JP2006194384A - Dynamic pressure bearing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a dynamic pressure bearing device with a cover member to be efficiently and precisely installed on a housing. <P>SOLUTION: On the cover member 10 having a thrust bearing face 11a forming a thrust bearing gap between a lower side end face 2b2 of a flange portion 2b of a shaft member 2 and itself, an abutting face 12a is formed for abutting with a lower side end face 8c of a sleeve member 8. An adhesive sump C1 is formed between an outer peripheral face 10a of the cover member 10 and an inner peripheral face 7a of the housing 7 opposed thereto. Adjacent to the adhesive sump C1 on the upper end side (the bearing inside) of the adhesive sump C1, an adhesion gap C4 is formed which has a smaller radial gap than the adhesive sump C1. <P>COPYRIGHT: (C)2006,JPO&amp;NCIPI

Description

  The present invention relates to a hydrodynamic bearing device that generates pressure by a hydrodynamic action of fluid generated in a bearing gap and supports a shaft member in a non-contact manner. This bearing device is a spindle motor such as an information device, for example, a magnetic disk device such as an HDD, an optical disk device such as a CD-ROM, CD-R / RW, DVD-ROM / RAM, or a magneto-optical disk device such as MD or MO, It is suitable for polygon scanner motors of laser beam printers (LBP) and other small motors.

  In addition to high rotational accuracy, the various motors are required to have high speed, low cost, low noise, and the like. One of the components that determine the required performance is a bearing that supports the spindle of the motor. In recent years, the use of a hydrodynamic bearing having characteristics excellent in the required performance has been studied or actually used. Yes.

For example, in a hydrodynamic bearing device incorporated in a spindle motor of a disk drive device such as an HDD, both the radial bearing portion that supports the shaft member in the radial direction and the thrust bearing portion that supports the axial direction in the thrust direction are configured by the hydrodynamic bearing. There is. As a thrust bearing portion in this type of hydrodynamic bearing device, any one of a flange portion end surface of the shaft member and a surface facing this, for example, an end surface (thrust receiving surface) of a lid member that seals the opening of the bearing member On the other hand, for example, a dynamic pressure generating portion such as a dynamic pressure groove is formed, and a thrust bearing gap is formed between both end faces (for example, see Patent Document 1). The lid member has a plate shape, and is fixed to one end opening of the bearing member by means such as adhesion (see, for example, Patent Document 2).
JP 2003-239951 A JP 2003-343562 A

  When the lid member is bonded and fixed to the bearing member, usually, the lid member is press-fitted into one end opening of the bearing member and temporarily fixed, and then an adhesive is supplied to the radial gap between the two members.

  Incidentally, in the structures described in Patent Documents 1 and 2, the axial position of the lid member with respect to the bearing member determines the width dimension accuracy of the thrust bearing gap. Therefore, when temporarily fixing the lid member to the opening of the bearing member, it is necessary to accurately manage the temporary fixing position of the lid member using a jig or the like, and the process becomes complicated.

  Therefore, an object of the present invention is to provide a dynamic pressure bearing device capable of efficiently and highly accurately assembling the lid member to the bearing member.

  In order to solve the above-described problems, a hydrodynamic bearing device according to the present invention includes a bearing member, a shaft member that is inserted into the inner periphery of the bearing member and rotates relative to the bearing member, and a fluid generated in a thrust bearing gap. A thrust receiver that generates a pressure by dynamic pressure action and supports the shaft member in a non-contact manner in the thrust direction, and a thrust bearing that is bonded and fixed to one end of the bearing member and that forms a thrust bearing gap between the end surface of the shaft member. In the hydrodynamic bearing device including a lid member having a surface, the lid member is provided with a contact surface having an axial step between the thrust receiving surface and abutting the bearing member in the axial direction. An adhesive reservoir is formed between the lid member and the bearing member facing the lid member, and an adhesive gap having a radial gap narrower than the adhesive reservoir is formed adjacent to the adhesive reservoir. To do.

