JP2007247807A - Fluid bearing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce a cost and a size of a fluid bearing device having a magnetic seal. <P>SOLUTION: The fluid bearing device 1 comprises a rotary member, a fixed member, magnetic fluid filling the bearing clearance formed between both members, and a magnetic seal for preventing the leakage of the magnetic fluid by means of a magnet 10 provided on at least any one of the rotary member and the fixed member, and rotatably supports the rotary member via the magnetic fluid film formed in the bearing clearance, wherein the magnetic seal magnet provided on the outer peripheral surface 2a1 of the shaft member 2 magnetizes the aggregate of a very small amount of ink including a magnetic material. A magnetic circuit is formed between the magnet portion 10 and the seal member 9 made of a magnetic material. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a hydrodynamic bearing device.

  The hydrodynamic bearing device rotatably supports a shaft to be supported by a fluid film formed in a bearing gap. This hydrodynamic bearing device has features such as high-speed rotation, high rotation accuracy, and low noise. In recent years, this feature has been utilized to make use of the features, such as magnetic disk devices such as HDD and FDD, CD-ROM, CD- For spindle motors such as optical disk devices such as R / RW and DVD-ROM / RAM, magneto-optical disk devices such as MD and MO, for polygon scanner motors of laser beam printers (LBP), and for fan motors of personal computers (PC) It is widely used as a color wheel for projectors, or as a bearing for electric devices such as small motors such as axial fans.

  In this type of hydrodynamic bearing device, a radial bearing portion that supports a shaft to be supported in the radial direction and a thrust bearing portion that supports in the thrust direction are provided. As the radial bearing portion, there are a case where a dynamic pressure bearing provided with a dynamic pressure generating portion for generating a dynamic pressure in a lubricating fluid that fills the bearing gap is used, and a case where a circular bearing without such a dynamic pressure generating portion is provided. It may be used. On the other hand, as the thrust bearing portion, there are a case where a dynamic pressure bearing is used, and a case where a bearing (so-called pivot bearing) having a structure supporting contact is used.

For example, disk devices are extremely reluctant to contaminate with a lubricating fluid due to the nature of the product. Therefore, a seal mechanism for preventing leakage of the lubricating fluid is usually provided at the opening of the hydrodynamic bearing device incorporated in the disk device. As a sealing mechanism, for example, a sealing magnet is provided in an opening of a bearing member, and a sealing space and a magnetic circuit are formed between the sealing magnet and a shaft member (so-called magnetic seal). is there. In this case, the lubricating fluid (magnetic fluid) filled in the seal space is subjected to the magnetic holding force by the magnetic circuit in addition to the pulling force to the bearing inside due to the capillary force, so external leakage of the lubricating fluid is effective (For example, refer to Patent Document 1).
Japanese Patent Laid-Open No. 10-30732

  In general, a magnet is obtained by molding a magnetic material powder, but the magnetic material itself is expensive and its manufacturing cost is high. Therefore, when this type of magnet is used in a seal mechanism (magnetic seal), the cost of the hydrodynamic bearing device is increased. In addition, since a large space is required for installing the magnet, this point may be an obstacle to downsizing the hydrodynamic bearing device.

  An object of the present invention is to reduce the cost and further reduce the size of a hydrodynamic bearing device having a magnetic seal.

  In order to achieve the above object, a hydrodynamic bearing device according to the present invention is provided in any one of a rotating member, a fixed member, a magnetic fluid satisfying a bearing gap formed between both members, and the rotating member and the fixed member. And a magnetic seal that prevents leakage of magnetic fluid with a magnet, and rotatably supports a rotating member via a magnetic fluid film formed in a bearing gap, and the magnet of the magnetic seal includes a magnetic body It is characterized by being formed by magnetizing an aggregate of a small amount of ink.

  In the configuration of the present invention, the magnet of the magnetic seal is formed by magnetizing an aggregate of a small amount of ink containing a magnetic material. In this case, since the base structure of the magnet is ink (resin), the cost of the hydrodynamic bearing device can be reduced compared to the conventional configuration in which one side constituting the magnetic seal is a sealing magnet.

