JP2009103252A - Fluid bearing device and motor having the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To inexpensively improve joining strength between a housing and a bearing sleeve. <P>SOLUTION: This fluid bearing device 1 has the bearing sleeve 8 and the housing 7 with the bearing sleeve 8 arranged on the inner periphery. The housing 7 is injectably molded by a melting resin by inserting the bearing sleeve 8, and also has integrally engaging parts 7e and 7f engaging in the axial direction with an outer peripheral corner part of the bearing sleeve 8. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a hydrodynamic bearing device and a motor including the same.

  The hydrodynamic bearing device is a bearing device that rotatably supports a rotation-side member with respect to a fixed-side member with a fluid lubricating film that fills the bearing gap. This hydrodynamic bearing device has characteristics such as high-speed rotation, high rotation accuracy, and low noise. In recent years, the hydrodynamic bearing device has been utilized as a motor bearing device for motors mounted on various electrical devices including information devices. More specifically, it is suitable as a bearing device incorporated in a spindle motor mounted on a disk drive device such as an HDD, a polygon scanner motor mounted on a laser beam printer (LBP), a fan motor mounted on a PC, or the like. in use.

  Among the above motors, for example, a hydrodynamic bearing device incorporated in a spindle motor for a disk drive device includes a radial bearing portion that supports a rotating member (for example, a shaft member) in a radial direction, and a thrust bearing portion that supports in a thrust direction. Have In recent years, both the radial bearing portion and the thrust bearing portion are opposed to each other through bearing gaps (radial bearing gap and thrust bearing gap) in order to meet the demand for higher rotational accuracy of the hydrodynamic bearing device. In many cases, at least one of the two surfaces is configured with a dynamic pressure bearing having a dynamic pressure generating portion such as a dynamic pressure groove.

This type of fluid dynamic bearing device generally includes a bearing sleeve that forms a radial bearing gap on the inner peripheral surface thereof, and a housing in which the bearing sleeve is disposed on the inner peripheral surface. Conventionally, the housing is often a metal machined product, but attempts have been made to replace the housing with a resin injection molded product in order to reduce the cost of the hydrodynamic bearing device (for example, Patent Document 1). See).
JP 2006-46461 A

  Recently, high performance (high capacity) and low prices of information equipment are rapidly progressing, so each component part of the hydrodynamic bearing device including the housing is made more accurate and low cost. However, there is a limit to reducing the cost only by changing the material of each component. Therefore, in order to further reduce the cost, the efficiency of the assembly process is an important point. As a means for improving the efficiency of the assembly process, it is conceivable to injection-mold the housing with resin using the bearing sleeve as an insert part. However, it is difficult to ensure a high bond strength between the two by simply molding the housing with resin using the bearing sleeve as an insert part. In recent years, mobile information devices have rapidly spread. However, since this type of information device is required to have higher impact resistance than before, it is desired to further increase the coupling strength between the housing and the bearing sleeve. Yes.

  Accordingly, an object of the present invention is to provide a hydrodynamic bearing device in which the coupling strength between the housing and the bearing sleeve is increased at a low cost.

  In order to achieve the above object, the present invention includes a housing and a bearing sleeve disposed on the inner periphery of the housing, and a fluid lubricating film formed in a radial bearing gap facing the inner peripheral surface of the bearing sleeve. In the hydrodynamic bearing device for supporting the shaft to be supported in the radial direction, the housing includes an engaging portion which is injection-molded with a molten material by inserting the bearing sleeve and engages with an outer peripheral corner portion of the bearing sleeve in the axial direction. Provided is a hydrodynamic bearing device characterized by having a single body.

  As described above, if the bearing sleeve is inserted and the housing is injection-molded with a molten material, the molding of the housing and the assembly of the bearing sleeve and the housing can be completed in one step. Further, since the housing integrally includes an engaging portion that engages with the outer peripheral corner portion of the bearing sleeve in the axial direction, the engaging sleeve that is formed at the same time as the housing is injection-molded is used. The relative movement in the axial direction can be restricted, and the coupling strength between the housing and the bearing sleeve, particularly the coupling strength (disengagement strength) in the axial direction can be increased. Note that examples of the molten material include a molten resin and a molten metal (for example, a low melting point metal such as magnesium or aluminum), and these may be selectively used according to required characteristics. For example, a molten resin is preferable for reducing the weight, and a molten metal is preferable for increasing the strength.

