JP2023079465A - Bearing member - Google Patents

Abstract

To provide a bearing member capable of suppressing leakage of lubricating fluid.SOLUTION: A bearing member 10 includes an inner peripheral face 11 opposed to an outer peripheral face of a shaft 20 at a space d therefrom. The bearing member 10 supports the shaft 20 so as to be relatively rotatable in a predetermined rotating direction while holding lubricating fluid 30 in the space d, At least one end of the inner peripheral face 11 is opened to an end face 15 in the axial direction of the bearing member 10. The end face 15 and the inner peripheral face 11 include a first inclined part 13 connected to the inner peripheral face 11 and diameter-enlarged as extending to the end face 15, a step part 12 connected to the first inclined part 13 and having a plane perpendicular to the axial direction, and a second inclined part 14 connected to the step part 12 and the end face 15 and diameter-enlarged as extending to the end face 15.SELECTED DRAWING: Figure 1

Description

The present invention relates to bearing members.

As a bearing device for a motor or the like that requires high rotational accuracy, there is known a dynamic pressure bearing that supports a load by generating dynamic pressure in a lubricating fluid film through relative sliding motion of the bearing (see, for example, Patent Documents 1).

In the fluid dynamic pressure bearing device disclosed in Patent Document 1, when the motor is driven, the first inner peripheral surface of the sleeve (bearing) and the shaft main body ( A dynamic pressure is induced in the lubricating oil interposed between the sleeve and the outer peripheral surface of the shaft), and a force supporting the sleeve in the radial direction of the shaft is generated.

However, the lubricating oil interposed between the inner peripheral surface of the bearing and the outer peripheral surface of the shaft may cause the inner peripheral surface of the bearing and the outer peripheral surface of the shaft to deteriorate due to the action of centrifugal force when the motor is driven and the pumping action due to vibration. It may leak to the outside from between If lubricating oil leaks, sufficient dynamic pressure will not be generated in the fluid dynamic bearing device, and contact between the inner peripheral surface of the shaft and the outer peripheral surface of the bearing will increase, causing vibration and damage to the contact surface. There is a problem that burn-in occurs.

Japanese Patent Application Laid-Open No. 2020-3046

An object of a bearing member according to an embodiment of the present disclosure is to provide a bearing member that suppresses leakage of lubricating oil.

A bearing member according to an embodiment of the present disclosure includes an inner peripheral surface facing an outer peripheral surface of a shaft with a gap therebetween, holds lubricating fluid in the gap, and supports the shaft so as to be relatively rotatable in a predetermined rotation direction. At least one end of the inner peripheral surface of the bearing member is open to an end face in the axial direction of the bearing member, and the end face and the inner peripheral surface are connected to the inner peripheral surface and form a first slope that increases in diameter toward the end face. a stepped portion connected to the first inclined portion and having a plane orthogonal to the axial direction; and a second inclined portion connected to the stepped portion and the end surface and having a diameter increasing toward the end surface. . The angle formed by the step portion and the second inclined portion is preferably 135° or more and less than 180°. Moreover, it is preferable that the first inclined portion has an R-chamfered portion having a curved surface. Furthermore, the inner peripheral surface may include a dynamic pressure generating portion having an inclined groove inclined with respect to the circumferential direction, and the inclined groove may open to the first inclined portion. A groove connected to the inclined groove may be formed on the surface of the first inclined portion.

According to the bearing member according to the embodiment of the present disclosure, leakage of lubricating fluid can be suppressed.

1 is a perspective view of a bearing member according to one embodiment of the present disclosure; FIG. FIG. 4 is a cross-sectional view when a shaft is inserted into a bearing member according to an embodiment of the present disclosure; FIG. 2B is an enlarged cross-sectional view of the FIG. 2A portion when the shaft is inserted into the bearing member according to the embodiment of the present disclosure; FIG. 2 is a cross-sectional view taken along line AA of FIG. 1;

A bearing member according to the present invention will be described below with reference to the drawings. However, it should be noted that the technical scope of the present invention is not limited to those embodiments, but extends to the invention described in the claims and equivalents thereof.

FIG. 1 shows a perspective view of a bearing member 10 according to one embodiment of the present disclosure. FIG. 2 shows a cross-sectional view when the shaft 20 is inserted into the bearing member 10 according to one embodiment of the present disclosure. FIG. 3 shows a partially enlarged view of part A of the cross-sectional view when the shaft 20 is inserted into the bearing member 10 according to one embodiment of the present disclosure. FIG. 4 shows a cross-sectional view taken along line AA of FIG. In FIG. 4, since the inner peripheral surface 11 is curved, the first dynamic pressure generating portion 17 and the second dynamic pressure generating portion 18 actually appear distorted, but the distortion is omitted for convenience.

