JP2007155093A - Bearing mechanism, motor, recording disc drive mechanism and sleeve member manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To facilitate the manufacture of an electric motor with a bearing mechanism having upper and lower annular tapered seals while utilizing fluid dynamic pressure. <P>SOLUTION: In the bearing mechanism for the motor 1, lubricating oil is continuously filled in a filling gap among a fixed shaft 22 having a flange portion 221, an anti-come-off member 23 mounted on a stepped portion of the fixed shaft 22, and a sleeve member 31 having a hub, and the tapered seals are formed in upper and lower annular tapered gaps 44, 45 by the lubricating oil. The motor 1 has a thrust hydrodynamic bearing mechanism formed only in a lower gap 42, thus facilitating the manufacture of the sleeve member 31 of the bearing mechanism on which the upper and lower tapered seals are provided and the and assembly of the bearing mechanism when reducing the size and thickness of the motor 1. The construction of the bearing mechanism with three members facilitates the assembly of the bearing mechanism on which the upper and lower tapered seals are provided. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an electric motor, a bearing mechanism using fluid dynamic pressure provided in the motor, and a sleeve member used in the bearing mechanism.

  2. Description of the Related Art Conventionally, a recording disk drive device such as a hard disk device has been provided with a spindle motor (hereinafter referred to as “motor”) that rotationally drives the recording disk, and uses fluid dynamic pressure as one of the motor bearing mechanisms. A bearing mechanism is adopted. In such a bearing mechanism using fluid dynamic pressure, in many cases, a thrust dynamic pressure bearing mechanism and a radial dynamic pressure bearing mechanism are configured between a shaft or a portion connected to the shaft and a sleeve into which the shaft is inserted. Is done.

  Patent Document 1 discloses a bearing mechanism in which a shaft is inserted into a sleeve in which an inner sleeve and an outer sleeve are combined, and a radial bearing is formed between the outer peripheral surface of the shaft and the inner peripheral surface of the inner sleeve. Thrust bearings are respectively formed on the upper end surface and the lower end surface of the inner sleeve. Further, a flow path that communicates vertically is provided between the inner sleeve and the outer sleeve, and a shaft that faces the upper end surface of the inner sleeve and the outer sleeve, and a shaft that faces the lower end surface of the inner sleeve. An annular taper seal is formed between the flange portion and the outer sleeve. Patent Document 2 discloses a structure in which the inner rotor and the outer rotor of Patent Document 1 are integrated.

On the other hand, the thrust dynamic pressure bearing mechanism may be provided on one side of the upper and lower end surfaces of the sleeve. In this case, the sleeve is magnetically biased toward the thrust dynamic pressure bearing mechanism. Examples of such a bearing mechanism include those disclosed in Patent Documents 3 and 4.
JP 2005-48890 A JP 2002-70849 A Japanese Patent No. 3155529 US Pat. No. 6,917,130

  In recent years, recording disk drive devices are also mounted on mobile phones, portable music players, etc., and there is a demand for small and thin recording disk drive devices. Therefore, the same applies to motors that are drive sources of recording disk drive devices. Further downsizing and thinning are required. In the case of a motor used in a recording disk drive apparatus of 1 inch or less, a moment acts on the rotor due to a load caused by a reaction force from the head suspension when the head enters. When contact occurs between members constituting the bearing mechanism due to the moment, abnormal vibration due to contact occurs, and reading / writing becomes impossible. For this reason, contact within the bearing is not caused by the moment, and it is also required to reduce power loss by reducing the loss of the bearing mechanism.

  By the way, as in Patent Document 1, in order to provide the thrust dynamic pressure bearing mechanism at two locations on the upper and lower sides of the sleeve, it is necessary to strictly manage the dimension between the upper and lower surfaces of the sleeve. However, when the motor is extremely reduced in size and thickness, such highly accurate processing and assembly becomes difficult. In addition, when two thrust dynamic pressure bearing mechanisms are provided, energy loss due to the entire bearing mechanism also increases. Furthermore, in the motor of Patent Document 1, it is also necessary to strictly control the position adjustment of this member when attaching the retaining member to the shaft.

  In addition, if the rotor side is constituted by members such as an inner sleeve, an outer sleeve, and a hub body, the assembly work must be complicated due to the miniaturization and thinning of the motor.

  The present invention has been made in view of the above problems, and has as its main purpose to facilitate the manufacture of a bearing mechanism employed in a small and thin motor and such a motor.

  The invention according to claim 1 is a bearing mechanism using fluid dynamic pressure used in an electric motor, wherein one end is fixed at a predetermined mounting position, and the flange portion extends outward from the central axis on the one end side. A fixed shaft having a stepped portion with a reduced diameter on the other end side, a sleeve member inserted into the fixed shaft and having one end surface facing the flange portion, and the stepped portion of the fixed shaft. An annular retaining member that is attached and faces the other end surface of the sleeve member; and a biasing mechanism that biases the sleeve member toward the flange portion in a non-contact manner by a magnetic action, and the fixed shaft A radial dynamic pressure bearing mechanism is formed between the sleeve member and the inner peripheral surface of the sleeve member, and a thrust dynamic pressure bearing mechanism is formed between the one end surface of the sleeve member and the flange portion. The member includes a first annular protrusion that protrudes from the one end surface and covers the outer peripheral surface of the flange portion, and a second annular protrusion that protrudes from the other end surface and covers the outer peripheral surface of the retaining member, As the filling oil between the fixed shaft, the retaining member, and the sleeve member is continuously filled with lubricating oil, the distance from the one end surface of the sleeve member increases between the flange portion and the first annular projecting portion. A first taper gap that gradually increases is formed, and a second taper gap that gradually increases as the distance from the other end surface of the sleeve member increases between the retaining member and the second annular protrusion, and the first taper gap is formed. A taper seal is formed in the taper gap and the second taper gap by the lubricating oil continuing from the filling gap.

  The invention according to claim 2 is a bearing mechanism using fluid dynamic pressure used in an electric motor, wherein one end is fixed at a predetermined mounting position, and the flange portion extends outward from the central axis on the one end side. A fixed shaft having a step portion with a reduced diameter on the other end side, a sleeve member inserted into the fixed shaft and having one end surface facing the flange portion, and the step portion of the fixed shaft. And an annular retaining member facing the other end surface of the sleeve member, and a radial dynamic pressure bearing mechanism is formed between the fixed shaft and the inner peripheral surface of the sleeve member. A thrust hydrodynamic bearing mechanism is formed between at least one end surface and the flange portion and between the other end surface of the sleeve member and the retaining member, and the sleeve member A first annular projecting portion projecting from the one end surface and covering the outer peripheral surface of the flange portion; and a second annular projecting portion projecting from the other end surface and covering the outer peripheral surface of the retaining member; Lubricating oil is continuously filled in the filling gap between the retaining member and the sleeve member, and gradually expands as the distance from the one end surface of the sleeve member increases between the flange portion and the first annular projecting portion. A first taper gap is formed, and a second taper gap is formed between the retaining member and the second annular protrusion, the second taper gap gradually expanding as the distance from the other end surface of the sleeve member increases. A taper seal is formed in the second taper gap by the lubricating oil continuous from the filling gap, and the sleeve member serves as a hub to which a field magnet is attached. , The fixed shaft, the sleeve member, and each of said retaining member is formed as a single member.

  A third aspect of the present invention is the bearing mechanism according to the second aspect, wherein a thrust dynamic pressure bearing mechanism is formed only between the one end surface of the sleeve member and the flange portion.

  The invention according to claim 4 is the bearing mechanism according to claim 1 or 3, wherein the dynamic pressure groove of the radial dynamic pressure bearing mechanism is a herringbone groove, and the other end face side of the herringbone groove The pressure generated at the part is higher than the pressure generated at the one end face side part.

  The invention according to claim 5 is the bearing mechanism according to claim 1, 3 or 4, wherein the dynamic pressure groove of the thrust dynamic pressure bearing mechanism is a herringbone groove, and the first of the herringbone grooves is the first. The pressure generated at the portion on the annular protrusion side is higher than the pressure generated at the portion on the fixed shaft side.

