JP2007263311A - Dynamic pressure bearing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a bearing device which can maintain excellent bearing performance for a long period of time, efficiently and at low cost. <P>SOLUTION: The inner peripheral face 80a of a bearing member 8 is formed of a non-complete round face R which is circumferentially displaced and formed in a given shape in an axial direction. Therefore, after the bearing member 8 is formed by die molding and when an inner mold is demolded from the inner periphery of the bearing member 8, no interference between the inner peripheral face 80a of the bearing member 8 with the inner die occurs to avoid damage to the inner peripheral face 80a of the bearing member 8. Out of the non-complete round face R, areas R1 close to the outer peripheral face 2a of a shaft member 2 are formed of resin parts 82, so that dynamic pressure is prevented from being released in the parts where the pressure of lubricating oil is maximized in rotating the shaft member 2, and thereby efficient dynamic pressure action is acquired. Out of the non-complete round face R, a part other than the resin parts 82 is formed of porous part 81, so that the oil can be sequentially supplied into a radial bearing clearance, and thereby lubricity is improved. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a hydrodynamic bearing device that supports a shaft member in a non-contact manner by a hydrodynamic action of a fluid (lubricating fluid) generated in a bearing gap. This bearing device is a spindle of information equipment such as magnetic disk devices such as HDD and FDD, optical disk devices such as CD-ROM, CD-R / RW and DVD-ROM / RAM, and magneto-optical disk devices such as MD and MO. It is suitable for a small motor such as a motor, a polygon scanner motor of a laser beam printer (LBP), or a fan motor used for a cooling fan of an electric device.

For example, the hydrodynamic bearing device disclosed in Patent Document 1 includes a bearing member formed of sintered metal and a shaft member inserted on the inner periphery of the bearing member. When the shaft member rotates, a dynamic pressure action is generated in the lubricating fluid in the bearing gap by the herringbone-shaped dynamic pressure grooves formed on the inner peripheral surface of the bearing member, and the shaft member is supported in a non-contact manner so as to be rotatable in the radial direction. A radial bearing is provided. As described above, as a method of forming the dynamic pressure groove on the inner periphery of the bearing member formed of sintered metal, for example, as in Patent Document 2, the motion formed on the outer peripheral surface of the core rod at the time of forming the sintered metal. There is a type in which a core rod and a sleeve are released from each other by using a spring back of a sleeve after a pressure groove-shaped mold is transferred to an inner peripheral surface of the sleeve.
Japanese Patent Laid-Open No. 2002-61637 JP 10-306827 A JP 2004-316712 A

  However, the dynamic pressure groove forming by the method described in Patent Document 2 may cause a problem depending on the bearing size and the like. For example, in a bearing member used in a bearing device having a shaft diameter of 1 mm or less, such as a bearing device used in a micro fan motor, the spring back amount (expansion amount) of the bearing member is small. There is a possibility that the pressing groove forming part interferes with each other and it becomes difficult to release. Moreover, since the dynamic pressure groove shape is generally complicated, it is difficult to form a molding die corresponding to the dynamic pressure groove shape on an extremely fine core rod.

  Also, in a bearing member formed of a porous material such as sintered metal, the lubricating oil whose pressure is increased by the dynamic pressure action escapes from the surface opening of the bearing member to the inside, so-called “dynamic pressure relief”. Occurs. In particular, in the microminiature bearing member as described above, the influence on the bearing performance due to the dynamic pressure loss becomes large. In addition, since sintered metal generally has a large wear against contact sliding, for example, when the dynamic pressure bearing device is started and stopped, the bearing member bearings are not sufficiently developed in the dynamic pressure action of the lubricating oil in the bearing gap. If direct contact between the surface and the shaft member occurs, the bearing surface and the surface of the shaft member opposed to the surface may be worn, and a stable bearing function may not be obtained over a long period of time.

  In order to avoid these problems caused by manufacturing the bearing member with sintered metal, it is conceivable to form the bearing member with resin as disclosed in Patent Document 3, for example. However, a resin bearing member does not have an oil supply function like a sintered metal bearing member, and particularly in a small bearing device, the amount of oil itself filled in the bearing gap is extremely small. Depending on the use conditions and the like, there is a risk of causing poor lubrication. In addition, since resin has a larger coefficient of linear expansion than metal, the dimensional change with temperature change is large, and the bearing performance deteriorates due to deterioration of bearing clearance accuracy and peeling due to a decrease in fixing force between members. There is a fear.

