JP2007071274A - Dynamic pressure bearing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a dynamic pressure bearing device at low cost having high shaft strength and capable of maintaining desired rotation precision. <P>SOLUTION: A first flange part 9 and a second flange part 10 are bonded and fixed at a predetermined position on an outer peripheral face 2a1 of a shaft part 2a. An adhesive clearance is provided among an inner peripheral face 9d of the first flange part 9, an inner peripheral face 10d of the second flange part 10, and the outer peripheral face 2a1 of the shaft part 2a in a bonding and fixing part 14 of the first flange part 9, the second flange part 10, and the shaft part 2a. Adhesive 13 is filled into the adhesive clearance and a spiral channel 12 and is solidified. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a hydrodynamic bearing device.

  The hydrodynamic bearing device is a bearing device that supports the shaft member in a non-contact manner by the dynamic pressure action of the lubricating fluid generated in the bearing gap due to the relative rotation between the shaft member and the bearing member. This hydrodynamic bearing device has characteristics such as high-speed rotation, high rotation accuracy, and low noise. In recent years, utilizing these characteristics, information devices such as magnetic disk devices such as HDD and FDD, CD-ROM, For spindle motors mounted on optical disk devices such as CD-R / RW and DVD-ROM / RAM, magneto-optical disk devices such as MD, MO, etc., for polygon scanner motors mounted on laser beam printers (LBP), etc., personal computers It is widely used as a bearing for a fan motor mounted on a (PC) or the like, or a small motor mounted on an electric device such as an axial fan.

  The above-mentioned hydrodynamic bearing device is a non-contact type in which the radial bearing portion is constituted by a hydrodynamic bearing, the thrust bearing portion is constituted by a pivot bearing, and both the radial bearing portion and the thrust bearing portion are constituted by dynamic pressure bearings. They are broadly classified into contact types and are properly used according to the intended use.

  Among these, the form shown in FIG. 6 can be given as an example of a non-contact type hydrodynamic bearing device. The shaft member 20 used in the dynamic pressure bearing device of this embodiment includes a shaft portion 20a and a flange portion 20b projecting to the outer diameter side of the shaft portion 20a. The radial bearing portion R is formed in a radial bearing gap between the outer peripheral surface of the shaft portion 20 a and the inner peripheral surface of the sleeve portion 80 constituting the bearing member 70. The thrust bearing portion T is formed in a thrust bearing gap between the upper end surface of the flange portion 20b and the lower end surface of the sleeve portion 80 and between the lower end surface of the flange portion 20b and the upper end surface of the thrust member 71. The

  In recent years, the above-described information equipment has been rapidly improved in performance, and accordingly, higher rotational accuracy is required for the hydrodynamic bearing device. In order to increase the rotational accuracy of the hydrodynamic bearing device, it is important to manage the clearance of the radial bearing gap and the thrust bearing gap. Of these, the optimization of the clearance management of the thrust bearing gap is particularly important between the shaft portion 20a and the flange portion 20b. Influenced by bond strength. Further, since the flange portion 20b also has a function of preventing the shaft member 20 from coming off, the coupling strength between the shaft portion 20a and the flange portion 20b is also important in this respect. As described above, since a high bonding strength is required between the shaft portion and the flange portion, the shaft member is cut as proposed in, for example, Japanese Patent Laid-Open No. 2003-307221 (Patent Document 1). In many cases, it is integrally formed by machining such as.

Japanese Patent Laid-Open No. 2000-291649 (Patent Document 2) describes that the shaft portion and the flange portion are formed separately and the flange portion is press-fitted and fixed to the shaft portion.
JP 2003-307221 A JP 2000-291649 A

  On the other hand, the price of information equipment is rapidly decreasing along with the improvement in performance, and the cost reduction for the hydrodynamic bearing device is also becoming more severe. However, when the shaft member is integrally formed as in Patent Document 1, since advanced processing equipment and processing technology are required, the processing cost increases and it is difficult to meet the demand for cost reduction. There is.

  In addition, the shaft part and the flange part are formed separately, and the flange part is press-fitted and fixed to the shaft part. As a result, the part processing cost increases.

  Accordingly, the present invention provides a hydrodynamic bearing in which the shaft portion and the flange portion are separated from each other, and a high coupling strength between them can be obtained relatively easily, thereby maintaining the desired bearing performance. The object is to provide a device at low cost.