  A sixth aspect of the present invention is the bearing mechanism according to any one of the first and third to fifth aspects, wherein the sleeve member removes the lubricating oil from the outer peripheral side of the flange portion. A circulation hole leading to the outer peripheral side is provided.

  A seventh aspect of the present invention is the bearing mechanism according to the sixth aspect, wherein the retaining member moves radially outward on a surface facing the other end surface of the sleeve member while the sleeve member faces the other end surface. A stirring groove is provided in a direction opposite to the rotation direction.

  The invention according to claim 8 is the bearing mechanism according to any one of claims 1 and 3 to 7, wherein the gap between the other end surface of the sleeve member and the retaining member is a diameter. A tapered portion that gradually increases toward the outside in the direction is provided.

  The invention according to claim 9 is the bearing mechanism according to claim 8, wherein the sleeve member protrudes closer to the retaining member than the tapered portion around the fixed shaft on the other end surface. Protrusions are provided.

  The invention according to claim 10 is the bearing mechanism according to claim 2, wherein the thrust dynamic pressure bearing mechanism is formed only between the other end surface of the sleeve member and the retaining member.

  Invention of Claim 11 is a bearing mechanism of Claim 10, Comprising: The dynamic pressure groove of the said radial dynamic pressure bearing mechanism is a herringbone groove, The site | part of the said one end surface side of the said herringbone groove Is higher than the pressure generated at the other end surface portion.

  The invention according to claim 12 is the bearing mechanism according to claim 10 or 11, wherein the dynamic pressure groove of the thrust dynamic pressure bearing mechanism is a herringbone groove, and the second annular protrusion of the herringbone groove. The pressure generated at the portion side portion is higher than the pressure generated at the fixed shaft side portion.

  A thirteenth aspect of the present invention is the bearing mechanism according to any one of the tenth to twelfth aspects, wherein the sleeve member moves the lubricating oil from the outer peripheral side of the retaining member to the outer peripheral side of the flange portion. It has a circulation hole to guide.

  A fourteenth aspect of the present invention is the bearing mechanism according to any one of the first and third to thirteenth aspects, wherein the gap of the radial dynamic pressure bearing mechanism and the gap of the thrust dynamic pressure bearing mechanism are reduced. Of the width and the width of the thrust gap on the opposite side of the sleeve member from the thrust dynamic pressure bearing mechanism, the radial dynamic pressure bearing mechanism has the smallest gap width and the thrust gap width is the largest.

  The invention according to claim 15 is an electric motor, wherein the bearing mechanism according to any one of claims 1 to 14, a base portion to which the one end of the fixed shaft is fixed, an armature, A field magnet that is attached to the sleeve member and generates torque about a predetermined central axis with the armature;

  A sixteenth aspect of the present invention is a recording disk driving device, wherein the recording disk records information, the motor according to the fifteenth aspect rotates the recording disk, and reading and / or information from the recording disk. A head unit that performs writing; and a head unit moving mechanism that moves the head unit relative to the recording disk and the motor.

  The invention according to claim 17 is a method of manufacturing a sleeve member into which a fixed shaft of a motor having a bearing mechanism using fluid dynamic pressure is inserted, and a) processing in which a hole having an opening is formed on one end side. Preparing the other end of the target original member while being held by a holding portion that rotates relative to the tool about a predetermined central axis from the one end toward the other end; b) By cutting a part of the inner peripheral surface of the hole in an annular shape centering on the central axis while the original member is held by the holding portion, the part is perpendicular to the central axis and faces the other end side Forming the first thrust portion as an inner surface of the annular groove; c) cutting the inner peripheral surface of the hole in a state where the original member is held by the holding portion, thereby reducing the diameter of the hole. D) a predetermined diameter centered on the central axis; Forming a second thrust part perpendicular to the central axis by cutting the one end side in a state where the original member is held by the holding part; e) the first thrust part and the second thrust And a step of obtaining a sleeve member having a portion by cutting the original member, wherein at least one of the first thrust portion and the second thrust portion is used for rotation of the sleeve member. It is.

  The invention according to claim 18 is the method for manufacturing a sleeve member according to claim 17, wherein, in the step c), a radial dynamic pressure surface used for rotation of the sleeve member is formed on the inner peripheral surface of the hole. It is formed.

  The invention according to claim 19 is the method of manufacturing a sleeve member according to claim 17 or 18, wherein the original member is moved to the first member after the step d) and before the step e). The method further includes a step of holding from the side of the two thrust portions.

  A twentieth aspect of the invention is the method for manufacturing a sleeve member according to any one of the seventeenth to nineteenth aspects, wherein the sleeve member is a hub to which a field magnet is attached.

  In the first, third, and tenth aspects of the invention, it is possible to easily manufacture a bearing mechanism having an annular tapered seal on both end surfaces of the sleeve member. Further, in the invention of claim 2, the bearing mechanism can be obtained by reducing the number of parts of the bearing mechanism having the annular taper seals on both end surfaces of the sleeve member and inserting the sleeve member and the retaining member into the fixed shaft in order. Can be easily manufactured. In particular, in the present invention, even a small and thin motor can facilitate the manufacture of the bearing mechanism and the motor.

  According to the fourth, fifth, eleventh and twelfth aspects of the present invention, it is possible to suppress the generation of negative pressure of the lubricating oil in the region on the fixed shaft side of the thrust dynamic pressure bearing mechanism when the bearing mechanism rotates. In the inventions of claims 6 and 13, the pressure difference of the lubricating oil at both end faces of the sleeve member can be suppressed and the generated bubbles can be discharged to the outside of the bearing mechanism through the taper seal. Then, the generation of negative pressure in the region on the fixed shaft side of the thrust gap can be prevented by the dynamic pressure generated by the stirring groove.

  In the invention of claim 8, by reducing the pressure outside the inner side in the radial direction, the bubbles are easily discharged to the outside of the bearing mechanism through the taper seal. In the invention of claim 9, in the direction of the central axis of the sleeve member Can be determined with high accuracy.

  In the invention of claim 17, the accuracy of the distance between the first thrust part and the second thrust part can be easily improved, and in the invention of claim 18, the radial dynamic pressure surface can be easily formed. Further, in the invention of claim 19, many parts can be processed at one time, and in the invention of claim 20, the number of parts of the bearing mechanism can be reduced and the bearing mechanism can be easily manufactured.

  FIG. 1 is a diagram showing an internal configuration of a recording disk drive device 60 including an electric spindle motor 1 (hereinafter referred to as “motor 1”) according to a first embodiment of the present invention. The recording disk drive device 60 is a so-called hard disk device, and rotates while holding a disk-shaped recording disk 62 for recording information, an access unit 63 for reading and / or writing information to the recording disk 62, and the recording disk 62. An electric motor 1 and a housing 61 for housing the recording disk 62, the access unit 63, and the motor 1 in the internal space 110 are provided.

  As shown in FIG. 1, the housing 61 has an opening in the upper part and an opening of the first housing member 611 having a lidless box shape to which the motor 1 and the access unit 63 are attached to the inner bottom surface, and the opening of the first housing member 611. A plate-like second housing member 612 that forms the internal space 110 by covering the plate is provided. In the recording disk drive device 60, the second housing member 612 is joined to the first housing member 611 to form the housing 61, and the internal space 110 is a clean space that is extremely free of dust and dirt.

  The recording disk 62 is placed on the upper side of the motor 1 and is fixed to the motor 1 by the clamper 621. The access unit 63 includes a head 631 close to the recording disk 62 and an arm 632 that supports the head 631 as a head unit, and reading and / or writing of information is magnetically performed by the head unit. The access unit 63 includes a head unit moving mechanism 633 that moves the head 631 relative to the recording disk 62 and the motor 1 by moving the arm 632. With these configurations, the head 631 accesses a required position of the recording disk 62 in the state of being close to the rotating recording disk 62, and reads and / or writes information.

