JP2010096202A - Fluid bearing device and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fluid bearing device reduced in cost for surely preventing the leakage of lubricating oil. <P>SOLUTION: The fluid bearing device 1 includes a bearing member 10 composed of a housing 7 and a bearing sleeve 8 fixed to the inner periphery thereof, a shaft member 2 inserted into the inner periphery of the bearing sleeve 8, and a seal member 9 arranged in an opening portion of the housing 7. Between the seal member 9 and the shaft member 2, and between the seal member 9 and the housing 7, first and second seal spaces S1, S2 are formed, respectively. The seal member 9 is a resin-injection molded product from which a skin layer is removed by deburring work after molding. Plating coats 13 are formed on an inner peripheral face 9a2 and an outer peripheral face 9b1 which function as seal faces 12 forming the seal spaces S1, S2, respectively, out of the surface of the seal member 9. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

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

  The hydrodynamic bearing device rotatably supports a shaft to be supported by an oil film formed in a bearing gap. This hydrodynamic bearing device has characteristics such as high-speed rotation, high rotation accuracy, and low noise. In recent years, the hydrodynamic bearing device has been utilized as a motor bearing device for motors mounted on various electrical devices including information devices. More specifically, spindle motors for magnetic disk devices such as HDD, optical disk devices such as CD-ROM, CD-R / RW, DVD-ROM / RAM, etc., polygon scanner motors for laser beam printers (LBP), PCs It is suitably used as a motor bearing device such as a fan motor.

  For example, Japanese Patent Laid-Open No. 2003-239974 (Patent Document 1) includes a housing having a housing and a bearing sleeve fixed to the inner periphery thereof, and a shaft member having one end opened and a shaft member inserted into the inner periphery of the bearing member. And a radial bearing gap formed facing the outer peripheral surface of the shaft member and formed with an oil film for supporting the shaft member in the radial direction, and a seal member disposed in the opening of the bearing member A bearing device is disclosed. The seal member forms a seal space having an oil surface (gas-liquid interface) with the counterpart member (here, the shaft member), thereby preventing leakage of the lubricating oil filled in the internal space of the bearing member. The seal member can be formed of a metal material or a resin material. However, in recent years, the seal member is often an injection-molded product of resin for the purpose of reducing the weight of the hydrodynamic bearing device and reducing the cost.

A burr may be formed in the seal member that is an injection molded product of resin, and the burr may fall off and become contaminated if the seal member is used while the burr is left as it is. There is a risk of functional degradation. Therefore, deburring is generally performed before the resin seal member is disposed in the opening of the bearing member.
JP 2003-239974 A

  Deburring can be performed to selectively remove burrs. However, it is usually performed in a batch process such as barreling because manual processing is required, resulting in high costs. It is. However, although barrel processing has the merit that burrs can be removed reliably and easily, the so-called skin layer on the surface of the molded product is also removed at the same time. The material is exposed on the surface. If the filler is exposed to a surface (seal surface) that forms a seal space with the mating member, the lubricant may be transmitted to the exposed filler and leak out of the bearing.

  An object of the present invention is to reliably prevent leakage of lubricating oil in this type of hydrodynamic bearing device.

  As a first configuration for solving the above-described problem, in the present invention, a bearing member having at least one end opened, a shaft member inserted into the inner periphery of the bearing member, and an outer peripheral surface of the shaft member are formed. A hydrodynamic bearing device comprising: a radial bearing gap in which an oil film for supporting the shaft member in the radial direction is formed; and a seal member disposed in the opening of the bearing member and forming a seal space communicating with the radial bearing gap The hydrodynamic bearing device is characterized in that the sealing member is an injection molded product of the resin from which the skin layer has been removed, and a coating is formed on at least the sealing surface of the sealing member facing the sealing space.

  If it is the said 1st structure, even if it is a case where a sealing member is injection-molded with the resin material containing a filler and a filler is exposed to the surface by removing a skin layer, the sealing surface which faces seal space In this case, a coating is formed, and the exposed filler can be covered with the coating. Therefore, a situation in which lubricating oil leaks to the outside through the exposed filler is effectively prevented, and high sealing performance is achieved. Can be secured. Further, since the seal member is made of resin, the cost of the hydrodynamic bearing device can be reduced.