  In order to solve the above problems, a hydrodynamic bearing device according to the present invention includes a bearing member having a sleeve portion, the shaft portion inserted into the inner periphery of the sleeve portion, and an outer diameter side of the shaft portion. The shaft member is not contacted in the radial direction by the dynamic pressure action of the lubricating fluid generated in the radial bearing gap between the shaft member having the provided flange portion and the inner peripheral surface of the sleeve portion and the outer peripheral surface of the shaft portion. A radial bearing portion to be supported, and a thrust bearing portion for supporting the shaft member in a thrust direction in a thrust direction by a dynamic pressure action of a lubricating fluid generated in a thrust bearing gap between an end surface of the sleeve portion and an end surface of the flange portion. The flange portion is adhesively fixed to the outer peripheral surface of the shaft portion, and an adhesive filling portion is formed in the adhesive fixing portion.

  According to the configuration of the present invention, since the shaft portion and the flange portion are joined and integrated by adhesive fixing, the manufacturing cost of the shaft member can be reduced as compared with a case where both are integrally formed. In addition, since the adhesive filling part is provided in the adhesive fixing part between the shaft part and the flange part, in addition to the increase in the adhesion area, the anchor effect of the adhesive filled in the adhesive filling part increases the bond strength between the two. Can be increased. Further, if the assembly accuracy (for example, squareness) between the shaft portion and the flange portion is increased, the thrust bearing gap width can always be managed and maintained with high accuracy.

  The adhesive filling portion can be formed by a spiral groove provided on at least one of the outer peripheral surface of the shaft portion and the inner peripheral surface of the flange portion. If the adhesive filling portion is formed of a spiral groove in this manner, the bonding area can be increased and the bond strength can be greatly improved by the anchor effect rather than simply providing a circumferential groove. In addition, a stable effect can be exhibited even when the adhesive force decreases due to a temperature change in the use environment and an axial shearing force acts on the flange portion.

  In addition, in the region excluding the adhesive filling portion, the adhesive fixing portion includes a case where the inner peripheral surface of the flange portion is bonded to the outer peripheral surface of the shaft portion via an adhesive layer (so-called loose bonding), and The inner peripheral surface may be press-fitted into the outer peripheral surface of the shaft portion. In the former case, so-called loose bonding is performed, and in the latter case, the shaft portion and the flange portion are fixed to each other by a combination of bonding and press-fitting.

  The above configuration of the present invention is also applied to a hydrodynamic bearing device having a configuration in which, for example, the flange portion is disposed at both ends of the sleeve portion, that is, a hydrodynamic bearing device in which the thrust bearing portion is provided on both axial sides of the sleeve portion. It can be preferably applied.

  The configuration of the present invention can also be preferably applied to a dynamic pressure bearing device having a configuration in which a seal space opened to the atmosphere is provided on the outer periphery of the flange portion. In this case, the flange portion functions not only for forming the thrust bearing portion but also as a member for forming the seal space. Even in such a configuration, since the coupling strength between the shaft portion and the flange portion is ensured, the width of the seal space (radial width) is always controlled to an appropriate value, so that the lubricating fluid can be surely leaked out. Can be prevented. At this time, since the number of parts can be reduced as compared with the fluid dynamic bearing device having the configuration shown in FIG. 6, the cost of the fluid dynamic bearing device can be reduced.

  The hydrodynamic bearing device having the above configuration can be preferably used for a motor having a rotor magnet and a stator coil, for example, a spindle motor for HDD.

  As described above, according to the present invention, it is possible to provide a hydrodynamic bearing device that can fix the shaft portion and the flange portion with relatively high coupling strength, thereby maintaining the desired bearing performance at low cost. I can do it.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  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 the present invention. This spindle motor is used in a disk drive device such as an HDD, and includes a hydrodynamic bearing device 1 that rotatably supports the shaft member 2 in a non-contact manner, a rotor (disk hub) 3 mounted on the shaft member 2, For example, a stator coil 4a and a rotor magnet 4b that are opposed to each other via a gap in the radial direction 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 housing 7 of the hydrodynamic bearing device 1 is mounted on the inner periphery of the bracket 5. The disk hub 3 holds one or more disks D such as magnetic disks. When the stator coil 4a is energized, the rotor magnet 4b is rotated by the electromagnetic force between the stator coil 4a and the rotor magnet 4b, whereby the disk hub 3 and the shaft member 2 are rotated together.

