JP2010249218A - Fluid bearing device and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily and accurately form an axial clearance to be arranged in a fluid bearing device. <P>SOLUTION: A flange part 2b as an engaging part K arranged in a shaft member 2, is arranged on the inner diameter side of a cylinder part 10b for constituting a cover member 10. In a stopping state, a second axial clearance δ2 as the axial clearance is arranged between an upper side end surface 2b1 of the flange part 2b and a lower side end surface 7a5 of a bearing member 7. A first axial clearance δ1 is arranged between an upper side end surface 10b1 of the cylinder part 10b and a step height surface 7a4 of the bearing member 7. A relative position in the axial direction of the cover member 10 to the bearing member 7 is set constant, that is, a clearance width of the second axial clearance δ2 is set constant, by adjusting a clearance width of this first axial clearance δ1. <P>COPYRIGHT: (C)2011,JPO&INPIT

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.

  As an example of the hydrodynamic bearing device for the spindle motor among the above motors, one disclosed in Japanese Patent Laid-Open No. 2006-226250 (Patent Document 1) is known. The hydrodynamic bearing device described in Patent Document 1 includes a bearing member that is open at both ends, a shaft member that is inserted into the inner periphery of the bearing member, and a lid member that is fitted to the bearing member and closes one end opening of the bearing member. As main constituent members. In this hydrodynamic bearing device, a thrust bearing portion comprising a dynamic pressure bearing that supports a shaft member in one thrust direction is formed on one end surface of the bearing member, and a dynamic pressure that supports the shaft member in the other thrust direction on one end surface of the lid member. A thrust bearing portion comprising a bearing is formed.

  The shaft member of this type of hydrodynamic bearing device is provided with a disk hub for holding the disk. If the amount of axial movement of the shaft member relative to the bearing member increases, the head of the disk device and the disk held by the disk hub interfere with each other, and in the worst case, the disk device may not function. Therefore, regardless of whether the thrust bearing portion is composed of a dynamic pressure bearing or a pivot bearing, an engaging portion (a flange portion in Patent Document 1) that engages with the bearing member in the axial direction is provided on the shaft member. It is customary to restrict the axial movement of the member. However, if the engaging portion and the bearing member are in sliding contact, the shaft member may not be able to rotate smoothly. For this reason, an axial gap (axial gap) having a predetermined width is provided between the engaging portion and the bearing member.

  For example, when two thrust bearing parts are constituted by a dynamic pressure bearing as described in Patent Document 1, the gap width of the axial gap is a value obtained by adding the gap widths of the thrust bearing gaps of both thrust bearing parts. The In order to easily set the width of the axial gap, in the hydrodynamic bearing device of Patent Document 1, a cylindrical portion extending in the axial direction is provided on the lid member, and a flange portion as an engaging portion is disposed on the inner periphery of the cylindrical portion. In addition, the axial dimension of the cylindrical portion is set to a value obtained by adding the thickness of the flange portion and the gap width of both thrust bearing gaps. In this way, the width setting of the axial gap (thrust bearing gap) can be completed only by fitting the lid member to the bearing member so that the end faces of the cylindrical portion and the bearing member are brought into contact with each other.

JP 2006-226250 A

  However, since each member is provided with a dimensional tolerance, each member is not necessarily manufactured to the same size. Therefore, for example, when a lid member in which the axial dimension of the cylinder portion is formed at the upper limit value of the dimensional tolerance and a member having the flange portion formed at the lower limit value of the dimensional tolerance are combined, the thrust bearing gap There is a risk that the bearing width of the thrust bearing portion will be reduced. On the other hand, if the gap width of the thrust bearing gap is small, the torque may increase. For example, if the members are matched so that the gap width of the axial gap is optimum, the above problem can be solved, but the manufacturing process becomes complicated and the problem of cost increase arises.

  An object of the present invention is to make it possible to easily and accurately set the width of the axial gap in this type of hydrodynamic bearing device, thereby further improving the rotational accuracy.

  In order to achieve the above object, in the present invention, a bearing member having both ends opened, a shaft member having an engagement portion inserted in the inner periphery of the bearing member and engaged in the axial direction with the bearing member, A radial bearing that supports the shaft member in the radial direction with an oil film formed in a radial bearing gap formed between the inner peripheral surface and the outer peripheral surface of the shaft member, and one end opening of the bearing member that is fitted to the bearing member And a lid member that forms a thrust bearing portion that supports the shaft member in the thrust direction. The lid member has a cylindrical portion that extends in the axial direction, and an engaging portion is disposed on the inner diameter side of the cylindrical portion. In the fluid dynamic bearing device, there is provided a fluid dynamic bearing device characterized in that an axial gap is interposed between the bearing member and the cylindrical portion of the lid member so that the axial relative position of the lid member with respect to the bearing member is constant.

  In this way, if the axial gap is interposed between the bearing member and the cylindrical portion of the lid member, variations in the dimensions of the members that determine the gap width of the axial gap can be absorbed by the axial gap. . Specifically, the gap width of the axial gap is defined as the bearing member, the engaging portion, and one end of the shaft member on the bearing closing side (as shown in FIG. 2, the flange portion as the engaging portion is the bearing blocking of the shaft member). If it is provided at one end of the side, the bearing member and the lid member are allowed to approach each other in the axial direction until the other end of the engaging portion and the lid member abut each other in the axial direction. good. Since the axial relative position of the lid member with respect to the bearing member is made constant by interposing such an axial gap, the engaging portion of the shaft member and the bearing member An axial gap having a predetermined width can be provided between the two.