  As an example of a specific configuration, it is conceivable that a tapered surface (chamfering) is formed on the outer periphery of the bearing sleeve, and the engaging portion is brought into close contact with the tapered surface. Since the taper surface and the engaging portion are brought into close contact with each other in this manner, the relative movement of the housing and the bearing sleeve in the axial direction is restricted, so that a high pulling strength can be provided between the bearing sleeve and the housing. In addition, a large-diameter outer peripheral surface is formed on one end side of the tapered surface, a small-diameter outer peripheral surface having a smaller diameter than the large-diameter outer peripheral surface is formed on the other end side of the tapered surface, and the engaging portion is formed on the small-diameter outer peripheral surface and the tapered surface. It can be adhered. As a result, the outer peripheral corner portion of the bearing sleeve is formed into a stepped cylindrical surface, so that the engaging portion engages with the bearing sleeve in the axial direction in the region between the large diameter outer peripheral surface and the small diameter outer peripheral surface of the bearing sleeve. In the axial direction, the bearing sleeve and the housing are prevented from coming off. The former configuration is more advantageous than the latter configuration in terms of formability of the bearing sleeve. In the latter configuration, the engagement margin of the engaging portion (contact area between the engaging portion and the bearing sleeve) is less than the former configuration. This is advantageous in increasing the coupling strength between the housing and the bearing sleeve.

  When a large-diameter outer peripheral surface is provided on one end side of the tapered surface and a small-diameter outer peripheral surface is provided on the other end side of the tapered surface, the inclination direction of the tapered surface is arbitrary. That is, the taper surface may be of any form that gradually decreases in diameter toward the end of the bearing sleeve or that gradually increases in diameter. The former configuration has an advantage that the filling property of the molten material is better than that of the latter configuration, and the latter configuration is advantageous in terms of pull-out strength as compared with the former configuration.

  The engaging portion can be engaged with the outer peripheral corner portion of the bearing sleeve in the circumferential direction, and in this way, the relative movement of the bearing sleeve in the circumferential direction with respect to the housing can also be restricted. The bond strength between them is further increased. Such a configuration can be obtained, for example, by intermittently providing the tapered surface or the small-diameter outer peripheral surface to be provided in the bearing sleeve in the circumferential direction.

  The material for forming the bearing sleeve is not particularly limited, and it can be made of a soft metal material such as brass, or a porous material such as sintered metal or porous resin. A so-called anchor effect is exhibited by the penetration of the molten material into the surface pores of the bearing sleeve at the time of injection molding, and the coupling strength between the housing and the bearing sleeve is further improved.

  The above-described hydrodynamic bearing device can be suitably used by being incorporated in a motor having a stator coil and a rotor magnet, for example, a spindle motor for information equipment such as an HDD.

  As described above, according to the present invention, the coupling strength between the housing and the bearing sleeve can be increased at a low cost, and therefore, a hydrodynamic bearing device rich in impact resistance can be provided at a low cost.

  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. This spindle motor is used in a disk drive device such as an HDD, and is a stator coil that is opposed to a hydrodynamic bearing device 1 that rotatably supports a rotating member 3 having a shaft member 2 via a radial gap, for example. 4 and the rotor magnet 5, and a bracket 6 that fixes the hydrodynamic bearing device 1 to the inner periphery. The stator coil 4 is attached to the inner periphery of the outer diameter side cylindrical portion of the bracket 6, and the rotor magnet 5 is attached to the outer periphery of the disk hub 9 constituting the rotating member 3. The disk hub 9 holds one or more disks such as a magnetic disk (not shown). When the stator coil 4 is energized, the rotor magnet 5 is rotated by the electromagnetic force between the stator coil 4 and the rotor magnet 5, whereby the rotating member 3 and the disk held by the rotor member 5 are rotated together.