  As described above, according to the present invention, the lid member is provided with a contact surface having a step in the axial direction with respect to the thrust receiving surface that forms a thrust bearing gap with the end surface of the shaft member. It abuts on the bearing member in the axial direction. Therefore, when the cover member is assembled to the bearing member, the cover member can be easily attached to the bearing member by simply pushing the cover member in the axial direction until the contact surface contacts the bearing member without using a positioning jig. Furthermore, the thrust receiving surface can be positioned in the axial direction, and a highly accurate thrust bearing gap can be formed.

  Thus, after positioning the cover member in the axial direction with respect to the bearing member, the cover member is bonded and fixed to the bearing member by the adhesive supplied to the gap between the cover member and the bearing member facing the cover member. As a method of supplying the adhesive to the gap, for example, a method of applying the adhesive to the surface of the bearing member facing the lid member in advance and then pushing the lid member to the axial contact position, or an axial contact For example, a method of injecting an adhesive into the gap from the outside of the bearing after the lid member is pushed to the position can be considered.

  However, in the former method, as the lid member is pushed in, the applied adhesive is inevitably scraped forward in the pushing direction of the lid member. Therefore, depending on the application state of the adhesive, the adhesive uniformly passes through the gap. It may not arrive. In the latter method, since the gap between the lid member and the bearing member facing the lid member is very narrow, the adhesive is applied from the outside opening side to the back side (the contact portion side between the lid member and the bearing member) of the gap. It is difficult to get it fully. If the adhesive is not uniformly filled, there is a possibility that a stable fixing force cannot be obtained between the two members. Further, if there is an unfilled portion of the adhesive in the gap, there is a possibility that oil filled inside the bearing leaks out of the bearing.

  Therefore, in the present invention, an adhesive reservoir is formed between the lid member and the bearing member facing the lid member, and an adhesive gap is formed adjacent to the adhesive reservoir and having a narrower radial gap than the adhesive reservoir. did. According to this, since the adhesive once accumulated in the adhesive reservoir is drawn into the adhesive gap narrower than the adhesive reservoir by a pulling force such as capillary force, the adhesive reaches the adhesive gap evenly without leaking. You can make it. Thereby, the space | interval between a cover member and a shaft member is completely sealed, and the situation where the oil inside a bearing leaks outside from the unfilled location of an adhesive agent can be avoided. Moreover, a required fixing force can be stably obtained between both members because the adhesive is uniformly filled in the adhesive gap without leakage. Further, since the adhesive stored in the adhesive reservoir is engaged with the lid member in the axial direction in the solidified state, it also acts as a retaining member for the lid member.

  The adhesive reservoir can be connected to the adhesive gap through, for example, a tapered space. According to this, since the flow of the adhesive from the adhesive reservoir to the adhesive gap is performed more smoothly, the adhesive gap can be more reliably filled with the adhesive.

  For example, a holding space for holding an adhesive can be formed in the opening of the bonding gap. According to this, for example, the supply amount of the adhesive becomes excessive, and the adhesive that cannot be held in the adhesive gap is forward from the opening of the adhesive gap in the direction of insertion of the lid member (the contact portion side between the lid member and the bearing member). When it is about to overflow, the excess adhesive is captured in the holding space and held in the holding space. Therefore, the overflowing adhesive can be prevented from entering between the contact surface of the lid member and the bearing member in contact with the lid member, and the axial positioning of the lid member can be performed with high accuracy. Even if a circulation groove for smooth fluid circulation inside the bearing or a dynamic pressure groove is formed at the contact portion of the bearing member that contacts the contact surface of the lid member, By holding the excess adhesive, it is possible to avoid a situation where the adhesive overflowing forward in the insertion direction of the lid member blocks these grooves.

  For example, the holding space may have a shape in which the radial dimension is reduced toward the bonding gap. According to this configuration, the adhesive that tends to overflow from the adhesive gap to the front in the insertion direction of the lid member (the contact portion side of the lid member and the bearing member) is drawn into the adhesive gap side by the capillary force generated in the holding space. It is. Therefore, it can prevent more reliably that an adhesive agent penetrate | invades between both members which mutually contact | abut.

  Between the lid member and the bearing member facing the lid member, for example, an adhesive gap is formed on one axial end side of the adhesive reservoir, and a press-fitting portion between the lid member and the bearing member is provided on the other axial end side. be able to. Alternatively, it is possible to adopt a configuration in which the adhesive gap is formed at both axial ends of the adhesive reservoir.

