JP2000346055A - Bearing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent air entrainment to suppress sway of a shaft and elongate lifetime by providing an air entrainment preventing layer for preventing air entrainment into a dynamic pressure generating groove. SOLUTION: A center part 4 of a bearing 1 consists of an air entrainment preventing layer 5 and a dynamic pressure generating layer 6. The air entrainment preventing layer 5 has multiple air relief groove 7 provided adjacent to each of multiple V-shaped dynamic pressure generating grooves 8. The dynamic pressure generating layer 6 has multiple dynamic pressure generating grooves 8 and supporting surfaces 9 provided at a specified interval in a circumferential direction of an inner peripheral surface of the bearing 1. Pressure distributes such that the dynamic pressure becomes highest near the center of the dynamic pressure generating layer 6 at the time of rotation of a shaft or the bearing 1. Although air is entrained into the air relief groove 7 by rotation of the shaft or the bearing 1, the air is discharged outwards by dynamic pressure generated at the air relief groove 7. Air entrainment into the dynamic pressure generating grooves 8 causing sway of the shaft can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a bearing used for a high-speed rotation motor.

[0002]

2. Description of the Related Art FIG. 35 is a schematic sectional view showing the structure of a conventional dynamic pressure bearing. 51 is a bearing, 52 is an upper end, 5
3 is a lower end, 57 is a dynamic pressure generating groove, 58 is a support surface, and 55 is a center. The dynamic pressure generating groove 57 generates a dynamic pressure in the oil as the shaft or the bearing rotates. Then, a load during rotation can be received by the dynamic pressure.

[0003]

However, when air is drawn into the dynamic pressure generating groove 57, there is a problem that the normal flow of oil is obstructed and the shaft runout increases. Therefore, for example, Japanese Patent Application Laid-Open No. 63-1811 proposes a bearing in which at least one or more circumferential grooves are arranged near the upper end and the lower end of a herringbone type groove constituting a dynamic pressure generating groove. Have been. According to this, it is possible to prevent air from entering the center of the herringbone groove, but when air bubbles enter the circumferential groove, the air bubbles are likely to unite and become large, In addition, since dynamic pressure does not occur in the circumferential groove portion, stable dynamic pressure does not occur,
In some cases, shaft run-out cannot be prevented.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems, and to provide a bearing having a long life by preventing air from getting into the dynamic pressure generating groove, suppressing shaft runout.

[0005]

According to a first aspect of the present invention, there is provided a bearing for supporting a shaft loosely inserted in a shaft hole. A dynamic pressure generating layer having a plurality of dynamic pressure generating grooves provided at predetermined intervals in a circumferential direction; and a dynamic pressure generating layer provided adjacent to at least one end face of the bearing to prevent air from getting into the dynamic pressure generating grooves. It has an air entrapment prevention layer.

[0006] The invention described in claim 2 is the invention according to claim 1.
In the invention described in (1), the air entrapment prevention layer has a plurality of air release grooves provided adjacent to each of the plurality of dynamic pressure generation grooves.

[0007] The invention according to claim 3 provides the invention according to claim 1.
Or 2) the air entrapment prevention layer has a surface porosity α of 10 to 30%, the dynamic pressure generating layer has a surface porosity β of 0 to 20%, and α> β. There is a feature.

[0008] The invention described in claim 4 is the invention according to claim 3.
Wherein the air entrainment preventing layer is an isolation layer for isolating the end face of the bearing from the dynamic pressure generating groove.

The invention described in claim 5 is the first invention.
In the invention according to any one of the above-described embodiments, the air entrainment prevention layer has two air entrapment prevention layers, and at least one of the widths L1 and L2 of the air entrapment prevention layer is the width L3 of the dynamic pressure generation layer
Satisfies the relationship of 0.02 × L3 to L3, and
Effective inner diameter L of the above bearing and 0.5L <L1 + L2 + L3
≦ 1.5L.

The invention described in claim 6 is the first invention.
In the invention described in any one of the above-described embodiments, the depth h3 of the dynamic pressure generating groove and the clearance c between the shaft and the inner peripheral surface satisfy a relationship of 0.5 ≦ h3 / c ≦ 5. Features.