  A collection of minute amounts of ink that forms a magnet is a method in which minute droplets of ink supplied from an ink supply unit such as a nozzle are landed or dropped in a non-contact manner on the surface of the member, and each droplet is collected, for example, printing by an ink jet method Can be formed. In this printing method, the ink supply amount and supply location can be precisely controlled by a program, so by programming in advance and controlling the position of the ink supply unit and ink supply / stop according to the program A magnet having an arbitrary shape can be easily formed on the surface of a member having various shapes. Therefore, it is possible to easily form the magnet in a minute shape such as a thin film, and it is not necessary to consider the installation space of the magnet, and the hydrodynamic bearing device can be downsized.

  As a method for supplying ink in a non-contact manner with the surface of the member when forming the above-mentioned magnet portion, in addition to printing by the above-described ink jet method, a method of ejecting ink droplets from the ink liquid surface instead of the nozzle (nozzle) Less inkjet method), a method of inducing ink using electrophoresis, a method of ejecting ink continuously through a micropipette instead of a droplet, or a distance to the fixing surface, A method of landing ink on the fixing surface at the same time as discharging can also be adopted.

  As the ink, in addition to the thermosetting type, for example, a type that can be cured by irradiation with an electron beam, light, or the like can be used. In particular, in consideration of cost and work environment, the ink is cured by irradiation with light. It is desirable to have photocurability. As the photocurable ink, a visible light curable ink can be used in addition to an ultraviolet curable type or an infrared curable type, but an ultraviolet curable type that can be cured at a low cost in a short time is particularly desirable. .

  The hydrodynamic bearing device having the above configuration can be preferably used for a motor having the hydrodynamic bearing device, a stator coil, and a rotor magnet, and in particular, a spindle motor for information equipment that dislikes contamination by a lubricating fluid.

  As described above, according to the present invention, it is possible to reduce the cost and further reduce the size of a hydrodynamic bearing device having a magnetic seal.

  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 hydrodynamic bearing device 1 according to an embodiment of the present invention. This spindle motor is used for 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 mounted on the shaft member 2, and a radial gap, for example. And a stator magnet 4 and a rotor magnet 5 which are opposed to each other. 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 a plurality (two in FIG. 1) of a disk-shaped information storage medium (hereinafter simply referred to as a disk) D such as a magnetic disk on its outer periphery. In the above configuration, when the stator coil 4 is energized, the rotor magnet 5 is rotated by the electromagnetic force generated between the stator coil 4 and the rotor magnet 5, and accordingly, the disk hub 3 and the disk hub 3 hold the rotor magnet 5. The disk D rotates together with the shaft member 2.

  FIG. 2 shows an example of a hydrodynamic bearing device 1 having the configuration of the present invention. The hydrodynamic bearing device 1 includes a rotating member and a fixed member. In this embodiment, the rotating member is a shaft member 2, and the fixed member is a housing 7, a bearing sleeve 8 fixed to the housing 7, and a seal. It is comprised with the member 9. FIG. For convenience of explanation, the bottom 7b side of the housing 7 will be described below, and the side opposite to the bottom 7b will be described as the upper side.

  The housing 7 is formed in a bottomed cylindrical shape with a resin composition using LCP, PPS, PEEK or the like as a base resin, and includes a cylindrical portion 7a and a bottom portion 7b integrally formed at the lower end of the cylindrical portion 7a. . One or more kinds of various fillers such as a reinforcing material, a lubricant, and a conductive material are blended in the resin composition constituting the housing 7 as necessary. The housing 7 can also be formed of a soft metal material such as brass or an aluminum alloy.

  The entire surface or a partial annular region of the upper end surface 7b1 of the bottom portion 7b serves as a thrust bearing surface of the second thrust bearing portion T2, and the thrust bearing surface has, for example, a plurality of dynamic arrays arranged in a spiral shape as dynamic pressure generating portions. A pressure groove is formed (not shown). This dynamic pressure groove is formed at the same time as the housing 7 by machining the groove mold for forming the dynamic pressure groove in a required part of the mold for molding the housing 7 (the part for molding the upper end surface 7b1). Can do. Further, a step portion 7d that engages with the lower end surface 8c of the bearing sleeve 8 and performs axial positioning is integrally formed at a position that is separated from the upper end surface 7b1 in the axial direction by a predetermined dimension.

