JP2002155940A - Dynamic pressure bearing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a dynamic pressure bearing device eliminating torque increase due to enlargement of a flange diameter of a shaft and preventing leakage of lubricating fluid to the outside. SOLUTION: In this dynamic pressure bearing device provided with a relatively rotating housing 1 and the shaft 3 rotating inside a through-hole 2 of the housing 1, the lubricating fluid 6 is sealed between the housing 1 and the shaft 3, a flange 4 of the shaft 3 is fit in an annular recessed part 5 of an inner diameter face of the housing 1, and thrust dynamic pressure generating parts B1 and B2 are provided between the annular recessed part and upper and lower faces of the flange 4. It is characterized by that a communication passage 11 opened to a bottom part 5c of the annular recessed part 5 from the through- hole 2 of the housing 1 is formed in a housing 1 portion on a flange upper face 4a side of the shaft 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a dynamic bearing device.

[0002]

2. Description of the Related Art Conventionally, a dynamic pressure bearing device shown in FIG. 4 is known. This dynamic pressure bearing device includes a housing 41 and a rotating shaft 43 inserted through a predetermined gap so as to be rotatable relative to an axial through hole 42 of the housing 41, and a shaft end portion remains on the rotating shaft 43. The flange 44 formed as described above is fitted with a predetermined gap into an annular concave portion 45 formed in the inner surface of the through hole 42 of the housing 41, and the upper surface 44a of the flange 44 (the upper surface in FIG. 4), the through hole 42 of the housing 41 is opened 47 to the outside, a lubricating fluid 46 is sealed between the housing 41 and the rotating shaft 43, and the upper surface 44a and the lower surface 44b of the flange (the lower surface in FIG. And the upper and lower flange surfaces 4 of the annular recess 45.
Thrust dynamic pressure generating portions B1 and B2 are provided between surfaces 45a and 45b opposed to 4a and 44b. The opening 47 between the housing 41 and the rotating shaft 43 is
The labyrinth is sealed. The thrust dynamic pressure generating portions B1 and B2 are formed by forming dynamic pressure generating grooves 48 and 49 on the upper surface 44a and the lower surface 44b of the flange 44, respectively.
8, 49 may be formed on the inner surface 45a, 45b side of the annular concave portion. A dynamic pressure generating groove 50 is formed in the rotating shaft 43 on the flange lower surface 44b side, and a radial dynamic pressure generating portion B3 is formed between the rotating shaft 43 and the housing 41. The dynamic pressure generating groove 50 of the radial dynamic pressure generating portion B3 may be formed on the inner surface of the through hole 42 of the housing 41 in some cases.

Further, a flange upper surface 44a of the rotary shaft 43 is provided.
The through hole 42 of the housing 41 on the side is open to the outside 4
7, the rotation of the rotating shaft 43 is repeatedly started and stopped, and the rotation of the rotating shaft 43 is repeated.
Opening portion 47 at the upper part of 2 (on the upper surface 44a side of the flange 44)
The lubricating fluid 46 moves to the side, and the lubricating fluid 46 may leak from the open portion 47 that seals the labyrinth.
It is necessary to prevent the movement of the lubricating fluid 46 to the air. Therefore, an axial through hole 5 parallel to the axis passing through the flange upper and lower surfaces 44a and 44b is formed at the base of the flange 44 of the rotating shaft 43.
1 is formed for circulation of the lubricating fluid 46.

[0004]

In the conventional hydrodynamic bearing device, the lubricating fluid is applied to the flange 44 without reducing the load capacity of the thrust dynamic pressure generating portions B1 and B2 formed on the flange 44 of the rotating shaft 43. Since it is necessary to form the axial through hole 51 for preventing the leakage of the outside of the flange 46, the diameter of the flange 44 becomes large and the torque becomes large.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a hydrodynamic bearing device that eliminates an increase in torque due to an increase in the flange diameter of a shaft and that prevents leakage of lubricating fluid to the outside.

[0006]

Means for Solving the Problems As means for solving the above problems, the invention of claim 1 comprises a housing which rotates relatively and a shaft which is inserted through an axial through hole of the housing with a predetermined gap. A flange formed so that a shaft end portion remains on the shaft is fitted with a predetermined gap into an annular concave portion formed on the inner surface of the through hole of the housing, and a through hole of the housing on the upper surface side of the flange is provided. Is open to the outside, a lubricating fluid is sealed between the housing and the shaft, and a dynamic pressure generating portion is provided between the upper and lower surfaces of the flange and the surface of the annular concave portion facing the upper and lower surfaces of the flange. In the bearing device, a communication passage is formed in the housing portion facing the upper surface side of the flange of the shaft, the communication passage opening from the inner surface of the through hole of the housing to the bottom of the annular concave portion. .

