JP2008190660A - Bearing mechanism, motor, and recording disk drive device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the male screw part of a thrust plate from being loosened off the female screw part of a shaft. <P>SOLUTION: This bearing mechanism 4 of a motor 10 comprises the shaft 311 and the thrust plate 5. The thrust plate 5 is fitted to the end of the shaft 311 since the male screw part 51 of the thrust plate 5 is screwed to the female screw part 3112 formed at the lower part of the shaft 311 without using an adhesive agent. In the motor 10, the rotating direction of a rotor part 3 is counterclockwise in plan view. A left-handed screw is adopted for the male screw part 51. When an impact or vibration is applied to a motor 10 during the starting, stopping, and rotating, a force is applied to the thrust plate 5 in the direction that the male screw part 51 is screwed into the female screw part 3112. Consequently, the male screw part 51 is prevented from being loosened off the female screw part 3112. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a bearing mechanism that uses fluid dynamic pressure, a motor including the bearing mechanism, and a recording disk drive device.

  2. Description of the Related Art Conventionally, a recording disk drive device such as a hard disk device has a spindle motor that rotationally drives a recording disk, and a bearing mechanism that uses fluid dynamic pressure has been adopted as one of the motor bearing mechanisms. Some of such bearing mechanisms have a disc-shaped thrust plate attached to the tip of the rotating shaft.

For example, in the motor of Patent Document 1, a thrust plate is fixed to a shaft so as to be sandwiched between a screw head and a rotating shaft by a fixing screw. Thus, the rotor member rotates counterclockwise, and the screw member that fixes the thrust plate is a right-hand screw.
JP 2002-310147 A

  However, as shown in Patent Document 1, when the fixing screw that is a male screw is a right-hand screw and the rotation direction viewed from the rotor part side of the motor is counterclockwise, when the motor is started or stopped, or If an impact or vibration is applied during rotation, the screwed screw may be loosened.

  The present invention has been made in view of the above-described problems, and has as its main purpose to prevent the male screw portion for fixing the thrust plate from loosening from the female screw portion of the shaft.

  The invention according to claim 1 is a bearing mechanism using fluid dynamic pressure for a motor, and a radial dynamic pressure bearing portion is interposed between the shaft and the shaft through which the shaft is inserted and lubricating oil. A sleeve to be formed, a thrust plate attached to one end of the shaft and facing the end surface of the sleeve, a bottomed cylinder that covers the outer peripheral surface of the sleeve and the thrust plate, and holds lubricating oil around the thrust plate The thrust plate is screwed into a female screw portion formed along the central axis at the one end of the shaft, and the shaft rotates relative to the sleeve. And a male screw part whose direction of rotation is screwed into the female screw part, and extends outward from the male screw part around the central axis. Facing the end face of the sleeve, and a disk portion forming the thrust dynamic pressure bearing portion between the end surface via a lubricant.

  The invention according to claim 2 is the bearing mechanism according to claim 1, wherein the hole in which the female screw portion is formed does not penetrate the shaft.

  The invention according to claim 3 is the bearing mechanism according to claim 2, wherein the thrust plate is fixed to the shaft only by screwing the male screw part into the female screw part.

  Invention of Claim 4 is a bearing mechanism of Claim 3, Comprising: The area | region between the said external thread part and the said female thread part between the said one end of the said shaft and the said disk part. And a channel that communicates with the outside of the shaft, and from the gap between the end face of the sleeve and the disc portion, the channel between the channel and the male screw portion and the female screw portion. Through the region, the lubricating oil is continuously filled up to the inside of the hole where the female screw portion is formed.

  The invention according to claim 5 is the bearing mechanism according to claim 4, wherein the flow path and the inside of the hole are communicated between the male screw portion and the female screw portion. A road is provided.

  Invention of Claim 6 is a bearing mechanism of Claim 4 or 5, Comprising: The said thrust plate has a through-hole which penetrates the said external thread part and the said disk part along the said central axis. .

  A seventh aspect of the present invention is the bearing mechanism according to the third aspect, wherein the thrust plate has a through hole penetrating the male screw portion and the disc portion along the central axis.

  The invention according to claim 8 is the bearing mechanism according to any one of claims 4 to 7, wherein the thrust plate is formed of a material having a lower thermal expansion coefficient than the shaft.

  Invention of Claim 9 is a bearing mechanism in any one of Claim 2 thru | or 8, Comprising: The other internal thread part is formed in the other end of the said shaft along the said central axis, The spiral of the thread is opposite in the female screw portion at the one end and the other female screw portion at the other end.

  The invention according to claim 10 is an electric motor, wherein the bearing mechanism according to any one of claims 1 to 9 and a rotor portion attached to the other end of the shaft opposite to the one end. And a stator portion to which the sleeve housing is fixed.

