JP5284172B2 - Hydrodynamic bearing device and manufacturing method thereof - Google Patents

Description

  The present invention relates to a hydrodynamic bearing device and a manufacturing method thereof.

  The hydrodynamic bearing device supports a shaft member rotatably with an oil film formed in a 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, spindle motors for magnetic disk devices such as HDD, optical disk devices such as CD-ROM, CD-R / RW, DVD-ROM / RAM, etc., polygon scanner motors for laser beam printers (LBP), PCs It is suitably used as a motor bearing device such as a fan motor.

  For example, Japanese Patent Application Laid-Open No. 2003-336636 (Patent Document 1) includes a bearing member which is composed of a housing and a bearing sleeve fixed to the inner periphery thereof, and is open at both ends, and is inserted into the inner periphery of the bearing member. An oil film of lubricating oil formed in the radial bearing gap, including a shaft member that forms a radial bearing gap between the inner peripheral surface of the (bearing sleeve) and a seal member that is disposed at one end opening of the bearing member The hydrodynamic bearing device for supporting the shaft member in the radial direction is disclosed. In the hydrodynamic bearing device having such a configuration, the seal member forms a seal gap in which one end is opened to the atmosphere and the other end communicates with the radial bearing gap between the seal member and the outer peripheral surface of the shaft member. The seal gap keeps the oil level (gas-liquid interface) of the lubricating oil within its axial range, thereby preventing the lubricating oil leakage as much as possible.

  By the way, since the spindle motor mounted on the disk device particularly dislikes contamination with lubricating oil, in the hydrodynamic bearing device incorporated in this type of motor, the end surface of the seal member adjacent to the seal gap and the outer peripheral surface of the shaft member For example, a film having oil repellency (oil repellent film) is usually formed. If an oil repellent film is formed, for example, even when the lubricating oil retained in the seal gap is scattered to the atmosphere opening side by applying an impact load to the hydrodynamic bearing device, the scattered lubricating oil is Is returned to the seal gap. Therefore, the lubricating oil leakage can be prevented more reliably.

JP 2003-336636 A

  However, when the oil repellent film is formed, the oil repellent agent is applied to a predetermined surface with high accuracy and a drying time after the application is also required, so that the formation cost tends to increase as a whole. In particular, the end face of the seal member is often pressed by a jig used when assembling the hydrodynamic bearing device. Therefore, if an oil repellent film is formed on this surface in advance, the end face of the seal member is repelled when the hydrodynamic bearing device is assembled. The oil film may be damaged or peeled off. Such a situation not only causes a decrease in oil repellency, but also causes the oil repellant film (oil repellant) that has been peeled off into the lubricating oil to become contaminated, thereby contributing to a decrease in bearing performance. Therefore, the formation of the oil repellent film on this surface is often performed after the assembly of the members is completed. However, in order to form the oil-repellent film with high accuracy in this state, special consideration is required, and thus an increase in manufacturing cost is inevitable.

  In particular, since the end face of the seal member is exposed to the outside, the characteristics of the oil repellent film formed on this face are likely to change over time, peel off, or be damaged. Therefore, it is difficult to ensure stable oil repellency over a long period of time.

  The subject of this invention is providing the low-cost hydrodynamic bearing apparatus which can prevent lubricating oil leakage over a long period of time.

In order to solve the above-mentioned problems, in the present invention, a bearing member having at least one end opened, a shaft member that is inserted into the inner circumference of the bearing member and forms a radial bearing gap between the inner circumference surface of the bearing member, and a bearing A seal portion disposed at the opening of the member and forming a seal gap with one end opened to the atmosphere between the shaft member and the outer peripheral surface of the shaft member, and the shaft member is made of an oil film of lubricating oil formed in the radial bearing gap. In a hydrodynamic bearing device that supports in the radial direction, an oil retaining part that retains the oil surface of the lubricating oil on the inner periphery, and a lid part that reduces the clearance width of the seal gap on the air release side of the oil retaining part And the lid portion are formed by partially deforming the seal portion . A hydrodynamic bearing device is provided.

  As described above, if a cover portion for reducing the gap width of the seal gap is provided on the air release side of the oil retaining portion that holds the oil surface of the lubricating oil, the oil retaining force is applied by applying an impact load to the hydrodynamic bearing device, for example. Even when the lubricating oil held in the part is scattered, the scattered lubricating oil can be blocked by the lid part. Further, since the lid portion having such a function is provided integrally with the oil retaining portion, the labor required for providing this can be reduced compared to the case of forming an oil repellent film having the same function. . In addition, if the lid part is provided integrally with the oil retaining part, it is possible to effectively reduce the possibility that the lid part may cause contamination, and further, leakage of lubricating oil due to characteristic changes, etc. A situation where the prevention function is reduced can also be effectively avoided.

  For example, it is possible to separate the lid part and the oil retaining part and fix the lid part to the oil retaining part by an appropriate means, but if the lid part is not accurately fixed to the oil retaining part, It becomes difficult to obtain the effect reliably. Therefore, the attachment cost of the lid portion is increased, and there is a possibility that the manufacturing cost is increased. In particular, when the lid and the oil retaining part are formed of different materials, the lid is fixed to the oil retaining part due to the difference in linear expansion coefficient between them when the ambient temperature rises, such as during bearing operation. There is a possibility that the aspect is adversely affected. In this respect, if the lid portion and the oil retaining portion are provided integrally, it is not necessary to consider these problems.

  The lid portion can be formed by partially deforming the seal portion. That is, the hydrodynamic bearing device configured as described above is a lid that reduces the gap width of the seal gap to the atmosphere opening side of the oil retaining portion that holds the oil surface of the lubricating oil on the inner periphery by partially deforming the seal portion. It can manufacture through the process of forming a part. In this case, after the lid portion is formed in the above mode, the lubricating oil may be supplied to the inside of the bearing, or after the lubricating oil is supplied inside the bearing, the lid portion may be formed in the above mode. good. Especially in the latter procedure, the refueling operation can be performed easily.

  In order to reliably prevent lubricating oil leakage by providing the above-described lid portion, the gap width of the minimum width portion of the seal gap formed by the lid portion is set to the maximum width portion of the seal gap formed by the oil retaining portion. It is desirable to set it to 1/2 or less of the gap width (for example, the gap width of the seal gap formed at the boundary portion between the oil retaining portion and the lid portion, see FIG. 6).

  If a concave portion is provided in the shaft member and the tip of the lid portion is accommodated in the concave portion, the atmosphere opening portion of the seal gap can have a labyrinth structure. Therefore, it becomes possible to prevent the lubricating oil leakage more effectively.