  In the first configuration, the coating film formed on at least the sealing surface of the sealing member is not particularly limited as long as it can cover the filler exposed on the surface with the removal of the skin layer. It may be a plating film formed by plating or an oil repellent film formed by solidifying an oil repellent. However, if an oil-repellent film is formed on the seal surface that forms the seal space in the surface of the seal member, there is a possibility that the lubricating oil leakage may be promoted. Such a problem can be solved by applying UV treatment to the oil repellent film formed on the seal surface. That is, if the oil repellent film is subjected to UV treatment, the oil repellent effect of the oil repellent film can be lost, so that the lubricating oil leaks through the filler and the oil repellent film is formed on the seal surface. The problem of lubricating oil leakage can be reliably prevented, which is desirable.

  Further, as a second configuration for solving the above problems, in the present invention, the bearing member having at least one end opened, the shaft member inserted in the inner periphery of the bearing member, and the outer peripheral surface of the shaft member are faced. A fluid comprising: a radial bearing gap formed to form an oil film for supporting the shaft member in the radial direction; and a seal member disposed in an opening of the bearing member and forming a seal space communicating with the radial bearing gap. In the bearing device, the seal member is a resin injection-molded product from which the skin layer is removed, and at least the seal surface facing the seal space of the seal member is subjected to a filler removing process. Providing equipment.

  With this configuration, even when the sealing member is injection-molded with a resin material including a filler and the filler is exposed on the surface by removing the skin layer, the filler is applied to the sealing surface facing the seal space. Therefore, a situation in which the lubricating oil leaks to the outside through the exposed filler is effectively prevented. Moreover, since the sealing member is made of resin as in the case of employing the first configuration, the cost of the hydrodynamic bearing device can be reduced. The method for removing the filler exposed on the surface is not particularly limited. For example, so-called aero wrap is preferred, in which lapping, in particular, polishing with a frictional force by which a medium having humidity and elasticity slides is used.

  Further, as a third configuration for solving the above-described problem, a bearing member having at least one end opened, a shaft member inserted in the inner periphery of the bearing member, and an outer peripheral surface of the shaft member are formed. In a hydrodynamic bearing device comprising: a radial bearing gap in which an oil film for supporting a member in the radial direction is formed; and a seal member that is disposed in an opening of the bearing member and forms a seal space that communicates with the radial bearing gap. A hydrodynamic bearing device is provided in which the seal member is an injection molded product of neat resin. The “neat resin” here means a resin material that does not contain various fillers such as glass fiber and carbon fiber, that is, a resin material made only of a base resin.

  In this way, if the seal member is an injection molded product of NEETRESIN, the filler will not be exposed on the seal surface even if deburring is performed after molding, and therefore the lubricant leaks due to the exposure of the filler. Does not occur. Therefore, there is no need to form a coating on the sealing surface as described above, or to remove the filler exposed on the sealing surface, and the hydrodynamic bearing device that can reliably prevent the leakage of lubricating oil can be further reduced in cost. can get. A seal member injection molded with a knee resin is inferior in mechanical properties, such as strength, to a seal member injection molded with a resin containing various fillers. It is a member provided mainly for the purpose of forming a seal space, and it is not necessary to satisfy the strength required for a bearing member, for example. Therefore, even if the above configuration is adopted, no particular problem occurs in actual use.

  In order to solve the above problems, in the present invention, a bearing member having at least one open end, a shaft member inserted into the inner periphery of the bearing member, and an outer peripheral surface of the shaft member are formed. In a method of manufacturing a hydrodynamic bearing device, comprising: a radial bearing gap in which an oil film for supporting in the radial direction is formed; and a seal member disposed in an opening of the bearing member and forming a seal space communicating with the radial bearing gap. A method of manufacturing a hydrodynamic bearing device, comprising: removing a skin layer from a resin injection molded seal member, and forming a coating on at least a seal surface facing the seal space of the seal member. To do.

  In the above manufacturing method, the coating film can be an oil repellent film formed by solidifying an oil repellent agent, and can further include a step of performing UV treatment on the oil repellent film formed on the seal surface. .

  Moreover, the 2nd manufacturing method based on this invention made | formed in order to solve the said subject, after removing the skin layer of the sealing member injection-molded with resin, among the sealing members, the sealing surface which faces at least sealing space It is characterized in that the filler is removed.

  As described above, according to the present invention, in this type of hydrodynamic bearing device, lubricating oil leakage can be reliably prevented.