A bearing member (hereinafter also simply referred to as “bearing”) 10 is a cylindrical member having a hollow portion 16 , and an inner peripheral surface 11 forming the hollow portion 16 and an inner peripheral surface 11 at the open end of the hollow portion 16 . and an end face 15 connected to the . In the bearing device, a shaft 20 is inserted into a hollow portion 16 of a bearing 10, an outer peripheral surface 21 of the shaft 20 faces an inner peripheral surface 11 of the bearing 10 with a gap d therebetween, and a lubricating fluid 30 is introduced into the gap d. Hold. The bearing device can be of an open type in which the lower portion in the axial direction of the bearing 10 (in the axial direction of the shaft 20) is sealed and the upper portion is open to the outside. Freely support. The bearing device can now rotate the shaft 20 and fix the bearing 10 . However, it is not limited to such an example, and the shaft 20 may be fixed and the bearing 10 may be rotated.

As the lubricating fluid 30, for example, a poly-α-olefin-based synthetic lubricating oil or an ester-based synthetic lubricating oil can be used, but it is not limited to such examples, and other lubricating oils may be used. .

The inner peripheral surface 11 and the end surface 15 of the bearing 10 are connected via a first inclined portion 13, a stepped portion 12 and a second inclined portion 14 which are formed in order from the end portion of the inner peripheral surface 11 toward the end surface 15 side. be done. The first inclined portion 13 is formed along the circumferential direction of the inner peripheral surface 11 , one end of which is connected to the inner peripheral surface 11 , and a portion having a curved surface whose diameter increases from the inner peripheral surface 11 toward the end surface 15 . be. Further, the other end of the first inclined portion 13 is connected to the step portion 12, and the curvature surface of the first inclined portion 13 is a rounded chamfered portion between the inner peripheral surface 11 and the step portion 12. . The step portion 12 has one end connected to the first inclined portion 13 , a portion having a plane orthogonal to the axial direction of the bearing 10 over the circumferential direction, and the other end connected to the second inclined portion 14 . The second inclined portion 14 has one end connected to the step portion 12 and is a portion whose diameter increases from the connection portion with the step portion 12 toward the end surface 15 in the circumferential direction, and the other end is connected to the end surface 15. .

In addition, on the inner peripheral surface 11 of the bearing 10, a first dynamic pressure generating portion 17 and a second dynamic pressure generating portion 18 for generating dynamic pressure on the shaft 20, a first dynamic pressure generating portion 17 and a second dynamic pressure generating portion A band-shaped groove portion 19 arranged between the pressure generating portion 18 is formed. The first dynamic pressure generating portion 17 and the second dynamic pressure generating portion 18 each include dynamic pressure grooves 51 on the surface of the inner peripheral surface 11 , and the dynamic pressure grooves 51 form the first dynamic pressure generating portion 17 and the second dynamic pressure generating portion 17 . A plurality of grooves are formed in each of the portions 18 in the circumferential direction. The dynamic pressure generating grooves 51 are bent, that is, substantially dogleg-shaped grooves with vertices, so-called herringbone-shaped grooves, which are inclined with respect to the circumferential direction of the inner peripheral surface 11 . One end of the dynamic pressure generating groove 51 in the axial direction is connected to the band-shaped groove 19 , and the other end is connected to the first inclined portion 13 while being opened. However, the dynamic pressure generating grooves 51 are not limited to the curved shape, and may be, for example, inclined grooves that are inclined at a predetermined angle with respect to the circumferential direction and do not have vertices.

When the shaft 20 and the bearing 10 rotate relative to each other, it is interposed between the inner peripheral surface 11 of the bearing 10 and the outer peripheral surface 21 of the shaft 20 by the first dynamic pressure generating portion 17 and the second dynamic pressure generating portion 18. The lubricating fluid 30 flows into the dynamic pressure grooves 51 to generate dynamic pressure, and the bearing 10 can radially support the shaft 20 . Further, since the hydrodynamic groove 51 is opened and connected to the first inclined portion 13 , the lubricating fluid 30 can be effectively supplied to the hydrodynamic groove 51 from the end surface 15 side.

The band-shaped groove portion 19 is an annular groove formed along the circumferential direction of the inner peripheral surface 11 . The band-shaped groove portion 19 is connected to dynamic pressure grooves 51 formed in the first dynamic pressure generating portion 17 and the second dynamic pressure generating portion 18 to supply the lubricating fluid 30 .

The bearing 10 can be made of ceramic, for example. Further, when the bearing 10 is made of ceramic, grooves can be formed in the inner peripheral surface 11 of the bearing 10 by providing a projection on the core and pressing the ceramic against the projection. Further, after sintering the formed bearing member, grooves may be formed in the inner peripheral surface 11 by means of cutting, laser processing, or the like.

