JP2002122141A - Oil-impregnated sintered bearing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To sufficiently store lubricating oil with a simple and compact configuration, and to excellently feed the stored lubricating oil to a bearing part side. SOLUTION: Lubricating oil storage parts 13d and 13e are demarcated on both sides across a fixed part 13a by making use of an outer circumferential side of a bearing member 13 having a large circumferential length to store lubricating oil of sufficient quantity, and the lubricating oil stored in the lubricating oil storage parts 13d and 13e on the outer circumferential side of the bearing member 13 is sucked by an inner side of the bearing member 13 having the capillary force larger than that of the lubricating oil storage parts 13d and 13e, and fed to the bearing part side.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sintered oil-impregnated bearing device having a structure in which a bearing member in which lubricating oil is impregnated inside a porous sintered body is held by a bearing holder.

[0002]

2. Description of the Related Art In general, a sintered oil-impregnated bearing device in which a shaft member is rotatably supported by a sintered oil-impregnated bearing shaft member is widely used in various kinds of apparatuses.
In this sintered oil-impregnated bearing device, for example, a hollow cylindrical bearing member 1 as shown in FIG. 5 is formed from a porous sintered body having a large number of pores. An appropriate lubricating oil is impregnated on the inner side of the porous sintered body. In such a bearing member 1, the outer peripheral side of the bearing member 1 is a fixed portion, and the fixed portion on the outer peripheral side is
It is fixed to the inner peripheral surface side of the bearing holder 2 by press fitting or the like.

On the other hand, on the inner peripheral surface side of the bearing member 1, for example, two bearing portions 1a, 1a are provided, and the bearing surface of each bearing portion 1a and the shaft member (not shown) are provided. Since the above-described lubricating oil is interposed between the bearing member and the bearing surface provided on the outer peripheral surface side, the shaft member is rotatably supported inside the bearing member 1 described above. I have.

[0004]

As described above, in the sintered oil-impregnated bearing device, it is premised that the lubricating oil is always interposed between the shaft member and the bearing member. It is necessary to keep the lubricant for a long time. However, in the above-described conventional device, it is difficult to store a sufficient amount of lubricant in the vicinity of the bearing portion, and even if a configuration in which lubricant is stored is adopted,
There is a problem that the lubricant cannot be supplied to the bearing portion side.

[0005] Such a problem is extremely important in a hydrodynamic bearing device in which a dynamic pressure is generated for lubricating oil. The bearing life is greatly affected by the evaporation or deterioration of the lubricating oil. Therefore, it is desired to keep a sufficient amount of lubricating oil. In particular, in a tapered hydrodynamic bearing device, a step hydrodynamic bearing device bearing, or the like, which easily causes an outward leakage in the axial direction, it is a major problem because it is difficult to secure lubricating oil.

Accordingly, the present invention provides a simple and compact configuration,
It is an object of the present invention to provide a sintered oil-impregnated bearing device that can sufficiently store lubricating oil and can supply the stored lubricating oil to the bearing portion satisfactorily.

[0007]

According to a first aspect of the present invention, there is provided a sintered oil-impregnated bearing device according to the first aspect of the present invention. Since the bearing surfaces on the peripheral surface side are arranged to face each other with the bearing gap therebetween, a bearing portion that supports the shaft member and the bearing member so as to be relatively rotatable is configured, and the bearing member includes: An oil-impregnated bearing in which lubricating oil is impregnated inside a porous sintered body having a large number of pores, and the outer peripheral surface side of the bearing member is press-fitted to the inner peripheral surface side of the bearing holder. In a sintered oil-impregnated bearing device provided with a fixing portion for holding the whole, the outer peripheral surface of the bearing member and the inner peripheral surface of the bearing holder are formed on both sides of the fixing portion of the bearing member in the axial direction. Two oil reservoirs are defined by a gap formed therebetween In both cases, the gap size in the radial direction between these two oil reservoirs is formed larger than the diameter of the pores of the porous sintered body constituting the bearing member. The stored lubricant is
It is configured to be supplied toward the inside of the bearing member.