  In the above configuration, the inner peripheral surface of the oil retaining portion can be a straight surface extending along the axis, and can be gradually reduced in diameter toward the anti-atmosphere release side (bearing inner side). If the latter configuration is adopted, the seal gap formed on the inner peripheral surface of the oil retaining portion has a wedge shape in which the gap width is gradually reduced toward the bearing inner side, and is held on the inner periphery of the oil retaining portion. Lubricating oil can be drawn into the inside of the bearing by capillary force. Therefore, it is suitable for preventing external leakage of the lubricating oil. Further, as will be described later, when the seal portion is molded with a resin material or the like, since the draft angle is secured by the gradually reduced inner peripheral surface, the inner peripheral surface accuracy of the oil retaining portion can be improved. . There is no limitation in the diameter reduction aspect of the internal peripheral surface of an oil retaining part, and it may be linear or curvilinear.

  The bearing member may include a bearing sleeve having a surface that defines an outer diameter dimension of the radial bearing gap, and a housing in which the bearing sleeve is accommodated in the inner periphery. In this case, the seal portion may be a bearing sleeve. Can be molded integrally with the housing as an insert part. If it does in this way, the number of parts and the assembly man-hour of each part can be reduced, and cost reduction of a hydrodynamic bearing device can be attained.

  At this time, if the bearing sleeve is formed of a porous body, the coupling strength between the bearing sleeve and the housing can be increased by the anchor effect. Further, during the operation of the bearing, abundant lubricating oil can always be interposed in the radial bearing gap by the seepage of the lubricating oil held in the internal pores of the bearing sleeve. Accordingly, the possibility of oil film breakage is reduced, and the desired bearing performance can be stably maintained. However, in this case, it is necessary to ensure a large volume of the seal gap as the amount of lubricating oil to be filled in the internal space of the bearing device is increased as compared with the case where the entire bearing member is formed of a non-porous body. This means that the amount of lubricating oil to be held in the seal gap increases, and accordingly, the possibility of lubricating oil leakage increases, but this is the case if the configuration of the present invention is adopted. Also, it is possible to effectively prevent lubricating oil leakage.

  The seal portion may be molded integrally with the bearing member. In addition, the "bearing member" said here intends what provided said bearing sleeve and the housing integrally (refer FIG. 13). In this way, it is possible to further reduce the cost of the hydrodynamic bearing device by further reducing the number of members and the number of assembly steps.

  As described above, when the seal portion is molded integrally with the housing or the bearing member, a metal material can be used as the molding material for the seal portion in addition to the resin material. As the resin material, a material having a thermoplastic resin as a base resin can be used, and as the metal material, a low melting point metal such as a magnesium alloy can be used. In addition to these, the seal portion can be molded by so-called MIM molding.

  The present invention is not limited to the hydrodynamic bearing device in which the seal portion is molded integrally with the housing or the bearing member as described above, but also a hydrodynamic bearing device in which the seal portion is a separate member (for example, the above-mentioned patent document). 1 can also be suitably employed.

  The bearing member may have a substantially cylindrical shape with the other end opened. In this case, the other end opening of the bearing member can be closed with a lid member fixed to the other end opening of the bearing member, but in order to stably maintain the desired bearing performance, Fixed strength becomes a problem. This is because when an impact load is applied during operation of the hydrodynamic bearing device, the end of the shaft member hits the lid member, and the lid member may fall off due to the impact at this time. When the lid member is fixed to the inner peripheral surface of the bearing member as in the hydrodynamic bearing device of the above-mentioned Patent Document 1, if the thickness of the lid member is increased, the fixing area of the lid member with respect to the bearing member is increased, so that the lid for the bearing member is increased. The fixing strength of the member can be increased. However, when the cover member is thickened, the axial dimension of the bearing device is increased or the bearing span of the radial bearing portion is reduced. Therefore, the cover member cannot be thickened unnecessarily.

  In view of the above situation, when the other end opening of the bearing member is closed with a separate lid member, it is desirable to fix the lid member to the outer peripheral surface of the bearing member. In this way, compared to the case where the lid member is fixed to the inner peripheral surface of the bearing member as in the configuration disclosed in Patent Document 1, the fixed area of both is equal to the difference in diameter between the inner peripheral surface and the outer peripheral surface. Can be increased. In this case, the lid member requires a disk-shaped plate portion that closes the other end opening of the bearing member, and a cylindrical tube portion that is fixed to the outer peripheral surface of the bearing member (see FIG. 2). In order to increase the fixed area of the lid member with respect to the bearing member, it is sufficient to increase the axial dimension of the cylindrical portion, and it is not necessary to increase the thickness of the plate portion. Further, even if the cylindrical portion is lengthened, the overall length of the bearing device is not affected. From the above, it is possible to increase the anti-slip strength of the lid member without affecting the axial dimension of the bearing device and the bearing span of the radial bearing portion, and the desired bearing performance can be stably maintained.

  The hydrodynamic bearing device is attached and fixed to the inner periphery of the motor. With the above configuration, the lid member can be used as an attachment portion to a member that serves as a base of the motor, for example, a motor bracket. Considering the cost, it is effective to make the bearing member made of resin. However, in this case, it is difficult to secure the required fixing strength when adhesively fixing to a motor bracket that is usually made of metal. . On the other hand, if the bearing member is made of metal, the fixing strength can be satisfied, but it cannot be denied that the cost is higher than that of the resin member. On the other hand, with the above configuration, the lid member is made of a metal material having high adhesiveness to the motor bracket, and the bearing member is made of resin while satisfying the fixing strength of the hydrodynamic bearing device to the motor bracket. The demand for reduction can also be satisfied.

  As described above, according to the present invention, it is possible to provide a hydrodynamic bearing device capable of preventing leakage of lubricating oil over a long period of time at a low cost.

It is sectional drawing which shows notionally the spindle motor for disk apparatuses. It is sectional drawing which shows the hydrodynamic bearing apparatus which concerns on 1st Embodiment of this invention. It is sectional drawing of a bearing member. It is a figure which shows the lower end surface of a bearing member. It is a figure which shows the upper side end surface of the plate part of a cover member. It is a principal part expanded sectional view of the hydrodynamic bearing apparatus shown in FIG. Fig. 2 conceptually shows a process of forming a lid, in which Fig. 1 (a) shows a state immediately before the formation of the lid, and Fig. 2 (b) conceptually shows a state immediately after the formation of the lid. It is a principal part expanded sectional view of the hydrodynamic bearing apparatus shown in FIG. It is a principal part expanded sectional view which shows the formation process of the cover part based on another method notionally, (a) A figure is the state immediately before formation of a cover part, (b) A figure is the state immediately after formation of a cover part. Respectively. It is a principal part expanded sectional view which shows the other example of the oil supply method notionally, (a) A figure is the state just before oil supply, (b) A figure is the state during oil supply, (c) A figure is the state after oil supply Respectively. FIG. 5 is an enlarged cross-sectional view of a main part showing a modification of the hydrodynamic bearing device shown in FIG. It is sectional drawing which shows the hydrodynamic bearing apparatus which concerns on 2nd Embodiment of this invention. It is sectional drawing which shows the hydrodynamic bearing apparatus which concerns on 3rd Embodiment of this invention.