  In the case where the thrust bearing portion is formed by the lid member as in the fluid dynamic bearing device according to the present invention, in order to ensure the desired bearing performance, the perpendicularity of the outer bottom surface of the lid member to the outer peripheral surface of the bearing member (JIS B It is desirable to set 0621) to 10 μm or less.

  Further, if the configuration of the present invention described above is adopted, the tolerance of the axial relative position of the lid member with respect to the bearing member, in other words, the error of the gap width of the axial gap is set to ± 5 μm (−5 μm or more, +5 μm or less). Even if it is a case, both can be reliably fixed within this precision.

  By the way, since the number of disks mounted on the shaft member has increased with the recent increase in capacity of the disk device, it is applied to the lid member from the end of the shaft member when an impact load is applied during bearing operation or the like. The impact load also tends to increase. Therefore, in order to stably maintain the bearing performance, particularly the bearing performance of the thrust bearing portion, it is necessary to increase the slip-proof strength of the lid member. When the cylindrical portion of the lid member is fitted and fixed to the inner peripheral surface of the bearing member as described in Patent Document 1, if the axial dimension of the cylindrical portion is increased, the fixing area of the lid member with respect to the bearing member increases. Accordingly, the fixing strength of the lid member with respect to the bearing member can be increased. However, when the axial dimension of the cylindrical portion is increased, the shape of the bearing member may be complicated and the manufacturing cost of the bearing member may increase. Further, when the cylindrical portion is fitted to the inner peripheral surface of the bearing member, the cylindrical portion of the lid member and the bearing member are continuously arranged on the outer diameter side of the engaging portion (flange portion). The diameter is reduced. For this reason, particularly when a thrust bearing portion made of a dynamic pressure bearing is formed on the end face of the engaging portion, the support area may be reduced, and the support capability in the thrust direction may be reduced.

  In view of the above situation, it is desirable to fit the cylindrical portion of the lid member to the outer peripheral surface of the bearing member. In this way, the fixed area can be increased by the difference in diameter between the inner peripheral surface and the outer peripheral surface, compared with the case where the cylindrical portion of the lid member is fixed to the inner peripheral surface of the bearing member, and the fixed area with respect to the bearing member is increased. In order to enlarge the length, it is sufficient to increase the axial dimension of the cylindrical portion, and the shape of the bearing member is not particularly complicated. Moreover, since it can be set as the structure which has arrange | positioned only the cylinder part of a cover member in the outer diameter side of an engaging part, an engaging part can be enlarged in diameter. Therefore, when a thrust bearing part is comprised with a dynamic pressure bearing, a support area can be expanded and the support capability of a thrust direction can be improved.

  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.

  Thus, when fitting a cover member to the outer peripheral surface of a bearing member, examination is required for the fixing method of both. For example, if a lid member is fixed to the outer peripheral surface of the bearing member with a large press-fitting allowance, the deformation of the outer peripheral surface of the bearing member due to press-fitting also occurs on the surface that defines the outer diameter dimension of the radial bearing gap of the bearing member (radial bearing surface) And there exists a possibility of reducing the bearing performance of a radial bearing part. This problem is particularly noticeable when the cylindrical portion of the lid member and a part or all of the radial bearing surface are overlapped in the axial direction (see, for example, FIG. 2).

  Therefore, when the lid member is fitted to the outer peripheral surface of the bearing member, the lid member is fitted to the outer peripheral surface of the bearing member with a tightening margin that does not affect the surface accuracy of the radial bearing surface, and the lid member and the bearing member are It is desirable to bond and fix. If it does in this way, it will become possible to block | close the one end opening part of a bearing member reliably, avoiding the fall of the bearing performance of a radial bearing part. The lid member and the bearing member can be bonded and fixed by interposing an adhesive between the inner peripheral surface of the cylindrical portion of the lid member and the outer peripheral surface of the bearing member. The “tightening allowance that does not affect the surface accuracy” includes both a light press-fit state having a positive fastening allowance, a state where the fastening allowance is 0, and a gap fitting state in which the fastening allowance is negative. . “Gap fitting” refers to a state in which there is always a gap (JIS B 0401) even when dimensional tolerance is assumed.

  A thrust bearing gap of the first thrust bearing portion is formed between one end surface of the engaging portion and the end surface of the bearing member facing the engaging portion, and the other end surface of the engaging portion and the end surface of the lid member facing the first thrust bearing portion. A thrust bearing gap of the second thrust bearing portion can be formed therebetween. Thereby, a shaft member can be supported by a dynamic pressure bearing excellent in rotational accuracy in both thrust directions. At this time, if the gap width of the thrust bearing gap of the first thrust bearing portion and the gap width of the thrust bearing gap of the second thrust bearing portion are set to substantially the same width, the first thrust bearing portion and the second thrust bearing portion. As a result, the rotational accuracy in the thrust direction can be stabilized.

  The hydrodynamic bearing device having the above-described configuration is configured such that, for example, the bearing member and the engaging portion, and the bearing member closing side end of the shaft member and the lid member are pivoted while the outer bottom surface of the lid member is supported by a jig placed on the base. It can be manufactured through a process of removing the jig in a state in which the axial movement of the bearing member is restricted after the contact with each other in the direction (in other words, after the gap width of the axial gap is made zero). In this case, if the thickness of the jig is the same as the gap width of the axial gap to be formed, the lid member is moved away from the bearing member by the gap width of the axial gap by removing the jig. be able to. The jig is removed in a state where the axial movement of the bearing member is restricted, and the lid member does not move further in the axial direction when it comes into contact with the base. Therefore, the axial movement amount of the lid member relative to the bearing member can be managed with high accuracy. If the lid member is completely fixed to the bearing member after the axial relative movement of the lid member with respect to the bearing member is completed, the gap width of the axial gap can be set to a specified value.