  The invention according to claim 11 is a recording disk drive device, wherein the motor according to claim 10 rotates the recording disk, an access unit for reading and / or writing information on the recording disk, and the motor And a housing for accommodating the access portion.

  According to the present invention, the male screw portion of the thrust plate is prevented from loosening from the female screw portion of the shaft. In the invention of claim 2, oil is prevented from leaking from the shaft.

  In the invention of claim 3, the assembly of the bearing mechanism can be simplified, and in the invention of claim 4, minute foreign matter generated in the bearing mechanism is accumulated inside the shaft or between the shaft and the thrust plate. Thus, it is possible to suppress a decrease in bearing performance. In the invention of claim 5, the lubricating oil can be easily filled in the shaft.

  According to the sixth aspect of the present invention, the pressure of the lubricating oil can be suppressed from decreasing between the lower surface of the thrust plate and the bottom of the sleeve housing during the rotation of the shaft. By accumulating minute foreign matters generated in the above in the shaft and in the through hole, it is possible to suppress a decrease in bearing performance. In the invention of claim 8, the fluctuation of the height of the oil interface can be reduced, and oil leakage can be prevented.

  FIG. 1 is a cross-sectional view of a recording disk drive apparatus 1 including an electric spindle motor (hereinafter referred to as “motor”) according to a first embodiment of the present invention. The recording disk drive 1 is a so-called hard disk drive, and holds two disk-shaped recording disks 11 for recording information, an access unit 12 for writing and reading information to and from the recording disk 11, and a recording disk 11. An electric motor 10 that rotates, and a housing 13 that houses the recording disk 11, the access unit 12, and the motor 10 in the internal space are provided.

  The housing 13 has an opening in the upper portion, a first housing member 131 having a lidless box shape to which the motor 10 and the access unit 12 are attached to an inner bottom surface, and a plate-shaped second housing that covers the opening of the first housing member 131. A member 132 is provided. In the recording disk drive 1, the second housing member 132 is joined to the first housing member 131 to form the housing 13, and the internal space is a clean space with extremely little dust and dirt.

  Two recording disks 11 are placed on the motor 10 with a spacer 15 in between, and are fixed to the motor 10 by screws 16 and a clamper 14. The access unit 12 includes a head 121 that magnetically reads and writes information in the vicinity of the recording disk 11, an arm 122 that supports the head 121, and moves the arm 122 to move the head 121 to the recording disk 11 and the motor. 10 has a head moving mechanism 123 that moves relative to 10. With these configurations, the head 121 accesses a required position of the recording disk 11 in the state of being close to the rotating recording disk 11, and writes and reads information.

  FIG. 2 is a longitudinal sectional view of the motor 10, and two recording disks 11 are indicated by a two-dot chain line. The motor 10 is an outer rotor type motor, and includes a stator unit 2 that is a fixed assembly, a rotor unit 3 that is a rotating assembly, and a bearing mechanism 4 that uses fluid dynamic pressure by lubricating oil that is a working fluid. The rotor part 3 is rotatably supported with respect to the stator part 2 around the central axis J1 of the motor 10 via the bearing mechanism 4, and rotates counterclockwise, which is one direction when the motor 10 is viewed in plan. . The “rotation direction of the motor 10” in the following description refers to the rotation direction of the rotor portion 3 when the motor 10 is viewed in a plan view unless otherwise specified, but in a part of the description, the motor 10 is viewed from the bottom side. The direction of rotation is also mentioned. For convenience, the rotor unit 3 side will be described as the upper side and the stator unit 2 side will be the lower side along the central axis J1, but the central axis J1 does not necessarily coincide with the direction of gravity.

  The rotor portion 3 includes a rotor hub 31 that is formed of stainless steel or the like and serves as a main body of the rotor portion 3. The rotor hub 31 has a shaft 311 that protrudes downward from the center axis J1 (that is, the stator portion 2 side), A substantially disc-shaped disc portion 312 extending perpendicularly from the upper end portion of the shaft 311 to the central axis J1 and a substantially cylindrical tubular portion 313 projecting downward from the outer periphery of the disc portion 312 are provided. A field magnet 32 is attached to the inner surface of the cylindrical portion 313.

  In the shaft 311, female screw parts 3111 and 3112 are formed along the central axis J <b> 1 at the upper end and the lower end, respectively, and holes in which the female screw parts 3111 and 3112 are formed are provided without penetrating the shaft 311. The upper female screw portion 3111 is screwed with a screw 16 for fixing the clamper 14 on the disc portion 312. When the motor 10 is viewed in plan, the screw 16 is in a direction opposite to the rotation direction of the motor 10 (clockwise). ) And is screwed into the female screw portion 3111 (that is, the screw 16 and the female screw portion 3111 are right-handed screws). A thrust plate 5 described later is attached to the lower female screw portion 3112.

