JP2557733Y2 - Hydrostatic gas bearing - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a hydrostatic gas bearing in which a pressurized gas is supplied to a gap between a housing and a rotary shaft to rotatably support the rotary shaft in the housing. A large moment rigidity is obtained on the bearing surface in the direction.

[0002]

2. Description of the Related Art As a conventional static pressure gas bearing in which a rotary shaft is rotatably supported in a non-contact manner on a housing by a pressurized gas supplied to a space between a housing and a rotary shaft, there is, for example, Japanese Patent Publication No. Sho-46. There is one described in JP-A-12682. This conventional hydrostatic gas bearing is formed by the inner peripheral surface of the housing and the outer peripheral surface of the rotating shaft by inserting the rotating shaft into the housing with a gap and fixing thrust plates to both ends of the rotating shaft. Radial gap, and a thrust gap formed by the end face of the housing and the thrust plate, the radial gap,
The rotary shaft is divided into two parts by a circumferentially continuous convex part on the outer surface in the central part in the axial direction of the rotating shaft, and a diaphragm is formed radially outside the gap in the thrust direction.

The housing has a supply passage for supplying pressurized air to an axial end of a radial gap divided into two parts, and an opening at a position opposed to the convex part formed on the rotating shaft. An exhaust passage is perforated. Therefore, the pressurized air supplied from the supply passage is supplied to the radial gap and the thrust gap, and the throttle action of the convex portion formed on the rotating shaft and the step formed at the radial end of the thrust gap are provided. The diaphragm provides the bearing rigidity.

When the rotating shaft is displaced relative to the housing in the radial direction or the thrust direction, the pressure in the radial gap or the thrust gap increases in a portion where the rotating shaft approaches the housing and decreases in a portion away from the rotating shaft. Therefore, a restoring force is generated by the differential pressure, and rigidity in the radial and thrust directions is secured. Further, even in the case where a relative displacement occurs in the direction in which the rotation axis is inclined with respect to the housing, the description in the above-mentioned publication describes that sufficient rigidity in the moment direction is secured because a sufficient restoring force is obtained. ing.

[0005]

However, in the above-described conventional hydrostatic gas bearing, when the rotating shaft is inclined with respect to the housing, the pressure at the portion where the housing and the rotating shaft approach each other surely increases. Although a restoring force is generated, a large amount of pressurized air escapes from the part in the same thrust direction gap where the housing and the rotating shaft separate from each other because the thrust direction gap is formed over the entire thrust plate surface. ,
Therefore, there is a disadvantage that the pressure in the approaching portion does not rise so much and the actually obtained restoring force is small.

For this reason, since it is necessary to receive a moment force also by the radial gap, the radial direction has a double row bearing structure so as to increase the rigidity in the radial direction. It gets bigger. The present invention focuses on the unsolved problems of the conventional technology, and a static pressure in which a large moment rigidity is obtained by a thrust direction bearing surface while securing the thrust direction rigidity. It is intended to provide a gas bearing.

[0007]

In order to achieve the above object, according to the present invention, a pressurized gas is supplied to a gap between a housing and a rotating shaft to rotatably support the rotating shaft on the housing. In the hydrostatic gas bearing, a surface on the housing side that forms a first thrust direction gap that expands and contracts in accordance with a relative displacement in the thrust direction between the housing and the rotating shaft, and in accordance with the relative displacement in the thrust direction. The space where the pressurized gas is supplied to the housing-side surface forming a second thrust-direction gap that expands and contracts in a direction opposite to the first thrust-direction gap. The three spaces formed in the circumferential direction so that the circumferential positions coincide with each other, the three spaces formed in the surface on one housing side, and the front spaces formed on the surface on the other housing side. The three spaces are paired with each other at the same circumferential position, and the paired spaces are pressurized in a large amount in a space having a large pressure according to a pressure difference between the spaces and the space. Via a control throttle valve that supplies gas
Connected to a pressurized gas supply.

