JP2010127448A - Fluid dynamic-pressure bearing mechanism, motor, recording disk driving device, and method for producing fluid dynamic-pressure bearing mechanism - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To accurately and easily check the position of the interface of a lubricating oil in a fluid dynamic pressure mechanism utilizing a fluid dynamic pressure. <P>SOLUTION: The bearing mechanism 4 of a motor 1 used in a recording disk driving device includes a shaft 41, a bearing 42 being part of a rotor body and seal members 43a and 43b. A lubricating oil 10 is filled between the shaft 41 and the bearing 42. A tapered gap 45 whose width is gradually extended toward the opening side is formed between the outer inclined surface 4112 of the annular member 411 of the shaft 41 and the inner surface 4321 of the seal member 43. The diameters of the outer inclined surface 4112 and the inner surface 4321 are gradually reduced toward the opening side. The interface 11 of the lubricating oil 10 is formed in the tapered gap 45. The seal member 43 has a light translucency, whereby the position of the interface 11 of the lubricating oil 10 can accurately and easily be checked from the diametrical outside. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a fluid dynamic bearing mechanism used in an electric motor.

  A spindle motor used in a recording disk drive device or the like uses a fluid dynamic bearing mechanism in which a shaft is rotatably supported via a lubricating oil filled between the shaft and a sleeve. Conventionally, in a fluid dynamic pressure bearing mechanism, it is inspected whether an appropriate amount of lubricating oil is injected into the fluid dynamic pressure bearing mechanism at the time of manufacturing a motor.

  For example, in the hydrodynamic bearing motor disclosed in Patent Document 1, a see-through plate made of a translucent material is attached to a hole provided in the hub, and the motor completes oil leakage from the bearing portion. Even so, it can be observed. Further, Patent Document 2 discloses a working fluid amount inspection method in which a working fluid filling state is confirmed by visual recognition or imaging through a translucent cover that covers an upper end surface of a sleeve of a hydrodynamic bearing device. Patent Document 3 discloses a hydrodynamic bearing spindle motor in which the cover plate facing the thrust plate is formed of a transparent material, so that the amount of lubricating oil can be confirmed by observing the inside of the thrust bearing. Yes.

In the method of manufacturing a hydrodynamic bearing device disclosed in Patent Document 4, the position of the bearing end surface and the liquid level of the lubricating oil in the axial direction is obtained by an automatic focusing device that obtains the in-focus position from an image obtained from a microscope. The position of the lubricating oil level is adjusted.
JP 2001-327125 A JP 2006-170230 A JP 2000-291660 A JP 2001-90733 A

  By the way, causes of leakage of the lubricating oil include external forces such as vibration, impact, centrifugal force and gravity, wet diffusion, expansion of the lubricating oil due to changes in atmospheric pressure and temperature, generation of bubbles, and the like. In a capillary seal that forms an interface in the taper gap to hold the lubricating oil, the gap is preferably narrowed to increase the capillary force, and the gap is preferably deepened to allow the interface to change due to expansion of the lubricating oil.

  However, when the interface of the lubricating oil is observed from above the seal portion through the transparent member, it is difficult to observe the interface if the gap is inclined with respect to the central axis or the gap is deep. This makes it impossible to obtain an accurate interface height.

  The present invention has been made in view of the above problems, and has as its main object to accurately and easily confirm the position of the interface of the lubricating oil in a fluid dynamic pressure bearing mechanism that uses fluid dynamic pressure.

  The invention according to claim 1 is a fluid dynamic pressure bearing mechanism used for an electric motor, and is inserted into the bearing portion and the bearing portion, and rotates relative to the bearing portion. A shaft portion supported by the bearing portion using the fluid dynamic pressure of the lubricating oil generated in the bearing gap between the inner surface of the bearing portion, and a gradual width toward the opening around the shaft portion An annular taper gap that increases, and a seal member that prevents leakage of the lubricating oil by forming an interface of the lubricating oil continuous from the bearing gap in the tapered gap, and on both sides of the tapered gap The inner diameter of each surface gradually decreases toward the opening side, and the seal member is formed of a translucent material that makes the interface of the lubricating oil visible from the radially outer side.

  The invention according to claim 2 is the fluid dynamic pressure bearing mechanism according to claim 1, wherein the seal member has a mark in the vicinity of a position where the interface is visually recognized.

  The invention according to claim 3 is the fluid dynamic bearing mechanism according to claim 1 or 2, wherein the lubricating oil is colored.

  The invention according to claim 4 is the fluid dynamic pressure bearing mechanism according to claim 1 or 2, wherein the lubricating oil contains a fluorescent agent.

  A fifth aspect of the present invention is the fluid dynamic pressure bearing mechanism according to any one of the first to fourth aspects, wherein the seal member has an annular lid portion that covers the opening of the tapered gap.