  An object of the present invention is to provide a bearing device capable of maintaining excellent bearing performance over a long period of time efficiently and at low cost, and is particularly suitable for a micro motor having a shaft diameter of 1 mm or less. The object is to provide a pressure bearing device.

In order to solve the above problems, the present invention is formed on any one of a shaft member, a bearing member having a shaft member inserted into an inner periphery thereof, an inner peripheral surface of the bearing member, and an outer peripheral surface of the shaft member. In the hydrodynamic bearing device having a non-round surface that is displaced stepwise and has a constant shape in the axial direction, at least a region of the non-round surface that is close to the other surface is formed of a resin material, The other region is formed of a porous material that can be refueled.

  Thus, in the present invention, a non-circular surface that is displaced stepwise in the circumferential direction and has a constant shape in the axial direction is formed on the inner peripheral surface of the bearing member. Thus, after molding the bearing member, when the mold is released from the inner periphery of the bearing member, the inner peripheral surface of the bearing member and the mold do not interfere with each other, and the inner peripheral surface of the bearing member is damaged. It can be avoided. In addition, since the non-circular surface faces the radial bearing gap, the gap width of the radial bearing gap changes in the circumferential direction. Therefore, as the shaft member rotates, the lubricating oil in the portion with the larger gap width has a smaller gap width. It is pushed into the part and dynamic pressure action occurs. Therefore, it is not necessary to form a complex-shaped dynamic pressure groove such as a herringbone, and the inner mold can be easily processed. From the above, the bearing member can be manufactured at low cost, and is particularly suitable for manufacturing a micro bearing member having a shaft diameter of 1 mm or less. On the contrary, the same effect can be obtained when the inner peripheral surface of the bearing member is formed into a perfect circle and the non-circular surface as described above is provided on the outer peripheral surface of the shaft member.

  Moreover, the area | region (henceforth an approach area | region) which approached the other surface among step-like non-round surfaces is formed with a resin material. Thus, since the region where the greatest pressure is generated is formed of the resin material, the dynamic pressure is not lost in this portion, and the dynamic pressure action can be obtained efficiently. This approach area is also a part that contacts the shaft member when starting and stopping the bearing device, and by forming it with a resin material instead of a sintered metal, the wear resistance against contact sliding is improved, and it is long-term. Thus, stable bearing performance can be maintained.

Further, since a portion other than a portion formed of a resin material (hereinafter referred to as a resin portion) in a non-round surface is formed of a porous material, a portion formed of the porous material (hereinafter referred to as porous) The lubricating oil is successively supplied to the radial bearing gap formed between the shaft member and the bearing member from the shaft member), so that a shortage of lubricating oil in the radial bearing gap can be prevented. Dynamic pressure loss occurs due to the porous part facing the radial bearing gap, but the pressure of the lubricating oil is relatively low by arranging the porous part avoiding the approach area of the non-circular surface where the pressure is highest. Since the dynamic pressure loss occurs only at the part, there is little influence on the bearing performance. Also, since the resin material only forms part of the bearing member or shaft member, the variation in the radial bearing gap due to temperature changes can be reduced compared to the case where the entire member is formed of the resin material, and the bearing performance. The temperature dependence can be reduced. In particular, if the non-circular surface is formed by partially covering the porous portion with resin, the thickness of the resin portion can be made extremely small, so that fluctuations in the radial bearing gap due to temperature changes can be further suppressed. .

  In addition, the effect as described above is formed on any one of the shaft member, the bearing member with the shaft member inserted into the inner periphery, the inner peripheral surface of the bearing member and the outer peripheral surface of the shaft member, and is continuous in the circumferential direction. A non-circular surface having a portion displaced in the axial direction and having a fixed shape in the axial direction, and at least a region of the non-circular surface closest to the other surface is formed of a resin material, and The same can be obtained with a hydrodynamic bearing device in which the other region is formed of a porous material that can be refueled.

  In such a bearing device, if the bearing member integrally has a base portion for attaching the stator coil, the number of parts can be reduced and the combination of both can be reduced compared to the case where the base portion and the bearing member are separated. By reducing the attaching process, productivity can be improved and costs can be reduced.

  By attaching a fan to the shaft member, it can be used as a hydrodynamic bearing device for a fan motor, particularly for a micro fan motor having a shaft diameter of 1 mm or less.

  As described above, according to the present invention, a bearing device capable of maintaining excellent bearing performance over a long period of time can be obtained efficiently and at low cost.

