JP2001200845A - Dynamic pressure bearing member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide dynamic pressure bearing members capable of ensuring an adequate circulation of lubricating oil between the dynamic pressure bearing body and a rotary shaft to efficiently generate dynamic pressure, and of suppressing leakage of lubricating oil. SOLUTION: A first stopper wall a1 and a second stopper wall a2 are respectively provided between a first chamfered part 6a provided at the opening part of bearing hole and a first groove forming region b1 adjacent to the first chamfered part, and between a second chamfered part 6b provided at the opening part of the bearing hole and a second groove forming region b2 adjacent to the second chamfered part. Thus, specified spacing are respectively ensured between the first chamfered part 6a and the first groove forming region b1, and between the second chamfered part 6b and the second groove forming region b2, and thus leakage of lubricating oil from between the base end side of dynamic pressure grooves 7a, 7b and the rotary shaft can be suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dynamic pressure bearing body constituting a dynamic pressure bearing, in which lubricating oil is impregnated to suitably lubricate a rotary shaft inserted into a bearing hole. The present invention relates to a dynamic pressure bearing.

[0002]

2. Description of the Related Art Since a dynamic pressure bearing can be used for a long time without lubrication, it is used as a bearing for a rotating shaft of various devices, for example, a spindle motor for a DVD (registered trademark) or a magnetic disk drive. Widely used. In such a dynamic pressure bearing, one or a plurality of dynamic pressure bearing bodies formed of a porous sintered alloy and impregnated with lubricating oil are used.

[0003] In this type of dynamic pressure bearing body, a bearing hole is provided in a dynamic pressure bearing body formed of a porous sintered alloy, and a rotating shaft having a smaller diameter than the bearing hole is provided in the bearing hole. Is inserted and used. The dynamic pressure bearing body includes a lubricating oil sucked out from a number of fine holes (oil-containing holes) in the bearing body by a pump action accompanying rotation of the rotating shaft, and a lubricating oil exuded by expansion caused by frictional heat. Are formed such that an oil film is formed in a sliding portion with the rotating shaft, so that the oil film can support the rotating shaft without trouble such as burning.

As shown in FIG. 5, there is known such a dynamic pressure bearing body in which a groove is provided in an inner peripheral surface of a bearing hole, that is, a bearing surface to generate a dynamic pressure. On this bearing surface 51,
The groove forming regions m1 and m2 are provided over the entire circumference. The groove forming region m1 extends from the chamfered portion 52 on the upper surface side to the smooth region n where no groove is formed at the center portion with respect to the rotation direction (R direction in the figure) of the rotating shaft (not shown), and has the front end in the R direction Is a region in which a plurality of dynamic pressure grooves 53a directed at a predetermined distance are formed at predetermined intervals. The groove forming region m2 extends from the chamfered portion 52b on the lower surface side in the R direction to the smooth region n at the center, and has a plurality of dynamic pressure grooves 53b whose front ends are directed in the rotation direction at predetermined intervals. Area. The dynamic pressure grooves 53a in these groove forming regions m1
And the dynamic pressure groove 53b in the groove forming region m2 are formed so as to be line-symmetric with respect to the central axis O of the dynamic pressure bearing body.

When the rotating shaft rotates in the direction R in the drawing, the lubricating oil impregnated in the dynamic pressure bearing body is sucked out from the bearing surface 51 or the chamfered portions 52a and 52b. At this time, the dynamic pressure groove 5
The lubricating oils 2a and 52b are formed so as to be inclined so that the front ends thereof are directed in the R direction, so that the lubricating oil is collected from the groove forming regions m1 and m2 toward the smooth region n. Therefore, a high dynamic pressure is generated in the smooth region n. Among them, the oil film is most likely to be formed at two points, the boundary between the groove forming area m1 and the smooth area n, and the boundary between the groove forming area m2 and the smooth area n, and the highest dynamic pressure is generated in these parts. I do. The rotating shaft can be extremely strongly supported at these two locations, and can suppress shaft deflection.

[0006]

By the way, in such a dynamic pressure bearing body, if the groove forming area is widened, the lubricating oil can be more easily collected in the smooth area, and a higher dynamic pressure can be generated. Therefore, the groove forming region is formed to have a large area so as to be continuous with the chamfered portion, and the base end side of the dynamic pressure groove and the chamfered portion are connected to each other, and the gap is large. Therefore, the lubricating oil is
In other words, the lubricating oil is less likely to be drawn into the groove forming region, and the lubricating oil is likely to leak. When a large amount of lubricating oil leaks from such a portion, the amount of lubricating oil impregnated in the dynamic pressure bearing body decreases, and as a result, the rotating shaft may be burned.