  The bearing member can also include, for example, a sleeve member that faces the radial bearing gap and a housing that fixes the sleeve member to the inner periphery. In this case, the contact surface of the lid member contacts the axial end surface of the sleeve member.

  The above-described hydrodynamic bearing device can be provided as a motor including, for example, a hydrodynamic bearing device, a rotor magnet, and a stator coil.

  Thus, according to the present invention, it is possible to set the thrust bearing gap of this type of hydrodynamic bearing device with high accuracy and simplicity by suppressing the overflow of the adhesive from the adhesion gap.

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

  FIG. 1 conceptually shows a configuration example of a spindle motor for information equipment incorporating a fluid dynamic bearing device 1 according to an embodiment of the present invention. This spindle motor for information equipment is used in a disk drive device such as an HDD, and is attached to the dynamic pressure bearing device 1 for supporting the shaft member 2 in a non-contact manner rotatably with respect to the bearing member, and the shaft member 2. The disk hub 3 is provided with a stator coil 4 and a rotor magnet 5 which are opposed to each other through a radial gap, for example, and a bracket 6. The stator coil 4 is attached to the outer periphery of the bracket 6, and the rotor magnet 5 is attached to the inner periphery of the disk hub 3. The bracket 6 has the hydrodynamic bearing device 1 mounted on the inner periphery thereof. The disk hub 3 holds one or more disk-shaped information recording media (hereinafter simply referred to as disks) D such as magnetic disks on the outer periphery thereof. In the spindle motor for information equipment configured as described above, when the stator coil 4 is energized, the rotor magnet 5 is rotated by the magnetic force between the stator coil 4 and the rotor magnet 5, and accordingly, the disk hub 3 and the disk The disk D held by the hub 3 rotates integrally with the shaft member 2.

  FIG. 2 shows the hydrodynamic bearing device 1. The hydrodynamic bearing device 1 includes a housing 7 and a sleeve member 8 that constitute a bearing member, a lid member 10 that seals one end opening of the housing 7, and a shaft member 2 that is inserted into the inner periphery of the sleeve member 8. Mainly prepared. For convenience of explanation, the following description will be given with the side of the lid member 10 that seals one end of the housing 7 being the lower side and the side opposite to the lid member 10 being the upper side.

  The shaft member 2 is made of, for example, a metal material such as stainless steel, or has a hybrid structure of a metal material and a resin material, and is provided integrally or separately at the lower end of the shaft portion 2a and the shaft portion 2a. A flange portion 2b is provided.

  The sleeve member 8 is made of, for example, a soft metal material such as copper or aluminum (aluminum alloy), or a sintered metal material. In this embodiment, the sleeve member 8 is formed in a cylindrical shape with a porous body made of sintered metal, in particular, a sintered metal porous body mainly composed of copper, and is formed on an inner peripheral surface 7a of the housing 7 to be described later. Fixed.

  A dynamic pressure groove as a radial dynamic pressure generating portion is formed on the entire inner surface 8a of the sleeve member 8 or a partial cylindrical region. In this embodiment, herringbone-shaped dynamic pressure grooves 8a1 and 8a2 shown in FIG. 3A, for example, are formed at two locations in the axial direction. In the formation region of the upper dynamic pressure groove 8a1, the dynamic pressure groove 8a1 is formed to be axially asymmetric with respect to the axial center m (the axial center of the upper and lower inclined groove regions). The axial dimension X1 of the upper region is larger than the axial dimension X2 of the lower region.

  One or a plurality of axial grooves 8b1 are formed on the outer peripheral surface 8b of the sleeve member 8 over the entire length in the axial direction. In this embodiment, three axial grooves 8b1 are formed at equal intervals in the circumferential direction.

  For example, as shown in FIG. 3B, a spiral dynamic pressure groove 8c1 is formed as a thrust dynamic pressure generating portion on the entire or a part of the annular region of the lower end surface 8c of the sleeve member 8.

