JPH10184666A - Thrust dynamic pressure bearing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make lubrication favorable on the outer circumferential part by providing recessed parts for holding lubricant on the outer circumferential part positioned in the radial direction outside dynamic pressure generating grooves on at least either of a thrust bearing face and a thrust receiving face. SOLUTION: The outer circumferential face 33a in the radial direction outside dynamic pressure generating grooves 34 of a thrust receiving face 33 is provided with many recessed parts 35 for holding lubricant formed by coining, and the depth is shallower than that of the groove 34 so that the lubricant in the recessed part 35 is apt to discharge. When a shaft part 3 is rotated, lubricant between the face 33 and a thrust bearing face 41 is pushed in the grooves 34 by the pumping action of the rotating grooves 34, and dynamic pressure is generated in the lubricant so as to support the shaft part 3 in the axial direction. When a moment load is applied to the face 33 during rotation, the face 33 is tilted, and the edge part is partially contacted with the face 41. However because much lubricant exists on the outer circumferential part between the faces 35 and 41 due to the recessed parts 35, abrasion is hardly generated at the partial contact part, and the bearing outer circumferential part can be prevented from breaking down.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a thrust dynamic pressure bearing.

[0002]

2. Description of the Related Art A thrust dynamic pressure bearing is basically formed between a thrust bearing surface provided on a shaft portion and a thrust bearing surface of a shaft portion opposed to the thrust bearing surface. By filling the lubricant and rotating the shaft, a dynamic pressure is generated in the lubricant by a pumping action of a dynamic pressure generating groove formed in at least one of the thrust bearing surface and the thrust receiving surface. This supports the shaft portion in the axial direction.

FIG. 4 shows an example of a conventional thrust dynamic pressure bearing. In this thrust dynamic pressure bearing, a shaft portion 1 is formed by a shaft 11 and a flange 12 provided at one end of the shaft 11. The one end surface 13 of the flange 12 acts as a thrust receiving surface, and the thrust receiving surface 1
3, a plurality of herringbone-shaped dynamic pressure generating grooves 14 are formed. A lubricant (not shown) is filled between the flange 12 and the bearing 2 facing the flange 12, and a dynamic pressure is generated in the lubricant by the rotation of the shaft 1, and Part 1 is supported.

[0004]

By the way, the shaft 1
During rotation of the thrust bearing surface 21 and the thrust receiving surface 1
The lubricant filled between the thrust bearing surface 3 and the thrust bearing surface 13 is more likely to break the oil film in the portion radially outside of the dynamic pressure generating groove than the dynamic pressure generating groove. . In such a situation, as shown in FIG. 5, a moment load is applied to the thrust receiving surface 13 of the flange 12 to tilt the thrust receiving surface 13, and the edge portion of the thrust receiving surface 13 contacts the outer peripheral portion of the thrust bearing surface 21 of the bearing 2 (a so-called “thrust bearing”). In this case, there is a problem that the outer peripheral portions of the thrust surfaces 13 and 21 are gradually worn and damaged because lubrication at the contact portion is not sufficiently performed.

[0005] Therefore, an object of the present invention is to provide an outer peripheral portion of the thrust bearing surface so that even when the outer peripheral portion of the thrust bearing surface and the outer peripheral portion of the thrust bearing surface come into contact with each other due to a moment load, the outer peripheral portion of the thrust bearing surface is hardly worn. To provide a thrust dynamic pressure bearing capable of favorably lubricating the bearing.

[0006]

According to a first aspect of the present invention, there is provided a thrust dynamic pressure bearing, wherein a thrust bearing surface provided on a bearing portion faces a thrust receiving surface provided on a shaft portion. At least one of the thrust bearing surface and the thrust receiving surface has a dynamic pressure generating groove,
In a thrust dynamic pressure bearing in which a lubricant is filled between the thrust bearing surface and the thrust receiving surface, at least one of the thrust bearing surface and the thrust receiving surface is located radially outside the dynamic pressure generating groove. It is characterized in that it has a concave portion for holding the lubricant in the outer peripheral portion.