  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. This spindle motor is used in a disk drive device such as an HDD, and has a hydrodynamic bearing device 1 that rotatably supports a shaft member 2, a disk hub 3 fixed to the shaft member 2, and a gap in the radial direction, for example. And a stator coil 4 and a rotor magnet 5, and a bracket 6. The stator coil 4 is attached to the outer periphery of the bracket 6, and the rotor magnet 5 is attached to the inner periphery of the disk hub 3. The housing 7 (bearing member 10) of the hydrodynamic bearing device 1 is attached to the inner periphery of the bracket 6. One or a plurality of disks D such as magnetic disks (two in the illustrated example) are held on the disk hub 3. 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, and accordingly, the disk hub 3 and the disk D held by the disk hub 3 are shaft members. 2 and rotate together.

  FIG. 2 shows a first embodiment of a hydrodynamic bearing device 1 according to the present invention. The hydrodynamic bearing device 1 is disposed in a bearing member 10 having an open end, a shaft member 2 inserted into the inner periphery of the bearing member 10 and rotating relative to the bearing member 10, and an opening of the bearing member 10. The seal member 9 is provided as a main constituent member. In the present embodiment, the bearing member 10 includes a housing 7 and a bearing sleeve 8 fixed to the inner periphery of the housing 7. In the following description, for the sake of convenience, the side where the seal member 9 is provided will be described as the upper side, and the opposite side in the axial direction will be described as the lower side.

  The shaft member 2 is formed of, for example, a metal material such as stainless steel, and includes a shaft portion 2a and a flange portion 2b provided integrally or separately at the lower end of the shaft portion 2a. The shaft member 2 may be formed of a metal material as a whole, or may be a metal-resin hybrid structure in which, for example, the entire flange portion 2b or a part thereof (for example, both end surfaces) is formed of resin.

  The bearing sleeve 8 is formed in a cylindrical shape with a porous body made of a sintered metal, in particular, a porous body of a sintered metal mainly composed of copper. The bearing sleeve 8 can be formed of a soft metal such as brass in addition to the sintered metal.

  On the inner peripheral surface 8a of the bearing sleeve 8, cylindrical regions serving as the radial bearing surfaces of the first and second radial bearing portions R1 and R2 are provided at two axial positions apart from each other. As shown in FIG. 3A, radial dynamic pressure generating portions A1 and A2 each formed by arranging a plurality of dynamic pressure grooves Aa1 and Aa2 in a herringbone shape are formed. The upper dynamic pressure groove Aa1 is formed axially asymmetric with respect to the axial center m (the axial center of the upper and lower inclined groove regions), and the axial dimension X1 of the upper region is lower than the axial center m. It is larger than the axial dimension X2 of the side region. On the other hand, the lower dynamic pressure groove 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. The radial dynamic pressure generating portions A1 and A2 can also be formed on the outer peripheral surface 2a1 of the shaft portion 2a opposed in the radial direction, and a plurality of dynamic pressure grooves may be arranged in a spiral shape or the like. good.

  The lower end surface 8b of the bearing sleeve 8 is provided with an annular region serving as a thrust bearing surface of the first thrust bearing portion T1, and the region includes a plurality of dynamic pressure grooves Ba as shown in FIG. A thrust dynamic pressure generating portion B is formed by arranging them in a spiral shape. The thrust dynamic pressure generating portion B can also be formed on the upper end surface 2b1 of the flange portion 2b facing in the axial direction, and a plurality of dynamic pressure grooves may be arranged in a herringbone shape or the like.

  In the outer peripheral surface of the bearing sleeve 8, one or a plurality of axial grooves 8d1 opened at both end surfaces are formed. In this embodiment, as shown in FIG. Has been.

  The housing 7 is made of a metal material or a resin material, and is formed in a bottomed cylindrical shape (cup shape) integrally including a cylindrical side portion and a disc-shaped bottom portion 7c that closes a lower end opening of the side portion. The side portion is composed of a small diameter portion 7a and a large diameter portion 7b disposed above the small diameter portion 7a. The inner peripheral surface 7a1 of the small diameter portion 7a is smaller in diameter than the inner peripheral surface 7b1 of the large diameter portion 7b, and The outer peripheral surface of the small diameter portion 7a has a smaller diameter than the outer peripheral surface of the large diameter portion 7b. The inner peripheral surface 7a1 of the small diameter portion 7a and the inner peripheral surface 7b1 of the large diameter portion 7b are connected by a step surface 7e extending in a direction orthogonal to the axis. An oil repellent film 14 (indicated by a wavy line in the figure) is formed on the upper end surface 7b2 of the large diameter portion 7b.