  As shown in FIG. 3A, a circumferential groove 8d1 having a V-shaped cross section is formed over the entire circumference of the upper end surface 8d of the sleeve member 8 at a substantially central portion in the radial direction. One or a plurality of radial grooves 8d2 are formed in the inner diameter side region of the upper end face 8d defined by the circumferential groove 8d1. The radial groove 8d2 communicates between the circumferential groove 8d1 and the upper end of the inner peripheral surface 8a of the sleeve member 8 when the sleeve member 8 is in axial contact with the seal portion 9 as shown in FIG. To do.

  The housing 7 is injection-molded in a cylindrical shape with a resin composition containing, for example, liquid crystal polymer (LCP), polyphenylene sulfide (PPS), polyetheretherketone (PEEK), or the like as a base resin. As shown in FIG. 2, a seal portion 9 is formed integrally with the housing 7 on the inner diameter side of the upper end of the housing 7.

  As shown in FIG. 2, the lid member 10 has a shape in which the outer peripheral portion of the disk-shaped bottom portion 11 protrudes in the axial direction, and is integrally formed of a metal material, preferably a soft metal such as brass. An annular thrust receiving surface 11 a is formed on the end surface of the bottom portion 11 on the inner diameter side of the outer peripheral protruding portion 12 in the lid member 10. On the thrust receiving surface 11a, although not shown, a spiral dynamic pressure groove is formed as a thrust dynamic pressure generating portion. The axial end surface of the outer peripheral protrusion 12 is an annular contact surface 12a, which contacts the lower end surface 8c of the sleeve member 8 on the entire periphery thereof.

  A recess 10 b is formed on the outer peripheral surface 10 a of the lid member 10. In this embodiment, the concave portion 10b is located in a substantially central portion in the axial direction and is formed in an annular shape. Of the outer peripheral surface 10a defined by the concave portion 10b, the outer diameter dimension Do1 of the first outer peripheral surface 10a1 located below the concave portion 10b is slightly larger than the inner peripheral surface 7a of the housing 7 to which the lid member 10 is bonded and fixed. It is a diameter. On the other hand, the outer diameter Do2 of the second outer peripheral surface 10a2 located above the recess 10b is slightly smaller than the inner peripheral surface 7a of the housing 7. A first tapered surface 10c1 and a second tapered surface 10c2 that are adjacent to the first outer peripheral surface 10a1 and the second outer peripheral surface 10a2, respectively, and gradually increase in diameter toward both the outer peripheral surfaces 10a1 and 10a2 at both axial ends of the recess 10b. Are formed respectively. Further, a third tapered surface 10c3 is formed between the second outer peripheral surface 10a2 and the contact surface 12a. The third tapered surface 10c3 gradually increases in diameter as it goes downward.

  The lid member 10 is roughly molded by press working after the lid member 10 is roughly molded into the shape shown in FIG. 4 by cutting or the like, for example. Accordingly, the thrust receiving surface 11a and the contact surface 12a are finished with final surface accuracy, and the axial step between the both surfaces 11a and 12a is finished with the final dimensions. At this time, if a groove die corresponding to the dynamic pressure groove shape of the thrust receiving surface 11a is formed in the forming portion of the thrust receiving surface 11a of the press die, the dynamic pressure groove is formed on the thrust receiving surface 11a simultaneously with the pressing. It becomes possible.

  In this way, by forming both the thrust receiving surface 11a and the contact surface 12a of the lid member 10 by press working, it is possible to obtain a highly accurate finished surface as compared with surface finishing by cutting or the like. At this time, the press forming of the both surfaces 11a and 12a can be performed simultaneously by the forming portion provided in the common press die. Therefore, if the distance between the forming portions is managed with high accuracy, the shaft between the both surfaces 11a and 12a can be controlled. The direction step can be finished with high accuracy. Since surface finishing by press working can provide merits such as shortening the processing time and simplifying the cleaning process after processing accompanying suppressing chip generation compared to surface finishing by cutting, Productivity can be improved along with cost reduction.

  As shown in FIG. 2, the lid member 10 manufactured according to the above procedure fixes the sleeve member 8 to the inner peripheral surface 7 a of the housing 7 at a position where the sleeve member 8 contacts the lower end surface 9 a of the seal portion 9. The inner peripheral surface 7a is bonded and fixed. Specifically, the adhesive fixing of the lid member 10 is performed according to the following procedure. The shaft member 2 may be inserted into the inner periphery of the sleeve member 8 before the lid member 10 is fixed, either before or after the sleeve member 8 is fixed to the housing 7. .