The present invention has been made in view of the above circumstances, and it is possible to efficiently generate dynamic pressure by appropriately circulating lubricating oil between a dynamic pressure bearing body and a rotating shaft and to prevent leakage of lubricating oil. An object of the present invention is to provide a suppressed dynamic pressure bearing body.

[0008]

According to the first aspect of the present invention,
A bearing hole is formed of a porous sintered alloy, is provided on one end face and the other end face, and is provided with a bearing hole through which a rotating shaft is inserted. A plurality of dynamic pressure grooves extending from the respective end surfaces to the central portion in the groove forming region, and having a plurality of dynamic pressure grooves oriented in the direction of rotation in the tip end direction at predetermined intervals in a circumferential direction. A stopper wall for suppressing leakage of lubricating oil from the base end side of each of the dynamic pressure grooves is provided on each end face side of the formation region.

[0009] With this configuration, the groove forming region and each end face side, that is, the opening of the bearing hole are not directly connected. Therefore, since a stopper wall for sealing leakage of lubricating oil is interposed between the end face side of the dynamic pressure groove in the groove forming area, that is, between the base end side and the opening, the base end side of the dynamic pressure groove and the rotating shaft The leakage of the lubricating oil from the space can be suppressed.

According to a second aspect of the present invention, there is provided the dynamic pressure bearing body according to the first aspect, wherein the groove forming region is provided on the first groove forming region provided on the one end surface side and on the other end surface side. A second groove forming region provided, and a smooth region which is smooth over the entire circumference is formed on the inner peripheral surface sandwiched between the first groove forming region and the second groove forming region. It is characterized by.

With this configuration, the lubricating oil sucked out from the first groove forming region and the second groove forming region is collected in the smooth region, and a high dynamic pressure is generated in the smooth region. Can be. In the smooth region, the vicinity of the boundary with the first groove forming region where the lubricating oil is collected and the second region
The highest dynamic pressure is generated at two places near the boundary with the groove forming area, and the rotating shaft can be supported most strongly at these two places. Thereby, the support rigidity of the rotating shaft can be increased and the shaft runout can be suppressed, so that the gap between the stopper wall and the rotary shaft can be made substantially constant, and the leakage of the lubricating oil due to the shaft runout can be suppressed.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of a dynamic pressure bearing according to the present invention will be described below with reference to FIGS. As shown in FIG. 1, the dynamic pressure bearing body 1 is formed of a porous sintered alloy, and has a bearing hole 2 through which a rotating shaft (not shown) is inserted.
Is a cylindrical integrally molded product. Therefore, a large number of voids are formed in the dynamic pressure bearing body 1, and the voids are also opened on the inner peripheral surface of the bearing hole 2, that is, the bearing surface 3. Lubricating oil is held in a hole in the dynamic pressure bearing body 1, and the lubricating oil is appropriately sucked from the bearing surface 3 of the bearing hole 2 slidably in contact with the rotating shaft, so that the rotating shaft and the bearing surface 3 And an oil film is formed between them.

As shown in FIG. 2, a bearing surface 3 is formed on the inner peripheral surface of the bearing hole 2 of the dynamic pressure bearing body 1 so as to face the outer peripheral surface of the rotating shaft. 1 stopper wall a
1, a first groove forming area b1, a smooth area c, a second groove forming area b2, and a second stopper wall a2. A first chamfered portion 6a is provided between the upper surface (one end surface) 4 of the dynamic pressure bearing body 1 and the first stopper wall a1, and a lower surface (other end surface) 5 of the dynamic pressure bearing body 1 and the second stopper wall are provided. a2
The second chamfered portions 6b are formed respectively.

The first groove forming region b1 extends from the upper surface 4 side to the central smooth region c with respect to the rotation direction of the rotating shaft, and has a plurality of dynamic pressure grooves 7a whose tip ends are directed in the rotation direction.
Are regions formed at predetermined intervals. The second groove forming region b2 extends from the lower surface 5 side to the central smooth region c with respect to the rotation direction of the rotation shaft, and a plurality of dynamic pressure grooves 7b whose front ends are directed in the rotation direction have predetermined intervals. This is the area formed by. The dynamic pressure grooves 7a in the first groove forming area b1 and the dynamic pressure grooves 7b in the second groove forming area b2 are formed so as to be line-symmetric with respect to the center axis O1 of the dynamic pressure bearing body 1. ing.