[0007] In the thrust dynamic pressure bearing of the first aspect, the lubricant is held by the recess formed in the outer peripheral portion of at least one of the thrust bearing surface and the thrust receiving surface. Then, a moment load is applied to the thrust receiving surface during rotation of the shaft portion, and the thrust receiving surface is tilted. When the edge of the thrust receiving surface comes into contact with the thrust bearing surface, the lubricant held in the concave portion serves as a contact portion. Lubrication is performed. As a result, wear on the outer peripheral portion between the thrust bearing surface and the thrust receiving surface is reduced as compared with the conventional case.

The thrust dynamic pressure bearing according to claim 2 is characterized in that the depth of the concave portion is smaller than the depth of the dynamic pressure generating groove. In this case, since the lubricant held in the concave portion easily comes out of the concave portion, lubrication of the contact portion when the thrust bearing surface comes into contact with the thrust bearing surface is favorably performed.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the illustrated embodiments.

FIG. 1 shows a thrust dynamic pressure bearing according to an embodiment of the present invention. As shown in FIG. 1A, the rotatable shaft portion 3 includes a shaft 31 and a flange 32 provided at one end of the shaft 31, and the flange 32 is opposed to the bearing portion 4. One end surface 33 of the flange 32 and the surface 41 of the bearing portion 4 facing the end surface 33 function as a thrust bearing surface and a thrust bearing surface, respectively. The flange 32 and the bearing portion 4 are rounded at edges on the thrust receiving surface 33 and the thrust bearing surface 41 side so as not to be easily damaged. The above flange 3
The space between the bearing 2 and the bearing portion 4 is filled with a lubricant (not shown) such as oil or grease.

The thrust receiving surface 33 of the flange 32
Has a plurality of dynamic pressure generating grooves 34 formed at predetermined intervals in the circumferential direction, as shown in FIG. Although these dynamic pressure generating grooves 34 are formed in a herringbone shape in the illustrated example, they may be formed in other shapes such as a spiral shape. Further, the thrust receiving surface 33 has an outer peripheral portion 33 a located radially outside the dynamic pressure generating groove 34.
In addition, a plurality of concave portions 35 for holding the lubricant are provided. The concave portion 35 is formed by coining, and the depth thereof is smaller than the depth of the dynamic pressure generating groove 34. The reason for this is to make it easier for the lubricant in the concave portion 35 to come out of the concave portion 35 and to sufficiently perform the function as the lubricant.

In the thrust dynamic pressure bearing having the above structure, when the shaft 3 rotates, the thrust bearing surface 33 and the thrust bearing surface 41 are formed by the pumping action of the dynamic pressure generating groove 34.
Is pushed into the dynamic pressure generating groove 34,
A dynamic pressure is generated in the lubricant, and the shaft portion 3 is axially supported by the dynamic pressure.

If a moment load is applied to the thrust receiving surface 33 during the rotation of the shaft portion 3, the so-called one-sided contact occurs in which the thrust receiving surface 33 is inclined and its edge portion hits the thrust bearing surface 41. However, the thrust receiving surface 33
Due to the large number of recesses 35 distributed in the outer peripheral portion 33a, a large amount of lubricant exists in the outer peripheral portion between the thrust receiving surface 33 and the thrust bearing surface 41, so that the edge portion of the thrust receiving surface 33 Even when the thrust bearing surface 41 comes into contact with the thrust bearing surface 41, wear is less likely to occur at the contact portion, and therefore, damage to the outer peripheral portion of the thrust dynamic pressure bearing can be prevented.

In the above thrust dynamic pressure bearing, FIG.
As shown in (B), the outer peripheral portion 33 of the thrust receiving surface 33
a, the recesses 35 are arranged in a row in the circumferential direction.
The arrangement is not limited to this. For example, the arrangement can be alternately arranged in two rows. Also, the recess 35
A circumferential groove connected in the circumferential direction may be used. The point is that the recesses 35 should be distributed as uniformly as possible in the outer peripheral portion 33a.

