JPH07103236A - Static pressure bearing device - Google Patents

Abstract

PURPOSE:To provide a static pressure bearing device, by which gas leakage from a porous member can be easily prevented, in a static pressure bearing device using a porous member. CONSTITUTION:An outside surface of the porous member 4 except a bearing surface 1a, from which gas is jetted toward a gas supply surface 5 receiving gas supply from a housing 3 and a rotary shaft 4, is covered by an elastic member 2. A porous member 1 is installed in the housing 3 via the elastic member 2 so that the gas supply surface 5 faces a gas chamber 7 of the housing 3. In this way, the surfaces except the gas supply surface 5 of the porous member 1 and the bearing surface 1a are tightly covered by the elastic member 2, so that gas leakage from these parts can be prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydrostatic bearing device for supporting a rotary shaft by a gas ejected from a porous member.

[0002]

2. Description of the Related Art Conventionally, as a static pressure bearing device of this type,
There is one shown in FIG. In this hydrostatic bearing device B, a gas supply surface 5 is formed on a part of the outer periphery of a cylindrical porous member 1, and the gas supply surface 5 and the outer surface of the porous member 1 other than the inner peripheral bearing surface 1a are formed. Clogging is performed by plating or resin impregnation to prevent gas from leaking from this portion. Then, the porous member 1 is covered with a metal member 8, the porous member 1 is attached to the fixed member (housing) 3 through the metal member 8, and the rotating shaft 4 is supported by the bearing surface 1a of the porous member 1. .

In the hydrostatic bearing device B, compressed gas is supplied to the gas supply surface 5 of the porous member 1 through the gas passage 6 of the fixed member 3 and the gas chamber 7 of the metal member 8. Then, the compressed gas passes through the minute pores in the porous member 1 and is ejected from the bearing surface 1a at the inner circumference, and the bearing surface 1a and the rotating shaft 4
A compressed gas layer is created in the clearance G between
Support.

[0004]

In the above-mentioned conventional hydrostatic bearing device B, it is necessary to cover the surfaces of the porous member 1 other than the bearing surface 1a and the gas supply surface 5 by plating, resin impregnation or the like. This process requires a lot of man-hours, and there is a problem that the sealing effect is not reliable.

When a plurality of conventional hydrostatic bearing devices B are used, the inner peripheral cylindrical surface of the housing 3 is inclined with respect to the center line L due to an error in cutting as shown in FIG. Bearing surface 1 of hydrostatic bearing device B1, B2
The center line C of a may not coincide with the center line L of the rotary shaft 4. At this time, the clearance G between the bearing surface 1a of the hydrostatic bearing device B1, B2 and the periphery of the rotary shaft 4 is not uniform around the rotary shaft 4. When the compressed gas is ejected in this state, the gas pressure in the clearance G becomes non-uniform,
The center line L of the rotary shaft 4 turns while tilting with respect to the center line C of the bearing surface 1a of the hydrostatic bearing device B1, B2, and the whirling motion of the rotary shaft 4 occurs.

Therefore, an object of the present invention is to prevent leakage of gas from the outer surface of the porous member other than the gas supply surface and the bearing surface in the hydrostatic bearing device using the porous member, and
An object of the present invention is to provide a hydrostatic bearing device capable of aligning the bearing surface when the rotating shaft is assembled.

[0007]

In order to achieve the above object, in the hydrostatic bearing device of the present invention, a fixing member is a porous member having a bearing surface on the inner circumference and a gas supply surface on a portion other than the inner circumference. And a static pressure bearing for supporting the rotary shaft inserted into the porous member by ejecting the gas supplied to the gas supply surface from the bearing surface. In the device, the outer surface of the porous member other than the gas supply surface and the bearing surface is covered, and at least a part is interposed between the porous member and the fixing member to fix the porous member. It is characterized in that an elastic member attached to the member is provided.

[0008]

Since the outer surface of the porous member of the hydrostatic bearing device having the above structure is covered with the elastic member except for the gas supply surface for receiving gas supply and the bearing surface for ejecting gas, the gas supply surface and the bearing surface are covered. No gas leaks from the outer surface of the porous member except for.