  Hereinafter, embodiments of the present invention will be described.

  FIG. 1 is a sectional view conceptually showing a fan motor incorporating a fluid dynamic bearing device 1 according to the present invention. This fan motor is an ultra-small fan motor whose shaft diameter is set to 1 mm or less, for example, 0.8 mm, and is mounted on the dynamic pressure bearing device 1 that rotatably supports the shaft member 2 in a non-contact manner, and the shaft member 2. The rotor 3, the fan 4 formed integrally with the rotor 3 on the outer diameter side of the rotor 3, and the casing 5, for example, a stator coil 6 a and a rotor magnet 6 b that are opposed to each other via a gap in the radial direction (radial direction). Is a so-called radial gap type fan motor. The stator coil 6 a is attached to the outer periphery of the hydrodynamic bearing device 1 via the base portion 7, and the rotor magnet 6 b is attached to the rotor 3. When the stator coil 6a is energized, the rotor magnet 6b is rotated by the electromagnetic force between the stator coil 6a and the rotor magnet 6b, whereby the rotor 3 and the fan 4 rotate integrally with the shaft member 2. As a form of the fan motor, a so-called axial gap type fan motor in which the stator coil 6a and the rotor magnet 6b are opposed to each other with a gap in the axial direction (axial direction) can be used (not shown).

  FIG. 2 shows the hydrodynamic bearing device 1. The hydrodynamic bearing device 1 includes a shaft member 2, a bearing member 8 having the shaft member 2 inserted on the inner periphery thereof, and a base portion 7 provided on the outer periphery of the bearing member 8 and having a stator coil 6a attached to the outer peripheral surface thereof. Configured as the main part. In the following description, the side where the bearing member 8 is closed is the lower side, and the side where the bearing member 8 is opened is the upper side.

  The shaft member 2 is formed of a metal material such as stainless steel, for example. In the present embodiment, the shaft member 2 has a spherical convex portion 2b at the lower end, and the lower end of the spherical convex portion 2b and the inner bottom surface 85a of the bearing member 8 are brought into sliding contact with each other to thrust the shaft member 2. It constitutes a so-called pivot bearing that supports in the direction.

  The bearing member 8 is formed in a cup shape including a side portion 80 and a bottom portion 85. The side portion 80 is provided so as to protrude from the cylindrical inner peripheral surface 81a of the porous portion 81 toward the inner diameter side with a porous portion 81 formed into a cylindrical shape with a porous material, for example, a sintered metal containing copper as a main component. The resin portion 82 is formed (see FIG. 3).

  The inner peripheral surface 80a of the side portion 80 is formed in a non-circular shape that is displaced stepwise in the circumferential direction and has a constant shape in the axial direction. Thereby, the gap width of the radial bearing gap changes in the radial direction and is constant in the axial direction. Of the inner peripheral surface 80a as the non-round surface R, a region approaching the outer peripheral surface 2a of the shaft member 2 facing through the radial bearing gap (hereinafter referred to as an approach region R1) is an inner peripheral surface of the resin portion 82. A region formed by 82 a and separated from the outer peripheral surface 2 a of the shaft member 2 (hereinafter, a separation region R <b> 2) is formed by the inner peripheral surface 81 a of the porous portion 81.

  The bottom portion 85 of the bearing member 8, the resin portion 82 of the side portion 80, the base portion 7, and the casing 5 (hereinafter collectively referred to as a resin molding portion) are formed by injection molding of a resin with a porous portion 81 inserted therein. Is done. In this injection molding step, first, an inner mold in which a molding die corresponding to the shape of the resin portion 82 is provided on the outer peripheral surface is inserted into the inner periphery of the porous portion 81. And the integral part of the porous part 81 and the inner mold is inserted into the molding die, and the porous part 81, the inner mold and the resin molded part are integrally molded by injecting molten resin into the mold. Is done. At this time, since the molten resin enters the internal pores of the surface layer portion from the surface opening of the surface of the porous portion 81 and solidifies, the resin molded portion firmly adheres to the surface of the porous portion 81 by a kind of anchor effect. .

  As a resin material for the resin molded portion, particularly a resin material for the resin portion 82, a resin material excellent in wear resistance against contact sliding with the shaft member 2 and oil resistance to lubricating oil, such as LCP or PPS material, is suitable. Can be used for In addition, it is preferable to add a filler such as carbon fiber or glass fiber to the above resin because wear resistance is improved. In addition to these, various fillers such as a conductive filler and a release agent may be used alone or in admixture of two or more.