Further, in the sintered oil-impregnated bearing device according to the second aspect, the fixed portion of the bearing member according to the first aspect includes the second oil-impregnated bearing.
An oil passage that connects the two oil reservoirs is provided.

Further, in the sintered oil-impregnated bearing device according to the third aspect, the radial gap between the two oil reservoirs according to the first aspect is such that the capillary forces in the two oil reservoirs are different from each other. One side is formed larger than the other side,
The lubricating oil is configured to move from the oil reservoir on one side toward the oil reservoir on the other side by a difference in capillary force in the oil reservoir, and the diameter of the oil in the oil reservoir on the other side is changed. The gap size in the direction is formed larger than the diameter of the pores of the porous sintered body constituting the bearing member, so that the lubricating oil stored in the oil reservoir on the other side, It is configured to be supplied toward the inside of the bearing member.

Further, in the sintered oil-impregnated bearing device according to a fourth aspect, the bearing portion according to the first aspect has one side and the other arranged corresponding to the one side and the other side oil reservoir, respectively. And the density of the porous sintered body of the bearing member at the portion constituting the one-side bearing portion is higher than the density of the porous sintered body at the portion constituting the other-side bearing portion. It is formed larger than the density of the bearing member of the body,
In the inside of the bearing member, the lubricating oil is configured to move from the bearing part on the other side having a large hole to the bearing part on the one side having a small hole.

On the other hand, in the sintered oil-impregnated bearing device according to the fifth aspect, the oil reservoir according to the first aspect has an outer peripheral diameter of the bearing member larger than that of the fixed portion at both sides of the fixed portion in the axial direction. Is also defined by the smaller diameter portion of the bearing member.

Further, in the sintered oil-impregnated bearing device according to claim 6, the oil reservoir portion according to claim 1 has an inner peripheral diameter of the bearing holder at a portion corresponding to both side portions sandwiching the fixing portion in the axial direction. Is defined by a large-diameter portion of the bearing holder that is larger than an inner peripheral diameter of the bearing holder at a portion corresponding to the fixing portion.

According to the sintered oil-impregnated bearing device of the first aspect having such a configuration, since the oil reservoir is defined by using the outer peripheral side of the bearing member having a large peripheral length, the oil reservoir is formed. In the reservoir, a sufficient amount of lubricating oil is stored, and the lubricating oil stored on the outer peripheral side of the bearing member moves toward the inner side of the bearing member having a larger capillary force than the oil reservoir. It is absorbed and supplied to the bearing part side.

According to the sintered oil-impregnated bearing device of the second aspect, when the lubricating oil in one of the two oil reservoirs is consumed, the lubricating oil in the other oil reservoir is consumed. It is supplied through an oil passage.

Further, according to the sintered oil-impregnated bearing device according to the third aspect, since the large gap size is provided, the amount of lubricating oil stored is large, but external leakage is relatively likely to occur from the oil reservoir on one side. The lubricating oil is moved toward the oil reservoir on the other side, which has a small gap size, so that the lubricating oil is less likely to leak out, so that the outside leak is prevented while storing a sufficient amount of the lubricating oil. It has become so.

Further, according to the sintered oil-impregnated bearing device according to the fourth aspect, the lubricating oil collected in the other oil reservoir having a small gap size becomes large after moving to the inside of the bearing member. Moving from the other bearing portion side having a hole toward the one bearing portion having a small hole,
Lubricating oil is supplied favorably not only to the bearing part on the other side but also to the bearing part on one side.

On the other hand, the above-mentioned oil reservoir according to claim 1 is
The invention is defined by any of the sintered oil-impregnated bearing devices according to claim 5 and claim 6.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a spindle motor used in a rotary drive of various media disks such as a CD-ROM will be described below.

