JP2009168147A - Dynamic pressure bearing device and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To accurately set clearance dimensions of a thrust bearing clearance and a radial bearing clearance formed in both sides of a flange portion. <P>SOLUTION: This dynamic pressure bearing device is provided with: a shaft member 2 having a shaft portion 2a and the flange portion 2b; a housing 7 having a bottom 7b closing a lower end and an inner periphery on which a bearing sleeve 8 is fixed; a first thrust bearing clearance formed between the flange portion 2b and the bearing sleeve 8; and a second thrust bearing clearance formed between the flange portion 2b and the bottom 7b of the housing 7. When the dynamic pressure bearing device is manufactured, a small diameter portion 9 for temporary fixation is arranged around the inner periphery of the housing 7, and the bearing sleeve 8 is pushed to a position where the bearing sleeve 8 abuts on the flange portion 2b and the flange portion 2b abuts on the bottom 7b of the housing 7 while pressure-fitting the bearing sleeve 8 into the small diameter portion 9. The bearing sleeve 8 is relatively moved from this abutting position to a direction separating from the bottom 7b while maintaining the pressure-fitting state, thereby setting the total δ of both the thrust bearing clearances to predetermined dimensions. <P>COPYRIGHT: (C)2009,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 so as to be relatively rotatable by a hydrodynamic action of a fluid generated in a bearing gap. This type of bearing device is particularly excellent in rotational accuracy, quietness, etc. during high-speed rotation, and is suitably used as a bearing device for motors mounted on various electrical devices including information devices. Specifically, as a bearing device for a spindle motor in magnetic disk devices such as HDD, optical disk devices such as CD-ROM, CD-R / RW, DVD-ROM / RAM, magneto-optical disk devices such as MD and MO, etc. Alternatively, it is preferably used as a bearing device for a motor such as a polygon scanner motor of a laser beam printer (LBP), a color wheel motor of a projector, or a fan motor.

  For example, in a hydrodynamic bearing device incorporated in a spindle motor such as an HDD, a radial bearing portion that supports a shaft member in the radial direction and a thrust bearing portion that supports the shaft member in a thrust direction may be configured by a hydrodynamic bearing. is there. As a thrust bearing portion in this type of hydrodynamic bearing device, for example, a first portion is provided between one end surface of a flange portion provided at one end of a shaft portion and one end surface of the bottom portion of the housing facing the one end surface in the thrust direction. It is known that a thrust bearing gap is formed and a second thrust bearing gap is formed between the other end face of the flange portion and one end face of the bearing sleeve facing the other end face in the thrust direction.

  As means for managing these thrust bearing gaps with high accuracy, for example, Japanese Patent Application Laid-Open No. 2003-239974 (Patent Document 1) discloses a housing for a bearing sleeve based on the inner bottom surface of a bottomed cylindrical housing. A means for setting the first thrust bearing gap and the second thrust bearing gap to a predetermined size by setting the position with respect to is disclosed. Specifically, one end surface of the flange portion is brought into contact with the inner bottom surface of the housing, and one end surface of the bearing sleeve is brought into contact with the other end surface of the flange portion. From this position, the bearing sleeve is connected to the first thrust bearing gap. A means is disclosed in which the sum of the thrust bearing gaps is set to a predetermined dimension by moving in the axial direction relative to the housing by a dimension corresponding to the total amount with the second thrust bearing gap.

Further, as another means for managing the thrust bearing gap with high accuracy, for example, Japanese Patent Application Laid-Open No. 2006-71029 (Patent Document 2) discloses a bearing sleeve that forms a thrust bearing gap with a flange portion. A hydrodynamic bearing device is disclosed in which a housing is provided with a stepped portion that abuts an end surface and has a predetermined axial dimension. Then, as a method of gap clearance of this bearing device, the bearing sleeve is pushed into the inner periphery of the housing until the one end surface of the bearing sleeve comes into contact with the end surface of the step portion provided on the inner periphery of the housing. A method is disclosed in which an axial fixed position is set, whereby the thrust bearing gap is managed as the difference between the axial dimension of the stepped portion and the axial width of the flange portion.
JP 2003-239974 A JP 2006-71029 A

  By the way, when setting this kind of thrust bearing gap, it is necessary to be able to move the bearing sleeve while maintaining an appropriate posture (for example, coaxiality) with respect to the housing. For this reason, as described in Patent Documents 1 and 2, it is usual to carry out the above-described clearance operation while press-fitting a bearing sleeve into the inner periphery of the housing. However, when positioning the bearing sleeve with press fitting, depending on the size of the tightening allowance, the inner diameter of the bearing sleeve may change due to the press fitting (most of which the inner diameter is reduced). Usually, the radial bearing gap is as small as several μm to several tens of μm. Therefore, even a slight change in the inner diameter due to press-fitting may affect the radial bearing gap and cause a decrease in the bearing performance.

  Here, since both of the hydrodynamic bearing devices disclosed in Patent Documents 1 and 2 press-fit a cylindrical bearing sleeve into the cylindrical housing, the press-fitting is performed over the entire inner peripheral surface of the housing. It is considered a thing. In this case, when the bearing sleeve is fixed to the housing, the inner diameter of the bearing sleeve is reduced, and the radial bearing gap is reduced. In addition, in any of the above patent documents, no consideration is given to the reduction of the inner diameter of the bearing sleeve due to press fitting.

  The above-described problem is particularly noticeable when the hydrodynamic bearing device is applied to information equipment such as an HDD. That is, in the field of HDD and the like, the number and size of the disks tend to increase with the recent increase in capacity. For this reason, in the hydrodynamic bearing device that should support the rotation of the disk, for example, by changing the housing from resin to metal in response to the increase in the rotation weight, the deformation of the inner peripheral surface of the bearing sleeve due to press fitting increases. Further, as the capacity increases, the weight of the rotating body including the shaft increases, so that it is necessary to improve the pull-out strength of the bearing sleeve, and in order to improve the strength, it is essential to increase the tightening allowance. For these reasons, the deformation of the inner peripheral surface of the bearing sleeve, particularly the radial bearing surface, is increased.

  In view of the above circumstances, according to the present invention, in this type of hydrodynamic bearing device, not only the thrust bearing gaps formed on both sides of the flange portion but also the radial bearing gaps are set with high accuracy. This is a technical issue.

  The solution to the above-described problem is achieved by a fluid dynamic bearing device according to one aspect of the present invention. That is, this hydrodynamic bearing device has a shaft member having a shaft portion and a flange portion, a bearing sleeve having the shaft portion inserted into the inner periphery, and a bottom portion closing one end in the axial direction, and fixing the bearing sleeve to the inner periphery. The first thrust bearing gap formed between one end surface of the flange portion facing the axial direction and the one end surface of the bearing sleeve, the other end surface of the flange portion facing the axial direction, and the bottom portion of the housing. And a second thrust bearing gap formed between the first end face and the first and second thrust bearing gaps, each of which is set to a predetermined size. The fixing means is fixed to the housing, and one fixing means is constituted by a small diameter portion for temporary fixing provided on the inner periphery of the housing, and the small diameter portion presses the bearing sleeve into the housing. It characterized with respect a part for temporarily fixing the grayed. Here, “temporarily fixed” means that the bearing sleeve can move in the axial direction under a predetermined load in the axial direction, and in the state where the load in the axial direction is released, the predetermined axial direction of the housing. It means a state that can be held in position. Further, the “small diameter portion for temporary fixing” means a small diameter portion for imparting a press-fitting allowance to the bearing sleeve to such an extent that the above-described “temporary fixing” state can be realized.

