil 4 a is attached to the outer periphery of the bracket 5, and the rotor magnet 4 b is attached to the inner periphery of the disk hub 3. The disk hub 3 holds one or more disks D such as magnetic disks on the outer periphery thereof. When the stator coil 4a is energized, the rotor magnet 4b is rotated by an electromagnetic force generated between the stator coil 4a and the rotor magnet 4b, and the disk hub 3 and the shaft member 2 are rotated together therewith.

  FIG. 2 is a sectional view showing the hydrodynamic bearing device 1 used in the spindle motor. The hydrodynamic bearing device 1 includes a shaft member 2, a bearing member 6, and two thrust members fixed on the outer peripheral surface of the shaft member 2 in the axial direction (the first thrust member 9 on the upper side and the first thrust member 9 on the lower side). The second thrust member 10) is configured as a main component. In this embodiment, the case where the bearing member 6 is comprised with the housing 7 and the bearing sleeve 8 fixed to the inner periphery of the housing 7 is illustrated. In addition, the upper side said here refers to the side from which the edge part of the shaft member 2 protrudes from the opening part of the housing 7, and the lower side refers to the axial direction opposite side, and it is the same also in the following description.

  Between the inner peripheral surface 8a of the bearing sleeve 8 and the outer peripheral surface 2a of the shaft member 2, the first radial bearing portion R1 and the second radial bearing portion R2 are provided apart from each other in the axial direction. A first thrust bearing portion T1 is provided between the upper end face 8b of the bearing sleeve 8 and the lower end face 9b of the first thrust member 9, and the lower end face 8c of the bearing sleeve 8 and the upper side of the second thrust member 10 are provided. A second thrust bearing portion T2 is provided between the end surface 10b.

  The shaft member 2 is made of a metal material such as stainless steel, or has a hybrid structure of metal and resin. The shaft member 2 as a whole has a shaft shape with substantially the same diameter, and an intermediate portion is formed with a relief portion 2b formed to have a slightly smaller diameter than other portions. A concave portion, for example, a circumferential groove 2c is formed at a fixed position of the first and second thrust members 9 and 10 on the outer peripheral surface 2a of the shaft member 2.

  The housing 7 is formed in a cylindrical shape by, for example, injection molding of a resin material, and the inner peripheral surface 7a is a straight cylindrical surface having the same diameter. The outer peripheral surface of the housing 7 is fixed to the inner peripheral surface of the bracket 5 shown in FIG. 1 by means such as press-fitting, bonding, and press-fitting adhesion.

  The resin forming the housing 7 is mainly a thermoplastic resin. For example, as an amorphous resin, polysulfone (PSF), polyethersulfone (PES), polyphenylsulfone (PPSF), polyetherimide (PEI) As the crystalline resin, liquid crystal polymer (LCP), polyether ether ketone (PEEK), polybutylene terephthalate (PBT), polyphenylene sulfide (PPS), or the like can be used. The type of filler to be filled in the resin is not particularly limited. For example, as the filler, fibrous filler such as glass fiber, whisker-like filler such as potassium titanate, and scaly filler such as mica. A fibrous or powdery conductive filler such as carbon fiber, carbon black, graphite, carbon nanomaterial, or metal powder can be used. These fillers may be used alone or in combination of two or more. In this embodiment, as a material for forming the housing 7, a resin material in which 2 to 8 wt% of a carbon fiber or a carbon nanotube as a conductive filler is mixed with a liquid crystal polymer (LCP) as a crystalline resin is used.

  In addition, the housing 7 can be formed of a metal material (for example, a soft metal material such as brass) or other materials. Further, as one aspect of injection molding, injection molding or MIM molding of a low melting point metal (such as an aluminum alloy) can be employed. The processing method of the housing 7 is not limited to the method illustrated above, For example, the housing 7 can also be formed by turning.

  The bearing sleeve 8 is formed in a cylindrical shape, for example, a porous body made of sintered metal, particularly a sintered metal porous body mainly composed of copper, and is press-fitted into a predetermined position on the inner peripheral surface 7a of the housing 7. It is fixed by means such as adhesion or press-fit adhesion. The bearing sleeve 8 can be formed of a metal material such as a copper alloy in addition to the sintered metal.