  FIG. 2 is a longitudinal sectional view showing a configuration of the motor 1 used for rotating the recording disk 62 (see FIG. 1). In FIG. 2, although the longitudinal cross section in the surface containing the central axis J1 of the motor 1 is shown, also about the structure located in the back | inner side rather than a cut surface, the part is drawn with the broken line. As shown in FIG. 2, the motor 1 includes a stator portion 2 that is a fixed assembly and a rotor portion 3 that is a rotating assembly, and the rotor portion 3 is a bearing that uses fluid dynamic pressure by lubricating oil. Via the mechanism 10 (consisting of a fixed shaft 22, a sleeve member 31 and a retaining member 23, which will be described later), the stator portion 2 is supported rotatably about the central axis J1. In the following description, for convenience, the rotor part 3 side is described as the upper side and the stator part 2 side is the lower side along the central axis J1, but the central axis J1 does not necessarily coincide with the direction of gravity.

  The stator part 2 includes a base plate 21 that is a base part for holding each part of the stator part 2, and a fixed shaft 22 having a step part 222 whose one end is fixed to a predetermined mounting position of the base plate 21 and whose diameter is reduced on the other end side. An annular retaining member 23 attached to the step 222 of the fixed shaft 22, an armature 24 attached to the base plate 21, and a thin plate-like shape disposed above the armature 24 to block electromagnetic noise from the armature 24. A magnetic shield plate 25 is provided. The base plate 21 is a part of the first housing member 611 (see FIG. 1), and the first housing member 611 is pressed by pressing a plate member made of aluminum, an aluminum alloy, or a magnetic or nonmagnetic iron-based metal. It is formed integrally with other parts.

  The fixed shaft 22 further includes a flange portion 221 that extends outward from the central axis J1 on one end side (lower end side) fixed to the base plate 21, and a through hole 223 that penetrates along the central axis J1 is formed in the fixed shaft 22. It is formed. A female screw for screwing the second housing member 612 (see FIG. 1) is formed in the upper portion of the through hole 223. The lower part of the through hole 223 is sealed by a substantially spherical metal sealing member 26. The fixed shaft 22 and the retaining member 23 are made of stainless steel, free-cutting stainless steel, or the like.

  In the motor 1, the flange portion 221 is integrally provided on the fixed shaft 22 as a part of the fixed shaft 22. Thereby, compared with the case where the fixed shaft 22 and the flange part 221 are formed by separate members, a high-accuracy squareness can be given between the upper surface of the flange part 221 and the central axis J1, and the flange part A strong fastening strength can be obtained between 221 and the main portion of the fixed shaft 22. Further, the bearing mechanism 10 and the motor 1 can be made thin with respect to the direction of the central axis J1.

  The armature 24 is attached to the base plate 21 from above by press-fitting or bonding, and includes a core 241 formed by laminating a plurality of (in this embodiment, five) core plates formed of thin silicon steel plates. The core 241 supports a plurality of teeth 243 radially arranged around the central axis J1 and the plurality of teeth 243 from the outside (that is, connects the ends of the teeth 243 far from the central axis J1). A ring-shaped core back. The thickness of each of the core plates forming the core 241 is 0.1 to 0.35 mm, and preferably 0.2 mm. In each core plate, the portions corresponding to each of the plurality of teeth 243 and the core back are integrally formed, so that the plurality of teeth 243 and the core back are magnetically connected.

  The armature 24 includes a plurality of coils 242 formed by winding a conductive wire having a diameter of 0.05 to 0.3 mm (more preferably 0.1 mm) around each of the plurality of teeth 243 of the core 241 in multiple layers. Further prepare.

  The rotor portion 3 is inserted into the fixed shaft 22 of the stator portion 2 with a slight gap and is a part of a bearing mechanism 10 that rotatably supports the rotor portion 3, and a substantially cylindrical sleeve member 31; A field magnet 32 is provided which is attached to the sleeve member 31 and arranged around the central axis J1. The sleeve member 31 is made of stainless steel, free-cutting stainless steel, aluminum, aluminum alloy, copper, phosphor bronze, or the like, and is formed in a substantially cylindrical shape centered on the central axis J1, and serves as a sleeve. One end face (hereinafter referred to as “lower end face”) 311 is opposed to the flange portion 221 of the fixed shaft 22 and the other end face (hereinafter referred to as “upper end face”) 312 serving as a sleeve. It faces the retaining member 23. The field magnet 32 generates torque (that is, rotational force) centered on the central axis J <b> 1 with the armature 24.

  FIG. 3 is a longitudinal sectional view showing the sleeve member 31, and FIG. 4 is a bottom view showing only the lower end surface 311 of the sleeve member 31. 2 and 3, the sleeve member 31 protrudes from the lower end surface 311 and covers the outer peripheral surface of the flange portion 221 of the fixed shaft 22. The sleeve member 31 protrudes from the upper end surface 312 and protrudes from the upper end surface 312. As shown in FIGS. 3 and 4, the second annular protrusion 314 that covers the outer peripheral surface, and two circulation holes 318 that communicate the lower end surface 311 and the upper end surface 312 are provided.

  As shown in FIG. 3, the sleeve member 31 further includes a disk portion 315 to which a field magnet 32 (see FIG. 2) is attached, forming a so-called hub. When the members constituting the bearing mechanism 10 are extremely small, if the sleeve and the hub are formed as separate members, the sleeve inner peripheral surface may be distorted when the sleeve is press-fitted into the hub. By forming the sleeve and the hub as a single member, the number of parts can be reduced and the coaxiality between the sleeve and the hub can be improved. Thus, the structure of the motor 1 is particularly suitable for downsizing.

  Next, the bearing mechanism 10 using the fluid dynamic pressure that supports the rotor portion 3 of the motor 1 to be rotatable with respect to the stator portion 2 will be described. FIG. A is a longitudinal sectional view showing a part of the motor 1 (the right half in FIG. 2) in an enlarged manner. In addition, FIG. In A, parallel oblique lines indicating a cross section of the sleeve member 31 are omitted, and two herringbone grooves 316 and 317 described later formed in the sleeve member 31 are indicated by a symbol of a chevron pattern on the sleeve member 31 side. (The same applies to FIGS. 8 and 10).

  FIG. As shown in A, in the motor 1, between the outer peripheral surface of the fixed shaft 22 and the inner peripheral surface of the sleeve member 31, between the lower end surface 311 of the sleeve member 31 and the flange portion 221 of the fixed shaft 22, and the sleeve A minute gap is provided between the upper end surface 312 of the member 31 and the retaining member 23. Hereinafter, these gaps are referred to as “side gap 41”, “lower gap 42”, and “upper gap 43”, respectively.

  The outer peripheral surface of the flange portion 221 is an inclined surface whose outer diameter gradually decreases toward the lower side, and gradually increases as the distance from the lower end surface 311 of the sleeve member 31 increases between the flange portion 221 and the first annular projecting portion 313. An expanding first taper gap 44 is formed. On the other hand, the outer peripheral surface of the retaining member 23 is an inclined surface whose outer diameter gradually decreases toward the upper side, and is separated from the upper end surface 312 of the sleeve member 31 between the retaining member 23 and the second annular projecting portion 314. A second taper gap 45 that gradually increases is formed.

  In the motor 1, a lubricating mechanism as a working fluid is continuously filled in the circulation hole 318 and the plurality of gaps (hereinafter referred to as “filling gaps”), thereby forming a so-called full-fill bearing mechanism. In the first taper gap 44 and the second taper gap 45, the interface of the lubricating oil continuing from the filling gap becomes a meniscus shape by capillary action and surface tension to form a taper seal, and the first taper gap 44 and the second taper gap 45 are formed. Plays a role as an oil buffer to prevent outflow of lubricating oil. In the motor 1, since the oil buffer has a visible structure, the lubricating oil can be easily injected and inspected.