  According to such a configuration, the axial fixing position of the bearing sleeve with respect to the housing can be determined at a stage before being fixed by the other fixing means, that is, only at the stage of temporary fixing. Further, at that time, since the press-fitting area of the bearing sleeve is reduced as compared with the case where the bearing sleeve is press-fitted all over the inner peripheral surface of the housing, the resistance during press-fitting can be reduced. As a result, the load required to move the bearing sleeve in a predetermined direction can be reduced, the positioning accuracy at that time can be increased, and the thrust bearing gap can be set with high accuracy. Also, the deformation of the inner peripheral surface of the bearing sleeve due to the press-fitting is suppressed, and particularly the deformation of the radial bearing surface provided on the inner periphery of the bearing sleeve is suppressed to a small extent, and a predetermined radial bearing gap is secured between the shaft portion. be able to.

  Moreover, the solution of the above-described problem can be achieved by a method for manufacturing a hydrodynamic bearing device according to one aspect of the present invention. That is, the method for manufacturing the hydrodynamic bearing device includes a shaft member having a shaft portion and a flange portion, a bearing sleeve having the shaft portion inserted into the inner periphery, and a bottom portion that closes one end in the axial direction. A housing fixed to the periphery, a first thrust bearing gap formed between one end surface of the flange portion facing each other in the axial direction and one end surface of the bearing sleeve, and the other end surface of the flange portion facing each other in the axial direction In a method of manufacturing a hydrodynamic bearing device having a second thrust bearing gap formed between one end surface of a bottom portion of a housing, a small-diameter portion for temporary fixing is provided on the inner periphery of the housing, and a bearing is provided at the small-diameter portion. The sleeve is press-fit, and the bearing sleeve in the press-fit state is moved to a fixed position with respect to the housing so as to set the total amount of the first and second thrust bearing gaps to a predetermined size. .

  According to such a manufacturing method, the same matters as the matters regarding the hydrodynamic bearing device according to one aspect of the present invention already described apply, and therefore, the same effects as the effects of the bearing devices can be obtained. Can do.

  Further, when the above-described method is employed, the following means is suitable as a movement mode of the bearing sleeve to the fixed position with respect to the housing. That is, the bearing sleeve is brought into contact with the flange portion and the flange portion is brought into contact with the bottom portion of the housing, and then the bearing sleeve is moved away from the bottom portion while maintaining the press-fitted state. It is preferable to move to a fixed position.

  By moving the bearing sleeve in this way, each thrust bearing gap can be set with high accuracy and reliability without being affected by variations in the dimensions of the components of the hydrodynamic bearing device. Of course, the same applies to the hydrodynamic bearing device according to one aspect of the present invention described above, so the thrust bearing gap of the hydrodynamic bearing device positioned by the above-described method was set with high accuracy and reliability. It will be a thing.

  In the hydrodynamic bearing device according to the above configuration, the press-fitting region between the temporary fixing small-diameter portion and the bearing sleeve is formed at a position offset in the axial direction from the radial bearing surface provided on the inner periphery of the bearing sleeve. It is preferable that

  As described above, if a press-fitting region between the bearing sleeve and the small diameter portion is provided at a position that is axially deviated from the radial bearing surface, the inner peripheral surface of the bearing sleeve press-fitted into the small diameter portion other than the radial bearing surface. The region preferentially deforms toward the inner diameter side. Therefore, the radial bearing gap can be managed with high accuracy while minimizing the change in the inner diameter of the radial bearing surface.

  Note that the above configuration relating to the position where the press-fit region is formed includes, for example, a case where the small-diameter portion for temporarily fixing the small-diameter portion on the inner periphery of the bearing sleeve in a state where the total amount of the thrust bearing gap is set to a predetermined size. The radial bearing surface provided and the small diameter portion can be obtained by forming in advance at a predetermined position of the housing so that they are displaced in the axial direction. In other words, with the total amount of the thrust bearing gap set to a predetermined size, the small diameter portion is formed at a position where no radial bearing surface is included in the inner diameter side space of the small diameter portion. Obtainable.

  As described above, when the bearing sleeve is temporarily fixed to the housing, the fixing strength of the bearing sleeve with respect to the housing is increased by fixing the portion other than the portion temporarily fixed by press-fitting with the other fixing means, for example, laser welding. In such a case, however, a considerable amount of gap remains between the inner peripheral surface of the housing and the bearing sleeve. This gap not only leads to an increase in the amount of lubricating oil or the like retained in the hydrodynamic bearing device, but also becomes a space to be avoided as much as possible because the presence of the gap may deteriorate the vibration characteristics of the bearing. From such a viewpoint, it is preferable that the gap between the inner peripheral surface of the housing and the outer peripheral surface of the bearing sleeve is filled with an adhesive, and thereby the bearing sleeve is fixed to the housing. That is, it is preferable to use adhesive as the other fixing means, thereby fixing the bearing sleeve to the housing.

  Thus, if the gap between the housing and the bearing sleeve is used as an adhesive gap, the space that adversely affects the vibration characteristics due to the supply of the adhesive can be removed. Further, since the bonding area between the housing and the bearing sleeve can be as large as possible, the fixing strength between the housing and the bearing sleeve can be further increased. From the above points, the gap between the housing and the bearing sleeve is preferably filled with an adhesive as much as possible.

  Moreover, when using adhesive fixing together as mentioned above, it is preferable to provide a flow passage through which the adhesive can flow from the axial opening side to the closing side of the small diameter portion in the small diameter portion for temporary fixing. It is preferable to supply the adhesive to the axially closed side of the small diameter portion through this flow passage.

  As described above, if the small-diameter portion for temporary fixing is provided with the flow path of the adhesive, the adhesive supplied from the one end opening side of the housing is temporarily passed through the flow path when the bearing sleeve is temporarily fixed. It reaches to the axial blockage side. Accordingly, a sufficient amount of adhesive can be supplied not only to the axially open side of the small diameter portion but also to the gap between the housing and the bearing sleeve existing on the closed side, and the benefits of the above-described adhesive fixing can be sufficiently obtained. it can.

  Here, the small-diameter portion for temporary fixing may be formed integrally with the housing, or may be formed separately from the housing. Alternatively, the member having a small diameter portion may be formed separately from the housing, and the separate member may be fixed to the inner periphery of the housing so that the housing has a small diameter portion for temporary fixing.

  By forming the small diameter portion separately from the housing in this way, it is possible to separately consider the characteristics required for the housing and the characteristics required for the temporary fixing small diameter portion. Specifically, the housing is made of a material having a required strength required as a housing for a hydrodynamic bearing device, and the small diameter portion for temporary fixing has rigidity suitable for press-fitting temporary fixing with the bearing sleeve. Can be made of material.

  In this case, the small-diameter portion for temporary fixing can be formed by injection molding on the inner periphery of the housing.

