JPS62209221A - Static pressure bearing - Google Patents

Abstract

PURPOSE:To aim at enhancing the durability and rotational accuracy of a bearing, by arranging a guide and injection means opened to the support surface of a rotary shaft, and a discharge passage in a bearing body while a partition wall is disposed between the means and the discharge passage. CONSTITUTION:Air fed from a gas supply pump 4 is fed to a thrust bearing 6 and a radial bearing 7 through a pipe 5. Fluid lubrication films are formed in thrust and radial gaps 8, 9, and air supporting a thrust bearing 2 and a rotary shaft 1 is led to fluid discharge parts 10a, 10b, and is then discharged to the atmosphere outside the chamber from the discharge parts 10a, 10b through a pipe line 11. Further, a partition wall 12 restrains the atmospheric air from entering into a fluid discharge part 10c while the pipe resistance by partition walls 12b, 12c restrains the flow rate of air flowing into the chamber.

Description

Detailed Description of the Invention [Field of the Invention] The present invention relates to a semiconductor exposure apparatus such as an electron beam exposure apparatus, an X-ray exposure apparatus, an ion beam exposure apparatus, a vapor deposition apparatus, a C
This invention relates to a hydrostatic bearing used in a rotating mechanism of a device operating in vacuum, such as a VD device.

[Background of the Invention] Conventionally, ball bearings used in rotating parts in vacuum have generally been cleaned and coated with vacuum grease, or the balls have been subjected to treatments such as gold or silver ion blating. However, not only do they have problems with durability, but they also have 1 μm for contact support.
It was extremely difficult to obtain a rotation accuracy of less than m.

[Object of the Invention] An object of the present invention is to provide a hydrostatic bearing that can obtain high durability and rotational accuracy in a vacuum.

This object, according to the invention, comprises a bearing body, a housing surrounding the bearing body, an air supply pump installed outside the housing, and a suction pump, said bearing body being connected to said air supply pump. , a guide and ejecting means for guiding and ejecting fluid to the support surface of the rotary shaft, and a discharge connected to the suction pump and open to the support surface for suctioning and discharging the fluid flowing out onto the support surface of the rotary shaft. This is achieved by means of a hydrostatic bearing comprising channels and partitions which are arranged alternately with discharge channels and which extend close to said support surface.

In particular, in a preferred embodiment of the present invention, an annular bearing body is arranged in an annular space formed by a rotating shaft and thrust receivers at both ends thereof, and a porous radial bearing is provided on a radial surface of the annular bearing body surrounding the rotating shaft. A porous thrust bearing is provided inwardly on the thrust surface of the annular bearing body facing the thrust receiver, and a partition wall is provided on the thrust surface outwardly, so that the radial bearing and An air supply pump is connected to a conduit inside the bearing body that communicates with the thrust bearing, and a suction pump is connected to a conduit that opens on the surface of the bearing body between the bulkhead and the surface of the bearing body between the radial bearing and the thrust bearing. are doing.

[Embodiment] FIG. 1 is a plan view of an embodiment of the hydrostatic bearing of the present invention, and FIG. 2 is a sectional view taken along lines AB and CB in FIG. 1. 1 is a rotating shaft, 2 is a thrust receiver, and 3 is a bearing body. The hydrostatic bearing body is housed within a vacuum chamber. 4 is an air supply pump outside the chamber, and 5 is a conduit in the bearing body 3, which is open to the radial surface and thrust surface of the bearing body. 6 is a thrust bearing, 7 is a radial bearing, 8 is a thrust clearance, 9
is a radial gap, 10a-10d are fluid suction and discharge parts, 1
1 is a pipe line communicating with the suction/discharge portions 10a and 10b of the bearing body 3; 12a-12c are partition walls; 13 is a suction pump;
4.16 is a conduit communicating with the suction/discharge portions 10c and 10d of the bearing body 3, and 15 is a suction pump.

Air supplied from the air supply pump 4 passes through a conduit 5 and is supplied to the thrust bearing 6 and the radial bearing 7.