  The inner peripheral surface 8a of the bearing sleeve 8 is provided with two upper and lower regions that are the dynamic pressure generating portions of the first radial bearing portion R1 and the second radial bearing portion R2, and are separated from each other in the axial direction. For example, herringbone-shaped dynamic pressure grooves 8a1 and 8a2 as shown in FIG. The upper end surface 8b of the bearing sleeve 8 is provided with a region serving as a dynamic pressure generating portion of the first thrust bearing portion T1, and this region has a spiral dynamic pressure groove 8b1 as shown in FIG. Is formed. Similarly, a region serving as a dynamic pressure generating portion of the second thrust bearing portion T2 is provided on the lower end surface 8c of the bearing sleeve 8, and a spiral dynamic pressure as shown in FIG. 3C is provided in this region. A groove 8c1 is formed.

  Each of the first thrust member 9 and the second thrust member 10 is formed of a soft metal material such as brass (brass), other metal materials, or a resin material in the same ring shape, and the outer peripheral surface of the shaft member 2 2a is fixed at a predetermined position. In consideration of the fixing force, the fixing method is preferably one using an adhesive such as adhesion or press-fit adhesion. In this embodiment, the case of fixing by press-fitting adhesion is illustrated.

  Hereinafter, the shape of the first thrust member 9 will be described with reference to FIGS. 4 and 5. 4 is an enlarged cross-sectional view of the first thrust member 9 and its periphery in FIG. 2, and FIG. 5 is an enlarged view of a portion A in FIG. The first thrust member 9 has, in order from the side facing the upper end surface 8b of the bearing sleeve 8, a first chamfer 9e, a cylindrical large-diameter inner peripheral surface 9f, a tapered portion 9g, and a cylindrical small-diameter inner surface. A peripheral surface 9d and a second chamfer 9h are provided. The first chamfer 9e has a tapered shape that gradually increases in diameter downward, the upper end is connected to the lower end of the large-diameter inner peripheral surface 9f, and the lower end reaches the lower end surface 9b. The taper portion 9g is similarly tapered and gradually increases in diameter downward, and is interposed between the large-diameter inner peripheral surface 9f and the small-diameter inner peripheral surface 9d. The large-diameter inner peripheral surface 9f has an inner diameter that is slightly larger than the outer diameter of the shaft member 2, and the small-diameter inner peripheral surface 9d has an inner diameter that is smaller than the outer diameter of the shaft member 2 by the press-fitting allowance. Have dimensions. From the above configuration, a tapered first space S3 is formed between the first chamfer 9e and the outer peripheral surface 2a of the shaft member 2 so that the gap width decreases toward the top. A second space S4 having a uniform width is formed between the large-diameter inner peripheral surface 9f and the outer peripheral surface 2a of the shaft member 2, and the second space S4 functions as an adhesive reservoir as will be described later. Play.

  On the inner peripheral surface of the second thrust member 10, similarly to the first thrust member 9, in order from the side facing the lower end surface 8 c of the bearing sleeve 8, a first chamfer 10 e, a large-diameter inner peripheral surface 10 f, and a tapered portion (Reference numerals are omitted), a small-diameter inner peripheral surface 10d, and a second chamfer 10h are formed (see FIG. 2). A first space S5 is formed between the first chamfer 10e and the outer peripheral surface 2a of the shaft member 2, and a second space S6 is formed between the large-diameter inner peripheral surface 10f and the outer peripheral surface 2a of the shaft member 2. . Since the shape and dimensional relationship of each part are in accordance with the description of the first thrust member 9, repeated description and enlarged drawings are omitted. The second thrust member 10 has the same shape as the first thrust member 9. When the first thrust member 9 is turned upside down and attached to the shaft member 2, the second thrust member 10 becomes the second thrust member 10.

  The outer peripheral surface 9 a of the first thrust member 9 forms a first seal space S 1 having a predetermined volume with the inner peripheral surface 7 a of the upper end opening of the housing 7, and the outer peripheral surface 10 a of the second thrust member 10. Forms a second seal space S2 having a predetermined volume with the inner peripheral surface 7a of the lower end opening of the housing 7. In this embodiment, the outer peripheral surface 9a of the first thrust member 9 and the outer peripheral surface 10a of the second thrust member 10 are each formed in a tapered surface shape that is gradually reduced in diameter toward the opening side of the housing. Therefore, both the seal spaces S1 and S2 have a tapered shape that is gradually reduced in the direction of approaching each other. When the shaft member 2 is rotated, the lubricating oil in both the seal spaces S1 and S2 is drawn in a direction in which the seal space is narrowed by a drawing action by a capillary force and a drawing action by a centrifugal force at the time of rotation. Thereby, the leakage of the lubricating oil from the inside of the housing 7 is effectively prevented. In order to prevent oil leakage more reliably, the upper end surface 7b and the lower end surface 7c of the housing 7, the upper end surface 9c of the first thrust member 9, and the lower end surface 10c of the second thrust member 10 are respectively coated with an oil repellent coating. It can also be formed.