  According to this method, for example, when a small-diameter portion that has been formed separately from the housing is integrated with the housing, it is not necessary to receive variations in individual component dimensions. It is possible to form a housing inner peripheral surface and a small-diameter portion having a highly accurate inner diameter simply by keeping them. In addition, the housing to be injection-molded is roughly formed as a blank material (unfinished product), and a molten material such as resin is injection-molded on the inner periphery of the blank material to integrally form a small-diameter portion for temporary fixing. After that, the inner peripheral surface of the housing including the small diameter portion can be finished with high accuracy. According to such means, the injection mold can be formed roughly, which is advantageous in terms of cost. The injection molding of the small diameter portion may be performed on the inner peripheral surface of the housing having a constant diameter. However, if the fixing force with the housing is to be increased, a concave portion (large size) for injection molding the small diameter portion is used. The diameter portion) may be formed in advance at a predetermined position on the inner periphery of the housing.

  Also, if the housing has a considerable thickness in the radial direction, for example, a ring-shaped member having a small-diameter portion formed separately in advance is fitted into a fitting recess provided on the inner periphery of the housing, so that a predetermined position of the housing is obtained. It is also possible to form a small diameter portion. At this time, it is possible to easily fit the housing by forming a shape in which a part in the circumferential direction is cut out like a C ring shape.

  Moreover, the small diameter part for temporary fixing may be formed with the material with a larger linear expansion coefficient than a housing.

  According to this configuration, at a high temperature, for example, the small diameter portion having a linear expansion coefficient larger than that of the housing is limited by the housing due to the heating temperature rise of the adhesive, and as a result, the housing is deformed so as to be tightened inward. . Accordingly, it is possible to suppress a reduction in the tightening allowance between the small-diameter portion and the bearing sleeve when the adhesive is cured, and to avoid the situation where the already-positioned bearing sleeve is displaced in the axial direction as much as possible.

  Further, the temporary fixing small-diameter portion may be formed by applying an external force to the housing and partially deforming the housing in addition to the above method.

  According to this method, since the inner peripheral surface of the housing can be formed with a constant diameter, processing is easy. Further, since only the inner diameter of the small diameter portion can be adjusted by the magnitude of the external force, it is not necessary to make a significant design change of the housing even when changing the tightening allowance.

  It should be noted that the release of the external force on the housing may be performed at the stage where the total amount of the thrust bearing gaps of both has been set to a predetermined size. Alternatively, the external force applied to the housing may be released when the gap is set to a predetermined size and the adhesive is supplied between the housing and the bearing sleeve and solidified.

  According to this method, the tightening allowance between the temporary fixing small-diameter portion and the bearing sleeve is given as a size obtained by adding the elastic deformation to the plastic deformation of the housing. With the return to the radial side, the inner peripheral surface of the bearing sleeve that is press-fitted into the small-diameter portion also slightly returns to the outer diameter side. Therefore, even if the substantial tightening allowance is increased, the decrease in the inner diameter of the bearing sleeve can be kept small, and a radial bearing gap of an appropriate size can be secured. In the case of using adhesive fixing together, it is possible to effectively prevent displacement of the bearing sleeve in the axial direction during heating by continuously applying external force until the adhesive is solidified.

  In addition, it is also possible to form a small-diameter portion for temporary fixing inside the thin portion by providing a thin portion in the housing and applying an external force to the thin portion. Alternatively, by providing a plurality of thin portions on the housing and applying an external force between these thin portions, a small-diameter portion for temporary fixing can be formed inside the region between the thin portions.

  With any of these methods, the housing can be partially deformed with a smaller load than a housing with a constant thickness, so that the amount of deformation in a portion other than the small-diameter portion is kept as small as possible and the shape accuracy in that portion is kept high. be able to.

  In the hydrodynamic bearing device according to the above description, the housing may constitute a part of a motor bracket, for example.

  Thus, in general, when the housing is formed integrally with the motor bracket, the equipment required for the assembly work of the bearing sleeve is limited and time-consuming as the shape of the housing becomes complicated. However, with the above-described bearing device, the assembly operation and the thrust bearing clearance can be set only by fixing the housing integrated with the motor bracket and reciprocating the bearing sleeve and the shaft member in one direction. Therefore, it is possible to simplify the assembly process of a series of hydrodynamic bearing devices including incorporation into information equipment or the like.

  As described above, according to the present invention, in this type of hydrodynamic bearing device, not only the thrust bearing gaps formed on both sides of the flange portion but also the radial bearing gaps can be set with high accuracy. it can.

  Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. Note that the “up and down” direction in the following description is merely defined for easy understanding of the positional relationship between the components in each drawing, and the installation direction, usage mode, manufacturing method, etc. of the hydrodynamic bearing device, etc. It does not specify. The same applies to other embodiments described later.

  FIG. 1 is a sectional view of a spindle motor for information equipment incorporating a fluid dynamic bearing device 1 according to a first embodiment of the present invention. This spindle motor is used by being incorporated in, for example, an HDD equipped with a magnetic disk. The spindle motor 2 is a non-contact support for the shaft member 2 to which the hub 3 is attached in the radial direction, and a radial gap, for example. And a motor bracket 5 including a stator coil 4a and a rotor magnet 4b opposed to each other. The stator coil 4 a is fixed to the motor bracket 5, and the rotor magnet 4 b is fixed to the hub 3. The housing 7 of the hydrodynamic bearing device 1 is fixed to the inner periphery of the motor bracket 5. Further, as shown in FIG. 1, the hub 3 holds one or a plurality of disks 6 (two in FIG. 1). In the spindle motor configured as described above, when the stator coil 4a is energized, the rotor magnet 4b is rotated by the exciting force generated between the stator coil 4a and the rotor magnet 4b, and is accordingly held by the hub 3. The disc 6 rotates integrally with the shaft member 2.

  FIG. 2 shows the hydrodynamic bearing device 1. The hydrodynamic bearing device 1 mainly includes a housing 7, a bearing sleeve 8 fixed to the inner periphery of the housing 7, and a shaft member 2 that rotates relative to the housing 7 and the bearing sleeve 8. In this embodiment, the seal member 12 is disposed at the opening end of the housing 7.

  The shaft member 2 has a shaft portion 2a and a flange portion 2b provided integrally or separately at the lower end of the shaft portion 2a, and is formed of a metal having a relatively high hardness and high rigidity such as stainless steel, for example. . Further, in the outer peripheral surface of the shaft portion 2a, a relief portion 2c having a smaller diameter than the opposed region is formed in a region that does not face the dynamic pressure grooves 8a1 and 8a2 arrangement region of the bearing sleeve 8 described later in the radial direction.

  The bearing sleeve 8 is formed in a shape that allows the shaft portion 2a to be inserted into the inner periphery thereof, and is formed in a cylindrical shape with a porous body made of sintered metal, for example. In this embodiment, the bearing sleeve 8 is formed in a cylindrical shape with a porous body of sintered metal whose main component is Cu. Of course, the bearing sleeve 8 can be formed of a material other than metal, such as resin or ceramic. In addition to porous materials such as sintered metal, non-porous material (solid material) that does not have internal pores, or a material with a structure that has pores large enough to prevent lubricating oil from entering and exiting. It can also be formed.