  The invention according to claim 6 is an electric motor, wherein the fluid dynamic pressure bearing mechanism according to any one of claims 1 to 5 and a stator portion to which one of the bearing portion and the shaft portion is fixed. And a rotor portion fixed to the other of the bearing portion and the shaft portion.

  The invention according to claim 7 is a recording disk drive device, wherein the motor according to claim 6 rotates the recording disk, an access unit for reading or writing information on the recording disk, the motor and the motor A housing for housing the access portion.

  The invention according to claim 8 is a method of manufacturing a fluid dynamic pressure bearing mechanism used for an electric motor, wherein a) a step of inserting a shaft portion into the bearing portion, and b) an annular shape having translucency. By inserting the shaft portion into the seal member, an annular gap whose width gradually increases toward the opening side around the shaft portion, and the respective inner diameters of both side surfaces gradually decrease toward the opening side. Forming a taper gap; and c) filling the bearing gap between the inner surface of the bearing portion and the shaft portion with lubricating oil, and providing an interface of the lubricating oil continuous from the bearing gap in the taper gap. And d) a step of confirming the position of the interface in the axial direction from the outside in the radial direction of the seal member.

  A ninth aspect of the present invention is the method of manufacturing a fluid dynamic bearing mechanism according to the eighth aspect, wherein, in the step d), the position of the interface of the lubricating oil is a circumference of the outer surface of the seal member. Confirmed at 3 or more positions in the direction.

  A tenth aspect of the present invention is a method of manufacturing the fluid dynamic pressure bearing mechanism according to the eighth or ninth aspect, wherein e) a step of reducing the pressure around the fluid dynamic pressure bearing mechanism; and f) the seal member. And a step of confirming the position of the interface in the axial direction from the outside in the radial direction.

  In the present invention, the position of the interface of the lubricating oil can be accurately and easily confirmed from the radially outer side of the seal member that forms the tapered gap in the fluid dynamic pressure bearing mechanism that uses fluid dynamic pressure. In the second aspect of the present invention, the suitability of the interface position can be easily confirmed by the mark, and in the third and fourth aspects of the present invention, the confirmation of the interface position can be further facilitated.

  According to the ninth aspect of the present invention, it is possible to more accurately confirm whether or not the lubricating oil has been properly filled by confirming the positions of the interfaces at a plurality of positions in the circumferential direction. In this invention, the presence or absence of bubbles in the lubricating oil can be easily confirmed.

  FIG. 1 is a longitudinal sectional view of a recording disk drive device 5 including an electric spindle motor (hereinafter referred to as “motor”) according to an embodiment of the present invention. The recording disk drive 5 is a so-called hard disk drive, and holds three disk-shaped recording disks 51 for recording information, an access unit 52 for reading and writing information to the recording disks 51, and a recording disk 51. An electric motor 1 that rotates, and a housing 53 that houses the recording disk 51, the motor 1, and the access unit 52 in the internal space are provided.

  The housing 53 has an opening in the upper part, and the first housing member 531 having a lidless box shape to which the motor 1 and the access unit 52 are attached to the inner bottom surface, and a plate-like second housing that covers the opening of the first housing member 531. A member 532 is provided. In the recording disk drive device 5, the second housing member 532 is joined to the first housing member 531 to form the housing 53, and the internal space is a clean space with extremely little dust and dirt.

  The three recording disks 51 have an annular spacer disposed between them, and the motor 1 is fitted into the central hole, and is fixed to the motor 1 by a clamper 54 and a plurality of screws 55. The access unit 52 is provided with a plurality of heads 521 that magnetically read and write information in the vicinity of the recording disk 51, an arm 522 that supports each head 521, and the head 521 is moved by moving the arm 522. 51 and a head moving mechanism 523 that moves relative to the motor 1. With these configurations, the head 521 accesses a required position of the recording disk 51 in the state of being close to the rotating recording disk 51, and writes and reads information.

  FIG. 2 is a longitudinal sectional view of the motor 1. The motor 1 is an outer rotor type motor, and includes a stator portion 2 that is a fixed assembly, a rotor portion 3 that is a rotary assembly, and a fluid dynamic bearing mechanism 4 (hereinafter referred to as “bearing mechanism 4”). The shaft portion 41 of the bearing mechanism 4 is fixed to the stator portion 2, and the rotor portion 3 into which the shaft portion 41 is inserted is located with respect to the stator portion 2 around the central axis J <b> 1 of the motor 1 via the bearing mechanism 4. It is rotatably supported. Hereinafter, although 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, the central axis J1 does not necessarily coincide with the direction of gravity.