  On the inner peripheral surface of the sleeve member 31, pressure (indicated by an arrow 52) generated at a portion on the upper end surface 312 side when the rotor portion 3 rotates (indicated by an arrow 52) is generated at a portion on the lower end surface 311 side (arrow 51). And a dynamic pressure groove for generating a higher dynamic pressure in the lubricating oil is provided, and a radial dynamic pressure bearing mechanism is formed in the side gap 41. Further, on the lower end surface 311 of the sleeve member 31, pressure (indicated by an arrow 54) generated at the site on the first annular projecting portion 313 side when the rotor unit 3 rotates is generated at the site on the fixed shaft 22 side. A dynamic pressure groove that generates a dynamic pressure higher than the pressure (indicated by an arrow 53) in the lubricating oil is provided, and a thrust dynamic pressure bearing mechanism is formed in the lower gap. The width of the gap of the radial dynamic pressure bearing mechanism (namely, the width of the side gap 41), the width of the gap of the thrust dynamic pressure bearing mechanism (namely, the width of the lower gap 42), the thrust dynamic pressure bearing mechanism of the sleeve member 31 Among the widths of the thrust gap on the opposite side (that is, the width of the upper gap 43), the radial dynamic pressure bearing mechanism has the smallest gap width and the largest thrust gap width. Specifically, the gap width of the radial dynamic pressure bearing mechanism is set to 2 to 4 μm, the gap width of the thrust dynamic pressure bearing mechanism is set to 5 to 8 μm, and the width of the upper thrust gap is set to 20 to 32 μm. .

  In the motor 1, FIG. 3 and FIG. As shown in A, the dynamic pressure groove of the radial dynamic pressure bearing mechanism provided on the inner peripheral surface of the sleeve member 31 is a herringbone groove 316 formed in a V shape that opens in the rotation direction of the sleeve member 31. Since the herringbone groove 316 has a shape in which the portion above the bent portion 3161 is longer than the portion below, the herringbone groove 316 is slightly below the center of the side gap 41 when the rotor portion 3 rotates. Lubricating oil is pushed downward in the direction of the central axis J1 (that is, in the direction of the arrow 52) by the amount that the pressure generated in the lubricating oil becomes maximum and is offset. 4 and 5. As shown in A, the dynamic pressure groove of the thrust dynamic pressure bearing mechanism is a herringbone groove 317 formed in a V shape that opens toward the rotation direction of the sleeve member 31 (that is, the rotation direction of the rotor portion 3) 71. In addition, the herringbone groove 317 is formed in a deviated shape in which the portion outside the bent portion 3171 is longer than the inside portion, so that when the rotor portion 3 rotates, the herringbone groove 317 is lubricated slightly inside from the approximate center of the lower gap 42. Lubricating oil is pushed inward in the radial direction (that is, in the direction of the arrow 54) by the amount in which the pressure generated in the oil becomes maximum and is biased.

  By these dynamic pressure bearing mechanisms, the negative pressure of the lubricating oil in the region on the fixed shaft 22 side of the thrust dynamic pressure bearing mechanism can be suppressed when the rotor portion 3 is rotated by the bearing mechanism, and bubbles are generated due to the negative pressure. In addition, abnormal vibration and seizure due to bubbles can be prevented.

  As described above, in the motor 1, the filling gap formed between the fixed shaft 22, the retaining member 23 and the sleeve member 31 (that is, the side gap 41, the lower gap 42, the upper gap 43, the first taper gap 44, and the first taper gap 44). 2 taper gap 45) and the two circulation holes 318 formed in the sleeve member 31 are continuously filled with lubricating oil, and when the rotor part 3 rotates, the rotor part 3 utilizes fluid dynamic pressure due to the lubricating oil. Is supported. Then, the recording disk 62 (see FIG. 1) attached to the rotor unit 3 rotates as the rotor unit 3 rotates with respect to the stator unit 2 about the central axis J1.

  In the motor 1, since the thrust dynamic pressure bearing mechanism is formed only in the lower gap 42, the sleeve member 31 is not contacted with the flange portion 221 by a magnetic action generated between the base plate 21 and the field magnet 32. It has come to be urged towards. That is, the field magnet 32 and the base plate 21 also serve as a biasing mechanism that biases the sleeve member 31. Thereby, when the rotor part 3 rotates, the rotor part 3 is stably supported in the thrust direction in cooperation with the levitation force and the magnetic action of the thrust dynamic pressure bearing mechanism. When the base plate 21 is formed of a non-magnetic material, the magnetic material is disposed at a position facing the field magnet 32 of the base plate 21. As another example of the urging mechanism, the magnetic center in the direction of the central axis J1 of the armature 24 (see FIG. 2) is shifted magnetically to the base plate 21 side from the magnetic center of the field magnet 32. It may be one that generates an action.

  FIG. B is shown in FIG. A region C1 on the outer peripheral side of the upper gap 43 shown in A and region C2 on the inner peripheral side of the upper gap 43 relative to the region C6 on the outer peripheral side of the lower gap 42, a region C3 facing the bent portion 3161 of the side gap 41, and the lower gap 42 is a diagram showing the relative level of pressure generated in the lubricating oil in each region of a region C4 on the inner peripheral side of 42 and a region C5 facing the bent portion 3171 of the lower gap 42. FIG. In the motor 1, FIG. A and FIG. As shown in B, the pressure generated in the lubricating oil in the region C3 is higher than the pressure in the region C5, and the lubricating oil pushed downward in the central axis J1 direction (that is, in the direction of the arrow 52) in the side gap 41 is The lower gap 42, the circulation hole 318, and the upper gap 43 are returned to the side gap 41 to form a lubricating oil circulation path indicated by an arrow 55. In other words, the circulation hole 318 guides the lubricating oil from the outer peripheral side of the flange portion 221 to the outer peripheral side of the retaining member 23, thereby being used for the circulation of the lubricating oil in the bearing mechanism of the motor 1. As a result, the pressure difference of the lubricating oil at both end faces of the sleeve member 31 is suppressed, and even if bubbles are generated in the lubricating oil, the generated bubbles are removed from the first taper gap 44 and the second taper. It can be discharged to the outside of the bearing mechanism through the taper seal of the gap 45.

  FIG. 6 is a bottom view showing the retaining member 23. As shown in FIG. 6, the retaining member 23 includes four agitation grooves 231 that agitate the lubricating oil on a surface facing the upper end surface 312 of the sleeve member 31 (that is, the lower surface of the retaining member 23). The stirring groove 231 is a spiral groove that faces the outer side in the radial direction and goes in a direction opposite to the rotation direction 71 of the sleeve member 31. As a result, the lubricating oil is pushed inward in the radial direction of the upper gap 43 (see FIG. 5A) by the pressure generated by the stirring groove 231 when the rotor portion 3 rotates, and in the region of the upper gap 43 on the fixed shaft 22 side. Generation of negative pressure can be prevented.

  FIG. 7 is an enlarged longitudinal sectional view showing the upper gap 43. On the upper end surface 312 of the sleeve member 31, as shown in FIG. 7, a tapered portion 3121 is formed in which the gap (that is, the upper gap 43) with the retaining member 23 gradually increases toward the outside in the radial direction. By lowering the pressure outside the radially inner side of the upper gap 43, bubbles existing in the upper gap 43 or bubbles moving to the upper opening of the circulation hole 318 are passed through the taper seal in the second taper gap 45. It becomes easy to be discharged outside the bearing. Further, the sleeve member 31 includes a protruding portion 3122 that protrudes toward the retaining member 23 with respect to the tapered portion 3121 around the fixed shaft 22 on the upper end surface 312. Even if the sleeve member 31 is lifted upward, the protruding portion 3122 is a part that abuts against the retaining member 23 and prevents the sleeve member 31 from moving, and the dimension between the lower end surface 311 and the protruding portion 3122 is highly accurate. Is done. Thereby, the attachment position of the central axis J1 direction of the sleeve member 31 can be determined with high accuracy.

  As described above, in the motor 1, the step portion 222 is formed on the fixed shaft 22, and the positioning of the retaining member 23 is completed only by abutting against the step portion 222. The bearing mechanism can be easily assembled by simply inserting the retaining member 23 in order.

  Further, since an annular taper seal is provided on the outer circumference of the thrust dynamic pressure bearing mechanism (lower gap 42) and the outer circumference of the thrust gap (upper gap 43), in other words, on both end surfaces of the sleeve member 31, the bearing mechanism The height in the direction of the central axis J1 can be kept low. In the motor 1 having such a structure, each of the fixed shaft 22, the retaining member 23, and the sleeve member 31 is formed as one member, that is, mainly one type of material (for example, an alloy, ceramics, or resin). Therefore, the bearing mechanism can be constituted by three members, and the number of parts can be reduced to facilitate the assembly.