  The stator unit 2 includes a base bracket 21 having a substantially cylindrical holder 211 at the center, and an armature 22 attached around the holder 211. A cylindrical sleeve housing 41 with a bottom which will be described later is inserted into the holder 211 and fixed. The armature 22 faces the field magnet 32 in the radial direction, and generates a rotational force (torque) centered on the shaft 311 (that is, the central axis J1) with the field magnet 32.

  The bearing mechanism 4 includes a sleeve 42 into which the shaft 311 is inserted, a thrust plate 5, and a sleeve housing 41 that covers the outer peripheral surface of the sleeve 42 and the thrust plate 5 (the outer periphery and the lower surface thereof). The sleeve 42 is a porous member made of sintered metal, and the sleeve housing 41 plays a role of holding the lubricating oil impregnated in the sleeve 42 around the thrust plate 5. Since the shaft 311 rotates relative to the sleeve 42 together with the rotation of the rotor unit 3, the “rotation direction of the motor 10” described above is also a direction in which the shaft 311 rotates relative to the sleeve 42. it can. The thrust plate 5 includes a male screw part 51 that is screwed into the female screw part 3112 of the shaft 311 and a disk part 52 that extends outward from the male screw part 51 around the central axis J1, and is more thermally expanded than the shaft 311. It is formed of a material having a low rate (for example, iron material).

  The disk part 52 has a male screw part 51 screwed into the lower end of the shaft 311 so that the upper surface thereof faces the lower end surface of the sleeve 42 and forms a gap for generating fluid dynamic pressure. The male screw portion 51 is a left screw, and when the motor 10 is viewed from below, the male screw portion 51 is screwed into the female screw portion 3111 by rotating counterclockwise. Since the motor 10 at the time of rotation rotates clockwise as viewed from the lower side, the rotation direction of the motor 10 is opposite to the rotation direction of the motor 10 when viewed from the lower side. It will be the direction to be screwed in. As described above, since the upper female screw portion 3111 is a right-hand screw, the spiral of the screw thread is opposite in the female screw portion 3112 and the female screw portion 3111. That is, the directions of rotation with respect to the traveling direction of the spiral are opposite to each other. Further, the space between the male screw portion 51 and the female screw portion 3112 is not sealed with an adhesive or the like (that is, the lubricating oil can enter the inside), and the female screw portion 3112 is formed as will be described later. The inside of the hole to be filled is filled with lubricating oil.

  FIG. 3 is an enlarged sectional view showing a part of the motor 10 (the right half in FIG. 2). In the motor 10, between the lower surface of the disk portion 312 of the rotor hub 31 and the upper end surface 422 of the sleeve 42, between the inner surface 423 of the sleeve 42 and the outer surface of the shaft 311, the lower end surface 424 of the sleeve 42 and the thrust plate 5. Between the outer surface 413 of the upper portion of the sleeve housing 41 and the inner surface of the annular protrusion 314 protruding downward from the disk portion 312 outside the sleeve housing 41. Gaps are provided. Hereinafter, these gaps are referred to as “upper gap 61”, “side gap 62”, “lower gap 63”, and “outer gap 64”, respectively.

  In addition, the outer surface 421 of the sleeve 42 is provided with a plurality of grooves 651 parallel to the central axis J1, and the inner surface of the sleeve housing 41 surrounds the outer surface 421 of the sleeve 42. A plurality of flow paths 65 in the direction of the central axis J1 are formed between the sleeve housing 41 and the upper gap 61 and the lower gap 63 communicate with each other by the plurality of flow paths 65 (in practice, the lower end of the sleeve 42 and the sleeve housing are connected). The flow path (not shown) is also provided in the abutting portion between the bottom 41 and the bottom 41). In the motor 10, the plurality of flow paths 65 and the gaps 61 to 64 are continuously filled with lubricating oil, so that a bearing mechanism 4 having a so-called full-fill structure is configured. The width of the outer gap 64 (that is, the distance between the outer surface 413 of the sleeve housing 41 and the inner surface of the annular protrusion 314 of the rotor hub 31) gradually increases from the upper end of the sleeve housing 41 downward. As a result, a taper seal in which the interface of the lubricating oil has a meniscus shape is formed in the outer gap 64 to prevent the lubricating oil from flowing out, and the outer gap 64 serves as an oil buffer.