  The stator portion 2 has a hole 211 at the center, a base bracket 21 to which the lower end of the shaft portion 41 is fixed, an annular stator 22 fixed to the base bracket 21, and a hole on the lower surface side of the base bracket 21. A plate 23 that closes the portion 211 is provided. The rotor portion 3 includes a substantially cylindrical rotor body 31, a cylindrical portion 32 protruding downward from the outer edge portion of the rotor body 31, a cylindrical metal yoke 33 attached to the inner surface of the cylindrical portion 32, and the yoke 33. The field magnet 34 is attached to the inner side surface. The upper and lower openings of the rotor body 31 have a first inclined bearing surface 311 having a conical shape (to be precise, the shape of the side surface of the truncated cone; the same applies hereinafter) whose diameter gradually increases from the inside toward the opening side. Is provided. In the motor 1, a current is supplied from an external power source to the coil of the stator 22, whereby torque is generated between the stator 22 and the field magnet 34, and the rotor portion 3 rotates about the central axis J <b> 1.

  The bearing mechanism 4 includes a shaft portion 41 inserted into a hole portion of the rotor main body 31, and annular seal members 43a and 43b attached to upper and lower openings of the rotor main body 31, and the shaft portion 41 includes the shaft main body 412, and And an annular member 411 attached to the upper end portion and the center portion of the shaft body 412. Further, a portion in the vicinity of the central through hole of the rotor body 31 (hereinafter referred to as “bearing portion 42”) is a part of the bearing mechanism 4 as a portion that supports the shaft portion 41. That is, in the motor 1, the bearing portion 42 of the rotor body 31 serves as a part of the rotor portion 3 and a part of the bearing mechanism 4, and the rotor portion 3 is substantially fixed to the bearing portion 42 of the bearing mechanism 4. It has a structure.

  An annular member 411 attached to the upper end of the shaft body 412 has a second inclined bearing surface 4111 facing the first inclined bearing surface 311 at a portion located in the rotor body 31 and protrudes upward from the rotor body 31. An outer inclined surface 4112 is provided at a portion to be operated. Similar to the first inclined bearing surface 311, the second inclined bearing surface 4111 has a conical shape whose diameter increases from the opening side of the rotor body 31 (that is, from the lower side to the upper side), and has a herringbone-like dynamic pressure on the surface. Grooves are formed. Further, the outer inclined surface 4112 has a conical shape whose diameter decreases upward.

  The annular member 411 attached to the central portion of the shaft main body 412 is upside down from that attached to the upper end portion, and the others are the same. That is, it has a conical second inclined bearing surface 4111 facing the first inclined bearing surface 311 and an outer inclined surface 4112 projecting downward. In the bearing mechanism 4, the second inclined bearing surface 4111 of the upper and lower annular members 411 is in contact with the first inclined bearing surface 311, so that the movement of the rotor portion 3 in the direction along the central axis J <b> 1 with respect to the shaft portion 41 is limited. The

  Lubricating oil 10 is filled between the bearing portion 42 and the shaft portion 41 and between the shaft portion 41 and the seal members 43a and 43b, and when the motor 1 rotates, the first inclined bearing surface 311 and the second inclined surface. Fluid dynamic pressure using the lubricating oil 10 as a working fluid is generated in two bearing gaps 44 formed between the bearing surface 4111 and the rotor portion 3 can rotate around the central axis J1 with respect to the stator portion 2. Supported by

  3 is a view showing a vertical cross section of the upper seal member 43a on the right side of the central axis J1 in FIG. 2, and FIG. 4 is an enlarged view showing the vicinity of the upper seal member 43a of the bearing mechanism 4. As shown in FIG. The structure in the vicinity of the lower seal member 43b is substantially the same as that in FIG. 4 except that the structure is upside down. As shown in FIGS. 3 and 4, the seal member 43a has a conical side portion 432 whose diameter decreases upward, and has an annular shape that continues inward from the upper end of the side portion 432, and the shaft portion 41 penetrates in the center. A lid portion 431 having a hole portion to be formed, and an annular attachment portion 433 extending radially outward from the lower end of the side portion 432, and the seal member 43 a is fixed to the upper surface of the bearing portion 42 by the attachment portion 433. The portion of the annular member 411 protruding from the bearing portion 42 is covered with the seal member 43a in FIG. 4, and both the inner side surface 4321 and the outer side surface 4322 of the side portion 432 are inclined surfaces whose diameters become smaller upward. Is done. In the cross section including the central axis J1, the inclination angle of the inner side surface 4321 with respect to the central axis J1 is smaller than the inclination angle of the outer inclined surface 4112 of the annular member 411 with respect to the central axis J1.

  Further, the seal member 43a is formed of a light-transmitting material, and as shown in FIG. 3, the outer surface 4322 of the side portion 432 is provided with two protrusions 434 that are marks arranged in the vertical direction. As the light-transmitting material, resin (methylpentene polymer (TPX (registered trademark)), polyetherimide (PEI), polyamide (PA), polyethylene (PE), polypropylene (PP), polyoxymethylene (POM), Polybutylene terephthalate (PBT) or the like) or glass is used. The lower seal member 43b shown in FIG. 2 is substantially the same as the upper seal member 43a except that the lid portion 431 is not provided.

