JP2009024844A - Dynamic-pressure bearing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To avoid a deterioration in assembly precision between a shaft and a flange, in a dynamic-pressure bearing device in which a shaft member has the shaft and the flange, and one end of the shaft member is pivotally supported. <P>SOLUTION: The dynamic-pressure bearing device 1 comprises the shaft member 2 and a bearing sleeve 8 which is arranged at the external periphery of the shaft member 2, and relatively rotates with respect to the shaft member 2. The shaft member 2 has the shaft 21, the flange 22 and a sliding part 23. The flange 22 is engaged with the lower-side end face 8b of the bearing sleeve 8 as a regulation part in the axial direction, and regulates the fall-off of the shaft member 2. The sliding part 23 contacts the bottom of a housing 7 as a thrust receiving part, and supports a thrust load. The flange 22 and the sliding part 23 are formed to be integrated with each other. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a hydrodynamic bearing device.

  The hydrodynamic bearing device is a bearing device that rotatably supports a rotating member (for example, a shaft member) by a hydrodynamic action of fluid generated in a bearing gap. This hydrodynamic bearing device has characteristics such as high-speed rotation, high rotation accuracy, and low noise, and in recent years, taking advantage of the characteristics, the bearing device for motors mounted on various electric devices including information equipment. More specifically, it is mounted on a spindle motor or laser beam printer (LBP) mounted on a magnetic disk device such as an HDD or an optical disk device such as a CD-ROM, CD-R / RW, or DVD-ROM / RAM. It is preferably used as a bearing device for motors such as polygon scanner motors and fan motors mounted on PCs.

  This type of hydrodynamic bearing device has a radial bearing portion that supports the shaft member in the radial direction, and a thrust bearing portion that supports the axial member in the thrust direction. The radial bearing portion is composed of a dynamic pressure bearing in which a dynamic pressure generating portion such as a dynamic pressure groove is provided on one of two surfaces facing each other through a radial bearing gap, while the thrust bearing portion has a thrust bearing gap. And a so-called pivot bearing in which one end of the shaft member is contacted and supported by a thrust receiver. May be.

  For example, a hydrodynamic bearing device in which both a radial bearing portion and a thrust bearing portion are composed of hydrodynamic bearings exhibits particularly excellent characteristics in terms of rotational accuracy, but the required level of processing accuracy of each member and assembly accuracy between members is low. The expensive part is generally expensive. On the other hand, if the radial bearing portion is constituted by a dynamic pressure bearing and the thrust bearing portion is constituted by a pivot bearing, the processing accuracy of the members constituting the thrust bearing portion is reduced, so that the cost is reduced. .

Here, as a hydrodynamic bearing device in which a radial bearing portion is constituted by a dynamic pressure bearing and a thrust bearing portion is constituted by a pivot bearing, for example, one disclosed in Japanese Patent Application Laid-Open No. 2004-263707 (Patent Document 1) is known. . In the hydrodynamic bearing device disclosed in this document, a shaft member is fitted to a shaft portion having one end formed in a convex spherical shape and an outer periphery of the shaft portion, and is axially connected to a bearing sleeve (“radial bearing” in the document). It is comprised with the flange part ("shaft retaining member" in literature) to engage. For this reason, it is possible to effectively prevent the shaft member from coming off from the bearing sleeve, which is particularly problematic when the thrust bearing portion is constituted by a pivot bearing.
JP 2004-263707 A

  However, as described above, in the structure in which the ring-shaped flange portion is fitted to the shaft portion whose one end is formed in a convex spherical shape, assembling accuracy (for example, coaxiality) between the shaft portion and the flange portion is ensured or It becomes difficult to maintain. For example, it is assumed that desired assembly accuracy is not ensured due to the dimensional tolerance of each part, or that the assembly accuracy between the flange portion and the convex ball portion is lowered due to sliding contact with other members. As described above, when the assembly accuracy of the shaft portion and the flange portion is insufficient, there is a possibility that problems such as unbalance occur when the shaft member rotates, and the desired bearing performance cannot be obtained.