  FIG. 4 is a plan view of the sleeve 42. A spiral thrust dynamic pressure groove 4221 (a parallel oblique line is attached to the bottom surface of the groove 4221) is formed on the upper end surface 422 of the sleeve 42, and the upper gap 61 is rotated by the groove 4221 when the rotor unit 3 rotates. (See FIG. 3) A thrust dynamic pressure bearing portion that generates pressure toward the central axis J1 with respect to the lubricating oil is configured. FIG. 5 is a view showing a cross section of the sleeve 42 in a plane including the central axis J1. The inner surface 423 of the sleeve 42 is provided with a plurality of herringbone-shaped radial dynamic pressure grooves 4231 and 4232 (in parallel to the bottom surfaces of the grooves 4231 and 4232) at two upper and lower portions, respectively. A radial dynamic pressure bearing portion that generates fluid dynamic pressure in the side gap 62 between the shaft 411 and the shaft 311 (see FIG. 3) by the grooves 4231 and 4232 at the time of rotation is formed via the lubricating oil. During this time, the lubricating oil is pushed in and kept at a positive pressure. Since the shaft 311 also functions as a part of the bearing mechanism 4, a part that is attached to the upper end of the shaft 311 and rotates with the shaft 311 regarded as a part of the bearing mechanism 4 may be regarded as the rotor unit 3.

  FIG. 6 is a bottom view of the sleeve 42. The lower end surface 424 of the sleeve 42 is provided with a plurality of spiral-shaped thrust dynamic pressure grooves 4241 (the bottom surface of the groove 4241 is indicated by a parallel oblique line). The groove 4241 and the disc portion 52 of the thrust plate 5 are provided. (See FIG. 3), a thrust dynamic pressure bearing portion that generates pressure toward the central axis J1 in the lower gap 63 between the disc portion 52 and the sleeve 42 when the rotor portion 3 rotates (however, The lubricating oil receives a force from the radial dynamic pressure bearing portion and flows away from the central axis J1.) Is formed through the lubricating oil. As shown in FIGS. 4, 5, and 6, the plurality of grooves 651 described above extending in the vertical direction are provided at substantially equal intervals on the outer periphery of the sleeve 42 (three in the present embodiment). .

  FIG. 7 is a bottom view of the shaft 311. Four grooves 3114 having a V-shaped cross section are formed at equal intervals in the circumferential direction on the lower end surface 3113 of the shaft 311, and the grooves 3114 extend radially outward from the female screw portion 3112 to the outer periphery of the lower end surface 3113. ing. FIG. 8 is a plan view of the thrust plate 5. Four grooves 511 extending in parallel with the central axis J1 are provided in the outer peripheral portion of the male screw portion 51 at equal intervals in the circumferential direction. The grooves 511 extend from the upper surface of the disc portion 52 to the upper end of the male screw portion 51. The depth of the groove 511 is made deeper than the thread of the male screw portion 51.

  FIG. 9 is a longitudinal sectional view showing the lower part of the bearing mechanism 4 at the position of the arrow A shown in FIGS. When the thrust plate 5 is attached to the shaft 311 at the time of assembling the bearing mechanism 4 (that is, when the male screw portion 51 is screwed to the female screw portion 3112), the disc portion 52 of the thrust plate 5 becomes the groove shown in FIG. It abuts on the lower end surface 3113 of the shaft 311 in a region other than 3114. Thereby, a flow path 71 extending in the radial direction by the groove 3114 is provided between the disc portion 52 and the lower end of the shaft 311. At the same time, a channel 72 parallel to the central axis J1 is provided by the groove 511 of the male screw portion 51 between the male screw portion 51 of the thrust plate 5 and the female screw portion 3112 provided on the shaft 311.

  The channel 71 communicates the channel 72 and the outside of the shaft 311, and the channel 72 communicates the channel 71 and the inside of the hole of the shaft 311. As described above, the space between the male screw portion 51 and the female screw portion 3112 is not sealed with an adhesive or the like, and the lower gap 63 (that is, between the lower end surface 424 of the sleeve 42 and the disc portion 52). ) Through the flow paths 71 and 72 to the space 73 that is the inside of the hole in which the female screw portion 3112 is formed.

  Although the structure of the motor 10 has been described above, the motor 10 rotates counterclockwise when viewed in plan, and a left screw is employed for the male thread portion 51 of the thrust plate 5. When stopping and when an impact or vibration is applied during rotation, a force acts on the thrust plate 5 in the direction in which the screw is tightened, and the male screw portion 51 is prevented from loosening from the shaft 311. Furthermore, an adhesive for preventing loosening that seals between the male screw portion 51 and the female screw portion 3112 can be omitted, and the assembly of the bearing mechanism 4 can be simplified. Since the hole in which the two female screw portions 3111 and 3112 are formed does not penetrate the shaft 311, the lubricating oil does not leak from the inside of the shaft 311 to the outside of the bearing mechanism 4, and the rigidity of the shaft 311 is also reduced by that of the through hole. Higher than the case.