According to a second aspect of the present invention, the housing is formed by integrating an upper split housing and a lower split housing which are axially split at the annular concave position on the upper surface of the shaft flange. It is characterized by the following.

Further, in the invention of claim 3,
The communication passage is formed in a radial hole formed on an outer diameter portion side from an inner diameter surface of the through hole of the upper split housing, and intersects with the radial hole formed in an outer diameter portion of the upper split housing and is formed in a bottom portion of the annular concave portion. And a cutout portion that is open to the outside.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a specific embodiment of the present invention will be described with reference to FIG. The hydrodynamic bearing device includes a housing 1 and a rotating shaft 3 inserted through a predetermined gap so as to be rotatable relative to an axial through hole 2 of the housing 1, and a shaft end portion remains on the rotating shaft 3. The flange 4 formed as described above is fitted with a predetermined gap into an annular concave portion 5 formed on the inner surface of the through hole 2 of the housing 1, and the upper surface 4 a of the flange 4 (the upper surface in FIG. 1 is referred to as the upper surface). ) Side housing 1 through hole 2
Is open to the outside 7, lubricating fluid 6 is sealed between the housing 1 and the rotating shaft 3, and the upper surface 4 a and the lower surface 4 b of the flange 4 (the lower surface in FIG. Thrust dynamic pressure generating portions B1 and B2 are provided between the upper and lower surfaces 5a and 5b facing the upper and lower flange surfaces 4a and 4b. The opening 7 between the housing 1 and the rotating shaft 3 is labyrinth-sealed. The thrust dynamic pressure generating portions B1, B2 are provided on the upper surface 4 of the flange 4.
a and the lower surface 4b are formed with dynamic pressure generating grooves 8 and 9, respectively. However, if necessary, the dynamic pressure generating grooves 8 and 9 may be formed on the inner surfaces 5a and 5b of the annular concave portions. A dynamic pressure generating groove 10 is formed on the rotating shaft 3 on the flange lower surface 4 b side, and a radial dynamic pressure generating portion B 3 is formed between the rotating shaft 3 and the housing 1. The dynamic pressure generating groove 10 of the radial dynamic pressure generating portion B3 may be formed on the inner surface of the through hole 2 of the housing 1.

The upper housing 1a and the lower housing 1b, which are axially divided at the flange upper surface 4a of the rotary shaft 3 and at the position of the annular recess 5, are formed by press-fitting or bonding. It is formed integrally. A large-diameter step 12 is formed on the inner surface of the through hole 2 of the upper split housing 1a on the flange 4 side, and a communication passage 11 is formed from the step 12 to the bottom 5c of the annular recess 5. ing. This communication path 11
As can be better understood in FIG. 2, at two positions 180 degrees opposite to each other with respect to the upper split housing 1a, a radial hole 11a formed on the outer diameter side from the inner diameter surface of the through hole 2 of the upper split housing 1a. And a cut-out portion 11b formed in the outer diameter portion of the upper split housing 1a and intersecting with the radial hole 11a and opening into the bottom 5c of the annular concave portion 5. The cut portion 11b also functions as a lubricating fluid reservoir, and helps prevent running out of the lubricating fluid. In the configuration shown in FIG. 2, the cut-out portion 11b is formed by being cut linearly in the tangential direction of the outer diameter surface of the upper split housing 1a. This structure is advantageous in that when the size of the bearing is small, it is easy to secure the volume as the oil reservoir and the processing is easy. FIG. 3 shows another embodiment of the cut portion, and the cut portion 11b is cut in the upper split housing 1a by an arc having a center on the outer diameter surface side. This structure is advantageous in the case of a relatively large bearing size from the viewpoint of securing the volume of the oil reservoir, and is advantageous in that machining is facilitated. Although the radial hole of the communication passage 11 is formed directly in the upper housing 1a by a drill or the like, a radial groove is formed on the lower surface of the upper housing 1a, and the upper housing 1a is formed so as to cover the radial groove. A separate lid may be integrated with the inner surface of 1a to form a substantially radial hole 11a.