  After the injection molding, the inner mold is released from the integral part of the porous part 81, the inner mold, and the resin molded part, thereby completing the integrally molded article of the bearing member 8, the base part 7, and the casing 5. Since the inner peripheral surface 80a of the bearing member 8 formed in this way has a constant shape in the axial direction, the inner peripheral surface 80a and the molding die formed on the outer peripheral surface of the inner mold do not interfere with each other at the time of mold release. The inner mold can be released smoothly without damaging the surface 80a. In addition, the inner mold can be easily processed as compared with the case where a complex dynamic pressure groove such as a herringbone shape is formed. As described above, the bearing member 8 of the micro hydrodynamic bearing device 1 can be manufactured at low cost.

  When the shaft member 2 rotates, the lubricating oil in the gap between the radial bearing gaps having a relatively wide gap width, that is, the gap between the separation region R2 of the non-round surface R and the outer peripheral surface 2a of the shaft member 2 is removed. The pressure increases by being pushed into a gap having a relatively narrow width, that is, a gap between the approach region R1 of the non-round surface R and the outer peripheral surface 2a of the shaft member 2. The shaft member 2 is supported in a non-contact manner in the radial direction by the dynamic pressure action of the lubricating oil.

  In the bearing device 1 according to the present invention, the approach region R1 in which the largest pressure is generated is formed of a resin material among the inner peripheral surface 80a (non-circular surface R) of the bearing member 8. There is no slipping out, and a dynamic pressure effect can be obtained efficiently. Further, since the resin material is superior in wear resistance against contact sliding compared to the sintered metal, the inner peripheral surface 82a of the resin portion 82 when the dynamic pressure action is not sufficiently exhibited, such as when the bearing device is started and stopped. Wear due to contact sliding between the shaft member 2 and the outer peripheral surface 2a of the shaft member 2 can be suppressed, and stable bearing performance can be maintained over a long period of time.

  Further, since the portion other than the resin portion 82 is formed by the porous portion 81 in the inner peripheral surface 80a (non-round surface R) of the bearing member 8, the lubricating oil is sequentially supplied from the porous portion 81 to the radial bearing gap. The shortage of lubricating oil in the radial bearing gap can be prevented. In the inner peripheral surface 80a of the bearing member 8, the dynamic pressure loss occurs from the separation region R2 formed by the porous portion 81. However, since the generated pressure is lower than that of the approach region R1, it has an influence on the bearing performance. There are few. Further, since the non-circular surface R is provided by partially covering the inner peripheral surface 81a formed in the cylindrical porous portion 81 with a resin material, the thickness of the resin portion 82 is set so that the bearing member 8 is thick. The minimum width corresponding to the level difference between the approach region R1 and the separation region R2 formed on the inner peripheral surface 80a of the inner peripheral surface 80a, and variation in the radial bearing gap due to temperature change can be suppressed.

  The present invention is not limited to the above embodiment. For example, in the above-described embodiment, the case where the porous portion 81 is formed in a cylindrical shape is illustrated. However, as shown in FIG. 4, the porous portion 81 having a step-like inner peripheral surface is formed, and the inside of the small diameter is formed. The inner peripheral surface 80a of the bearing member 8 can also be formed by coating the peripheral surface 81a1 with resin. According to this, since the thickness of the resin portion 82 can be further reduced, the variation in the radial bearing gap due to the temperature change can be further suppressed. In FIG. 4, the resin coating is applied only to the small-diameter inner peripheral surface 81a1 of the inner peripheral surface of the porous portion 81. In addition to this, the small-diameter inner peripheral surface 81a1 and the large-diameter inner peripheral surface 81a2 of the porous portion 81 are provided. The step 81b formed between the two may be coated.