  Furthermore, the thrust plate 5 is fixed to the shaft 311 only by screwing the male screw part 51 into the female screw part 3112 (that is, an adhesive is used between the male screw part 51 and the female screw part 3112). And the thrust plate 5 is fixed to the lower end of the shaft 311), the lubricating oil can easily enter the space 73 inside the shaft 311 via the flow paths 71 and 72, and easily into the entire space 73. Can be filled with lubricating oil. This prevents bubbles from remaining in the space 73, suppresses vibrations such as NRRO (non-repetitive vibration), improves the reliability of the bearing mechanism 4 (and the motor 10), and extends the life. be able to.

  In the case of using an adhesive, if the adhesive deteriorates due to temperature change or humidity change, bubbles in the adhesive may enter the bearing mechanism. However, in the bearing mechanism 4 that does not use the adhesive, Such a problem does not occur.

  In addition, since the thrust toward the central axis J1 is generated in the lubricating oil in the thrust hydrodynamic bearing portion of the lower gap 63 due to the rotation of the rotor portion 3, the pressure of the lubricating oil is greater than that in the space 73 side when the motor 10 is started. The 71 side is in a higher state. As a result, the lubricating oil flows from the outside of the shaft 311 into the flow paths 71 and 72 and the space 73, and minute foreign matters in the lubricating oil accumulate and accumulate in the flow paths 71 and 72 and the space 73. . When the motor 10 is stopped, the pressure on the space 73 side decreases, but the foreign matter that has once entered the flow paths 71 and 72 and the space 73 is not easily returned to the outside of the shaft 311 (the shaft 311 and the thrust plate). 5 constitutes a so-called dust trap). As a result, foreign matter generated in the bearing mechanism 4 can be accumulated inside the shaft 311 or between the shaft 311 and the thrust plate 5, and deterioration of bearing performance can be suppressed.

  On the other hand, in the bearing mechanism 4, as described above, the thrust plate 5 is formed of a material having a lower coefficient of thermal expansion than that of the shaft 311. Therefore, the space 73 in the shaft 311 expands when the temperature in the bearing mechanism 4 becomes high. Shrinks at low temperatures. Similarly, the volume of the lubricating oil increases when the temperature becomes high, and the volume decreases when the temperature becomes low. However, a large amount of the lubricating oil is taken into the space 73 at a high temperature, so that the lubricating oil interface of the outer gap 64 shown in FIG. Variations in height with temperature are reduced. This prevents the lubricating oil from leaking out of the taper seal and suppresses the scattering of the lubricating oil due to impact.

  As shown in FIG. 6, the thrust dynamic pressure groove 4241 is bent counterclockwise from the center toward the outside, so that the male screw portion 51 rotates counterclockwise to the female screw portion 3112 in the assembly of the bearing mechanism 4. When screwed, even if the thrust dynamic pressure groove 4241 and the disc portion 52 of the thrust plate 5 come into contact with each other, they are rubbed in the same direction as the pattern of the groove 4241. The generated foreign matter is also guided to the outside along the groove and can be easily removed.

  FIG. 10 is a plan view of a thrust plate 5a according to another example of the bearing mechanism 4 according to the first embodiment. In the thrust plate 5a, in place of the plurality of grooves 3114 of the shaft 311 shown in FIG. 7, a plurality of grooves 521 having a V-shaped cross section extending in the radial direction are provided on the upper surface of the disc portion 52. Other configurations of the bearing mechanism 4 are the same as those in the first embodiment. The ends on the central axis J1 side of the plurality of grooves 521 are connected to the plurality of grooves 511 provided on the outer peripheral portion of the male screw portion 51, and the grooves 521 extend to the outer periphery of the disc portion 52.

  FIG. 11 is a longitudinal sectional view showing the lower part of the bearing mechanism 4 at the position of the arrow B shown in FIG. In the case of the bearing mechanism 4 in FIG. 11, the circular plate portion 52 of the thrust plate 5 a comes into contact with the lower end surface 3113 of the shaft 311, whereby a radial flow path 71 a is formed in the groove 521. Then, the lubricating oil is continuously filled from the lower gap 63 through the flow path 71a and the axial flow path 72 to the space 73 inside the hole in which the female screw portion 3112 is formed.