  Further, in the motor 1, since the thrust dynamic pressure bearing mechanism is not formed in the upper gap 43, it is not necessary to strictly control the accuracy of the upper gap 43. Therefore, the bearing mechanism has annular taper seals on both end faces of the sleeve member 31. (Especially the sleeve member 31) can be manufactured easily, and the defect rate at the time of manufacturing the motor 1 can be reduced. Furthermore, since the gap dimension is formed large in a wide range of the upper gap 43, energy loss in the bearing mechanism due to an increase in pressure generated in the lubricating oil can be suppressed, and an increase in power consumption can be suppressed.

  In particular, the manufacture of the bearing mechanism and the motor 1 can be facilitated even with a small and thin motor.

  Next, a motor 1a according to a second embodiment of the present invention will be described. FIG. 8 is an enlarged longitudinal sectional view showing a part of the motor 1a. As in the first embodiment, the motor 1a is an electric motor used to rotate the recording disk of the recording disk drive apparatus. As shown in FIG. Instead of the sleeve member 31 of the motor 1 shown in A, the sleeve member 31 includes a sleeve member 31a having a different structure, and is substantially the same as the motor 1 except that the stirring groove 231 is omitted from the retaining member 23. Similar components are denoted by the same reference numerals in the following description.

  On the inner peripheral surface of the sleeve member 31a, pressure generated at a portion on the lower end surface 311 side (indicated by an arrow 51) and pressure generated at a portion on the upper end surface 312a side (arrow 52) when the rotor portion 3 rotates. Herringbone groove 316a for generating a dynamic pressure equal to that in the lubricating oil is provided, and a radial dynamic pressure bearing mechanism is formed in the side gap 41. The lower end surface 311 of the sleeve member 31a is provided with a herringbone groove 317 for generating the dynamic pressure indicated by the arrows 53 and 54 in the lubricating oil in the same manner as the motor 1, and a thrust dynamic pressure bearing mechanism is formed in the lower gap 42. Is done.

  FIG. 9 is a plan view showing only the upper end surface 312a of the sleeve member 31a. On the upper end surface 312a of the sleeve member 31a, the tapered portion 3121 and the projection 3122 of the sleeve member 31 shown in FIG. 7 are not formed, and a herringbone groove 317a is provided as shown in FIGS. Also, a thrust dynamic pressure bearing mechanism is formed. When the rotor portion 3 rotates in the rotation direction 71 between the upper end surface 312a of the sleeve member 31a and the retaining member 23 (that is, the upper gap 43) by the herringbone groove 317a, the second annular protrusion 314 side A dynamic pressure is generated in the lubricating oil that is higher than the pressure (indicated by arrow 53a) generated in the portion on the fixed shaft 22 side (indicated by arrow 54a).

  In the motor 1a, the thrust dynamic pressure bearing mechanism for pushing the lubricating oil to the inner peripheral side is formed in both the lower gap 42 and the upper gap 43, so that the inner circumferences of the lower gap 42 and the upper gap 43 are rotated when the rotor unit 3 rotates. The negative pressure of the lubricating oil on the side can be suppressed to suppress the generation of bubbles due to the negative pressure, the rigidity against the moment due to the head suspension load when the recording disk drive enters the head is improved, and abnormal vibration due to bearing contact Can be suppressed. When two thrust hydrodynamic bearing mechanisms are formed on the sleeve member 31a, the pressure generated in the lubricating oil increases and energy loss in the bearing mechanism increases, but the magnetic material cancels on the lower surface of the field magnet 32. By reducing the eddy current generated in the base plate 21 by attaching the plate 33, energy loss in the bearing mechanism can be compensated.

  In the motor 1a, the sleeve member 31a is formed with a circulation hole 318 that allows the lower gap 42 and the upper gap 43 to communicate with each other, and the pressure generated in the lubricating oil in the lower gap 42 and the upper gap 43 when the rotor portion 3 rotates. Since they are substantially equal, the pressure of the lubricating oil is prevented from increasing in either one of the two gaps, and the sleeve member 31a is prevented from being excessively biased upward or downward. Further, since each of the fixed shaft 22, the retaining member 23, and the sleeve member 31a is formed as one member, a bearing mechanism can be configured by three members, and the number of components can be reduced to reduce the number of parts. Assembly can be facilitated. It is also possible to easily assemble the bearing mechanism by simply inserting the sleeve member 31 a into the fixed shaft 22 and inserting the retaining member 23 up to the stepped portion 222.

  Next, a motor 1b according to a third embodiment of the present invention will be described. FIG. 10 is an enlarged longitudinal sectional view showing a part of the motor 1b. As shown in FIG. 10, the motor 1b is substantially the same as the motor 1a except that a sleeve member 31b having a different structure from the sleeve member 31a is provided instead of the sleeve member 31a of the motor 1a shown in FIG. In the following description, the same components are denoted by the same reference numerals.

  On the inner peripheral surface of the sleeve member 31b, pressure (indicated by an arrow 51) generated at a portion on the lower end surface 311a side when the rotor portion 3 rotates (indicated by an arrow 51) is generated at a portion on the upper end surface 312a side (arrow 52). Herringbone groove 316b for generating a higher dynamic pressure in the lubricating oil is provided, and a radial dynamic pressure bearing mechanism is formed in the side gap 41.

  Similar to the upper end surface 312a of the sleeve member 31a shown in FIGS. 8 and 9, the upper end surface 312a of the sleeve member 31b is located in the upper gap 43 at a portion on the second annular projecting portion 314 side when the rotor portion 3 rotates. A herringbone groove 317a is provided for generating a dynamic pressure in the lubricant that is higher than the pressure (indicated by arrow 53a) generated at the portion on the fixed shaft 22 side (indicated by arrow 54a). A thrust dynamic pressure bearing mechanism is formed in the upper gap 43. Thereby, when the rotor part 3 is rotated by the bearing mechanism, it is possible to suppress the negative pressure of the lubricating oil in the region on the fixed shaft 22 side of the upper gap 43 and to suppress the generation of bubbles due to the negative pressure. In addition, the dynamic pressure groove is not provided in the lower end surface 311a of the sleeve member 31b.

  In the motor 1b, the width of the gap of the radial dynamic pressure bearing mechanism (ie, the width of the side gap 41), the width of the gap of the thrust dynamic pressure bearing mechanism (ie, the width of the upper gap 43), and the thrust dynamic pressure of the sleeve member 31b. Of the width of the thrust gap on the opposite side to the bearing mechanism (that is, the width of the lower gap 42), the radial dynamic pressure bearing mechanism has the smallest gap width and the largest thrust gap width. For this reason, strict precision control in the lower gap 42 of the motor 1b is not required, the assembly of the bearing mechanism can be easily performed, and the defect rate at the time of manufacturing the motor 1b can be reduced.

  Further, since the thrust dynamic pressure bearing mechanism is formed only in the upper gap 43, energy loss in the bearing mechanism due to an increase in pressure applied to the lubricating oil can be suppressed, and an increase in power consumption can be suppressed. Further, the motor 1b is provided with an urging mechanism that stably supports the rotor portion 3 from the thrust direction in cooperation with the dynamic pressure generated by the thrust dynamic pressure bearing mechanism. The urging mechanism may be one that generates a magnetic action by shifting the magnetic center of the armature 24 in the direction of the central axis J1 above the magnetic center of the field magnet 32. The base plate 21 and the sleeve member A member that generates a magnetic repulsive force between 31b and 31b may be disposed as an urging mechanism.

