JP2003301835A - Hydrodynamic bearing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hydrodynamic bearing capable of improving an adhesion force between a cover member (thrust plate) and a bearing sleeve, and preventing the seepage of an adhesive to a sealed space in the bearing sleeve. <P>SOLUTION: A annular recess 21 communicated with a space S between the inner circumferential surface 13y of a circumferential step 13s and the outer circumferential surface 14y of the cover member 14 is formed in at least one of the junction surface 13x of the bearing sleeve 13 and the junction surface 14x of the cover member 14. In this constitution, the adhesive 30 can be filled even in a diametrical space (the annular recess 21) formed in the junction surfaces. This hydrodynamic bearing is thus capable of preventing the lubricating fluid enclosed in the sealed space 31 in the bearing from leaking outward. By forming a circular groove 22 as a sump part for the adhesive 30 in the junction surface 13x on the inner side of the annular recess 21 in a diametral direction, the seepage of the adhesive 30 to the sealed space in the bearing can be prevented. <P>COPYRIGHT: (C)2004,JPO

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 used for a spindle motor of a hard disk drive,
More specifically, the present invention relates to a dynamic pressure bearing capable of preventing leakage of a lubricating fluid sealed inside the bearing.

[0002]

2. Description of the Related Art In recent years, along with the widespread use of OA equipment in offices and homes, it has been required to reduce the noise of these OA equipment. Therefore, in a hard disk drive used in a personal computer, a conventional spindle motor that uses a rolling bearing cannot satisfy the quietness and high-speed / high-precision rotation, and instead, a dynamic pressure bearing (or a fluid bearing). Spindle motors using are beginning to be adopted. The dynamic pressure bearing used in such a motor is
A lubricating fluid is sealed between a shaft and a bearing (housing) arranged around the shaft with a predetermined distance, and the relative rotation of these fluids causes the movement formed on the shaft or the surface of the bearing. The shaft and the bearing are kept in non-contact with each other by the dynamic pressure generated in the pressure groove.

FIG. 8 is a schematic sectional view showing the structure of a conventional dynamic pressure bearing, and FIG. 9 shows a method of forming a bearing housing as an enlarged view of an R portion in FIG. The dynamic pressure bearing 51 includes a shaft 1 including a shaft body 11 and a flange portion 12 provided at one end of the shaft body 11, and these shaft bodies 11.
And a housing 2 for accommodating the flange portion 12 in a sealed state. V-shaped or herringbone-shaped dynamic pressure grooves 11a, 11a for generating radial dynamic pressure are formed on the surface of the shaft body 11, and the herringbone for generating thrust dynamic pressure is formed on both end surfaces of the flange portion 12. Shape or V
Dynamic pressure grooves 12a, 12a having a character shape are formed.

The housing 2 is a substantially cylindrical bearing sleeve 1.
3 and a lid member 14 that seals one opening of the bearing sleeve 13. This bearing sleeve 13
A circumferential stepped portion 13s having an inner diameter larger than the outer diameter of the lid member 14 is formed at the closed end (upper side in the drawing) side of the lid member 14, and the lid member 14 is fitted to the inner circumference of the circumferential stepped portion 13s.
The lid member 14 functions as a thrust plate that receives the dynamic pressure generated in the thrust dynamic pressure groove 12a. In the dynamic pressure bearing 51, the lid member 14 is joined and fixed to the circumferential step portion 13s of the bearing sleeve 13 by an adhesive agent 30 described later, and a closed space (31) formed between the shaft 1 and the housing 2 is provided. ) Is filled with the lubricating fluid 32 for generating the dynamic pressure and used.

In such a dynamic pressure bearing, the method of fixing the lid member (or thrust plate) of the bearing housing is
Contributes significantly to bearing dimensions and performance. However, when the lid member is fixed by press fitting or the use of screws, the radial dimension of the entire bearing becomes large, and the deformation (distortion) of the bearing sleeve may affect the rotation accuracy.
Therefore, the method of integrating the bearing sleeve and the lid member is
As described above, a method of fitting the lid member into the bearing sleeve with a clearance fit and joining and fixing with an adhesive or the like is often used.