  First, an adhesive is applied to a region of the inner peripheral surface 7 a of the housing 7 facing the outer peripheral surface 10 a of the lid member 10. Next, the lid member 10 applied to the lower end opening of the housing 7 is pushed forward until the contact surface 12 a contacts the lower end surface 8 c of the sleeve member 8. At this time, as shown in FIG. 5, for example, an adhesive reservoir C1 is formed between the recess 10b of the lid member 10 and the inner peripheral surface 7a of the housing 7 facing the recess 10b. Further, an adhesive holding space C2 in which the axial dimension gradually increases upward is formed between the third tapered surface 10c3 of the lid member 10 and the inner peripheral surface 7a of the housing 7 facing the third tapered surface 10c3.

  Since the first outer peripheral surface 10a1 below the recess 10b has a slightly larger diameter than the inner peripheral surface 7a of the housing 7 facing this surface, when the lid member 10 is pushed in, the first outer peripheral surface 10a1 A press-fit region C3 is formed between the peripheral surface 7a. On the other hand, the second outer peripheral surface 10a2 above the concave portion 10b is slightly smaller in diameter than the inner peripheral surface 7a of the housing 7 facing this surface. Therefore, when the lid member 10 is pushed in, the second outer peripheral surface 10a2 A gap (adhesive gap) C4 in which an adhesive can be interposed is formed between the inner peripheral surface 7a.

  As the lid member 10 moves forward, the adhesive M applied to the inner peripheral surface 7a facing the press-fitted region C3 is scraped upward, and is stored in the adhesive reservoir C1 as shown in FIG. At this time, the adhesive M in the tapered space between the second tapered surface 10c2 on the upper end side of the adhesive reservoir C1 and the inner peripheral surface 7a of the housing 7 is drawn into the adhesive gap C4 by the upward capillary force. It is. In this manner, in addition to the adhesive M applied to the inner peripheral surface 7a in advance, the adhesive M on the adhesive reservoir C1 side is drawn into the adhesive gap C4, so that the adhesive gap C4 is uniform without leakage from the adhesive M. The space between the lid member 10 and the housing 7 is completely sealed. Moreover, a required fixing force can be stably obtained between the members 10 and 7.

  When the application amount of the adhesive M to the inner peripheral surface 7a is excessive, excess adhesive M overflows from the adhesive gap C4 to the sleeve member 8 side, but the excess part is at the upper end of the adhesive gap C4. It is captured by the formed holding space C2 and is held in this holding space C2. For this reason, the excessive adhesive M does not proceed further to the bearing inner side (sleeve member 8 side). In this embodiment, since the holding space C2 is a tapered space (see FIG. 5), the adhesive M is drawn toward the bonding gap C4 by the capillary force downward of the tapered space. As a result, the adhesive M is reliably prevented from overflowing to the sleeve member 8 side, and further, the adhesive M is provided between the contact surface 12a of the lid member 10 that contacts each other and the lower end surface 8c of the sleeve member 8. It is possible to accurately position the lid member 10 in the axial direction while avoiding the situation of the intrusion.

  In this embodiment, a dynamic pressure groove 8c1 is formed in the lower end surface 8c, and the contact surface 12a contacts the mountain region 8c2 (see FIG. 3B) between the adjacent dynamic pressure grooves 8c1. Even in such a case, the adhesive M is held in the gap between the contact surface 12a and the bottom surface 8c11 of the dynamic pressure groove 8c1 by holding the excess portion of the adhesive M in the holding space C2 or pulling it to the bonding gap C4 side. Can be prevented from entering.

  Further, in this embodiment, by securing the press-fitting region C3 below the adhesive reservoir C1, the coaxiality between the lid member 10 and the housing 7 is secured, and above the press-fitting region C3 (inside the bearing). A further sealing effect can be obtained by providing the adhesive reservoir C1 in the. Further, the adhesive M accumulated in the adhesive reservoir C1 engages with the lid member 10 in the axial direction and acts as a retaining member for the lid member 10, so that the fixing force between the housing 7 and the lid member 10 is increased. It can be further increased.