  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. The 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. A stator coil 4 and a rotor magnet 5 that are opposed to each other through a gap, and a motor bracket 6 as a base member are provided. The stator coil 4 is attached to the outer periphery of the motor bracket 6, and the rotor magnet 5 is attached to the inner periphery of the disk hub 3. The bearing member 7 of the hydrodynamic bearing device 1 is fixed to the inner periphery of the motor bracket 6. One or a plurality (two in the illustrated example) of disks D such as magnetic disks are held on the disk hub 3, and the disks D are fixed by a clamp mechanism (not shown). In the above configuration, 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 disk hub 3 and the disk D held by the disk hub 3 are rotated. It rotates integrally with the shaft member 2.

  FIG. 2 shows the hydrodynamic bearing device 1 according to the first embodiment of the present invention. The hydrodynamic bearing device 1 includes a substantially cylindrical bearing member 7 having both axial ends open, a shaft member 2 inserted into the inner periphery of the bearing member 7, and a lid member 10 that closes one end opening of the bearing member 7. As a constituent member, and the internal space of the bearing member 7 is filled with lubricating oil. In the following, for the sake of convenience, the description will be given with the side on which the lid member 10 is provided as the lower side and the opposite side in the axial direction as the upper side.

  The shaft member 2 includes a shaft portion 2 a inserted into the inner periphery of the bearing member 7, and a flange portion 2 b provided at one end of the shaft portion 2 a and disposed below the bearing member 7. Both the shaft portion 2a and the flange portion 2b are made of a metal material having high wear resistance, such as stainless steel. A small diameter portion 2a2 is formed at the lower end of the shaft portion 2a, and the shaft member 2 is formed by fitting and fixing this small diameter portion 2a2 to the inner periphery of the annular flange portion 2b. The method of fixing the shaft portion 2a and the flange portion 2b is arbitrary as long as a predetermined fixing strength can be secured between them, and press-fitting, adhesion, welding (particularly laser welding) and the like can be employed. As the shaft member 2, as described above, the shaft portion 2 a and the flange portion 2 b that are individually manufactured may be integrated by an appropriate means, or those that are integrally formed by forging or the like may be used.

  The bearing member 7 has a substantially cylindrical shape with both axial ends open, and is composed of a bearing sleeve 8 and a housing 9 which is molded with resin (injection molding) using the bearing sleeve 8 as an insert part. However, the housing 9 is integrally provided with a seal portion 92 that forms a seal gap S.

  The bearing sleeve 8 is formed in a cylindrical shape with a porous body, particularly a sintered metal porous body mainly composed of copper. The bearing sleeve 8 can be formed of a porous body other than the sintered metal, for example, a porous resin or ceramics, or can be formed of a non-porous body, for example, a soft metal such as brass. Both the inner peripheral surface 8a and the outer peripheral surface 8d of the bearing sleeve 8 are formed in a cylindrical surface shape having a constant diameter. Further, chamfers 8ei, 8eo, 8fi, and 8fo are formed on the inner peripheral edge and the outer peripheral edge at both ends in the axial direction of the bearing sleeve 8, respectively.

  As shown in FIG. 3, a cylindrical radial that forms a radial bearing gap on the inner peripheral surface 8 a of the bearing sleeve 8 (inner peripheral surface of the bearing member 7) with the outer peripheral surface 2 a 1 of the opposed shaft portion 2 a. Bearing surfaces A1 and A2 are spaced apart at two locations in the axial direction. These radial bearing surfaces A1 and A2 are surfaces that define the outer diameter of the radial bearing gap. Radial dynamic pressure generating portions formed by arranging a plurality of dynamic pressure grooves 8a1 and 8a2 in a herringbone shape are formed on the radial bearing surfaces A1 and A2, respectively. 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. With this configuration, when the shaft member 2 rotates, the lubricating oil interposed between the inner peripheral surface of the bearing member 7 and the outer peripheral surface 2a1 of the shaft portion 2a is pushed downward (unbalanced pumping ability). In addition, you may form a radial dynamic pressure generation | occurrence | production part in the outer peripheral surface 2a1 of the axial part 2a which opposes.

  As shown in FIG. 4, the lower end surface 8c of the bearing sleeve 8 is provided with a thrust bearing surface B that forms a first thrust bearing gap with the upper end surface 2b1 of the opposing flange portion 2b. A thrust dynamic pressure generating portion is formed on the surface B. The thrust dynamic pressure generating portion has a herringbone shape, and is configured by alternately arranging a plurality of dynamic pressure grooves 8c1 bent in a V shape and hill portions 8c2 shown by cross hatching in the drawing to divide the grooves in the circumferential direction. Is done. In addition, you may form a thrust dynamic pressure generation | occurrence | production part in the upper side end surface 2b1 of the flange part 2b which opposes.

  The housing 9 has a substantially cylindrical shape with both axial ends open, and integrally includes a main body portion 91 that holds the bearing sleeve 8 on the inner periphery and a seal portion 92 that is provided on the upper end inner diameter side of the main body portion 91. The inner peripheral surface of the main body 91 is formed in a cylindrical surface shape having a constant diameter, and the outer peripheral surface is formed in a stepped cylindrical surface shape having a lower diameter on the lower side. Therefore, the main body 91 has a form in which the thick part 91a formed relatively thick and the thin part 91b formed relatively thin are stacked in the axial direction.