The entire spindle motor for a rotary disk drive shown in FIG. 1 includes a stator set 10 as a fixed member and a rotating member axially mounted on the stator set 10. And a rotor set 20. In the stator set 10, a substantially hollow cylindrical bearing sleeve 13 as a dynamic pressure bearing member is inserted inside a bearing holder 12 fixed to a substantially central portion of a fixed substrate (base plate) 11. It is fixed by an adhesive not shown. The bearing sleeve 13 can be joined to the bearing holder 12 by press fitting or shrink fitting.

A stator core 14 made of a laminated body of electromagnetic steel sheets is fitted on a mounting surface provided on the outer peripheral side wall surface of the bearing holder 12. This stator core 1
A drive coil 15 is wound around each salient pole portion provided in 4.

Further, a rotary shaft 21 constituting the above-mentioned rotor set 2 is rotatably inserted into a bearing hole formed through the bearing sleeve 13 along the central axis.
The rotating shaft 21 in the present embodiment is formed from stainless steel.

On the inner peripheral surface of the bearing hole in the bearing sleeve 13, dynamic pressure surfaces are formed as convex portions at two locations in the axial direction. The radial dynamic pressure bearing portion RB is arranged so as to face the dynamic pressure surface formed on the surface in the radial direction, and in a minute bearing gap space between the two dynamic pressure surfaces.
1 and RB2 are respectively formed. Bearing sleeve 1 in each of these radial dynamic pressure bearing portions RB1, RB2
The dynamic pressure surface on the third side and the dynamic pressure surface on the rotary shaft 21 side are, for example,
A predetermined lubricating oil such as a lubricating oil or a magnetic fluid is injected into a bearing gap space formed by the small gap, which is circumferentially opposed with a small gap of about several μm.

Further, on the dynamic pressure surface on the bearing sleeve 13 side, a radial dynamic pressure generating groove having a shape such as a herringbone shape (not shown) is annularly recessed, for example, divided into two blocks in the axial direction. During rotation, the lubricating fluid is pressurized by the pumping action of the two radial dynamic pressure generating grooves to generate a dynamic pressure, and the dynamic pressure of the lubricating fluid together with the rotating shaft 21 causes the rotor hub 2 to be described later.
2 is configured to be axially supported while floating in the radial direction.

On the other hand, a pivot portion 21a which forms a part of a spherical surface is provided at the lower end of the rotary shaft 21 in the figure, and a thrust plate 16 is provided at an opening at the lower end side of the bearing holder 12 in the figure. A disk-shaped thrust receiving member 17 is mounted inside the thrust plate 16. The pivot 21a at the lower end of the rotary shaft 21 is arranged to be in point contact with the upper surface of the thrust receiving member 17 in the drawing, whereby the entire rotary shaft 21 is thrust. It is supported in the direction.

A boss 22a of an outer rotor type rotor hub 22 having a thin bottom and a dish shape is fixed to an upwardly protruding portion of the rotary shaft 21. The boss 22a extends radially outward from the boss. An annular cylindrical upright wall 22b is provided on the outermost peripheral portion of the rotor hub 22 that extends, and a drive magnet (permanent magnet) 23, which is also annularly formed, is formed on the inner peripheral surface of the cylindrical upright wall 22b. Is attached. The drive magnetized surfaces formed along the inner and outer peripheral surfaces of the annular drive magnet 23 are disposed so as to be closer to the salient pole portions of the stator core 14 from the radially outer side. .

Further, on the upper surface side of the rotor hub 22 in the figure, a hub base 24 as a disk mounting portion is provided. The hub base 24 is fixed so as to be inserted outside the boss portion 22a of the rotor hub 22. By inserting a disc mounting hole (not shown) through the hub base 24, The entire recording media disk is mounted in a state of being positioned in the radial direction.

