JPS5911773B2 - Static pressure gas bearing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a hydrostatic gas bearing with improved bearing rigidity.

A conventionally commonly used hydrostatic gas bearing, for example a journal bearing, has a plurality of ten bearing nozzles that eject compressed gas onto a bearing surface that faces a rotating shaft as a supported body with a small gap. It is composed of individual parts.

The shaft is supported by the pressure distribution of the gas flowing through this gap, and bearing rigidity is given by creating a difference between the pressure on the load side and the pressure on the anti-load side by varying the gap between the bearing and the shaft. . In addition, the case of thrust bearings is shown in Figure 1.
To explain, the supported body 2 receives the thrust load of the shaft 1.
A flat bearing surface 5 of the thrust bearing 4 is provided opposite to the flat supported surface 3 of the thrust bearing 4, and compressed gas T is ejected from a plurality of bearing nozzles 6, 6 opened in this bearing surface 5 to fill the gap I.
The shaft 1 is supported by 20 through which the gas flows. Also, if the size of the gap I changes due to external force,
The pressure of the gas 7 changes, creating a force that counteracts this external force and providing rigidity. The above-mentioned rigidity will be explained using a thrust bearing as an example. When the supported body 2 and the thrust bearing 4 are in balance, an external force △f acts on the supported body 2, and the supported body 2 is displaced by Δ.

Due to this displacement, the gap 9 changes, and a force Δf in the opposite direction to the external force Δf acts on the supported body 2 to maintain balance. If this is shown in a professional diagram, it will look like Figure 2. Here F
is a function that shows the relationship between △f and △re, and G is a function that shows the relationship between △re and △f
This is a function that shows the relationship with 0. Therefore, the stiffness is △f1+F
G... (1) △Less F 35.

The rigidity of gas bearings is roughly expressed by formula (1), and although they generally have excellent characteristics of high precision and low friction, they have the disadvantage of low rigidity, and it is desired to improve this. There is.

The present invention has been made in view of the above-mentioned circumstances, and includes a bearing nozzle that supports the shaft on the bearing surface of a hydrostatic gas bearing, vacuum chambers that are located symmetrically with respect to the shaft, and vacuum chambers that support the shaft. This is a hydrostatic gas bearing with improved rigidity by adjusting the force by changing the amount of gas flowing out from the bearing nozzle.

The details of the present invention will be explained below with reference to an embodiment shown in FIGS. 3 to 5. In this embodiment, the present invention is applied to a journal static pressure gas bearing.

The main body 11 is constructed by providing a square block-like member 12 with a bearing hole 13 through which a shaft 1 as a supported body is inserted. The inner surface of this bearing hole 13 forms a bearing surface 14 . This bearing surface 14 has a bearing nozzle 1 on one end surface 16 side.
8, 19, 20, 21 are open, and the other end surface 23
Bearing nozzles 25, 26, 27, 28 are open on the sides. Since the shaft 1 extends in the horizontal direction, the bearing nozzles 18, 19, 20, and 21 are arranged at 90° vertically and horizontally within the same vertical plane.
The openings are spaced apart from each other at equal intervals, and the other end is opened at one end surface 16, respectively. Compressed gas 7 is introduced through openings 18a, 19a, 20a, and 21a in these end faces 16, and is ejected from bearing nozzles 18, 19, 20, and 21 to support shaft 1. Also, the bearing nozzle 2 on the other end face 17 side
The openings 25a, 26a, 27a, and
Compressed gas 7 is introduced from 28a to bearing nozzles 25, 26.
, 27, 28 to support the shaft 1. A bearing surface 31 on one side and a bearing surface 32 on the other side facing each other via the shaft 1 are provided with vacuum chambers 34 and 35 each consisting of a recess opened in each surface. These communicate with pressure reducing bodies 36 and 37 attached to the main body 11. The pressure reducing bodies 36 and 37 are connected to a gas flow path 40 having narrow portions 38 and 39,
41, compressed gas 42 is passed through a so-called Rabaul-shaped nozzle to obtain reduced pressure. The vacuum chambers 34, 35 communicate with these gas channels 40, 41 and are always kept at a much lower pressure than the gas pressure in the bearing gap. It goes without saying that the vacuum chambers 34 and 35 may be connected to a vacuum device such as a general vacuum pump. Between the vacuum chamber 34 and the bearing nozzles 18, 25 are provided arcuate guide grooves 44, 45 which are open to the bearing surface 31 on one side, and these guide grooves 44, 45 have one end. It extends along the bearing surface 31 and communicates with the vacuum chamber 35 of the other bearing surface 32 . And between the bearing nozzle 18 and one end surface 16 and between the bearing nozzle 25 and the other end surface 17 are arc-shaped guide grooves 46 similar to the above-mentioned guide grooves 44 and 45.
, 47 are provided, which communicate with the guide grooves 44, 45, respectively, within the main body 11. These guide grooves 44, 45, 46, 47 allow the bearing nozzles 18, 2
Compressed gas (air) 7 ejected from 5 is sucked and enters the vacuum chamber 35, and is further discharged to the atmosphere via a decompression body 37. On the other hand, guide grooves 50 and 51 are provided on the other side of the bearing surface 32 between the vacuum chamber 35 and the bearing nozzles 20 and 27, and also between the one end surface 16 and the bearing nozzle 20 and the other end surface. Guide grooves 52 and 53 are also provided between the bearing nozzle 17 and the bearing nozzle 27, respectively. These guide grooves 50,
51, 52, 53 are in communication with the vacuum chamber 34 and are connected to the guide groove 44.
, 45, 46, and 47, and have similar functions, so the explanation thereof will be omitted. Next, the operation will be explained.