  FIG. 2 is an enlarged view of the hydrodynamic bearing device 1 shown in FIG. 1, and shows a first embodiment of the hydrodynamic bearing device according to the present invention. The hydrodynamic bearing device 1 shown in FIG. 1 includes a shaft member 2, a disk hub 9 provided at one end of the shaft member 2, a bearing sleeve 8 having the shaft member 2 inserted into the inner periphery, and an inner periphery of the bearing sleeve 8. And a lid member 10 that closes one end opening of the housing 7 as main components. For convenience of explanation, the following description will be given with the disk hub 9 side as the upper side and the lid member 10 side as the lower side.

  The shaft member 2 is formed of a metal material such as stainless steel, for example, in the shape of a shaft having substantially the same diameter over the entire length. A flange 11 as a retainer is screwed to the lower end of the shaft member 2, for example. Further, a screw hole for screwing a clamper (not shown) is provided on the inner periphery of the upper end portion of the shaft member 2.

  At the upper end of the shaft member 2, a disk hub 9 protruding outward in the radial direction (outer diameter side) is provided. In the present embodiment, the disc hub 9 is formed of a metal material such as stainless steel, and is engaged with a step provided at the upper end of the shaft member 2 by an appropriate means such as adhesion, press-fitting, or welding. Fixed. The disk hub 9 is integrally provided with a disk portion 9a that covers the upper end of the housing 7, a cylindrical portion 9b that extends downward from the outer diameter end of the disk portion 9a, and a flange portion 9d that protrudes outward from the cylindrical portion 9b. The flange portion 9d is provided with a disk mounting surface 9c. The rotor magnet 5 is fixed to the outer peripheral surface of the lower end of the cylindrical portion 9b by an appropriate means such as adhesion (see FIG. 1). The disk hub 9 can also be injection-molded with a molten material using the shaft member 2 as an insert part.

  The bearing sleeve 8 is made of a sintered metal porous body mainly composed of copper and is formed in a cylindrical shape. Of course, the material for forming the bearing sleeve 8 is not limited to this. For example, a porous body of sintered metal mainly composed of iron, a soft metal material such as brass, and other porous materials that are not sintered metal. It can also be formed of a material (porous resin or the like).

  On the inner peripheral surface 8a of the bearing sleeve 8, cylindrical regions serving as radial bearing surfaces of the first radial bearing portion R1 and the second radial bearing portion R2 are provided at two upper and lower positions separated in the axial direction. As shown in FIG. 3A, for example, a plurality of dynamic pressure grooves 8a1 and 8a2 arranged in a herringbone shape are formed as radial dynamic pressure generating portions. In the present embodiment, the upper dynamic pressure groove 8a1 is formed axially asymmetric with respect to the axial center m, and the axial dimension X1 of the upper region from the axial center m is the axial dimension X2 of the lower region. Is bigger than. On the other hand, the lower dynamic pressure groove 8a2 is formed symmetrically in the axial direction, and the axial dimensions of the upper and lower regions thereof are respectively equal to the axial dimension X2. Tapered surfaces (chamfers) 81 and 82 that are gradually reduced in diameter toward the outside in the axial direction of the bearing sleeve 8 are formed on the outer peripheral corners on the upper end side and the lower end side of the bearing sleeve 8 respectively. . The dynamic pressure groove may be formed on the outer peripheral surface 2a of the shaft member 2, and the shape thereof may be other known shapes such as a spiral shape.

  An annular region serving as a thrust bearing surface of the second thrust bearing portion T2 is provided on the lower end surface 8b of the bearing sleeve 8, and a thrust dynamic pressure generating portion is provided in the annular region, for example, as shown in FIG. As described above, a plurality of dynamic pressure grooves 8b1 arranged in a spiral shape are formed. The dynamic pressure groove 8b1 can also be formed on the upper end surface 11a of the flange 11, which will be described later, and the shape thereof may be other known shapes such as a herringbone shape.