  Alternatively, after the bearing member and the engaging portion, and the bearing closing side end of the shaft member and the lid member are in contact with each other in the axial direction with the outer bottom surface of the lid member supported by a jig, The jig can be manufactured through a step of moving a predetermined amount in a direction away from the bearing member in a state where the axial movement is restricted. In this case, if the movable amount of the jig is the same as the gap width of the axial gap to be formed, the lid member is separated from the bearing member by the gap width of the axial gap as the jig moves in the axial direction. Can be moved in the direction. The axial movement of the jig is performed in a state where the axial movement of the bearing member is restricted, and the lid member does not move further in the axial direction when the axial movement of the jig is completed. Therefore, the axial movement amount of the lid member relative to the bearing member can be managed with high accuracy. If the lid member is completely fixed to the bearing member after the axial relative movement of the lid member with respect to the bearing member is completed, the gap width of the axial gap can be set to a specified value.

  The movement of the jig in the separation direction can also be performed in a state where the lid member is attracted to the jig. In this way, the lid member can be reliably moved in the axial direction by the amount of movement of the jig in the axial direction, so that the amount of axial movement of the lid member relative to the bearing member can be managed with higher accuracy.

  In this type of hydrodynamic bearing device, the width of the axial gap is set by adjusting the axial relative position of the lid member with respect to the bearing member at a micro-order level. Therefore, when the lid member is fitted to the bearing member, in order to accurately set the width of the axial gap, it is necessary to temporarily fix both with an adhesive or the like to the extent that the two cannot smoothly move relative to each other. . However, in this case, there are problems that a multi-step process is required for setting the width of the axial gap and the manufacturing cost increases, and the width of the axial gap may not be set with high accuracy. On the other hand, with each of the methods described above, even if the gap member is fitted to the bearing member, the width of the axial gap can be set easily and accurately without temporarily fixing the lid member to the bearing member. Can do.

  As described above, according to the present invention, in this type of hydrodynamic bearing device, it is possible to easily and accurately set the width of the axial gap. As a result, it is possible to provide a hydrodynamic bearing device that further increases the rotational accuracy in the thrust direction.

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. It is the schematic which shows the assembly process of a hydrodynamic bearing apparatus. (A) is a schematic diagram showing the positioning of each component of the hydrodynamic bearing device, and (b) is an enlarged cross-sectional view of the main part of FIG. (A) is a schematic diagram showing another example of the assembly process of the hydrodynamic bearing device, (b) is a schematic diagram showing a positioning state of each component when the assembly jig shown in (a) is used. It is. It is sectional drawing which shows the hydrodynamic bearing apparatus which concerns on 2nd 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. And the internal space of the bearing member 7 is filled with lubricating oil as a fluid. 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 as an engaging portion K that is disposed below the bearing member 7 and engages the bearing member 7 in the axial direction. Have. 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 cylindrical shape with both axial ends open, and integrally includes a cylindrical main body portion 7a and a cylindrical seal portion 7b disposed on the upper end inner diameter side of the main body portion 7a. The main body portion 7a has a stepped shape in which the inner peripheral surface 7a1 is formed in a cylindrical surface shape having a constant diameter, and the outer peripheral surface thereof is partitioned into a large-diameter outer peripheral surface 7a2 and a small-diameter outer peripheral surface 7a3 in the axial direction. Is done. Both outer peripheral surfaces 7a2, 7a3 are connected by a step surface 7a4 extending in a direction orthogonal to the axis.

  A seal space S is formed between the inner peripheral surface 7b1 of the seal portion 7b and the outer peripheral surface 2a1 of the opposed shaft portion 2a. The inner peripheral surface 7b1 of the seal portion 7b is formed in a tapered surface shape whose diameter is gradually reduced downward, while the outer peripheral surface 2a1 of the shaft portion 2a is formed in a cylindrical surface shape having a constant diameter. Accordingly, the seal space S has a tapered shape in which the radial dimension is gradually reduced downward.

  As shown in FIG. 3, radial bearing surfaces A <b> 1 and A <b> 2 that form radial bearing gaps between the inner circumferential surface 7 a <b> 1 of the main body portion 7 a of the bearing member 7 and the outer circumferential surface 2 a <b> 1 of the opposed shaft portion 2 a are axially provided. The radial bearing surfaces A1 and A2 are respectively provided with radial dynamic pressure generating portions formed by arranging a plurality of dynamic pressure grooves Aa1 and Aa2 in a herringbone shape. These radial bearing surfaces A1 and A2 are surfaces that define the outer diameter dimension of the radial bearing gap in the present invention. The upper dynamic pressure groove Aa1 is formed asymmetrically in the axial direction in which the axial dimension X1 of the upper region is larger than the axial dimension X2 of the lower region with respect to the axial center m. Aa2 is formed symmetrically in the axial direction, and the axial dimension of the upper and lower regions thereof is equal to the axial dimension X2. With this configuration, when the shaft member 2 rotates, the lubricating oil filled between the inner peripheral surface 7a1 of the bearing member 7 and the outer peripheral surface 2a1 of the shaft portion 2a is pushed downward (unbalanced pumping ability).

  The lower end surface 7a5 of the main body 7a is provided with a thrust bearing surface B that forms a first thrust bearing gap between the lower end surface 7a5 and the upper end surface 2b1 of the opposing flange portion 2b, and the thrust bearing surface B has a thrust dynamic pressure. A generating part is formed. The thrust dynamic pressure generating portion has a herringbone shape as shown in FIG. 4 and includes a plurality of dynamic pressure grooves Ba bent in a V shape and a hill portion shown by cross hatching in the drawing to divide the groove in the circumferential direction. Alternatingly arranged.