  The seal portion 92 forms a seal gap S between the opposed shaft portion 2a and the outer peripheral surface 2a1 with the upper end opened to the atmosphere and the lower end communicated with the radial bearing gap. The seal portion 92 integrally includes an oil retaining portion 92a that holds the oil level of the lubricating oil on the inner periphery, and a lid portion 92b that is disposed on the atmosphere opening side (upper side) of the oil retaining portion 92a. In the seal gap S, the axial region formed by the inner peripheral surface 92a1 of the oil retaining portion 92a has a function of absorbing a volume change amount (buffer function) accompanying a temperature change of the lubricating oil that fills the internal space of the bearing member 7. Therefore, the oil level of the lubricating oil is always held within the axial direction region of the oil retaining portion 92a. The outer peripheral surface 2a1 of the shaft portion 2a is formed in a cylindrical surface shape having a constant diameter extending along the axis, while the inner peripheral surface 92a1 of the oil retaining portion 92a is formed in a tapered surface shape that gradually decreases in diameter linearly downward. It is formed. Accordingly, in the seal gap S, the axial region formed by the oil retaining portion 92a has a wedge shape in which the gap width is gradually reduced downward. In addition, the inner peripheral surface 92a1 of the oil retaining portion 92a may be a circular arc surface that is gradually reduced in a curved shape toward the lower side.

  As shown in FIG. 6 in an enlarged manner, the lid portion 92b protrudes to the inner diameter side from the upper end portion of the oil retaining portion 92a. Accordingly, the lid portion 92b has a gap width of the seal gap S on the upper side of the oil retaining portion 92a. Reduced. More specifically, the lid portion 92b (the inner diameter end thereof) forms the minimum width portion of the seal gap S, and the gap width d2 of the minimum width portion of the seal gap S is the inner peripheral surface 92a1 of the oil retaining portion 92a. Is set to ½ or less of the gap width d1 of the maximum width portion (the seal gap S formed at the boundary portion between the oil retaining portion 92a and the oil retaining portion 92b). The lid portion 92b having the above configuration is formed by partially deforming the seal portion 92, and a specific method for forming the lid portion 92b will be described in detail later.

  The resin material used for molding the housing 9 is not particularly limited as long as it can be injection-molded. For example, a crystalline resin such as polyphenylene sulfide (PPS) or liquid crystal polymer (LCP), or a non-polyethylene such as polyphenylsulfone (PPSU). What used crystalline resin as base resin can be used. The resin material can be blended with various fillers such as a reinforcing material and a conductive filler as necessary. However, as will be described later, in this embodiment, the lid member 10 ensures conductivity. Therefore, the conductive filler is basically unnecessary. However, a conductive filler may be blended if it does not adversely affect the moldability of the housing 9 and there is no problem in terms of cost.

  As described above, the housing 9 is injection-molded using the bearing sleeve 8 as an insert part, so that the upper end surface 8b of the bearing sleeve 8 is covered with the seal portion 92 including the outer peripheral chamfer 8eo. The chamfer 8fo is coated with resin. Further, since the bearing sleeve 8 is formed of a sintered metal porous body, the resin forming the housing 9 enters the surface opening of the bearing sleeve 8 and exhibits an anchor effect. Therefore, the adhesion strength between the bearing sleeve 8 and the housing 9 becomes strong. With this configuration, the bearing sleeve 8 can be prevented from coming off from the housing 9. On the other hand, the inner peripheral chamfer 8ei at the upper end of the bearing sleeve 8 is not covered with resin. This is because the bearing sleeve 8 is positioned in the mold by bringing the upper end inner peripheral chamfer 8ei into contact with the mold during injection molding.

  On the outer diameter side of the upper end of the housing 9 that becomes the boundary between the main body portion 91 and the seal portion 92, the corner portion is thinned. By this wall removal, the thickness of the housing 9 is substantially uniform in the region from the main body 91 to the seal portion 92. Therefore, deformation of the inner peripheral surface of the seal portion 92 (particularly the oil retaining portion 92a) due to molding shrinkage after injection molding is suppressed, and the shape accuracy of the seal gap S is ensured.

  The lid member 10 is formed of a conductive metal material, and for example, by pressing a metal plate, a disk-shaped plate portion 10a and a cylindrical tube portion extending upward from the outer diameter end of the plate portion 10a. 10b is integrally formed. Although the details will be described later, the lid member 10 is fixed to the outer peripheral surface (small-diameter outer peripheral surface) 91b1 of the thin wall portion 91b constituting the housing 9 with a gap, thereby closing the lower opening of the bearing member 7. The inner peripheral surface 10b2 of the cylindrical portion 10b overlaps with a part or all of the radial bearing surface A2 (lower radial dynamic pressure generating portion) provided on the inner peripheral surface 8a of the bearing sleeve 8 in the axial direction. .

  A thrust bearing surface C is provided on the upper end surface 10a1 of the plate portion 10a (inner bottom surface of the lid member 10) to form a second thrust bearing gap with the lower end surface 2b2 of the opposing flange portion 2b. A thrust dynamic pressure generating portion is formed on the bearing surface C. The thrust dynamic pressure generating portion has a herringbone shape as shown in FIG. 5 and a plurality of dynamic pressure grooves 10a11 bent in a V-shape and a hill portion 10a12 shown by cross hatching in the drawing to divide the groove 10a11 in the circumferential direction. Are arranged alternately. The thrust dynamic pressure generating portion may be formed on the lower end surface 2b2 of the opposing flange portion 2b.

  The upper end surface 10b1 of the cylindrical portion 10b and the lower end surface (step surface) 91a1 of the thick portion 91a of the housing 9 are opposed to each other in the axial direction via a first axial gap δ1 having a predetermined width. The first axial gap δ1 has a gap width of the upper end surface 2b1 of the flange portion 2b and the lower end surface 8c of the bearing sleeve 8, and the lower end surface 2b2 of the flange portion 2b and the upper end surface of the plate portion 10a of the lid member 10. It is set to a value that allows the axial movement of the lid member 10 and the bearing member 7 until they abut against each other in the axial direction, and is formed by setting the width of a thrust bearing gap described later. The first axial gap δ1 is filled with an adhesive, whereby the first axial gap δ1 is completely sealed. Further, the lower end surface of the thin portion 91b of the housing 9 and the upper end surface 10a1 of the plate portion 10a of the lid member 10 are opposed to each other in the axial direction via a second axial gap δ2 having a predetermined width.

  The hydrodynamic bearing device 1 having the above configuration is completed, for example, according to the following procedure.

  First, the shaft member 2 is inserted into the inner periphery of the bearing member 7 obtained by injection molding the housing 9 with resin using the bearing sleeve 8 as an insert part. However, at this stage, as shown in FIG. 7A, the bearing member 7 (housing 9) is not formed with the seal portion 92 (lid portion 92b) having a predetermined shape. It does not form as. More specifically, an annular protrusion 92 b ′ protruding upward in the axial direction is injection-molded integrally with the seal portion 92 on the inner periphery of the upper end of the seal portion 92.

