JP2004132521A - Dynamic pressure bearing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suitably prevent external leakage of a lubricating fluid while excellently circulating and moving the lubricating fluid with a simple constitution. <P>SOLUTION: This dynamic pressure beating device is provided with a fluid circulating guiding member 139 opposed at a proper distance in the shaft direction to a shaft directional end surface 133b of a fluid dynamic pressure bearing 133, and prevents external splashing of the lubricating fluid by receiving the lubricating fluid trying to splash outside from the opening side of a bearing holder 132 by insertion of a rotary shaft 136 by the fluid circulating guiding member 139, and secures the smooth circulation-movement by circulating and moving the lubricating fluid by defining a fluid circulating space FS for allowing the circulation-movement of the lubricating fluid between the fluid circulating guiding member 139 and the shaft directional end surface 133b of the fluid dynamic pressure bearing 133. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a dynamic pressure bearing device configured to inject a lubricating fluid into a bearing holder formed of a bag-shaped hollow member holding a fluid dynamic pressure bearing and to fill the lubricating fluid up to the bearing surface of the fluid dynamic pressure bearing.
[0002]
[Prior art]
2. Description of the Related Art In recent years, a dynamic pressure bearing device using the dynamic pressure of a lubricating fluid has been employed in motors and the like used in various rotary drive devices. For example, in a spindle motor for driving a CD-ROM shown in FIG. 7, a substantially cylindrical bag whose one end in the axial direction is open and the other end is closed is provided in a mounting hole 1 a formed through the fixed frame 1. A bearing holder 2 made of a hollow member is fixed, and a bearing sleeve 3 as a fluid dynamic pressure bearing is held in a hollow inside of the bearing holder 2 in a state of being inserted in an axial direction.
[0003]
A bearing surface for generating dynamic pressure is formed on the inner peripheral surface of the bearing sleeve 3, and the rotating shaft 4 is rotatably inserted along the dynamic pressure surface. An appropriate lubricating fluid such as oil is injected into the hollow inside of the bag. The lubricating fluid in the bearing holder 2 is filled at least to such an extent that the bearing surface of the bearing sleeve 3 is filled. On the other hand, a dynamic pressure generating means including a herringbone-shaped groove is formed on the bearing surface of the bearing sleeve 3, and a dynamic pressure is generated in the lubricating fluid by the pumping action of the dynamic pressure generating means. The rotary shaft 4 is supported in a non-contact manner by the dynamic pressure obtained by the above.
[0004]
By the way, in such a dynamic pressure bearing device, there is conventionally known a structure in which a lubricating fluid is appropriately circulated and moved by a dynamic pressure so as to achieve good bearing characteristics and a long life of the lubricating fluid. I have. Specifically, the fluid circulation guide groove 5 is formed in the outer peripheral wall surface of the bearing sleeve 3 so as to be recessed so as to extend in the axial direction. The discharged lubricating fluid is circulated in the axial direction through the fluid circulation guide groove 5, whereby the lubricating fluid sent to the axial end face 3 a of the bearing sleeve 3 flows again into the bearing inside of the bearing sleeve 3. I try to make it. In some cases, the above-described fluid circulation guide groove 5 is formed on the inner peripheral wall surface side of the bearing holder 2.
[0005]
[Problems to be solved by the invention]
However, in the dynamic pressure bearing device configured to store the lubricating fluid in the bearing holder 2 made of such a bag-shaped hollow member, the lubricating fluid is injected into the bearing holder 2 and then the rotating shaft 4 is moved into the bearing sleeve 3. When the rotary shaft 4 is inserted, the air existing in the bearing sleeve 3 before the rotary shaft 4 is inserted is pushed in the same direction by the insertion of the rotary shaft 4, It may be pushed out of the bearing sleeve 3. The air extruded from the bearing sleeve 3 becomes bubbles in the lubricating fluid stored in the bearing holder 2, and pushes up the lubricating fluid toward the opening side of the bearing holder 2. Lubricating fluid may be scattered outward through the gap with the sleeve 3, the above-described fluid circulation guide groove 5, or the bearing gap.
[0006]
Further, even after the rotary shaft 4 is inserted, the air remaining in the lubricating fluid expands due to the heat generated by the rotation drive, and the expanded air causes the lubricating fluid in the bearing holder 2 to move outward. It may be scattered. The lubricating fluid scattered outside in this manner once adheres to the rotating member such as the rotating shaft 4, but is further scattered radially outward by centrifugal force during rotation, and as a result, the motor In some cases, a fatal problem may occur by contaminating the drive system and the rotating side member.