  An annular region serving as a thrust bearing surface of the second thrust bearing portion T2 is provided on the inner bottom surface 7c1 of the housing 7 (the upper end surface of the bottom portion 7c). A thrust dynamic pressure generating portion formed by arranging the dynamic pressure grooves in a spiral shape is formed. This thrust dynamic pressure generating portion is molded simultaneously with the injection molding of the housing 7. The thrust dynamic pressure generating portion can also be formed on the lower end surface 2b2 of the flange portion 2b facing in the axial direction, and a plurality of dynamic pressure grooves may be arranged in a spiral shape or the like.

  The seal member 9 is made of a resin material in which polyphenylene sulfide (PPS) is used as a base resin and an appropriate amount of a filler such as glass fiber is blended therein, and a disc-shaped first seal portion 9a and an outer portion of the first seal portion 9a. It is injection-molded into an inverted L-shaped cross section integrally having a cylindrical second seal portion 9b extending downward from the radial end. The seal member 9 is fixed to the outer periphery of the upper end of the bearing sleeve 8, and in the fixed state, an axial gap 11 is formed between the lower end surface 9 b 3 of the second seal portion 9 b and the step surface 7 e of the housing 7. One or a plurality of radial grooves 9a11 extending radially are formed on the lower end surface 9a1 of the first seal portion 9a, and the radial grooves 9a11 are molded at the same time as the seal member 9 is injection molded. . Thus, the cost of the hydrodynamic bearing device 1 can be reduced by using the seal member 9 as a resin injection-shaped product.

  The inner peripheral surface 9a2 of the first seal portion 9a forms a first seal space S1 having a predetermined volume with the outer peripheral surface 2a1 of the shaft portion 2a, and the outer peripheral surface 9b1 of the second seal portion 9b is the housing 7 A second seal space S2 having a predetermined volume is formed between the inner diameter surface 7b1 of the large-diameter portion 7b. That is, in this embodiment, the inner peripheral surface 9a2 of the first seal portion 9a and the outer peripheral surface 9b1 of the second seal portion 9b correspond to the seal surface 12 referred to in the present invention. Both the inner peripheral surface 9a2 of the first seal portion 9a and the inner peripheral surface 7b1 of the large-diameter portion 7b of the housing 7 are formed in a tapered surface shape whose inner diameter dimension is gradually reduced downward, and accordingly, Both seal spaces S1 and S2 have a tapered shape with a diameter gradually reduced downward. The seal spaces S1 and S2 have a buffer function for absorbing the volume change amount accompanying the temperature change of the lubricating oil filled in the internal space of the housing 7, and the oil level of the lubricating oil is within the assumed temperature change range. It is always held in the seal spaces S1 and S2.

  The seal member 9 is obtained by removing the skin layer on the surface generated by injection molding, and the oil repellent film 14 is formed on the upper end surface 9a3 of the first seal portion 9a. A plating film 13 is formed on the inner peripheral surface 9a2 of the first seal portion 9a and the outer peripheral surface 9b3 of the second seal portion 9b, which function as the seal surface 12 that forms the seal spaces S1 and S2. 12 and 12 are mirror-finished.

  The sealing member 9 having the above configuration is temporarily formed through an injection molding process, a deburring process, and a plating film forming process in this order, and is then repelled on the upper end surface 9a3 of the first seal portion 9a when it is assembled to the bearing sleeve 8. It is completed by forming the oil film 14. The steps after the injection molding process will be described in detail. First, in the deburring process, the molded product (seal member 9) obtained by injection molding is formed at a portion corresponding to the abutting surface of the molding die. The burr is removed. The removal of burrs is performed by batch processing such as barrel processing in consideration of cost, and along with this barrel processing, the burrs are removed and simultaneously the skin layer generated on the surface of the molded product is removed.

  The surface of the seal member 9 from which burrs (skin layers) have been removed in the deburring step is in a state where the filler contained in the forming material of the seal member 9 is exposed. In the plating film forming step, the plating film 13 is formed on the surface of the sealing member 9 to cover the filler exposed on the surface. In the present embodiment, the plating film 13 is formed only on the inner peripheral surface 9a2 of the first seal portion 9a that functions as the seal surface 12 and the outer peripheral surface 9b3 of the second seal portion 9b (see the black portions in FIG. 2). ). If the filler is exposed on the seal surface 12 forming the seal space, the lubricating oil may leak through the exposed filler, while the filler is exposed on a surface other than the seal surface 12. This is because there is no particular problem in bearing performance. If there is no problem in terms of cost or the like, the plating film 13 may be formed in addition to the seal surface 12.