[0011] The invention described in claim 7 is the first invention.
7. The invention according to any one of Items 6 to 6, wherein the dynamic pressure generating layer includes at least one V-shaped dynamic pressure generating groove provided in an axial direction of an inner peripheral surface of the bearing. .

According to an eighth aspect of the present invention, in the first aspect of the present invention, the air release groove formed by pressing from above and below is provided. It is characterized by having.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. <First Embodiment> FIGS. 1 and 3 are longitudinal sectional views of a bearing according to a first embodiment of the present invention. The bearing 1 has an upper end 2, a lower end 3, and a center 4 on an inner peripheral surface thereof. The central part 4 is composed of an air entrainment preventing layer 5 and a dynamic pressure generating layer 6. The air entrapment prevention layer 5 has a plurality of air escape grooves 7 provided adjacent to each of the plurality of V-shaped dynamic pressure generation grooves 8. The dynamic pressure generating layer 6 includes a plurality of dynamic pressure generating grooves 8 and support surfaces 9 provided at predetermined intervals in a circumferential direction of the inner peripheral surface of the bearing.
have. During rotation of the shaft (not shown) or the bearing, the dynamic pressure has a pressure distribution such that it becomes highest near the center of the dynamic pressure generating layer 6. The air is caught in the air escape groove 7 by the rotation of the shaft or the bearing,
The air is discharged outward by the dynamic pressure generated in the air release groove 7. Therefore, the dynamic pressure generating groove 8 causing the shaft runout
It is possible to prevent air from being trapped. The dynamic pressure generating groove may be V-shaped or arcuate as long as high dynamic pressure can be generated at the center of the dynamic pressure generating layer.

FIG. 2 shows a modification of the first embodiment, in which the air escape groove 10 and the dynamic pressure generation groove 8 are separated. By separating the air escape groove 10 and the dynamic pressure generating groove 8, the effect of preventing air from getting into the dynamic pressure generating groove 8 can be further enhanced. It is preferable that there be at least one dynamic pressure generating groove in the axial direction. For example, FIG.
As shown in other modified examples of Nos. To 9, a plurality of V-shaped dynamic pressure generating grooves may be provided. .

Next, FIG. 10 is a longitudinal sectional view of the bearing according to the present embodiment. Here, L1 and L2 are the widths of the air entrapment preventing layers on both sides of the dynamic pressure generating layer, L3 is the width of the dynamic pressure generating layer, and L is the effective inner diameter. FIG. 11 (a),
(B) is a graph showing a relationship between L1 / L3, L2 / L3 and bearing rigidity. L1 or L2 is 0.02 × L3
If the relationship of <L1, L2 <L3 was satisfied, the bearing rigidity did not decrease. FIG. 12 shows the relationship between L1 + L2 + L3 and L, where 0.5L <L1 + L2 + L3 ≦ 1.5L
If the relationship was satisfied, the bearing stiffness did not decrease. here,
High bearing stiffness means. This shows that the shaft runout due to the eccentric load is small.

FIG. 13 is a schematic sectional view of the bearing according to the present embodiment in which the shaft is loosely inserted. And FIG.
4 (a) is a cross-sectional view along the line XIVa-XIVa in FIG. 13, where C is the clearance between the bearing and the shaft in the air entrainment prevention layer, and h1 and h2 are the depths of the air escape grooves. FIG. 14B is a diagram showing a line XIVb− in FIG.
In the cross-sectional view along XIVb, C indicates the clearance between the bearing and the shaft in the dynamic pressure generating layer, and h3 indicates the depth of the dynamic pressure generating groove.

FIG. 15 is a graph showing the relationship between δ (= h3 / c) and bearing stiffness. By setting δ in the range of 0.5 to 5, necessary and sufficient bearing stiffness can be obtained.

As still another modification of the present embodiment, as shown in FIG. 16, the width of the dynamic pressure generating groove may be tapered from the end face toward the center. Here, the width B1, B2 of the dynamic pressure generating groove near the air release groove 7
May be larger than the width B3 of the central portion of the dynamic pressure generating groove 8, and need not necessarily be the same.