A region where a plurality of dynamic pressure grooves are arranged as a radial dynamic pressure generating portion is formed on the entire surface or a partial region of the inner peripheral surface 8 a of the bearing sleeve 8. In this embodiment, as shown in FIG. 3, for example, a plurality of dynamic pressure grooves 8a1 and 8a2 having different inclination angles with respect to the circumferential line are arranged in a herringbone shape, and the plurality of dynamic pressures The grooves 8a1 and 8a2 are partitioned by a partition 8a3 having a smaller diameter than the dynamic pressure grooves 8a1 and 8a2. Moreover, in FIG. 3, the dynamic pressure grooves 8a1 and 8a2 having the above-described arrangement form are formed at two locations separated in the axial direction. Here, in the dynamic pressure groove 8a1, 8a2 arrangement region on the upper side (the seal member 12 side), each dynamic pressure groove 8a1, 8a2 is in the axial direction center m (the axial center of the region between the upper and lower inclined grooves). It is formed asymmetrically in the axial direction, than the dynamic pressure grooves 8a2 arranged regions axial dimension X ₂ of the axial dimension X ₁ of the dynamic pressure grooves 8a1 sequence region located above the axial center m are underneath It is getting bigger.

  Further, in this embodiment, the intermediate region 8a4 located between the two dynamic pressure grooves 8a1 and 8a2 arranged in the inner peripheral surface 8a so as to be separated from each other in the vertical direction has a smooth cylindrical surface shape. . Further, the intermediate region 8a4, the dynamic pressure groove 8a2 on the upper side in FIG. 3 adjacent to the intermediate region 8a4, and the dynamic pressure groove 8a1 on the lower side in FIG. On the same plane. As described above, the shape of the inner peripheral surface 8a follows the dynamic pressure grooves 8a1 and 8a2 by forming the bearing sleeve 8 from a sintered metal and using a so-called spring back on the inner peripheral surface 8a. It is formed by pressing a rod-shaped mold having an outer peripheral surface shape.

  As shown in FIG. 4, for example, as shown in FIG. 4, a region in which a plurality of dynamic pressure grooves 8 b 1 are arranged in a spiral shape is formed on the entire lower surface 8 b of the bearing sleeve 8 or a partial region. This dynamic pressure groove 8b1 arrangement region is opposed to the upper end surface 2b1 of the flange portion 2b in the state of the finished product shown in FIG. 2, and a first thrust bearing portion described later between the upper end surface 2b1 when the shaft member 2 rotates. A thrust bearing gap T1 (first thrust bearing gap) is formed.

  One or more axial grooves 8 c 1 extending in the axial direction are formed on the outer peripheral surface 8 c of the bearing sleeve 8. These axial grooves 8c1 are used for quickly recovering the excess / deficiency state to an appropriate state when the hydrodynamic bearing device 1 is used, and when the excess / deficiency of lubricating oil occurs in the bearing internal space. Play a role.

  The housing 7 is formed in a cylindrical shape and has at least one axial end thereof opened. The inner peripheral surface 7a of the housing 7 is formed with a smaller diameter portion 9 that is smaller in diameter than the inner peripheral surface 7a and that temporarily fixes the bearing sleeve 8 to the housing 7 when a thrust bearing gap described later is set. In this embodiment, a disk-like bottom portion 7 b is integrally formed at the lower end in the axial direction of the housing 7, and closes the lower end in the axial direction of the housing 7. Here, on the entire surface or a partial region of the upper end surface 7b1 of the bottom portion 7b, a region in which a plurality of dynamic pressure grooves are arranged in a spiral shape is formed as a thrust dynamic pressure generating portion, for example, although not shown. This dynamic pressure groove arrangement region is opposed to the lower end surface 2b2 of the flange portion 2b in the state of the finished product shown in FIG. 2, and a second thrust bearing portion T2 described later between the lower end surface 2b2 and the shaft member 2 when rotating. The thrust bearing gap (second thrust bearing gap) is formed. The housing 7 can be formed of various materials such as a metal material such as brass or a resin material, and when the housing 7 is made of metal, an injection molding method such as MIM in addition to plastic processing such as machining or forging. (Both molten metal and powder) can be used.

  The small diameter portion 9 is formed at an intermediate position in the axial direction of the inner periphery of the housing 7. In a state in which the bearing sleeve 8 is fixed at a predetermined axial position on the inner periphery of the housing 7 (to be described later) (position when the thrust bearing gap is set), the dynamic pressure grooves 8a1 and 8a2 of the bearing sleeve 8 are displaced in the axial direction from each other. The bearing sleeve 8 is press-fitted and fixed at a position (not overlapping). Therefore, in the finished product state in FIG. 2, the press-fitting region between the small-diameter portion 9 of the housing 7 and the bearing sleeve 8 is formed at a position that is axially displaced (not overlapping) with the dynamic pressure groove 8 a 1, 8 a 2 arrangement region. Yes.

  In this embodiment, the space between the inner peripheral surface 7a of the housing 7 and the outer peripheral surface 8c of the bearing sleeve 8 excluding the press-fitting region is filled with the adhesive 10, whereby the housing 7 and the bearing sleeve 8 are bonded and fixed. Has been. At this time, the layer thickness of the adhesive 10 (in other words, the bonding gap) is determined by the amount of tightening between the small diameter portion 9 and the bearing sleeve 8 based on the protruding height of the small diameter portion 9 from the inner peripheral surface 7a. Set to the subtracted value.

  As described above, when the fixing between the housing 7 and the bearing sleeve 8 is performed not only by press-fitting but also by adhesion, for example, as shown in FIG. 5, the small diameter portion 9 may be provided intermittently in the circumferential direction. Is possible. Thus, by providing the plurality of small-diameter portions 9 intermittently in the circumferential direction, when setting a thrust bearing gap, which will be described later, between the outer peripheral surface 8c of the bearing sleeve 8 in the temporarily fixed state and the small-diameter A predetermined space 11 is formed at a location adjacent to the portion 9 in the circumferential direction. When the adhesive 10 is supplied from the opening of the housing 7 in a state where the bearing sleeve 8 is temporarily fixed, the predetermined space 11 allows the adhesive to flow from the axial opening side of the small diameter portion toward the closing side. Functions as a road. In other words, the predetermined space 11 has a circumferential width that functions as the flow passage.

  In this embodiment, the sealing member 12 as a sealing means is formed of a metal material or a resin material separately from the housing 7, and the lower end of the sealing member 12 is in contact with the upper end surface 8 d of the bearing sleeve 8. Fixed around the circumference. At this time, as fixing means that can be used, fixing is performed by means such as press-fitting, adhesion, welding, and welding.

  A tapered seal surface 12a is formed on the inner periphery of the seal member 12, and a seal space S is formed between the seal surface 12a and the outer peripheral surface of the shaft portion 2a. Further, the lubricating oil is supplied to the inside of the hydrodynamic bearing device 1 so that the oil level of the lubricating oil is always maintained within the range of the seal space S within a predetermined temperature range (operating temperature range or transport temperature range). The filling amount is adjusted.