  The bearing sleeve 8 is formed in a cylindrical shape, for example, a porous body made of sintered metal, particularly a sintered body of sintered metal mainly composed of copper, and the lower end face 8 c is brought into contact with the step portion 7 d of the housing 7. In this state, it is fixed to the inner peripheral surface 7a1 by appropriate means such as press-fitting, bonding, press-fitting or welding. Note that the bearing sleeve 8 can be formed of not only a sintered metal but also a metal material other than a porous body, for example, a soft metal such as brass.

  The inner peripheral surface 8a of the bearing sleeve 8 is provided with two upper and lower regions that are radial bearing surfaces of the first radial bearing portion R1 and the second radial bearing portion R2, and are separated from each other in the axial direction. For example, herringbone-shaped dynamic pressure grooves 8a1 and 8a2 as shown in FIG. 3A are formed. The upper dynamic pressure groove 8a1 is formed axially asymmetric with respect to the axial center m (the axial center of the upper and lower inclined groove regions), and the 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 grooves 8a2 are formed symmetrically in the axial direction, and the axial dimensions of the upper and lower regions thereof are respectively equal to the axial dimension X2. In this case, when the shaft member 2 rotates, the pulling force (pumping force) of the lubricating oil by the dynamic pressure groove is relatively larger in the upper dynamic pressure groove 8a1 than in the lower symmetrical dynamic pressure groove 8a2. The dynamic pressure grooves can be formed in other known shapes such as a spiral shape. One or a plurality of axial grooves 8b1 are formed on the outer peripheral surface 8b of the bearing sleeve 8 over the entire axial length.

  In addition, a thrust bearing surface of the first thrust bearing portion T1 is formed in a part or all of the annular region of the lower end surface 8c of the bearing sleeve 8, and the region serving as the thrust bearing surface includes, for example, FIG. A spiral-shaped dynamic pressure groove 8c1 as shown in FIG. The dynamic pressure groove can be formed in, for example, a herringbone shape in addition to the spiral shape. Further, the dynamic pressure groove may be formed on the upper end surface 2b1 of the flange portion 2b of the shaft member 2 facing each other through the thrust bearing gap.

  The shaft member 2 is formed of a non-magnetic and high-rigidity metal material such as austenitic stainless steel (for example, SUS304), and the shaft portion 2a and a flange provided integrally or separately at the lower end of the shaft portion 2a Part 2b. In addition, the shaft member 2 can also have a hybrid structure of a metal material and a resin material. In this case, the sheath portion including at least the outer peripheral surface 2a1 of the shaft portion 2a is formed of the metal, and the remaining portion (for example, the shaft portion) The core part of the part 2a and the flange part 2b) are formed of resin. Both the outer peripheral surface 2a1 of the shaft portion 2a and both end surfaces 2b1, 2b2 of the flange portion 2b are formed as smooth surfaces without a dynamic pressure groove or the like.

  A seal member 9 is disposed on the inner periphery of the upper end portion of the cylindrical portion 7 a of the housing 7. The seal member 9 is formed in an annular shape with a magnetic material, and is disposed on the inner periphery of the upper end portion of the cylindrical portion 7 a of the housing 7. As a magnetic material, in addition to a metal material having magnetism, a resin material in which a magnetic material is dispersed can be used. The inner peripheral surface 9a of the seal member 9 has a tapered shape that gradually increases in diameter upward, and between the inner peripheral surface 9a and the outer peripheral surface 2a1 of the shaft portion 2a facing the upper surface, the upward direction is provided. An annular seal space K having a gradually increasing radial dimension is formed. The interior space of the hydrodynamic bearing device 1 sealed by the seal member 9 is filled with a magnetic fluid as a lubricating fluid.

  In the present embodiment, a magnet (magnet portion) 10 is provided between the outer peripheral surface 2a1 of the shaft portion 2a and the inner peripheral surface 9a of the seal member 9 in a region facing the inner peripheral surface 9a. Is formed in a band shape over the entire circumference of the shaft portion 2a. Therefore, in a state where the fluid bearing device 1 is filled with the magnetic fluid, the magnetic fluid in the seal space K is attracted to the inside of the bearing by the capillary force and magnetized by the magnetic circuit passing through the magnet portion 10 and the seal member 9. With the target holding force, the structure is always maintained below the magnet portion 10 within the range of the seal space K.

