JP3004512B2 - Dynamic pressure bearing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydrodynamic bearing device in which a lubricant is sealed.

[0002]

2. Description of the Related Art Conventionally, as a dynamic bearing device of this kind,
As shown in FIG. 6, there is an X-ray dynamic pressure bearing device using a metal lubricant. This device includes a rotating body 60 and a rotating body 6.
And a fixed body 69 disposed inside the rotating body 60, and a space between the rotating body 60 and the fixed body 69 is filled with a metal lubricant (not shown).

The fixed body 69 has a cylindrical head 61 and a neck 65 extending vertically downward from the head 61. The rotating body 60 includes a cylindrical part 62 surrounding the outer periphery of the head 61 and a cylindrical part 62. 62, which is fixed to the lower end of
1 and a flange plate 63 facing the lower surface 61b. A dynamic pressure groove (not shown) is formed on the outer peripheral surface 61a and the bottom surface 61b of the head 61.

In this dynamic pressure bearing device for an X-ray tube, a rotating anode of the X-ray tube is fixed on the rotating body 60, and the rotating body 60
Is rotated with respect to the fixed body 69, the dynamic pressure grooves formed on the outer peripheral surface 61a and the bottom surface 61b of the head 61 generate dynamic pressure on the metal lubricant, and cause the rotating body 60 to move radially and axially. To support.

[0005]

However, in the conventional dynamic pressure bearing for an X-ray tube, the metal lubricant leaks from the gap G between the flange plate 63 of the rotating body 60 and the neck 65 of the fixed body 69. There is a problem that poor lubrication occurs and this poor lubrication leads to a short life.

SUMMARY OF THE INVENTION An object of the present invention is to provide a dynamic pressure bearing device which can prevent leakage of a lubricant, and is particularly preferably used for a dynamic pressure bearing device for an X-ray tube.

[0007]

In order to achieve the above object, a dynamic pressure bearing device for an X-ray tube according to the present invention is provided with a cylindrical outer cylindrical member, and is disposed inside the outer cylindrical member by rotating relative to the outer cylindrical member. An inner peripheral surface of the outer cylinder member radially opposed to the head of the shaft body, the shaft body including a head to be formed and a neck portion extending from the head to the outside of the outer cylinder member in the axial direction. Or a radial support dynamic pressure generating groove is formed on at least one of the outer peripheral surfaces of the head of the shaft radially opposed to the outer cylinder member, and a lubricant is provided between the outer cylinder member and the shaft. In the filled hydrodynamic bearing device, the outer cylinder member has a flange portion located around the neck portion and a lower portion of a head of the shaft body and axially opposed to the shaft portion, and the shaft facing the flange portion. At least an axially facing surface of the head of the body or an axially facing surface of the flange portion facing the axially facing surface of the head; Write and axial support for dynamic pressure generating grooves are formed in the axial direction facing surface of the head of the shaft axially opposite facing surface or the flange portion of the flange portion of the outer tube member,
An axial concave portion surrounding the neck portion is formed, and enters the axial concave portion on an axially facing surface of a head of the shaft body facing the flange portion or an axially facing surface of a flange portion of the outer cylindrical member. It is characterized in that an axial projection is formed.

[0008]

For example, when the outer cylinder member rotates, an axial recess formed in the axially opposed surface of the flange of the outer cylinder member or the axially opposed surface of the head of the shaft body opposed to the flanged portion. Thus, the metal lubricant accumulates. Therefore, it is possible to prevent the metal lubricant from leaking from the gap between the flange of the outer cylinder member and the neck of the fixed body.

Further, since the axial concave portion and the axial convex portion entering the concave portion form a labyrinth space,
The lubricant is held in the labyrinth space. Therefore, it is possible to prevent the lubricant from leaking from the gap between the flange of the outer cylinder member and the neck of the shaft.

Further, when the outer cylinder member rotates, a centrifugal force acts radially outward on the lubricant in the axial recess, so that the lubricant is directed radially outward, and It is possible to prevent the lubricant from leaking from a gap between the flange portion and the neck portion of the radially inner fixed body.

[0011]

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

FIG. 1 shows an embodiment of a hydrodynamic bearing device according to the present invention. This embodiment shows a case where the present invention is particularly applied to a dynamic pressure bearing device for an X-ray tube, and includes a cylindrical rotating body 1 as an outer cylindrical member and a fixed body as a shaft fitted to the rotating body 1. 4 is provided.