  Also in the bearing mechanism 4 shown in FIG. 11, as in the case of the bearing mechanism 4 shown in FIG. 9, the left screw is employed in the male screw portion 51 that is screwed into the female screw portion 3112 of the shaft 311, and the motor 10 is started. The male screw portion 51 of the thrust plate 5 is prevented from loosening from the shaft 311 when vibration is applied at the time of stopping or at the time of rotation or when the motor 10 is rotating. Accordingly, the thrust plate 5 can be attached to the shaft 311 only by screwing the male screw portion 51 into the female screw portion 3112 without the adhesive that seals between the male screw portion 51 and the female screw portion 3112. The assembly of the bearing mechanism 4 can be simplified. Further, when the motor 10 is started, foreign matters flow into the flow paths 71 and 72 and the space 73, so that it is possible to suppress a decrease in bearing performance.

  FIG. 12 is a view showing a cross section of the thrust plate 5b of the bearing mechanism according to the second embodiment. In the thrust plate 5b, the groove 511 of the male screw portion 51 is omitted from the thrust plate 5 shown in FIG. 8, and a through hole 53 is provided through the male screw portion 51 and the disc portion 52 along the central axis J1. It has become. Such a thrust plate 5b can be manufactured at low cost by processing a pipe material. FIG. 13 is an enlarged longitudinal sectional view showing a lower portion of the bearing mechanism 4a according to the second embodiment, and corresponds to FIG. In the bearing mechanism 4a, the flow paths 71 and 72 of the bearing mechanism 4 according to the first embodiment are not provided, and the space 73 inside the shaft 311 is formed between the lower surface of the thrust plate 5b and the sleeve by the through hole 53 of the thrust plate 5b. It communicates with a gap 66 between the bottom of the housing 41. The gap 66, the through hole 53, and the space 73 communicating with the lower gap 63 are filled with the lubricating oil. Other configurations are the same as those of the bearing mechanism 4 according to the first embodiment.

  When the motor 10 is stopped, a minute foreign matter generated in the bearing mechanism 4a flows into the through-hole 53 or the space 73 due to a pressure difference with the gap 66 when the motor 10 is stopped. Accumulate in 53. As a result, similar to the first embodiment, a decrease in bearing performance is suppressed. Also in the second embodiment, since a left screw is employed for the male screw portion 51, the male screw portion 51 is prevented from loosening from the female screw portion 3112.

  FIG. 14 is an enlarged view showing a lower part of the bearing mechanism 4b according to the third embodiment. Similarly to the thrust plate 5b shown in FIG. 13, the thrust plate 5c of the bearing mechanism 4b has a through hole 53 penetrating the male screw portion 51 and the disc portion 52 along the central axis J1, and the thrust plate 5 of FIG. Similarly, the male screw portion 51 also has four grooves 511 extending in the axial direction. The shaft 311 is the same as that shown in FIG. 7 and has four grooves 3114 on the lower end surface 3113. Other configurations are the same as those of the first embodiment, and the same reference numerals are given to the same configurations.

  In the bearing mechanism 4 b, when the male screw portion 51 is screwed into the female screw portion 3112 of the shaft 311, a channel 72 is formed between the male screw portion 51 and the female screw portion 3112 by the groove 511, and the groove 3114. Thus, a flow path 71 is formed between the lower end of the shaft 311 and the disc portion 52. The channel 71 communicates the channel 72 and the outside of the shaft 311, and the channel 72 communicates the channel 71 and the space 73 inside the hole of the shaft 311. The space 73 communicates with the gap 66 below the thrust plate 5 c through the through hole 53 and further communicates with the lower gap 63. The flow paths 71 and 72, the space 73 and the through hole 53 are continuously filled with lubricating oil. When the rotor unit 3 rotates, the filled lubricating oil passes through the flow paths 71 and 72 and the space 73. Flows into the gap 66 through the through hole 53.

  The gap 66 (particularly in the vicinity of the center) is likely to be negative pressure due to centrifugal force, but by supplying lubricating oil to the gap 66 through the through hole 53, the pressure drop is suppressed and the generation of bubbles is prevented. The Further, during the rotation of the motor 10, the foreign matter generated in the bearing mechanism 4b flows into the space 73 through the flow paths 71 and 72 as in the bearing mechanism 4 shown in FIG. 72, the space 73 or the through hole 53. As a result, a decrease in bearing performance is suppressed. Also, in the case of the bearing mechanism 4b, a left screw is employed as the male screw portion 51 of the thrust plate 5c, and the male screw portion 51 is prevented from being loosened from the female screw portion 3112.

  FIG. 15 is a cross-sectional view showing a part of a motor 10a according to the fourth embodiment. In the bearing mechanism 4c of the motor 10a, the shaft 311a has a through hole, and female screw portions 3111 and 3112 are formed along the central axis J1 at the upper and lower ends of the shaft 311a. The screw 16 for attaching the screw is screwed, and the male screw portion 51 of the thrust plate 5d is screwed to the female screw portion 3112. In the shaft 311a, the groove 3114 provided on the lower end surface 3113 shown in FIG. 7 is omitted, and the thrust plate 5d is obtained by omitting the groove 511 from the thrust plate 5 shown in FIG.