  The subject of this invention is avoiding the fall of the assembly | attachment precision between a shaft part and a flange part in this kind of hydrodynamic bearing apparatus.

  In order to solve the above problems, in the present invention, a shaft member having a shaft portion and a flange portion, a bearing sleeve that is disposed on the outer periphery of the shaft member and rotates relative to the shaft member, an outer peripheral surface of the shaft portion, and an inner surface of the bearing sleeve are provided. A radial bearing gap formed between the circumferential surface and a radial bearing section having a dynamic pressure generating section for generating a dynamic pressure action of fluid in the radial bearing gap; and a thrust receiver for contacting and supporting the shaft member in the thrust direction; In a hydrodynamic bearing device having a restriction portion that engages with a flange portion of a shaft member in an axial direction and restricts removal of the shaft member, of the shaft member, a flange portion and a sliding portion that contacts the thrust receiver, A hydrodynamic bearing device characterized in that is integrally formed.

  As described above, by integrally forming the sliding part and the flange part, the sliding part and the flange part can be processed simultaneously using the same processing standard, so both are manufactured separately from different materials. Thus, it is possible to avoid a decrease in assembly accuracy (for example, coaxiality) that becomes a problem when assembled. Thus, for example, when the shaft member is rotated and used, it is possible to prevent the flange portion from being an unbalanced load generation source, and the rotation accuracy of the shaft member is increased.

  The shaft member having the above configuration is formed by forging an integrated product of a flange portion and a sliding portion, for example, and then integrally joined with a shaft portion separately manufactured by means such as welding, friction welding, adhesion, etc. Can be manufactured. In this way, if the integral part of the flange part and the sliding part is formed by forging, the problem of increasing costs due to an increase in material loss, which becomes a problem when manufacturing this by machining such as cutting, is effective. Can be avoided and desirable.

  In addition to the flange portion and the sliding portion, the shaft member may be one in which the shaft portion is integrally formed. With such a configuration, high fastening strength is ensured between the shaft portion and the flange portion, and it is possible to reliably prevent the shaft member from being pulled out, as well as not causing deterioration in assembly accuracy. Even if it is a case where it is such a structure, if each part of a shaft member is shape | molded integrally by forging, the problem of a cost increase can be avoided effectively.

  The sliding portion has a shape in which the diameter of the thrust receiving side is gradually reduced. This sliding portion may be provided in a partial region of the end surface of the flange portion, or may be provided in the entire region of the end surface of the flange portion. When the former configuration is adopted, a flat surface remains on the end surface of the flange portion. Therefore, this flat surface can be used as a receiving surface for the jig, and finishing processing (for example, grinding) of the outer peripheral surface of the shaft portion is used for the latter. There is an advantage that it can be easily performed. On the other hand, when the latter configuration is adopted, the radius of curvature of the sliding portion can be made larger than that of the former without increasing the axial dimension of the sliding portion. Therefore, when a rotating member such as a disk hub is mounted on the shaft portion or when an impact load is applied to the bearing device, the pressing force applied to the thrust receiver via the sliding portion can be reduced. There is a merit that damage to the thrust receiver can be effectively prevented.

  In the above configuration, the bearing sleeve can be fixed to the inner periphery of a separately provided housing, and this housing can be injection-molded with a thrust receiver as an insert part. With this configuration, it becomes easy to satisfy different required characteristics in each part of the housing, and such a housing can be obtained at low cost.

  As described above, according to the present invention, in the hydrodynamic bearing device in which the thrust load is contact-supported and the shaft member is prevented from coming off by the flange portion, the assembly accuracy between the shaft portion and the flange portion is reduced. Can be avoided, and high rotational accuracy can be stably maintained over a long period of time.

  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 hydrodynamic bearing device. This spindle motor is used in a disk drive device such as an HDD, and includes a hydrodynamic bearing device 1 that rotatably supports a shaft member 2, a disk hub 3 provided at one end of the shaft member 2, and a radial direction, for example. The stator coil 4a and the rotor magnet 4b, which are opposed to each other through the gap, and the 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 housing 7 of the hydrodynamic bearing device 1 is mounted on the inner periphery of the bracket 5. One or a plurality of disks 6 such as magnetic disks (two in the illustrated example) are held on the disk hub 3. 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 disk 6 held thereby are integrated with the shaft member 2. Rotate.