A bearing member 10 according to an embodiment of the present disclosure includes a first inclined portion 13 , a stepped portion 12 and a second inclined portion 14 between an inner peripheral surface 11 and an end surface 15 of the bearing 10 . When the lubricating fluid 30 intervening between the bearing 10 and the shaft 20 leaks from the gap d, the lubricating fluid 30 flows to the step portion 12 via the first inclined portion 13, but leaks out to the step portion 12. At one end, the lubricating fluid 30 flows (wets and spreads) over the step portion 12 in the circumferential direction. After the lubricating fluid 30 leaks out from the gap d, if the gap d is not filled with the lubricating fluid 30, the gap d is so small that the lubricating fluid 30 returns (flows into) the gap d by capillary action. Further, even if the amount of the lubricating fluid 30 leaking from the gap d is large and reaches the second inclined portion 14 , the surface tension of the lubricating fluid 30 causes the lubricating fluid 30 to move between the stepped portion 12 and the second inclined portion 14 . , and does not immediately flow out of the bearing 10 along the surface of the second inclined portion 14 . In the bearing 10, the stepped portion 12 is a plane perpendicular to the axial direction, and the second inclined portion 14 is formed by a surface whose diameter increases from the stepped portion 12 toward the end surface 15. 10 and the shaft 20 in order to retain the lubricating fluid 30 leaking in the space. The angle θ formed with the inclined portion 14 is 135°. The angle θ between the step portion 12 and the second inclined portion 14 is determined by the size of the bearing 10, specifically, the axial length and the axial length of the inner peripheral surface 11. However, it is preferably 135° or more and less than 180°. As described above, in the bearing member 10 according to the embodiment of the present disclosure, it is possible to suppress the leakage of the lubricating fluid 30 to the outside of the bearing 10, suppress the occurrence of vibration and seizure of the bearing device due to the leakage of the lubricating fluid 30, It becomes possible to maintain the relative rotation between the bearing 10 and the shaft 20 smoothly.

In the above description, an example in which the cross-sectional shape of the first inclined portion 13 is R-chamfered is shown, but the cross-sectional shape is not limited to such an example, and may be C-chamfered. Also, the cross-sectional shape of the second inclined portion 14 is not limited to a linear inclination, and may be an inclination with a curved curvature. Alternatively, a groove connected to the opening of the hydrodynamic groove 51 may be formed on the surface of the first inclined portion 13 . In this case, it is possible to more effectively supply the lubricating fluid 30 to the dynamic pressure grooves 51 from the end surface 15 side.

Further, in the above description, an example in which the inner peripheral surface 11 of the bearing 10 is provided with the first dynamic pressure generating portion 17, the second dynamic pressure generating portion 18, and the strip-shaped groove portion 19 is shown. However, any one or all of the first dynamic pressure generating section 17, the second dynamic pressure generating section 18, and the band-shaped groove section 19 may be omitted, or the number thereof may be further increased. good too.

REFERENCE SIGNS LIST 10 bearing 11 inner peripheral surface 12 stepped portion 13 first inclined portion 14 second inclined portion 15 end surface 16 hollow portion 17 first dynamic pressure generating portion 18 second dynamic pressure generating portion 19 band-like groove portion 20 shaft 21 outer peripheral surface 30 lubricating fluid 51 hydrodynamic groove

Claims (6)

A bearing member comprising an inner peripheral surface facing an outer peripheral surface of a shaft with a gap therebetween, holding a lubricating fluid in the gap, and supporting the shaft so as to be relatively rotatable in a predetermined rotation direction,
At least one end of the inner peripheral surface is open to an axial end surface of the bearing member,
The end surface and the inner peripheral surface have a first inclined portion connected to the inner peripheral surface and increasing in diameter toward the end surface, and a plane connected to the first inclined portion and perpendicular to the axial direction. and a second inclined portion connected to the stepped portion and the end surface and having a diameter increasing toward the end surface. 2. The bearing member according to claim 1, wherein an angle formed by said step portion and said second inclined portion is 135[deg.] or more and less than 180[deg.]. 2. The bearing member according to claim 1, wherein the first inclined portion has an R-chamfered portion with a curved surface. 2. The bearing member according to claim 1, wherein the inner peripheral surface includes a dynamic pressure generating portion having an inclined groove inclined with respect to the circumferential direction of the inner peripheral surface. 5. The bearing member according to claim 4, wherein the inclined groove opens to the first inclined portion. 6. The bearing member according to claim 5, wherein a groove connected to said inclined groove is formed on the surface of said first inclined portion.

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