  Between the female screw portion 3111 and the screw 16 and between the female screw portion 3112 and the male screw portion 51 are sealed with adhesives 91 and 92, respectively, and the lubricating oil filled in the bearing mechanism 4c is shaft. Leakage from 311 is prevented. Other configurations are the same as those of the motor 10 according to the first embodiment.

  In the motor 10a, as in the motor 10 described above, the rotation direction of the rotor portion 3 is counterclockwise when the motor 10a is viewed in plan, and a right-hand screw is adopted as the screw 16. In other words, the screw 16 has a rotational direction opposite to the rotational direction of the motor 10a (viewed from above) to be screwed into the female screw portion 3111. Further, a left-hand screw is employed for the male screw portion 51 of the thrust plate 5d, and when the motor 10a is viewed from the lower side, the rotation direction of the motor 10a is clockwise, so the male screw portion 51 is viewed from the lower side. The direction of rotation opposite to the direction of rotation of the motor 10a is the direction screwed into the female screw portion 3112. By adopting the left screw, the male screw portion 51 is prevented from loosening from the female screw portion 3112 when vibration is applied during startup and stop of the motor 10a or during rotation.

  Although the embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and various modifications can be made.

  In the above embodiment, a left screw is employed as the male screw portion 51. However, a right screw is employed as the male screw portion 51 in the case of a motor that rotates clockwise when viewed in plan. Generally speaking, the rotation direction opposite to the rotation direction of the motor when viewed from the bottom surface is the direction in which the male screw portion is screwed into the female screw portion, so that the male screw portion 51 becomes the female screw portion. The loosening from 3112 is prevented. Further, the female screw portion 3111 provided at the upper end of the shaft 311 and the screw 16 screwed into the female screw portion 3111 are described as being right-hand screws, but may be left-hand screws.

  In the first and third embodiments, the flow path 72 is formed by providing the groove 511 in the male screw portion 51. However, instead of the groove 511 or together with the groove 511, the central axis J1 is formed on the female screw portion 3112. The flow path 72 may be provided by forming a groove along the line. Even if the groove 511 does not exist, the groove 511 may be omitted because there is a slight gap along the screw thread in the region between the male screw portion 51 and the female screw portion 3112. Even in this case, the region between the male screw portion 51 and the female screw portion 3112 and the outside of the shaft 311 are communicated with each other by the flow channel 71, and the flow channel 71, the male screw portion 51 and the female screw portion are communicated from the lower gap 63. Lubricating oil can be filled up to the space 73 via the region between 3112 and the foreign matter can be accumulated between the shaft 311 and the thrust plate 5 or the like. The flow path 71 does not necessarily have to be formed by a groove-shaped recess. For example, a diameter is provided by providing a protrusion on the lower end surface 3113 of the shaft 311 or simply providing a gap between the lower end surface 3113 and the disc portion 52. A directional flow path may be secured.

  Moreover, although it demonstrated that the groove | channel 511 of the external thread part 51, the groove | channel 521 (refer FIG. 10) formed in the disc part 52, and the groove | channel 3114 (refer FIG. 7) formed in the shaft 311 were each four, Other numbers may be adopted.

  In the third embodiment, a flow path is formed by a groove 521 provided in the disc portion 52 of the thrust plate 5a as shown in FIG. May be.

  In the bearing mechanism according to the above embodiment, the thrust dynamic pressure bearing portion is provided also in the upper gap 61 as shown in FIGS. 3 and 4, but by providing the thrust dynamic pressure groove on the upper end surface of the sleeve housing 41. A thrust dynamic pressure bearing portion may be formed between the disc portion 312 of the rotor hub 31 and the sleeve housing 41. Further, the shape of the thrust dynamic pressure groove 4241 formed on the lower end surface 424 of the sleeve 42 may be a herringbone shape.

  Further, the shaft 311 (or the shaft 311a) constituting the radial dynamic pressure bearing portion in the side gap 62 may be formed as a member separate from the rotor hub 31. The sleeve housing 41 may be a single member with the base bracket 21. In this case, the sleeve housing 41 is integrally fixed to the base bracket 21 of the stator portion 2. The bottomed cylindrical sleeve housing 41 may be composed of a cylindrical member and a closing member that is a separate member from the cylindrical member and closes the lower end of the cylindrical member.

