JP2006105332A - Dynamic pressure bearing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve cost reduction of a dynamic pressure bearing device and to keep stable rotating performance. <P>SOLUTION: This dynamic pressure bearing device 1 is composed of a rotating member M composed of a shaft portion 2a, a flange portion 2b and a disc hub 3, and a bearing member 7 mounted on an outer periphery of the shaft portion 2a. The rotating member M is rotatably supported in a non-contact state by dynamic pressure effect generated in radial bearing clearance and thrust bearing clearance formed between these members. Here, a radial bearing surface A having a dynamic pressure generating portion formed by supplying a resin composition, is formed on a material surface of the shaft portion 2a, one end-side end face of the bearing member 7 is faced to the first thrust bearing clearance, and has a thrust bearing surface B formed by die forming and having a dynamic pressure generating portion. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a hydrodynamic bearing device. This hydrodynamic bearing device is a spindle of information equipment, for example, a magnetic disk device such as an HDD, an optical disk device such as a CD-ROM, CD-R / RW, DVD-ROM / RAM, or a magneto-optical disk device such as an MD or MO. It is suitable as a bearing device for a small motor such as a motor, a polygon scanner motor of a laser beam printer (LBP), a color wheel of a projector, or an electric device such as an axial fan.

As an example of the above-mentioned dynamic pressure bearing device, there can be mentioned a dynamic pressure bearing device that supports the shaft member in the radial direction and the thrust direction in a non-contact manner by the dynamic pressure action of the lubricating fluid generated in the radial bearing gap and the thrust bearing gap. As this type of hydrodynamic bearing device, dynamic pressure generating means is provided on the inner peripheral surface of a sleeve-like member (bearing sleeve) and on the end surface of the bearing sleeve facing the both end surfaces of the flange portion of the shaft member and the bottom surface of the housing. Are known (see, for example, Patent Document 1).
JP 2000-291648 A

  In addition to the shaft member, the above-described dynamic pressure bearing device includes a number of components such as a bearing sleeve and a housing that houses the bearing sleeve. In recent years, with the price reduction of information equipment, the demand for cost reduction for this type of hydrodynamic bearing device has become increasingly severe. To meet this demand, the number of parts has been reduced and the manufacturing process has been reviewed. There is an urgent need to further reduce costs.

  Therefore, an object of the present invention is to achieve further cost reduction of the hydrodynamic bearing device.

  In order to achieve the above object, in the present invention, a rotation member having a shaft portion, a bearing member having an inner peripheral surface opposed to an outer peripheral surface of the shaft portion, and a radial bearing gap between the shaft portion and the bearing member are generated. A radial bearing that supports the rotating member in a non-contact manner in the radial direction by the dynamic pressure of the fluid, and a thrust bearing that supports the rotating member in a non-contact manner in the thrust direction by the dynamic pressure of the fluid generated in the thrust bearing gap. In this structure, a resin composition is supplied to the material surface of the shaft part to form a dynamic pressure generating part for generating fluid dynamic pressure in the radial bearing gap, and one end opening of the bearing member is integrated with the bearing member. Alternatively, the first thrust bearing surface having a dynamic pressure generating portion is molded on the one end face of the bearing member which is closed by a separate lid member and faces the thrust bearing gap. Provide bearing device

  Unlike the above-described solving means for forming the dynamic pressure generating portion on the outer peripheral surface of the shaft portion, for example, when forming a dynamic pressure groove as the dynamic pressure generating portion on the inner peripheral surface of the sleeve-like member, The member is made of sintered metal, and a core rod having a groove mold is inserted into the inner periphery of the member and then pressed in the mold to transfer the groove mold to the inner peripheral surface of the sleeve-shaped member. A technique for forming a pressure groove is known (for example, Japanese Patent Application Laid-Open No. 11-182550). However, in this method, a sleeve-shaped member is accommodated and a bottomed cylindrical member (housing) that closes one end opening portion is separately prepared, and both are fixed accurately and securely by means such as adhesion or press-fitting. There is a need to. Therefore, the number of parts increases and the assembly process becomes complicated, which is one of the factors that hinder the cost reduction of the hydrodynamic bearing device.