  As shown in FIG. 4, an annular taper gap 45 is formed between the outer inclined surface 4112 of the annular member 411 and the side portion 432 of the seal member 43a, and the width of the taper gap 45 is the opening side (that is, FIG. 4). And the lubricating oil 10 is held inside the taper gap 45. The taper gap 45 communicates with the bearing gap 44 at the lower portion, and the lubricating oil 10 is also continued from the bearing gap 44. As described above, the inner diameters of both side surfaces of the taper gap 45 (that is, the outer inclined surface 4112 and the inner side surface 4321 of the side portion 432) gradually decrease toward the opening side of the taper gap 45.

  An interface 11 of the lubricating oil 10 is formed in the taper gap 45, and leakage of the lubricating oil 10 is prevented by a capillary force acting toward the inside of the bearing gap 44. Further, when the motor 1 rotates, a force directed toward the inside of the bearing gap 44 acts on the lubricating oil 10 in the taper gap 45 by centrifugal force. In the taper gap 45, since the seal member 43a is formed of a light-transmitting material, the interface 11 of the lubricating oil 10 is visible from the outside in the radial direction of the seal member 43a.

  FIG. 5 is a diagram showing a flow of manufacturing a part of the motor 1 including the bearing mechanism 4. In manufacturing the motor 1, first, the shaft body 412 is inserted into the hole of the rotor body 31 (see FIG. 1), and the annular member 411 is fixed to the shaft body 412 by press-fitting at the upper and lower openings of the rotor body 31. As a result, the shaft portion 41 is inserted into the bearing portion 42 (step S11). The seal member 43a is attached to the upper surface of the bearing portion 42 while the shaft portion 41 is inserted into the seal member 43a, and a taper gap 45 is formed around the shaft portion 41 as shown in FIG. Further, a seal member 43b is attached to the lower surface of the bearing portion 42 in a direction opposite to that of FIG. 4, and a taper gap similar to the taper gap 45 shown in FIG. 4 is formed around the shaft portion 41 (step). S12). Further, the lubricating oil 10 flows from the gap between the lower seal member 43 b and the shaft portion 41 to the gap including the two bearing gaps 44 between the inner surface of the bearing portion 42 of the rotor body 31 and the shaft portion 41. Filled and the interface 11 (see FIG. 4) of the lubricating oil 10 continuing from the bearing gap 44 is formed in the two taper gaps 45 (step S13). In the following description, the assembly of the rotor main body 31 and the shaft portion 41 at this stage is referred to as a “bearing assembly”.

  Next, the bearing assembly is placed on the interface measuring device 6 shown in FIG. 6 with the central axis J1 parallel to the direction of gravity, and the interface 11 (see FIG. 4) of the lubricating oil 10 is confirmed. The interface measuring device 6 includes a rotating mechanism 61 that holds the bearing assembly rotatably about the central axis J1, a camera 62 that images the interface 11 from the radially outer side of the seal member 43a toward the central axis J1, and a rotating mechanism 61. And a control unit 63 that acquires a measurement result from an image acquired by the camera 62. In order to facilitate the confirmation of the interface 11, the lubricating oil 10 is preferably colored or contains a fluorescent agent.

  The calculation unit 631 of the control unit 63 performs image processing on the image acquired by the camera 62, and a boundary line (the highest meniscus) indicating the position of the end of the interface 11 indicated by reference numeral H1 in FIG. Position, and the boundary line between the lubricating oil 10 and air on the inner surface 4321 of the seal member 43a is detected. Thereby, the interface position H1 is acquired as a position in a direction parallel to the central axis J1 of the interface 11 (hereinafter referred to as “axial direction”). Then, the calculation unit 631 determines whether or not the filling amount of the lubricating oil 10 is appropriate based on whether or not the interface position H1 is between the two protrusions 434 shown in FIG. 3 (that is, the interface position H1 is (Step S14). The appropriate interface position H1 is set so that the lubricating oil 10 does not leak and the lubricating oil 10 in the bearing mechanism 4 is not short in consideration of evaporation loss of the lubricating oil 10.

  As the position of the interface 11, the position of the bottom (the lowest part in the axial direction) of the interface 11 indicated by reference numeral H <b> 2 in FIG. 4 may be adopted instead of the interface position H <b> 1. Even when the lubricating oil 10 is colored, the width of the meniscus in the radial direction is very small, and the interface position H2 can be detected. Further, even when the lubricating oil 10 is colorless and transparent, the interface 11 can be confirmed. Even in this case, the position of the interface 11 can be confirmed at the interface position H1 or the interface position H2.