  The housing 7 has a cylindrical shape with both ends opened. The inner peripheral surface of the housing 7 is divided into a small diameter inner peripheral surface 9a and a large diameter inner peripheral surface 9b in the axial direction. The lid member 10 is fixed to the large-diameter inner peripheral surface 9b by appropriate means such as press-fitting, adhesion, and welding, and the lower end opening of the housing 7 is thereby sealed.

  The upper end surface 7c of the housing 7 is provided with an annular region serving as a thrust bearing surface of the first thrust bearing portion T1, and although not shown, the annular region is arranged in a spiral shape as a thrust dynamic pressure generating portion. A plurality of dynamic pressure grooves are formed. The dynamic pressure groove can also be formed in the disk portion lower end surface 9a1 of the opposing disk hub 9, and the shape thereof can be other known shapes such as a herringbone shape.

  A tapered surface 7d that gradually increases in diameter upward is formed on the upper side of the outer peripheral surface of the housing 7, and this tapered surface 7d is formed between the inner peripheral surface 9b1 of the cylindrical portion 9b of the disk hub 9. An annular seal space S in which the radial dimension gradually decreases upward is formed. The seal space S communicates with the outer diameter side of the thrust bearing gap of the first thrust bearing portion T1 when the shaft member 2 (rotating member 3) rotates.

  A portion of the large-diameter inner peripheral surface 7a of the housing 7 that protrudes radially inward from the outer peripheral corners on the upper end side and the lower end side of the bearing sleeve 8 protrudes toward the inner diameter side, and the outer peripheral corner portion of the bearing sleeve 8 and the axial direction Engagement portions 7e and 7f that are engaged with each other are provided. The upper engaging portion 7e is in close contact with the tapered surface 81 of the bearing sleeve 8 over the entire circumference, and the lower engaging portion 7f is in close contact with the tapered surface 82 of the bearing sleeve 8 over the entire periphery. . Therefore, the engaging portions 7e and 7f each have a ring shape. The upper end surface of the upper engaging portion 7e is flush with the upper end surface 8d of the bearing sleeve 8, and the lower end surface of the lower engaging portion 7f is flush with the lower end surface 8b of the bearing sleeve 8. Is provided.

  Although not shown in the drawings, the housing 7 including the engaging portions 7e and 7f is inserted into the bearing sleeve 8 and injection molded with a molten resin. Of the injection mold used to mold the housing 7, a groove mold corresponding to the shape of the thrust dynamic pressure generating portion (dynamic pressure groove) is provided at a portion facing the upper end surface 7c of the housing 7, and the dynamic pressure groove Is molded simultaneously with the injection molding of the housing 7. There is no particular limitation on the shape and arrangement of the gate for injecting the molten resin into the cavity of the injection mold, but it is desirable to prevent the bearing sleeve 8 from being deformed by the injection pressure of the molten resin. In the injection mold, the point gates are equally arranged at three locations in the circumferential direction of the portion facing the outer peripheral edge portion (the portion where the upper end surface 7c and the tapered surface 7d intersect) on the upper end side of the housing 7.

  The molten resin used for the injection molding of the housing 7 is a resin composition using a thermoplastic resin as a base resin. There is no particular limitation on the thermoplastic resin that can be used as the base resin. For example, liquid crystal polymer (LCP), polyphenylene sulfide (PPS), polyether ether ketone (PEEK), polyacetal (POM), polyamide (PA) and the like are representative. Crystalline resins such as polyphenylsulfone (PPSU), polyethersulfone (PES), polyetherimide (PEI), and polyamideimide (PAI) can be used. Are used alone or in admixture of two or more. In this embodiment, polyphenylsulfone (PPSU) is used as the base resin.

  For the above base resin, if necessary, fibrous filler such as glass fiber, whisker-like filler such as potassium titanate, scaly filler such as mica, carbon fiber, carbon black, graphite, carbon nanomaterial One or more kinds of fillers in the form of fibers or powders such as metal powder can be filled (added).