Further, when the rotary shaft is inserted into the hydrostatic bearing device, the center line of the bearing surface does not coincide with the center line of the rotary shaft, and the clearance between the bearing surface and the rotary shaft is not uniform in the circumferential direction. , After inserting the rotary shaft into the hydrostatic bearing device and moving the rotary shaft to one side in the radial direction, the porous member is strongly pressed outward in the radial direction in the place where the clearance is narrow, and the elastic member is also porous. It is strongly pressed by the member. Therefore, the elastic member on the side of the narrow clearance is compressed and deformed more than the elastic member on the side of the wide clearance to widen the clearance. Therefore, according to the present invention, the non-uniform clearance around the rotation axis is made uniform. That is, according to the hydrostatic bearing device of the present invention, when the rotary shaft is inserted, the elastic member is compressed and deformed by moving the rotary shaft in one of the radial directions, and the center line of the bearing surface is the center line of the rotary shaft. Aligned to match.

As described above, according to the present invention, by covering the porous member with the elastic member, gas leakage from the porous member can be prevented, and when the clearance around the rotating shaft becomes uneven. Then, by pressing the rotating shaft against the porous member, the elastic member is compressed, the bearing surface is aligned with the rotating shaft, and the clearance between the rotating shaft and the bearing surface is uniform around the rotating shaft. To be done. Therefore, the rotating shaft is always supported stably.

[0011]

The present invention will be described in detail below with reference to the embodiments shown in the drawings.

FIG. 1 shows a hydrostatic bearing device S according to an embodiment of the present invention.
FIG. The hydrostatic bearing device S of this embodiment includes a cylindrical porous member 1 made of sintered metal, a housing 3 as a fixed member on which the porous member 1 is arranged on the inner circumference,
An elastic member 2 made of resin such as rubber or elastic plastic is provided between the porous member 1 and the housing 3 to fix the porous member 1 to the inner peripheral surface of the housing 3. A rotary shaft 4 is inserted in the bearing surface 1a on the inner circumference of the porous member 1. On the other hand, an annular gas chamber 7 is formed between the housing 3 and the porous member 1. The outer peripheral surface of the porous member 1 facing the gas chamber 7 serves as the gas supply surface 5. The housing 3 is provided with a gas passage 6 which extends in the radial direction and communicates with the gas chamber 7. The elastic member 2 closely covers and covers the outer surfaces of the porous member 1 other than the gas supply surface 5 and the bearing surface 1a, the compressed gas is supplied only from the gas supply surface 5, and the compressed gas is blown out only from the bearing surface 1a. I am trying to do it.

As shown in FIG. 4, the elastic member 2 is made of resin or rubber in a substantially cylindrical shape whose axial cross section is substantially U-shaped. Recessed portion 2b to which the porous member 1 is fixed
Is formed so as to be slightly smaller than the outer dimension of the porous member 1, supports the porous member 1 so as not to shift in the axial direction, and adheres to the outer surface of the porous member 1 to prevent leakage of compressed gas. Make sure to prevent. Further, a plurality of grooves 2a are provided in the circumferential direction on the bottom surface of the recess 2b, and these are provided in the gas chamber 7
To form.

In addition to the above embodiment, the elastic member 2 may be formed by attaching a ring-shaped member made of resin or rubber having an axial cross section of a substantially L shape to both ends of the porous member 1 in the axial direction. .

In the hydrostatic bearing device S, since the outer surface of the porous member 1 other than the gas supply surface 5 and the bearing surface 1a is tightly covered with the elastic member 2, the porous member 1 is covered with the elastic member 2. No gas leaks from the outer surface of the member 1. Therefore, the flow rate of the compressed gas in the hydrostatic bearing device S can be minimized.