[0008]

According to the present invention, since the space for supplying the pressurized gas is formed at three circumferential positions on the respective housing-side surfaces of the first and second thrust gaps, Due to the inclination of the rotation axis, even if the space where the pressure rises and the space where the pressure drops are mixed among the three spaces formed on the same housing-side surface, they will not affect each other. I will not give each other.

When the pressure in the space rises, a large amount of pressurized gas is supplied to the space by the action of the control throttle valve to increase the pressure, while being supplied to the space paired with the gas. The pressurized gas decreases and the pressure in the space decreases, but such a paired space is formed at the same position in the circumferential direction, so the difference between the paired space and the space The pressure generates a large restoring force against the inclination of the rotating shaft.

Further, since three spaces for supporting the load in the thrust direction are formed in each of the first and second gaps in the thrust direction, since one plane is specified by three points, two spaces or three spaces are provided. Stable support can be performed as compared with a case where a space is formed in four or more places to support a thrust load.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 6 show an embodiment of the present invention, in which the present invention is applied to a hydrostatic gas bearing 1 that supports both the radial and thrust directions of a rotating shaft by pressurized air. Things.

First, the structure will be described. As shown in FIG. 1, a hydrostatic gas bearing 1 includes a cylindrical housing 2 supported horizontally and a rotating shaft 3 rotatably supported by the housing 2. The rotating shaft 3 includes a shaft portion 4 inserted into the housing 2 with a small gap,
Disc-shaped thrust plates 5 and 6 are coaxially fixed to both ends of the shaft portion 4.

The inner peripheral surface of the housing 2 is indicated by AA in FIG.
As shown in FIG. 2 which is a line cross-sectional view, the shaft portion 4 is sandwiched from the vertical direction and the horizontal direction at equal intervals in the circumferential direction so as to sandwich the shaft portion 4, and is recessed in a flat “field” shape as shown in FIG. Radial grooves 10A, 10B, 10C and 10D are formed at four locations, and these radial grooves 10A to 10D
The supply passage 11A through the housing 2
To 11D are open.

The supply passages 11A, 11B communicate with the radial grooves 10A, 10B formed so as to sandwich the rotary shaft 4 from the horizontal direction.
B is connected to the output ports 12a, 12a of the control throttle valve 12A, and the supply passages 11C, 11D communicating with the radial grooves 10C, 10D formed so as to sandwich the rotary shaft 4 from above and below are provided at the control throttle valve 12B. Output port 12
a, 12a.

Here, in this embodiment, a first thrust gap 13A is formed by one end surface 2A of the housing 2 and the thrust plate 5, and a second thrust plate 13 is formed by the other end surface 2B of the housing 2 and the thrust plate 6. Are formed in the thrust direction gap 13B, and the end faces 2A and 2B
FIG. 4 shows the end faces 2A and 2B viewed from the front.
As shown in the figure, a thrust direction as a space in which a plurality of (three in this embodiment) circumferential grooves 15a to 15c extending in the circumferential direction are communicated with the radial grooves 16 extending in the radial direction at three positions in the circumferential direction. Grooves 17A, 17B, 17C and 18A, 18
B, 18C are formed. However, the thrust direction grooves 17A, 17B, and 17C formed on the end face 2A and the thrust direction grooves 18A, 18B, and 18C formed on the end face 2B are located around the rotation axis 3 between them. It is formed so that the direction positions match.

Each of the thrust direction grooves 17A to 17A
C, the supply passage 19A through the inside of the housing 2 at the intersection of the circumferential groove 15b and the radial groove 16 of 18A to 18C.
To 19C, 20A to 20C, and supply passages 19A, 20A communicating with thrust grooves 17A, 18A formed at the same circumferential position are connected to output ports 12a, 12a of the control throttle valve 12C, The supply passages 19B and 20B communicating with the thrust grooves 17B and 18B formed at the same circumferential position are connected to the output ports 12a and 12a of the control throttle valve 12D, and the thrust grooves 17C formed at the same circumferential position. , 18C communicate with the output port 12 of the control throttle valve 12E.
a, 12a.