A porous material is used for the thrust bearing 6 and the radial bearing 7 because it can provide high rigidity and reduce the flow rate used. A fluid lubricant film is formed between the thrust gap 8 and the radial gap 9, and the air that supports the thrust receiver 2 and the rotating shaft 1 reaches the fluid discharge parts 10a and 10b, and from there passes through the conduit 11 to the outside of the chamber. released into the atmosphere. Therefore, the pressure distribution in the thrust gap 8 and the radial gap 9 is the same as in the atmosphere, and the rigidity is also the same as in the atmosphere.

The pressure in the fluid discharge part 10b is approximately equal to atmospheric pressure and 1
It is atmospheric pressure. Therefore, the fluid tries to flow out to the chamber side where the pressure is lower, but since the gap with the thrust receiver 2 is made very small by the partition wall 12a, the pipe resistance is large, and the fluid discharge part 1
The flow rate flowing into 0C is extremely small. Further, a suction pump 15 outside the chamber passes the fluid through the pipe line 14 to the fluid discharge part 1.
Evacuate to 0c to reduce the pressure in this area. Furthermore, the pipe resistance due to the partition wall 12b and the suction pump 1 outside the chamber
3, the flow rate flowing into the chamber can be made very small by exhausting the fluid from the fluid discharge section 10d through the pipe line 16 and the resistance of the pipe line by the partition wall 12c.

The ultimate pressure within the chamber is determined by the pumping speed of the pump suctioning the chamber and the balance of the flow out of the hydrostatic bearing into the chamber. For example, the gap between the thrust receiver 2 and the partition wall 12 is set to a little less than 10 um, and the suction pump 13.1
If an oil rotary pump with a pumping speed of about several hundred JZ/min is used for the pump 5, the pressure in the fluid discharge section 10d can be made to be about IXIQ-')-1. The outer diameter is 2QOmm, and the pump suctioning the chamber is pumped at a pumping speed of 1000℃/se.
If it is a turbo molecular pump of c, the pressure inside the chamber is about 1
It can be maintained at 0-' l-le.

By further narrowing the gap between the thrust receiver 2 and the partition wall 12, further increasing the pumping speed of the pump that sucks the chamber, and increasing the number of fluid discharge parts and partition walls, the pressure at the final fluid discharge part is reduced. The pressure can be around 10-61-bar.

In this embodiment, a static pressure bearing that is a combination of a thrust bearing and a radial bearing is shown, but a similar configuration can be made with a single thrust bearing or a single radial bearing.

[Effects of the Invention] The present invention makes it possible to improve the durability and rotation accuracy of a hydrostatic bearing in a vacuum atmosphere.

[Brief explanation of drawings]

Fig. 1 is a plan view showing one embodiment of the present invention, and Fig. 2 is a plan view showing an embodiment of the present invention.
It is a sectional view along AB, BC of a figure. 1: Rotating shaft 2 Ni thrust receiver 3: Bearing body 4: Air supply pump 5: Pipe line 6: Thrust bearing 7: Radial bearing 8 Ni thrust gap 9 Ni radial gap 10a - 10d: Fluid discharge part 11: Pipe line 12a - 12c: Partition wall 13: Suction pump 14: Pipe line 15: Suction pump.

Claims (1)

[Claims] 1. A bearing body, a housing surrounding the bearing body, an air supply pump installed outside the housing, and a suction pump, wherein the bearing body is connected to the air supply pump. a guide and ejecting means connected to and for guiding and ejecting fluid to the support surface of the rotary shaft; and a guide and ejecting means connected to the suction pump and open to the support surface for suctioning and discharging the fluid flowing out to the support surface of the rotary shaft. A hydrostatic bearing characterized in that it comprises a discharge channel and a partition wall which is arranged alternately with the discharge channel and which extends close to said support surface. 2. The static pump according to claim 1, wherein the guide jetting means includes an air supply path connected to the air supply pump, and a porous thrust bearing connected to the air supply path. Pressure bearing. 3. The static pump according to claim 1, wherein the guide jetting means comprises an air supply path connected to the air supply pump, and a porous radial bearing connected to the air supply path. Pressure bearing. 4. According to claim 1, the guide jetting means comprises an air supply path connected to the air supply pump, and a porous thrust bearing and a radial bearing connected to the air supply path. Hydrostatic bearings as described.