  The bearing member 7 having the above configuration is injection-molded with a resin material, and the radial dynamic pressure generating portion provided on the radial bearing surfaces A1 and A2 and the thrust dynamic pressure generating portion provided on the thrust bearing surface B are simultaneously molded with the mold. Molded. The resin material used for molding the bearing member 7 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 polyphenylsulfone (PPSU) is used. What used amorphous resin as base resin can be used. This resin material can be blended with various fillers as necessary, for example, reinforcing materials such as glass fibers, and conductive fillers such as carbon black, graphite, and carbon nanomaterials. In addition, in the present embodiment, since the conductivity is ensured by the lid member 10, a conductive filler is basically unnecessary. However, if there is no adverse effect on the formability of the bearing member 7 and there is no problem in terms of cost, a conductive filler may be blended.

  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 small-diameter outer peripheral surface 7a3 of the bearing member 7 (main body portion 7a) 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 7a1 of the bearing member 7 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 Ca bent in a V shape and hill portions shown by cross hatching in the drawing to divide the groove in the circumferential direction. Alternatingly arranged.

  As described above, since the plate portion 10a of the lid member 10 forms the second thrust bearing portion T2, the large-diameter outer peripheral surface of the bearing member 7 is required in order to ensure the desired bearing performance and thus the motor performance. The perpendicularity of the lower end surface (the outer bottom surface of the lid member 10) 10a2 of the plate portion 10a of the lid member 10 with respect to 7a2 is important. Therefore, the perpendicularity is set to 10 μm or less.

  In addition, although the said perpendicularity intends the squareness prescribed | regulated to JISB0621, in this embodiment, the perpendicularity obtained by measuring with the following procedures is made to become 10 micrometers or less. . First, while rotating the hydrodynamic bearing device 1 in an inverted state, the cylindricity (outer diameter dimension) of the large-diameter outer peripheral surface 7a2 of the bearing member 7 is set in the axial direction 3 by using a probe arranged on the outer diameter side of the bearing member 7. Measurement is performed at a location, and a virtual central axis is set based on the measurement data. Next, the amount of deflection at the predetermined position in the radial direction of the lid member 10 (strictly speaking, the amount of deflection with respect to a virtual plane orthogonal to the virtual central axis) is arranged on the bottom side of the lid member 10 while rotating the hydrodynamic bearing device 1. Measure with a probe. Then, an analysis is performed based on each measurement data described above, and a squareness is calculated.

  The upper end surface 10b1 of the cylindrical portion 10b and the step surface 7a4 of the bearing member 7 face each other in the axial direction with 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 7a5 of the bearing member 7, 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.

  In the stopped state of the hydrodynamic bearing device 1 composed of the above constituent members, the lower end surface 2b2 of the flange portion 2b of the shaft member 2 is in contact with the upper end surface 10a1 of the plate portion 10a of the lid member 10, A second axial gap δ2 having a predetermined width is provided between the upper end surface 2b1 of the flange portion 2b and the lower end surface 7a5 of the bearing member 7 as shown in an enlarged view in FIG. 2 (this second shaft). The direction gap δ2 corresponds to the above-described axial gap). When the shaft member 2 rotates, the gap width of the second axial gap δ2 is between the upper end surface 2b1 of the flange portion 2b and the lower end surface 7a5 of the bearing member 7, and the lower end surface 2b2 of the flange portion 2b and the lid. It is equal to the total amount of gap widths of the first and second thrust bearing gaps formed between the upper end surface 10a1 of the plate portion 10a of the member 10 and is set to 20 μm in this embodiment.

  In the hydrodynamic bearing device 1 having the above-described configuration, when the shaft member 2 rotates, the radial bearing surfaces A1 and A2 provided at two positions above and below the inner peripheral surface 7a1 of the bearing member 7 and the shafts opposed thereto. Radial bearing gaps are formed between the outer peripheral surface 2a1 of the portion 2a. 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 Aa1 and Aa2. As a result, the radial bearing portions R1 and R2 that support the shaft member 2 in the radial direction in a non-contact manner. 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 7a5 of the bearing member 7 and the upper end surface 2b1 of the flange portion 2b, and between 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 thrust bearing gaps is increased by the dynamic pressure action of the dynamic pressure grooves Ba and Ca. As a result, the first thrust bearing portion that supports the shaft member 2 in a non-contact manner in both thrust directions. T1 and second thrust bearing portion T2 are formed.

  In order to balance the support capability between the first thrust bearing portion T1 and the second thrust bearing portion T2 and stabilize the rotational accuracy in the thrust direction, the clearance width of the first thrust bearing gap and the second thrust bearing The gap width of the gap is set to a substantially uniform width (in this embodiment, both are 10 μm).

  Further, since the seal space S has a tapered shape with the radial dimension gradually reduced downward (inside the bearing member 7), the lubricating oil in the seal space S is pulled into the seal space by a capillary force action. S is pulled toward the narrowing direction, that is, toward the inside of the bearing member 7. Further, the seal space S has an absorption function (buffer function) of a volume change amount associated with a temperature change of the lubricating oil that fills the internal space of the bearing member 7, and the oil level of the lubricating oil is within a range of the assumed temperature change. Is always held in the seal space S. From these configurations, lubricating oil leakage from the bearing member 7 is effectively prevented.