  FIG. 2 shows an example of the hydrodynamic bearing device 1 used in the spindle motor. The hydrodynamic bearing device 1 includes a rotation-side shaft member 2 and a fixed-side bearing member 6 as main components. In the present embodiment, the shaft member 2 includes a shaft portion 2a, a first flange portion 9 and a second flange portion 10 fixed to the shaft portion 2a, and the bearing member 6 includes a housing 7, The sleeve portion 8 is configured separately. For convenience of explanation, the description will be given with the side where the end of the shaft member 2 (shaft 2a) projects from the opening of the bearing member 6 as the upper side and the opposite side in the axial direction as the lower side.

  In the present embodiment, the first radial bearing portion R1 and the second radial bearing portion R2 are separated in the axial direction between the inner peripheral surface 8a of the sleeve portion 8 and the outer peripheral surface 2a1 of the shaft portion 2a constituting the shaft member 2. Provided. A first thrust bearing portion T1 is provided between the upper end surface 8b of the sleeve portion 8 and the lower end surface 9b of the first flange portion 9, and the lower end surface 8c of the sleeve portion 8 and the upper side of the second flange portion 10 are provided. A second thrust bearing portion T2 is provided between the end surface 10b. In the hydrodynamic bearing device 1 of the present embodiment, the thrust bearing portions are formed at both ends of the sleeve portion 8, so that the axial separation distance between the thrust bearing portions is larger than that of the hydrodynamic bearing device of the configuration shown in FIG. 6. The load capacity with respect to the moment load in the thrust bearing portion can be increased accordingly.

  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 material forming the housing 7 can be used regardless of whether it is an injection-moldable resin material, such as an amorphous resin or a crystalline resin. For example, as the amorphous resin, polysulfone (PSF), polyethersulfone ( Liquid crystalline polymer (LCP), polyetheretherketone (PEEK), polybutylene terephthalate (PBT), polyphenylene sulfide (PPS) as crystalline resins such as PES), polyphenylsulfone (PPSU), polyetherimide (PEI) Etc. can be used. Of course, these are only examples, and other resin materials suitable for the application and use environment of the bearing can also be used. One or more kinds of various fillers such as a reinforcing material (fibrous, powdery form, etc.), a lubricant, and a conductive material are blended in the resin material as necessary.

  In addition, the housing 7 can also be formed of a soft metal material such as brass or an aluminum alloy, or other metal materials.

  The sleeve portion 8 is formed, for example, in a cylindrical shape with a porous body made of sintered metal, particularly a sintered body of sintered metal mainly composed of copper, and is press-fitted and bonded to a predetermined position on the inner peripheral surface 7 a of the housing 7. Alternatively, it is fixed by means such as press-fit adhesion. Note that the sleeve portion 8 can be formed of not only a sintered metal but also a metal material other than a porous body, for example, a soft metal such as brass.

  The inner peripheral surface 8a of the sleeve portion 8 is provided with two upper and lower regions that are radial bearing surfaces of the first radial bearing portion R1 and the second radial bearing portion R2, and are separated in the axial direction. For example, herringbone-shaped dynamic pressure grooves 8a1 and 8a2 as shown in FIG. 3B are formed. As the dynamic pressure groove shape, other known shapes such as a spiral shape can also be formed.

  Further, a thrust bearing surface of the first thrust bearing portion T1 is formed in a part or all of the annular region of the upper end surface 8b of the sleeve portion 8, and the region serving as the thrust bearing surface is, for example, as shown in FIG. A spiral dynamic pressure groove 8b1 as shown is formed. Similarly, a thrust bearing surface of the second thrust bearing portion T2 is formed in a part or all of the annular region of the lower end surface 8c of the sleeve portion 8, and the region serving as the thrust bearing surface includes, for example, FIG. The spiral dynamic pressure groove 8c1 as shown in FIG. The dynamic pressure groove shape can be formed in, for example, a herringbone shape in addition to the spiral shape.