The dynamic pressure grooves 7a and 7b are concave portions having a U-shaped cross section as shown in FIG. The depth of the dynamic pressure grooves 7a and 7b is set to 1 to 10 μm, and preferably about 5 μm. The portion of the first groove forming region b1 where the dynamic pressure groove 7a is not formed is the back portion 8a.
The portion of the second groove forming region b2 where the dynamic pressure groove 7b is not formed forms a back portion 8b. These back portions 8a and 8b are smooth portions similarly to the smooth region c, and are portions where dynamic pressure is generated by the lubricating oil extracted with the rotation of the rotating shaft.

The smooth region c is a region having no dynamic pressure grooves and no irregularities. This is a region where a high dynamic pressure is generated by the lubricating oil collected by the first groove forming region b1 and the second groove forming region b2.

As shown in FIGS. 3A and 3B,
The first chamfered portion 6a is connected to both the upper surface 4 and the bearing surface 3 by approximately 45
It is provided so as to make a sense. The second chamfered portion 6b is provided so as to form an angle of about 45 degrees with both the lower surface 5 and the bearing surface 3. The first stopper wall a1 has a first
The second stopper wall a2 is formed so as to be continuous from the chamfered portion 6a and so as to be continuous from the second chamfered portion 6b. The first stopper wall a1 and the second stopper wall a2 are formed by the first chamfered portion 6a and the first groove forming region b.
1 and the second chamfered portion 6b and the second groove forming region b2
To prevent a leakage of circulating lubricating oil due to rotation of the rotating shaft. These first stopper wall a1 and second stopper wall a2
Is formed to have a tapered shape like the first chamfered portion 6a and the second chamfered portion 6b.
a, it has a tapered surface that forms an obtuse angle with respect to the second chamfered portion 6b. It is preferable that the angle formed with the bearing surface 3 is about 20 degrees or less. When the height of the first chamfered portion 6a and the second chamfered portion 6b, that is, the dimension in the axial direction of the rotating shaft is D, the first stopper wall a
1. It is preferable that the height of the second stopper wall a2 is set to 0.5 to 1.5D.

When the rotating shaft rotates in the direction R in the drawing, the lubricating oil impregnated in the dynamic pressure bearing body 1 is sucked from the bearing surface 3 of the bearing hole 2 or the first chamfered portion 6a and the second chamfered portion 6b. And the back part 8 which is a smooth part of the inner peripheral surface 3
Oil films of lubricating oil are formed between the rotating shafts a and 8b and the smooth region c, and a dynamic pressure is generated at these positions. At this time, the dynamic pressure grooves 7a and the dynamic pressure grooves 7b are formed so as to be inclined so that the leading ends are directed in the rotation direction, so that the lubricating oil is supplied to the first groove forming region b1 and the second groove forming region. It becomes possible to gather from the area b2 toward the smooth area c. Therefore, a high dynamic pressure is generated in the smooth region c. Among them, an oil film is most easily formed at two points, that is, the boundary between the first groove forming region b1 and the smooth region c and the boundary between the second groove forming region b2 and the smooth region c. The highest dynamic pressure occurs. The rotating shaft is extremely strongly supported at these two locations, and is also supported by the dynamic pressure generated in the smooth region c and the back portions 8a and 8b, so that the bearing rigidity is high.

The bearing surface 3 or the first chamfered portion 6a,
The lubricating oil sucked out from the chamfered portion 6b is collected from the first groove forming region b1 and the second groove forming region b2 toward the smooth region c, and the collected lubricating oil mainly moves from the smooth region c. It is sucked into the pressure bearing body 1 and returns. And
Both ends of the inner peripheral surface 3, that is, the upper surface 4
It flows toward the side or the lower surface 5 side. The lubricating oil that has flowed to the upper surface 4 side is from the vicinity of the first chamfered portion 6a or the first stopper wall a1, and the lubricating oil that has flowed to the lower surface 5 side is the second lubricating oil.
From the vicinity of the chamfered portion 6b or the second stopper wall a2,
Each will be sucked out. The sucked lubricating oil is supplied to the first groove forming region b1 and the second groove forming region b2.
It is sucked to the side and collected again in the smooth area c. In this manner, the lubricating oil is supplied to the inner peripheral surface 3 and the dynamic pressure bearing 1
Circulates inside.