  After the shaft member 2 is inserted into the inner periphery of the bearing member 7, for example, an appropriate adhesive (here, an epoxy-based adhesive) is applied to the small-diameter outer peripheral surface 91b1 of the housing 9, and the lid member is applied to the small-diameter outer peripheral surface 91b1. The inner peripheral surfaces of the ten cylindrical portions 10b are fitted. The bearing member 7 and the lid member 10 are relatively moved in the axial direction as they are, the upper end surface 2b1 of the flange portion 2b is brought into contact with the lower end surface 8c of the bearing sleeve 8, and the lower end surface 2b2 of the flange portion 2b is brought into the lid member. The upper and lower end surfaces 10a1 of the ten plate portions 10a are brought into contact with each other so that the gap widths of the thrust bearing gaps are set to zero. At this time, the dimension of each member is set so that the upper end surface 10b1 of the cylindrical portion 10b of the lid member 10 and the stepped surface 91a1 of the housing 9 do not contact each other. Next, the lid member 10 is pulled back downward (in the direction away from the bearing member 7) from the bearing member 7 by the total amount of the clearance widths of both thrust bearing gaps, and the relative positioning of the lid member 10 with respect to the bearing member 7 is performed. After that, the first axial gap δ1 is filled with an adhesive. Then, baking is performed to solidify the adhesive. Thereby, the assembly of the lid member 10 to the bearing member 7 and the setting of the width of the thrust bearing gap are completed at the same time. With the assembly procedure described above, the width of the thrust bearing gap can be set by the amount of movement of the lid member 10, so that the processing accuracy of each member can be relaxed and the processing cost can be reduced.

  The interior space of the bearing member 7 is filled with lubricating oil including the internal pores of the bearing sleeve 8. As described above, before the lid portion 92b is formed, that is, before the gap width of the opening portion (atmosphere release portion) of the seal gap S is narrowed, the lubricating oil should be supplied to the internal space of the bearing member 7. Thus, the refueling operation can be performed easily.

  As described above, in the hydrodynamic bearing device 1 according to the present embodiment, the housing 9 of the bearing member 7 is made of resin, the lid member 10 is made of metal, and the cylindrical portion 10b of the lid member 10 has a bearing sleeve. 8 overlaps a part of the lower radial bearing surface A2 provided on the inner peripheral surface 8a in the axial direction. In such a case, if the lid member 10 is fixed to the housing 9 by a method involving press-fitting (press-fitting, press-fitting adhesion, etc.), the deformation of the housing 9 due to the press-fitting also reaches the radial bearing surface A2, and the radial bearing gap There is a possibility of adversely affecting the width accuracy and consequently the rotational accuracy in the radial direction. Therefore, in the present embodiment, a minute radial clearance is interposed between the inner peripheral surface of the cylindrical portion 10 of the lid member 10 and the small-diameter outer peripheral surface 91b1 of the housing 9, and both are bonded with an adhesive that satisfies this radial clearance. Adhesion is fixed (gap adhesion).

  Next, with the outer peripheral surface and outer bottom surface of the bearing member 7 positioned and held, the annular protrusion 92b ′ formed on the inner periphery of the upper end of the seal portion 92 is pressurized with the jig 20 as shown in FIG. Then, the annular protrusion 92b ′ is deformed (folded) inward in the radial direction. Thereby, as shown in FIG. 7B, a lid portion 92b for reducing the gap width of the seal gap S is formed on the upper side of the oil retaining portion 92a. Of the jig 20 used at this time, at least the contact portion with the annular protrusion 92b 'is preferably heated to the softening point of the base resin constituting the housing 9 (seal portion 92). This is because the annular protrusion 92b 'can be easily and smoothly deformed to form the lid portion 92b with high accuracy.

  In the above, the lid member 10 is bonded and fixed to the bearing member 7 (housing 9) using an epoxy adhesive. However, if a predetermined fixing strength (adhesive strength) can be secured between the two, an epoxy-based adhesive is used. It is also possible to use an adhesive other than the adhesive, such as an anaerobic adhesive or an ultraviolet curable adhesive.

  In the above description, when the lid member 10 is fixed to the bearing member 7, an adhesive is applied in advance to the small-diameter outer peripheral surface 91 b 1 of the housing 9. However, the lid member 10 and the bearing member 7 are fitted and thrusted. After setting the width of the bearing gap, an adhesive is supplied from the axial gap δ1, and the capillary force of the radial gap between the small-diameter outer peripheral surface 91b1 of the housing 9 and the inner peripheral surface of the cylindrical portion 8b is used. You may adhere and fix both by drawing in the adhesive.

  In the hydrodynamic bearing device 1 having the above-described configuration and manufactured as described above, when the shaft member 2 rotates, the radial bearing surfaces are provided separately at two locations on the upper and lower sides of the inner peripheral surface 8a of the bearing sleeve 8. A radial bearing gap is formed between each of A1 and A2 and the outer peripheral surface 2a1 of the shaft portion 2a opposed thereto. As the shaft member 2 rotates, the oil film pressure in the radial bearing gaps is increased by the dynamic pressure action of the dynamic pressure grooves 8a1 and 8a2. As a result, the radial bearing portions R1 and R2 that support the shaft member 2 in the radial direction without contact are provided. Separately formed at two positions in the axial direction. At the same time, between the thrust bearing surface B provided on the lower end surface 8c of the bearing sleeve 8 and the upper end surface 2b1 of the flange portion 2b, and the lower end surface 2b2 of the flange portion 2b and the upper end surface 10a1 of the plate portion 10a. The first and second thrust bearing gaps are respectively formed between the thrust bearing surface C and the thrust bearing surface C. As the shaft member 2 rotates, the oil film pressure in the gap between the thrust bearings is increased by the dynamic pressure action of the dynamic pressure grooves 8c1 and 10a11. As a result, the first thrust bearing portion that supports the shaft member 2 in a thrust non-contact manner. T1 and second thrust bearing portion T2 are formed.

  Further, in the seal gap S, the axial region formed by the inner peripheral surface 92a1 of the oil retaining portion 92a has a wedge shape with the radial dimension gradually reduced downward (inside the bearing member 7). Therefore, the lubricating oil held on the inner periphery of the oil retaining portion 92a is drawn toward the inner side of the bearing member 7 by the drawing action by the capillary force. Further, as described above, in the seal gap S, the axial region formed by the inner peripheral surface 92a1 of the oil retaining portion 92a absorbs the volume change amount accompanying the temperature change of the lubricating oil that fills the internal space of the bearing member 7. It has a function (buffer function), and always keeps the oil level of the lubricating oil within the range of the assumed temperature change.