  On the other hand, in the present invention, since the dynamic pressure generating portion is formed on the outer peripheral surface of the shaft portion of the shaft member, the dynamic pressure groove is formed on the inner peripheral surface of the sleeve-shaped member, for example. From the workability of the pressure groove, the sleeve-shaped member and the housing do not have to be separate members, and can be configured as a single member (bearing member) in which both are integrated. This difference is that, in terms of the outer shape, in the conventional product, a lid member that closes one end opening of the sleeve-like member is provided integrally or separately in a housing separated and independent from the sleeve-like member, In the product of the present invention, the lid member is provided integrally or separately with the bearing member. Thus, by integrating the conventional two members (sleeve-shaped member and housing) into one member (bearing member), the number of parts can be reduced and the assembly process between the two members can be omitted. Further cost reduction can be achieved.

  As a method of forming the dynamic pressure generating portion on the material surface forming the shaft portion, a resin composition is landed or dripped from the pore nozzle on the material surface and cured, for example, an inkjet method (hereinafter referred to as “inkjet method”). Etc.)).

  Conventionally, as a method of forming a dynamic pressure generating portion on the surface of a material, for example, a printing die is moved according to the rotation of the shaft member while being in contact with the outer peripheral surface of the shaft member, so that the dynamic pressure groove is formed on the outer periphery of the shaft member. There is known a method of printing other portions with a corrosion-resistant ink made of a resin composition (for example, Japanese Patent Publication No. 62-49351). However, in this method, due to the characteristics of the manufacturing method, a printing mold or a printing screen for holding the printing mold is necessary, and a large amount of ink is necessary for printing. Since corrosion of non-printed parts and ink removal are indispensable, it has been difficult to reduce costs.

  On the other hand, in the formation method of the dynamic pressure generating part by the ink jet method or the like, by programming in advance, an arbitrary shape pattern can be printed, and the discharge amount of the ink (resin composition) is precisely controlled. Each part of the shape pattern can be formed to an arbitrary thickness. Therefore, since the hardened ink itself can form a dynamic pressure generating portion with high accuracy, the shaft member in which the dynamic pressure generating portion is formed on the outer peripheral surface of the shaft portion is moved as it is without undergoing an ink removing process such as etching. It can be incorporated into a pressure bearing device and used as a bearing surface, and the manufacturing cost can be reduced by reducing the number of steps. In addition, since a printing mold corresponding to the shape of the dynamic pressure generating portion is not required, and the ink needs only a minimum amount for forming the dynamic pressure generating portion, the cost can be reduced. Further, in this case, theoretically, the ink on the bearing surface is in sliding contact with the bearing member, and the material of the shaft portion is not in contact with the bearing member. Therefore, the importance of wear resistance is a characteristic required for the material. Lower. Accordingly, the degree of freedom in selecting the material for the shaft portion can be increased, and the shaft member can be formed using an inexpensive material. From the same point of view, it is sufficient to select the material of the bearing member in consideration of the wear resistance against the resin, not the metal, and the degree of freedom of selection increases.

  Furthermore, in the present invention, since the first thrust bearing surface having the dynamic pressure generating portion is molded on the end surface on the one end side of the bearing member, the dynamic pressure generating portion can be efficiently formed on the bearing member. In view of this, further cost reduction can be achieved. In this case, if the bearing member is any one of a resin injection molded product, an MIM molded product, or a metal press molded product, the bearing member is molded, and at the same time as the molding, a first dynamic pressure generating portion is provided. Since the thrust bearing surface can be formed, a more efficient dynamic pressure generating portion can be formed.