  Further, the shape of the non-round surface R formed on the bearing member 8 is not limited to the step shape. In the example shown in FIG. 5, the inner peripheral surface 80a of the bearing member 8 as the non-circular surface R includes three circular arc surfaces that are continuously displaced in the circumferential direction (so-called multi-arc bearings). Of this non-round surface R, at least a region closest to the outer peripheral surface 2 a of the shaft member 2 (hereinafter referred to as the closest region R 1) is formed by the inner peripheral surface 82 a of the resin portion 82. Further, a portion other than the resin portion 82 in the inner peripheral surface 80 a is formed by the porous portion 81. The centers of curvature O ′ of the three circular arc surfaces constituting the non-circular surface R are offset by the same distance from the axis center O of the bearing member 8 (shaft member 2). In each region defined by three arcuate surfaces, the radial bearing gap has a shape gradually reduced in a wedge shape in both circumferential directions. Therefore, when the shaft member 2 rotates, the lubricating oil in the radial bearing gap is pushed into the minimum width portion side (the closest approach region R1 side) reduced in a wedge shape according to the direction of the rotation, and the pressure increases. . The shaft member 2 is supported in a non-contact manner by the dynamic pressure action of the lubricating oil. Note that a deeper axial groove called a separation groove may be formed at the boundary between the three arc surfaces.

  FIG. 6 shows another example of the multi-arc bearing. Also in this example, the inner peripheral surface 80a of the bearing member 8 that becomes the non-circular surface R includes three arc surfaces, but the three arc surfaces are gradually wedged with respect to one direction in the circumferential direction. A reduced so-called taper bearing is formed. Of the non-round surface R, at least the closest region R1 is formed by the inner peripheral surface 82a of the resin portion 82. Further, a deeper axial direction G called a separation groove is formed at the boundary between the three arc surfaces. When the shaft member 2 rotates in a predetermined direction, the lubricating oil in the radial bearing gap is pushed into the minimum width portion side (the closest approach region R1 side) reduced to a wedge shape, and the pressure rises. The shaft member 2 is supported in a non-contact manner by the dynamic pressure action of the lubricating oil.

  FIG. 7 shows another example of the tapered bearing shown in FIG. In this example, in the configuration shown in FIG. 6, the predetermined regions θ on the closest approach region R1 side of the non-round surface R are respectively concentric with the axis center O of the porous portion 81 (shaft member 2) as the center of curvature. Consists of arcs. Accordingly, in each predetermined region θ, the gap width of the radial bearing gap is constant. The multi-arc bearing having such a configuration may be referred to as a tapered flat bearing.

  In the example shown in FIG. 6 and FIG. 7, the three arc surfaces are formed by the resin portion 82, and the other portion (separation groove G) is formed by the porous portion 81. The arc surface may be a composite structure of a resin material and a porous material. At this time, at least the closest region R <b> 1 is formed of the resin portion 82 among the circular arc surfaces. In this way, by exposing the porous portion 81 not only from the separation groove G but also from the arc surface, the area where the porous portion 81 is exposed to the radial bearing gap A can be increased, and Since it becomes easy to supply lubricating oil, lubricity can be improved.

  The multi-arc bearings in the above examples are so-called three-arc bearings, but are not limited to this, and so-called four-arc bearings, five-arc bearings, and multi-arc bearings composed of more than six arc surfaces are adopted. You may do it.

  Further, in the above embodiment, the case where the non-round surface R is formed on the inner peripheral surface 80a of the bearing member 8 is shown. On the contrary, the inner peripheral surface 80a of the bearing member 8 is formed into a perfect circle shape. In addition, the non-circular surface R can be provided on the outer peripheral surface 2a of the shaft member 2 facing this. In the example shown in FIG. 8, the outer peripheral surface 2a of the shaft member 2 constitutes a non-circular surface R that is displaced stepwise in the circumferential direction and has a constant shape in the axial direction. The outer peripheral surface 2a (non-circular surface R) of the shaft member 2 includes a porous body 21 having a cylindrical outer peripheral surface 21a and a resin provided to protrude from the outer peripheral surface 21a of the porous body 21 to the outer diameter side. And the portion 22. Of the non-circular surface R, a region R1 that is close to the inner peripheral surface 80a of the bearing member 8 that faces the radial bearing gap is formed by the outer peripheral surface 22a of the resin portion 22, and from the inner peripheral surface 80a of the bearing member 8 A separated region R <b> 2 is formed on the outer peripheral surface 21 a of the porous portion 21.

  Moreover, in said embodiment, although the resin part 82, the base part 7, and the casing 5 were shape | molded integrally, these can also be formed separately. In this case, when an oil-containing resin is used as the resin material of the resin portion 82, better lubricity can be obtained. Moreover, the material of the base part 7 and the casing 5 is not limited to resin, and metal materials such as brass and stainless steel can be used.