  The lubrication operation into the hydrodynamic bearing device 1 having the above-described configuration is performed after the above-described components are assembled, and thereby a bearing including a radial bearing gap, a thrust bearing gap, and further an internal hole of the bearing sleeve 8 is provided. The interior space is filled with lubricating oil. At this time, as a means for supplying the lubricating oil to the bearing internal space, for example, a filling method (vacuum impregnation or the like) performed by immersing the entire hydrodynamic bearing device 1 in the lubricating oil, for example, a seal space S such as dripping oil impregnation is used. It is also possible to employ a method of supplying lubricating oil directly from (a dripping oil impregnation method).

  In the fluid dynamic bearing device 1 having the above-described configuration, the region (the region where the dynamic pressure grooves 8a1 and 8a2 are arranged in the upper and lower portions) of the inner peripheral surface 8a of the bearing sleeve 8 is the outer peripheral surface of the shaft portion 2a and the radial bearing Opposing through a gap. When the shaft member 2 is rotated, the lubricating oil in the radial bearing gap is pushed into the axial center m of the dynamic pressure grooves 8a1 and 8a2, and the pressure rises. The first radial bearing portion R1 and the second radial bearing portion R2 that rotatably support the shaft portion 2a in a non-contact manner are configured by the dynamic pressure action of the dynamic pressure groove.

  Further, the first thrust bearing gap between the upper end surface 2b1 of the flange portion 2b and the lower end surface 8b (thrust dynamic pressure generating portion) of the bearing sleeve 8 facing the flange portion 2b, and the lower end surface 2b2 of the flange portion 2b is opposed to the first thrust bearing clearance. An oil film of lubricating oil is formed in the second thrust bearing gap between the upper end surface (thrust dynamic pressure generating portion) 7b1 of the housing bottom 7b and the dynamic pressure action of each dynamic pressure groove. The pressure of these oil films forms a first thrust bearing portion T1 and a second thrust bearing portion T2 that support the flange portion 2b in a non-contact manner so as to be rotatable in both thrust directions.

  The hydrodynamic bearing device 1 of this embodiment is assembled in the following manner, for example.

  First, as shown in FIG. 6, the shaft portion 2 a is fitted to the inner periphery of the bearing sleeve 8 with a predetermined radial gap, and the shaft member 2 and the bearing sleeve 8 in the fitted state are fitted inside the housing 7. Insert around. Note that the small-diameter portion 19 of the housing 7 at this stage (the stage before the bearing sleeve 8 is inserted into the inner periphery of the housing 7) is less than the small-diameter portion 9 after the bearing sleeve 8 is temporarily fixed. Only a small diameter.

  Next, as shown in FIG. 7, the outer peripheral surface 8c of the bearing sleeve 8 is press-fitted into the small-diameter portion 9 of the housing 7 with a predetermined tightening margin, and the lower end surface 8b of the bearing sleeve 8 is engaged with the upper end surface 2b1 of the flange portion 2b. The bearing sleeve 8 is pushed toward the bottom portion 7b until the lower end surface 2b2 of the flange portion 2b comes into contact with the upper end surface 7b1 of the housing bottom portion 7b. As a result, the bearing sleeve 8 is temporarily fixed to the inner periphery of the housing 7, and the thrust bearing gap formed on both sides of the flange portion 2b is zero (the sizes of the first thrust bearing gap and the second thrust bearing gap are both the same). Zero). The shaft member 2 is first inserted into the inner periphery of the housing 7, and then the bearing sleeve 8 is fitted into the shaft portion 2a and press-fitted into the small diameter portion 9 of the housing 7 to achieve the state shown in FIG. It doesn't matter.

  Next, as shown in FIG. 8, the seal member 12 is introduced to the inner periphery of the upper end of the housing 7, and the seal member 12 is moved to a position where the lower end surface of the seal member 12 contacts the upper end surface 8 d of the bearing sleeve 8. It is introduced into the inner periphery of the upper end of Then, from this state, the shaft member 2 together with the bearing sleeve 8 and the seal member 12 is the housing 7 by a dimension δ corresponding to the total amount of the axial dimension of the first thrust bearing gap and the axial dimension of the second thrust bearing gap. Is moved relatively upward in the axial direction. Thereby, the gap in the thrust direction between the lower end surface 2b2 of the flange portion 2b and the upper end surface 7b1 of the housing bottom portion 7b is set to a predetermined size as the total amount δ of both thrust bearing gaps. The seal member 12 may be introduced to the inner periphery of the upper end of the housing 7 after setting the thrust bearing clearance. When the bearing sleeve 8 is press-fitted (temporarily fixed) to the inner periphery of the housing 7, the seal member 12 is used. You may introduce into the inner periphery of the housing 7.

  In the state shown in FIG. 8, the small-diameter portion 9 is at an axially intermediate position of the bearing sleeve 8, specifically, at a position that is axially displaced (not overlapping) with the dynamic pressure grooves 8 a 1 and 8 a 2 of the bearing sleeve 8. It is press-fitted and fixed to the bearing sleeve 8. Accordingly, when the total amount δ of the thrust bearing gap is set to a predetermined size, the intermediate region 8a4 of the inner peripheral surface 8a of the bearing sleeve is positioned on the inner diameter side of the press-fitted region between the small diameter portion 9 and the bearing sleeve 8. As shown in FIG. 9, the intermediate region 8a4 is reduced to the inner diameter side by a size corresponding to the tightening allowance as compared with that before temporary fixing (from the broken line toward the position indicated by the solid line in FIG. 9). In this case, the radial gap W2 between the intermediate region 8a4 and the outer peripheral surface of the shaft portion 2a is a radial gap W1 (substantially) between the partition portion (hill portion) 8a3 that partitions the dynamic pressure grooves 8a1 and 8a2 and the outer peripheral surface of the shaft portion 2a. It is set so as to be always larger than the equivalent radial bearing clearance.

  In this way, after positioning and fixing the bearing sleeve 8 at a predetermined position in the axial direction of the inner periphery of the housing 7, an adhesive is supplied from the upper opening side of the housing 7, and the inner peripheral surface 7 a of the housing 7 excluding the press-fitting region The gap with the outer peripheral surface 8c of the bearing sleeve 8 is filled with the adhesive. Then, for example, by heating to a predetermined temperature and holding this heating state for a predetermined time, the adhesive is cured, and the housing 7 and the bearing sleeve 8 are bonded and fixed at the filling location. The adhesive can be supplied not only after the gap has been set. For example, all or a part of the adhesive to be applied before press-fitting the bearing sleeve 8 is placed on the inner peripheral surface 7a of the housing 7, thereby press-fitting. It plays a role of supplementing the contamination that has occurred at the front part in the introduction direction.

  According to the above-described method, the components of the hydrodynamic bearing device 1 are actually combined and both thrust bearing gaps are once set to zero. From this state, the bearing sleeve 8 is placed in the axial direction with respect to the housing 7. Since the thrust bearing gap is formed by relative movement by a fixed amount, each component surface of the thrust bearing gap (below the bearing sleeve 8) can be managed only by managing the above axial relative movement amount (= total amount of thrust bearing gap δ). The thrust bearing gap can be accurately formed without being affected by the surface accuracy of the end surface 8b, the upper end surface 7b1 of the housing bottom portion 7b, the both end surfaces 2b1, 2b2) of the flange portion 2b, and the axial dimensional accuracy of the flange portion 2b. Can do.