The rotating body 1 comprises a lid 1b to which a rotating anode of an X-ray tube is fixed, a cylindrical tubular portion 1c, and a cylindrical portion 1c.
c includes a lower flange portion 2 fixed to the lower end. Further, a shaft-shaped long and thin cooling hole 13 is formed in the center of the fixed body 4. The fixed body 4 includes a cylindrical head 3 disposed inside the rotating body 1 and a neck 5 extending vertically downward from the head 3 to the outside of the rotating body 1.

A plurality of V-shaped dynamic pressure grooves 6 are formed on the outer peripheral surface of the head 3. As shown in FIG. 1B, a plurality of V-shaped dynamic pressure grooves 7 are formed in the circumferential direction on the upper end surface 3a of the head 3 in the axial direction. FIG. 1C shows an axial lower end surface 3b of the lower portion 3c of the head 3.
As shown in the figure, a plurality of V-shaped dynamic pressure grooves 8 are formed in the circumferential direction opposite to the dynamic pressure grooves 7.

The rotating body 1 is adapted to be rotated about a straight line extending in a substantially vertical direction as a center axis, and between the rotating body 1 and the head 3 of the fixed body 4,
Filled with metal fluid lubricant. As the metal fluid lubricant, for example, a gallium alloy is used. The fixed body 4 and the rotating body 1 are made of tantalum having corrosion resistance to a gallium alloy.

As shown in FIG. 2 and FIG. 3 which is an enlargement of FIG. 2, a radially inner side of a dynamic pressure groove 8 formed in the lower end surface 3b of the head 3 is drilled upward in the axial direction. A recess 10 is provided. The recess 10 is formed in an annular shape surrounding the neck 5. The lower flange 2 has a radially innermost convex portion 11. This convex part 11
Is formed so as to enter the recess 10.
The protrusion 11 is formed in an annular shape surrounding the neck 5.

The dynamic pressure bearing device for an X-ray tube having the above structure is provided inside a vacuum vessel. When the rotating body 1 rotates, the dynamic pressure groove 6 formed on the outer peripheral surface of the head 3 of the fixed body 4 generates a radial dynamic pressure in the metal fluid lubricant,
The rotating body 1 is supported in the radial direction. At the same time, the dynamic pressure grooves 7, 8 formed in the axial end surfaces 3a, 3b of the head 3 generate an axial dynamic pressure in the metal fluid lubricant, thereby supporting the rotating body 1 in the axial direction. I do.

At this time, as shown in FIG. 3, the metal fluid lubricant X flowing inward in the radial direction can be stored in the concave portion 10 by the dynamic pressure generated by the dynamic pressure groove 8.
The metal fluid lubricant Z can be prevented from leaking from the gap S between the metal fluid lubricant and the fixed body 4.

Since the concave portion 10 and the convex portion 11 having entered the concave portion 10 form a labyrinth space, the metal fluid lubricant Z can be held in the labyrinth space. Therefore, it is possible to prevent the metal fluid lubricant Z from leaking from the gap S between the rotating body 1 and the fixed body 4.

When the rotating body 1 rotates, a centrifugal force acts radially outward on the metal fluid lubricant Z in the concave portion 10, so that the metal fluid lubricant Z is directed radially outward. In addition, the metal fluid lubricant Z can be prevented from leaking from the radially inner gap S.

Therefore, according to this embodiment, leakage of the metal fluid lubricant can be effectively prevented, poor lubrication can be prevented, and the life can be extended.

In the above embodiment, the distance a between the radially outer peripheral surface of the concave portion 10 and the convex portion 11 shown in FIG.
The effect of preventing the leakage of the metal fluid lubricant can be increased by making the distance b between the metal fluid lubricant and the radially inner peripheral surface as small as possible.

Further, in the above embodiment, the cross section of the convex portion 11 is square, but it may be a triangular convex portion 41 having a tapered cross section as shown in FIG. FIG. 4 (B)
As shown in FIG. 7, the projection 42 may have a hook-shaped cross section bent radially outward.

In the above embodiment, the recess 10 is
Although the convex portion 11 is formed on the lower flange portion 2, the concave portion 10 may be formed on the lower flange portion 2 and the convex portion 11 may be formed on the head portion 3.