Further, the depth of the dynamic pressure generating groove may be reduced from the end face toward the center. For example, FIG.
FIG. 7B is a vertical sectional view taken along line XVIII-XVIII in FIG. Here, the depths h1 and h2 of the dynamic pressure generating grooves near the air escape groove 7 need only be greater than the depth h3 of the dynamic pressure generating grooves 8, and need not necessarily be the same.

In the bearing according to the present embodiment, an air escape groove may be formed by pressing a jig having a plurality of convex portions on the outer peripheral surface of the end portion from above and below. In the case of a sintered oil-impregnated bearing, an air release groove may be formed during compression molding of a powder material.

<Second Embodiment> FIGS. 19 to 21 show a sintered oil-impregnated bearing according to a second embodiment of the present invention. In the case of a sintered oil-impregnated bearing, when the shaft or the bearing rotates, oil is supplied between the shaft and the bearing by the self-lubricating action. It is preferable to set the surface porosity of the portion to a predetermined range. FIG. 22 shows the relationship between the porosity α of the air entrapment prevention layer and the shaft runout when the surface porosity β of the dynamic pressure generating layer was changed when the bearing according to the present embodiment was used. Things. Here, the shaft runout on the vertical axis is a relative value with respect to a conventional bearing in which the air entrainment preventing layer is not provided and α and β are 10%. A large value indicates that the shaft runout is large. means. If α is in the range of 10 <α <30%, 0 <β <20%, and α> β, the effect of suppressing shaft runout is large.

In this embodiment, the dynamic pressure generating grooves are provided separately from both end faces of the bearing, the separating layer is used as an air entrapment prevention layer, and the surface porosity α of the air entrapment prevention layer is set to 1
0 to 30%, the surface porosity β of the dynamic pressure generating layer is 0 to 20%,
The structure is the same as that of the first embodiment except that α> β, and it is manufactured by the same method. Since the isolation layer can suppress direct contact between the dynamic pressure generating groove and external air when the shaft or the bearing rotates, it is possible to prevent air from getting into the dynamic pressure generating groove.

As still another modification of the second embodiment, a plurality of V-shaped dynamic pressure generating grooves 8 may be provided separately in the axial direction as shown in FIG. FIG.
25, a plurality of V-shaped dynamic pressure generating grooves 8 may be provided alternately and separately in the axial direction. Further, as shown in FIG. May be provided separately. In any case, it is possible to extend the region of the high pressure part of the dynamic pressure to the vicinity of the isolation layer 15.

<Third Embodiment> A bearing according to the present embodiment is the same as the first and second embodiments except that the air entrainment preventing layer 5 is provided only on one side of the dynamic pressure generating layer 6. And manufactured in a similar manner. 26 to 28 show examples. By arranging these two bearings such that the air entrapment preventing layer 5 is located above and below, respectively, and inserting the shaft loosely, the same effects as in the first and second embodiments can be obtained.

In the first to third embodiments, one bearing has been described, but a plurality of bearings may be used to support the shaft. For example, it is also possible to use two (FIG. 30) and three (FIG. 31) bearing portions 30 of FIG. 29 having the structure of FIG. Thus, even if a bearing is configured by using a plurality of bearing portions, the same effect as in the first and second embodiments can be obtained.

FIGS. 32 and 33 show the bearing of FIG. 1 according to the first embodiment, the bearing of FIG. 10 of the second embodiment, and FIG. 7 is a graph showing the results of examining the life of shaft runout using the sample of FIG. In the conventional bearing, the shaft runout rapidly increases from 100 hours and 200 hours, whereas in the bearing according to the present invention, the shaft runout does not change even after 500 hours, and a good air entrainment prevention effect is obtained. Was done.

[0027]

According to the first aspect of the present invention,
Since the air entrainment preventing layer is provided adjacent to at least one end face of the dynamic pressure generating layer, the entrainment of air into the dynamic pressure generating groove can be prevented, and shaft runout can be prevented, so that a long-life bearing can be provided.

According to the second aspect of the present invention, a plurality of air escape grooves are provided in the air entrapment prevention layer adjacent to each of the dynamic pressure generating grooves, so that the entrapped air passes through the air escape grooves. As a result, it is possible to prevent air from getting into the dynamic pressure generating groove.