Gas (compressed air) 7 is passed through openings 18a and 19a in one end surface 16.
, 20a, 21a and openings 25a, 26 in the other end surface 17.
a, 27a, 28a, and bearing nozzles 18, 1
9, 20, 21 and bearing nozzles 25, 26, 27, 2
Squirt from 8. When compressed gas (air) 42 is supplied to the gas flow paths 40, 41 of the pressure reducing bodies 36, 37, the compressed gas (air) 42 expands adiabatically in the pinched portions 38, 39 and the pressure drops, so that the vacuum chambers 34, 35 are vacuumed. The state is depressurized. As a result, the gas 7 ejected from the bearing nozzles 18 and 25 is sucked into the guide grooves 46 and 44 and the guide grooves 47 and 45, enters the vacuum chamber 35, passes through the decompression body 37, and is discharged to the atmosphere. The compressed gas (air) 7 ejected from the bearing nozzles 20 and 27 similarly enters the vacuum chamber 34 and is discharged to the atmosphere via the pressure reducing body 36. Similarly, the compressed gas (air) 7 ejected from the bearing nozzles 19, 21, 26, 28 enters the vacuum chambers 34, 35 as appropriate and is discharged to the atmosphere. In this state, the pressing force of gas from the bearing nozzles 18, . In this state,
When an external force Δf in the direction of the arrow 55 acts on the shaft 1 from above to below, the upper gap f! 1 is large, and the lower gap G2 is small.

As a result, the flow rate of gas (air) 7 from the bearing nozzles 18, 25 increases, and therefore the amount of gas (air) 7 flowing into the vacuum chamber 35 increases, the degree of pressure reduction decreases, and the suction force ( direction of arrow 55) decreases. On the other hand, the flow rate of gas (air) 7 from the lower bearing nozzles 20, 27 decreases,
The amount of gas 7 flowing into the vacuum chamber 34 decreases, the degree of pressure reduction increases, and the suction force (in the opposite direction to arrow 55) in this area increases. The above changes are shown in a block diagram as shown in FIG. That is, the change in the external force mentioned above is △f1, the amount of change in the gap 9 due to this is △H, the function expressing the relationship between △f and △h is F, and △h is used for the bearing nozzles 18, 20, 25.
, 27 is ΔFl, the function representing the relationship between Δh and ΔF is G, the suction force generated in the vacuum chamber 34 by Δh is ΔF2, and similarly the suction force generated in the vacuum chamber 35 is Δ Assuming that the vacuum formation functions representing the relationship between F3, △h and △F2 and the relationship between △h and △F3 are respectively Vl, , as shown in Figure 5, △Fl, △F2, and △F3 are all It acts in the opposite direction to △f and its stiffness Δfll+F(j
(1±V1 and V2 is one =
...(2).