  The internal space of the hydrodynamic bearing device 1 having the above configuration is filled with lubricating oil including the internal pores of the bearing sleeve 8. The above-described seal space S has a buffer function for absorbing a volume change amount associated with a temperature change of the lubricating oil filled in the internal space of the housing 7, and the lubricating oil is within the range of the assumed temperature change. The face is always in the seal space S.

  In the hydrodynamic bearing device 1 having the above-described configuration, when the rotating member 3 rotates, a region that becomes a radial bearing surface provided on the inner peripheral surface 8a of the bearing sleeve 8 in the axial direction is an outer peripheral surface 2a of the shaft member 2. And the radial bearing gap. As the rotary member 3 rotates, the oil film formed in the radial bearing gap has its oil film rigidity increased by the dynamic pressure action of the dynamic pressure grooves 8a1 and 8a2 formed on the radial bearing surface, and is rotated by this pressure. The member 3 is supported in a non-contact manner so as to be rotatable in the radial direction. As a result, the radial bearing portions R1 and R2 that support the rotary member 3 in a non-contact manner so as to be rotatable in the radial direction are spaced apart at two locations in the axial direction.

  When the rotating member 3 rotates, the thrust bearing surface region formed on the upper end surface 7c of the housing 7 faces the lower end surface 9a1 of the disk hub 9 via a predetermined thrust bearing gap, and at the same time. A region serving as a thrust bearing surface formed on the lower end surface 8b of the bearing sleeve 8 is opposed to the upper end surface 11a of the flange 11 with a predetermined thrust bearing gap therebetween. As the rotating member 3 rotates, the oil film formed in the thrust bearing gaps has its oil film rigidity increased by the dynamic pressure action of the dynamic pressure grooves formed on the thrust bearing surface. It is supported in a non-contact manner so as to be rotatable in both thrust directions. Thereby, the 1st thrust bearing part T1 and the 2nd thrust bearing part T2 which support the rotation member 3 so that rotation in both thrust directions is possible without contact are formed.

  Further, the leakage of the lubricating oil to the outside is effectively prevented by the capillary force of the seal space S and the lubricating oil drawing force (pumping force) by the dynamic pressure groove of the first thrust bearing portion T1.

  As described above, in the present invention, since the bearing sleeve 8 is inserted and the housing 7 is injection-molded with resin, the molding of the housing 7 and the assembly of the bearing sleeve 8 and the housing 7 can be completed in one step. . Further, the housing 7 is integrally provided with engaging portions 7e and 7f that are engaged with the outer peripheral corners of the bearing sleeve 8 in the axial direction. Since the housing 7 is injection-molded, the housing 7 is injected. The axial movement of the bearing sleeve 8 relative to the housing 7 can be restricted by the engaging portions 7e and 7f formed at the same time as the molding, and the coupling strength between the housing 7 and the bearing sleeve 8, particularly in the axial direction. Bond strength (stripping strength) can be increased.

  Further, since the bearing sleeve 8 is formed of a sintered metal porous body, at the time of injection molding of the housing 7, a so-called anchor effect is expressed by the penetration of the molten resin into the surface pores of the bearing sleeve 8, and the housing 7 and the bearing sleeve The bond strength between 8 can be further increased.

  Incidentally, the coupling strength (disengagement strength) between the housing 7 and the bearing sleeve 8 can be evaluated by, for example, the axial pressing force at which the bearing sleeve 8 falls off the inner peripheral surface 7a of the housing 7, and the configuration of the present invention. In the conventional product that does not employ the bearing sleeve 8, the bearing sleeve 8 falls off when the axial pressing force applied to one end surface of the bearing sleeve 8 reaches about 60N, whereas in the present product, the axial pressing force is 200N. The bearing sleeve 8 fell out only when the value exceeded.