  Further, since a small-diameter portion 9 for temporary fixing is provided on a part of the inner peripheral surface 7a of the housing 7 and the bearing sleeve 8 is press-fitted and fixed by this small-diameter portion 9, the substantial press-fitting area is reduced. Thus, deformation of the bearing sleeve inner peripheral surface 8a toward the inner diameter side can be suppressed to be small. Further, as described above, the temporary fixing small-diameter portion 9 is finally press-fitted and fixed at a position where the regions (dynamic pressure groove 8a1 and 8a2 arrangement region) that are substantially radial bearing surfaces are axially removed from each other. Therefore, when the bearing sleeve 8 is press-fitted, the intermediate region 8a4 that does not have the dynamic pressure grooves 8a1 and 8a2 in the inner peripheral surface 8a of the bearing sleeve 8 is preferentially deformed toward the inner diameter side. Therefore, the radial bearing gap can be managed with high accuracy by minimizing changes in the inner diameter of the dynamic pressure grooves 8a1 and 8a2 and the partition portion 8a3.

  Further, as in this embodiment, the bearing 7 is formed by filling and fixing all the gaps between the inner peripheral surface 7a of the housing 7 and the outer peripheral surface 8c of the bearing sleeve 8 excluding the press-fitting region with the small diameter portion 9 with an adhesive. It is possible to remove the gap as a space that adversely affects the vibration characteristics. Further, the bonding area between the housing 7 and the bearing sleeve 8 can be made as large as possible, and the fixing strength of the housing 7 and the bearing sleeve 8 combined with the press-fit strength can be further increased. Further, as shown in FIG. 5, the small diameter portion 9 is intermittently provided in the circumferential direction, and the adhesive 10 can flow between the small diameter portions 9 from the axial opening side of the small diameter portion toward the closing side. By forming the flow passage (predetermined space 11), a sufficient amount of the adhesive 10 can be supplied to the axially closed side of the small diameter portion 9 regardless of the supply timing.

  While the first embodiment of the present invention has been described above, the method and the bearing device according to the present invention are not limited to this embodiment, and the configuration can be arbitrarily changed within the scope of the present invention.

  FIG. 10 shows a cross-sectional view of the hydrodynamic bearing device 21 according to the second embodiment. The hydrodynamic bearing device 21 is mainly configured with the hydrodynamic bearing device 1 according to FIG. 2 in that a temporary fixing small-diameter portion 29 is formed separately from the housing 27 and integrated with the housing 27. It is different.

  In this illustrated example, an annular recess 27c for fitting and fixing the annular member 22 having the small diameter portion 29 is formed at a predetermined position in the axial direction of the housing inner peripheral surface 27a, and the annular recess 27c is separately formed in advance. By fitting and fixing the annular member 22, a small-diameter portion 29 for temporary fixing is formed at a predetermined axial position on the inner periphery of the housing 27. A thrust bearing portion (second thrust portion) is formed between the point where the bottom portion 27b is formed integrally with the housing 27 and the upper end surface 27b1 of the bottom portion 27b and the lower end surface 2b2 of the flange portion 2b opposite to the upper end surface 27b1. Since other configurations such as the formation of the bearing portion T2) are substantially the same as those of the first embodiment, the corresponding portions are denoted by the same reference numerals and description thereof is omitted.

  By providing the small-diameter portion 29 in the housing 27 by such a method, the same effect as that obtained by the above-described method can be obtained, and the housing 27 is required as a housing for the hydrodynamic bearing device 21. In addition, the small-diameter portion 29 for temporary fixing can be formed of a material having rigidity suitable for press-fitting temporary fixing with the bearing sleeve 8 and is required for each part. The characteristics can be satisfied easily and at low cost.

  In this case, the small diameter portion 29 for temporary fixing can be formed on the inner periphery of the housing 27 by injection molding. A specific procedure will be described. First, as shown in FIG. 11A, the housing material 127 is formed by roughing, and then, as shown in FIG. An annular member 122 made of resin is formed by injection molding in an annular recess 127c provided on the inner periphery. Finally, the housing material 127 and the annular member 122 are subjected to an appropriate finishing process such as polishing to form a housing 27 as a finished product as shown in FIG. A temporary fixing small-diameter portion 29 having a predetermined fastening margin is formed on the inner periphery.

  According to this method, the dimensional accuracy of the housing material 127 to be injection-molded is not so required, and high dimensional accuracy is not required for the injection mold. Therefore, it is possible to reduce the cost for such processing equipment. In addition, in the case of injection molding, the annular member 22 can be easily formed in the annular recess 27c of the housing 27 without taking any measures such as providing a notch in the annular member 22 formed separately from the housing 27. Can do. Further, in this case, since the annular member 22 having the small diameter portion 29 is formed in the annular recess 27c, it has a high retaining strength even when the bearing sleeve 8 is press-fitted.

  Further, if the small diameter portion 29 is formed of a material having a larger linear expansion coefficient than that of the housing 27 such as resin, for example, when the adhesive 10 is heated and cured, the small diameter portion 29 (annular member having a larger linear expansion coefficient than the housing 27 as the temperature rises). The expansion of 22) toward the outer diameter side is limited by the housing 27, and as a result, the small diameter portion 29 is deformed so as to be tightened inward. As a result, it is possible to suppress a reduction in the fastening allowance between the small diameter portion 29 and the bearing sleeve 8 when the adhesive is cured, and to avoid as much as possible a situation in which the already-positioned bearing sleeve 8 is displaced in the axial direction. In particular, by forming the annular member 22 having a relatively large linear expansion coefficient thicker than the housing 27 as in this embodiment, the above effect can be obtained more effectively.

  FIG. 12 shows a cross-sectional view of a fluid dynamic bearing device 31 according to the second embodiment. The hydrodynamic bearing device 31 is mainly composed of a temporary fixing small-diameter portion 39 formed by applying an external force to the housing 37 and partially deforming the housing 37, as shown in FIG. It differs from the device 1 in configuration.

  In this illustrated example, a partially annular thin portion 37c is provided at an axially intermediate position of the housing 37, and an external force is applied to the thin portion 37c by an appropriate means to temporarily fix the thin portion 37c inside. A small diameter portion 39 is formed. In this case, as shown in FIG. 13A, for example, the small-diameter portion 39 is formed by preparing a housing 37 in which the inner peripheral surface 37a has a constant diameter and a thin portion 37c is provided at a predetermined position in the axial direction. The thin portion 37c is pressed and deformed from the outside of the thin portion 37c of the housing 37 to the inner diameter side over the entire circumference by an appropriate external force applying means 32 (such as a fastening member). By adopting such a method, the small-diameter portion 39 is formed in the inner portion of the thin portion 37c. A thrust bearing portion (second thrust portion) is formed between the point where the bottom portion 37b is formed integrally with the housing 37 and the upper end surface 37b1 of the bottom portion 37b and the lower end surface 2b2 of the flange portion 2b facing the upper end surface 37b1. Since other configurations such as the formation of the bearing portion T2) are substantially the same as those of the first embodiment, the corresponding portions are denoted by the same reference numerals and description thereof is omitted.