  The first and second seal spaces S <b> 1 and S <b> 2 have a buffer function that absorbs a volume change amount associated with a temperature change of the lubricating oil filled in the internal space of the housing 7. Within the assumed temperature change range, the oil level is always in both seal spaces S1, S2. In order to achieve this, the sum of the volumes of both the seal spaces S1, S2 is set to be larger than at least the volume change amount associated with the temperature change of the lubricating oil filled in the internal space.

  As described above, when the first and second thrust members 9 and 10 are arranged at both ends of the housing 7, the total sum of the seal space is larger than the case where the thrust members are arranged only at one end, so that the buffer function of the lubricating oil is increased. Can be increased. Therefore, since the axial dimension of the first and second thrust members 9 and 10 can be reduced, the axial dimension of the entire bearing can be reduced. Alternatively, if the axial dimension of the bearing sleeve is increased by the axial dimension reduction of the thrust member without changing the axial dimension of the entire bearing, and the axial distance between the first and second radial bearing portions R1 and R2 is increased. The load capacity against moment load can be increased.

Here, the process of attaching the first thrust member 9 to the shaft member 2 will be described with reference to FIG.
(1) An adhesive is applied to the position on the outer peripheral surface 2a of the shaft member 2 where the first thrust member 9 is fixed. As this adhesive, for example, a thermosetting adhesive can be used.
(2) The shaft member 2 is inserted into the inner periphery of the first thrust member 9 from the first chamfer 9e side. When the first chamfer 9e of the first thrust member 9 is inserted in a direction that is forward in the insertion direction, the shaft member 2 and the thrust member 9 are aligned by the guide of the first chamfer 9e and inserted smoothly. .
(3) The insertion is advanced to fit the large-diameter inner peripheral surface 9f of the first thrust member 9 and the outer peripheral surface 2a of the shaft member 2 (see FIG. 6A). By this fitting, the shaft member 2 and the first thrust member 9 are centered. With this centering, even if the insertion of the shaft member 2 is advanced, the coaxiality of the shaft member 2 and the first thrust member 9 does not go out of alignment, and the centering can be reliably performed between both members.
(4) When the insertion is further advanced, the shaft member 2 is press-fitted into the small-diameter inner peripheral surface 9d of the first thrust member 9 (see FIG. 6B). At this time, it is guided by the taper portion 9g, and the press-fitting can be started smoothly.
(5) When the press-fitting is advanced, the application region of the adhesive G on the outer peripheral surface 2a of the shaft member 2 enters the region facing the small-diameter inner peripheral surface 9d of the first thrust member 9, and the first thrust member 9 An adhesive G is interposed between the surface 9 d and the outer peripheral surface 2 a of the shaft member 2. At this time, the excess adhesive G that protrudes is held in the second space S4 as an adhesive reservoir, and further excess adhesive G is held in the first space S3 (see FIG. 6C). Thus, when the first thrust member 9 is press-fitted to a predetermined position on the outer peripheral surface 2a of the shaft member 2, the excessive adhesive G is held in the second space S4 and the first space S3 (FIG. 6). d).

  The second thrust member 10 is inserted from below the shaft member 2 in the same manner as the first thrust member 9, and is press-fitted and fixed at a predetermined position. At this time, all excess adhesive is held in the second space S6 as an adhesive reservoir, and further in the first space S5 (not shown). After the first thrust member 9 and the second thrust member 10 are inserted to a predetermined position, the shaft member 2 is heated (baked) to cure the adhesive, and both thrust members are securely fixed to the shaft member 2. can do. At this time, the adhesive applied to the shaft member 2 is retained and solidified in the circumferential groove 2c as the adhesive reservoir, the second space S4 (S6), and the first space S3 (S5), so that the thrust member The adhesive strength to the shaft member 2 of 9, 10 is improved.