  When the first measurement is completed, the rotation mechanism 61 rotates the bearing mechanism 4 to move the measurement position in the circumferential direction around the central axis J1 (hereinafter simply referred to as “circumferential direction”) (step S15, (S16) The second measurement is performed in the same manner, and the interface position H1 is acquired again (step S14). The measurement is repeated while changing the measurement position in the circumferential direction until the measurement is completed at all measurement positions (step S15). Accordingly, the interface position H1 is confirmed at three or more positions in the circumferential direction on the outer surface 4322 of the seal member 43a.

  FIG. 7 is a view showing a cross section including the central axis J1 of the peripheral portion of the seal member 43a, and shows that the interface position H1 is different in the circumferential direction when the central axis of the shaft portion 41 and the seal member 43a is deviated. ing.

  When the coaxiality between the shaft portion 41 and the seal member 43a is not obtained, the radial width of the taper gap 45 is not constant in the circumferential direction. Since the interface 11 of the lubricating oil 10 is formed at a position where the capillary force is balanced, in this case, the height of the interface 11 is different in the circumferential direction, and the lubricating oil 10 can leak at a location where the distance to the opening is short. It will be high. In FIG. 7, the highest interface position H1 in the axial direction is shown on the left side of the shaft portion 41, the lowest interface position H1 is shown on the right side, and the difference in height between the highest interface position H1 and the lowest interface position H1 is denoted by D. Is shown. When the acquired number of measurement of the interface position H1 is sufficiently large, the difference between the maximum and minimum of them is the difference D in height of the interface 11, and when the number of measurements is small, the measured interface position H1 The entire interface position H1 in the circumferential direction is obtained by interpolation, and a difference D between the maximum value and the minimum value of the interface position H1 is obtained.

  FIG. 8 is a reference diagram showing the shape of the interface 11 in plan view when the coaxiality between the shaft portion 41 and the seal member 43a is not obtained. Actually, the interface 11 cannot be viewed in plan by the seal member 43a. The region shown with parallel diagonal lines is the interface 11, the inner ellipse indicates the boundary between the outer inclined surface 4112 of the annular member 411 and the interface 11, and the outer ellipse indicates the inner surface 4321 of the seal member 43 a and the interface 11. Indicates the boundary. Since the taper gap 45 is inclined with respect to the axial direction as shown in FIG. 7, if the interface position H1 in the axial direction is different in the circumferential direction, the shape of the interface 11 when seen in plan view as shown in FIG. It becomes elliptical.

  In the interface measuring device 6, a table indicating the height difference D of the interface 11 corresponding to the degree of coaxiality between the shaft portion 41 and the seal member 43a is prepared in advance, and by referring to the table in the calculation unit 631, The coaxiality between the shaft portion 41 and the seal member 43a is obtained (step S17). When it is confirmed that the filling amount of the lubricating oil 10 is appropriate and sufficient coaxiality is obtained, the bearing assembly is removed from the interface measuring device 6, and the lower end portion of the shaft portion 41 is the stator portion. 2 (see FIG. 2) (step S18). When the coaxiality is not sufficient, the seal member 43a is replaced and the lubricating oil is refilled, and the operations after step S14 are performed again.

  Although omitted in FIG. 5, the interface measurement is also performed on the lower seal member 43b. At this time, the bearing assembly is placed on the interface measuring device 6 by turning upside down, and a minute mirror is arranged near the outer surface of the seal member 43b, and the interface 11 is imaged by the camera 62 from above via the mirror. The Further, based on the height of the interface 11 obtained through the lower seal member 43b, the coaxiality between the shaft portion 41 and the seal member 43b is obtained.

  As described above, in the bearing mechanism 4, the side portions 432 of the seal members 43 a and 43 b are formed of a translucent material, so that the lubricating oil 10 can be removed from the radially outer side of the seal members 43 a and 43 b. The interface 11 can be confirmed, and the position of the interface 11 in the axial direction can be confirmed more accurately and easily than in the case of confirming from the axial direction. In particular, both inner side surfaces of the taper gap 45 gradually decrease in diameter toward the opening side, and even when it is difficult to confirm the interface 11 from above, the bearing mechanism 4 is not tilted from the radially outer side. The interface 11 can be easily confirmed. Further, even when the opening of the taper gap 45 is covered by the lid portion 431 like the seal member 43a, the position of the interface 11 can be confirmed.

  Furthermore, by forming the protruding portion 434 as a mark on the side portion 432 in the seal member 43a, it is possible to more easily confirm whether the position of the interface 11 is appropriate. When the lubricating oil 10 contains a colorant or a fluorescent agent, confirmation of the position of the interface 11 can be further facilitated.