[0007]
Further, since the lubricating fluid once scattered outside the bearing holder 2 does not return to the inside of the bearing portion of the bearing sleeve 3, the amount of the lubricating fluid tends to be insufficient at an early stage, and the bearing life is shortened. It can also be converted. In order to prevent the lubricating fluid from scattering to the outside, measures to reduce the amount of lubricating fluid injected are conceivable, but in this case, the bearing life is shortened originally and sufficient dynamic Pressure may not be obtained.
[0008]
Heretofore, for example, a device in which a seal plate is disposed so as to protrude at an outer end portion of a bearing member, such as a dynamic pressure bearing device described in JP-A-2000-337383, has been proposed. In the prior art, the seal plate is arranged so as to contact the axial end surface of the bearing member. In other words, when a seal plate having such a structure is provided, the smooth circulation movement of the lubricating fluid is hindered, and a large amount of air is entrained in the flow of the circulation movement of the lubricating fluid, so that bubbles are easily generated. However, there are problems such as deterioration of bearing characteristics and promotion of external leakage of lubricating fluid. Further, depending on the attitude of the entire apparatus, external leakage of the lubricating fluid may occur.
[0009]
Accordingly, an object of the present invention is to provide a dynamic pressure bearing device capable of appropriately preventing the external leakage of a lubricating fluid while favorably circulating the lubricating fluid with a simple configuration.
[0010]
[Means for Solving the Problems]
In order to achieve the above object, in the hydrodynamic bearing device according to claim 1 of the present invention, the lubricating fluid is circulated on the outer peripheral wall surface of the fluid dynamic pressure bearing from the outer peripheral wall surface of the fluid dynamic pressure bearing toward the axial end surface. In the hydrodynamic bearing device in which the fluid circulation guide groove to be formed is formed, a fluid circulation guide member facing the axial end surface of the fluid dynamic pressure bearing at an appropriate distance in the axial direction is provided, and the fluid circulation guide is provided. A fluid circulation space that allows the lubricating fluid to circulate is defined between the member and the axial end face of the fluid dynamic bearing.
According to the hydrodynamic bearing device having such a configuration, even if the lubricating fluid attempts to scatter outside from the opening side of the bearing holder due to insertion of the rotating shaft or the like, the lubricating fluid is applied to the hydrodynamic bearing. By being received by the fluid circulation guide member arranged so as to face the outside, external scattering is prevented.
On the other hand, the lubricating fluid circulating from the fluid circulation guide groove of the fluid dynamic pressure bearing through the axial end face flows into the fluid circulation space between the axial end face of the fluid dynamic pressure bearing and the fluid circulation guide member. It flows well inside, and smooth circulation is ensured.
[0011]
In the hydrodynamic bearing device according to a second aspect of the present invention, the innermost peripheral portion of the fluid circulation guide member in the first aspect has a radius greater than the outer peripheral wall surface of the fluid dynamic pressure bearing and the groove bottom surface of the fluid circulation guide groove. It is arranged inside the direction.
According to the hydrodynamic bearing device according to claim 2 having such a configuration, since the fluid circulation guide member completely covers the opening of the gap between the bearing holder and the fluid dynamic pressure bearing, the external scatter from there. The lubricating fluid to be intended is reliably received by the fluid circulation guide member.
[0012]
Further, in the dynamic pressure bearing device according to claim 3 of the present invention, the outermost peripheral portion of the fluid circulation guide member according to claim 1 is inserted along the inner peripheral wall surface defining the opening of the bearing holder. It is fixed by that.
According to the hydrodynamic bearing device according to claim 3 having such a configuration, the fluid circulation guide member is not provided with a portion that protrudes outward in the radial direction of the bearing holder. By disposing the member only on the radially inner side of the bearing holder, the generation of the lubricating fluid that leaks outward through the fluid circulation guide member can be effectively prevented.
[0013]
Furthermore, in the hydrodynamic bearing device according to claim 4 of the present invention, the inner peripheral wall surface defining the opening of the bearing holder to which the fluid circulation guide member according to claim 1 is fixed is a fluid dynamic bearing. Has an inner diameter that is larger than the inner diameter of the inner peripheral wall surface that holds.
According to the dynamic pressure bearing device according to claim 4 having such a configuration, the size of the fluid circulation space is also increased by an amount corresponding to the enlargement of the opening of the bearing holder. Even so, a sufficient amount of lubricating fluid can be circulated.