  Although the embodiment has been described above in which the engaging portions 7e and 7f of the housing 7 are in close contact with the tapered surfaces 81 and 82 formed at the upper and lower peripheral corners of the bearing sleeve 8, respectively, the engaging portions 7e and 7f are described. The form of is not limited to the above. For example, the upper engaging portion 7e of the housing 7 has a large-diameter outer peripheral surface 83 on the lower end side of a tapered surface 81 formed on the outer periphery of the upper end of the bearing sleeve 8 as shown in FIG. 4 (a) or 5 (a). (Here, it is synonymous with the outer peripheral surface 8c shown in FIG. 2), and a small-diameter outer peripheral surface 84 can be formed on the upper end side of the tapered surface 81 and can be brought into close contact with the tapered surface 81 and the small-diameter outer peripheral surface 84. Further, as shown in FIG. 4B or 5B, the lower engaging portion 7f of the housing 7 has a large-diameter outer peripheral surface on the upper end side of the tapered surface 82 formed on the outer periphery of the lower end of the bearing sleeve 8. 83 (here, synonymous with the outer peripheral surface 8 c shown in FIG. 2), and a small-diameter outer peripheral surface 84 can be formed on the lower end side of the tapered surface 82, and can be brought into close contact with the tapered surface 82 and the small-diameter outer peripheral surface 84.

  The difference between the configuration shown in FIG. 4 and the configuration shown in FIG. 5 is that the inclined directions of the tapered surfaces 81 and 82 are different. Specifically, in the embodiment shown in FIGS. 4A and 4B, the large-diameter outer peripheral surface 83 and the small-diameter outer peripheral surface 84 are formed so as not to overlap each other, and a bearing sleeve is provided between the outer peripheral surfaces 83 and 84. 5A and 5B, the taper surfaces 81 and 82 are interposed such that the radial separation distance from the axis (center axis) increases toward the inner side in the axial direction of FIG. Both outer peripheral surfaces 83 and 84 are formed so that a part of the large-diameter outer peripheral surface 83 and a part of the small-diameter outer peripheral surface 84 overlap, and the axially inner side of the bearing sleeve 8 is formed between both the outer peripheral surfaces 83 and 84. Tapered surfaces 81 and 82 are interposed so that the radial distance from the central axis becomes smaller.

  In this way, as is clear from the illustrated example, the strength of the engaging portions 7e and 7f themselves is improved by the fact that the cross-sectional shapes of the engaging portions 7e and 7f are trapezoidal. Further, the engagement margin (the contact area between the engagement portion and the bearing sleeve 8) of the engagement portions 7e and 7f with respect to the bearing sleeve 8 is larger than that shown in FIG. Therefore, the coupling strength between the housing 7 and the bearing sleeve 8 can be further increased, and the relative movement in the axial direction of the bearing sleeve 8 with respect to the housing 7 can be more effectively regulated.

  The form shown in FIG. 4 is better in filling with molten resin when the housing 7 is insert-molded than the form shown in FIG. 5, and it is easy to form highly accurate engaging portions 7e and 7f. There is an advantage of being. On the other hand, the form shown in FIG. 5 is more advantageous in terms of missing strength than the form shown in FIG.

  Although illustration is omitted, it is possible to employ various combinations of the engaging portions 7e and 7f described above. For example, the engaging portion 7e that engages with the outer peripheral corner of the upper end of the bearing sleeve 8 is configured as shown in FIG. 4A, while the engaging portion 7f that engages with the outer peripheral corner of the lower end of the bearing sleeve 8 is shown in FIG. It can be set as the form shown in (b).

  Further, the hydrodynamic bearing device 1 to which the present invention is applicable is not limited to the above embodiment. Hereinafter, other embodiments of the hydrodynamic bearing device 1 to which the present invention can be applied will be described. However, the same reference numerals are assigned to the members and portions according to the above-described configuration, and the duplicate description will be omitted.