  When the shaft member 2 rotates, the lubricating oil filled in the gap formed between the inner peripheral surface 7a1 of the bearing member 7 and the outer peripheral surface 2a1 of the shaft portion 2a is unbalanced in the pumping ability of the radial dynamic pressure generating portion. Is pushed down by. 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. 6), 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 FIG. 6 in an enlarged manner, the communication holes 9 that are opened in both end faces 2b1 and 2b2 of the flange portion 2b are provided. As a result, the lubricating oil can go back and forth between the thrust bearing gaps via the communication hole 9, so that the collapse of the pressure balance between the thrust bearing gaps can be eliminated quickly, and the thrust bearing portions T1 and T2 can be The thrust support force can be balanced.

  The communication hole 9 of this embodiment is composed of a radial portion 9a and an axial portion 9b, and is opened to the inner diameter side of the thrust bearing surfaces B and C (thrust dynamic pressure generating portions) while avoiding the formation region. It exhibits a bent shape. More specifically, the outer diameter end of the radial direction portion 9a is formed by the upper end surface 2b1 of the flange portion 2b, the lower end side inner peripheral chamfer (chamfering) of the bearing member 7, and the crushed portion 2a3 provided at the lower end of the shaft portion 2a. The axial direction portion 9b connected to the inner diameter end of the radial direction portion 9a 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. Yes. 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 9 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, since the pressure in the bottom space P tends to increase, the dynamic pressure groove Ca that forms the second thrust bearing portion T2 has been frequently used conventionally. 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 Ca forming the second thrust bearing portion T2 in the herringbone shape shown in FIG. On the other hand, in the first thrust bearing portion T1, since this type of problem does not occur, the dynamic pressure groove Ba 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 (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 7a2 of the bearing member 7 are formed of a metal material such as an aluminum alloy. For example, by adhering and fixing to the inner peripheral surface of the motor. At this time, if the outer diameters of the bearing member 7 and the lid member 10 are made equal, they can be reliably 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. The bearing member 7 does not necessarily need to be 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.

  The hydrodynamic bearing device 1 having the above configuration is assembled as follows, for example.

  FIG. 7 shows an assembly process of the hydrodynamic bearing device 1. The assembly jig shown in the figure includes a first jig 21 placed on the base 20, a second jig 22 configured to be able to be expanded and contracted by a suitable drive mechanism (not shown), and a suitable jig (not shown). The main part is composed of the third jig 23 that can be moved up and down by a simple driving mechanism. The thickness of the first jig 21 is set to the same dimension as the gap width of the second axial gap δ2. Therefore, in the present embodiment in which the gap width of the second axial gap δ2 is 20 μm, the thickness of the first jig 21 is 20 μm. In FIG. 7, the thickness of the first jig 21 is exaggerated for easy understanding.

  In the assembly jig having the above configuration, first, the lid member 10 is placed on the first jig 21, and the shaft member 2 is placed on the plate portion 10 a of the lid member 10. Next, an adhesive (an epoxy adhesive in the present embodiment) is applied to at least one of the small-diameter outer peripheral surface 7a3 of the bearing member 7 and the inner peripheral surface 10b2 of the cylindrical portion 10b, and the bearing member is applied to the inner peripheral surface 10b2 of the cylindrical portion 10b. 7 small diameter outer peripheral surface 7a3 is fitted.

  After fitting the small-diameter outer peripheral surface 7a3 of the bearing member 7 to the inner peripheral surface 10b2 of the cylindrical portion 10b, the bearing member 7 is pushed forward to bring the lower end surface 7a5 of the bearing member 7 into contact with the upper end surface 2b1 of the flange portion 2b. The gap width between the two thrust bearing gaps (the gap width of the second axial gap δ2) is set to zero. At this time, the upper end surface 10b1 of the cylindrical portion 10b and the stepped surface 7a4 of the bearing member 7 are not in contact with each other, that is, a first axial gap δ1 having a predetermined width is formed between these two axially opposed surfaces. In addition, the axial dimension of the cylindrical portion 10b is set to be a predetermined amount smaller than the sum of the axial dimension of the thin portion of the bearing member 7 (the portion having the small-diameter outer peripheral surface 7a3) and the thickness of the flange portion 2b. .

  Here, in the present embodiment in which the bearing member 7 and the lid member 10 are bonded to each other with a gap, the inner peripheral surface 10b2 of the cylindrical portion 10b is in a gap-fitted state with respect to the small-diameter outer peripheral surface 7a3 of the bearing member 7, and accordingly, A gap in the radial direction having a predetermined width is formed between them (the width at this time is a value obtained by subtracting the radial dimension of the small-diameter outer peripheral surface 7a3 from the radial dimension of the inner peripheral surface 10b2 of the cylindrical portion 10b).

  Next, as shown in FIG. 8A, the diameter of the second jig 22 is reduced to constrain the large-diameter outer peripheral surface 7a2 of the bearing member 7, and the axial movement of the bearing member 7 is restricted. The first jig 21 interposed between the lid member 10 and the lid member 10 is removed. After removing the first jig 21 and lowering the third jig 23 to pressurize the shaft member 2 downward, the lid member 10 is lowered by the pressure applied by the shaft member 2 and the outside of the lid member 10 is removed. The bottom surface 10b2 contacts the base 20. Accordingly, as shown in FIG. 8B, a second axial gap δ2 having a predetermined width (20 μm in this embodiment) is formed between the upper end surface 2b1 of the flange portion 2b and the lower end surface 7a5 of the bearing member 7. It is formed. In this way, the axial relative position of the lid member 10 with respect to the bearing member 7 is always managed to be constant. Even in this embodiment in which the lid member 10 is fitted into the bearing member 7 with a gap, the width of the second axial gap δ2 can be easily and accurately set without temporarily fixing the lid member 10 to the bearing member 7. Can do.