On the other hand, the bearing sleeve 13 as the above-mentioned bearing member is formed of a porous sintered body having a large number of holes, and the above-mentioned dynamic pressure generating dynamic pressure is formed inside the porous sintered body. It constitutes an oil-impregnated bearing device impregnated with lubricating oil. In such a bearing sleeve 13, as shown in FIGS. 2, 3, and 4, a large diameter projecting outward in the radial direction is provided at a substantially central portion in the axial direction of the outer peripheral surface of the bearing sleeve 13. A fixed portion 13a having a shape is provided in an annular shape, and the fixed portion 13a is press-fitted to the inner peripheral surface side of the bearing holder 12 described above so that the entire bearing sleeve 13 is held. Have been.

The fixing portion 13 of the bearing sleeve 13
Small-diameter portions 13b and 13c having outer peripheral surfaces of the bearing sleeve 13 smaller in diameter than the fixing portion 13a are provided on both side portions of the fixing portion 13a.
And a step is formed between them. These small diameter portions 13b and 13c are formed by the radial dynamic pressure bearing portion RB described above.
1 and RB2, respectively.
An annular gap formed between the small-diameter portions 13b and 13c and the inner peripheral surface of the bearing holder 12,
Two oil reservoirs 13d and 13e are respectively defined. In these two oil reservoirs 13d and 13e, the above-mentioned lubricating oil for generating dynamic pressure is injected and stored, as shown particularly in FIG.

When lubricating oil is injected into the oil reservoirs 13d and 13e, the oil reservoirs 13d and 13e are filled with oil.
It is preferable that the lubricating oil is sufficiently applied to the inner wall surface of 13e in advance.

Further, these two oil reservoirs 13d, 13d
e, gaps α1, α2 in the radial direction at e (see FIG. 2)
Is set to be larger than the average diameter of the pores of the porous sintered body constituting the bearing sleeve 13, and each of the oil reservoirs is set in accordance with a difference in capillary force determined by such a dimensional relationship. The lubricating oil in 13 d and 13 e is configured to be supplied toward the inside of the bearing sleeve 13.

On the other hand, the fixing portion 13 of the bearing sleeve 13
Oil passages 13f, 13f for communicating the two oil reservoirs 13d, 13e with each other are provided in the entire length including a so as to extend in the axial direction. Each of these oil passages 13f
Are formed in a groove shape having an arcuate cross-sectional shape, and through the oil passages 13f, the oil sump 13
The lubricating oil in d is supplied toward the oil reservoir 13e on the lower side in the figure.

That is, the two oil reservoirs 13d,
13e, the radial gap sizes α1 and α2 are
In order to make the capillary forces in the two oil reservoirs 13d and 13e different from each other, the gap dimension α
1 is formed larger than the gap dimension α2 of the lower oil reservoir 13e in the figure (α1> 2), the upper oil reservoir 13d in the figure has a smaller capillary force, and the figure has a larger capillary force. Lubricating oil is supplied from the upper oil reservoir 13d toward the lower oil reservoir 13e according to the difference in capillary force between the oil reservoir 13e and the lower oil reservoir 13e.

The radial gap dimension α1 in the upper oil reservoir 13d is, for example, about 0.2 to 0.3 mm on one side, and the radial gap dimension α2 in the lower oil reservoir 13e is , And one side is about 0.05 to 0.2 mm. That is, these oil reservoirs 13d,
13e, the clearance dimensions α1 and α2
3 are formed larger than the average diameter of the pores of the porous sintered body, and the lubricating oil in both oil reservoirs 13d and 13e is formed according to the difference in capillary force generated between them. , And is supplied toward the inside of the bearing sleeve 13.

Further, the porous sintered body constituting the bearing sleeve 13 is formed so that the molding density changes along the axial direction.
It is formed so as to have a density higher than the density of the lower part in the figure. That is, by adopting processing means such as not performing the pressing step uniformly, the bearing sleeve 1
3, the size of the pores of the porous sintered body constituting the small-diameter shaped portion 13b on the upper side in the drawing is smaller than the small-diameter shaped portion 1
3c is formed so as to be smaller than the size of the pores of the porous sintered body, and large pores are formed inside the bearing sleeve 13 according to a difference in capillary force generated thereby. The lubricating oil is moved from the lower radial dynamic pressure bearing portion RB2 shown in the drawing to the upper radial dynamic pressure bearing portion RB1 in the drawing having small holes.