[0014]
Further, in the dynamic bearing device according to claim 5 of the present invention, the innermost peripheral portion of the fluid circulation guide member according to claim 1 is arranged in a radial direction with respect to the rotating shaft or a rotating member integrally rotating with the rotating shaft. And the opposing gap formed between the innermost peripheral portion of the fluid circulation guide member and the rotation side member is set to a size that does not generate capillary force with respect to the lubricating fluid.
According to the hydrodynamic bearing device having such a configuration, the lubricating fluid that is scattered outside from the bearing portion of the fluid dynamic pressure bearing leaks through the gap between the fluid circulation guide member and the rotation side member. Will not be done.
[0015]
Further, in the fluid dynamic bearing device according to claim 6 of the present invention, the fluid circulation space in claim 1 is larger than 1/4 of the volume occupied by the insertion portion of the rotary shaft in the hollow internal space of the fluid dynamic pressure bearing. It is formed to have a large volume.
According to the dynamic pressure bearing device according to the sixth aspect having such a configuration, when the rotary shaft is inserted into the dynamic pressure bearing portion, the entire amount of the lubricating fluid that tends to leak to the outside is reliably stored in the fluid circulation space. It is actually confirmed that the lubricating fluid is scattered to the outside.
[0016]
Furthermore, in the dynamic pressure bearing device according to claim 7 of the present invention, the fluid circulation guide member according to claim 1 attracts the rotating shaft and the rotating member integrally rotating with the rotating shaft in the axial direction by magnetic action. It is also used by a suction magnet.
According to the hydrodynamic bearing device having such a configuration, an increase in the number of components is prevented, and cost reduction is achieved.
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
First, the overall structure of a drive unit for a CD-ROM or DVD equipped with a motor to which the present invention is applied will be described. A mechanical chassis 11 of the CD-ROM drive unit 10 shown in FIG. An optical pickup device 14 for writing or reading information by irradiating the spindle motor unit 13 and the recording disk 12 with laser light is mounted.
[0018]
The recording disk 12 is mounted on a rotating disk table (refer to a symbol T in FIG. 2) mounted on a rotating shaft of the spindle motor unit 13, while the optical pickup device 14 is mounted on the mechanical chassis 11. It is mounted so as to be able to reciprocate with respect to the pair of parallel guide shafts 15 attached thereto, and irradiates the recording disk 12 with a light beam emitted from a laser light source (not shown) through an objective lens 16. It has a configuration for detecting reflected light from the recording disk 12.
[0019]
As shown in FIG. 2, a hollow cylindrical bearing holder 132 is attached to the main body frame 131 so as to stand substantially vertically. A bearing sleeve 133 as a fluid bearing member is joined to the hollow inner side of the bearing holder 132 from an opening on the upper end side of the bearing holder 132 in the drawing by fixing means such as press fitting or shrink fitting. The bearing sleeve 133 is formed of a copper-based material such as phosphor bronze to facilitate processing, and has a center hole formed so as to penetrate in the axial direction.
[0020]
The annular base of the stator core 134 is fixed to the outer peripheral wall surface of the bearing holder 132 by being inserted therethrough. A drive coil 135 is wound around each of the plurality of salient pole portions provided on the stator core 134, and teeth portions provided to protrude in the circumferential direction at the protruding tip portions of the salient pole portions. They are arranged in rows in the direction.
[0021]
On the other hand, a step portion 132a is provided in the opening at the lower end in the figure of the bearing holder 132 so as to increase the inner diameter downward in the figure, and a disc-shaped bearing support is provided for the step portion 132a. The plate 132b is attached so as to be in close contact. The opening at the lower end in the figure of the bearing holder 132 is hermetically closed by the bearing support plate 132b, whereby the hollow inner space of the bearing holder 132 is formed to form a bag-like space. Have been. An appropriate amount of a lubricating fluid such as a lubricating oil is injected into the bag-shaped space of the bearing holder 132.
[0022]
Further, a rotating shaft 136 that forms a part of the rotor set is rotatably inserted into the center hole of the bearing sleeve 133 described above. The rotating shaft 136 in this embodiment is formed of stainless steel, and a dynamic pressure bearing surface is formed on the outer peripheral wall surface of the rotating shaft 136 and the inner peripheral surface of the bearing sleeve 133, respectively. The dynamic pressure bearing surface on the rotating shaft 136 side and the dynamic pressure bearing surface on the bearing sleeve 133 side are disposed so as to face each other with a small gap in the radial direction, and a pair of radial dynamic The pressure bearing portions RB, RB are configured. More specifically, the dynamic pressure bearing surface on the bearing sleeve 133 side and the dynamic pressure bearing surface on the rotary shaft 136 side in the radial dynamic pressure bearing portion RB are arranged to face each other via a radial gap of several μm. The lubricating fluid injected into the bearing holder 132 described above is filled in the bearing space formed by the radial gap so as to completely fill the dynamic pressure bearing surface.