  Hereinafter, a method for forming the magnet portion 10 on the outer peripheral surface 2a1 of the shaft portion 2a will be described with reference to the drawings.

  FIGS. 4A and 4B show a manufacturing apparatus used for forming the magnet portion 10. In this manufacturing apparatus, the shaft member 2 is rotatably supported by the holding portions 14 on both sides in the axial direction, and is rotationally driven at a constant speed by the driving force of the driving source 17 such as a motor.

  On the outer periphery of the shaft portion 2a of the shaft member 2, the nozzle head 11, the curing device 13, and the magnetizing device 16 are arranged at different circumferential positions.

  The nozzle head 11 ejects micro droplets 15 of ink on the outer peripheral surface 2a1 of the opposed shaft portion 2a by an ink jet method, and is externally fitted to a guide so that it can slide in the axial direction as necessary. In the nozzle head 11, a plurality of nozzles 12 that eject ink in the form of minute droplets are arranged in a plurality of rows and columns. The discharge form of the ink from the nozzle 12 is not particularly limited, and various discharge forms such as a piezo form, a thermal ink jet method, and an air jet method are selected. Further, the ink jet printing method may be either a continuous (continuous) method or an on-demand method.

  As the ink, magnetic ink in which a magnetic material is blended with ultraviolet curable ink is used. As the magnetic material, a rare earth magnetic powder, for example, a powder of strontium ferrite BH-4310 manufactured by Nippon Valve Industrial Co., Ltd. can be used. In addition, a known magnetic material such as barium ferrite can be used. The blending ratio of the magnetic material to the ultraviolet curable ink is 3 to 60 wt%, desirably 5 to 50 wt%. If the blending ratio is less than 3 wt%, a sufficient magnetic force that can hold the magnetic fluid cannot be obtained. On the other hand, if it exceeds 60 wt%, the viscosity of the ink becomes too high to be ejected from the nozzle 12. It is.

  The ultraviolet curable ink is fixed by causing a polymerization reaction by irradiation with ultraviolet rays, and any liquid polymer material including a liquid polymer material and a solvent can be used as long as the ink can be discharged from the nozzle 12. . Any organic solvent may be used as long as it has a property of dissolving ultraviolet curable ink.

  Examples of the ultraviolet curable resin constituting the base resin of the ultraviolet curable ink include radical polymerization monomers, radical polymerization oligomers, cationic polymerization monomers, imide acrylates, and ene thiols represented by cyclic polyene compounds and polythiol compounds. Among them, radical polymerization monomers, radical polymerization oligomers, and cationic polymerization monomers can be preferably used. As the radical polymerization monomer, for example, a monofunctional, bifunctional or polyfunctional acrylate monomer or methacrylate monomer can be used. As the radical polymerization monomer, for example, urethane acrylate, epoxy acrylate, polyester acrylate, or unsaturated. Polyester can be used. Examples of the cationic polymerization monomer include bisphenol A epoxy resin, phenol novolac epoxy resin, alicyclic epoxy resin, 3-ethyl-3-hydroxymethyloxetane, 1,4-bis {[(3- Ethyl-3-oxetanyl) methoxy] methyl} benzene, 3-ethyl-3- (phenoxymethyl) oxetane, di [1-ethyl (3-oxetanyl)] methyl ether, 3-ethyl-3- (2-ethylhexyl) Oxetane resins such as siloxymethyl) oxetane and 3-ethyl-3-{[3- (triethoxysilyl) propoxy] methyl} oxetane can be used. These ultraviolet curable resins can be used alone, or a mixture of two or more types can be used as the base resin.