On the other hand, the aforementioned radial dynamic pressure bearing portion RB
The dimensions of the bearing gap in the bearing sleeve 1 and RB2 are
3 is formed smaller than the size of the pores of the porous sintered body, so that the lubricating oil present inside the bearing sleeve 13 causes the two radial dynamic pressure bearing portions RB1, The configuration is such that they are respectively supplied into the RB2.

As described above, in this embodiment, the size of the gap with respect to the lubricating oil, that is, the capillary force is reduced by the radial dynamic pressure bearing portions RB1 and RB2, the upper small diameter portion 13b of the bearing sleeve 13, and the lower side of the bearing sleeve 13. Small diameter part 1
3c, the lower oil reservoir 13e, and the upper oil reservoir 13d are set to be smaller in this order, so that the movement of the lubricating oil as shown in FIG. It is configured. As a result, lubricating oil is always supplied to both the radial dynamic pressure bearing portions RB1 and RB2.

According to the sintered oil-impregnated bearing device used in the spindle motor according to this embodiment having such a configuration, the oil reservoirs 13b, 13c are formed by utilizing the outer peripheral side of the bearing sleeve 13 having a large peripheral length. Is defined, a sufficient amount of lubricating oil is stored in the oil reservoirs 13b and 13c, and the lubricating oil stored on the outer peripheral side of the bearing sleeve 13 is Parts 13b, 13c
Is absorbed toward the inner side of the bearing sleeve 13 having a larger capillary force, and the radial dynamic pressure bearing portion RB
1, RB2.

Further, according to the sintered oil-impregnated bearing device according to the present embodiment, when the lubricating oil in the lower oil reservoir 13c of the two oil reservoirs 13b and 13c is consumed,
The lubricating oil in the oil reservoir 13b on the upper side in the figure is supplied through an oil passage 13f.

At this time, since the oil reservoir 13b on the upper side of the figure has a large gap dimension α1, the amount of accumulated lubricating oil is large, but external leakage is relatively easy to occur. I have. However, in the present embodiment, the oil reservoir 13c on the lower side of the drawing has a small gap dimension α2 as described above, so that external leakage of the lubricating oil is less likely to occur.
Since the lubricating oil is configured to move from b to the oil reservoir 13c on the lower side in the drawing, it is possible to store a sufficient amount of lubricating oil and prevent external leakage of the lubricating oil well. Has become.

In this embodiment, the oil reservoir 13c having a large capillary force is provided at a portion which is directed downward in normal use.
, The external leakage of the lubricating oil is more effectively prevented.

Further, according to the sintered oil-impregnated bearing device according to the present embodiment, the lubricating oil having the small gap dimension α2 and collected in the lower oil reservoir 13c in the figure moves to the inside of the bearing sleeve 13. After that, inside the bearing sleeve 13, the lower radial dynamic pressure bearing portion RB2 having large holes moves from the lower side to the upper radial dynamic pressure bearing portion RB1 having small holes. The lubricating oil is satisfactorily supplied not only to the lower radial dynamic pressure bearing portion RB2 but also to the upper radial dynamic pressure bearing portion RB1.

Although the embodiments of the present invention made by the inventor have been specifically described above, the present invention is not limited to the above-described embodiments, and can be variously modified without departing from the gist thereof. Needless to say.