The joint fixing of the bearing sleeve 13 and the lid member 14 is carried out by inserting the shaft 1 into the bearing sleeve 13 as shown in FIG.
With the lid member 14 fitted to 3s, the joint surface 14x of the lid member 14 is fixed to the circumferential step portion 13 by using a jig or the like (not shown).
The inner peripheral surface 13y of the circumferential stepped portion 13s and the outer peripheral surface 1 of the lid member 14 while closely adhering to the joint surface (matching surface) 13x of s.
It is performed by pouring the adhesive 30 into the annular gap S formed between 4y.

The adhesive 30 is poured in a predetermined amount between the open end of the bearing sleeve 13 and the tapered portions 13z, 14z provided on the outer peripheral surface 14y of the lid member 14, respectively. Then, the adhesive 30 permeates to the bottom of the gap S due to its own weight or a capillary phenomenon with time, and integrates the bearing sleeve 13 and the lid member 14. A thermosetting adhesive made of epoxy resin or the like is preferably used as the type of the adhesive 30.

[0008]

However, in the above dynamic pressure bearing, there is a problem that the lubricating fluid sealed inside the bearing leaks to the outside. It is considered that such a leakage of the lubricating fluid is caused by the looseness of the fixing of the lid member due to the pressure variation of the lubricating fluid due to the operation of the dynamic pressure bearing and the vibration of the entire apparatus.

In order to solve this problem, in order to increase the adhesion of the lid member, the gap between the circumferential step portion of the bearing sleeve, which is the filling portion of the adhesive, and the lid member is widened in the radial direction, or There is a method of extending in the axial direction. However, in the method of widening the gap in the radial direction, the amount of the adhesive used increases, and there is a concern that the adhesive may be uncured or may leak into the bearing internal space. Further, the method of extending the gap in the axial direction increases the size of the entire dynamic pressure bearing device, which has many size restrictions as parts.

On the other hand, as another problem, there is also a problem that the adhesive used for joining and fixing leaks into the sealed space inside the bearing sleeve. Normally, the bonding between the bearing sleeve and the lid member is performed in a state in which these joint surfaces are pressure-bonded to each other, but the surface of the bearing sleeve and the lid member may have fine unevenness during shape processing, Due to the capillary phenomenon or the like, the adhesive penetrates into the minute gaps.

In addition, the viscosity of an adhesive generally changes drastically with temperature, and the wettability on the surface also greatly changes depending on the material to which it is applied. In addition, in the case of a two-component adhesive having a high adhesive force, there is a change with time in the viscosity after the two-component kneading.
Therefore, it is difficult to control the penetration of the adhesive from the type and composition of the adhesive.

The present invention has been made in view of the above circumstances, and improves the adhesion between the lid member (thrust plate) and the bearing sleeve and allows the adhesive to seep into the sealed space inside the bearing sleeve. It is an object of the present invention to provide a dynamic pressure bearing capable of preventing the above.

[0013]

In order to achieve the above object, the invention according to claim 1 seals a shaft, a bearing sleeve disposed around the shaft, and an opening of the bearing sleeve. A lid member, and a circumferential step portion into which the lid member can be fitted is formed in one opening of the bearing sleeve, and an end surface of the circumferential step portion and an end surface of the lid member. In a gap between the inner peripheral surface of the circumferential step portion and the outer peripheral surface of the lid member filled with an adhesive, the bearing sleeve and the lid member An annular recess is formed at the outer peripheral edge of the joining surface in the radial direction so as to communicate with the gap and extend the portion filled with the adhesive toward the inner side in the radial direction.

According to the second aspect of the present invention, in addition to the annular recess, the adhesive is prevented from penetrating into a region of the joint surface between the bearing sleeve and the lid member, which is radially inward of the annular recess. It is characterized in that a circumferential groove serving as a reservoir is provided.