  The seal portion 92 is injection-molded with resin integrally with the housing 9, but the inner peripheral surface 92a1 of the oil retaining portion 92a that holds the oil surface of the lubricating oil is formed on a tapered surface that gradually decreases in diameter downward. Therefore, this surface ensures a draft angle during injection molding. Accordingly, the accuracy of the inner peripheral surface 92a1 of the oil retaining portion 92a that retains the oil surface of the lubricating oil can be increased, and the retaining performance of the lubricating oil can be enhanced.

  In addition, in the present invention, since the lid portion 92b for reducing the gap width of the seal gap S is provided on the air release side of the oil retaining portion 92a, for example, the holding portion is applied by applying an impact load to the hydrodynamic bearing device 1. Even when the lubricating oil retained within the axial range of 92a scatters, external leakage of the scattered lubricating oil can be prevented by the lid portion 92b. In particular, as described above, the gap width d2 of the minimum width portion of the seal gap S formed by the lid portion 92b is equal to or less than ½ of the gap width d1 of the maximum width portion of the seal gap S formed by the holding portion 92a. If so, external leakage of the lubricating oil can be reliably prevented. Further, since the lid portion 92b having such a function is provided integrally with the oil retaining portion 92a, the labor required for providing this is compared with the case where an oil repellent film having the same function is formed on the end surface of the seal portion 92. Can be reduced. Moreover, if the cover part 92b is provided integrally with the oil retaining part 92a, the cover part 92b may be damaged, and the possibility of causing contamination is effectively reduced. Further, the lid portion 92b is unlikely to change in characteristics with the passage of time unlike the oil repellent film, and accordingly, the function of preventing the external leakage of the lubricating oil can be stably maintained over a long period of time.

  As described above, the hydrodynamic bearing device 1 employing the configuration of the present invention can reliably prevent external leakage of the lubricating oil while being low in cost. Particularly in this embodiment, since a part of the bearing member 7 is constituted by the bearing sleeve 8 made of a porous body, the volume of the seal gap S is increased by the amount of the lubricating oil filled in the internal space of the bearing member 7. It is necessary to ensure a large. This means that the amount of lubricating oil to be held in the seal gap S increases, and accordingly, the possibility of lubricating oil leakage increases. However, if the above-described configuration of the present invention is adopted, this is the case. Even in this case, it is possible to reliably prevent lubricating oil leakage.

  In the above, a special description is omitted, but if there is no problem in terms of cost or the like, an oil repellent film may be formed in a region facing the lid portion 92b in the outer peripheral surface 2a1 of the shaft portion 2a. . In this way, lubricating oil leakage can be prevented more reliably.

  As described above, when the shaft member 2 rotates, the lubricating oil filled in the radial bearing gap is pushed downward by the unbalance of the pumping ability of the radial dynamic pressure generating portion. In this case, the pressure increases in the space on the closed side inside the bearing, particularly the space on the inner diameter side of the second thrust bearing gap (bottom space P, see FIG. 8), and the upward levitation force acting on the shaft member 2 is excessive. As a result, it becomes difficult to balance the thrust support force between the thrust bearing portions T1, T2. In view of this point, in the present embodiment, as shown in an enlarged view in FIG. 8, the communication holes 11 are provided in the both end faces 2b1 and 2b2 of the flange portion 2b. As a result, the lubricating oil can go back and forth between the two thrust bearing gaps via the communication hole 11, so that the collapse of the pressure balance between the two thrust bearing gaps can be eliminated at an early stage, and the two thrust bearing portions T1 and T2 can be connected. The thrust support force can be balanced.

  In the illustrated example, the communication hole 11 is composed of a radial portion 11a and an axial portion 11b, and is opened to the inner diameter side of the thrust bearing surfaces B and C (thrust dynamic pressure generating portions) to avoid the formation region. Presents a bent shape. More specifically, the outer diameter end of the radial direction portion 11a is a space formed by the upper end surface 2b1 of the flange portion 2b, the lower end inner peripheral chamfer 8fi of the bearing sleeve 8, and the numi portion 2a3 provided at the lower end of the shaft portion 2a. The axial direction portion 11b connected to the inner diameter end of the radial direction portion 11a extends along the outer peripheral surface of the small diameter portion 2a2 of the shaft portion 2a and opens to the inner diameter side of the second thrust bearing portion T2. In such a configuration, an axial groove is formed on the inner peripheral surface of the annular flange portion 2b, and a radial groove communicating with the axial groove is formed on the upper end surface 2b1 of the flange portion 2b. It can be formed by fitting the small diameter portion 2a2 of the shaft portion 2a to the inner periphery. In addition, the communication hole 11 can be provided in one place in the circumferential direction, or can be provided in a plurality of places in the circumferential direction.

  Further, as described above, in the hydrodynamic bearing device 1 according to the present embodiment, the pressure in the bottom space P tends to increase, and thus the dynamic pressure groove 10a11 that forms the second thrust bearing portion T2 has been frequently used. If the pump-in type is arranged in a spiral shape, the lubricating oil filled in the second thrust bearing gap is pushed into the inner diameter side, which helps increase the pressure in the bottom space P. In order to avoid this, it is desirable to form the dynamic pressure groove 10a11 forming the second thrust bearing portion T2 in the herringbone shape shown in FIG. On the other hand, since this type of problem does not occur in the first thrust bearing portion T1, the dynamic pressure groove 8c1 may be formed in a pump-in type spiral shape instead of the herringbone shape shown in FIG.

  The hydrodynamic bearing device 1 having the above configuration includes a motor bracket 6 (see FIG. 1) in which the outer peripheral surface of the cylindrical portion 10b of the lid member 10 and the large-diameter outer peripheral surface of the housing 9 are formed of a metal material such as an aluminum alloy. ), For example, by being bonded and fixed to the inner peripheral surface. At this time, if the outer diameters of the housing 9 and the lid member 10 are made equal, they can be securely fixed to the inner peripheral surface of the motor bracket 6. And in this embodiment which made both the cover member 10 and the motor bracket 6 metal, high adhesive strength can be ensured between both. Therefore, the hydrodynamic bearing device 1 can be fixed to the motor bracket 6 with high adhesive strength. Note that the housing 9 is not necessarily bonded and fixed to the motor bracket 6 as long as sufficient adhesive strength can be secured between the lid member 10 and the motor bracket 6.

  Moreover, since the cylinder part 10b of the cover member 10 is being fixed to the outer peripheral surface (small-diameter outer peripheral surface 7a3) of the bearing member 7, when fixing a cover member to the inner peripheral surface of a bearing member (housing) like the past. In comparison, the fixed area between both members can be increased by the difference in diameter between the inner peripheral surface and the outer peripheral surface. Moreover, in order to increase the fixed area of the lid member 10 with respect to the bearing member 7, it is sufficient to increase the axial dimension of the cylindrical portion 10b, and it is not necessary to increase the thickness of the plate portion 10a of the lid member 10. Therefore, the fixing strength of the lid member 10 to the bearing member 7 can be increased without increasing the axial dimension of the hydrodynamic bearing device 1 and shortening the spans of the radial bearing portions R1 and R2.