  The shaft member 2 includes a metal material such as stainless steel, or a shaft portion 2a having a hybrid structure of metal and resin, and a first flange portion 9 and a second flange portion 10 projecting to the outer diameter side of the shaft portion 2a. It consists of. The shaft portion 2a as a whole has a shaft shape with substantially the same diameter, and a relief portion 2a2 having a slightly smaller diameter than the other portions is formed in the middle portion thereof.

  The first flange portion 9 and the second flange portion 10 are both formed of a soft metal material such as brass, other metal materials, or a resin material in a ring shape that is separate from the shaft portion 2a. Glued in place. In this embodiment, a part or all of the inner peripheral surface 9d of the first flange portion 9 and the inner peripheral surface 10d of the second flange portion 10 are shown in the enlarged view of FIG. 2 (the enlarged view on the right side in the drawing). As shown, a spiral groove 12 as an adhesive filling portion is formed. The inclination angle and groove width of the spiral groove 12 are formed to have an arbitrary inclination angle and groove width so that a high bonding force can be exerted at the time of adhesion and fixation. In addition, as an adhesive agent filling part, it can also be set as the structure which provided other groove shape, for example, one or some circumferential groove.

  In the adhesive fixing portion 14 between the first flange portion 9 and the second flange portion 10 and the shaft portion 2a, the inner peripheral surface 9d of the first flange portion 9 and the inner peripheral surface 10d of the second flange portion 10 and the outer periphery of the shaft portion 2a An adhesive gap is provided between the surface 2a1 and the adhesive 13 is filled in the adhesive gap and the spiral groove 12 to be solidified.

  A first seal space S1 having a predetermined volume is formed between the outer peripheral surface 9a of the first flange portion 9 and the inner peripheral surface 7a of the upper end opening of the housing 7, and the outer peripheral surface 10a of the second flange portion 10 is A second seal space S <b> 2 having a predetermined volume is formed between the inner peripheral surface 7 a of the lower end opening of the housing 7. In this embodiment, the outer peripheral surface 9a of the 1st flange part 9 and the outer peripheral surface 10a of the 2nd flange part 10 are each formed in the taper surface shape gradually diameter-reduced toward the outer side of the bearing apparatus. Therefore, both the seal spaces S1 and S2 have a tapered shape that is gradually reduced in diameter in a direction approaching each other (inner direction of the housing 7). When the shaft member 2 is rotated, the lubricating oil in both the seal spaces S1 and S2 is drawn in a direction (inside the housing 7) 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. It is drawn toward. Thereby, the leakage of the lubricating oil from the inside of the housing 7 is effectively prevented. In order to reliably prevent oil leakage, as shown in the enlarged view of FIG. 2 (the enlarged view on the left side in the figure), the upper end face 7b and the lower end face 7c of the housing 7, the upper end face 9c of the first flange portion 9, The coating 11 made of an oil repellent agent can also be formed on the lower end surface 10c of the second flange portion 10, respectively.

  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.

  The hydrodynamic bearing device 1 composed of the above constituent members is assembled as follows, for example.

  After the shaft portion 2a is inserted into the inner periphery of the sleeve portion 8, the first flange portion 9 and the second flange portion 10 are bonded and fixed to predetermined portions of the shaft portion 2a so as to sandwich the sleeve portion 8. For example, in a state in which a thermosetting adhesive is applied as the adhesive 13 to the inner peripheral surfaces of the both flange portions 9 and 10, the both flange portions 9 and 10 are extrapolated to the shaft portion 2a, and each of the shaft portions 2a reaches a predetermined position. Move to perform positioning. Thereafter, when heat treatment (baking) is performed, the adhesive 13 filled in the bonding gap and the spiral groove 12 is solidified, and the flange portions 9 and 10 are bonded and fixed to the shaft portion 2a. The assembly formed in this way is inserted into the inner periphery of the housing 7, and the outer peripheral surface of the sleeve portion 8 is bonded, press-fitted, press-fitted, and welded (ultrasonic welding) to the inner peripheral surface 7 a of the housing 7. Etc. are fixed by appropriate means. When the assembly is completed in this manner, the internal space of the housing 7 sealed by the flange portions 9 and 10 is filled with, for example, lubricating oil as a lubricating fluid including the internal pores of the sleeve portion 8.