  As described above, the seal member 9 in which the plating film 13 is formed on the inner peripheral surface 9a2 of the first seal portion 9a and the outer peripheral surface 9b3 (seal surface 12) of the second seal portion 9b includes the housing 7 and the bearing sleeve 8. In the assembly in which the shaft member 2 is assembled, the bearing sleeve 8 is fixed to the outer periphery of the upper end. After being fixed, the oil repellent film 14 is formed on the upper end surface 9a3 of the first seal portion 9a of the seal member 9 and the upper end surface 7b2 of the large diameter portion 7b of the housing 7. The oil repellent film 14 is formed by applying and solidifying a known oil repellent such as fluorine or silicone to the upper end surface 9a3 of the first seal portion 9a and the upper end surface 7b2 of the housing 7. Although illustration is omitted, the oil repellent film 14 may be formed in a region adjacent to the first seal space S1 in the outer peripheral surface 2a1 of the shaft portion 2a. The hydrodynamic bearing device 1 shown in FIG. 2 is completed by filling the internal space of the housing 7 (bearing member 10) with lubricating oil as a lubricating fluid including the internal pores of the bearing sleeve 8.

  In the above description, the oil repellent film 14 is formed on the upper end surface 9a3 of the seal member 9 (first seal portion 9a) after the seal member 9 is assembled to the bearing sleeve 8. However, the oil repellent film 14 is formed on the upper end surface 9a3 in advance. The sealed member 9 may be fixed to the bearing sleeve 8. However, in this case, when the seal member 9 is assembled to the bearing sleeve 8, the oil repellent film 14 formed on the upper end surface 9a3 in advance by pressing the upper end surface 9a3 of the seal member 9 with a jig or the like is not peeled off or damaged. It is important to do. This is to prevent the peeled oil-repellent film 14 from dropping into the bearing and causing contamination. Such a situation is prevented by, for example, forming the oil repellent film 14 intermittently in the radial direction on the upper end surface 9a3 of the seal member 9 and assembling the seal member 9 so that the intermittent portion is pressed with a jig or the like. Is possible.

  In the hydrodynamic bearing device 1 having the above-described configuration, when the shaft member 2 rotates, the upper and lower two regions serving as the radial bearing surface of the inner peripheral surface 8a of the bearing sleeve 8 are different from the outer peripheral surface 2a1 of the shaft portion 2a. Opposing through the bearing gap. As the shaft member 2 rotates, the oil film formed in the radial bearing gaps has its oil film rigidity increased by the dynamic pressure action of the dynamic pressure grooves Aa1 and Aa2, and the shaft member 2 can rotate in the radial direction by this pressure. Is supported in a non-contact manner. As a result, radial bearing portions R1 and R2 that support the shaft member 2 in a non-contact manner so as to be rotatable in the radial direction are spaced apart at two locations in the axial direction.

  At the same time, between the annular region serving as the thrust bearing surface of the lower end surface 8b of the bearing sleeve 8 and the upper end surface 2b1 of the flange portion 2b, and the annular region serving as the thrust bearing surface of the inner bottom surface 7c1 of the housing 7 First and second thrust bearing gaps are respectively formed between the lower end surface 2b2 of the flange portion 2b. As the shaft member 2 rotates, the oil film formed in the thrust bearing gaps has its oil film rigidity increased by the dynamic pressure action of the dynamic pressure groove, and the shaft member 2 can be rotated in both thrust directions by this pressure. Touch supported. As a result, a first thrust bearing portion T1 that supports the shaft member 2 in a non-contact manner so as to be rotatable in one thrust direction and a second thrust bearing portion T2 that supports the shaft member 2 in a non-contact manner so as to be rotatable in the other direction of the thrust are formed. Is done.

  Further, as described above, the upper dynamic pressure groove Aa1 has an axial dimension X1 in the upper region that is larger than the axial dimension X2 in the lower region than the axial center m. The pulling force of the lubricating oil by the dynamic pressure groove Aa1 is relatively larger in the upper region than in the lower region. Due to the differential pressure of the pull-in force, the lubricating oil filled in the gap between the inner peripheral surface 8a of the bearing sleeve 8 and the outer peripheral surface 2a1 of the shaft portion 2a flows downward, and the first thrust bearing portion T1 The first radial bearing portion R1 is circulated through the first thrust bearing gap → the fluid passage formed by the axial groove 8d1 of the bearing sleeve 8 → the fluid passage formed by the radial groove 9a11 of the first seal portion 9a. It is pulled back into the radial bearing gap.