  The motor according to the above embodiment does not necessarily have to be a so-called outer rotor type in which the field magnet 32 is disposed outside the armature 22, and the field magnet 32 is on the central axis J1 side of the armature 22. It may be an inner rotor type disposed in the. The motor may be used as a drive source for a recording disk drive device other than the hard disk device (for example, a removable disk device or a read-only device from the recording disk). Furthermore, it may be used as a motor other than the drive source of the recording disk drive device.

1 is a cross-sectional view of a recording disk drive device according to a first embodiment. It is sectional drawing of a motor. It is sectional drawing which expands and shows a part of motor. It is a top view of a sleeve. It is sectional drawing of a sleeve. It is a bottom view of a sleeve. It is a bottom view of a shaft. It is a top view of a thrust plate. It is a figure which expands and shows the lower part of a bearing mechanism. It is a top view of the thrust plate of the bearing mechanism which concerns on the other example of 1st Embodiment. It is a figure which expands and shows the lower part of a bearing mechanism. It is sectional drawing of the thrust plate of the bearing mechanism which concerns on 2nd Embodiment. It is a figure which expands and shows the lower part of a bearing mechanism. It is a figure which expands and shows the lower part of the bearing mechanism which concerns on 3rd Embodiment. It is a figure which shows the bearing mechanism which concerns on 4th Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Recording disk drive device 2 Stator part 3 Rotor part 4, 4a, 4b Bearing mechanism 5, 5a-5d Thrust plate 10, 10a Motor 11 Recording disk 12 Access part 13 Housing 41 Sleeve housing 42 Sleeve 51 Male screw part 52 Disc part 53 Through-hole 63 Lower gap 71, 71a, 72 Flow path 73 Space 311 Shaft 421 (Sleeve) outer peripheral surface 424 (Sleeve) lower end surface 3112, 3111 Female thread portion 3113 (Shaft) lower end surface J1 Central axis

Claims (11)

A bearing mechanism that uses fluid dynamic pressure for a motor,
A shaft,
A sleeve in which the shaft is inserted and a radial dynamic pressure bearing portion is formed between the shaft and the shaft via lubricating oil;
A thrust plate attached to one end of the shaft and facing the end surface of the sleeve;
A cylindrical sleeve housing with a bottom that covers the outer peripheral surface of the sleeve and the thrust plate and holds lubricating oil around the thrust plate;
With
The thrust plate is
The one end of the shaft is screwed into a female screw portion formed along a central axis, and the direction of rotation opposite to the one direction in which the shaft rotates relative to the sleeve is screwed into the female screw portion. A male screw part that is in the direction to be
A disk part that spreads outward from the male thread part around the central axis and faces the end face of the sleeve, and forms a thrust dynamic pressure bearing part between the end face via lubricating oil;
A bearing mechanism comprising: The bearing mechanism according to claim 1,
A bearing mechanism in which a hole in which the female screw portion is formed does not penetrate the shaft. The bearing mechanism according to claim 2,
The bearing mechanism, wherein the thrust plate is fixed to the shaft only by screwing the male screw portion into the female screw portion. The bearing mechanism according to claim 3,
Between the one end of the shaft and the disc portion, a flow path is provided that communicates a region between the male screw portion and the female screw portion and the outside of the shaft,
The female screw part is formed from the gap between the end surface of the sleeve and the disk part via the flow path and the region between the male screw part and the female screw part. A bearing mechanism characterized in that lubricating oil is continuously filled up to the inside of the hole. The bearing mechanism according to claim 4,
The bearing mechanism is characterized in that another flow path connecting the flow path and the inside of the hole is provided between the male screw portion and the female screw portion. The bearing mechanism according to claim 4 or 5,
The thrust mechanism has a through hole that penetrates the male screw part and the disk part along the central axis. The bearing mechanism according to claim 3,
The thrust mechanism has a through hole penetrating the male screw part and the disk part along the central axis. A bearing mechanism according to any one of claims 4 to 7,
The bearing mechanism is characterized in that the thrust plate is made of a material having a lower coefficient of thermal expansion than the shaft. A bearing mechanism according to any one of claims 2 to 8,
Another female thread portion is formed along the central axis at the other end of the shaft,
2. A bearing mechanism according to claim 1, wherein a spiral of a screw thread is reverse in the female screw portion at the one end and the other female screw portion at the other end. An electric motor,
A bearing mechanism according to any one of claims 1 to 9,
A rotor portion attached to the other end opposite to the one end of the shaft;
A stator portion to which the sleeve housing is fixed;
A motor comprising: A recording disk drive device comprising:
The motor according to claim 10, wherein the motor rotates a recording disk;
An access unit for reading and / or writing information on the recording disk;
A housing for housing the motor and the access unit;
A recording disk drive device comprising:

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