[0023]
Further, on at least one side of both the dynamic pressure bearing surfaces of the bearing sleeve 133 and the rotating shaft 136, for example, a herringbone-shaped radial dynamic pressure generating groove (not shown) is divided into two blocks in the axial direction so as to be concave. The lubricating fluid is pressurized by the pumping action of the radial dynamic pressure generating groove when the rotating shaft 136 is rotated to generate a dynamic pressure, and the rotating shaft 136 and A rotating disk table T (described later) fixed to the rotating shaft 136 is rotatably supported.
[0024]
On the other hand, a plurality of fluid circulation guide grooves 133a extending in the axial direction are formed in the outer peripheral wall surface of the bearing sleeve 133 described above. The fluid circulation guide groove 133a is for circulating the lubricating fluid, and the lubricating fluid discharged from the inside of the bearing of the bearing sleeve 133 to the outside of the bearing passes through the fluid circulation guide groove 133a. The bearing sleeve 133 is circulated in the axial direction, further circulates radially inward on the axial end surface 133b of the bearing sleeve 133, and flows again into the bearing from the axial end surface 133b. ing.
[0025]
A thrust bearing plate 132c is mounted on the inner side (upper side in the figure) of the bearing support plate 132b, and a lower end of the rotating shaft 136 is provided on the upper side in the figure of the thrust bearing plate 132c. A pivot portion 136a formed on the side portion so as to form a part of a sphere is arranged so as to substantially contact the point, thereby forming a thrust bearing portion SB.
[0026]
On the other hand, a central boss 137a of a substantially cup-shaped rotor case 137 formed in a substantially hollow cylindrical shape is provided at a portion where the rotating shaft 136 protrudes upward in the drawing from the bearing holder 132 with respect to the rotating shaft 136. It is fixed by press fitting. A cylindrical rotor magnet 137c, which is magnetized alternately by NS at regular intervals in the circumferential direction, is fixed to an inner peripheral surface side of an annular peripheral wall portion 137b provided on an outer peripheral portion of the rotor case 137. . The inner peripheral surface of the rotor magnet 137c is disposed so as to approach each salient pole of the stator core 134 from the radially outer side.
[0027]
An attraction magnet 138 is externally fitted to the upper end portion of the outer peripheral side wall surface of the bearing holder 132 in the figure. The attraction magnet 138 is arranged so as to be close to the inner surface on the lower surface side of the rotor case 137 in the drawing, and attracts the rotor case 137 in the axial direction by the magnetic action of the attraction magnet 138 so that the above-described rotor is formed. The entire set is pulled in the axial direction so that the rotor set does not fall off in the axial direction.
[0028]
Further, a rotating disk table (turntable) T formed of a substantially disc-shaped resin material (PC) is attached to a protruding portion of the rotating shaft 136 on the upper side in the figure. The rotary disk table T is fixed by press-fitting a rotary shaft press-fitting hole formed in a central portion to the rotary shaft 136, and has a substantially conical shape formed in a convex shape from the fixed portion toward the upper side in the figure. The recording disk (see reference numeral 12 in FIG. 1) mounted on the disk table T is held in a state where it is positioned at a predetermined position by the positioning protrusions Ta. A yoke plate Tb for attaching a chucking magnet is arranged on the top of the positioning projection Ta.
[0029]
Here, the inner peripheral wall surface 132d that defines the opening at the upper end in the drawing of the bearing holder 132 described above has an inner diameter larger than that of the inner peripheral wall surface 132e where the bearing sleeve 133 is inserted. Further, the outer peripheral side substrate 139a of the fluid circulation guide member 139 is fixed by being inserted into the inner peripheral wall surface 132d having an opening having an enlarged inner diameter by press fitting or the like.