  Further, since the lid member 10 is made of a metal material, the static electricity charged by the rotation of the disk D is surely discharged to the ground side via the path of the shaft member 2 → the lid member 10 → the motor bracket 6. be able to. However, in the present embodiment in which the lid member 10 and the motor bracket 6 are bonded and fixed, in order to prevent a situation where the conductive path is blocked by an adhesive (usually an insulator), the lower end of the lid member 10 is necessary. It is desirable to apply a suitable conductive material across the outer diameter end and the lower end inner diameter end of the bracket 6 to form a conductive coating.

  If the conductive path is constituted by the lid member 10 in this way, it is not necessary to consider the conductivity of the bearing member 7, so that there is room for material selection when examining the molding material of the housing 9. Increase design freedom. When the resin-made housing 9 is made conductive, it is usual to mix expensive conductive fillers in the resin material. However, in the present invention, this type of conductive filler is not necessary. Or, since the blending amount can be reduced, an increase in material cost can be suppressed.

  In the above, as shown in FIGS. 7A and 7B, the annular protrusion 92b ′ protruding upward in the axial direction is molded at the same time as the seal portion 92 (housing 9) is injection-molded, and this is formed on the inner diameter side. The lid portion 92b is formed by deforming (bending), but the lid portion 92b is not formed only by this procedure. For example, as shown in FIG. 9A, the upper end surface of the seal portion 92 is injection-molded with a resin on a flat surface in a direction orthogonal to the axis, and then the upper end of the seal portion 92 as shown in FIG. 9B. The lid portion 92b can also be formed by deforming the inner peripheral edge portion to the inner diameter side with the jig 20.

  Further, in the above, the lid portion 92b is formed by partially deforming the seal portion 92 after filling the internal space of the bearing member 7 with the lubricating oil, but it is also possible to take the reverse procedure. is there. Specifically, after forming the lid portion 92b as shown in FIG. 10A, the lid portion 92b is elastically deformed as shown in FIG. 10B. In the deformation region of the lid portion 92b, since the opening size of the seal gap S is enlarged, the lubricating oil is supplied by inserting the oil filler 21 into the inner periphery of the seal portion 92 from this region. When the refueling tool 21 is pulled out after the refueling operation is completed, the lid portion 92b is elastically returned in the manner shown in FIG.

  Further, the seal gap S can be configured as shown in FIG. Specifically, the recess 2a4 is provided on the outer peripheral surface 2a1 of the shaft portion 2a, and the inner periphery of the tip of the lid portion 92b constituting the seal portion 92 is accommodated in the recess 2a4. With such a configuration, the upper end portion (atmosphere release portion) of the seal gap S can have a labyrinth structure, so that it is possible to more effectively prevent lubricating oil leakage.

  As mentioned above, although one embodiment of the hydrodynamic bearing device 1 to which the configuration of the present invention was applied was described, the present invention is not limited to the hydrodynamic bearing device 1 having the above configuration, and other embodiments described below are applied. Of course, it is also possible to apply to such a hydrodynamic bearing device 1. In the following, only differences from the hydrodynamic bearing device 1 described above will be described in detail, and substantially the same members and the like will be denoted by common reference numerals and redundant description will be omitted.

  FIG. 11 shows a second embodiment of the hydrodynamic bearing device 1 according to the present invention. Like the one shown in FIG. 2, the bearing member 7 includes a bearing sleeve 8 and the bearing sleeve 8 as an insert part. The housing 9 integrally includes a seal portion 92 that is injection-molded with resin, and the metal lid member 10 is fixed to the small-diameter outer peripheral surface 91 b 1 of the housing 9. After setting the width of the thrust bearing gap, an axial gap δ1 is formed between the upper end surface 10b1 of the cylindrical portion 10b of the lid member 10 and the stepped surface 91a1 of the housing 9.

  In the hydrodynamic bearing device 1 according to the second embodiment, a covering portion 91c extending toward the inner diameter side is formed at the lower end of the thin portion 91b constituting the main body portion 91 of the housing 9, and the outer periphery of the bearing sleeve 8 is formed by the covering portion 91c. Not only the chamfer 8fo but also the entire lower end surface 8c of the bearing sleeve 8 is covered. A plurality of dynamic pressure grooves (for example, herringbone-shaped dynamic pressure grooves shown in FIG. 4) functioning as thrust dynamic pressure generating portions of the first thrust bearing portion T1 are formed on the end surface of the covering portion 91c.

  Thus, by forming the thrust dynamic pressure generating portion in the covering portion 91c of the housing 9, the thrust dynamic pressure generating portion formed on the lower end surface 8c of the bearing sleeve 8 becomes unnecessary. Therefore, the radial thickness of the bearing sleeve 8 can be reduced as compared with the embodiment shown in FIG. This thinning can reduce the oil content in the bearing sleeve 8 made of sintered metal, so that the oil retention amount of the entire bearing device can be reduced, and the thermal expansion amount of the lubricating oil at the time of temperature rise is suppressed. be able to. Accordingly, the volume of the seal gap S can be reduced, the axial dimension of the seal gap S can be reduced to downsize the entire bearing device in the axial direction, or the span of the radial bearing portions R1 and R2 can be expanded. Thus, the rotational accuracy in the radial direction can be improved.

  The thrust dynamic pressure generating portion of the covering portion 91c is molded simultaneously with the injection molding of the housing 9 by previously forming a groove mold corresponding to the thrust dynamic pressure generating portion in the mold for molding the housing 9. be able to. Thereby, the formation process of a thrust dynamic pressure generating part can be omitted and cost reduction can be achieved. Further, since the axial dimension of the seal gap S is reduced, the difference in thickness between the seal portion 92 and the main body portion 91 in the housing 9 is reduced, so that deformation at the time of molding shrinkage of the resin is less likely to occur. Therefore, in the hydrodynamic bearing device 1 of this embodiment, the meat removal formed in the upper end outer diameter portion of the housing 9 is omitted.