According to the present invention, in a dynamic pressure bearing in which a bearing housing composed of a bearing sleeve and a lid member is integrated by using an adhesive, the adhesive used is a bonding surface between the bearing sleeve and the lid member. It is intended to achieve the intended purpose by guiding only to a specific part useful for improving the fixing force of the lid member in the above.

That is, in the invention according to claim 1, the radial outer edge portion of the joint surface on the bearing sleeve side and the joint surface on the lid member side are formed so as to communicate with the gap formed between the bearing sleeve and the lid member. At least one of the radially outer edge portions is formed with an annular recess serving as an adhesive filling portion.
With this configuration, not only the axial space formed between the circumferential step portion and the lid member, but also the radial space formed at the joint surface between the circumferential step portion and the lid member is filled with the adhesive. The adhesion force (fixing force) of the lid member can be improved. In other words, by introducing the adhesive to the joint surface between the bearing sleeve and the lid member, the lid member, which was fixed only by the adhesive force in the shearing direction of the adhesive, is made stronger by the adhesive force in the pulling direction of the adhesive. It becomes possible to fix it by using it.

The invention according to claim 2 is intended to prevent the adhesive from penetrating into a sealed space inside the bearing due to a capillary phenomenon or the like, and the bonding surface is radially inward of the annular recess. , Forming a groove in the circumferential direction that serves as a reservoir for the adhesive. With this configuration, even if a minute gap is left on the joint surface of the bearing sleeve or the lid member during the shape processing, the permeation of the adhesive due to the capillary phenomenon or the like is stopped by the circumferential groove. Therefore, the dynamic pressure bearing of the present invention can prevent the adhesive from leaching into the sealed space inside the bearing.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic cross-sectional view showing the structure of a dynamic pressure bearing according to the first embodiment of the present invention, and FIG. 2 shows a method of forming a bearing housing as an enlarged view of a portion P in FIG. . In addition, FIG. 3 is an enlarged perspective view showing the structure of the bearing sleeve in the first embodiment. In addition, the same code | symbol is attached | subjected to the structural member which has the same function as a conventional example.

The dynamic pressure bearing 41 in this embodiment also has the same basic structure as the conventional example. This dynamic pressure bearing 41 is
The shaft 1 is composed of a shaft 11 and a flange portion 12 provided at one end of the shaft body 11, and a housing 2 for accommodating the shaft body 11 and the flange portion 12 in a sealed state. On the surface of the shaft body 11, a dynamic pressure groove 11a of V-shape or herringbone shape for generating radial dynamic pressure,
11a is formed, and dynamic pressure grooves 12a, 12a having a herringbone shape or a V shape for generating thrust dynamic pressure are formed on both end surfaces of the flange portion 12.

The housing 2 has a substantially cylindrical bearing sleeve 1.
3 and a lid member 14 that seals one opening of the bearing sleeve 13. This bearing sleeve 13
A circumferential stepped portion 13s having an inner diameter larger than the outer diameter of the lid member 14 is formed at the closed end (upper side in the drawing) side of the lid member 14, and the lid member 14 is fitted to the inner circumference of the circumferential stepped portion 13s.
The lid member 14 functions as a thrust plate that receives the dynamic pressure generated in the thrust dynamic pressure groove 12a. In this dynamic pressure bearing 41 as well, the lid member 14 is joined and fixed to the circumferential step portion 13s of the bearing sleeve 13 by the adhesive agent 30 described later, and the closed space (31) formed between the shaft 1 and the housing 2 is used. ) Is filled with the lubricating fluid 32 for generating the dynamic pressure and used.

Further, as in the conventional example, the joint fixing of the bearing sleeve 13 and the lid member 14 is carried out by inserting the shaft 1 into the bearing sleeve 13 as shown in FIG. With the lid member 14 fitted to the portion 13s, the joint surface 14x of the lid member 14 is brought into close contact with the joint surface 13x of the circumferential step portion 13s by using a jig or the like (not shown), and the circumferential step portion 13s is Inner peripheral surface 13y and lid member 14
It is performed by pouring the adhesive 30 into the annular gap S formed between the outer peripheral surfaces 14y. Note that the adhesive 30
As the type of, a thermosetting adhesive made of an epoxy resin or the like is preferably used.