According to the third aspect of the present invention, the surface porosity α of the air entrapment preventing layer is 10 to 30%, the surface porosity β of the dynamic pressure generating layer is 0 to 20%, and α > Β, air entrainment can be prevented.

According to the fourth aspect of the present invention, since the separating layer between the end face of the bearing and the dynamic pressure generating groove is an air entrainment preventing layer, direct contact between the dynamic pressure generating groove and external air is prevented. Since it is suppressed, it is possible to prevent air from entering the dynamic pressure generating groove.

According to the fifth aspect of the invention, at least one of the widths L1 and L2 of the air entrapment prevention layer is
Since 0.02 × L3 to L3 and the relationship of the inner diameter effective length L and 0.5L <L1 + L2 + L3 ≦ 1.5L is satisfied, stable rotation is performed.

According to the invention of claim 6, the depth h3 of the dynamic pressure generating groove and the clearance c between the shaft material and the inner diameter surface are set so as to satisfy the relationship of 0.5 ≦ h3 / c ≦ 5. Therefore, an appropriate dynamic pressure can be generated, and stable rotation can be performed.

According to the seventh aspect of the present invention, since at least one dynamic pressure generating groove is provided in the axial direction of the inner peripheral surface of the bearing, the high pressure portion of the dynamic pressure is extended to the vicinity of the air entrainment preventing layer. be able to.

According to the invention of claim 8, the air release groove can be formed by pressing from above and below, and the air release groove can be easily processed.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a bearing according to a first embodiment of the present invention.

FIG. 2 is a longitudinal sectional view showing a modified example of the bearing of FIG.

FIG. 3 is a longitudinal sectional view showing a modified example of the bearing of FIG. 1;

FIG. 4 is a longitudinal sectional view showing a modified example of the bearing of FIG.

FIG. 5 is a longitudinal sectional view showing a modified example of the bearing of FIG. 1;

FIG. 6 is a longitudinal sectional view showing a modified example of the bearing of FIG. 1;

FIG. 7 is a longitudinal sectional view showing a modified example of the bearing of FIG. 1;

FIG. 8 is a longitudinal sectional view showing a modified example of the bearing of FIG. 1;

FIG. 9 is a longitudinal sectional view showing a modification of the bearing of FIG. 1;

FIG. 10 shows a width L3 of the dynamic pressure generation layer and a width L of the air entrapment prevention layer in the bearing according to the first embodiment of the present invention.
1, L2, and a longitudinal sectional view showing an effective inner diameter L.

FIG. 11: a. 11 is a graph showing a relationship between L1 / L3 and L2 / L3 and bearing stiffness in the bearing of FIG.
b. L1 / L3 and L2 / L3 in the bearing of FIG.
6 is a graph showing the relationship between the bearing rigidity.

12 (L1 + L2 + L) in the bearing of FIG.
3) A graph showing the relationship between / L and bearing rigidity.

FIG. 13 is a schematic cross-sectional view showing the structure of the bearing according to the first embodiment of the present invention in which the shaft is loosely inserted.

14 is a longitudinal sectional view of the bearing in FIG. 14,
(A) is a cross-sectional view along line XIVa-XIVa, (b)
Is a cross-sectional view along the line XIVb-XIVb.

FIG. 15 is a graph showing a relationship between h3 (depth of the dynamic pressure generation groove) / c (clearance) and bearing rigidity in the bearing according to the first embodiment of the present invention.

FIGS. 16A and 16B are cross-sectional views of a modified example of the bearing according to the first embodiment of the present invention, wherein FIG. 16A is a longitudinal cross-sectional view and FIG. 16B is an enlarged view of FIG.

FIG. 17 is a cross-sectional view of a modified example of the bearing according to the first embodiment of the present invention, where (a) is a longitudinal cross-sectional view and (b) is (a).
FIG.

FIG. 18 is a sectional view taken along lines XVIII-XVIII of FIG. 17b.

FIG. 19 is a longitudinal sectional view showing a structure of a bearing according to a second embodiment of the present invention.

20 is a longitudinal sectional view showing a modified example of the bearing of FIG.