  FIG. 12 shows a third embodiment of the hydrodynamic bearing device 1 according to the present invention. In the embodiment shown in the figure, the bearing member 7 is the above-described one in that the bearing sleeve 8 shown in FIGS. 2 and 11 and a resin injection molding product integrally including a housing 9 accommodated in the inner periphery thereof are used. The configuration is different from that of the embodiment. More specifically, the bearing member 7 integrally includes a main body portion 71 composed of a thick portion 71a and a thin portion 71b, and a seal portion 72 provided on the upper end inner diameter side of the main body portion 71. Then, radial bearing gaps (radial bearing portions R1, R2) are formed between the inner peripheral surface 7a of the bearing member 7 (main body portion 71) and the outer peripheral surface 2a1 of the shaft member 2, and the bearing member 7 (the main body portion 71). A first thrust bearing gap (first thrust bearing portion T1) is formed between the lower end surface 7b of the thin portion 71b) and the upper end surface 2b1 of the flange portion 2b. The seal portion 72 is integrally formed with an oil retaining portion 72a that holds the oil level of the lubricating oil on the inner periphery and a lid portion 72b that reduces the clearance width of the seal clearance S above the oil retaining portion 72a. Is provided.

  If it does in this way, compared with embodiment described above, the number of parts and an assembly man-hour can be reduced, and cost reduction of the hydrodynamic bearing device 1 can be achieved. Further, since the entire bearing member 7 can be formed of a non-porous body, the volume of the seal gap S can be further reduced by reducing the amount of lubricating oil to be filled in the bearing. Accordingly, the axial dimension of the seal gap S can be reduced to further reduce the size of the entire bearing device in the axial direction, or the span of the radial bearing portions R1 and R2 can be expanded to further improve the rotational accuracy in the radial direction. Is possible.

  In the embodiment shown in FIG. 2 and FIG. 11 described above, resin is used as the molding material for the housing 9, and in the embodiment shown in FIG. 12, the resin is used as the molding material for the bearing member 7. If not, it is also possible to use a low melting point metal material such as a magnesium alloy or an aluminum alloy as these molding materials. These can also be so-called MIM molded products. However, when the housing 9 is a metal injection molded product or MIM molded product using the bearing sleeve 8 as an insert part, it is important that the injection material has a lower melting point than the bearing sleeve 8. This is to prevent the bearing sleeve 8, which is an insert part, from being thermally deformed.

  In the above description, the case where the configuration of the present invention is applied to the seal portion molded integrally with the housing 9 (FIGS. 2 and 12) or integrally formed with the bearing member 7 (FIG. 13) has been described. However, it is also possible to apply the configuration of the present invention to a seal portion provided separately from the housing 9 and the bearing member 7 and fixed to the housing or the like by an appropriate means.

  Further, in the above embodiment, the case where the radial bearing portions R1 and R2 including the dynamic pressure bearing are configured by the dynamic pressure action by the dynamic pressure groove having a herringbone shape or the like has been described. It is also possible to configure the radial bearing portion with other known hydrodynamic bearings such as a wave bearing and the like. Moreover, a radial bearing part can also be comprised with what is called a perfect-circle bearing which made both two surfaces which oppose through a radial bearing clearance | interval the cylindrical surface.

  In the above embodiment, the case where the thrust bearing portions T1 and T2 made of a dynamic pressure bearing are configured by the dynamic pressure action by the dynamic pressure groove having a herringbone shape or the like has been described. Any one or both of the thrust bearing portions T1 and T2 can be configured by other known hydrodynamic bearings. Further, the thrust bearing portion can be constituted by a so-called pivot bearing that contacts and supports one end of the shaft member 2.

DESCRIPTION OF SYMBOLS 1 Fluid dynamic bearing apparatus 2 Shaft member 2a Shaft part 6 Motor bracket 7 Bearing member 8 Bearing sleeve 9 Housing 91 Main body part 92 Sealing part 92a Oil retaining part 92b Lid part 10 Lid member 10b Cylindrical part 11 Communication hole A1, A2 Radial bearing surface B , C Thrust bearing surface S Seal gap R1, R2 Radial bearing portion T1, T2 Thrust bearing portion

Claims (11)

A shaft member that is inserted in the inner periphery of the bearing member at least at one end thereof, and that forms a radial bearing gap between the inner peripheral surface of the bearing member; and the shaft member disposed in the opening of the bearing member. A hydrodynamic bearing device that supports a shaft member in a radial direction with an oil film of a lubricating oil formed in a radial bearing gap.
The seal portion is integrally provided with an oil retaining portion that holds the oil level of the lubricating oil on the inner periphery and a lid portion that reduces the gap width of the seal gap on the air release side of the oil retaining portion. A hydrodynamic bearing device formed by partially deforming a seal portion .   The hydrodynamic bearing device according to claim 1, wherein the gap width of the minimum width portion of the seal gap formed by the lid portion is set to ½ or less of the gap width of the maximum width portion of the seal gap formed by the oil retaining portion.   The hydrodynamic bearing device according to claim 1, wherein the shaft member is provided with a recess, and the tip of the lid is accommodated in the recess.   The fluid dynamic pressure bearing device according to claim 1, wherein the inner peripheral surface of the oil retaining portion is gradually reduced in diameter toward the air release side. The bearing member includes a bearing sleeve having a surface that defines an outer diameter dimension of the radial bearing gap, and a housing in which the bearing sleeve is accommodated in the inner periphery,
The hydrodynamic bearing device according to claim 1, wherein the seal portion is molded integrally with the housing using a bearing sleeve as an insert part. The hydrodynamic bearing device according to claim 5 , wherein the bearing sleeve is formed of a porous body.   The hydrodynamic bearing device according to claim 1, wherein the seal portion is molded integrally with the bearing member.   2. The hydrodynamic bearing device according to claim 1, wherein the other end of the bearing member is opened, and the other end opening is closed with a lid member fixed to the outer peripheral surface of the bearing member. A shaft member that is inserted in the inner periphery of the bearing member at least at one end thereof, and that forms a radial bearing gap between the inner peripheral surface of the bearing member; and the shaft member disposed in the opening of the bearing member. And a seal portion that forms a seal gap with one end opened to the atmosphere between the outer peripheral surface of the shaft and the hydrodynamic bearing device that supports the shaft member in the radial direction with a lubricating oil film formed in the radial bearing gap In
Including a step of forming a lid portion for reducing the gap width of the seal gap on the air release side of the oil retaining portion that holds the oil surface of the lubricating oil on the inner periphery by partially deforming the seal portion. A method for manufacturing a hydrodynamic bearing device. The method for manufacturing a hydrodynamic bearing device according to claim 9 , wherein after the lid portion is formed, lubricating oil is supplied to the internal space of the bearing member. The method for manufacturing a hydrodynamic bearing device according to claim 9 , wherein the lid portion is formed after the lubricating oil is supplied to the internal space of the bearing member.

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