  These base resins can be blended with a photopolymerization initiator such as a radical photopolymerization initiator for causing a polymerization reaction by ultraviolet irradiation or a cationic photopolymerization initiator. Examples of radical photopolymerization initiators include hydrogen represented by benzophenone, methyl orthobenzoin benzoate, 4-benzoyl-4′-methyldiphenyl sulfide, ammonium salt of benzophenone, isopropylthioxanthone, diethylthioxanthone, and ammonium salt of thioxanthone. Pull-out photopolymerization initiators can be used, or benzoin derivatives, benzyldimethyl ketal, α-hydroxyalkylphenone, α-aminoalkylphenone, acylphosphine oxide, monoacylphosphine oxide, bisacylphosphine oxide, acrylphenylglycol Intramolecular cleavage type photopolymerization initiators typified by oxylate, diethoxyacetophenone and titanocene compounds can be used. Examples of the cationic photopolymerization initiator include triphenylsulfonium hexafluoroantimonate, triphenylsulfonium hexafluorophosphate, SP-170 and SP-150 (both manufactured by Asahi Denka Co., Ltd.), FC-508, Polyarylsulfonium salts exemplified by FC-512 (both manufactured by 3M Company), UVE-1014 (manufactured by General Electric Company), triallyl sulfone exemplified by Uvacure 1590 and Uvacure 1591 (both manufactured by Daicel UCB) Mixtures of muhexafluorophosphade salts, metallocene compounds exemplified by Irg-261 (Ciba Geigy), diphenyliodonium hexafluoroantimonate and P-nonylphenylphenyliodonium Kisa hexafluoroantimonate, poly aryl iodonium salts such as 4,4'-diethoxy-phenyl iodonium hexafluoroantimonate can be used. These photopolymerization initiators can be used alone or in combination of two or more.

  In addition, although the ultraviolet curing type was illustrated as a magnetic ink, a thermosetting magnetic ink can also be used.

  When the ultraviolet curable ink is used as described above, an ultraviolet irradiation lamp is used as the curing device 13. In order to prevent the ultraviolet rays from the curing device 13 from irradiating the nozzles 12 and causing the nozzles 12 to be clogged, the curing device 13 and the nozzle head 11 are equidistant in the circumferential direction with the shaft member 2 interposed therebetween. It is desirable to arrange in. As the magnetizing device 16, a known configuration capable of curing the magnetic ink is selectively used according to the magnetizing pattern. In FIG. 4B, the magnetizing device 16 is arranged at the front stage of the curing device 13, but can be arranged at the rear stage of the curing device 13. If there is no particular problem, the curing device 13 and the magnetizing device 16 can be arranged at the same position in the circumferential direction.

  In the above configuration, the ink droplets 15 are ejected from the nozzles 12 while rotating the shaft member 2, and the aggregates of the ink droplets 15 are disposed on the entire circumference in the predetermined area in the axial direction of the outer peripheral surface 2 a 1 of the shaft member 2. Is covered with a resin layer 10 'having a predetermined thickness. The shaft member 2 is rotated one to several tens of times until the resin layer 10 ′ has a predetermined thickness.

  After the resin layer 10 ′ is formed, the magnetizing device 16 is activated while the shaft member 2 is held by the holding portion 14, and the resin layer 10 ′ is magnetized while rotating the shaft member 2. Thereby, as shown in FIG. 5, the magnet part 10 which has a magnetic pole is formed in the outer peripheral surface 2a1 of the axial part 2a. As shown in the enlarged sectional view of FIG. 2, the magnet part 10 has a magnetizing pattern in which the upper side of the magnet part 10 is one magnetic pole (N pole in the illustrated example) and the lower side is the other magnetic pole (in the illustrated example, In addition to the S pole, as shown in FIG. 6, the outer diameter side of the magnet portion 10 is set as one magnetic pole (N pole in the illustrated example), and the inner diameter side is set as the other magnetic pole (S pole in the illustrated example). You can also. After completion of magnetization, the shaft member 2 is further rotated, and in this state, the resin layer 10 ′ is cured by irradiating with ultraviolet rays from the curing device 13. If the shaft member 2 is removed from the holding portion 14 after the resin layer 10 'is cured, the shaft member 2 shown in FIG. 2 in which the thin ring-shaped magnet portion 10 is formed on the outer periphery of the shaft portion 2a is obtained.

  As described above, if the resin layer 10 'is printed and then magnetized before it is cured, the orientation of the magnetic material blended in the ink is increased, so that a larger magnetic force can be obtained. In addition, if there is no particular problem, the resin layer 10 ′ may be cured and then magnetized. Specifically, for example, while the shaft member 2 rotates once, the resin layer 10 ′ is printed and cured, and this cycle is repeated a plurality of times to form a resin layer 10 ′ having a predetermined thickness, and then the resin The layer 10 ′ may be magnetized.

  Although the shaft member 2 is rotationally driven in the above description, the shaft member 2 may be fixed and the nozzle head 11, the curing device 13, and the magnetizing device 16 may be rotationally driven on the outer periphery of the shaft member 2. .