[0030]
That is, the fluid circulation guide member 139 is formed of a ring-shaped member having a substantially L-shaped cross section, and the main partition plate 139b protruding from the outer peripheral substrate 139a radially inward toward the eaves. have. The main partition plate 139b is disposed so as to face the axial end surface 133b on the upper end side of the bearing sleeve 133 in the drawing, and is appropriately arranged in the axial direction (upward in the drawing) from the axial end surface 133b of the bearing sleeve 133. Are arranged at a distance of. That is, a fluid circulation space FS for permitting the circulation movement of the lubricating fluid is defined between the main partition plate 139b of the fluid circulation guide member 139 and the axial end surface 133b of the bearing sleeve 133. .
[0031]
In the present embodiment, the distance between the main partition plate 139b of the fluid circulation guide member 139 and the axial end surface 133b of the bearing sleeve 133 is set to be 0.5 mm or more, and between them. The total volume of the defined fluid circulation space FS is formed so as to have a volume larger than １ ／ of the volume occupied by the insertion portion of the rotary shaft 136 in the hollow inner space of the bearing sleeve 133 described above. Have been.
[0032]
In addition, the innermost peripheral edge 139c of the main partition plate 139b of the fluid circulation guide member 139 is closer to the center in the radial direction than the outer peripheral wall surface of the bearing sleeve 133 and the bottom surface of the fluid circulation guide groove 133a. (Inward), for example, 1.5 mm or more, and the innermost peripheral edge 139c of the fluid circulation guide member 139 is the outer peripheral wall surface of the central boss portion 137a of the rotor case 137 described above. Are arranged so as to face each other in the radial direction. The facing gap between the innermost peripheral edge 139c of the main partition plate 139b of the fluid circulation guide member 139 and the outer peripheral wall surface of the center boss 137a of the rotor case 137 is a capillary tube for the lubricating fluid. The gap size is set so as not to generate a suction force due to a force, for example, a gap size of 0.5 mm or more.
[0033]
According to the present embodiment having such a configuration, even if the lubricating fluid tries to scatter outside from the opening side of the bearing holder 132 by inserting the rotating shaft 136 into the bearing sleeve 133, the lubricating fluid is applied to the bearing sleeve 133. The lubricating fluid is received by the fluid circulation guide member 139 disposed so as to face the axial end surface 133b of the sleeve 133, so that the lubricating fluid is prevented from scattering outside. Specifically, when the rotating shaft 136 is inserted into the bearing sleeve 133, the lubricating fluid can be replenished to the maximum amount in which the inner and outer peripheral wall surfaces of the bearing sleeve 133 are completely filled with the lubricating fluid. In any case, the external leakage of the lubricating fluid is prevented regardless of the attitude of the hydrodynamic bearing device.
[0034]
On the other hand, the lubricating fluid that is going to circulate through the axial end surface 133b of the bearing sleeve 133 satisfactorily in the fluid circulation space FS between the axial end surface 133b of the bearing sleeve 133 and the fluid circulation guide member 139. It flows and smooth circulation is maintained.
[0035]
In the present embodiment, the innermost peripheral edge 139c of the fluid circulation guide member 139 is disposed so as to protrude radially inward from the outer peripheral wall surface of the bearing sleeve 133 and the bottom surface of the fluid circulation guide groove 133a. Since the fluid circulation guide member 139 completely covers the opening of the gap between the bearing holder 132 and the bearing sleeve 133, the fluid circulation guide member 139 surely receives the lubricating fluid scattered outside from the fluid circulation guide member 139. It has become.
[0036]
Further, in this embodiment, since the fluid circulation guide member 139 is attached so as to be inserted along the inner peripheral wall surface of the opening of the bearing holder 132, the fluid circulation guide member 139 has the bearing holder 132 No radially outwardly extending portion is provided. Therefore, the fluid circulation guide member 139 is disposed only on the radially inner side of the bearing holder 132, so that the fluid circulation guide member 139 is transmitted. Therefore, the generation of the lubricating fluid that leaks outward is prevented well.
[0037]
Further, in the present embodiment, the inner peripheral wall surface 132d of the opening of the bearing holder 132 to which the fluid circulation guide member 139 is attached is larger in inner diameter than the inner peripheral wall surface 132e through which the bearing sleeve 133 is inserted. As a result, the size of the fluid circulation space FS is increased by the extent that the opening of the bearing holder 132 is enlarged, so that a sufficient amount of lubricating fluid can be circulated even in a miniaturized device. Is possible.