In the embodiment shown in FIG. 1, the housing 1 is divided into an upper divided housing 1a and a lower divided housing 1b.
However, the working of the communication path 11 is greatly facilitated.

Next, the operation of the communication passage 11 will be described. Although the bearing clearance of the thrust dynamic pressure generating portions B1 and B2 which varies with the start and stop of the rotary shaft 3 changes, the clearance between the flange upper surface 4a of the rotary shaft 3 and the inner surface of the recess 5 of the housing 1, that is, the upper thrust dynamic pressure When the bearing clearance of the generating portion B1 is reduced, the lubricating fluid 6 near the outer diameter side of the upper thrust dynamic pressure generating portion B1 and near the cutout portion 11b of the communication passage 11 is drawn into the flange lower surface 4b side. As a result, the housing 1 on the upper surface 4a side of the flange 4
The lubricating fluid 6 in the through hole 2 is received by the step portion 12 and efficiently drawn into the communication passage 11 to move smoothly to the lower surface 4b side of the flange 4 where the bearing clearance becomes large, thereby allowing the housing 1 to penetrate. The lubricating fluid 6 near the external opening 7 of the hole 2 is prevented from being pushed out and leaking.

In the above embodiment, the case where the shaft 3 rotates is shown. However, the housing 1 may rotate while the shaft 3 is fixed.

[0014]

As described above, according to the first to third aspects of the present invention, since the axial flange has no axial through hole penetrating the upper and lower surfaces, the thrust and the load capacity of the dynamic pressure generating portion are maintained. The flange diameter can be reduced, and the torque can be reduced. Further, since the lubricating fluid smoothly circulates when the bearing clearance of the thrust dynamic pressure generating portion is reduced by the communication passage formed in the housing, leakage of the through hole of the housing from the externally opened portion is prevented.

[Brief description of the drawings]

FIG. 1 is a sectional view of a hydrodynamic bearing device according to an embodiment of the present invention.

FIG. 2 is a plan view of the flange shown in FIG. 1 as viewed from above, and is an embodiment of the communication passage of the present invention.

FIG. 3 is a plan view of the communication passage according to another embodiment of the present invention, as viewed from above the flange of FIG. 1;

FIG. 4 is a sectional view of a conventional hydrodynamic bearing device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Housing 1a Upper divided housing 1b Lower divided housing 2 Through-hole 3 Rotating shaft 4 Flange 5 Annular recess 6 Lubricating fluid 7 Opening part 8 Dynamic pressure generating groove 9 Dynamic pressure generating groove 10 Dynamic pressure generating groove 11 Communication path 11a Radial hole 11b Resection

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Yasuo Takamura 3-5-8 Minamisenba, Chuo-ku, Osaka-shi Koyo Seiko Co., Ltd. F-term (reference) 3J011 AA07 BA06 BA09 CA01 CA02 JA02 KA02 KA03 MA04 MA23

Claims (3)

[Claims] 1. A housing having a relatively rotating housing and a shaft inserted through a through hole in the axial direction of the housing with a predetermined gap therebetween, and a flange formed so that a shaft end portion remains on the shaft has an inner diameter of the through hole of the housing. A predetermined gap is inserted into an annular concave portion formed on the surface, a through hole of the housing on the upper surface side of the flange is opened to the outside, lubricating fluid is sealed between the housing and the shaft, and the flange is closed. In a hydrodynamic bearing device in which a thrust dynamic pressure generating portion is provided between upper and lower surfaces and a surface of the annular concave portion opposed to the upper and lower surfaces of the flange, a housing penetrates the housing portion facing the flange upper surface side of the shaft. A hydrodynamic bearing device, wherein a communication passage opening from the inner diameter surface of the hole to the bottom of the annular concave portion is formed. 2. The housing according to claim 1, wherein an upper split housing and a lower split housing which are axially split at an annular recess position on an upper surface side of a shaft flange are integrally formed. 2. The dynamic pressure bearing device according to 1. 3. The communication passage intersects a radial hole formed on an outer diameter portion side from an inner diameter surface of the through hole of the upper split housing, and a radial hole formed on an outer diameter portion of the upper split housing, and 3. The hydrodynamic bearing device according to claim 2, wherein the hydrodynamic bearing device is formed of a cut-out portion that opens into the bottom of the annular concave portion.