  In addition to the above-described configuration, a second thrust bearing surface having a dynamic pressure generating portion may be molded on the end surface on the other end side of the lid member or the bearing member. In this way, by forming the second thrust bearing surface in addition to the first thrust bearing surface, the shaft member is moved in both thrust directions by the dynamic pressure action of the fluid generated in the two thrust bearing gaps respectively facing the both bearing surfaces. Can be supported in a non-contact manner. Since the second thrust bearing surface is molded, it can be molded efficiently and with high accuracy, thereby further reducing the cost. In this case, if the lid member is one of a resin injection molded product, an MIM molded product, or a metal press molded product, the second thrust bearing surface having a dynamic pressure generating portion is molded simultaneously with the molding of the lid member. Thus, the processing efficiency can be further improved.

  The lid member can be integrated with the bearing member in addition to being fixed to the bearing member as a separate member by means such as press fitting or adhesion.

  In the above-described configuration, the rotating member can be composed of, for example, a shaft member and a rotor portion that projects to the outer diameter side of the shaft member and has a rotor magnet mounting portion. In this case, it is desirable to arrange a magnetic material in at least a portion facing the rotor magnet in the rotor portion. According to this configuration, when the motor is driven, magnetic flux generated between the stator coil and the rotor magnet can be prevented from leaking through the rotor portion and the magnetic force can be prevented from being lost, and the rotational performance of the motor can be improved. .

  Examples of the method for fixing the shaft member to the rotor portion include caulking, spot welding, adhesion, electrodeposition, brazing, C clip fastening, screw fastening, and the like.

  A motor having the above-described configuration, a dynamic pressure bearing device, a rotor magnet, and a stator coil can be preferably used for the information equipment, particularly for a magnetic disk drive such as a hard disk (HDD).

  As described above, according to the present invention, it is possible to further reduce the cost of the hydrodynamic bearing device.

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

  FIG. 1 conceptually shows a configuration example of a spindle motor for information equipment incorporating a fluid dynamic bearing device 1 according to an embodiment of the present invention. This spindle motor for information equipment is used for a disk drive device such as an HDD, and includes a dynamic pressure bearing device 1, a disk hub 3 as a rotor portion attached to a shaft member 2 of the dynamic pressure bearing device 1, for example, A stator coil 4 and a rotor magnet 5 which are opposed to each other through a radial gap, and a bracket 6 are provided. 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 disk hub 3 holds one or more disks D such as magnetic disks on the outer periphery thereof. A bearing member 7 of the hydrodynamic bearing device 1 is mounted on the inner periphery of the bracket 6. When the stator coil 4 is energized, the rotor magnet 5 is rotated by an exciting force generated between the stator coil 4 and the rotor magnet 5, and the disk hub 3 and the shaft member 2 are rotated accordingly.

  FIG. 2 shows an example of the hydrodynamic bearing device 1. The hydrodynamic bearing device 1 includes a shaft member 2 having a shaft portion 2a at the center of rotation, a bearing member 7 having a sleeve-like portion and capable of inserting the shaft portion 2a into the inner periphery thereof, and one end of the bearing member 7 A lid member 8 that closes the side opening and a seal member 9 located on the other end side of the bearing member 7 are provided. For convenience of explanation, the lid member 8 side will be described below, and the seal member 9 side will be described upward.

  The shaft member 2 constitutes a rotating member M with a disk hub 3 attached to the upper end thereof. The shaft member 2 includes a shaft portion 2a and a flange portion 2b fixed to one end thereof. In the present embodiment, the shaft portion 2a and the flange portion 2b are formed as separate members, but may be integrally formed. On the outer peripheral surface 2a1 of the shaft portion 2a, a radial bearing surface A including a plurality of dynamic pressure grooves Ab arranged in a herringbone shape and a portion Aa that defines each dynamic pressure groove Ab is separated in the axial direction. Formed. On the upper radial bearing surface A, the dynamic pressure groove Ab is formed axially asymmetric with respect to the axial center m, and the axial dimension X1 of the upper region from the axial center m is the axial dimension X2 of the lower region. Is bigger than. For this reason, when the shaft member 2 rotates, the pulling force (pumping force) of the lubricating oil by the dynamic pressure groove Ab is relatively larger on the upper radial bearing surface than on the lower symmetrical radial bearing surface A. In the illustrated example, the radial bearing surface A is illustrated as being formed at two locations separated in the axial direction, but any number of radial bearing surfaces can be formed in the axial direction. Three or more places may be formed. In the present embodiment, both end surfaces 2b1 and 2b2 of the flange portion 2b are formed as flat surfaces having no dynamic pressure grooves.