The characteristic feature of the dynamic pressure bearing 41 in this embodiment is that, as shown in FIG.
The point is that an annular concave portion 21 is formed at the outer edge of x to extend a portion filled with the adhesive in the radial direction. As shown in FIG. 2, when the adhesive 30 used is injected in a predetermined amount between the opening end of the bearing sleeve 13 and the tapered portions 13z and 14z provided on the outer peripheral surface 14y of the lid member 14, the adhesive 30 is bonded. Not only the gap S in the axial direction but also the space (annular recess 21) in the radial direction communicating with the gap S is filled by the self-weight of the agent 30 itself or a capillary phenomenon. That is, the adhesive 3
By guiding 0 to the annular recess 21, the lid member 14, which was conventionally fixed only by the axial shear adhesive force of the adhesive 30, is fixed by using a stronger tensile adhesive force in the axial direction. Will be possible.

Further, the extended adhesive filling portion is
The effect of ensuring the sealing of the lubricating fluid filled in the sealed space inside the bearing can also be achieved. Therefore, in the dynamic pressure bearing 41 according to the present embodiment, the adhesion force (fixing force) of the lid member 14 can be improved and the lubricating fluid 32 can be prevented from leaking to the outside.

Next, a second embodiment of the present invention will be described. FIG. 4 is a schematic cross-sectional view showing the structure of the dynamic pressure bearing according to the second embodiment of the invention, and FIG. 5 shows a method of forming the bearing housing as an enlarged view of a Q portion of FIG. . The dynamic pressure bearing 42 in the present embodiment also has the same basic structure as in the first embodiment.

Further, the joint fixing of the bearing sleeve 13 and the lid member 14 is the same as in the first embodiment.
The shaft 1 is inserted into the inside of this bearing sleeve 13
With the lid member 14 fitted to the circumferential step portion 13s of
Using a jig or the like (not shown), the joint surface 14x of the lid member 14
While closely adhering to the joint surface 13x of the circumferential step portion 13s, the adhesive 30 is applied to the annular gap S formed between the inner peripheral surface 13y of the circumferential step portion 13s and the outer peripheral surface 14y of the lid member 14.
Is carried out by pouring a predetermined amount.

The feature of the dynamic pressure bearing 42 in the present embodiment is that an annular recess 21 is formed at the outer edge of the joint surface 13x of the bearing sleeve 13 to extend the portion filled with the adhesive in the radial direction. This is the point that a circumferential groove (circumferential groove) 22 serving as an adhesive reservoir is formed on the joint surface 13x radially inward of the recess 21. With this configuration, even when fine irregularities are left on the joint surface 13x of the circumferential step portion 13s and the joint surface 14x of the lid member 14 during the shape processing, the permeation of the adhesive agent 30 due to a capillary phenomenon or the like can be stopped. it can.

That is, when there is a minute gap between the joint surfaces 13x and 14x, the capillary phenomenon occurs after the adhesive 30 is filled in the axial gap S and the radial space (annular recess 21). For example, it may be considered that the permeation occurs between the joint surfaces depending on the circumstances. However, in the present embodiment, the permeation of the adhesive 30 is stopped at the circumferential groove 22 (reservoir portion), and the permeation of the adhesive 30 into the area on the inner diameter side of the circumferential groove 22 is prevented. Becomes Therefore, the dynamic pressure bearing 42 of the present invention can prevent the adhesive 30 from leaching into the sealed space 31 inside the bearing.

In the dynamic pressure bearing 42, not only the axial gap S but also the radial space (annular recess 21) communicating with the axial gap S is filled with the adhesive 30 as in the first embodiment. A high fixing force of the lid member 14 can be obtained, and the lubricating fluid 32 can be prevented from leaking to the outside.