ΔHF, that is, equation (1) representing the above-mentioned stiffness and (2)
If you compare FG (V1 + V2) with the formula, it is clear that the stiffness is greater.

Note that within the bearing, a change in clearance (△h) occurs in response to a change in external force (△f), and an internal pressure change corresponding to the change in external force is generated to generate a force that is balanced by △f.

This is a type of feedback control, and a system as shown in FIG. 2 is established. Next, the present invention will be explained.

In FIG. 5, if we take the system 1 and 2, we get the above-mentioned uniform bearing. By the way, in the present invention, the upper and lower parts of the bearing have 34 and 35 parts.
There are vacuum chambers such as these to discharge the fluid flowing in from the bearings, and since they are vacuum chambers, they naturally generate suction forces F2 and f3. Since the suction force is proportional to the degree of vacuum, it is inversely proportional to the flow rate flowing from the bearing. Therefore, △f→△h→
In addition to the single-transport bearing action of △f1, a new action of "HTZ?7r" is generated. Therefore, the control system shown in Fig. 5 is obtained.To summarize this, the equation (2) becomes .

As described in detail above, the hydrostatic gas bearing device of the present invention is provided with a bearing nozzle, and a vacuum chamber is provided between the bearing surface on one side and the bearing surface on the other side via the supported body. The gas from the bearing nozzle is sucked into the vacuum chamber on the other side,
Since the configuration is such that the gas from the bearing nozzle on the other side is sucked into the vacuum chamber on one side, an increase or decrease in the flow rate of gas from the bearing nozzle on one side will cause a decrease in the suction force in the vacuum chamber on the other side. As a result, the rigidity due to the repulsive force generated by the vacuum chamber is added to the conventional rigidity, and the rigidity is significantly greater than the conventional rigidity, making it possible to provide a high-precision bearing that is stable against external forces.

Although this embodiment has been described with respect to a journal bearing, it goes without saying that the present invention is also applicable to a thrust bearing.

It also applies to general support parts.

[Brief explanation of the drawing]

FIG. 1 is a partially sectional front view showing the main parts of the conventional example, FIG. 2 is a block diagram explaining the rigidity of the conventional example, FIG. 3 is a sectional front view of an embodiment of the present invention, and FIG. FIG. 3 is a sectional view taken along the line IV-1V in the direction of the arrow, and FIG. 5 is a block diagram for explaining the rigidity of an embodiment of the present invention. 1, 2: Supported body, 7: Gas, 14: Bearing surface, 16: - side end face, 17: Other end face, 18, 19, 20, 21
, 25, 26, 27, 28: Bearing nozzle, 31: Bearing surface on the - side, 32: Bearing surface on the other side, 34: Vacuum chamber on the - side, 35: Vacuum chamber on the other side, 44, 45, 46, 47:
- guide grooves, 50, 51, 52, 53: guide grooves on the other side.

Claims (1)

[Scope of Claims] 1. A plurality of bearing nozzles that are provided on a bearing surface and eject gas to support a supported object, and a plurality of bearing nozzles that are opened in the bearing surface on one side facing each other with the supported object in between, and a vacuum one vacuum chamber that communicates with the vacuum source, the other vacuum chamber that opens in the bearing surface on the other side facing through the shaft and communicates with the vacuum source, and the vacuum chamber that is provided in the bearing surface of the one side and that one guide groove that communicates with the other vacuum chamber and guides the gas ejected from the bearing nozzle on the one bearing surface to the other vacuum chamber; A static pressure gas bearing device comprising: a second guide groove that communicates with a vacuum chamber and guides the gas ejected from a bearing nozzle on the other bearing surface to the one vacuum chamber. 2 One guide groove is provided between the outermost bearing nozzle provided on the bearing surface on one side and the end face, and between the innermost bearing nozzle and one vacuum chamber, and the guide groove on the other side is provided between the outermost bearing nozzle and the end face. is provided between the outermost bearing nozzle provided on the other side bearing surface and the end face, and between the innermost bearing nozzle and the other vacuum chamber. The static pressure gas bearing device according to item 1.