  The partition portion Aa that partitions and forms the dynamic pressure groove Ab of the radial bearing surface A is formed by supplying a resin composition to the material surface of the shaft portion 2a. As the material, for example, a metal material such as stainless steel can be used. As an example of a resin composition supply method, in this embodiment, fluid ink (resin composition) is ejected from a nozzle in the form of fine droplets and landed on the outer peripheral surface 2a1 of the shaft portion 2a to be fixed. An ink jet method is employed in which the partition portion Aa that partitions the dynamic pressure groove Ab is printed.

  FIG. 3 shows an outline of an ink jet printing apparatus. As shown in the figure, this printing apparatus includes one or a plurality of nozzle heads opposed to the outer peripheral surface 2a1 of the material 2a 'of the shaft member 2 to be rotationally driven (the portion corresponding to the flange portion is not shown). 10 and a hardened portion 11 that is arranged with a circumferential position different from that of the nozzle head 10, and preferably arranged to face the nozzle head 10 with the material 2 a ′ interposed therebetween as shown in the figure. Element. The nozzle head 10 is provided with a plurality of nozzles 14 for discharging ink 12 in a microdroplet state in the axial direction. The ink 12 is a resin composition containing, for example, a photo-curable resin, preferably an ultraviolet curable resin as a base resin, and an ink mixed with an organic solvent in an appropriate ratio as needed. The curing unit 11 is a light source that emits light for curing the resin composition, and for example, an ultraviolet lamp is used.

  The nozzle head 10 is slid back and forth in the axial direction while rotating the material 2 a ′, and the ink 12 is ejected from the nozzles 14, whereby the fine droplets of the ink 12 land on a predetermined position on the outer peripheral surface 2 a 1 of the material 2 a ′. As a result of the collection of a large number of microdroplets, the outer peripheral surface 2a1 of the material 2a ′ has, as a dynamic pressure generating portion, for example, a dynamic pressure groove Ab arranged in a herringbone shape and a partition portion Aa that partitions the dynamic pressure groove Ab. A dynamic pressure groove pattern is formed. The printing of the dynamic pressure groove pattern is performed so as to gradually progress in the circumferential direction as the shaft member 2 rotates, and when the printed portion reaches the opposite area of the curing portion 11, the ink 12 that has been irradiated with ultraviolet rays is A polymerization reaction is caused to cure sequentially. The shaft member is rotated one to several tens of times while appropriately switching the supply / stop of the ink from each nozzle to form a dynamic pressure groove pattern on the entire circumference of the shaft portion 2a. At this time, since the nozzle head 10 and the curing unit 11 are disposed at opposing positions sandwiching the material 2a ′, the ultraviolet rays irradiated from the curing unit 11 are shielded by the material 2a ′ and the ink 12 ejected from the nozzle 14 is used. Does not have a curing effect due to the polymerization reaction. Therefore, the clogging of the nozzle 14 due to the cured ink 12 can be prevented, and the dynamic pressure groove pattern can be efficiently formed.

  The ink fixing method is not limited to the above-described ink jet method, for example, a method of discharging droplets using electrophoresis, a so-called nozzleless type droplet discharging method, or a method of discharging ink via a micropipette. It is also possible to use a method in which the ink is continuously ejected on the surface of the material instead of in a droplet state, or a method in which the distance to the material surface is shortened and ink is brought into contact with the fixing surface simultaneously with ejection.