[0038]
Further, in the present embodiment, the innermost peripheral edge 139c of the fluid circulation guide member 139 is disposed so as to face the outer peripheral wall surface of the center boss portion 137a of the rotor case 137 that rotates integrally with the rotating shaft 136. Since the opposing gap between the innermost peripheral edge 139c of the guide member 139 and the center boss 137a of the rotor case 137 is set to a gap dimension that does not generate a suction force by a capillary force with respect to the lubricating fluid. In addition, the lubricating fluid that tends to scatter outside from the bearing portion side of the bearing sleeve 133 does not leak outside through the gap between the fluid circulation guide member 139 and the center boss portion 137a of the rotor case 137.
[0039]
Further, in this embodiment, the volume of the fluid circulation space FS is formed so as to have a volume larger than １ ／ of the volume occupied by the insertion portion of the rotating shaft 136 in the hollow internal space of the bearing sleeve 133. It has been actually confirmed that the entire amount of the lubricating fluid that leaks out when the rotating shaft 136 is inserted into the bearing sleeve 133 is reliably stored in the fluid circulation space SF. Is reliably prevented.
[0040]
On the other hand, in the embodiment according to FIG. 3 in which members corresponding to the above-described embodiment are represented by the same reference numerals, the suction magnet 149 having the same function as the above-described embodiment causes the function of the fluid circulation guide member 139 to be shared. ing. The attraction magnet 149 is attached so as to penetrate along the inner peripheral wall surface of the enlarged opening provided at the upper end in the drawing of the bearing holder 132, and the attraction magnet 149 and the upper end of the bearing sleeve 133 in the drawing are shown. A fluid circulation space FS that allows circulation of the lubricating fluid by being separated from the axial end face 133b by an appropriate distance in the axial direction is defined.
[0041]
The innermost peripheral edge 149a of the attraction magnet 149 is disposed so as to protrude radially toward the center from the outer peripheral wall surface of the bearing sleeve 133 and the bottom surface of the fluid circulation guide groove 133a. Further, the innermost peripheral edge 149a of the attraction magnet 149 is disposed so as to radially oppose the outer peripheral wall surface of the center boss 137a of the rotor case 137, and the center boss 137a of the rotor case 137 is provided. Is formed so as to form a gap with respect to the outer peripheral wall of the lubricating fluid so as not to generate a capillary force to the lubricating fluid.
[0042]
According to the second embodiment, in addition to the operation and effect according to the first embodiment, the number of components is reduced, and the cost is reduced. .
[0043]
In the second embodiment, if the surface of the attraction magnet 149 is coated with a paint that does not absorb a lubricating fluid such as an epoxy resin, the lubricating fluid does not seep into the attraction magnet 149. And at the same time, it is possible to prevent the attraction magnet 149 from cracking. For example, even when the rotation shaft 136 comes into contact with the attraction magnet 149 when the rotation shaft 136 is inserted, fragments of the magnet may be removed. Mixing into the lubricating fluid can be prevented.
[0044]
Further, if an oil-repellent material is applied from above the coating layer of the paint to the attraction magnet 149, the lubricating fluid is prevented from leaking to the outside through the surface of the attraction magnet 149.
[0045]
Also, as in the embodiment shown in FIG. 4, the inner peripheral wall surface of the bearing holder 132 is enlarged radially outward between the fluid circulation guide member 139 (149) and the bearing sleeve 133. If this is done, the space in which the lubricating fluid can be stored is expanded, and the fluid circulation guide member 139 can be made closer to the axial end face 133b of the bearing sleeve 133, thereby reducing the height of the hydrodynamic bearing device. It becomes possible to reduce.
[0046]
Further, in the embodiment shown in FIG. 5, a flange portion 132f projecting inward in the radial direction is provided at an opening formed at the upper end in the drawing of the bearing holder 132, and the flange portion 132f is provided. Thus, the above-described fluid circulation guide member is also used. Also in this case, an effect that an increase in the number of parts can be prevented can be obtained.
[0047]
Furthermore, in the embodiment shown in FIG. 6, a suction magnet 138 that attracts the entire rotor set including the rotor case 137 in the axial direction is attached to the center side portion of the rotor case 137, and the suction magnet 138 is provided. A magnetic plate 138a is attached to the upper end surface of the bearing holder 132 in the figure so as to face the 138 in the axial direction, and the magnetic plate 138a also serves as the fluid circulation guide member. Also in this case, an effect of preventing an increase in the number of parts can be obtained.
[0048]
As mentioned above, although the embodiment of the invention made by the inventor has been specifically described, the present invention is not limited to the above embodiment, and it can be said that various modifications can be made without departing from the gist thereof. Not even.
[0049]
For example, in each of the embodiments described above, the fluid circulation guide groove is provided on the bearing sleeve (fluid dynamic pressure bearing) side, but the present invention is similarly applied to a device provided on the bearing holder side. be able to.