  In this embodiment in which the lid member 10 is fitted to the outer periphery of the bearing member 7, when the first jig 21 is removed, the lid member 10 and the shaft member 2 are naturally lowered by their own weights. It is also possible. Therefore, it is not always necessary to press the shaft member 2 downward with the third jig 23. However, the inner peripheral surface 10b2 of the cylindrical portion 10b is used as a bearing as long as the surface accuracy of the lower radial bearing surface A2 (radial dynamic pressure generating portion) formed on the inner peripheral surface 7a1 of the bearing member 7 is not adversely affected. It is also possible to lightly press into the small-diameter outer peripheral surface 7a3 of the member 7. In such a case, it is difficult to naturally lower the lid member 10 with its own weight, so it is desirable to lower the shaft member 2 and further the lid member 10 using the third jig 23.

  By setting the width of the second axial gap δ2 as described above, the first axial gap δ1 is formed between the end surface 10b1 of the cylindrical portion 10b of the lid member 10 and the step surface 7a4 of the bearing member 7. (See FIG. 2). When the epoxy adhesive is supplied to the first axial gap δ1 while this state is maintained, and then baking is performed, the width setting operation of the second axial gap δ2 (first and second thrust bearing gaps) is completed. At the same time, the lid member 10 and the bearing member 7 are completely bonded and fixed. Then, the fluid bearing device 1 shown in FIG. 2 is completed by filling the internal space of the bearing member 7 with lubricating oil as a fluid. At this time, since the first axial gap δ1 is sealed with the adhesive, oil leakage from the fitting portion between the inner peripheral surface 10b2 of the cylindrical portion 10b and the small-diameter outer peripheral surface 7a3 of the bearing member 7 is ensured. Is prevented.

  In the above description, the case where the lid member 10 and the bearing member 7 are bonded and fixed using an epoxy adhesive has been described. However, if a predetermined fixing strength (adhesive strength) can be secured between the two, the epoxy 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.

  Further, the bearing member 7 and the lid member 10 can be bonded and fixed by a procedure different from the above. The specific procedure is as follows. First, after fitting the cylindrical portion 10b of the lid member 10 to the outer periphery of the bearing member 7 to set the width of the second axial gap δ2, an adhesive is supplied from the first axial gap δ1, and the bearing member 7 is set. The adhesive is drawn into the radial gap by utilizing the capillary force of the radial gap between the small-diameter outer peripheral surface 7a3 and the inner peripheral surface 10b2 of the cylindrical portion 10b. Thereafter, the adhesive interposed between the radial gap and further the first axial gap δ1 is cured to fix them together.

  As described above, a predetermined width between the bearing member 7 and the cylindrical portion 10b of the lid member 10 (specifically, the bearing member 7, the flange portion 2b as the engaging portion K, and the lid member 10 are in the axial direction. Each of which determines the gap width of the second axial gap δ2 by interposing the first axial gap δ1 of a value that allows the axial movement of the bearing member 7 and the lid member 10 until they contact each other. Variations in the axial dimension of the member can be absorbed by the first axial gap δ1. Therefore, the axial relative position of the lid member 10 with respect to the bearing member 7 can be made constant as long as the gap width of the first axial gap δ1 is sufficiently secured. Instead, the second axial gap δ2 having a predetermined width can be always provided between the upper end surface 2b1 of the flange portion 2b of the shaft member 2 and the lower end surface 7a5 of the bearing member 7. In the present embodiment in which the thrust bearing portion is constituted by a dynamic pressure bearing, the gap width of the second axial gap δ2 is the total amount of the gap widths of the first and second thrust bearing gaps. Therefore, since the gap width between the thrust bearing gaps can be reliably managed to a predetermined value, the rotational accuracy in the thrust direction can be further improved.

  In order to ensure sufficient support accuracy in the thrust direction, the crossing of the axial relative position of the lid member 10 with respect to the bearing member 7 in this type of hydrodynamic bearing device, that is, the variation in the gap width of the second axial gap δ2 is within ± 5 μm. Although it is set to (-5 μm or more and +5 μm or less), the required accuracy can be easily satisfied with the configuration of the present invention.

  Further, since the cylindrical portion 10b of the lid member 10 is fixed to the outer peripheral surface (small-diameter outer peripheral surface 7a3) of the bearing member 7, the cylindrical portion of the lid member is fixed to the inner peripheral surface of the bearing member (housing) as in the prior art. Compared to the case, the fixed area between the two members can be increased by the difference in diameter between the inner peripheral surface and the outer peripheral surface, and the axial dimension of the cylindrical portion 10b is increased in order to increase the fixed area for the bearing member 7. This is sufficient, and the shape of the bearing member 7 is not particularly complicated. Moreover, since only the cylinder part 10b of the cover member 10 is arrange | positioned at the outer diameter side of the flange part 2b as the engaging part K, the flange part 2b can be enlarged in diameter. Therefore, the support area in the thrust direction can be increased by increasing the support area of the thrust bearing portions T1 and T2.

  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 the room for material selection is widened when examining the molding material of the bearing member 7, and the hydrodynamic bearing device 1. Design freedom increases. In order to impart conductivity to the bearing member 7 made of resin, it is customary to blend an expensive conductive filler in the resin material, but in the present invention, this kind of conductive filler is blended. Since it can be made unnecessary or the blending amount can be reduced, an increase in material cost can be suppressed.

  The hydrodynamic bearing device 1 having the above-described configuration can also be assembled as follows. However, below, it demonstrates centering on a different point from the procedure mentioned above, and abbreviate | omits description suitably about the overlapping point.