  As described above, the dynamic pressure generating portion is formed on the shaft portion 2a by landing or dripping the resin composition and then curing and forming a partition, for example, an inkjet method, thereby performing a conventional process such as etching. It can be omitted and used as the radial bearing surface A by being incorporated in the hydrodynamic bearing device 1 as it is. Furthermore, since supply of surplus ink and consumables such as a printing die are not required, the process can be omitted and the consumables can be reduced. Moreover, since the dynamic pressure generating portion made of the resin composition formed on the shaft portion 2a is formed in a convex shape from the surface of the material, the material of the shaft portion 2a does not make sliding contact with the bearing member 7. Therefore, the metal material forming the shaft portion 2a does not need to consider wear resistance and the like, and a cheaper metal material can be selected, so that the cost of the hydrodynamic bearing device 1 can be further reduced. Become.

  The bearing member 7 is formed in a substantially cylindrical shape. The illustrated bearing member 7 includes a sleeve portion 7a and a seal mounting portion 7b above the sleeve portion 7a. The inner peripheral surface 7a1 of the sleeve portion 7a has a smaller diameter than the inner peripheral surface 7b1 of the seal mounting portion 7b, and faces the two radial bearing surfaces A of the shaft member 2. The outer periphery of the lower end of the seal mounting portion 7b is partially reduced in diameter, and a lid member 8 described later is fitted and fixed to the outer peripheral surface 7a3 of the reduced diameter portion. On the lower end surface 7a2 of the sleeve portion 7a, as shown in FIG. 4, a plurality of dynamic pressure grooves 7a5 arranged in a spiral shape, for example, as dynamic pressure generating portions, and a partition portion 7a6 that partitions each dynamic pressure groove 7a5. A first thrust bearing surface B including is formed.

  The bearing member 7 is integrally formed by any one of press molding of a metal material such as soft metal, injection molding of a resin material, or MIM molding. In any molding method, a bearing corresponding to the shape of the dynamic pressure generating portion of the first thrust bearing surface B is formed on the portion of the molding die that forms the lower end surface 7a2 of the sleeve portion 7a. Simultaneously with the molding of the member 7, the first thrust bearing surface B can be molded. As a result, stable machining accuracy of the dynamic pressure generating portion can be maintained, the number of machining steps can be reduced, cycle time can be shortened, and cost can be reduced.

  The lid member 8 is formed in a substantially bottomed cylindrical shape that is separate from the bearing member 7. The lid member 8 includes a cylindrical side portion 8a and a bottom portion 8b that seals the lower end opening of the side portion 8a. In the illustrated example, the side portion 8a and the bottom portion 8b are integrally formed. As shown in FIG. 5, the upper end surface 8b1 of the bottom 8b includes a plurality of dynamic pressure grooves 8b2 arranged in a spiral shape, for example, as a dynamic pressure generating portion, and a partition portion 8b3 that partitions each dynamic pressure groove 8b2. A second thrust bearing surface C is formed. In addition, the side part 8a and the bottom part 8b can also be made into a different body.

  Similar to the bearing member 7, the lid member 8 is integrally formed by any one of press molding of a metal material such as soft metal, injection molding of a resin material, or MIM molding. In any of the molding methods, a lid member 8 is formed by forming a mold corresponding to the shape of the dynamic pressure generating portion of the second thrust bearing surface C at a portion where the upper end surface 8b1 of the bottom 8b of the mold is to be molded. The second thrust bearing surface C can be formed at the same time as the mold is formed, and further cost reduction is achieved.