  In addition, lubrication of the lubricating oil in the illustrated dynamic pressure bearing device 1 is performed, for example, by immersing the unlubricated dynamic pressure bearing device in the lubricating oil in a vacuum chamber and then releasing it to atmospheric pressure. In the hydrodynamic bearing device 1 of the present embodiment, since both ends of the housing 7 are open, the air in the internal space is reliably replaced with lubricating oil as compared with a configuration in which one end of the housing 7 is closed (see FIG. 6). It is possible to reliably avoid adverse effects caused by residual air, such as oil leakage at high temperatures. In addition to such a lubrication method using reduced pressure, it is possible to lubricate under normal pressure (for example, pressurized lubrication of lubricating oil), simplifying the lubrication equipment and processes, and reducing manufacturing costs. Can do.

  In the dynamic pressure bearing device 1 having the above-described configuration, when the shaft member 2 rotates, the regions provided separately at the two upper and lower positions serving as the radial bearing surface of the inner peripheral surface 8a of the sleeve portion 8 are the outer peripheral surfaces of the shaft member 2, respectively. It faces 2a via a radial bearing gap. As the shaft member 2 rotates, the lubricating oil film formed in the radial bearing gap is increased in rigidity by the dynamic pressure action of the dynamic pressure groove, and the shaft member 2 is supported in a non-contact manner so as to be rotatable in the radial direction. Is done. As a result, 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 formed.

  Further, when the shaft member 2 rotates, the region that becomes the thrust bearing surface of the upper end surface 8b of the sleeve portion 8 faces the lower end surface 9b of the first flange portion 9 via a predetermined thrust bearing gap, and the sleeve portion 8 A region serving as a thrust bearing surface of the lower end surface 8c faces the upper end surface 10b of the second flange portion 10 via a predetermined thrust bearing gap. As the shaft member 2 rotates, the oil film rigidity of the lubricating oil film formed in the thrust bearing gap is increased by the dynamic pressure action of the dynamic pressure groove, and the shaft member 2 is supported in a non-contact manner so as to be rotatable in the thrust direction. The Thereby, the 1st thrust bearing part T1 and the 2nd thrust bearing part T2 which support the shaft member 2 in a non-contact manner so as to be rotatable in the thrust direction are formed.

  2 illustrates the form in which the spiral groove 12 as the adhesive filling portion is formed on the inner peripheral surfaces of the flange portions 9 and 10, the spiral groove 12 has a shaft portion as shown in FIG. In addition to being formed on the outer peripheral surface 2a1 of 2a, as shown in FIG. 4B, it may be formed on both the outer peripheral surface 2a1 of the shaft portion 2a and the inner peripheral surface of the flange portion. In the configuration described above, an adhesive gap is provided between the inner peripheral surface 9d of the first flange portion 9 and the inner peripheral surface 10d of the second flange portion 10 and the outer peripheral surface 2a1 of the shaft portion 2a. However, as shown in FIG. 4C, for example, an area excluding the spiral groove 12 on the inner peripheral surface 9d of the first flange portion 9 (inner peripheral surface 10d of the second flange portion 10) is used. You may make it press-fit in the outer peripheral surface 2a1 of the axial part 2a.

  FIG. 5 shows a second embodiment of the hydrodynamic bearing device 1. In the illustrated dynamic pressure bearing device 1, in FIG. 2, a bearing member 6 constituted by a separate housing 7 and a sleeve portion 8 is constituted by an integral housing 7 and a sleeve portion 8. Thus, by making the bearing member 6 into a single component, it is possible to further reduce the cost by reducing the number of components and the number of assembly steps. The bearing member 6 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 by MIM molding.

  In this case, in the bearing member 6, a radial bearing gap is formed between the inner peripheral surface of the sleeve portion 8 and the outer peripheral surface of the shaft member 2, and the upper end surface 8 b of the sleeve portion 8 and the lower side of the first flange portion 9. Thrust bearing gaps are formed between the end surface 9 b and between the lower end surface 8 c of the sleeve portion 8 and the upper end surface 10 b of the second seal portion 10. Further, seal spaces S1 and S2 are formed between the inner peripheral surface 7a of the both end openings of the bearing member 6 (both end openings of the portion 7 corresponding to the housing) and the outer peripheral surfaces of the flange portions 9 and 10, respectively.