  FIG. 2 shows the hydrodynamic bearing device 1 according to the first embodiment of the present invention. The hydrodynamic bearing device 1 shown in FIG. 1 seals a shaft member 2, a bearing sleeve 8 disposed on the outer periphery of the shaft member 2, a housing 7 that fixes the bearing sleeve 8 to the inner periphery, and one end opening of the housing 7. And a sealing member 9 to be provided as a main component. For convenience of explanation, the following explanation will be made with the seal member 9 side as the upper side and the opposite side in the axial direction as the lower side.

  The housing 7 is made of a metal material or a resin material, and is formed in a bottomed cylindrical shape (cup shape) in which a cylindrical side portion in which the bearing sleeve 8 is fixed to the inner periphery and a disc-shaped bottom portion are integrated. The inner peripheral surface of the housing 7 is divided into a large-diameter inner peripheral surface 7a and a small-diameter inner peripheral surface 7b in the axial direction, and both the inner peripheral surfaces 7a and 7b pass through a flat step surface 7d in a direction perpendicular to the axis. Connected. In this embodiment, the disk-shaped bottom part functions as the “thrust receiver” in the present invention, and the inner bottom surface 7c of the bottom part is a smooth flat surface.

  The bearing sleeve 8 is formed of a sintered metal porous body mainly composed of copper, for example, in a cylindrical shape, and the lower end surface 8b is brought into contact with the stepped surface 7d of the housing 7 so that the large diameter of the housing 7 is reached. For example, it is fixed to the inner peripheral surface 7a by an appropriate means such as adhesion, press-fitting, or welding. In the present embodiment, the lower end surface 8b of the bearing sleeve 8 functions as a “restricting portion” in the present invention, and a flange portion 22 of the shaft member 2 described later is engaged in the restricting portion (lower end surface 8b) in the axial direction. By combining, the removal of the shaft member 2 is restricted. In addition to the sintered metal, the bearing sleeve 8 can be formed of a soft metal material such as brass or another porous body (for example, a porous resin) that is not a sintered metal.

  As shown in FIG. 3, a region where a plurality of dynamic pressure grooves 8a1 and 8a2 are arranged in a herringbone shape is formed on the inner peripheral surface 8a of the bearing sleeve 8 at two upper and lower positions, as shown in FIG. The In the present embodiment, the upper dynamic pressure groove 8a1 is formed axially asymmetric with respect to the axial center m (the axial center of the upper and lower inclined groove regions), and the axis in the upper region from the axial center m. The direction dimension X1 is larger than the axial direction dimension X2 of the lower region. 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. The dynamic pressure groove may be formed on the outer peripheral surface 21a of the shaft portion 21 constituting the shaft member 2, and the shape thereof may be other known shapes such as a spiral shape.

  The outer peripheral surface 8c of the bearing sleeve 8 is formed with one or a plurality of axial grooves 8c1 opened at both end surfaces. In addition, one or a plurality of radial grooves 8b1 are formed on the outer diameter side of the lower end surface 8b of the bearing sleeve 8. The grooves 8b1 and 8c1 form a fluid passage which will be described later between the stepped surface 7d and the large-diameter inner peripheral surface 7a of the opposing housing 7, and are not necessarily provided in the bearing sleeve 8; 7 may be provided on each surface 7d, 7a.

  The seal member 9 is formed in a ring shape from, for example, a soft metal material such as brass, other metal materials, or a resin material, and is appropriately bonded or press-fitted to the upper end portion of the large-diameter inner peripheral surface 7a of the housing 7. It is fixed with. A predetermined seal space S is formed between the inner peripheral surface 9 a of the seal member 9 and the outer peripheral surface 21 a of the shaft portion 21. One or more radial grooves 9b1 are formed on the lower end surface 9b of the seal member 9. The radial groove may be provided on the upper end surface of the bearing sleeve 8 facing the radial groove.