  Moreover, although the case where a sintered metal was used as a porous material which forms the porous part 81 was shown above, not only this but a porous resin can also be used, for example. In this case, since the resin material generally has a large dimensional change due to a temperature change or the like, for example, an appropriate amount of a material having a relatively small linear expansion coefficient such as metal powder or silica may be mixed with the oleoresin to suppress the overall linear expansion coefficient. preferable.

  In the above embodiment, an example is shown in which the upper end surface 81b of the porous portion 81 is exposed to the outside. For example, the resin molded portion can be molded so as to cover the upper end surface 81b of the porous portion 81. . In this case, oil leakage from the porous portion 81 to the outside can be prevented.

  Alternatively, a separate seal member can be disposed at the upper end of the bearing sleeve. In this case, a sealing effect that prevents leakage of oil from the upper end surface 81b of the porous portion 81 and prevents leakage of lubricating oil in the radial bearing gap by the seal space formed on the inner periphery of the seal member, and temperature A buffer function that absorbs thermal expansion of the lubricating oil due to the change can be obtained.

  Further, in the above-described embodiment, the case where the thrust bearing portion is configured by the pivot bearing is illustrated, but the thrust bearing portion is not limited thereto. For example, the shaft member 2 may have a lower end surface, and the dynamic pressure generating portion may be formed on the lower end surface or the inner bottom surface 85 a of the bearing member 8. As the shaft member 2 rotates, a dynamic pressure action is generated in the lubricating oil in the thrust bearing gap between the lower end surface of the shaft member 2 and the inner bottom surface 85a of the bearing member 8, and the shaft member 2 is supported in a non-contact manner in the thrust direction. A thrust bearing portion is formed. As the shape of the dynamic pressure generating portion, for example, a herringbone shape, a spiral shape, a step shape, or a corrugated shape can be considered.

  The bearing device of the present invention is not limited to a fan motor, but is rotated in a small motor for information equipment used under high-speed rotation, such as a spindle motor for driving a magneto-optical disk of an optical disk, or a polygon scanner motor of a laser beam printer. It can also be suitably used for shaft support.

It is sectional drawing which shows notionally the fan motor incorporating the dynamic pressure bearing apparatus 1. FIG. 1 is a sectional view of a hydrodynamic bearing device 1 according to an embodiment of the present invention. 3 is a cross-sectional view perpendicular to the axial direction of a bearing member 8 and a shaft member 2. FIG. It is sectional drawing perpendicular | vertical to the axial direction of the bearing member 8 and the shaft member 2 which concern on other embodiment. It is radial direction sectional drawing of the bearing member 8 and the shaft member 2 which concern on other embodiment (3 arc bearings). It is radial direction sectional drawing of the bearing member 8 and the shaft member 2 which concern on other embodiment (taper bearing). It is radial direction sectional drawing of the bearing member 8 and the shaft member 2 which concern on other embodiment (taper flat bearing). It is radial direction sectional drawing of the bearing member 8 and the shaft member 2 which concern on other embodiment (example which provided the non-round surface R in the shaft member 2 side).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Dynamic pressure bearing apparatus 2 Shaft member 4 Fan 5 Casing 7 Base part 8 Bearing member 80 Side part 81 Porous part 82 Resin part 85 Bottom part R Non-circular surface R1 Approaching area, closest approach area R2 Separation area G Separation groove

Claims (5)

A shaft member, a bearing member in which a shaft member is inserted into the inner periphery, and an inner peripheral surface of the bearing member and an outer peripheral surface of the shaft member are formed, and are displaced stepwise in the circumferential direction. In the hydrodynamic bearing device having a non-circular surface having a certain shape,
A hydrodynamic bearing device, characterized in that at least a region close to the other surface of the non-circular surface is formed of a resin material, and the other region is formed of a porous material that can be supplied with oil. A shaft member, a bearing member in which the shaft member is inserted into the inner periphery, a bearing member formed on one of the inner peripheral surface of the bearing member and the outer peripheral surface of the shaft member, and having a portion continuously displaced in the circumferential direction; And in the hydrodynamic bearing device having a non-circular surface having a constant shape in the axial direction,
A hydrodynamic bearing device, characterized in that, of a non-round surface, a region closest to at least the other surface is formed of a resin material, and the other region is formed of a porous material that can be refueled.   The hydrodynamic bearing device according to claim 1, wherein the non-round surface is formed by partially covering a porous material with a resin material.   The hydrodynamic bearing device according to claim 1, wherein the bearing member integrally has a base portion for attaching the stator coil.   The hydrodynamic bearing device according to claim 1, wherein a fan is attached to the shaft member.

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