FIG. 2 shows a hydrostatic bearing device S3 having the same structure as in FIG.
Two S4 and S4 are arranged in the axial direction and attached to the inner peripheral surface of the housing 3. The center line C of the bearing surface 1a and the center line L of the rotary shaft 4 of the hydrostatic bearing device S3 and the hydrostatic bearing device S4 are the same when the housing 3 is attached.
There is a case where they do not always match due to an error in machining the inner peripheral cylindrical surface (however, FIG. 2 is a diagram showing a state after the both center lines C and L are corrected so as to match). Therefore, the circumferential distribution of the clearance G between the bearing surface 1a of the porous member 1 of the hydrostatic bearing devices S3, S4 and the rotary shaft 4 is not uniform. Looking at the upper clearance of the rotary shaft 4 in FIG. 2, the left clearance G4 is narrow and the right clearance G3 is wide before correction. However, in the present embodiment, the rotating shaft 4 is moved to the upper side in the radial direction and the rotating shaft 4 is pressed against the porous member 1, so that the porous member 1 has a narrow clearance G and a wide clearance G3. Compared with, it is strongly pressed outward in the radial direction.
Therefore, the elastic member 2 on the side of the portion G4 where the clearance G is narrow is pressed radially outward by the porous member 1 and the elastic member 2 in the portion near the portion G4 where the clearance G is narrow is compressed. On the other hand, the degree of contraction of the elastic member 2 in the portion close to the portion G3 where the clearance G is wide is small, and the clearance becomes uniform. Thus, FIG.
As shown in, the center line C of the bearing surface 1a of the hydrostatic bearing device S3, S4 coincides with the center line L of the rotary shaft 4. In this way, it is possible to make the clearance G, which was not uniform at the time of assembly, uniform.

Therefore, according to the present embodiment, the rotating shaft 4 and the bearing surface can be formed by utilizing the rotating shaft even if the machining accuracy of the hydrostatic bearing device or the housing 3 for mounting the hydrostatic bearing device is not so high. The clearance between them can be made uniform, and the rotating shaft can be always supported stably.

As shown in FIG. 3, when the outer peripheral surface 40 of the elastic member 2 is curved so as to be convex toward the center in the axial direction, the elastic member 2 and the porous member 1 are integrated. Since it can be easily swung in a plane including the axis of the rotary shaft 4 and can be easily deformed in the radial direction of the rotary shaft 4, any axial misalignment of the rotary shaft 4 can be dealt with, In addition, the amount of alignment can be increased.

In the above embodiment, sintered metal is used as the porous member, but ceramic may be used.

[0020]

As is apparent from the above, according to the present invention, the entire outer surface of the porous member having the gas supply surface and the bearing surface other than the gas supply surface and the bearing surface is covered with the elastic member. The gas leakage from the porous member can be prevented, and the flow rate of the compressed gas can be minimized.

Further, according to the present invention, the center line of the rotary shaft and the center line of the bearing surface of the hydrostatic bearing device do not coincide with each other during assembly due to processing errors of the components of the hydrostatic bearing device.
Even if the clearance between the rotating shaft and the bearing surface is not uniform, the rotating member is moved in the radial direction and pressed against the bearing surface, so that the porous member is not moved radially outward at a narrow clearance. Since the elastic member is compressed toward one side to widen the narrow clearance, the clearance between the rotary shaft and the bearing surface can be adjusted uniformly. Therefore, according to the present invention, it is possible to align the centers of the rotary shaft and the bearing surface with a simple work at the time of assembling, without increasing the working accuracy of the components of the hydrostatic bearing device.

[Brief description of drawings]

FIG. 1 is a sectional view of an embodiment of a hydrostatic bearing device of the present invention.

FIG. 2 is a cross-sectional view of an example in which two hydrostatic bearing devices of the above embodiment of the present invention are used.

FIG. 3 is a sectional view of another embodiment of the present invention.

FIG. 4 is an external perspective view of the elastic member according to the embodiment of the present invention.

FIG. 5 is a cross-sectional view of a conventional hydrostatic bearing device.

FIG. 6 is a sectional view of an example in which two conventional hydrostatic bearing devices are used.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Porous member, 1a ... Bearing surface, 2 ... Elastic member, 3 ... Housing, 4 ... Rotating shaft, 5 ... Gas supply surface, 6 ... Gas passage, 7 ... Gas chamber, G ... Clearance.

Claims (1)

[Claims] 1. A porous member having a bearing surface on the inner circumference and a gas supply surface on a portion other than the inner circumference is attached to a fixed member such that the gas supply surface faces the fixed member, and the gas supply is performed. In a hydrostatic bearing device for supporting a rotating shaft inserted in the porous member by ejecting gas supplied to the surface from the bearing surface, the outer surface of the porous member other than the gas supply surface and the bearing surface is A hydrostatic bearing device comprising: an elastic member that covers and at least partially interposes between the porous member and the fixing member to attach the porous member to the fixing member.