  By the way, if only the space volume for holding the adhesive is increased, for example, it can be coped with by increasing the chamfering depth of the first chamfer (shown by a dotted line in FIG. 7). However, when the chamfering depth of the first chamfer 9e is increased in this way, the area of the lower end surface 9b of the first thrust member 9 serving as the thrust bearing surface is reduced, which may adversely affect the bearing performance in the thrust direction. . In the present invention, since the chamfering depth of the first chamfer 9e is not affected, such a problem can be avoided (the same applies to the second thrust member 10).

  As described above, by forming the second space S4 as an adhesive reservoir between the large-diameter inner peripheral surface 9f of the first thrust member 9 and the outer peripheral surface 2a of the shaft member 2, an adhesive having a sufficient volume is formed. Can be held. Thereby, the adhesive strength between the first thrust member 9 and the shaft member 2 is increased, and the first thrust member 9 can be reliably prevented from falling off the shaft member 2 due to an impact load or the like. Moreover, since the overflowing adhesive G is held in the second space S4, and further in the first space S3 formed between the first chamfer 9e and the outer peripheral surface 2a of the shaft member 2, the adhesive G It is possible to reliably prevent the first thrust member 9 serving as the thrust bearing surface from entering the lower end surface 9b, and to prevent a decrease in bearing performance in the thrust direction. Due to such a function of capturing the adhesive G by the first and second spaces, the application amount of the adhesive G is allowed to vary, and the application process of the adhesive G can be simplified. Further, in the assembling process, since the centering of both members is performed by fitting the large-diameter inner peripheral surface 9f of the first thrust member 9 and the outer peripheral surface 2a of the shaft member 2, the shaft member 2 and the first thrust member It is possible to prevent problems such as a decrease in thrust support force, early wear of the thrust member, and a decrease in the sealing effect due to the perpendicularity defect 9 (the same applies to the second thrust member 10).

  As described above, after the thrust members 9 and 10 are fixed to the shaft member 2 with the bearing sleeve 8 interposed therebetween, this assembly is inserted into the inner peripheral surface 7a of the housing 7, and the outer peripheral surface of the bearing sleeve 8 is connected to the housing 7 The inner peripheral surface 7a is fixed. The bearing sleeve 8 can be fixed to the housing 7 by an appropriate means such as adhesion, press-fitting, press-fitting adhesion, welding (ultrasonic welding) or the like. When the assembly is completed in this way, the internal space of the housing 7 sealed with the first and second thrust members 9 and 10 is filled with, for example, lubricating oil as a lubricating fluid including the internal pores of the bearing sleeve 8.

  Lubricating oil is injected by, for example, immersing an unlubricated hydrodynamic bearing device in the lubricating oil in a vacuum chamber and then releasing it to atmospheric pressure. At this time, as shown in FIG. 1, since both ends of the housing 7 are open, the air in the internal space can be surely replaced with lubricating oil, compared with the case where one end of the housing is closed, Detrimental effects such as oil leakage at high temperatures can be reliably avoided. In addition to such a lubrication method using reduced pressure, lubrication under normal pressure (for example, pressurized lubrication of lubricating oil) is possible, and the lubrication device and process can be simplified to reduce manufacturing costs. it can.

  When the shaft member 2 rotates, a dynamic pressure of lubricating oil is generated in the radial bearing gap, and the shaft member 2 is supported in a non-contact manner in the radial direction by a lubricating oil film formed in the radial bearing gap. Thus, the first radial bearing portion R1 and the second radial bearing portion R2 that support the shaft member 2 in a non-contact manner so as to be rotatable in the radial direction are configured. At the same time, the dynamic pressure of the lubricating oil is generated in the thrust bearing gap, and the shaft member 2 and the thrust members 9, 10 are supported in a non-contact manner so as to be rotatable in the thrust direction by the lubricating oil film formed in the thrust bearing gap. . Thereby, the 1st thrust bearing part T1 and the 2nd thrust bearing part T2 which non-contact-support the shaft member 2 rotatably in a thrust direction are comprised.

  FIG. 8 shows a hydrodynamic bearing device 21 according to a second embodiment of the present invention. The hydrodynamic bearing device 21 is different from the hydrodynamic bearing device 1 according to the first embodiment in that the housing and the bearing sleeve are integrated and the bearing member 26 is a single component, so that the number of components and the number of assembly steps can be reduced. The cost is further reduced through reduction. The bearing member 26 can be formed by forging or machining a soft metal or other metal material, or can be formed by injection molding of a resin or a low melting point metal, or further by MIM molding.