In the above embodiment, the sectional shape of the annular recess 21 formed on the joint surface 13x of the bearing sleeve 13 is substantially concave, but the shape of the annular recess of the present invention is not limited to this. Without joining surface 13x as shown in FIG.
It is also possible to provide a taper portion 23 on the outer edge of or to adopt another cross-sectional shape. Further, the position where the annular recess is provided may also be formed on the outer edge of the joint surface 14x on the lid member 14 side, like the annular recess 25 shown in FIG.

Furthermore, the cross-sectional shape of the circumferential groove 22 formed on the inner diameter side of the joining surface 13x is not limited to those of these embodiments, and the cross-section is substantially V-shaped or substantially concave. Alternatively, other cross-sectional shapes can be adopted. A plurality of the circumferential grooves may be formed on the same joint surface,
Similar effects can be obtained by forming the bonding surface 14x on the lid member 14 side like the circumferential groove 24 shown in FIG.

[0031]

As described in detail above, according to the dynamic pressure bearing of the present invention, the inner peripheral surface of the circumferential step portion and the lid member are provided on at least one of the joint surface of the bearing sleeve and the joint surface of the lid member. By forming an annular recess that communicates with the gap formed between the outer peripheral surface and the radial surface, the space in the radial direction formed between these joint surfaces is filled with the adhesive, and the adhesion of the lid member is improved. be able to. Therefore, the dynamic pressure bearing of the present invention can prevent the lubricating fluid sealed in the sealed space inside the bearing from leaking to the outside.

Further, by forming a groove in the circumferential direction, which serves as a reservoir for the adhesive, on the joint surface radially inward of the annular recess, the adhesive is prevented from leaching into the sealed space inside the bearing. be able to.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing a structure of a dynamic pressure bearing according to a first embodiment of the present invention.

FIG. 2 is an enlarged view of a portion P in FIG. 1 showing a method for forming a bearing housing according to the first embodiment of the present invention.

FIG. 3 is a perspective view showing a structure of a bearing sleeve according to the first embodiment of the present invention.

FIG. 4 is a schematic sectional view showing a structure of a dynamic pressure bearing according to a second embodiment of the invention.

FIG. 5 is an enlarged view of a Q portion of FIG. 4 showing a method of forming a bearing housing according to the second embodiment of the present invention.

FIG. 6 is a schematic enlarged view showing the structure of another bearing housing according to the second embodiment of the invention.

FIG. 7 is a schematic enlarged view showing the structure of still another bearing housing according to the second embodiment of the invention.

FIG. 8 is a schematic cross-sectional view showing the structure of a conventional dynamic pressure bearing.

9 is an enlarged view of an R portion in FIG. 8 showing a method of forming a bearing housing in a conventional dynamic pressure bearing.

[Explanation of symbols] 1 shaft 2,3 housing 11 axis 11a Dynamic pressure groove 12 Flange 12a Dynamic pressure groove 13 Bearing sleeve 13s circumferential step 13x joining surface 13y inner surface 13z taper part 14 Lid member 14x joining surface 14y outer peripheral surface 14z taper part 21,23,25 annular recess 22,24 circumferential groove 30 adhesive 31 closed space 32 Lubricating fluid 41,42 Dynamic bearing 51 Dynamic bearing S gap

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Claims (2)

[Claims] 1. A shaft, a bearing sleeve arranged around the shaft, and a lid member for sealing an opening of the bearing sleeve, wherein the lid member is fitted into one opening of the bearing sleeve. A circumferential step portion that can be inserted is formed, and an end surface of the circumferential step portion and an end surface of the lid member are joined together, and an inner peripheral surface of the circumferential step portion and an outer peripheral surface of the lid member are formed. In a dynamic pressure bearing formed by filling an adhesive in a gap formed between, a radial outer edge of a joint surface between the bearing sleeve and the lid member is in communication with the gap and a portion filled with the adhesive in a radial direction. A hydrodynamic bearing, wherein an annular recess extending inward is formed. 2. A circumferential groove serving as a reservoir for preventing the permeation of an adhesive is provided in a region radially inward of the annular recess on a joint surface between the bearing sleeve and the lid member. The dynamic pressure bearing according to claim 1.