  FIG. 6 shows a second embodiment of the hydrodynamic bearing device according to the present invention. The main difference of the hydrodynamic bearing device 1 shown in FIG. 2 from that shown in FIG. 2 is that the shaft member 2 is protruded in the radial direction at two upper and lower positions so as to be positioned at both ends of the bearing sleeve 8. The seal members 19 and 20 are provided. The first thrust bearing portion T1 is provided between the lower end surface 19b of the seal member 19 and the upper end surface 8d of the bearing sleeve 8, and the second thrust bearing portion T2 is provided with the upper end surface 20b of the seal member 20 and the bearing. It is provided between the lower end surface 8 b of the sleeve 8. Further, the seal spaces S1 and S2 are open at both ends of the housing 7, that is, between the outer peripheral surface 19a of the seal member 19 and the inner peripheral surface 7a of the housing 7, and between the outer peripheral surface 20a of the seal member 20 and the inner periphery of the housing 7. It is provided between each surface 7a.

  FIG. 7 shows a third embodiment of a hydrodynamic bearing device according to the present invention. The main difference of the hydrodynamic bearing device 1 shown in FIG. 2 from that shown in FIG. 2 is that a seal member 30 provided separately on the inner peripheral surface 7a of the housing 7 is fixed, and the inner peripheral surface 30a of the seal member 30 and the shaft A first thrust bearing portion between the outer peripheral surface 2a of the member 2 and the lower end surface 8b of the bearing sleeve 8 and the upper end surface 11a of the flange 11 provided at the lower end of the shaft member 2 is provided. The second thrust bearing portion T2 is provided between the lower end surface 11b of the flange 11 and the upper end surface 10a of the lid member 10 at the point where T1 is provided.

  Although illustration is omitted, it is needless to say that the configuration shown in FIGS. 4 and 5 can also be adopted in the embodiments shown in FIGS.

  In addition, like the hydrodynamic bearing device 1 shown in FIGS. 2 and 6, a seal space S is formed on the outer peripheral surface and the inner peripheral surface of the housing 7, and the bearing sleeve 8 like the hydrodynamic bearing device 1 shown in FIG. 7 is formed. In the hydrodynamic bearing device having a configuration in which the seal member 30 that also functions as a retaining member is not provided, the bearing sleeve 8 can be effectively prevented from relatively moving upward in the axial direction. It is. Of course, in the hydrodynamic bearing device shown in FIG. 7, the coupling strength between the housing 7 and the bearing sleeve 8 is further improved, which is suitable for further increasing the strength.

  In the above, the tapered surfaces 81, 82 and the like are provided on the outer peripheral corners of the both ends of the bearing sleeve 8 over the entire circumference, and the engaging portions 7e, 7f are provided over the entire circumference in a manner corresponding to this (ring shape). The engaging portions 7e and 7f can be provided intermittently (provided in an arc shape). Such a configuration can be obtained by inserting the bearing sleeve 8 having the tapered surfaces 81 and 82 and the small-diameter outer peripheral surface 84 provided intermittently on the outer periphery and injection-molding the housing 7. In this way, the housing 7 and the bearing sleeve 8 are engaged in both the axial direction and the circumferential direction, and the relative movement in the axial direction and the circumferential direction of the bearing sleeve 8 with respect to the housing 7 is restricted. The coupling strength between the bearing sleeve 8 and the bearing sleeve 8 is further increased.

  In the above description, the case where the housing 7 is provided with the engaging portions 7e and 7f so as to be engaged with the outer peripheral corner portions of the both ends of the bearing sleeve 8 has been described. Only one of them can be provided. Whether the engaging portion is provided only on one end side or both end sides of the bearing sleeve 8 may be determined in consideration of the directionality of the axial pressing force acting on the bearing sleeve 8, for example.

  Moreover, although the case where the housing 7 was injection-molded with a molten resin was demonstrated above, the housing 7 can also be injection-molded with a molten metal. Examples of the metal material (molten metal) that can be used in this case include low melting point metals such as magnesium alloys and aluminum alloys. The housing 7 can also be a so-called MIM molded product. Thus, if the housing 7 is a metal injection-molded product, the weight of the housing 7 including the engaging portions 7e and 7f is slightly increased as compared with the above-described embodiment in which this is a resin injection-molded product. The strength can be increased, and therefore, the coupling strength between the housing 7 and the bearing sleeve 8 can be further increased.