  The shaft member 2 includes a shaft portion 21, a disc-shaped flange portion 22 that projects to the outer diameter side of the shaft portion 21, and a sliding portion 23 that protrudes downward at the shaft center portion of the flange portion 22. In the present embodiment, the sliding portion 23 is a partial area on the inner diameter side of the lower end surface 22b of the flange portion 22 and has a hemispherical shape that is gradually reduced in diameter toward the lower side. 7 contacts the inner bottom surface 7c at one point. The outer peripheral surface 21a of the shaft portion 21 is a smooth cylindrical surface having substantially the same diameter except that the substantially central portion in the axial direction is formed with a smaller diameter than other portions.

  Of the shaft member 2, the flange portion 22 and the sliding portion 23 are integrally formed by forging using stainless steel. And the shaft member 2 as a finished product is obtained by fixing the flange portion 22 to the lower end of the stainless steel shaft portion 21 manufactured separately by means such as welding, friction welding, adhesion or the like.

  The shaft portion 21 is inserted into the inner periphery of the bearing sleeve 8, while the flange portion 22 and the sliding portion 23 are formed with a small-diameter inner peripheral surface 7 b of the housing 7, an inner bottom surface 7 c of the housing 7, and a lower end surface of the bearing sleeve 8. It is accommodated in the space formed by 8b. The flange portion 22 is engaged with the lower end surface 8b of the bearing sleeve 8 as a restricting portion in the axial direction, and thereby the shaft member 2 is effectively prevented from coming off from the bearing sleeve 8.

  The hydrodynamic bearing device 1 is mainly composed of the above-described components, and the internal space of the housing 7 sealed by the seal member 9 is filled with lubricating oil as a lubricating fluid including the internal pores of the bearing sleeve 8.

  In the hydrodynamic bearing device 1 having the above configuration, when the shaft member 2 rotates, the hydrodynamic groove 8a1 and 8a2 formation region of the bearing sleeve 8 is opposed to the outer peripheral surface 21a of the shaft portion 21 via the radial bearing gap. . As the shaft member 2 rotates, the oil film formed in the radial bearing gap is enhanced in its rigidity by the dynamic pressure action of the dynamic pressure grooves 8a1 and 8a2, and the shaft member 2 rotates in the radial direction by this pressure. It is supported non-contact freely. As a result, radial bearing portions R1 and R2 that support the shaft member 2 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 shaft member 2 rotates, the lower end surface of the shaft member 2 (spherical surface 23a of the convex sliding portion 23) is contact-supported by the inner bottom surface 7c of the housing 7 (bottom portion). As a result, a thrust bearing portion T composed of a pivot bearing that rotatably supports the shaft member 2 in the thrust direction is formed.

  In addition, when the shaft member 2 rotates, as described above, the seal space S has a tapered shape that gradually decreases toward the inside of the housing 7, so that the lubricating oil in the seal space S is drawn by capillary force. By the action, the seal space is drawn in the direction of narrowing, that is, toward the inside of the housing 7. Thereby, the leakage of the lubricating oil from the inside of the housing 7 is effectively prevented. Further, the seal space S has a buffer function for absorbing a volume change amount accompanying a temperature change of the lubricating oil filled in the internal space of the housing 7, and the oil level of the lubricating oil is within a range of the assumed temperature change. Is always in the seal space S.

  Further, as described above, 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 direction of the lower region. It is larger than the dimension X2 (see FIG. 3). Therefore, when the shaft member 2 rotates, the lubricating oil pulling force (pumping force) by the dynamic pressure groove 8a1 is relatively larger in the upper region than in the lower region. Then, due to the differential pressure of the pulling force, the lubricating oil filled in the gap between the inner peripheral surface 8a of the bearing sleeve 8 and the outer peripheral surface 21a of the shaft portion 21 flows downward, and the lower end surface of the bearing sleeve 8 8b and the gap between the upper end surface 22a of the flange portion 22 → the fluid passage formed by the radial groove 8b1 of the bearing sleeve 8 → the fluid passage formed by the axial groove 8d1 of the bearing sleeve 8 → the diameter of the seal member 9 It circulates through a path called a fluid passage formed by the direction groove 9b1, and is drawn again into the radial bearing gap of the first radial bearing portion R1.