  In the measurement of the interface position H1 (or H2, the same applies hereinafter), the interface position H1 is acquired at three or more positions in the circumferential direction of the outer surface 4322 of the seal members 43a and 43b, so that the interface position H1 in the circumferential direction is obtained. A change can be acquired and it can be confirmed more correctly whether filling of lubricating oil 10 was performed appropriately. It is also possible to obtain the coaxiality between the shaft portion 41 and the seal members 43a and 43b from the change in the circumferential direction of the interface position H1.

  By confirming the coaxiality, it is not necessary to take measures to increase the taper gap 45 in the axial direction and to keep the interface position H1 away from the opening in order to surely prevent the lubricating oil 10 from leaking. can do. Further, the shape measurement of the outer surface 4322 of the seal member 43a cannot detect the abnormality of the taper gap 45 due to the variation in the thickness of the side portion 432. However, by acquiring the change in the circumferential direction of the interface position H1, Such abnormalities can also be detected.

  FIG. 9 is a view showing another example of the interface measuring device, and the interface measuring device 6a of FIG. 9 is compared with the interface measuring device 6 of FIG. 6 with a vacuum pump 65 connected to the vacuum chamber 64 and the vacuum chamber 64. The other points are the same, and the same components are denoted by the same reference numerals. In the interface measuring device 6 a, the rotation mechanism 61 and the camera 62 are disposed in the decompression chamber 64.

  FIG. 10 is a view showing a part of the manufacturing flow of the motor 1 using the interface measuring device 6a, and shows steps S21 to S25 performed in place of steps S14 to S16 in the manufacturing flow shown in FIG. . In the manufacturing flow shown in FIG. 10, when step S13 is performed and the bearing assembly is filled with lubricating oil, the bearing assembly is placed on the rotating mechanism 61 in the decompression chamber 64 as shown in FIG. (Step S21). Then, the interface measurement of the bearing assembly is performed in the same manner as Steps S14 to S16 in FIG. 5 in a state under the atmospheric pressure before the decompression chamber 64 is decompressed (Step S22).

  When interface measurement is performed at all positions in the circumferential direction, the inside of the decompression chamber 64 (that is, around the bearing assembly including the bearing mechanism 4) is decompressed using the vacuum pump 65 (step S23), and step S14 is performed again. In the same manner as in S16, the interface 11 is measured from the radially outer side of the seal member 43a (step S24). And the interface position acquired in step S22 and the interface position after pressure reduction are compared (that is, the position of the interface 11 in the axial direction is confirmed). If bubbles remain in the lubricating oil 10 of the bearing assembly, the bubbles expand due to the reduced pressure and the interface 11 rises, so the presence or absence of bubbles can be confirmed by the above operation (step S25).

  When the interface measurement is completed, the decompression chamber 64 is returned to normal pressure. If the presence of air bubbles is confirmed, the bearing assembly is refilled with lubricating oil. When there are no bubbles in the lubricating oil 10, the calculation unit 631 of the control unit 63 obtains the coaxiality between the shaft portion 41 and the seal member 43a based on the interface position H1 measured at normal pressure (step S17). . Then, if the bearing assembly is taken out from the decompression chamber 64 and sufficient coaxiality is obtained, the shaft portion 41 of the bearing assembly is attached to the stator portion 2 (step S18). If the coaxiality is not sufficient, the seal member 43a is replaced and the lubricating oil is refilled, and the operations after step S21 are performed again.

  Although omitted in FIG. 10, the measurement of the interface under atmospheric pressure is performed on the lower seal member 43b by turning the bearing assembly upside down. At this time, a minute mirror is disposed in the vicinity of the outer surface of the seal member 43b, and the interface 11 is imaged by the camera 62 from above through the mirror. Further, the coaxiality between the shaft portion 41 and the seal member 43b is obtained based on the height of the interface 11 obtained through the lower seal member 43b.

  As described above, in the interface measuring device 6a, by using the seal members 43a and 43b formed of a translucent material, the interface 11 of the lubricating oil 10 is formed from the radially outer side of the seal members 43a and 43b. The position of the interface 11 in the axial direction can be confirmed accurately and easily compared to the case of confirming from the axial direction. Further, by confirming the interface 11 in the decompression chamber 64, the presence or absence of bubbles in the lubricating oil 10 can be easily confirmed. Further, as in FIGS. 7 and 8, the change in the circumferential direction of the interface position H1 can be acquired, and whether or not the lubricating oil 10 is properly filled can be confirmed more accurately and the shaft portion. The coaxiality of 41 and the sealing members 43a and 43b can be confirmed.