  By adopting such a configuration, the pressure balance of the lubricating oil is maintained, and at the same time, the generation of bubbles accompanying the generation of local negative pressure, the occurrence of lubricant leakage and vibration due to the generation of bubbles, etc. The problem can be solved. When the first seal space S1 communicates with the circulation path, and the second seal space S2 communicates with the axial clearance 11, the bubbles are mixed into the lubricating oil for some reason. However, when the bubbles circulate with the lubricating oil, the air is discharged from the oil surface (gas-liquid interface) of the lubricating oil in the seal spaces S1 and S2 to the outside air. Therefore, adverse effects due to bubbles can be prevented more effectively.

  Further, as described above, since the first and second seal spaces S1, S2 have a tapered shape that gradually decreases toward the inside of the housing 7, the lubricating oil in both the seal spaces S1, S2 is reduced. It is drawn in the direction in which the gap width is narrowed by the drawing action by the capillary force, that is, toward the inside of the housing 7.

  In the present embodiment, as described above, the seal member 9 is injection-molded with a resin material including a filler, and after injection molding, removal of burrs formed along with injection molding (more specifically, burrs are removed). It is assumed that barrel processing was performed for the purpose of preventing contamination due to dropping off. Further, in the barrel processing, since the burrs are removed and the skin layer generated on the surface of the molded product is also removed, various fillers contained in the resin material for molding the seal member 9 are exposed on the surface. It becomes a state. If the seal member 9 is assembled to the bearing sleeve 8 while this state is left as it is, the lubricating oil filled in the bearing is transmitted through the filler exposed on the seal surfaces 12 and 12 forming the seal spaces S1 and S2. However, since the exposed filler is coated by forming the plating film 13 on both the sealing surfaces 12 and 12, such a situation is effectively prevented.

  Further, since the oil repellent film 14 is formed on the upper end surface 9a3 of the seal member 9 and the upper end surface 7b2 of the housing 7 adjacent to both the seal spaces S1 and S2, the lubricating oil leakage is further effectively prevented. From the above configuration, lubricating oil leakage from the inside of the housing 7 (bearing member 10) is effectively prevented.

  Although one embodiment of the hydrodynamic bearing device 1 to which the configuration of the present invention is applied has been described above, the present invention is not limited to the hydrodynamic bearing device 1 having the structure shown in FIG. Hereinafter, other embodiments of the hydrodynamic bearing device 1 to which the present invention is applied will be described. However, substantially the same configurations as those described above are denoted by common reference numerals, and redundant description is omitted.

  FIG. 4 shows a hydrodynamic bearing device 1 according to a second embodiment of the present invention. The hydrodynamic bearing device 1 shown in the figure mainly has a seal member 9 formed in a ring shape and is fixed to the inner periphery of the upper end of the housing 7, and an inner peripheral surface 9 a 2 of the seal member 9 and a shaft portion opposed thereto The point that a single seal space S is formed between the outer peripheral surface 2a1 of 2a, the point that the lower end opening of the housing 7 is closed by a separate lid member 19, and the second thrust bearing portion T2 is 2 is different from the hydrodynamic bearing device 1 shown in FIG. 2 in that it is formed between the upper end surface 19a and the lower end surface 2b2 of the flange portion 2b. Also in this embodiment, the seal member 9 is a resin injection-molded product from which the skin layer is removed (deburring is performed after injection molding by barrel processing or the like), and among the surfaces of the seal member 9 The plating film 13 is formed on the inner peripheral surface 9a2 that functions as at least the seal surface 12 that forms the seal space S. An oil repellent film 14 is formed on the upper end surface of the seal member 9 adjacent to the seal space S.