  After the lid member 10 is bonded and fixed to the housing 7 as described above, the fluid pressure bearing device 1 is completed by filling the internal space of the housing 7 with lubricating oil. At this time, the oil surface of the lubricating oil filled in the internal space of the housing 7 sealed by the seal portion 9 is formed on the inner periphery of the seal portion 9, and a tapered surface 9b that gradually increases in diameter toward the upper side, and a shaft member 2 is maintained in a seal space S formed between the outer peripheral surface 2a1 of the two shaft portions 2a.

  In the dynamic pressure bearing device 1 configured as described above, when the shaft member 2 is rotated, formation regions (upper and lower two places) of the dynamic pressure grooves 8a1 and 8a2 on the inner peripheral surface 8a of the sleeve member 8, and these dynamic pressure grooves Pressure due to the dynamic pressure action of the lubricating oil is generated in the radial bearing gap between the outer peripheral surface 2a1 of the shaft portion 2a facing the formation area of 8a1 and 8a2, and the shaft portion 2a of the shaft member 2 rotates in the radial direction. It is supported non-contact freely. Thus, the first radial bearing portion R1 and the second radial bearing portion R2 that support the shaft member 2 in a non-contact manner so as to be rotatable in the radial direction are formed (see FIG. 2). Further, between the formation region of the dynamic pressure groove 8c1 formed in the lower end surface 8c of the sleeve member 8 and the upper end surface (thrust receiving surface) 2b1 of the flange portion 2b facing the formation region of the dynamic pressure groove 8c1. Thrust bearing gap and a thrust bearing gap between the formation region of the dynamic pressure groove formed on the thrust receiving surface 11a of the lid member 10 and the lower end surface (thrust receiving surface) 2b2 of the flange portion 2b facing this region. In addition, pressure due to the dynamic pressure action of the lubricating oil is generated, and the flange portion 2b of the shaft member 2 is supported in a noncontact 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 shaft member 2 in a non-contact manner so as to be rotatable in the thrust direction are formed.

  Thus, when the shaft member 2 is rotated in a state where the housing 7 is filled with the lubricating oil, as shown in FIG. 5, the space between the lower end surface 8c of the sleeve member 8 and the upper end surface 2b1 of the flange portion 2b. Thrust bearing gaps are formed between the lower end surface 2b2 of the flange portion 2b and the thrust receiving surface 11a of the lid member 10, respectively. At this time, the sum total of both thrust bearing gaps is equal to the axial step between the thrust receiving surface 11a and the contact surface 12a of the lid member 10 minus the axial width of the flange portion 2b. That is, by setting the axial width of the flange portion 2b and the axial step between the thrust receiving surface 11a and the contact surface 12a with high accuracy, the lid member 10 is simply pushed forward until it contacts the sleeve member 8 during assembly. Thus, the total sum of both thrust bearing gaps is properly managed.

  Further, as described above, the dynamic pressure groove 8a1 of the first radial bearing portion R1 is formed to be axially asymmetric (X1> X2) with respect to the axial center m (see FIG. 3A). 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 sleeve member 8 and the outer peripheral surface 2a1 of the shaft portion 2a flows downward, and the first thrust bearing portion T1 It circulates through the path of thrust bearing clearance → dynamic pressure groove 8c1 → axial groove 8b1 → circumferential groove 8d1 → radial groove 8d2, and between the inner peripheral surface 8a of the sleeve member 8 and the outer peripheral surface 2a1 of the shaft portion 2a. Returning to the gap, it is again drawn into the radial bearing gap of the first radial bearing portion R1. Thus, the pressure balance inside the bearing is adjusted by configuring the lubricating oil to flow and circulate in the internal space of the housing 7. Also, an undesirable flow of the lubricating oil in the bearing internal space, for example, a phenomenon in which the pressure of the lubricating oil becomes a negative pressure locally is prevented, and bubbles are generated due to the generation of the negative pressure. Problems such as leakage and vibration can be solved. Further, when the lid member 10 is fixed, the adhesive M that is about to overflow to the sleeve member 8 side is held by the holding space C2, thereby preventing the adhesive M from blocking the dynamic pressure groove 8c1 and the axial groove 8b1. Thus, the smooth flow of the lubricating oil flowing through the circulation path can be prevented from being hindered.