  In this way, by configuring the lubricating oil to flow and circulate in the internal space of the housing 7, the pressure balance of the lubricating oil is maintained, and at the same time, the generation of bubbles accompanying the generation of local negative pressure, Problems such as leakage of lubricating oil and generation of vibration due to generation can be solved. Since the sealing space S communicates with the above circulation path, even if bubbles are mixed in the lubricating oil for some reason, when the bubbles circulate with the lubricating oil, the lubricating oil in the sealing space S It is discharged from the oil surface (gas-liquid interface) to the outside air. Therefore, adverse effects due to air bubbles can be more effectively prevented.

  As described above, if the flange portion 22 and the sliding portion 23 constituting the shaft member 2 are integrally formed, the sliding portion 23 and the flange portion 22 can be simultaneously processed using the same processing standard. Therefore, it is possible to avoid a decrease in assembly accuracy (for example, coaxiality), which becomes a problem when both are manufactured separately and assembled from different materials. As a result, when the shaft member 2 is rotated and used as described above, it is possible to prevent the flange portion 22 from being an unbalanced load generation source, and the rotation accuracy of the shaft member 2 is increased. This also reduces the possibility of unexpected sliding contact between the upper end surface 22a of the flange portion 22 and the lower end surface 8b of the bearing sleeve 8, and contamination caused by wear of the flange portion 22 or the bearing sleeve 8 is reduced. The problem is effectively resolved. From the above, according to the present invention, high rotational accuracy can be maintained over a long period of time.

  In addition, since the flange portion 22 and the sliding portion 23 are integrally formed by forging, a highly accurate integrated product can be obtained at a lower cost than when the flange portion 22 and the sliding portion 23 are integrally formed by machining such as cutting.

  In addition, since the sliding portion 23 is provided in a partial area on the inner diameter side of the lower end surface 22b of the flange portion 22, a flat smooth surface remains on the outer diameter side of the lower end surface 22b of the flange portion 22. The lower end surface 22b of the flange portion 22 is used as a receiving surface for a jig when, for example, the outer peripheral surface 21a of the shaft portion 21 is subjected to a finishing process such as grinding after the shaft portion 21 and the flange portion are integrated. . At this time, as described above, if a flat smooth surface remains on the lower end surface 22b, the jig shape can be simplified, and finishing can be performed easily and at low cost.

  In the above description, the configuration using the shaft member 2 in which the shaft portion 21 manufactured individually, the flange portion 22 and the sliding portion 23 are coupled and integrated by appropriate means has been described. 21, the flange portion 22, and the sliding portion 23 can be integrally formed. With this configuration, compared to the configuration described above, the fastening strength between the shaft portion 21 and the flange portion 22 can be further increased, so that the shaft member 2 can be more reliably prevented from being detached. Thus, when all the parts of the shaft member 2 are integrally formed, there is a concern about an increase in manufacturing cost, but by forging the shaft member 2 having such a configuration, the increase in cost is suppressed as much as possible.

  As mentioned above, although the hydrodynamic bearing apparatus 1 which concerns on one Embodiment of this invention was demonstrated, this invention is not limitedly applied to the hydrodynamic bearing apparatus 1 of the said structure, The hydrodynamic bearing apparatus shown below is also applied. It can be preferably applied. In the following, from the viewpoint of simplifying the description, the same reference numerals are assigned to the configurations according to the embodiment shown in FIG.

  FIG. 4 shows a second embodiment of the hydrodynamic bearing device according to the present invention. The hydrodynamic bearing device 1 shown in the figure is different from that shown in FIG. 2 in that a sliding portion 23 is provided in the entire region of the lower end surface of the flange portion 22. With this configuration, the radius of curvature of the sliding portion 23 can be increased compared to the configuration shown in FIG. 2 without increasing the axial dimension of the sliding portion 23. Therefore, when the disk hub 3 is press-fitted into the shaft portion 21 or when an impact load is applied to the hydrodynamic bearing device 1, a thrust receiver (here, the housing 7) The pressing force applied to the bottom portion can be reduced, and damage to the thrust receiver can be effectively prevented.