  By providing the small-diameter portion 39 in the housing 37 by such a method, the same operation effect as that obtained by the above-described method can be obtained, and the inner peripheral surface 37a of the housing 37 can be formed with a constant diameter. The merit that processing is easy is obtained. Further, since only the inner diameter dimension of the small diameter portion 39 can be adjusted by the magnitude of the external force by the external force applying means 32 or the like, a significant design change of the housing 37 is not performed even when the tightening margin is changed. It will end.

  Further, according to this method, the housing 37 can be partially deformed with a load smaller than that of a housing having a constant thickness. Therefore, the amount of deformation in a portion other than the small-diameter portion 39 can be suppressed as small as possible on the inner peripheral surface 37a. The shape accuracy can be kept high. For example, as shown in FIG. 13 (b), the operational effect is obtained by providing an annular thin portion 37 c in two locations apart in the axial direction of the housing 37, and applying an external force between these thin portions 37 c. It can be obtained in the same manner by forming a small-diameter portion 39 for temporary fixing inside the region between the thin portions 37c and 37c.

  The release of the external force with respect to the housing 37 may be performed when the total amount δ of both thrust bearing gaps has been set to a predetermined size. Alternatively, the external force applied to the housing 37 is released when the total amount δ of the gap is set to a predetermined size and the adhesive 10 is supplied between the housing 37 and the bearing sleeve 8 and solidified. It may be.

  According to this method, the fastening allowance between the temporary fixing small-diameter portion 39 and the bearing sleeve 8 is given by a value obtained by adding the elastic deformation to the plastic deformation of the housing 37. Therefore, after the thrust gap is set, the inner peripheral surface 8a of the bearing sleeve 8 press-fitted into the small diameter portion 39 is slightly returned to the outer diameter side as the small diameter portion 39 returns to the outer diameter side. Therefore, even when the substantial tightening allowance is slightly increased, the ratio of the reduction in the inner diameter of the bearing sleeve 8 can be kept small, and a radial bearing gap of an appropriate size can be secured. In particular, as shown in this embodiment, when bonding is used in combination, by continuously applying an external force until the adhesive 10 is solidified, the axial displacement of the bearing sleeve 8 during heating is effectively reduced. While preventing, high fixation strength between the housing 37 can be obtained.

  Moreover, in the above embodiment (1st-3rd embodiment), as radial bearing part R1, R2 and thrust bearing part T1, T2, the dynamic pressure action of lubricating oil by a herringbone shape or a spiral-shaped dynamic pressure groove is used. However, the present invention is not limited to this.

  For example, as the radial bearing portions R1 and R2, although not shown, a so-called step-like dynamic pressure generating portion in which axial grooves are formed at a plurality of locations in the circumferential direction, or a plurality of circular arc surfaces in the circumferential direction. A so-called multi-arc bearing in which wedge-shaped radial gaps (bearing gaps) are formed between the outer peripheral surfaces of the opposing shaft members 2 may be employed.

  Alternatively, the inner peripheral surface 8a of the bearing sleeve 8 is a perfect circular inner peripheral surface not provided with a dynamic pressure groove or a circular arc surface as a radial dynamic pressure generating portion, and a perfect circular outer peripheral surface facing the inner peripheral surface. Thus, a so-called perfect circle bearing can be configured.

  One or both of the thrust bearing portions T1 and T2 are also not shown in the figure, but a plurality of radial groove-shaped dynamic pressure grooves are provided at predetermined intervals in the circumferential direction in a region serving as a thrust bearing surface. It can also be configured by a step bearing or a corrugated bearing (having a corrugated waveform such as an end face).

  In the above embodiment, the case where the dynamic pressure generating portions are all provided on the fixed side (the bearing sleeve 8 and the bottom portion 7b) has been described. However, part or all of the dynamic pressure generating portion is provided on the rotating side (the shaft portion 2a and the flange). It is also possible to provide it in the part 2b or the like. Specifically, it is possible to provide the above-described dynamic pressure generating portion on one or both of the outer peripheral surface of the shaft member 2 and both end surfaces 2b1, 2b2 of the flange portion 2b.

  Moreover, although the above embodiment demonstrated the case where the bottom part 7b of the housing 7 was formed integrally with the housing 7, this invention is a dynamic pressure which performs the thrust bearing clearance setting of the housing 7 which formed the bottom part 7b separately. The present invention can also be applied to a bearing device. FIG. 14 shows an example thereof. In the hydrodynamic bearing device 41 according to the figure, a bottom portion 47b that closes the lower end in the axial direction of the housing 47 is formed separately from the housing 47, and this bottom portion 47b is formed by an appropriate means ( It is fixed to the housing 47 by bonding, press fitting, welding, or the like. Then, in the state where the bottom 47b is fixed to the housing 47, the above-described thrust bearing gap is set.

  In the illustrated example, the lower end of the housing 47 is formed as a relatively thin caulking portion 47c to secure the pull-out strength of the bottom portion 47b, and the bottom portion 47b is fitted to the lower end of the inner periphery of the housing 47, The case where the bottom part 47b is fixed by caulking by applying caulking to 47c is shown.

  Further, in the above embodiment, the case where the housing 7 (including the housings 27, 37, 47. The same applies hereinafter) and the motor bracket 5 are formed separately and then integrated by appropriate means will be described. However, in the above hydrodynamic bearing device 1, the housing 7 may be integrally formed of the same material as the motor bracket 5, for example. In other words, the housing 7 may constitute a part (inner diameter side) of the motor bracket 5.

  As described above, even if the housing 7 is formed integrally with the motor bracket 5, in the above-described hydrodynamic bearing device 1, the housing integrated with the motor bracket is fixed, and the bearing sleeve 8 and the shaft member 2 are fixed. The assembly operation of these components and the setting of the thrust bearing gap can be performed only by reciprocating in one direction. Therefore, a series of assembly processes of the hydrodynamic bearing device 1 including incorporation into information equipment or the like can be simplified. Needless to say, not only the motor bracket 5 but also a component part of a device into which the hydrodynamic bearing device 1 is to be incorporated, and a part that directly mounts or fixes the housing 7, as with the motor bracket 5, is integrated with the housing 7. It is possible to

  In the above embodiment, after the bearing sleeve 8 is pushed to a position where the bearing sleeve 8 abuts against the flange portion 2 b and the flange portion 2 b abuts against the bottom portion 7 b of the housing 7, the bearing sleeve 8 is moved from this abutting position. The bearing sleeve 8 is moved to the final fixed position with respect to the housing 7 by relatively moving in a direction away from the bottom 7b. However, the moving mode is not necessarily limited thereto. As long as a mode is adopted in which the bearing sleeve is moved from the state of being press-fitted into the temporary fixing small-diameter portions 9, 29, 39 to the final fixed position, it is possible to adopt any movement mode (movement path). .

  Further, in the above embodiment, the lubricating oil is exemplified as a fluid for filling the inside of the hydrodynamic bearing device 1 and forming a fluid film in the radial bearing gap or the thrust bearing gap. A fluid that can be formed, for example, a gas such as air, a fluid lubricant such as a magnetic fluid, or a lubricating grease can also be used.