FIG. 2 shows another embodiment. In this embodiment, the concave portion 42 for holding the lubricant is provided with the thrust receiving surface 33.
Of the thrust receiving surface 33 instead of the outer peripheral portion of
Only the point formed on the outer peripheral portion 41a of the thrust bearing surface 41 corresponding to 3a differs from the thrust dynamic pressure bearing shown in FIG. The thrust dynamic pressure bearing of FIG. 2 has the same operation and effect as the thrust dynamic pressure bearing of FIG.

In the embodiment shown in FIGS. 1 and 2, the concave portions 35 and 42 for holding the lubricant are provided on either the thrust receiving surface 33 or the thrust bearing surface 41. However, both of these thrust surfaces are provided. By providing the recesses 35 and 42, respectively, a better wear reducing effect can be obtained.

The present invention is not limited to a thrust dynamic pressure bearing having a shaft portion and a flange provided at one end thereof as shown in FIGS. 1 and 2, for example, as shown in FIG. In addition, a flange 52 is provided at an end of the shaft 51, and a thrust dynamic pressure bearing surrounded by a housing 6 which acts as a bearing around the flange 52, and a shaft portion 7 as shown in FIG. However, it is needless to say that the present invention can also be applied to a thrust dynamic pressure bearing having no flange.

[0018]

As is clear from the above, according to the first aspect of the present invention, at least one of the thrust bearing surface on the bearing portion side and the thrust receiving surface on the shaft portion side is radially larger than the dynamic pressure generating groove. Since the outer peripheral portion has a concave portion for retaining lubricant, even if the thrust bearing surface is inclined and comes into contact with the thrust bearing surface, the contact portion is lubricated by the lubricant retained in the concave portion. Therefore, the outer peripheral portions of the thrust bearing surface and the thrust bearing surface are less likely to be worn. Therefore, the thrust bearing surface and the outer peripheral portion of the thrust receiving surface can be prevented from being damaged, as compared with a conventional thrust dynamic pressure bearing having no lubricant retaining recess radially outside the dynamic pressure generating groove. Life can be extended.

According to the second aspect of the present invention, since the depth of the concave portion for retaining the lubricant is made smaller than the depth of the dynamic pressure generating groove, the lubricant retained in the concave portion is outside the concave portion. Easy to get out. Therefore, it is possible to satisfactorily lubricate the contact portion when the thrust bearing surface and the thrust bearing surface are in contact with each other.

[Brief description of the drawings]

FIG. 1 is a view showing one embodiment of a thrust dynamic pressure bearing of the present invention, wherein (A) is a cross-sectional view of the thrust dynamic pressure bearing,
(B) shows the thrust receiving surface of the thrust dynamic pressure bearing.

FIG. 2 is a cross-sectional view of another embodiment of the present invention.

FIG. 3 is a view showing another embodiment of a thrust dynamic pressure bearing to which the present invention can be applied.

FIG. 4 is a view showing a conventional thrust dynamic pressure bearing.

FIG. 5 is a diagram showing a state in which the thrust receiving surface is inclined and hits the thrust bearing surface due to a moment load in the thrust dynamic pressure bearing of FIG. 4;

[Explanation of symbols]

3: Shaft, 4: Bearing, 33: Thrust receiving surface, 33 a
... outer peripheral portion, 34 ... dynamic pressure generating groove, 35 ... concave portion, 41 ... thrust bearing surface, 41a ... outer peripheral portion, 42 ... concave portion.

Claims (2)

[Claims] 1. A thrust bearing surface provided on a bearing portion faces a thrust receiving surface provided on a shaft portion, and at least one of the thrust bearing surface and the thrust receiving surface has a dynamic pressure generating groove. Further, in a thrust dynamic pressure bearing in which a lubricant is filled between the thrust bearing surface and the thrust receiving surface, at least one of the thrust bearing surface and the thrust receiving surface is radially outside the dynamic pressure generating groove. A thrust dynamic pressure bearing having a concave portion for holding a lubricant in an outer peripheral portion located at a position (1). 2. The thrust dynamic pressure bearing according to claim 1, wherein a depth of said concave portion is smaller than a depth of said dynamic pressure generating groove.