[0050]
Further, the present invention can be similarly applied to a dynamic pressure bearing device of various rotary drive devices used other than the CD-ROM drive unit as in the above-described embodiments.
[0051]
【The invention's effect】
As described above, the hydrodynamic bearing device according to the first aspect of the present invention is provided with a fluid circulation guide member facing the axial end surface of the fluid dynamic bearing at an appropriate distance in the axial direction. By receiving the lubricating fluid, which tends to scatter outside from the opening side of the bearing holder by the insertion of the lubricating fluid, by the fluid circulation guide member, the lubrication fluid is prevented from being scattered outside, and the fluid circulation guide member and the shaft of the fluid dynamic pressure bearing are prevented. By defining a fluid circulation space that allows the lubricating fluid to circulate and move between the lubricating fluid and the axial end face, the lubricating fluid circulates from the outer peripheral wall surface of the fluid dynamic pressure bearing toward the axial end face to achieve smooth circulation movement. Since the lubricating fluid is circulated and moved satisfactorily, it is possible to prevent external leakage of the lubricating fluid with a simple structure, thereby improving the reliability of the hydrodynamic bearing device. It can be.
[0052]
Further, in the hydrodynamic bearing device according to a second aspect of the present invention, the innermost peripheral portion of the fluid circulation guide member in the first aspect is radiused from the outer peripheral wall surface of the fluid dynamic pressure bearing and the groove bottom surface of the fluid circulation guide groove. The fluid circulation guide member completely covers the opening of the gap between the bearing holder and the fluid dynamic pressure bearing, and the fluid circulation guide member surely receives the lubricating fluid to be scattered outside from there. With this configuration, the above-described effects can be reliably obtained.
[0053]
Further, in the dynamic pressure bearing device according to claim 3 of the present invention, the outermost peripheral portion of the fluid circulation guide member according to claim 1 is inserted along the inner peripheral wall surface that defines the opening of the bearing holder. This prevents the generation of the lubricating fluid that leaks through the fluid circulation guide member by not fixing the portion that protrudes radially outward of the bearing holder to the fluid circulation guide member. Thus, the above-described effects can be further enhanced.
[0054]
Still further, according to a fourth aspect of the present invention, there is provided a hydrodynamic bearing device, wherein the inner peripheral wall defining the opening of the bearing holder to which the fluid circulation guide member is fixed is provided with a fluid dynamic pressure bearing. As the inner diameter is larger than the inner diameter of the inner peripheral wall that is held, the size of the fluid circulation space is enlarged by the size of the opening of the bearing holder, and a sufficient amount of lubrication Therefore, it is possible to reliably obtain the above-described effects while reducing the size of the hydrodynamic bearing device.
[0055]
According to a fifth aspect of the present invention, in the fluid dynamic bearing device, the innermost peripheral portion of the fluid circulation guide member according to the first aspect is arranged in a radial direction with respect to the rotating shaft or a rotating member integrally rotating with the rotating shaft. And the opposed gap formed between the innermost peripheral portion of the fluid circulation guide member and the rotation side member is set to a dimension that does not generate capillary force, so that the bearing portion of the fluid dynamic pressure bearing is This prevents the lubricating fluid from splattering from the outside from leaking outside, so that the above-described effects can be more reliably obtained.
[0056]
Further, in the dynamic pressure bearing device according to claim 6 of the present invention, the fluid circulating space in claim 1 is set to be smaller than 1/4 of the volume occupied by the insertion portion of the rotating shaft in the hollow internal space of the fluid dynamic pressure bearing. Formed to have a large volume, ensure that the entire amount of lubricating fluid that leaks out when the rotating shaft is inserted into the dynamic pressure bearing part is reliably stored in the fluid circulation space, and the lubricating fluid scatters outside. Is surely prevented, so that the above-described effects can be more reliably obtained.
[0057]
According to a seventh aspect of the present invention, in the fluid dynamic bearing device, the fluid circulation guide member according to the first aspect is axially attracted to the rotating shaft and the rotating member integrally rotating with the rotating shaft by magnetic action. Since the suction magnet is also used to prevent an increase in the number of parts and reduce the cost, the above-described effects can be obtained with an inexpensive device.
[Brief description of the drawings]
FIG. 1 is an external perspective explanatory view showing a CD-ROM or DVD drive unit as an example of a device to which the present invention is applied.