  FIG. 11 is an enlarged view showing a part of a bearing mechanism 4a according to another example. Compared with the bearing mechanism 4 shown in FIG. 2, the bearing mechanism 4 a omits the first inclined bearing surface 311 of the rotor main body 31 (that is, the hole of the rotor main body 31 is cylindrical), and the annular shape of the shaft portion 41. The member 411 is an annular member 411a having a different shape. The other structure of the bearing mechanism 4a is substantially the same as that of the bearing mechanism 4, and the same reference numerals are given to the same structures. In addition, the first inclined bearing surface 311 is omitted on the lower side of the rotor body 31, and an annular member 411 a that is turned upside down is provided, and the rest is the same as the bearing mechanism 4.

  The annular member 411a is only a truncated cone-shaped portion (that is, the upper half) protruding upward from the bearing portion 42 of the annular member 411 shown in FIG. 4 and has a lower surface 4113 facing the upper surface of the rotor body 31. . Herringbone-like dynamic pressure grooves are formed on the lower surface 4113, and fluid dynamic pressure of the lubricating oil 10 is generated in the thrust bearing gap 46 between the lower surface 4113 and the upper surface of the rotor body 31 when the rotor portion 3 rotates. To do. In the annular member 411 a located on the lower side of the rotor body 31, fluid dynamic pressure is similarly generated in the thrust bearing gap 46. Thus, upper and lower thrust bearing portions that support the rotor portion 3 in the thrust direction with respect to the shaft portion 41 are formed. Further, a herringbone-shaped dynamic pressure groove is formed on the outer surface of the shaft body 412 in the circumferential direction, and a radial bearing between the shaft body 412 and the inner surface of the bearing portion 42 when the motor 1 (see FIG. 2) rotates. A fluid dynamic pressure of the lubricating oil 10 is generated in the gap 47. Thereby, the radial bearing part which supports the rotor part 3 in the radial direction with respect to the shaft part 41 is formed.

  Also in the bearing mechanism 4a of FIG. 11, between the outer inclined surface 4112 of the annular member 411a and the side portion 432 of the seal member 43a, the width gradually increases toward the opening side, and the lubricating oil 10 is held inside. An annular taper gap 45 is formed. The taper gap 45 continues from the thrust bearing gap 46, and the lubricating oil 10 also continues from the thrust bearing gap 46. An interface 11 of the lubricating oil 10 is formed in the taper gap 45, and leakage of the lubricating oil 10 is prevented by capillary force. Further, the inner diameters of both side surfaces of the taper gap 45 (that is, the outer inclined surface 4112 and the inner side surface 4321 of the side portion 432) are gradually reduced toward the opening side of the taper gap 45, and the motor 1 is centrifuged when the motor 1 rotates. A force toward the thrust bearing gap 46 acts on the lubricating oil 10 in the taper gap 45 due to the force.

  Furthermore, the seal member 43a is formed of a light-transmitting material, and the interface 11 of the lubricating oil 10 is visible from the radial outside of the seal member 43a. Thereby, the interface 11 of the lubricating oil 10 can be confirmed from the radially outer side of the seal members 43a and 43b, and the axial position of the interface 11 can be confirmed more accurately and easily than when the interface 11 is viewed from the axial direction. can do. Further, two protrusions 434 arranged in the vertical direction as marks are formed on the side portions 432 of the seal members 43a and 43b, so that the suitability of the position of the interface 11 can be more easily confirmed.

  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.

  The taper gap 45 is formed around the shaft portion 41 and may have any other structure as long as it holds the lubricating oil 10 by utilizing capillary force and centrifugal force. For example, a member that forms the bearing portion 42 However, the rotor body 31 may be a separate member. Further, the inclination of the taper gap 45 with respect to the central axis J1 may be made larger than that shown in FIG. The bearing mechanisms 4 and 4a are not a so-called full fill structure in which the entire bearing gap is continuously filled with the lubricating oil 10, but a so-called partial fill structure in which the lubricating oil 10 is divided and filled inside the bearing. Also good.

  The protrusion 434 formed on the side portion 432 of the seal member 43 may be a recess or may be formed on the inner side surface 4321. Further, if the mark of the side portion 432 is provided in the vicinity of the position where the interface 11 is visually recognized, the mark may be formed by only one line at the position indicating the target filling amount. A scale indicating the position in the axial direction in units of 1 mm may be provided.

  In the interface measurement shown in FIG. 6, the position where the camera 62 images the interface 11 may be obliquely upward as long as it is approximately outside in the radial direction of the seal member 43a. The interface measurement is not limited to that performed by the camera 62. For example, a reflective optical sensor having a light projecting unit and a light receiving unit may be used, or may be performed by visual observation by an operator.

  The motor 1 is not limited to a shaft-fixed motor having a rotor portion fixed to the bearing portion and a stator portion fixed to the shaft portion. The rotor portion fixed to the shaft portion and the bearing portion are fixed. It may be a shaft rotation type motor having a stator portion. That is, in the motor 1, the shaft portion rotates with respect to the bearing portion so that the shaft portion is supported by the fluid dynamic pressure of the lubricating oil generated in the bearing gap between the inner surface of the bearing portion. What is necessary is just to be supported by a part. The motor 1 may be an inner rotor type.