  In the above description, the form in which the flange part is disposed at both ends of the sleeve part is illustrated, but of course, the hydrodynamic bearing device in the form in which the flange part is disposed only at one end of the sleeve part (for example, the form shown in FIG. 6). The configuration of the present invention can be preferably applied.

  In the above description, the radial bearing portions R1 and R2 and the thrust bearing portions T1 and T2 are exemplified by the configuration in which the dynamic pressure action of the lubricating oil is generated by the herringbone shape and spiral shape dynamic pressure grooves. The present invention is not limited to this.

  For example, so-called step bearings or multi-arc bearings may be employed as the radial bearing portions R1 and R2.

  FIG. 7 shows an example in which one or both of the radial bearing portions R1 and R2 are configured by step bearings. In this example, a plurality of axial groove-shaped dynamic pressure grooves 8a3 are provided at predetermined intervals in the circumferential direction in a region serving as a radial bearing surface of the inner peripheral surface 8a of the sleeve portion 8.

  FIG. 8 shows an example of a case where one or both of the radial bearing portions R1 and R2 are configured by multi-arc bearings. In this example, a region serving as a radial bearing surface of the inner peripheral surface 8a of the sleeve portion 8 is configured by three arc surfaces 8a4, 8a5, and 8a6 (so-called three arc bearings). The centers of curvature of the three arcuate surfaces 8a4, 8a5, and 8a6 are offset by the same distance from the axis center O of the sleeve portion 8 (shaft portion 2a). In each region defined by the three arcuate surfaces 8a4, 8a5, and 8a6, the radial bearing gap has a shape gradually reduced in a wedge shape in both circumferential directions. Therefore, when the sleeve portion 8 and the shaft portion 2a rotate relative to each other, the lubricating oil in the radial bearing gap is pushed into the minimum gap side reduced in a wedge shape according to the direction of the relative rotation, and the pressure rises. By such a dynamic pressure action of the lubricating oil, the sleeve portion 8 and the shaft portion 2a are supported in a non-contact manner. Note that a deeper axial groove called a separation groove may be formed at the boundary between the three arcuate surfaces 8a4, 8a5, 8a6.

  FIG. 9 shows another example in the case where one or both of the radial bearing portions R1 and R2 are configured by multi-arc bearings. Also in this example, the region that becomes the radial bearing surface of the inner peripheral surface 8a of the sleeve portion 8 is configured by three arc surfaces 8a7, 8a8, and 8a9 (so-called three arc bearings), but the three arc surfaces 8a7, In each region partitioned by 8a8 and 8a9, the radial bearing gap has a shape gradually reduced in a wedge shape with respect to one direction in the circumferential direction. The multi-arc bearing having such a configuration may be referred to as a taper bearing. Further, deeper axial grooves 8a10, 8a11, and 8a12 called separation grooves are formed at boundaries between the three arcuate surfaces 8a7, 8a8, and 8a9. Therefore, when the sleeve portion 8 and the shaft portion 2a are relatively rotated in a predetermined direction, the lubricating oil in the radial bearing gap is pushed into the minimum gap side reduced in a wedge shape, and the pressure rises. By such a dynamic pressure action of the lubricating oil, the sleeve portion 8 and the shaft portion 2a are supported in a non-contact manner.

  FIG. 10 shows another example in the case where one or both of the radial bearing portions R1 and R2 are configured by multi-arc bearings. In this example, in the configuration shown in FIG. 9, the predetermined areas θ on the minimum gap side of the three arcuate surfaces 8a7, 8a8, 8a9 are concentric with the center O of the sleeve 8 (the shaft 2a) as the center of curvature. It is composed of arcs. Therefore, in each predetermined area θ, the radial bearing gap (minimum gap) is constant. The multi-arc bearing having such a configuration may be referred to as a tapered flat bearing.

  The multi-arc bearings in the above examples are so-called three-arc bearings, but are not limited to this, and so-called four-arc bearings, five-arc bearings, and multi-arc bearings composed of more than six arc surfaces are adopted. You may do it. Further, when the radial bearing portion is configured by a step bearing or a multi-arc bearing, the radial bearing portions R1 and R2 are configured such that two radial bearing portions are provided apart from each other in the axial direction. It is good also as a structure which provided the one radial bearing part over the up-and-down area | region of the internal peripheral surface 8a.