1 is a cross-sectional view including a spindle motor of a spindle motor provided with a fluid dynamic bearing device according to a first embodiment of the present invention. It is a shaft-containing sectional view of the fluid dynamic bearing device concerning a 1st embodiment. It is a shaft-containing sectional view of a bearing sleeve. It is the top view which looked at the bearing sleeve shown in FIG. 3 from the lower end surface side. It is an axial orthogonal cross section in the small diameter part of a fluid dynamic bearing device. It is a figure which shows an example of the setting process of a thrust bearing clearance conceptually, Comprising: It is a shaft-containing sectional view of the bearing sleeve and housing before press-fitting mutually. It is a figure which shows notionally an example of the setting process of a thrust bearing clearance, Comprising: It is a shaft-containing sectional view of the bearing sleeve and housing of a state in which the bearing sleeve is press-fitted to a position where the thrust bearing clearance becomes zero. It is a figure which shows an example of the setting process of a thrust bearing clearance conceptually, Comprising: It is an axial cross-sectional view of the bearing sleeve and housing in the state in which the thrust bearing clearance was set. It is an expanded sectional view of a radial bearing gap periphery in a state where a thrust bearing gap is set. It is a shaft-containing sectional view of a fluid dynamic bearing device concerning a 2nd embodiment of the present invention. FIG. 9 conceptually shows a manufacturing process of a temporary fixing small-diameter portion according to the second embodiment, where (a) is a cross-sectional view including a shaft when a housing material is formed by roughing, and (b) is an annular shape by injection molding. A shaft-containing cross-sectional view at a stage where the member is formed in the annular recess of the housing material, (c) is a shaft-containing cross-sectional view of the housing and the small-diameter portion finished to a predetermined size by finishing. It is a shaft-containing sectional view of a fluid dynamic bearing device concerning a 3rd embodiment of the present invention. The manufacturing process of the small diameter part for temporary fixation which concerns on 3rd Embodiment is shown notionally, (a) forms the small diameter part by providing external force to the thin part partially provided in the housing. (B) is an axial cross-sectional view showing a form in which a small-diameter portion is formed by providing an external force to an area between the thin-walled portions and providing an external force to a region between the thin-walled portions. is there. It is a shaft-containing sectional view showing an example of a hydrodynamic bearing device provided with a housing having a bottom part as a separate body.

Explanation of symbols

1, 21, 31, 41 Hydrodynamic bearing device 2 Shaft member 2a Shaft portion 2b Flange portion 5 Motor bracket 7, 27, 37, 47 Housing 7a, 27a, 37a, 47a Inner peripheral surface 7b, 27b, 37b, 47b Bottom portion 7b1 27b1, 37b1, 47b1 Upper end surface 8 Bearing sleeve 8a Inner peripheral surface 8a1, 8a2, 8b1 Dynamic pressure groove 8a4 Intermediate region 8b Lower end surface 8c Outer peripheral surface 9, 29, 39 Small diameter portion 10 Adhesive 11 Space (flow passage)
12 Seal member 22 Annular member 27c Annular recess 32 External force applying means 37c Thin portion 47c Clamping portion 127 Housing material S Seal space R1, R2 Radial bearing portion T1, T2 Thrust bearing portion δ Total amount of thrust bearing clearance

Claims (12)

A shaft member having a shaft portion and a flange portion, a bearing sleeve having the shaft portion inserted into the inner periphery, a housing having a bottom portion closing one end in the axial direction, and the bearing sleeve fixed to the inner periphery, and facing each other in the axial direction Formed between the first thrust bearing gap formed between one end surface of the flange portion and the one end surface of the bearing sleeve, and the other end surface of the flange portion facing each other in the axial direction and one end surface of the bottom portion of the housing. And a second thrust bearing gap, wherein the first and second thrust bearing gaps are each set to a predetermined size,
The bearing sleeve is fixed to the housing by two types of fixing means. One fixing means is composed of a small-diameter portion for temporary fixing provided on the inner periphery of the housing. The small-diameter portion houses the bearing sleeve by press-fitting. A hydrodynamic bearing device characterized by being a part for being temporarily fixed to a shaft.   2. The hydrodynamic bearing device according to claim 1, wherein the press-fitting region between the temporary fixing small-diameter portion and the bearing sleeve is formed at a position axially displaced from a radial bearing surface provided on the inner periphery of the bearing sleeve. .   2. The hydrodynamic bearing device according to claim 1, wherein a gap between the inner peripheral surface of the housing and the outer peripheral surface of the bearing sleeve is filled with an adhesive, thereby constituting the other fixing means.   The hydrodynamic bearing device according to claim 3, wherein the temporary fixing small-diameter portion is provided with a flow passage through which an adhesive can flow from the axial opening side to the closing side of the small-diameter portion.   The hydrodynamic bearing device according to claim 1, wherein the temporary fixing small-diameter portion is formed separately from the housing.   The hydrodynamic bearing device according to claim 5, wherein the temporary fixing small-diameter portion is formed of a material having a larger linear expansion coefficient than the housing.   The hydrodynamic bearing device according to claim 1, wherein the temporary fixing small-diameter portion is formed by applying an external force to the housing to partially deform the housing.   The hydrodynamic bearing device according to claim 1, wherein the housing constitutes a part of the motor bracket. A shaft member having a shaft portion and a flange portion, a bearing sleeve having the shaft portion inserted into the inner periphery, a housing having a bottom portion closing one end in the axial direction, and the bearing sleeve fixed to the inner periphery, and facing each other in the axial direction Formed between the first thrust bearing gap formed between one end surface of the flange portion and the one end surface of the bearing sleeve, and the other end surface of the flange portion facing each other in the axial direction and one end surface of the bottom portion of the housing. In the manufacturing method of the hydrodynamic bearing device provided with the second thrust bearing gap,
A small-diameter portion for temporary fixing is provided on the inner periphery of the housing, and a bearing sleeve is press-fitted into the small-diameter portion, and the bearing sleeve in a press-fit state is set so that the total amount of the first and second thrust bearing gaps is set to a predetermined size. A method for manufacturing a hydrodynamic bearing device, wherein the hydrodynamic bearing device is moved to a fixed position with respect to a housing.   The bearing sleeve is brought into contact with the flange portion and the flange portion is brought into contact with the bottom portion of the housing, and then the bearing sleeve is moved in a direction away from the bottom portion while maintaining the press-fitted state. The method of manufacturing a hydrodynamic bearing device according to claim 9.   With the total amount of both thrust bearing gaps set to a predetermined size, the small-diameter portion is arranged such that the radial bearing surface and the small-diameter portion provided on the inner periphery of the bearing sleeve are offset from each other in the axial direction. The method for manufacturing a hydrodynamic bearing device according to claim 9 or 10, wherein the step is formed at a predetermined position of the housing.   The hydrodynamic bearing device according to claim 9 or 10, wherein a gap between the inner peripheral surface of the housing and the outer peripheral surface of the bearing sleeve is filled with an adhesive, and the adhesive is solidified to bond and fix the bearing sleeve to the housing. Production method.

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