FIG. 2 is an explanatory longitudinal sectional view showing an embodiment of a motor including a dynamic pressure bearing device employed in the CD-ROM or DVD drive unit shown in FIG.
FIG. 3 is an explanatory longitudinal sectional view showing a structure of a motor including a hydrodynamic bearing device according to another embodiment of the present invention.
FIG. 4 is a schematic longitudinal sectional view showing a schematic structure of a dynamic pressure bearing device according to still another embodiment of the present invention.
FIG. 5 is a schematic longitudinal sectional view illustrating a schematic structure of a dynamic pressure bearing device according to still another embodiment of the present invention.
FIG. 6 is a schematic longitudinal sectional view showing a schematic structure of a hydrodynamic bearing device according to still another embodiment of the present invention.
FIG. 7 is an explanatory longitudinal sectional view showing an example of a structure of a motor provided with a hydrodynamic bearing device having a conventional structure.
[Explanation of symbols]
10 CD-ROM drive unit
13 Recording disk
13 Spindle motor section
T rotating disk table
131 Body frame
132 Bearing holder
132b Bearing support plate
132d, 132e inner wall surface
RB Radial dynamic pressure bearing
SB thrust bearing
133 Bearing sleeve (fluid bearing member)
133a Fluid circulation guide groove
133b axial end face
134 Stator core
135 drive coil
136 rotation axis
137 Rotor case
137a Center boss
137b annular peripheral wall
137c rotor magnet
138,149 Suction magnet
139 Fluid circulation guide member
139a Outer side substrate
139b Main partition
FS fluid circulation space

Claims (7)

A bearing holder made of a substantially cylindrical bag-shaped hollow member having one end opened in the axial direction and the other end closed, a fluid dynamic pressure bearing held inside the hollow of the bearing holder, and a fluid dynamic pressure bearing. A rotating shaft rotatably inserted along a bearing surface formed on the peripheral surface,
Lubricating fluid injected into the hollow interior of the bearing holder is filled so as to at least fill the bearing surface of the fluid dynamic bearing,
The fluid dynamic pressure bearing is configured to support the rotating shaft in a non-contact manner by generating dynamic pressure in the lubricating fluid by dynamic pressure generating means provided on a bearing surface of the bearing,
The lubricating fluid circulates from the outer peripheral wall surface of the fluid dynamic pressure bearing or the inner peripheral wall surface of the bearing holder to the outer peripheral wall surface of the fluid dynamic pressure bearing or the inner peripheral wall surface of the bearing holder toward the axial end surface of the fluid dynamic pressure bearing. In the hydrodynamic bearing device in which the fluid circulation guide groove to be formed is formed,
A fluid circulation guide member facing the axial end surface of the fluid dynamic pressure bearing at an appropriate distance in the axial direction is provided,
A hydrodynamic bearing device, wherein a fluid circulating space that allows the lubricating fluid to circulate is defined between the fluid circulation guide member and an axial end face of the fluid dynamic pressure bearing. 2. The fluid dynamic guide according to claim 1, wherein an innermost peripheral portion of the fluid circulation guide member is disposed radially inward from an outer peripheral wall surface of the fluid dynamic pressure bearing and a bottom surface of the fluid circulation guide groove. 3. Pressure bearing device. 2. The dynamic pressure according to claim 1, wherein the outermost peripheral portion of the fluid circulation guide member is fixed by being inserted along an inner peripheral wall surface defining an opening of the bearing holder. Bearing device. The inner peripheral wall surface that defines the opening of the bearing holder to which the fluid circulation guide member is fixed has an inner diameter that is larger than the inner diameter of the inner peripheral wall surface that holds the fluid dynamic pressure bearing. The hydrodynamic bearing device according to claim 2, wherein: The innermost peripheral portion of the fluid circulation guide member is disposed so as to radially oppose the rotating shaft or a rotating member that rotates integrally with the rotating shaft,
The opposed gap formed between the innermost peripheral portion of the fluid circulation guide member and the rotation side member is set to a size that does not generate a capillary force with respect to the lubricating fluid. The dynamic pressure bearing device according to the above. The fluid circulation space is formed to have a volume larger than 1/4 of the volume occupied by the insertion portion of the rotary shaft in the hollow internal space of the fluid dynamic pressure bearing. The dynamic pressure bearing device according to the above. 2. The dynamic pressure bearing according to claim 1, wherein the fluid circulation guide member is also used as an attraction magnet that attracts the rotating shaft and a rotating member integrally rotating with the rotating shaft in an axial direction by magnetic action. apparatus.

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