  Although one embodiment of the present invention has been described above, the present invention is not limited to this embodiment.

  In the above embodiment, the case where the lid member 10 is press-fitted and bonded to the lower end of the housing 7 has been described. If this is done, press-fitting is not necessary. For example, after positioning with the lid member 10 loosely fitted to the housing 7, the adhesive M is supplied from the outside of the bearing to the gap between the outer peripheral surface 10 a of the lid member 10 and the inner peripheral surface 7 a of the housing 7. It is also possible to take a method.

  In this case, since the outer diameter dimension Do1 of the first outer peripheral surface 10a1 located below the lid member 10 does not need to provide the press-fitted region C3 with the inner peripheral surface 7a of the housing 7, the upper second outer peripheral surface It may be substantially the same as the outer diameter dimension Do2 of 10a2. Then, the lid member 10 is pushed forward until the contact surface 12a contacts the lower end surface 8c. At this time, for example, as shown in FIG. 6, in addition to the adhesive gap C4 adjacent to the adhesive reservoir C1 on the upper end side, the adhesive reservoir C1 and the lower end side (the first outer peripheral surface 10a1 and the inner peripheral surface 7a of the housing 7). Adjacent adhesive gaps C5 are formed. Also in this case, the adhesive M can be uniformly filled in the adhesive gaps C4 and C5 by providing the adhesive reservoir C1 and further the holding space C2. Further, when the adhesive M is excessively supplied, the excessive adhesive M can be held in the holding space C2 to avoid such an adverse effect.

  Moreover, although the above embodiment demonstrated the case where the taper-shaped space was formed between the 3rd taper surface 10c3 of the cover member 10 and the inner peripheral surface 7a of the housing 7 as the holding space C2 of an adhesive agent, In addition, any space shape can be employed. As a space capable of holding the adhesive M, for example, although not shown, the contact surface 12a and the second outer peripheral surface 10a2 are connected to each other via the R surface, and the space between the R surface and the inner peripheral surface 7a. It is also possible to form the holding space C2. Further, not only the lid member 10 side but also the inner peripheral surface 7a side of the housing 7 can be provided with a tapered surface or the like for forming the holding space C2.

  In the above embodiment, the case where the seal portion 9 is formed integrally with the housing 7 has been described. However, for example, although not shown, the seal portion 9 is separated from the housing 7. It can be formed and attached to the housing 7 later. In that case, the sleeve member 8 may first be positioned and fixed to the inner peripheral surface 7a of the housing 7, and then the separate seal portion 9 may be fixed to the housing 7, or the opposite. In order, after fixing the seal part 9 to the housing 7, the sleeve member 8 may be fixed.

  Moreover, although the above embodiment demonstrated the case where a dynamic pressure groove was formed in the internal peripheral surface 8a of the sleeve member 8, a dynamic pressure groove is formed in the outer peripheral surface 2a1 of the axial part 2a facing the internal peripheral surface 8a. You can also In this case, since the dynamic pressure groove processing on the inner periphery of the sleeve member 8 is not required, it is not necessary to configure the bearing member with a plurality of members (such as the sleeve member 8 and the housing 7), and the bearing member is a single member. Can be configured. Thereby, the reduction of the number of parts and the assembling work associated therewith can be omitted, and the cost can be reduced.

  In the above embodiment, the radial bearing portions R1 and R2 and the thrust bearing portions T1 and T2 are configured to generate the dynamic pressure action of the lubricating fluid by the herringbone shape or spiral shape dynamic pressure grooves. However, 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 facing the radial bearing gap on the inner peripheral surface 8a of the sleeve member 8 (region serving as a radial bearing surface). ing.

  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 member 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 member 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 member 8 and the shaft portion 2a rotate relative to each other, the lubricating fluid 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. The sleeve member 8 and the shaft portion 2a are supported in a non-contact manner by the dynamic pressure action of the lubricating fluid. 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 member 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 member 8 and the shaft portion 2a rotate relative to each other in a predetermined direction, the lubricating fluid in the radial bearing gap is pushed into the minimum gap side reduced in a wedge shape, and the pressure rises. The sleeve member 8 and the shaft portion 2a are supported in a non-contact manner by the dynamic pressure action of the lubricating fluid.