For example, each of the oil reservoirs 13d and 13e in the above-described embodiment is a fixing portion 13a of the bearing sleeve 13.
The outer diameter at both axial side portions of the fixing portion 13a
Is defined by making it smaller than
An oil reservoir is defined between the bearing sleeve 13 and the outer peripheral surface of the bearing sleeve 13 by enlarging the inner peripheral diameter of the bearing holder 12 at portions corresponding to both sides sandwiching the fixing portion 13a of the bearing sleeve 13 in the axial direction. It is also possible to configure so that

By providing an oil groove extending in the radial direction on the axial end face of the bearing sleeve 13 described above,
Radial dynamic pressure bearing portion RB on the inner peripheral side and oil reservoir 1 on the outer peripheral side
If the configuration is such that 3d or 13e is communicated, the lubricating oil overflowing from the radial dynamic pressure bearing portion RB side to the outside can be moved to the oil reservoir portions 13d and 13e without waste, which is convenient. Good.

Furthermore, if the axial end face of the bearing sleeve 13 is arranged so as to cover the washer, the lubricating oil is easily held inside by the action of the capillary force generated in the narrow space defined by the washer. Thus, the supply of the lubricating oil to the radial dynamic pressure bearing portion RB side is performed more smoothly.

Further, as shown particularly in FIG. 4, the boss 22a of the rotor hub 22 is
3 and the bearing holder 1
If the second peripheral wall is raised in the axial direction and disposed so as to face the outer peripheral side wall surface of the boss portion 22a of the rotor hub 22 from the radially outward side, the peripheral wall leaks from the end surface side of the bearing sleeve 13. The lubricating oil can be transmitted to the peripheral wall of the bearing holder 12 and can be recovered to the oil reservoirs 13d and 13e without waste.

In the above-described embodiment, the CD-ROM
Although the present invention is applied to a spindle motor for a disk drive device, the present invention is not limited to this, and various media disks such as a hard disk, a floppy (registered trademark) disk, and a DVD are used. The present invention can be similarly applied to a sintered oil-impregnated bearing device used for a motor to be driven to rotate and other various devices.

Further, the sintered oil-impregnated bearing device to which the present invention is applied is not limited to the hydrodynamic bearing device as in the above-described embodiment, but is a device using a sliding bearing member such as a metal bearing. Can be similarly applied.

[0049]

As described above, in the sintered oil-impregnated bearing device according to the present invention, the oil sump portions are defined on both sides of the fixed portion by using the outer peripheral side of the bearing member having a large circumferential length. While storing a sufficient amount of lubricating oil, the lubricating oil stored in the oil reservoir on the outer peripheral side of the bearing member is absorbed inside the bearing member having a larger capillary force than the oil reservoir, Since the lubricating oil is smoothly supplied to the bearing part, the lubricating oil can be sufficiently stored with a simple and small configuration, and the stored lubricating oil can be satisfactorily stored in the bearing part. Thus, the bearing characteristics of the bearing device can be stably maintained over a long period of time.

In the sintered oil-impregnated bearing device according to the present invention, when the lubricating oil on one of the two oil reservoirs is consumed, the lubricating oil in the other oil reservoir is supplied through the oil passage. The configuration described above allows the above-described effects to be further enhanced.

Further, the sintered oil-impregnated bearing device according to the present invention has a small gap size from one oil reservoir on the one side where a large amount of lubricating oil is stored, but external leakage is relatively likely to occur. By adopting a configuration in which the lubricating oil is moved toward the oil reservoir on the other side where leakage is unlikely to occur, the lubricating oil is stored in a sufficient amount and the lubricating oil is prevented from leaking outside. In addition, the above-described effects can be further improved, and the problem due to external leakage of the lubricating oil can be eliminated.

Further, in the sintered oil-impregnated bearing device according to the present invention, after the lubricating oil collected in the other oil reservoir having a small gap size is moved to the inside of the bearing member,
Inside the bearing member, the lubricating oil is favorably supplied to both bearing portions by moving from the other bearing portion side having a large hole to the one bearing portion having a small hole. Therefore, in addition to the effects described above, the bearing characteristics can be further improved.

[Brief description of the drawings]

FIG. 1 shows a CD- equipped with a hydrodynamic bearing device to which the present invention is applied.
FIG. 2 is an explanatory longitudinal sectional view showing a structural example of a ROM drive motor.