  The lid member 8 is fixed to the bearing member 7 by fitting the inner peripheral surface 8a1 of the side portion 8a to the outer peripheral surface 7a3 of the reduced diameter portion of the bearing member 7 and applying appropriate means such as press-fitting, adhesion, and welding. . At this time, the flange portion 2 b of the shaft member 2 is accommodated in a space between the lower end surface 7 a 2 of the sleeve portion 7 a of the bearing member 7 and the upper end surface 8 b 1 of the bottom portion 8 b of the lid member 8. The upper end surface 8a2 of the side portion 8a of the lid member 8 is in contact with a shoulder surface 7a4 formed on the outer periphery of the sleeve portion 7a of the bearing member 7, whereby a later-described thrust bearing gap is managed to a specified width.

  In addition, the material selection of the bearing member 7 and the cover member 8 can be suitably selected corresponding to the required bearing characteristics. At this time, the lid member 8 and the bearing member 7 may be formed of either different materials or the same materials.

  The seal member 9 is formed in a ring shape with a metal material or a resin material. In this embodiment, the seal member 9 is formed separately from the bearing member 7, and is fixed to the inner peripheral surface 7b1 of the seal mounting portion 7b of the bearing member 7 by means such as press-fitting, adhesion, and welding. The inner peripheral surface 9a of the seal member 9 is increased in diameter in a tapered manner toward the upper side. Between the inner peripheral surface 9a and the outer peripheral surface 2a1 of the shaft portion 2a facing the inner peripheral surface 9a, An annular seal space S in which the radial dimension gradually increases as it goes to is formed. Lubricating oil is injected into the internal space of the hydrodynamic bearing device 1 sealed with the seal member 9, and the hydrodynamic bearing device 1 is filled with the lubricating oil. In this state, the oil level of the lubricating oil is maintained within the range of the seal space S. In order to reduce the number of parts and the number of assembly steps, the seal member 9 can be integrally formed with the bearing member 7.

  In the hydrodynamic bearing device 1 having the above-described configuration, when the shaft member 2 rotates, the radial bearing surfaces A formed on the outer peripheral surface 2a1 of the shaft portion 2a are separated from the inner peripheral surface 7a1 of the sleeve portion 7a of the bearing member 7, respectively. Opposing through the bearing gap. As the shaft member 2 rotates, the lubricating oil filled in the radial bearing gaps generates a dynamic pressure action, and the shaft member 2 is rotatably supported in the radial direction by the pressure. As a result, the first radial bearing portion R1 and the second radial bearing portion R2 that support the shaft member 2 in a non-contact manner so as to be rotatable in the radial direction are formed.

  Similarly, a second thrust bearing formed between the first thrust bearing surface B formed on the lower end surface 7a2 of the bearing member 7 and the upper end surface 2b1 of the flange portion 2b and on the upper end surface 8b1 of the lid member 8. Thrust bearing gaps are respectively formed between the surface C and the lower end face 2b2 of the flange portion 2b. As the shaft member 2 rotates, the lubricating oil filled in both thrust bearing gaps generates a dynamic pressure action, The shaft member 2 is supported by the pressure in a non-contact manner so as to be rotatable in the thrust direction. Thereby, the first thrust bearing portion T1 and the second thrust bearing portion T2 that support the shaft member 2 in a non-contact manner so as to be rotatable in both directions of the thrust are formed.

  Although illustration is omitted, in order to balance the pressure generated in the bearing clearances of the radial bearing portions R1, R2 and the thrust bearing portions T1, T2, one end of the bearing member 7 is the first thrust bearing portion T1. It is desirable to form a flow path for oil circulation that opens near the outer periphery and opens at the other end above the first radial bearing portion R1.

  As described above, the hydrodynamic bearing device 1 of the present invention has a structure in which the conventional sleeve-shaped member and the housing are integrated as the bearing member 7, so that the number of parts is reduced and the assembly process between the two members is omitted. Thus, the cost of the hydrodynamic bearing device can be reduced. In the present invention, the bearing member 7 and the lid member 8 are any one of a resin injection molded product, an MIM molded product, and a metal press molded product, and the bearing member 7 has a dynamic pressure generating portion. Since the second thrust bearing surface C having the dynamic pressure generating portion is formed on the surface B and the lid member 8, the thrust bearing surfaces B and C can be formed simultaneously with the molding of these members 7 and 8. it can. Therefore, compared with the case where the thrust bearing surfaces B and C are formed on the flange end faces 2b1 and 2b2 by forging after the shaft member 2 is formed, the processing steps are omitted and the cost is further reduced. Can do.