  FIG. 5 shows a hydrodynamic bearing device 1 according to a third embodiment of the present invention. The hydrodynamic bearing device 1 shown in FIG. 1 is mainly provided with ring-shaped first and second seal members 29 and 30 at two locations separated in the axial direction of the shaft portion 2 a, and the outer peripheral surface of the first seal member 29. A first seal space S1 is formed between 29b and the inner peripheral surface of the housing 7, and a second seal space S2 is formed between the outer peripheral surface 30b of the second seal member 30 and the inner peripheral surface of the housing 7. The first thrust bearing portion T1 is formed between the lower end surface 29a of the first seal member 29 and the upper end surface 8c of the bearing sleeve 8, and the upper end surface 30a of the second seal member 30. 2 is different from the hydrodynamic bearing device 1 shown in FIG. 2 in that the second thrust bearing portion T2 is formed between the bearing sleeve 8 and the lower end surface 8b. Also in this embodiment, the seal members 29 and 30 are resin injection molded products from which the skin layer is removed, and among the surfaces of the seal members 29 and 30, the seal surfaces that form at least the seal spaces S1 and S2 A plating film 13 is formed on the outer peripheral surfaces 29 b and 30 b functioning as 12. Also, the upper end surface 29c of the first seal member 29 adjacent to the first seal space S1 and the upper end surface of the housing 7, and the lower end surface 30c of the second seal member 30 adjacent to the second seal space S2 and the lower side of the housing 7 are provided. An oil repellent film 14 is formed on the end face.

  In each of the embodiments described above, the plating film 13 is formed on the seal surface 12 of the seal member so that the filler exposed on the seal surface 12 is covered with the deburring process (skin layer removing process). However, the film to be provided on the seal surface 12 of the seal member may be an oil repellent film formed by solidifying the oil repellent. In this case, the oil repellent film to be provided on the seal member can be formed simultaneously on the seal surface 12 and the end surface exposed to the outside, but when the oil repellent film is formed on the seal surface 12 forming the seal space, On the contrary, there is a risk of promoting lubricating oil leakage. Such a situation can be prevented by performing UV treatment only on the oil-repellent film formed on the seal surface 12 among the oil-repellent films formed on each surface to lose the oil-repellent effect. Thereby, it is possible to reliably prevent the problem of lubricating oil leakage through the filler exposed on the sealing surface 12 and the lubricating oil leakage due to the oil repellent film being provided on the sealing surface 12.

  In the above, the coating (plating coating 13 or oil repellent film) is formed on the seal surface 12 to prevent leakage of the lubricating oil through the filler exposed on the seal surface 12 due to the deburring process. By removing the filler exposed on the seal surface 12 along with the deburring process, it is possible to prevent leakage of the lubricating oil through the exposed filler. Examples of the processing for removing the exposed filler include wrapping. Among the wrapping, a so-called aero wrap in which polishing is performed with a frictional force by which a medium having humidity and elasticity slides is particularly preferable.

  In the above description, the hydrodynamic bearing device has been described in which a seal member that is injection-molded using a resin material in which a thermoplastic resin is a base resin and various fillers are blended in an appropriate amount. It is also possible to perform injection molding using a so-called neat resin that does not contain any filler such as the base resin. With such a configuration, even if a deburring process is performed after molding, the filler is not exposed to the seal surface 12, and therefore no leakage of lubricating oil due to the exposure of the filler occurs. Therefore, there is no need to form a coating (plating coating 13 or oil repellent film) on the seal surface 12 or to remove the filler, and the hydrodynamic bearing device 1 that can reliably prevent leakage of the lubricating oil is further provided. Obtained at low cost.

  The seal member injection-molded with a neat resin may be inferior in mechanical properties such as strength compared to a seal member injection-molded with a resin material containing various fillers. In each of the embodiments shown in FIG. 4, the seal member is a member provided mainly for the purpose of forming a seal space with the counterpart member, and satisfies, for example, the strength required for the housing 7. Since there is no necessity, even if it is a case where it is such a structure, a special problem does not arise in actual use. However, when the seal member also functions as a retaining member for the shaft member 2 as in the embodiment shown in FIG. 5, attention is paid to the strength of the seal member as compared with the embodiment shown in FIGS. 2 and 4. There is a need.

  In the above description, the radial bearing portions R1 and R2 are exemplified by the configuration in which dynamic pressure is generated in the lubricating oil filling the radial bearing gap by the dynamic pressure grooves arranged in a herringbone shape or the like, but the radial bearing portion R1. , R2 may be a so-called step bearing, multi-arc bearing, or non-circular bearing. Further, the radial bearing portion can be formed at one place or three or more places in the axial direction in addition to being provided at two places separated in the axial direction as described above. Furthermore, a perfect circle bearing which does not have a dynamic pressure generating part can also be adopted as the radial bearing part.

  Further, as the thrust bearing portions T1, T2, a configuration in which dynamic pressure is generated in the lubricating oil filling the thrust bearing gap by the dynamic pressure grooves arranged in a spiral shape or the like is illustrated, but the thrust bearing portions T1, T2 are illustrated. Either one or both of them can be constituted by a so-called step bearing or wave bearing. Further, the thrust bearing portion can be constituted by a so-called pivot bearing that contacts and supports one end of the shaft member 2 instead of the dynamic pressure bearing as described above.