  The recording disk drive device 5 is not limited to a hard disk drive device, and may be a device that drives an optical disk, a magneto-optical disk, etc. The motor 1 having the bearing mechanism 4 reads and writes information to and from the recording disk 51. It is suitable for one or both of them, that is, a recording disk drive device that performs reading or writing. The motor 1 may be used in other devices such as a laser printer.

It is a longitudinal cross-sectional view of a recording disk drive device. It is a longitudinal cross-sectional view of a motor. It is a longitudinal cross-sectional view of a sealing member. It is an enlarged view of the seal member vicinity. It is a figure which shows the flow of manufacture of a part of motor. It is a figure which shows an interface measuring apparatus. It is a figure which shows the example of the dispersion | variation in an interface position. It is a figure which shows the example of the dispersion | variation in an interface position. It is a figure which shows the other example of an interface measuring apparatus. It is a figure which shows the flow of manufacture of a part of motor. It is a figure which shows the other example of a bearing mechanism.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Motor 2 Stator part 3 Rotor part 4, 4a Bearing mechanism 5 Recording disk drive device 10 Lubricating oil 11 Interface 41 Shaft part 42 Bearing part 43a, 43b Seal member 44 Bearing gap 45 Taper gap 46 Thrust bearing gap 51 Recording disk 52 Access part 53 Housing 311 First Inclined Bearing Surface 431 Lid 434 Projection 4112 Outer Inclined Surface 4321 Inner Surface H1, H2 Interface Position J1 Central Axis S11-S18, S21-S25 Steps

Claims (10)

A fluid dynamic bearing mechanism used in an electric motor,
A bearing portion;
The bearing portion is inserted into the bearing portion and rotated relative to the bearing portion by utilizing the fluid dynamic pressure of the lubricating oil generated in the bearing gap between the inner surface of the bearing portion. A supported shaft portion;
An annular taper gap whose width gradually increases toward the opening side is formed around the shaft portion, and the lubricating oil leakage is formed by forming an interface of the lubricating oil continuous from the bearing gap in the taper gap. A sealing member for preventing
With
The inner diameter of each side surface of the taper gap gradually decreases toward the opening side,
The fluid dynamic pressure bearing mechanism, wherein the seal member is made of a translucent material that makes the interface of the lubricating oil visible from the outside in the radial direction. The fluid dynamic bearing mechanism according to claim 1,
The fluid dynamic pressure bearing mechanism, wherein the seal member has a mark near a position where the interface is visually recognized. The fluid dynamic bearing mechanism according to claim 1 or 2,
The fluid dynamic pressure bearing mechanism, wherein the lubricating oil is colored. The fluid dynamic bearing mechanism according to claim 1 or 2,
The fluid dynamic pressure bearing mechanism, wherein the lubricating oil contains a fluorescent agent. The fluid dynamic bearing mechanism according to any one of claims 1 to 4,
The fluid dynamic pressure bearing mechanism, wherein the seal member has an annular lid portion that covers the opening of the taper gap. An electric motor,
A fluid dynamic bearing mechanism according to any one of claims 1 to 5,
A stator portion to which one of the bearing portion and the shaft portion is fixed;
A rotor portion fixed to the other of the bearing portion and the shaft portion;
A motor comprising: A recording disk drive device comprising:
The motor according to claim 6, wherein the motor rotates a recording disk;
An access unit for reading or writing information on the recording disk;
A housing for housing the motor and the access unit;
A recording disk drive device comprising: A method for manufacturing a fluid dynamic bearing mechanism used in an electric motor,
a) inserting the shaft portion into the bearing portion;
b) An annular gap whose width gradually increases toward the opening side around the shaft portion by inserting the shaft portion into an annular sealing member having translucency, and the inner diameters of both side surfaces are Forming a taper gap that gradually decreases toward the opening;
c) filling the bearing gap between the inner surface of the bearing section and the shaft section with lubricating oil, and forming an interface of the lubricating oil continuous from the bearing gap in the tapered gap;
d) confirming the position of the interface in the axial direction from the radially outer side of the seal member;
A method for producing a fluid dynamic bearing mechanism, comprising: A method for manufacturing a fluid dynamic bearing mechanism according to claim 8,
In the step d), the position of the interface of the lubricating oil is confirmed at three or more positions in the circumferential direction of the outer surface of the seal member. A method for manufacturing a fluid dynamic bearing mechanism according to claim 8 or 9,
e) reducing the pressure around the fluid dynamic bearing mechanism;
f) confirming the position of the interface in the axial direction from the radially outer side of the seal member;
A method for manufacturing a fluid dynamic bearing mechanism, further comprising:

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