  As shown in FIG. 1, in the hydrodynamic bearing device 1 of the present invention, the outer peripheral surface of the bearing member 7 (and the outer peripheral surface of the lid member 8 as necessary) is fixed to the inner periphery of the bracket 6, and the shaft member 2. A disk hub 3 as a rotor portion is mounted on the upper end of the spindle motor and incorporated in the spindle motor. The disc hub 3 includes a plate portion 3a having a substantially disk shape and a cylindrical portion 3b integrally formed on the outer periphery of the plate portion 3a. For example, caulking, welding (spot welding, etc.), adhesion, electrodeposition, brazing The shaft member 2 is fixed to the upper end of the shaft member 2 by means such as a C clip or a screw.

  The disk hub 3 can be formed by, for example, injection molding of a resin material. When the disk hub 3 is made of a resin material in this manner, the magnetic flux generated between the stator coil 4 and the rotor magnet 5 may leak through the disk hub 3 and cause magnetic loss, but as shown in FIG. If the magnetic shield member 20 made of a ferromagnetic metal material is interposed between the inner peripheral surface 3b1 of the cylindrical portion 3b and the magnet 5, such a problem can be solved. The magnetic shield member 20 can be integrally formed with the disk hub 3 by insert molding, for example. When the disk hub 3 itself is made of a ferromagnetic material, the magnetic shield member 20 is not necessary.

  Although one embodiment of the present invention has been described above, the present invention is not limited to this embodiment, and can be preferably used in a hydrodynamic bearing device described below. In the embodiments described below, members and elements having the same functions as those in the embodiment shown in FIG.

  FIG. 6 shows another embodiment of the hydrodynamic bearing device. The hydrodynamic bearing device 30 of this embodiment is greatly different from the embodiment shown in FIG. 2 in that the second thrust bearing portion T2 shown in FIG. 2 has an upper end surface 7e2 of the bearing member 7 and a disk hub 3 facing this. The seal space S is formed between the upper end outer peripheral surface 7e1 of the bearing member 7 and the inner peripheral surface 3b1 of the cylindrical portion 3b of the disk hub 3. It is in the point.

  Also in this embodiment, the bearing member 7 is a resin injection molded article having a form in which a conventional housing and a sleeve-like member are integrally formed, and the first thrust is formed on the lower end surface 7a2 of the bearing member 7. Since the second thrust bearing surface C is molded on the bearing surface B and further on the upper end surface 7e2 of the bearing member 7, the cost of the hydrodynamic bearing device can be reduced as in the embodiment shown in FIG. Can do.

  In each of the embodiments described above, the lid member 8 and the bearing member 7 are separate members. However, this is for assembly reasons, and for example, a bearing in which the flange portion 2b of the shaft member 2 is omitted. If there is no particular inconvenience in assembly, such as in an apparatus, the lid member 8 and the bearing member 7 can be integrally formed. The hydrodynamic bearing device 40 shown in FIG. 7 is an example thereof, and the flange portion 2b of the shaft member 2 is omitted. Also in this embodiment, a thrust bearing surface is molded on the upper end surface 7e2 of the bearing member 7. The thrust bearing portion T is only formed between the upper end surface 7e2 of the bearing member 7 and the lower end surface 3a1 of the plate portion 3a in the disk hub 3 opposed to the upper end surface 7e2.