  Further, in the hydrodynamic bearing device 1 described above, the bearing member 10 is constituted by the housing 7 and the bearing sleeve 8 fixed to the inner periphery thereof. The bearing member 10 includes a portion corresponding to the housing 7 and a bearing. A portion corresponding to the sleeve 8 may be integrally provided.

It is sectional drawing which shows notionally the spindle motor for disk apparatuses. It is sectional drawing which shows 1st Embodiment of the hydrodynamic bearing apparatus which concerns on this invention. (A) is a sectional view of the bearing sleeve, and (b) is a diagram showing a lower end surface of the bearing sleeve. It is sectional drawing which shows 2nd Embodiment of the hydrodynamic bearing apparatus which concerns on this invention. It is sectional drawing which shows 3rd Embodiment of the hydrodynamic bearing apparatus which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fluid dynamic bearing apparatus 2 Shaft member 2a Shaft part 3 Disc hub 7 Housing 8 Bearing sleeve 9 Seal member 10 Bearing member 12 Seal surface 13 Plating film 14 Oil-repellent film S, S1, S2 Seal space R1, R2 Radial bearing part T1, T2 Thrust Bearing part

Claims (9)

A radial member in which at least one end is opened, a shaft member inserted into the inner periphery of the bearing member, and an oil film formed to face the outer peripheral surface of the shaft member to support the shaft member in the radial direction In a hydrodynamic bearing device comprising: a bearing gap; and a seal member disposed in an opening of the bearing member and forming a seal space communicating with the radial bearing gap.
A hydrodynamic bearing device, wherein the seal member is an injection-molded resin product from which the skin layer is removed, and a coating is formed on at least a seal surface facing the seal space of the seal member.   The hydrodynamic bearing device according to claim 1, wherein the coating is a plating coating.   2. The hydrodynamic bearing device according to claim 1, wherein the coating is an oil repellent film in which an oil repellent is solidified.   The hydrodynamic bearing device according to claim 3, wherein the oil repellent film formed on the seal surface is subjected to UV treatment. A radial member in which at least one end is opened, a shaft member inserted into the inner periphery of the bearing member, and an oil film formed to face the outer peripheral surface of the shaft member to support the shaft member in the radial direction In a hydrodynamic bearing device comprising: a bearing gap; and a seal member disposed in an opening of the bearing member and forming a seal space communicating with the radial bearing gap.
A hydrodynamic bearing device, wherein the sealing member is an injection molded product of a resin from which a skin layer is removed, and at least a sealing material facing the sealing space of the sealing member is subjected to a filler removing process. A radial member in which at least one end is opened, a shaft member inserted into the inner periphery of the bearing member, and an oil film formed to face the outer peripheral surface of the shaft member to support the shaft member in the radial direction In a hydrodynamic bearing device comprising: a bearing gap; and a seal member disposed in an opening of the bearing member and forming a seal space communicating with the radial bearing gap.
A hydrodynamic bearing device, wherein the seal member is an injection molded product of neat resin. A radial member in which at least one end is opened, a shaft member inserted into the inner periphery of the bearing member, and an oil film formed to face the outer peripheral surface of the shaft member to support the shaft member in the radial direction In a method for manufacturing a hydrodynamic bearing device comprising: a bearing gap; and a seal member that is disposed in an opening of the bearing member and that forms a seal space communicating with the radial bearing gap.
A method of manufacturing a hydrodynamic bearing device, comprising: removing a skin layer of a seal member injection-molded with a resin, and then forming a coating on at least a seal surface facing the seal space of the seal member.   8. The method of manufacturing a hydrodynamic bearing device according to claim 7, further comprising a step of applying an UV treatment to the oil repellent film formed on the seal surface, wherein the film is an oil repellent film formed by solidifying the oil repellent. A radial member in which at least one end is opened, a shaft member inserted into the inner periphery of the bearing member, and an oil film formed to face the outer peripheral surface of the shaft member to support the shaft member in the radial direction In a method for manufacturing a hydrodynamic bearing device comprising: a bearing gap; and a seal member that is disposed in an opening of the bearing member and that forms a seal space communicating with the radial bearing gap.
A method of manufacturing a hydrodynamic bearing device, comprising: removing a skin layer of a sealing member injection-molded with a resin, and then removing a filler on at least a sealing surface facing a sealing space of the sealing member.

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