  In the motor 1b, a circulation hole 318 for guiding lubricating oil from the outer peripheral side of the retaining member 23 to the outer peripheral side of the flange portion 221 is formed in the sleeve member 31b, and as shown in FIG. The lubricating oil pushed upward in the direction (that is, in the direction of the arrow 51) is returned to the side gap 41 through the upper gap 43, the circulation hole 318, and the lower gap 42, and the lubricating oil indicated by the arrow 55a A circulation path is formed. As a result, the pressure difference of the lubricating oil at both end faces of the sleeve member 31b is suppressed, and even if bubbles are generated in the lubricating oil, the generated bubbles are removed from the first taper gap 44 and the second taper. It can be discharged to the outside of the bearing mechanism through the taper seal of the gap 45.

  Further, in the motor 1b as well, each of the fixed shaft 22, the retaining member 23, and the sleeve member 31b is formed as one member, so that a bearing mechanism can be configured by three members, and the number of parts is reduced. In addition, the motor 1b can be easily assembled only by inserting the sleeve member 31b into the fixed shaft 22 and inserting the retaining member 23 up to the stepped portion 222.

  In addition, the same thing as the taper part 3121 and the projection part 3122 of the upper end surface 312 of the sleeve member 31 may be provided in the lower end surface 311a of the sleeve member 31b.

  Next, a method for manufacturing the sleeve member 31 of the motor 1 according to the first embodiment will be described. FIG. 11 is a diagram showing a flow of manufacturing the sleeve member 31, and FIG. A to FIG. F is a cross-sectional view illustrating a state in which the sleeve member 31 is being manufactured. When the sleeve member 31 is manufactured, a cylindrical original member 9 to be processed is prepared, and FIG. As shown to A, the base member 9 is hold | maintained by the chuck | zipper 81 which is a holding part of NC lathe (step S11). The chuck 81 is one end of the base member 9 (right side in FIG. 12A, hereinafter referred to as “processing end”) to the other end (left side in FIG. 12.A, hereinafter referred to as “holding end”). )) With respect to a tool (that is, a tool such as a drill or a bite) around a predetermined central axis J2.

  When the original member 9 is held, an end face forming process is appropriately performed, and then FIG. As shown in B, a hole 90 centered on the central axis J2 is formed on the processing end side with respect to the direction of the central axis J2 by the drill 82 in the original member 9 that rotates together with the chuck 81 (step S12).

  Once the hole 90 is formed, FIG. As shown in C, in the state where the holding end side of the original member 9 is held by the chuck 81, the processing by the cutting tool is performed. FIG. In C, the byte trajectory is indicated by reference numeral 83. In the machining by the cutting tool, first, a part of the inner peripheral surface of the hole 90 is cut into an annular shape centering on the central axis J2, so that the first thrust part is perpendicular to the central axis J2 and faces the holding end side. 91 (that is, a portion to be the tip surface of the protruding portion 3122 shown in FIG. 7) is formed as (a part of) the inner surface of the annular groove. Subsequently, by cutting the inner peripheral surface of the hole 90 in parallel to the central axis J2, the diameter of the portion on the processing end side of the first thrust portion 91 of the hole 90 is set to a predetermined diameter centered on the central axis J2. A radial dynamic pressure surface used for rotation of the sleeve member 31 is formed on the inner peripheral surface of the hole 90. A herringbone groove 316 shown in FIG. 3 is formed in the radial dynamic pressure surface in a later step. Further, by cutting the processing end side having the opening of the original member 9, the second thrust portion 92 (a portion that becomes the lower end surface 311 shown in FIG. 4) perpendicular to the central axis J <b> 2 is used to rotate the sleeve member 31. To be a thrust dynamic pressure surface). A herringbone groove 317 shown in FIG. 4 is also formed in the thrust dynamic pressure surface in a later step. (Step S13).

  Then, in the vicinity of the outer edge portion of the base member 9, a substantially cylindrical portion that protrudes toward the processing end side (that is, a portion that becomes the first annular protruding portion 313 shown in FIG. 3, hereinafter, “first annular protruding portion” 313 ”) and the outer peripheral portion of the sleeve member 31 such as the disc portion 315 shown in FIG. In addition, while the cutting tool moves along the trajectory 83, the type of cutting tool used for forming each part may be changed as appropriate. As described above, since the first thrust portion 91, the radial dynamic pressure surface, the second thrust portion 92, and other portions are molded with the original member 9 held by the same chuck 81, many portions can be formed at once. It can be processed accurately and easily.

  Next, FIG. As shown in D, with the holding end of the original member 9 held by the chuck 81, the original member 9 (the outer peripheral surface of the first annular projecting portion 313) is moved by another chuck 84 arranged on the processing end side. It is held from the second thrust part 92 side (step S14). Thereafter, in the vicinity of the bottom of the hole 90 opposite to the opening side, the base member 9 is cut at a cutting surface that is perpendicular to the central axis J2 and includes the hole 90, whereby the first thrust portion 91 and the second thrust portion are cut. The sleeve member 31 having the portion 92 is obtained (step S15).

  The sleeve member 31 separated from the original member 9 is shown in FIG. As shown in E, the surface of the sleeve member 31 opposite to the side from which the first annular projecting portion 313 projects (that is, the cutting side) is cut with a cutting tool, and the second annular projecting portion 314 shown in FIG. 7 is formed (step S16). In addition, FIG. In E, the byte trajectory is indicated by an arrow 85.

  Then, FIG. As shown in F, in a state where the sleeve member 31 is held by the chuck 84 and the rotation is stopped, two drills penetrating from the first thrust portion 91 to the second thrust portion 92 in parallel with the central axis J2 by the drill 82a. A hole 93 is formed. Thereby, the hole corresponding to the two circulation holes 318 shown in FIG. 3 can be formed efficiently (step S17). When the hole 93 is formed, the sleeve member 31 is removed from the chuck 84 and cleaned by another cleaning device or the like, and the manufacture of the sleeve member 31 is completed (step S18).

  As explained above, FIG. A to FIG. In the manufacturing method shown in F, the first thrust portion 91 and the second thrust portion 92 are formed by forming the first thrust portion 91 and the second thrust portion 92 in a state where the base member 9 is held by the chuck 81 which is the same holding portion. The accuracy of the distance between the two thrust portions 92 can be easily improved, and the accuracy of the thrust gap and the gap dimension of the thrust dynamic pressure bearing mechanism can be improved. Further, since the sleeve member 31 is a hub to which the field magnet 32 is attached (that is, the sleeve and the hub are integrated), the sleeve member 31 and the motor 1 are reduced in size (in particular, Can be made thinner). In addition, since the sleeve member 31 can be manufactured only by two times of chucking, the accuracy of the sleeve member 31 is reduced due to an increase in the number of times of chucking, and the cost increase due to the chucking operation is reduced. 31 can be manufactured with high accuracy.

  Next, a method for manufacturing the sleeve member 31a of the motor 1a according to the second embodiment will be described. The sleeve member 31a has the same steps as the manufacturing flow of the sleeve member 31 shown in FIG. 11, and the same reference numerals are given to the respective steps in the following description. FIG. A to FIG. E is a cross-sectional view showing a state in which the sleeve member 31a is being manufactured.

  When the sleeve member 31a according to the second embodiment is manufactured, the substantially cylindrical original member 9 to be processed is prepared, as in the case of manufacturing the sleeve member 31 according to the first embodiment. A hole 90 centered on the central axis J2 is formed on the machining end side in the direction of the central axis J2 with respect to the original member 9 held by the chuck 81 of the NC lathe (step S11) and rotating together with the chuck 81 (see FIG. Step S12).

  Once the hole 90 is formed, FIG. As shown in A, in a state where the holding end side of the original member 9 is held by the chuck 81, a part of the inner peripheral surface of the hole 90 is cut into an annular shape centering on the central axis J2 with a cutting tool. A first thrust portion 91a (that is, a portion that becomes the upper end surface 312a shown in FIG. 9) that is perpendicular to J2 and faces the holding end side is formed as an inner side surface (a part of) an annular deep groove. Subsequently, by cutting the inner peripheral surface of the hole 90, the diameter of the hole 90 is set to a predetermined diameter with the central axis J2 as the center, and is used for the rotation of the sleeve member 31a on the inner peripheral surface on the opening side of the hole 90. A radial dynamic pressure surface (the herringbone groove is not formed) is formed. Furthermore, the 2nd thrust part 92 perpendicular | vertical to the central axis J2 is formed by cutting the process end side which has the opening of the original member 9 (step S13). Note that FIG. In A, the trajectory of the byte is indicated by an arrow 83a.