The first chamfer 6a or the second chamfer 6
The lubricating oil sucked from b is sucked into the tapered first stopper wall a1 side or the second stopper wall a2 side. First stopper wall a1, second stopper wall a
2 is connected to the first groove forming region b1 and the second groove forming region b2 at an obtuse angle with respect to the first chamfered portion 6a and the second chamfered portion 6b, respectively. Therefore, the lubricating oil is easily drawn into the first groove forming region b1 and the second groove forming region b2. Also, the first stopper wall a1 and the dynamic pressure groove 7a
Or the second stopper wall a2 and the base end of the dynamic pressure groove 7b are connected at an obtuse angle.
It is easy to go from the stopper wall a1 to the dynamic pressure groove 7a or from the second stopper wall a2 to the dynamic pressure groove 7b. Therefore, leakage of lubricating oil can be suppressed.

In this embodiment, the first chamfered portion 6a and the second chamfered portion 6 provided at each of the openings of the bearing hole 2 are provided.
A first stopper wall a1 and a second stopper wall a2 are provided between the first groove forming region b1 and the second groove forming region b2 adjacent to b. Thus, the first
Dynamic pressure grooves 7a, 7b are formed in the chamfered portion 6a and the second chamfered portion 6b.
Are not connected, that is, a gap formed by the dynamic pressure grooves 7a and 7b is eliminated, so that leakage of lubricating oil from between the base ends of the dynamic pressure grooves 7a and 7b and the rotating shaft is suppressed. Can be. Further, the lubricating oil sucked out from the first groove forming region b1 and the second groove forming region b2 is collected in the smooth region c, and a high dynamic pressure is generated in the smooth region c. Near the boundary with the first groove forming area b1 where the lubricating oil is collected and the second groove forming area b2
The highest dynamic pressure is generated at two locations near the boundary between the two. Therefore, the rotation axis is
Since the support can be made strongest at the location, the support rigidity of the rotary shaft can be increased and the shaft runout can be suppressed, so that the gaps between the first stopper wall a1 and the second stopper wall a2 and the rotary shaft can be made substantially constant, and the shaft runout can be achieved. Leakage of the lubricating oil due to the occurrence of the above can be suppressed.

[0022]

As described above, according to the dynamic pressure bearing according to the present invention, the stopper wall for securing a predetermined interval between each end face side and the groove forming region is provided.
Therefore, it is possible to provide a dynamic pressure bearing body that can efficiently generate dynamic pressure by appropriately circulating lubricating oil between the dynamic pressure bearing body and the rotating shaft, and that suppresses leakage of lubricating oil.

[Brief description of the drawings]

FIG. 1 is a view showing one embodiment of a dynamic pressure bearing according to the present invention, and is a side sectional view of the dynamic pressure bearing.

FIG. 2 is a development view showing a bearing surface in FIG. 1;

3A and 3B are views showing a chamfered portion and a stopper wall in FIG. 2, wherein FIG. 3A is a cross-sectional view taken along line AA in FIG.
FIG. 3B is a sectional view taken along line BB in FIG. 2.

4 is a view showing a dynamic pressure groove in FIG. 2, and is a sectional view taken along line EE in FIG. 2;

FIG. 5 is a view showing an example of a conventional dynamic pressure bearing body, and is a developed view of a bearing surface.

[Explanation of symbols]

 Reference Signs List 1 dynamic pressure bearing body 2 bearing hole 3 bearing surface (inner peripheral surface) 4 upper surface (one end surface) 5 lower surface (other end surface) 6a first chamfered portion 6b second chamfered portion 7a, 7b dynamic pressure groove a1 first stopper wall a2 Second stopper wall b1 First groove forming region b2 Second groove forming region c Smooth region

Continuation of the front page (72) Inventor Junichi Iguchi 3-1, Koganecho, Niigata City, Niigata F-term (reference) in Niigata Works, Mitsubishi Materia Real Co., Ltd. 3J011 BA02 CA03 JA02 KA02 LA01 MA07

Claims (2)

[Claims] Claims: 1. A porous sintered alloy,
A bearing hole which is open at one end and the other end and through which the rotating shaft is inserted is provided, and a groove forming region is provided over the entire circumference on the bearing surface of the inner peripheral surface of the bearing hole. A plurality of dynamic pressure grooves extending at a predetermined distance from each other in the circumferential direction and extending toward the center of the groove in the rotation direction. A dynamic pressure bearing body, wherein a stopper wall for suppressing leakage of lubricating oil from a base end side of the pressure groove is provided. 2. The groove forming region includes a first groove forming region provided on the one end surface side and a second groove forming region provided on the other end surface side, and these first groove forming regions are provided. 2. The dynamic pressure bearing body according to claim 1, wherein a smooth region which is smooth over the entire circumference is formed on the inner peripheral surface sandwiched between the first groove and the second groove forming region.