FIG. 2 is an explanatory longitudinal sectional view showing a structure of a bearing portion of a dynamic pressure bearing device used in the motor shown in FIG.

FIG. 3 is an external perspective explanatory view showing the shape of the bearing member shown in FIG. 2;

FIG. 4 is a partially enlarged longitudinal sectional view showing a relationship between clearance dimensions in a bearing portion and a moving direction of lubricating oil.

FIG. 5 is an explanatory longitudinal sectional view showing a structure of a bearing portion in a general sintered bearing device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Stator set 12 Bearing holder 13 Bearing sleeve (bearing member) 13a Fixed part 13d, 13e Oil storage part 13f Oil passage 13b, 13c Bearing part 20 Rotor set 21 Rotation shaft α1, α2 Gap size RB Radial dynamic pressure bearing part

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3J011 AA07 BA02 CA01 DA01 JA02 KA02 LA01 MA12 MA24 PA03 RA03 SB19 5H605 BB05 BB10 BB14 CC04 EB03 EB06 EB13 EB17 EB21 GG04

Claims (6)

[Claims] An inner peripheral surface of a hollow cylindrical bearing member is opposed to a bearing surface on an outer peripheral surface side of the shaft member via a bearing gap. A bearing portion for supporting the bearing member so as to be relatively rotatable is configured, wherein the bearing member is an oil-impregnated bearing in which lubricating oil is impregnated inside a porous sintered body having a large number of holes. In addition, in a sintered oil-impregnated bearing device provided with a fixing portion which is pressed into an inner peripheral surface side of a bearing holder and which holds the entire bearing portion on an outer peripheral surface side of the bearing member, the fixing portion of the bearing member is provided. On both sides sandwiched in the axial direction,
Two oil reservoirs are defined by a gap formed between the outer peripheral surface of the bearing member and the inner peripheral surface of the bearing holder, and the radial gap between these two oil reservoirs is: By being formed larger than the diameter of the pores of the porous sintered body forming the bearing member, the lubricating oil stored in each of the oil reservoirs is directed toward the inside of the bearing member. A sintered oil-impregnated bearing device characterized by being supplied. 2. The sintered oil-impregnated bearing device according to claim 1, wherein an oil passage for communicating the two oil reservoirs is provided in a fixing portion of the bearing member. 3. The radial gap between the two oil reservoirs is formed such that one side is larger than the other so that the capillary forces in the two oil reservoirs are different from each other. The lubricating oil is configured to move from the oil reservoir on one side toward the oil reservoir on the other side, and the radial gap size in the oil reservoir on the other side is determined by the difference By being formed larger than the diameter of the pores of the porous sintered body constituting the bearing member, the lubricating oil stored in the oil reservoir on the other side is located inside the bearing member. The sintered oil-impregnated bearing device according to claim 1, wherein the sintered oil-impregnated bearing device is configured to be supplied to the bearing. 4. The bearing portion includes two bearing portions on one side and the other side arranged corresponding to the oil reservoir portions on the one side and the other side, respectively, and constitutes the bearing portion on the one side. The density of the porous sintered body of the bearing member at the portion where the bearing member is formed is higher than the density of the porous sintered body of the bearing member at the portion forming the bearing portion on the other side. 2. The sintering method according to claim 1, wherein the lubricating oil is moved from the other bearing portion having a large hole to the one bearing portion having a small hole. Oil bearing bearing device. 5. The oil reservoir is defined by a small-diameter portion of the bearing member in which the outer peripheral diameter of the bearing member is smaller than that of the fixed portion on both sides of the fixed portion in the axial direction. The sintered oil-impregnated bearing device according to claim 1, wherein: 6. The oil reservoir, wherein an inner peripheral diameter of the bearing holder at a portion corresponding to both sides of the fixed portion in the axial direction is larger than an inner peripheral diameter of the bearing holder at a portion corresponding to the fixed portion. 2. The sintered oil-impregnated bearing device according to claim 1, wherein the large-diameter portion of the bearing holder has a large diameter.