  Furthermore, in the above embodiment, as the dynamic pressure bearings constituting the radial bearing portions R1, R2 and the thrust bearing portions T1, T2, T, for example, a dynamic pressure generating portion including a herringbone shape or a spiral shape dynamic pressure groove is provided. Although the used bearing is illustrated, the structure of the dynamic pressure generating portion is not limited to this. As the radial bearing portions R1 and R2, for example, a so-called multi-arc bearing in which a radial bearing gap is reduced in a wedge shape in one or both of the circumferential directions at a plurality of locations in the circumferential direction, axially extending motion It can also be comprised with what is called a step bearing which formed the pressure groove in the multiple places of the circumferential direction. Further, as the thrust bearing portions T1, T2, and T, it is possible to adopt a configuration in which the thrust bearing gap is reduced to a wedge shape in one or both of the circumferential directions at a plurality of locations in the circumferential direction.

1 is a cross-sectional view of a spindle motor for information equipment incorporating a fluid dynamic bearing device according to an embodiment of the present invention. It is sectional drawing of the dynamic pressure bearing apparatus which concerns on one Embodiment. 1 is a schematic diagram of an inkjet printing apparatus. It is the figure which looked at the lower end surface of the bearing member from the lower part. It is the figure which looked at the upper end face of the lid member from the upper part. It is sectional drawing of the hydrodynamic bearing apparatus which concerns on other embodiment. It is sectional drawing of the hydrodynamic bearing apparatus which concerns on other embodiment.

Explanation of symbols

1, 30, 40 Dynamic pressure bearing device 2 Shaft member 2a Shaft portion 2b Flange portion 3 Disc hub 4 Stator coil 5 Rotor magnet 7 Bearing member 7a5 Dynamic pressure groove 8 Lid member 8b2 Dynamic pressure groove 9 Seal member 20 Magnetic shield member A Radial Bearing surface Ab Dynamic pressure groove B, C Thrust bearing surface M Rotating member R1, R2 Radial bearing portion T1 First thrust bearing portion T2 Second thrust bearing portion T Thrust bearing portion S Seal space

Claims (8)

A rotary member having a shaft portion, a bearing member having an inner peripheral surface opposed to the outer peripheral surface of the shaft portion, and a dynamic pressure action of fluid generated in a radial bearing gap between the shaft portion and the bearing member causes the rotary member to be radial. A radial bearing portion that supports the contact member in the non-contact direction, and a thrust bearing portion that supports the rotating member in a non-contact manner in the thrust direction by the dynamic pressure action of the fluid generated in the thrust bearing gap.
A resin composition is supplied to the material surface of the shaft part, and a dynamic pressure generating part for generating fluid dynamic pressure in the radial bearing gap is formed.
One end opening of the bearing member is closed by a lid member that is integral with or separate from the bearing member, and a first thrust bearing surface having a dynamic pressure generating portion is molded on one end surface of the bearing member facing the thrust bearing gap. A hydrodynamic bearing device characterized by that.   2. The hydrodynamic bearing device according to claim 1, wherein the dynamic pressure generating portion is formed by landing or dripping the resin composition on the surface of the material from the nozzle and then curing the resin composition.   The hydrodynamic bearing device according to claim 1 or 2, wherein a second thrust bearing surface having a hydrodynamic pressure generating portion is molded on the lid member.   The hydrodynamic bearing device according to claim 1 or 2, wherein a second thrust bearing surface having a dynamic pressure generating portion is molded on an end surface on the other end side of the bearing member.   The hydrodynamic bearing device according to any one of claims 1 to 4, wherein the bearing member is any one of a resin injection molded product, an MIM molded product, and a metal press molded product.   The hydrodynamic bearing device according to any one of claims 1 to 5, wherein the lid member is one of a resin injection molded product, an MIM molded product, or a metal press molded product.   The rotating member includes a shaft portion and a rotor portion that projects to an outer diameter side of the shaft portion and has a rotor magnet mounting portion, and at least a portion of the rotor portion facing the rotor magnet is provided with a magnetic material. The hydrodynamic bearing device according to any one of 1 to 6.   A motor comprising the hydrodynamic bearing device according to claim 1, a rotor magnet, and a stator coil.

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