  Further, in the above, as the radial bearing portions R1 and R2 and the thrust bearing portions T1 and T2, a configuration in which a dynamic pressure action is generated in the lubricating oil that fills the bearing gap by a herringbone-shaped or spiral-shaped dynamic pressure groove is illustrated. However, so-called step bearings, multi-arc bearings, or non-circular bearings may be used as the radial bearing portions R1 and R2, and so-called step bearings and wave bearings may be employed as the thrust bearing portions T1 and T2. In addition to the configuration in which the two radial bearing portions are separated from each other in the axial direction as in the radial bearing portions R1 and R2, one radial bearing portion is provided over the upper and lower regions on the inner peripheral side of the bearing sleeve 8. It is good also as a structure which provided the structure provided and three or more radial bearing parts spaced apart in the axial direction. Further, as the radial bearing portions R1 and R2, a perfect circular bearing having no dynamic pressure generating portion may be adopted, and as the thrust bearing portion, a pivot bearing that contacts and supports one end of the shaft member 2 may be adopted. .

  In the above description, the hydrodynamic bearing device 1 with the shaft member 2 as the rotation side and the housing 7 or the like as the fixed side has been described, but conversely, the shaft member 2 as the fixed side and the housing 7 or the like as the rotation side. The configuration of the present invention can also be suitably applied to the hydrodynamic bearing device 1 described above.

  In the above, the lubricating oil is exemplified as the lubricating fluid that fills the inside of the hydrodynamic bearing device 1. However, in addition to the lubricating oil, a gas such as air or grease can also be used.

It is sectional drawing which shows notionally an example of the spindle motor for information devices. It is sectional drawing which shows 1st Embodiment of the hydrodynamic bearing apparatus which concerns on this invention. (A) is a sectional view of the bearing sleeve, and (b) is a diagram showing a lower end surface of the bearing sleeve. (A) The figure is sectional drawing which shows the other structural example of the X section in FIG. 2, (b) The figure is sectional drawing which shows the other structural example of the Y section in FIG. (A) The figure is sectional drawing which shows the other structural example of the X section in FIG. 2, (b) The figure is sectional drawing which shows the other structural example of the Y section in FIG. It is sectional drawing which shows 2nd Embodiment of the hydrodynamic bearing apparatus which concerns on this invention. It is sectional drawing which shows 3rd Embodiment of the hydrodynamic bearing apparatus which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fluid dynamic bearing apparatus 2 Shaft member 3 Rotating member 7 Housing 7e, 7f Engagement part 8 Bearing sleeve 81, 82 Tapered surface 83 Large diameter outer peripheral surface 84 Small diameter outer peripheral surface R1, R2 Radial bearing part T1, T2 Thrust bearing part S Seal space

Claims (6)

A fluid that includes a housing and a bearing sleeve disposed on the inner periphery of the housing, and that supports a shaft to be supported in a radial direction by a fluid lubricating film formed in a radial bearing gap that faces the inner peripheral surface of the bearing sleeve In the bearing device,
A hydrodynamic bearing device, wherein the housing is integrally formed with an insertion portion that is inserted into the bearing sleeve and injection-molded with a molten material, and that engages with an outer peripheral corner portion of the bearing sleeve in the axial direction.   The hydrodynamic bearing device according to claim 1, wherein the engaging portion is in close contact with a tapered surface formed on the outer periphery of the bearing sleeve.   A large-diameter outer peripheral surface is formed on one end side of the tapered surface, and a small-diameter outer peripheral surface having a smaller diameter than the large-diameter outer peripheral surface is formed on the other end side of the tapered surface, and the engaging portion is brought into close contact with the small-diameter outer peripheral surface and the tapered surface. The hydrodynamic bearing device according to claim 2.   The hydrodynamic bearing device according to claim 1, wherein the engaging portion is engaged with an outer peripheral corner portion of the bearing sleeve in a circumferential direction.   The hydrodynamic bearing device according to claim 1, wherein the bearing sleeve is formed of a porous material.   A motor comprising the hydrodynamic bearing device according to claim 1, a stator coil, and a rotor magnet.

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