FIG. 21 is a longitudinal sectional view showing a modification of the bearing of FIG. 19;

FIG. 22 shows the relationship between the surface aperture ratio α of the air entrapment preventing layer and the shaft runout when the surface aperture ratio β of the dynamic pressure generating layer is changed in the bearing according to the second embodiment of the present invention. It is a graph.

FIG. 23 is a longitudinal sectional view showing a modified example of the bearing of FIG. 19;

FIG. 24 is a longitudinal sectional view showing a modified example of the bearing of FIG. 19;

FIG. 25 is a longitudinal sectional view showing a modified example of the bearing of FIG. 19;

FIG. 26 is a longitudinal sectional view showing a structure of a bearing according to a third embodiment of the present invention.

FIG. 27 is a longitudinal sectional view showing a modified example of the bearing of FIG. 26.

FIG. 28 is a longitudinal sectional view showing a modified example of the bearing of FIG. 26.

FIG. 29 is a longitudinal sectional view showing a modified example of the bearing of FIG. 1;

FIG. 30 is a longitudinal sectional view showing a modification of the bearing of FIG. 1;

FIG. 31 is a longitudinal sectional view showing a modified example of the bearing of FIG. 1;

FIG. 32 is a graph showing a result of a time change of shaft runout of the bearing of FIG. 1;

FIG. 33 is a graph showing a result of a time change of shaft runout of the bearing of FIG. 10;

FIG. 34 is a graph showing a result of a time change of a conventional bearing in contact with a shaft.

FIG. 35 is a longitudinal sectional view showing the structure of a conventional bearing.

[Explanation of symbols]

1, 21, 32, 33 bearing, 2 upper end, 3 lower end,
4 central part, 5 air entrapment prevention layer, 6 dynamic pressure generation layer, 8 dynamic pressure generation groove, 9 support surface, 7, 10, 11, 12,
13 air escape groove, 15 isolation layer, 16 communication groove, 2
0 shaft, 30 bearing part.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Ikuo Uemoto 12-32 Taiseicho, Neyagawa-shi, Osaka Japan Science Metallurgy Co., Ltd. (72) Seiichi Yokohata 12-32 Taiseicho, Neyagawa-shi, Osaka Japanese science F term (reference) in Metallurgy Co., Ltd. 3J011 AA20 BA02 CA02 DA01 PA10 QA20 RA03 SB19 5H605 AA04 BB05 CC04 EB06 GG21 5H607 AA04 BB01 CC01 GG01 GG15 KK10

Claims (8)

[Claims] 1. A bearing for supporting a shaft loosely inserted in a shaft hole, comprising: a dynamic pressure generating layer having a plurality of dynamic pressure generating grooves provided at predetermined intervals in a circumferential direction of an inner peripheral surface of the bearing; A bearing having an air entrapment prevention layer provided adjacent to at least one end face of the bearing and for preventing air from being entrained in the dynamic pressure generating groove. 2. The bearing according to claim 1, wherein said air entrapment prevention layer has a plurality of air release grooves provided adjacent to each of said plurality of dynamic pressure generation grooves. 3. The bearing is a sintered oil-impregnated bearing, wherein the air entrapment preventing layer has a surface porosity α of 10 to 30%, and the dynamic pressure generating layer has a surface porosity β of 0 to 20%. The bearing according to claim 1, wherein α> β. 4. The bearing according to claim 3, wherein the air entrainment preventing layer is an isolation layer that isolates the end face of the bearing from the dynamic pressure generating groove. 5. It has two said air entrapment prevention layers,
At least one of the widths L1 and L2 of the air entrapment prevention layer is 0.02 × L3 to L3
Is satisfied, and the effective inner diameter L of the bearing is equal to 0.
The bearing according to any one of claims 1 to 4, wherein a relationship of 5L <L1 + L2 + L3 ≦ 1.5L is satisfied. 6. The depth h3 of the dynamic pressure generating groove and the clearance c between the shaft and the inner peripheral surface are 0.5 ≦ h3 / c ≦
The bearing according to any one of claims 1 to 5, which satisfies the relationship of (5). 7. The bearing according to claim 1, wherein the dynamic pressure generating layer includes at least one dynamic pressure generating groove provided in an axial direction on an inner peripheral surface of the bearing. 8. The bearing according to claim 1, further comprising the air release groove formed by pressing from above and below.