  2, when the same housing 7 as in FIG. 2 is used, the space formed between the housing 7 and the shaft member 2 is increased as the volume of the sliding portion 23 increases. Compared to the configuration shown in FIG. Therefore, the amount of lubricating oil to be filled in the bearing can be reduced, that is, the volume of the seal space S can be reduced, and the dynamic pressure bearing device 1 can be made compact.

  FIG. 5 shows a third embodiment of the hydrodynamic bearing device according to the present invention. The main difference of the hydrodynamic bearing device shown in FIG. 2 from that shown in FIG. 2 is that the housing 7 comes into contact with the sliding portion 23 of the shaft member 2 (forms a thrust bearing portion T), This is in that it is formed of an insert part and a main body 71 having a bearing sleeve 8 fixed to the inner periphery. In the illustrated example, the shaft member 2 similar to that in the embodiment shown in FIG. 2 is used. However, it is of course possible to use the same shaft member 2 as that in the embodiment shown in FIG.

  By the way, for example, the main body 71 of the housing 7 is preferably made of resin or light alloy from the viewpoint of reducing the weight of the hydrodynamic bearing device 1, whereas the sliding portion 23 of the shaft member 2 is preferable. In some cases, it is desirable that the thrust receiver 72 for contacting and supporting is formed of stainless steel or the like in consideration of wear resistance. In this regard, if the housing 7 is configured with the thrust receiver 72 and the main body portion 71 different from the thrust receiver 72 as in the present embodiment, each portion of the housing 7 is compared with the case where the housing 7 is formed of a single material. Different required characteristics can be easily satisfied. Thus, when the housing 7 is composed of two articles, the manufacturing cost may increase. However, if the main body 71 is injection-molded by inserting the thrust receiver 72, the cost increase can be effectively suppressed. is there.

  Examples of resin materials that can be used for injection molding of the main body 71 include crystalline resins such as liquid crystal polymer (LCP), polyether ether ketone (PEEK), polybutylene terephthalate (PBT), and polyphenylene sulfide (PPS). Other examples include amorphous resins such as polysulfone (PSU), polyethersulfone (PES), polyphenylsulfone (PPSU), and polyetherimide (PEI). These resin materials can be used alone or in combination of two or more. Moreover, if necessary, one or more kinds of various fillers for imparting various properties can be added.

  Moreover, as a metal material which can be used for injection molding of the main-body part 71, low melting-point metals, such as a magnesium alloy and an aluminum alloy, are mentioned, for example. The main body 71 can also be molded by so-called MIM molding in which a mixture of metal powder and binder is injection molded and then degreased and sintered.

  FIG. 6 shows a fluid dynamic bearing device 1 according to a fourth embodiment of the present invention. The main difference between the hydrodynamic bearing device 1 shown in the figure and the hydrodynamic bearing device shown above is that the shaft member 2 uses the shaft portion 21 as an insert part, and the flange portion 22 and the sliding portion 23 are integrally injected. It is in the point where it is molded. In addition, the flange part 22 and the sliding part 23 can be injection-molded using the resin used for shaping | molding of the main-body part 71 of the housing 7 mentioned above, or a metal.

  In the shaft member 2 shown in the figure, a concave portion 21b is provided on the lower end axis of the shaft portion 21, and a fastening portion for preventing the flange portion 22 from coming off and rotating is formed in the concave portion 21b. Yes. In the illustrated example, the fastening portion is composed of a tapered surface that is gradually reduced in diameter downward, and one or more axial grooves (not shown) provided on the tapered surface.