  In the hydrodynamic bearing device 1 having the above-described configuration, when the shaft member 2 rotates, the regions provided separately at the two upper and lower positions serving as the radial bearing surface of the inner peripheral surface 8a of the bearing sleeve 8 are the outer peripheral surface 2a1 of the shaft member 2, respectively. And through a radial bearing gap. As the shaft member 2 rotates, the magnetic fluid film formed in the radial bearing gap is enhanced in fluid film rigidity by the dynamic pressure action of the dynamic pressure groove, and the shaft member 2 is not rotatable in the radial direction. Contact supported. 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.

  Further, when the shaft member 2 rotates, a region serving as a thrust bearing surface of the lower end surface 8c of the bearing sleeve 8 faces the upper end surface 2a1 of the flange portion 2a via a predetermined thrust bearing gap, and the bottom portion 7b of the housing 7 A region serving as a thrust bearing surface of the upper end surface 7b1 faces the lower end surface 2b2 of the flange portion 2b via a thrust bearing gap. As the shaft member 2 rotates, the magnetic fluid film formed in both thrust bearing gaps has its fluid film rigidity increased by the dynamic pressure action of the dynamic pressure grooves, and the shaft member 2 is not rotatable in both thrust directions. Contact supported. Thereby, the 1st thrust bearing part T1 and the 2nd thrust bearing part T2 which non-contact-support the shaft member 2 rotatably in both thrust directions are formed.

  As described above, in the present invention, after forming the resin layer 10 ′ composed of an aggregate of a small amount of ink containing a magnetic material, this is magnetized to form the magnet portion 10, and the magnet portion 10 and the magnetic material A magnetic circuit is formed between the seal member 9 and the seal member 9. With this configuration, since the base structure of the magnet portion 10 is ink (resin), the material cost can be reduced and the hydrodynamic bearing device 1 can be reduced in comparison with the conventional configuration in which one side forming the magnetic circuit is a sealing magnet. Cost reduction can be achieved.

  In addition, a small amount of ink aggregate forming the magnet portion 10 (resin layer 10 ′) causes the ink droplets 15 supplied from the nozzles 12 to land or drop in a non-contact manner on the outer peripheral surface 2 a 1 of the shaft member 2. It is formed by printing by an ink jet method for collecting droplets. In this printing method, since the ink supply amount and supply location can be precisely controlled by a program, programming is performed in advance, and the position of the nozzle head 11 and the ink supply / stop are controlled in accordance with the program. The magnet portion 10 having an arbitrary shape can be easily formed. Therefore, it is possible to easily form the magnet portion 10 in a thin film shape as shown in the figure, and it is not necessary to consider the installation space of the magnet, and the hydrodynamic bearing device 1 can be downsized.

  In general, a magnet (seal magnet) has low mechanical strength and may be lost when an impact load is applied due to dropping or the like. If it is made of resin, such a concern can be eliminated and a magnetic circuit having excellent reliability can be configured.

  In addition, in this embodiment, although the magnet part 10 is formed in the outer peripheral surface 2a1 of the shaft member 2, the magnet part 10 can also be formed in the inner peripheral surface of the seal member 9 as shown in FIG. In this case, if the seal member 9 is made of a nonmagnetic material and the shaft member 2 is made of a magnetic material, a magnetic circuit similar to the above is formed.

  Although one embodiment of the present invention has been described above, the present invention can be similarly applied not only to the hydrodynamic bearing device 1 shown in FIG. 2 but also to other forms of hydrodynamic bearing devices. In the following description, members and elements having basically the same functions as those in the embodiment shown in FIG.

  FIG. 8 shows another embodiment of the hydrodynamic bearing device 1. In the hydrodynamic bearing device 1 shown in the figure, a magnet portion 10 is mainly formed on the outer peripheral surfaces 9c and 19c of the seal members 9 and 19 provided on the shaft member 2, and the inner peripheral surface 7a1 of the housing 7 facing this. A magnetic circuit and seal spaces K1 and K2 (magnetic seals) are formed between them, and thrust bearing portions T1 and T2 are opposite end faces 8d and 8c of the bearing sleeve 8 and a seal member 9 that is opposed thereto. 2 is different from the configuration shown in FIG. 2 in that it is provided between 19 end faces 9b and 19b.