In the above embodiment, the cylinder 1 of the rotating body 1
Although the c and the lower flange 2 are separate bodies, the cylindrical portion 1c and the lower flange 2 may be formed integrally. Furthermore, in the above embodiment,
Although the outer cylinder member is on the rotation side and the shaft body is on the fixed side, the shaft body may be on the rotation side and the outer cylinder member may be on the fixed side. Also,
Instead of a metal lubricant made of gallium or a gallium alloy, a low-volatility vacuum grease can be used. Further, the present invention is applicable not only to the X-ray tube but also to other vacuum devices, and can be applied to a bearing device used in a normal atmosphere as long as the lubricant has a high viscosity.

[0026]

As is clear from the above, in the dynamic pressure bearing device of the present invention, the bottomed outer cylinder member has a flange portion which is opposed to the axial direction from below vertically below the head of the shaft body, An axial supporting dynamic pressure generating groove is provided on at least one of the axially facing surface of the head of the shaft body facing the flange and the axially facing surface of the flange facing the axially facing surface of the head. An axial concave portion surrounding the neck portion is formed on the axially facing surface of the flange portion of the bottomed outer cylindrical member or the axially facing surface of the head of the shaft body facing the flange portion. An axially convex portion that enters the axially concave portion is formed on an axially facing surface of the head of the shaft body that faces the flange portion or an axially facing surface of the flange portion of the bottomed outer cylindrical member. It is.

Therefore, the dynamic pressure bearing device of the present invention
Lubricant is stored in the axial recess, and leakage of the metal lubricant from the gap between the flange of the bottomed outer cylindrical member and the neck of the shaft can be prevented.

Further, since the axial concave portion and the axial convex portion entering the concave portion form a labyrinth space,
The lubricant can be held in the labyrinth space. Therefore, it is possible to prevent the lubricant from leaking from the gap between the flange of the bottomed outer cylindrical member and the neck of the shaft.

Further, when the bottomed outer cylindrical member rotates, a centrifugal force acts on the lubricant present in the axial recess toward the outside in the radial direction. It is possible to prevent the lubricant from leaking from a gap between the flange portion of the outer cylinder member and the neck portion of the radially inner shaft.

[Brief description of the drawings]

FIG. 1A is a sectional view of an embodiment of a dynamic pressure bearing device for an X-ray tube according to the present invention, and FIG. 1B is a dynamic pressure groove formed on an upper surface of a fixed body of the above embodiment. FIG. 1C is a plan view of FIG.
FIG. 4 is a plan view of a dynamic pressure groove formed on a lower surface of the fixed body of the embodiment.

FIG. 2 is a partial sectional view of a main part of the embodiment.

FIG. 3 is an enlarged sectional view of a main part of the embodiment.

FIG. 4 is a cross-sectional view showing a modified example of the convex portion formed on the lower flange portion of the rotating body of the embodiment.

FIG. 5 shows dimensions a and b between the convex portion and the concave portion in the above embodiment.
FIG.

FIG. 6 is a sectional view of a main part of a conventional dynamic pressure bearing device for an X-ray tube.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Rotating body, 1b ... Cover part, 2 ... Lower flange part, 3 ... Head, 3a
... top end surface, 3b ... bottom end surface, 4 ... fixed body, 5 ... neck, 6,
7, 8: dynamic pressure groove, 9: outer diameter portion, 10: concave portion, 11: convex portion, Z: metal fluid lubricant.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) F16C 17/10 F16C 33/74

Claims (1)

(57) [Claims] 1. A bottomed outer cylinder member, a head which rotates relative to the outer cylinder member and is disposed inside the outer cylinder member, and a neck portion which extends from the head to the outside of the outer cylinder member in an axial direction. And at least one of an inner peripheral surface of the outer cylindrical member radially opposed to the head of the shaft or an outer peripheral surface of a head of the shaft radially opposed to the outer cylindrical member. A dynamic pressure generating groove for radial direction support is formed in the bearing, and a lubricant is filled between the outer cylinder member and the shaft body; the outer cylinder member is located around the neck portion; A lower portion of the head of the shaft body having a flange portion facing in the axial direction, the flange facing the axial direction facing surface of the head portion of the shaft body facing the flange portion or the flange facing the axial direction facing surface of the head portion; An axial supporting dynamic pressure generating groove is formed on at least one of the axially opposing surfaces of the outer cylindrical member; An axial concave portion surrounding the neck portion is formed on the facing surface or the axial facing surface of the head of the shaft facing the flange portion, and the axial facing surface of the head portion of the shaft facing the flange portion. Alternatively, a dynamic pressure bearing device, wherein an axial convex portion that enters the axial concave portion is formed on an axially opposed surface of the flange portion of the outer cylindrical member.