  The function of preventing the fastening portion from coming off can be obtained by anchoring the flange portion 22 (the upper end portion thereof) to the shaft portion 21 so as to resist the axial pulling force acting on the flange portion 22. The function as a detent can be obtained by forming the recess 21b in a shape that can regulate the relative rotation of the shaft portion 21 and the flange portion 22. From this point of view, for example, the form shown in FIGS. 7A and 7B can be adopted as the form of the fastening part to be provided in the recess 21b in addition to the above. FIG. 7A shows a recess 21b in which a fastening portion including one or a plurality of axial grooves and a plurality of rows of circumferential grooves parallel to each other is formed, and FIG. 7B shows a fastening portion formed of a screw groove. Each of the recesses 21b is formed. Of course, the form of the fastening portion to be provided in the concave portion 21b is arbitrary as long as the retaining function and the anti-rotation function can be obtained. For example, it can be configured by providing a plurality of depressions (dimples) on the inner wall surface of the concave portion 21b. .

  Such a configuration (the configuration shown in FIG. 6) is used when the shaft member 2 (dynamic pressure) is not required between the shaft portion 21 and the flange portion 22 when a strong fastening force is not required as in the case where the two portions are integrally formed. This is effective in reducing the cost and weight of the bearing device 1).

  In the above, the configuration in which the dynamic pressure action of the lubricating oil is generated by the dynamic pressure grooves of the herringbone shape or the like is illustrated as the radial bearing portions R1 and R2, but the radial bearing portions R1 and R2 are so-called step bearings, An arc bearing or a non-circular bearing may be employed. Moreover, although the structure which provided the radial bearing part in the axial direction two places was illustrated above, a radial bearing part can also be provided in the axial direction one place or three places or more.

  In the above description, 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.

  Further, the hydrodynamic bearing device 1 according to the present invention can be used not only as a spindle motor bearing as described above but also as a fan motor bearing mounted on a PC or the like for cooling a heat source. It is. When the hydrodynamic bearing device 1 is used as a fan motor bearing, a rotor having blades (fans) is provided at the upper end of the shaft portion 21 instead of the disk hub 3.

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. It is sectional drawing of a bearing sleeve. 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. It is sectional drawing which shows 4th Embodiment of the hydrodynamic bearing apparatus which concerns on this invention. 6A is a cross-sectional view showing another configuration example of the lower end of the shaft portion in the embodiment shown in FIG. 6, and FIG. 6B is another configuration of the lower end of the shaft portion in the embodiment shown in FIG. It is sectional drawing which shows an example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Dynamic pressure bearing apparatus 2 Shaft member 21 Shaft part 22 Flange part 23 Sliding part 3 Disc hub 7 Housing 71 Main body part 72 Thrust receiver 8 Bearing sleeve 9 Seal member R1, R2 Radial bearing part T Thrust bearing part

Claims (6)

A shaft member having a shaft portion and a flange portion, a bearing sleeve disposed on the outer periphery of the shaft member and rotating relative to the shaft member, and a radial bearing formed between the outer peripheral surface of the shaft portion and the inner peripheral surface of the bearing sleeve A radial bearing portion having a dynamic pressure generating portion for generating a fluid dynamic pressure action in the clearance and the radial bearing clearance, a thrust receiver for contacting and supporting the shaft member in the thrust direction, and an axial engagement with the flange portion of the shaft member Then, in the hydrodynamic bearing device having a regulating portion that regulates the removal of the shaft member,
A hydrodynamic bearing device characterized in that, among the shaft members, a flange portion and a sliding portion that contacts the thrust receiver are integrally formed.   2. The hydrodynamic bearing device according to claim 1, wherein the shaft portion, the flange portion, and the sliding portion of the shaft member are integrally formed.   The hydrodynamic bearing device according to claim 1 or 2, wherein the shaft member is formed by forging.   The hydrodynamic bearing device according to claim 1, wherein the sliding portion has a shape in which the diameter of the thrust receiving side is gradually reduced, and the sliding portion is provided in a partial region of the end surface of the flange portion.   The hydrodynamic bearing device according to claim 1, wherein the sliding portion has a shape in which the diameter of the thrust receiving side is gradually reduced, and the sliding portion is provided in the entire area of the end surface of the flange portion.   2. The hydrodynamic bearing device according to claim 1, wherein the bearing sleeve is fixed to the inner periphery of the housing, and the housing is injection-molded with a thrust receiver as an insert part.

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