  FIG. 9 shows another embodiment of the hydrodynamic bearing device 1. In the hydrodynamic bearing device 1 shown in the figure, a magnet portion 10 is mainly formed on a tapered outer wall 7a3 of a housing 7, and a magnetic field is formed between the magnet portion 10 and the inner peripheral surface 3b1 of the side portion 3b of the disk hub 3 facing this. The circuit and the seal space K are provided, and the second thrust bearing portion T2 is provided between the lower end surface 3a1 of the disk hub 3 and the upper end surface 7a2 of the housing 7 in the fluid shown in FIG. The configuration is different from that of the bearing device 1.

  Even when the shape of the magnet portion 10 and the member on which the magnet portion 10 is formed are changed as in the hydrodynamic bearing device 1 shown in FIGS. 8 and 9 above, the magnet can be changed by simply changing the program, the support form of the substrate, and the like. The part 10 can be easily formed. In particular, in the hydrodynamic bearing device in which the seal space K is formed without using a seal member as shown in FIG. 9, the members (disk hub 3 and housing 7) that form the seal space are magnetized. Therefore, it is possible to eliminate the problem of high cost due to the above and the problem of the installation space of the magnet, and to employ the magnetic seal at a low cost.

  In the above description, the radial bearing portions R1 and R2 are exemplified by the configuration in which the dynamic pressure action of the lubricating oil is generated by the herringbone-shaped or spiral-shaped dynamic pressure grooves, but as the radial bearing portions R1 and R2, A so-called step bearing or multi-arc bearing can also be employed. A multi-arc bearing or a step bearing is a bearing having a configuration in which a plurality of axial grooves and arc surfaces are provided in a region serving as a radial bearing surface.

  Further, in the above description, the radial bearing portions are provided at two axial positions as in the radial bearing portions R1 and R2, but the radial bearing portions are provided at one axial location or three or more locations in the axial direction. You can also.

  Further, one or both of the thrust bearing portions T1 and T2 can be configured by, for example, a step bearing, or can be configured by a so-called wave-shaped bearing (a step-type is a wave-shaped).

  Moreover, although the form which comprises both radial bearing part R1, R2 by a dynamic pressure bearing was illustrated in the above description, one or both of radial bearing part R1, R2 can also be comprised by a perfect circle bearing.

It is sectional drawing of the spindle motor for information devices incorporating the hydrodynamic bearing apparatus. It is sectional drawing of the hydrodynamic bearing apparatus concerning this invention. (A) is a sectional view of the bearing sleeve, and (b) is a view showing a lower end surface of the bearing sleeve. (A) The figure is a side view of the manufacturing apparatus of a magnet part, (b) The figure is the same sectional drawing. It is sectional drawing of a shaft member provided with the magnet part obtained by magnetizing. It is sectional drawing which shows the other structural example of a magnetic pole. It is sectional drawing which shows other embodiment of the magnetic seal shown in FIG. It is sectional drawing which shows other embodiment of the hydrodynamic bearing apparatus. It is sectional drawing which shows other embodiment of the hydrodynamic bearing apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fluid dynamic bearing apparatus 2 Shaft member 2a Shaft part 2b Flange part 7 Housing 8 Bearing sleeve 9, 19 Seal member 10 Magnet part 10 'Resin layer 11 Nozzle head 12 Nozzle (ink supply part)
13 Curing device 14 Holding portion 15 Micro droplet 16 Magnetizing device K, K1, K2 Seal space R1, R2 Radial bearing portion T1, T2 Thrust bearing portion

Claims (3)

A rotating member, a fixing member, a magnetic fluid that fills a bearing gap formed between the two members, and a magnetic seal that prevents leakage of the magnetic fluid with a magnet provided on one of the rotating member and the fixing member, In the hydrodynamic bearing device that rotatably supports the rotating member via the magnetic fluid film formed in the bearing gap,
A hydrodynamic bearing device in which a magnet of a magnetic seal is formed by magnetizing an aggregate of a small amount of ink containing a magnetic material.   The hydrodynamic bearing device according to claim 1, wherein the ink has photocurability.   A motor comprising the hydrodynamic bearing device according to claim 1, a stator coil, and a rotor magnet.

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