  In the sleeve member 31a, both the first thrust portion 91a and the second thrust portion 92 are thrust dynamic pressure surfaces of the lower gap 42 and the upper gap 43 shown in FIG. A herringbone groove 317a shown in FIG. 9 is formed in the thrust portion 91a, and a herringbone groove 317 similar to the sleeve member 31 shown in FIG. 4 is formed in the second thrust portion 92.

  After the formation of the second thrust portion 92, when each portion of the outer peripheral portion of the sleeve member 31a is further formed, FIG. As shown in FIG. B, the base member 9 is held by the chuck 81 and the chuck 84 (step S14), and in the vicinity of the bottom on the side opposite to the opening side of the hole 90, FIG. By cutting the base member 9 as in the case of D, the sleeve member 31a having the first thrust portion 91a and the second thrust portion 92 is obtained (step S15). The original member 9 may be cut at the position of the groove having the first thrust portion 91a.

  The sleeve member 31a separated from the original member 9 is shown in FIG. As shown to C, the surface on the opposite side to the side from which the 1st cyclic | annular protrusion part 313 protrudes of the sleeve member 31a is cut, and the 2nd cyclic | annular protrusion part 314 is formed (step S16). Note that FIG. In C, the byte trajectory is indicated by an arrow 85a.

  Then, FIG. As shown in D, in the state where the sleeve member 31a is held by the chuck 84 and stopped rotating, two drills penetrating from the first thrust portion 91a to the second thrust portion 92 in parallel to the central axis J2 by the drill 82a. Holes 93a are formed, and these correspond to the two circulation holes 318 in FIG. 9 (step S17). When the hole 93a is formed, the sleeve member 31a is cleaned by another cleaning device or the like, and the manufacturing ends (step S18).

  In the manufacturing method of the sleeve member 31a according to the second embodiment, the first thrust portion 91a is maintained in a state where the original member 9 is held by the same holding portion, similarly to the sleeve member 31 according to the first embodiment. By forming the second thrust part 92, the accuracy of the distance between the first thrust part 91a and the second thrust part 92 can be improved. In particular, in the sleeve member 31a, since both thrust portions are used for the dynamic pressure bearing mechanism, this manufacturing method can be said to be extremely preferable. Further, since the sleeve member 31a integrally has a hub to which the field magnet 32 is attached, the sleeve member 31a and the motor 1a can be reduced in size (in particular, reduced in thickness), and the sleeve can be increased by increasing the number of times of chucking. A decrease in accuracy of the member 31a, an increase in cost due to chucking work, and the like are reduced, and the sleeve member 31a including the hub can be manufactured with high accuracy.

  The manufacturing method of the sleeve member 31a can be easily applied to the sleeve member 31b of the motor 1b according to the third embodiment of the present invention. In this case, only the first thrust portion 91a (that is, the portion serving as the thrust dynamic pressure surface of the upper gap 43) of both thrust portions is a surface on which the herringbone groove is provided in the subsequent process. In addition, the sleeve member 31b may be manufactured by the manufacturing method of the sleeve member 31 by changing the vertical relationship of the sleeve member 31b.

  As mentioned above, although embodiment of this invention has been described, this invention is not limited to the said embodiment, A various change is possible.

  For example, in the motors 1 and 1b according to the first and third embodiments, the dynamic pressure groove of the radial dynamic pressure bearing mechanism provided on the inner peripheral surface of the sleeve members 31 and 31b is the position of the bent portion of the herringbone groove. However, by increasing the number of grooves where the high dynamic pressure is required without biasing the position of the bent part, widening the groove width, or deepening the groove, the bent part (or bent part) The strength of the dynamic pressure on both sides of the position) can be made different. Thereby, there can exist an effect similar to sleeve members 31 and 31b.

  Similarly, with regard to the dynamic pressure grooves of the thrust dynamic pressure bearing mechanism, the dynamic pressure strength on both sides of the bent portion (or the position that can be regarded as the bent portion) can be increased by changing the number of grooves, the groove width, or the groove depth. It may be made different. In the case of a thrust dynamic pressure bearing mechanism, even if the outer and inner grooves of the herringbone groove are the same length, the flow of lubricating oil is faster on the outer side, so the generated pressure is higher on the outer side than on the inner side. It becomes high and generation | occurrence | production of the negative pressure on the inner peripheral side of a thrust dynamic pressure bearing mechanism can be suppressed. Further, the dynamic pressure groove of the radial dynamic pressure bearing mechanism or the thrust dynamic pressure bearing mechanism is not limited to the herringbone groove. For example, by providing the spiral dynamic pressure grooves of different directions in a double concentric shape, Alternatively, a dynamic pressure groove equivalent to the herringbone groove may be provided.

  Furthermore, in the motor 1 according to the first embodiment, the number of the agitation grooves 231 provided on the lower surface of the retaining member 23 is four. However, the number is not limited thereto, and may be one or two or more. Good.

  In the sleeve member manufacturing method, the columnar original member 9 in which the hole 90 is not formed is held by the chuck 81, and the hole 90 is formed by a drill, whereby the original member 9 in which the hole 90 is formed is chucked. 81. The original member 9 in which the hole 90 is formed in advance or the pipe-shaped original member 9 in which the through hole is formed in advance is held by the chuck 81, so that the central shaft is prepared. An original member in which a hole having an opening on at least one side with respect to J2 may be prepared while being held by the chuck 81.

  The recording disk drive device 60 having the motor according to the above embodiment is not limited to a hard disk device, and may be a disk drive device such as a removable disk device.

It is a figure which shows the internal structure of a recording disk drive device. It is a longitudinal cross-sectional view which shows the structure of a motor. It is a longitudinal cross-sectional view which shows a sleeve member. It is a bottom view which shows the lower end surface of a sleeve member. It is a longitudinal cross-sectional view which expands and shows a part of motor. It is a figure which shows the relative level of the pressure which arises in lubricating oil. It is a bottom view which shows a retaining member. It is a longitudinal cross-sectional view which expands and shows an upper gap | interval. It is a longitudinal cross-sectional view which expands and shows a part of motor. It is a top view which shows the upper end surface of a sleeve member. It is a longitudinal cross-sectional view which expands and shows a part of motor. It is a figure which shows the flow of manufacture of a sleeve member. It is sectional drawing which shows the mode in the middle of manufacture of a sleeve member. It is sectional drawing which shows the mode in the middle of manufacture of a sleeve member. It is sectional drawing which shows the mode in the middle of manufacture of a sleeve member. It is sectional drawing which shows the mode in the middle of manufacture of a sleeve member. It is sectional drawing which shows the mode in the middle of manufacture of a sleeve member. It is sectional drawing which shows the mode in the middle of manufacture of a sleeve member. It is sectional drawing which shows the mode in the middle of manufacture of a sleeve member. It is sectional drawing which shows the mode in the middle of manufacture of a sleeve member. It is sectional drawing which shows the mode in the middle of manufacture of a sleeve member. It is sectional drawing which shows the mode in the middle of manufacture of a sleeve member.