  Further, one or both of the thrust bearing portions T1 and T2 are, for example, so-called step bearings, so-called wave bearings, in which a plurality of radial groove-shaped dynamic pressure grooves are provided at predetermined intervals in the circumferential direction in a region serving as a thrust bearing surface. It can also be constituted by a mold bearing (a step type having a wave shape) or the like (not shown).

  In the above embodiment, the inside of the hydrodynamic bearing device 1 is filled, and the radial bearing gap between the sleeve portion 8 and the shaft member 2 (shaft portion 2a) or the sleeve portion 8 and the shaft member 2 (both flange portions 9) are filled. 10), the lubricating oil is exemplified as the fluid that generates the dynamic pressure in the thrust bearing gap between them, but other fluids that can generate the dynamic pressure in each bearing gap, for example, gas such as air, A magnetic fluid or the like can also be used.

  Furthermore, in the above description, the case where the radial bearing surface is formed on the inner peripheral surface 8a of the sleeve portion 8 is exemplified. However, the radial bearing surface is formed on the surface facing the radial bearing gap, that is, the outer peripheral surface 2a1 of the shaft portion 2a. You can also. Furthermore, although the case where the thrust bearing surface is formed on both end surfaces 8b and 8c of the sleeve portion 8 is illustrated, the surfaces facing each other through the thrust bearing gap, that is, the lower end surface 9b and the second flange portion of the first flange portion 9. 10 may be formed on the upper end face 10b.

1 is a cross-sectional view of a spindle motor for information equipment incorporating a fluid dynamic bearing device according to an embodiment of the present invention. It is sectional drawing which shows the dynamic pressure bearing apparatus which concerns on embodiment of this invention. (A) A figure is a figure which shows the upper side cross section of a sleeve part, (b) A figure is sectional drawing of a sleeve part, (c) A figure is a figure which shows the lower end surface of a sleeve part. (A)-(c) figure is a figure which shows the other structure of the expanded sectional view shown in FIG. It is a figure which shows 2nd Embodiment of the hydrodynamic bearing apparatus which concerns on embodiment of this invention. It is sectional drawing which shows the hydrodynamic bearing apparatus of a conventional structure. It is sectional drawing which shows other embodiment of a radial bearing part. It is sectional drawing which shows other embodiment of a radial bearing part. It is sectional drawing which shows other embodiment of a radial bearing part. It is sectional drawing which shows other embodiment of a radial bearing part.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Dynamic pressure bearing apparatus 2 Shaft member 2a Shaft part 6 Bearing member 7 Housing 8 Sleeve part 9 1st flange part 10 2nd flange part 12 Spiral groove 13 Adhesive 14 Adhesive fixing part R1, R2 Radial bearing part T1, T2 Thrust bearing Part S1, S2 Seal space

Claims (5)

A bearing member provided with a sleeve portion, a shaft member inserted on the inner periphery of the sleeve portion, a shaft member provided with a flange portion protruding from the outer diameter side of the shaft portion, and an inner peripheral surface of the sleeve portion And a radial bearing portion that supports the shaft member in a non-contact manner in a radial direction by a dynamic pressure action of a lubricating fluid generated in a radial bearing gap between the shaft portion and an outer peripheral surface of the shaft portion, an end surface of the sleeve portion, and an end surface of the flange portion A dynamic bearing device comprising a thrust bearing portion that supports the shaft member in a thrust direction in a thrust direction by a dynamic pressure action of a lubricating fluid generated in a thrust bearing gap between
The hydrodynamic bearing device according to claim 1, wherein the flange portion is bonded and fixed to the outer peripheral surface of the shaft portion, and an adhesive filling portion is formed in the adhesive fixing portion.   2. The dynamic pressure according to claim 1, wherein the adhesive filling portion is formed by a spiral groove provided in at least one of an outer peripheral surface of the shaft portion and an inner peripheral surface of the flange portion. Bearing device.   The hydrodynamic bearing device according to claim 1, wherein the flange portion is disposed at both ends of the sleeve portion.   The hydrodynamic bearing device according to claim 1, wherein a seal space that is open to the atmosphere is formed on an outer periphery of the flange portion.   A motor comprising the fluid dynamic bearing device according to claim 1, a stator coil, and a rotor magnet.

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