  FIG. 9A is a modification of the assembly jig shown in FIG. 7, and the first jig 21 that supports the outer bottom surface 10a2 of the lid member 10 can be moved up and down by an appropriate drive mechanism (not shown). The configuration of the assembly jig shown in FIG. 7 is different from that of the assembly jig shown in FIG. 7 in that it is provided and a restriction member 24 that regulates the descending amount of the first jig 21 is provided. One end of the first jig 21 is opened on the upper surface of the first jig 21, and the other end is engaged (contacted) with the intake passage 21a connected to a suction device (not shown) and the regulating member 24 in the axial direction. Engaging portion 21b is provided. In the state where the first jig 21 is at the origin position, the axial separation distance ε1 between the engaging portion 21b of the first jig 21 and the regulating member 24, that is, the descendable amount of the first jig 21 is formed. It is set to the same dimension as the gap width of the second axial gap δ2.

  In the assembly jig having the above configuration, first, similarly to the above-described assembly method, the lid member 10 and the shaft member 2 are sequentially arranged on the first jig 21, and the small-diameter outer peripheral surface 7a3 of the bearing member 7 is disposed on the lid member. 10 is fitted to the inner periphery of the cylinder portion 10b, and then the lid member 10, the flange portion 2b of the shaft member 2, and the bearing member 7 are brought into contact with each other in the axial direction so that the gap width between the two thrust bearing gaps becomes zero. To do. Next, as shown in FIG. 9B, the second jig 22 is reduced in diameter to restrain the large-diameter outer peripheral surface 7a2 of the bearing member 7, and the engagement of the bearing member 7 is restricted in the axial direction. The first jig 21 is lowered until the portion 21b engages (contacts) with the regulating member 24 in the axial direction. At this time, a suction force is applied from the suction device (not shown) to the lid member 10 through the intake passage 21a to attract the lid member 10 to the first jig 21, and the third jig 23 is lowered to move the shaft. The lid member 10 is lowered integrally with the first jig 21 by pushing the member 2 downward. Thus, a second axial gap δ2 having a predetermined width (20 μm in this embodiment) is formed between the upper end surface 2b1 of the flange portion 2b and the lower end surface 7a5 of the bearing member 7.

  If the first jig 21 is lowered while the lid member 10 is attracted to the first jig 21, the amount by which the lid member 10 is lowered, that is, the gap width of the second axial gap δ2 is accurately managed. However, it is not always necessary to use the suction of the lid member 10 and the pressurization of the shaft member 2 by the third jig 23, and only one of them may be used.

  At the same time when the second axial gap δ2 is formed, an adhesive is supplied to the first axial gap δ1 formed between the end surface 10b1 of the cylindrical portion 10b of the lid member 10 and the stepped surface 7a4 of the bearing member 7. Then, after baking, the lid member 10 and the bearing member 7 are completely bonded and fixed, and at the same time, the width setting operation of the second axial gap δ2 (first and second thrust bearing gaps) is completed.

  If the assembling method as described above is employed, the second shaft can be secured without temporarily fixing the lid member 10 to the bearing member 7 even when the lid member 10 is clearance-fitted to the bearing member 7 as described above. The width of the direction gap δ2 can be easily and accurately set.

  FIG. 10 shows a second embodiment of a hydrodynamic bearing device 1 to which the present invention is applied. The hydrodynamic bearing device 1 shown in the figure mainly has a thrust bearing portion T that supports the shaft member 2 in the thrust direction, that is, a so-called pivot bearing, that is, the lower end surface 2a3 of the shaft portion 2a is formed in a convex spherical shape. 2 is different from the embodiment shown in FIG. 2 in that the convex spherical lower end surface 2a3 is contacted and supported by the upper end surface 10a1 of the plate portion 10a of the lid member 10. Also in this embodiment, the shaft member 2 is provided with a flange portion 2b as an engagement portion K that engages with the bearing member 7 in the axial direction integrally or separately, and when the bearing is stopped, an upper side of the flange portion 2b is provided. A second axial gap (axial gap) δ2 having a predetermined width is formed between the end face 2b1 and the lower end face 7a5 of the bearing member 7.

  Although detailed illustration is omitted, also in the hydrodynamic bearing device 1 of this embodiment, the second axial gap δ2 having a predetermined width can be formed by assembling by the above-described method.

  In the above embodiment, resin is used as the molding material for the bearing member 7. However, if there is no problem in cost and the like, for example, a low melting point metal material such as magnesium alloy or aluminum alloy is used for the bearing member 7. It is also possible to injection mold.

  Further, in the above-described embodiment, the bearing member 7 is formed with respect to the surfaces (radial bearing surface, thrust bearing surface, and seal surface) that form the radial bearing gap, the thrust bearing gap, and the seal space S, respectively, and further to the motor bracket 6. Although the mounting surface is also integrally formed, the fluid bearing device 1 to which the present invention can be applied is not limited to the bearing member 7 having the above-described configuration. Although detailed illustration is omitted, for example, a portion (sleeve portion) having at least a surface that forms a radial bearing gap, and a housing portion that has the sleeve portion disposed on the inner periphery and has a mounting surface for the motor bracket 6 are provided. The present invention can also be suitably applied to a hydrodynamic bearing device that uses a bearing member.

  In the above embodiment, the dynamic pressure generating portions that generate the dynamic pressure action in the radial bearing gap and the thrust bearing gap are the inner peripheral surface 7a1, the lower end surface 7a5, and the lid of the bearing member 7 (main body portion 7a), respectively. Although formed on the upper end surface 10a1 of the plate portion 10a of the member 10, a part or all of these dynamic pressure generating portions are opposed to each other through a bearing gap, that is, the outer peripheral surface 2a1 of the shaft portion 2a and the end surface of the flange portion 2b. You may form in 2b1, 2b2.