Explanation of symbols

1, 1a, 1b Motor 9 Original member 21 Base plate 22 Fixed shaft 23 Stopping member 24 Armature 31, 31a, 31b Sleeve member 32 Field magnet 41 Side gap 42 Lower gap 43 Upper gap 44 First taper gap 45 Second Tapered gap 60 Recording disk drive device 62 Recording disk 81, 84 Chuck 90 Hole 91, 91a First thrust part 92 Second thrust part 221 Flange part 222 Step part 231 Stirring groove 311, 311a Lower end face 312, 312a Upper end face 313 First Annular protrusion 314 Second annular protrusion 316, 316a, 316b, 317, 317a Herringbone groove 318 Circulation hole 631 Head 632 Arm 633 Head part moving mechanism 3121 Taper part 3122 Projection part J1, J2 Central shaft S11-S18 Step

Claims (20)

A bearing mechanism using fluid dynamic pressure used in an electric motor,
A fixed shaft having one end fixed at a predetermined mounting position, a flange portion extending outward from the central axis on the one end side, and a stepped portion having a reduced diameter on the other end side;
A sleeve member inserted into the fixed shaft and having one end surface facing the flange portion;
An annular retaining member attached to the stepped portion of the fixed shaft and facing the other end surface of the sleeve member;
A biasing mechanism that biases the sleeve member toward the flange portion in a non-contact manner by a magnetic action;
With
A radial dynamic pressure bearing mechanism is formed between the fixed shaft and the inner peripheral surface of the sleeve member, and a thrust dynamic pressure bearing mechanism is formed between the one end surface of the sleeve member and the flange portion,
The sleeve member is
A first annular protrusion that protrudes from the one end surface and covers the outer peripheral surface of the flange;
A second annular protrusion protruding from the other end face and covering the outer peripheral surface of the retaining member;
With
Lubricating oil is continuously filled in the filling gap between the fixed shaft, the retaining member and the sleeve member,
A first taper gap is formed between the flange portion and the first annular projecting portion so as to gradually increase as the distance from the one end surface of the sleeve member increases, and between the retaining member and the second annular projecting portion. A second taper gap that gradually increases as the distance from the other end surface of the sleeve member increases is formed, and a taper seal is formed in the first taper gap and the second taper gap by the lubricating oil continuous from the filling gap. A bearing mechanism characterized by that. A bearing mechanism using fluid dynamic pressure used in an electric motor,
A fixed shaft having one end fixed at a predetermined mounting position, a flange portion extending outward from the central axis on the one end side, and a stepped portion having a reduced diameter on the other end side;
A sleeve member inserted into the fixed shaft and having one end surface facing the flange portion;
An annular retaining member attached to the stepped portion of the fixed shaft and facing the other end surface of the sleeve member;
With
A radial dynamic pressure bearing mechanism is formed between the fixed shaft and the inner peripheral surface of the sleeve member, and between the one end surface of the sleeve member and the flange portion and the other end surface of the sleeve member and the A thrust dynamic pressure bearing mechanism is formed on at least one of the retaining members,
The sleeve member is
A first annular protrusion that protrudes from the one end surface and covers the outer peripheral surface of the flange;
A second annular protrusion protruding from the other end face and covering the outer peripheral surface of the retaining member;
With
Lubricating oil is continuously filled in the filling gap between the fixed shaft, the retaining member and the sleeve member,
A first taper gap is formed between the flange portion and the first annular projecting portion so as to gradually increase as the distance from the one end surface of the sleeve member increases, and between the retaining member and the second annular projecting portion. A second taper gap that gradually expands away from the other end face of the sleeve member is formed, and a taper seal is formed by the lubricating oil continuous from the filling gap in the first taper gap and the second taper gap;
The sleeve member is a hub to which a field magnet is attached,
Each of the fixed shaft, the sleeve member, and the retaining member is formed as one member. The bearing mechanism according to claim 2,
A thrust dynamic pressure bearing mechanism is formed only between the one end surface of the sleeve member and the flange portion. The bearing mechanism according to claim 1 or 3,
The dynamic pressure groove of the radial dynamic pressure bearing mechanism is a herringbone groove, and the pressure generated at the other end face side portion of the herringbone groove is higher than the pressure generated at the one end face side portion. A bearing mechanism characterized by that. The bearing mechanism according to claim 1, 3 or 4,
The dynamic pressure groove of the thrust dynamic pressure bearing mechanism is a herringbone groove, and the pressure generated at the site on the first annular projecting portion side of the herringbone groove is higher than the pressure generated at the site on the fixed shaft side. Bearing mechanism characterized by being high. The bearing mechanism according to any one of claims 1 and 3 to 5,
The bearing mechanism, wherein the sleeve member includes a circulation hole that guides the lubricating oil from an outer peripheral side of the flange portion to an outer peripheral side of the retaining member. The bearing mechanism according to claim 6,
The bearing mechanism, wherein the retaining member includes an agitation groove on a surface opposite to the other end surface of the sleeve member, while facing the outer side in the radial direction and in a direction opposite to the rotation direction of the sleeve member. A bearing mechanism according to any one of claims 1 and 3 to 7,
A bearing mechanism, wherein the other end surface of the sleeve member is provided with a taper portion in which a gap between the sleeve member and the retaining member gradually increases toward the outside in the radial direction. The bearing mechanism according to claim 8, wherein
The bearing mechanism, wherein the sleeve member includes a protrusion that protrudes closer to the retaining member than the taper portion around the fixed shaft on the other end surface. The bearing mechanism according to claim 2,
A bearing mechanism, wherein a thrust dynamic pressure bearing mechanism is formed only between the other end surface of the sleeve member and the retaining member. The bearing mechanism according to claim 10,
The dynamic pressure groove of the radial dynamic pressure bearing mechanism is a herringbone groove, and the pressure generated at the one end surface side portion of the herringbone groove is higher than the pressure generated at the other end surface side portion. A bearing mechanism characterized by that. The bearing mechanism according to claim 10 or 11,
The dynamic pressure groove of the thrust dynamic pressure bearing mechanism is a herringbone groove, and the pressure generated at the site on the second annular protrusion side of the herringbone groove is higher than the pressure generated at the site on the fixed shaft side. Bearing mechanism characterized by being high. The bearing mechanism according to any one of claims 10 to 12,
The bearing mechanism, wherein the sleeve member includes a circulation hole that guides the lubricating oil from the outer peripheral side of the retaining member to the outer peripheral side of the flange portion. A bearing mechanism according to any one of claims 1 and 3 to 13,
Of the radial dynamic pressure bearing mechanism, the radial dynamic pressure bearing mechanism, of the width of the thrust dynamic pressure bearing mechanism, the width of the thrust gap of the sleeve member on the opposite side of the thrust dynamic pressure bearing mechanism A bearing mechanism characterized in that the width of the gap is the narrowest and the width of the thrust gap is the widest. An electric motor,
A bearing mechanism according to any one of claims 1 to 14,
A base portion to which the one end of the fixed shaft is fixed;
Armature,
A field magnet that is attached to the sleeve member and generates a torque centered on a predetermined central axis with the armature;
A motor comprising: A recording disk drive device comprising:
A recording disk for recording information;
The motor according to claim 15, which rotates the recording disk;
A head unit for reading and / or writing information on the recording disk;
A head part moving mechanism for moving the head part relative to the recording disk and the motor;
A recording disk drive device comprising: A method of manufacturing a sleeve member into which a fixed shaft of a motor having a bearing mechanism using fluid dynamic pressure is inserted,
a) A holding portion that rotates the other end of the original member to be processed having a hole having an opening on one end side relative to the tool about a predetermined central axis from the one end toward the other end. A step of preparing in a state held in
b) By cutting a part of the inner peripheral surface of the hole into an annular shape centering on the central axis while the original member is held by the holding portion, the other end is perpendicular to the central axis and the other end Forming a first thrust portion facing the side as an inner surface of the annular groove;
c) cutting the inner peripheral surface of the hole in a state where the original member is held by the holding portion, thereby setting the diameter of the hole to a predetermined diameter centered on the central axis;
d) forming a second thrust portion perpendicular to the central axis by cutting the one end side in a state where the original member is held by the holding portion;
e) obtaining a sleeve member having the first thrust portion and the second thrust portion by cutting the original member;
With
A method for manufacturing a sleeve member, wherein at least one of the first thrust portion and the second thrust portion is a thrust dynamic pressure surface used for rotation of the sleeve member. A method for manufacturing a sleeve member according to claim 17,
In the step c), a radial dynamic pressure surface used for rotation of the sleeve member is formed on the inner peripheral surface of the hole. A method of manufacturing a sleeve member according to claim 17 or 18,
f) The method for manufacturing a sleeve member, further comprising a step of holding the original member from the second thrust part side after the step d) and before the step e). A method of manufacturing a sleeve member according to any one of claims 17 to 19,
A method of manufacturing a sleeve member, wherein the sleeve member is a hub to which a field magnet is attached.

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