  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. 8, the predetermined regions θ on the minimum gap side of the three arcuate surfaces 8a7, 8a8, and 8a9 are concentric with the axial center O of the sleeve member 8 (shaft portion 2a) as the center of curvature. And it is comprised by the circular arc of the same diameter. 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. May be. In addition, when the radial bearing portion is configured by a step bearing or a multi-arc bearing, the radial bearing portions R1 and R2 are provided with two radial bearing portions spaced apart 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.

  Moreover, in the above embodiment, the inside of the hydrodynamic bearing device 1 is filled, and the radial bearing gap between the sleeve member 8 and the shaft member 2 and the thrust between the sleeve member 8 and the housing 7 and the shaft member 2 are filled. Lubricating oil has been exemplified as a fluid that causes a dynamic pressure action in the bearing gap, but other fluids that can cause a dynamic pressure action in each bearing gap, for example, a fluid such as a gas such as air or a fluid such as a magnetic fluid. An agent or lubricating grease can also be used.

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 of a hydrodynamic bearing apparatus. (A) is sectional drawing of a sleeve member, (b) is a bottom end view of a sleeve member. It is front sectional drawing of the cover member fixed to the end of a housing. It is an expanded sectional view around the adhesion gap between the lid member and the housing. It is an expanded sectional view of the adhesive gap periphery when different fixing methods are used. It is sectional drawing which shows the other structural example of a radial bearing part. It is sectional drawing which shows the other structural example of a radial bearing part. It is sectional drawing which shows the other structural example of a radial bearing part. It is sectional drawing which shows the other structural example of a radial bearing part.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Dynamic pressure bearing apparatus 2 Shaft member 3 Disc hub 4 Stator coil 5 Rotor magnet 7 Housing 8 Sleeve member 8a1, 8a2 Dynamic pressure groove 8b1 Axial groove 8c1 Dynamic pressure groove 8d1 Circumferential groove 8d2 Radial groove 9 Sealing part 10 Cover member 10a1 First outer peripheral surface 10a2 Second outer peripheral surface 10b Recessed portion 10c1, 10c2, 10c3 Tapered surface 11a Thrust receiving surface 12a Contact surface C1 Adhesive reservoir C2 Holding space C3 Press-fitted region C4, C5 Adhesive gap R1, R2 Radial bearing portion T1, T2 thrust bearing

Claims (8)

A bearing member, a shaft member inserted in the inner periphery of the bearing member and rotating relative to the bearing member, and a dynamic pressure action of a fluid generated in a thrust bearing gap generate pressure so that the shaft member does not contact in the thrust direction. In a hydrodynamic bearing device comprising a thrust bearing portion to be supported and a lid member having a thrust bearing surface that is bonded and fixed to one end of the bearing member and forms a thrust bearing gap between the end surface of the shaft member,
The lid member has an axial step between the thrust receiving surface and an abutting surface that abuts the bearing member in the axial direction. The lid member is bonded to the bearing member facing the lid member. A fluid dynamic bearing device, wherein an adhesive reservoir is formed, and an adhesive gap having a radial gap narrower than the adhesive reservoir is formed adjacent to the adhesive reservoir.   The hydrodynamic bearing device according to claim 1, wherein the adhesive reservoir is connected to the adhesive gap through a tapered space.   The hydrodynamic bearing device according to claim 1, wherein a holding space for holding the adhesive is formed in an opening of the bonding gap.   The hydrodynamic bearing device according to claim 3, wherein the holding space reduces the radial dimension as it goes toward the bonding gap.   The hydrodynamic bearing device according to claim 1, wherein an adhesive gap is formed on one axial end side of the adhesive reservoir, and a press-fitting portion of the lid member and the bearing member is provided on the other axial end side.   The hydrodynamic bearing device according to claim 1, wherein the adhesive gap is formed at both axial ends of the adhesive reservoir.   The hydrodynamic bearing device according to claim 1, wherein the bearing member includes a sleeve member that faces the radial bearing gap and a housing that fixes the sleeve member to the inner periphery.   A motor comprising the hydrodynamic bearing device according to any one of claims 1 to 7, a rotor magnet, and a stator coil.

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