  In this case, in the bearing member 26, the first and second radial bearing portions R1 and R2 are provided between the inner peripheral surface 28a of the sleeve portion 28 and the outer peripheral surface 2a of the shaft member 2, and the upper end surface of the sleeve portion 28 is provided. The first thrust bearing portion T1 is between the lower end surface 9b of the thrust member 9 and the second thrust bearing portion T2 is between the lower end surface 28c of the sleeve portion 28 and the upper end surface 10b of the thrust member 10. Provided. Further, a seal space is provided between the inner peripheral surface 27a of the opening at both ends of the bearing member 26 (both ends of the opening 27 of the portion 27 corresponding to the housing) and the outer peripheral surfaces 9a, 10a of the first and second thrust members 9, 10. S1 and S2 are formed.

  FIG. 9 shows a hydrodynamic bearing device 31 according to a third embodiment of the present invention. The hydrodynamic bearing device 31 is formed in a cup shape in which the lower opening of the housing 37 is sealed, and the thrust member 9 is provided only at one location on the outer peripheral surface 2 a of the shaft member 2. It differs from other embodiment by the point by which the flange part 2d is formed in the lower end. When the shaft member 2 rotates, a second thrust bearing portion T2 is formed between the upper end surface 2d1 of the flange portion 2d and the lower end surface 8c of the bearing sleeve 8.

  In the fluid dynamic bearing device 31 described above, the flange portion 2d of the shaft member 2 is not necessarily formed, and the shaft member 2 may have a straight shape. In this case, the shaft member 2 is supported in the thrust direction only by the first thrust bearing portion T1 formed between the lower end surface 9b of the first thrust member 9 and the upper end surface 8b of the bearing sleeve 8 (not shown).

It is sectional drawing which shows an example of the motor incorporating the dynamic pressure bearing apparatus. 1 is a cross-sectional view showing a fluid dynamic bearing device 1 according to a first embodiment of the present invention. (A) It is sectional drawing of the bearing sleeve 8. FIG. (B) (a) It is the top view seen from the b arrow direction in a figure. (C) (a) It is the top view seen from the c arrow direction in a figure. It is an expanded sectional view of the 1st thrust member 9 and its circumference. It is an enlarged view of the A part of FIG. FIG. 5 is a diagram illustrating an assembly process of the shaft member 2 and the first thrust member 9. It is a comparison figure of the thrust member concerning the present invention, and a conventional product. It is sectional drawing which shows the hydrodynamic bearing apparatus 21 concerning the 2nd Embodiment of this invention. It is sectional drawing which shows the hydrodynamic bearing apparatus 31 concerning the 3rd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Dynamic pressure bearing apparatus 2 Shaft member 3 Disc hub 4a Stator coil 4b Rotor magnet 5 Bracket 6 Bearing member 7 Housing 8 Bearing sleeve 9 First thrust member 9d Small diameter inner peripheral surface 9e First chamfer 9f Large diameter inner peripheral surface 9g Taper part 9h Second chamfer 10 Second thrust member G Adhesives R1, R2 Radial bearing T1, T2 Thrust bearing S1, S2 Seal space S3, S5 First space S4, S6 Second space (adhesive reservoir)

Claims (5)

A shaft member, a bearing member in which the shaft member is inserted on the inner periphery, a thrust member fixed to the outer peripheral surface of the shaft member by adhesion, and having a chamfer at one end of the inner periphery, and one end surface of the thrust member facing the thrust member In the hydrodynamic bearing device comprising a thrust bearing portion that supports the shaft member in the thrust direction by the hydrodynamic action of the lubricating fluid generated in the thrust bearing gap between the end surface of the bearing sleeve,
A hydrodynamic bearing device characterized in that an adhesive reservoir that leads to a space between a chamfer of a thrust member and an outer peripheral surface of the shaft member is formed between the outer peripheral surface of the shaft member and the inner peripheral surface of the thrust member.   The inner peripheral surface of the thrust member includes a small-diameter inner peripheral surface and a large-diameter inner peripheral surface connected to the chamfer, and the adhesive reservoir is formed by the large-diameter inner peripheral surface and the outer peripheral surface of the shaft member. 1. The hydrodynamic bearing device according to 1.   The hydrodynamic bearing device according to claim 2, wherein the large-diameter inner peripheral surface is a cylindrical surface.   The hydrodynamic bearing device according to claim 1, wherein a seal space is formed on an outer peripheral surface of the thrust member. A motor comprising the hydrodynamic bearing device according to claim 1, a stator coil, and a rotor magnet.

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