  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 embodiment shown in FIG. 2, the case where the thrust bearing portions T1 and T2 made of the dynamic pressure bearing are configured by the dynamic pressure action by the dynamic pressure groove such as the herringbone shape has been described. Any one or both of the thrust bearing portions T1 and T2 can be configured by other known dynamic pressure bearings such as a mold bearing.

DESCRIPTION OF SYMBOLS 1 Fluid dynamic bearing apparatus 2 Shaft member 2a Shaft part 6 Motor bracket 7 Bearing member 7a Main body part 7b Seal part 9 Communication hole 10 Lid member 10b Cylindrical part A1, A2 Radial bearing surface B, C Thrust bearing surface K Engagement part S Seal space R1, R2 Radial bearing portions T, T1, T2 Thrust bearing portion δ1 First axial clearance δ2 Second axial clearance

Claims (11)

Between the bearing member having both ends opened, the shaft member having an engaging portion inserted in the inner periphery of the bearing member and engaged in the axial direction with the bearing member, and the inner peripheral surface of the bearing member and the outer peripheral surface of the shaft member A radial bearing portion that supports the shaft member in the radial direction with an oil film formed in the radial bearing gap of the shaft, and a thrust bearing portion that is fitted to the bearing member to close one end opening of the bearing member and supports the shaft member in the thrust direction In the hydrodynamic bearing device, the lid member has a cylindrical portion that extends in the axial direction, and the engaging portion is disposed on the inner diameter side of the cylindrical portion.
A hydrodynamic bearing device characterized in that an axial gap is interposed between the bearing member and the cylindrical portion of the lid member so that the axial relative position of the lid member with respect to the bearing member is constant.   Allow the axial clearance of the bearing member and the lid member until the gap width of the axial gap is in contact with the bearing member and the engaging portion, and one end of the shaft member on the bearing closing side and the lid member in the axial direction. The hydrodynamic bearing device according to claim 1, wherein the fluid bearing device is set to a value to be determined.   The hydrodynamic bearing device according to claim 1, wherein the perpendicularity of the outer bottom surface of the lid member with respect to the outer peripheral surface of the bearing member is 10 μm or less.   The hydrodynamic bearing device according to claim 1, wherein a tolerance of an axial relative position is within ± 5 μm.   The cylindrical portion of the lid member is fitted to the outer peripheral surface of the bearing member with a tightening margin that does not affect the surface accuracy of the surface defining the outer diameter dimension of the radial bearing gap, and the lid member and the bearing member are bonded and fixed. The hydrodynamic bearing device according to 1.   The hydrodynamic bearing device according to claim 5, wherein the cylindrical portion of the lid member and a part or all of the surface defining the outer diameter of the radial bearing gap of the bearing member overlap in the axial direction.   A thrust bearing gap of the first thrust bearing portion is formed between one end surface of the engaging portion and the end surface of the bearing member facing the engaging portion, and the other end surface of the engaging portion and the end surface of the lid member facing the first thrust bearing portion. The hydrodynamic bearing device according to claim 1, wherein a thrust bearing gap of the second thrust bearing portion is formed therebetween.   The hydrodynamic bearing device according to claim 7, wherein a gap width of a thrust bearing gap of the first thrust bearing portion and a gap width of a thrust bearing gap of the second thrust bearing portion are set to be substantially uniform. Between the bearing member having both ends opened, the shaft member having an engaging portion inserted in the inner periphery of the bearing member and engaged in the axial direction with the bearing member, and the inner peripheral surface of the bearing member and the outer peripheral surface of the shaft member A radial bearing portion that supports the shaft member in the radial direction with an oil film formed in the radial bearing gap of the shaft, and a thrust bearing portion that is fitted to the bearing member to close one end opening of the bearing member and supports the shaft member in the thrust direction In the method of manufacturing a hydrodynamic bearing device, the lid member has a cylindrical portion that extends in the axial direction, and the engaging portion is disposed on the inner diameter side of the cylindrical portion.
After the outer bottom surface of the lid member is supported by a jig placed on the base, the bearing member and the engaging portion, and the bearing closing end of the shaft member and the lid member are brought into contact with each other in the axial direction. A method for manufacturing a hydrodynamic bearing device, comprising the step of removing the jig in a state where axial movement of the bearing member is restricted. Between the bearing member having both ends opened, the shaft member having an engaging portion inserted in the inner periphery of the bearing member and engaged in the axial direction with the bearing member, and the inner peripheral surface of the bearing member and the outer peripheral surface of the shaft member A radial bearing portion that supports the shaft member in the radial direction with an oil film formed in the radial bearing gap of the shaft, and a thrust bearing portion that is fitted to the bearing member to close one end opening of the bearing member and supports the shaft member in the thrust direction In the method of manufacturing a hydrodynamic bearing device, the lid member has a cylindrical portion that extends in the axial direction, and the engaging portion is disposed on the inner diameter side of the cylindrical portion.
After the outer bottom surface of the lid member is supported by a jig, the bearing member and the engaging portion, and the bearing member closing end of the shaft member and the lid member are brought into contact with each other in the axial direction, and then the axial movement of the bearing member is performed. A method of manufacturing a hydrodynamic bearing device, comprising a step of moving the jig a predetermined amount in a direction away from the bearing member in a state where the pressure is regulated.   The method of manufacturing a hydrodynamic bearing device according to claim 10, wherein the jig is moved by a predetermined amount in a direction away from the bearing member in a state where the lid member is attracted to the jig.

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