Further, circumferential grooves 2C and 2D are formed in the inner peripheral edges of the end faces 2A and 2B so as to cut out the edges, and the circumferential grooves 2C and 2D are formed. Are connected to exhaust passages 2E and 2F formed in the housing 2 as shown in FIG. On the other hand, each of the control throttle valves 12A to 12E has two air chambers 12d, 12d formed by dividing the inside of a hollow housing 12b by a leaf spring 12c, as shown in FIG.
12e, and the air chambers 12d and 12e
It is connected to the discharge side of a pressurized air supply source (not shown) via input ports 12f and 12g.

In each of the air chambers 12d and 12e,
Protrusions 12h and 12i are formed so as to face the leaf spring 12c, and output ports 12a and 12a are opened on the surfaces of the protrusions 12h and 12i on the leaf spring 12c side. next,
The operation of this embodiment will be described. That is, the pressurized air supplied from the pressurized air supply source is supplied from the input ports 12f, 12g to the respective air chambers 12d, 12e, and from the gaps 12j, 12k between the leaf spring 12c and the protrusions 12h, 12i. It reaches the input ports 12a, 12a, from which radial grooves 10A to 10D and thrust grooves 17A to 17C, 1
8A to 18C, but if there is no difference between the pressures in the air chambers 12d and 12e, no deformation occurs in the leaf spring 12c. Therefore, each radial groove and thrust connected to the same control throttle valve 12A to 12E. The same amount of pressurized air is supplied to the direction grooves. In addition, each radial groove 10A ~
10D, thrust direction grooves 17A-17C, 18A-18
C is supplied to the housing 2 and the rotating shaft 3
The air is discharged directly to the outside from the gap between the holes and to the outside through the circumferential grooves 2C and 2D and the exhaust passages 2E and 2F.

Therefore, the rotating shaft 3 is supported in a non-contact manner by the pressurized air in the two pairs of radial grooves 10A to 10D in the radial direction, and has three pairs of thrust grooves 17A to 17C, 18A to 18C in the thrust direction. Non-contact is supported by the pressurized air inside. Here, assuming that a relative displacement occurs between the housing 2 and the rotating shaft 3 in a direction in which the rotating shaft 3 descends with respect to the housing 2 (downward in the Y-axis direction shown in FIGS. 1 and 2). Since the gap between the inner peripheral surface and the outer peripheral surface of the shaft portion 4 increases on the side of the radial groove 10C and decreases on the side of the radial groove 10D, the pressure in the radial groove 10D increases within the radial groove 10C. Higher than the pressure.

Then, the radial groove 10C communicates with the air chamber 12d in the control throttle valve 12B, and the radial groove 10C
Assuming that D communicates with the air chamber 12e in the control throttle valve 12B, the differential pressure between the gaps 12j and 12k changes in the direction in which the gap 12k becomes larger, and the leaf spring 12c
h, the gap 12j is reduced,
The gap 12k expands.

As a result, a larger amount of pressurized air is supplied to the radial groove 10D side than to the radial groove 10C,
Since the pressure in the radial groove 10D further increases and the pressure in the radial groove 10C further decreases, a force in the direction of lifting the shaft portion 4 is generated, whereby the shaft portion 4 moves toward the neutral position. Be energized. In the radial direction other than the Y-axis direction, a force that constantly urges the shaft portion 4 toward the neutral position is applied to the shaft portion 4 by the same pressure change in the radial grooves 10A to 10D. That is, the rotary shaft 3 is formed by the radial grooves 10A to 10D.
In the radial direction.

Next, assuming that the rotation shaft 3 is displaced relative to the housing 2 in the Z-axis direction in FIG. 1 between the housing 2 and the rotation shaft 3, the first thrust gap 13
A decreases and the second thrust gap 13B increases. Then, the thrust direction groove 1 formed on the end face 2A side
Since the pressure in the thrust grooves 17A to 17C decreases and the pressure in the thrust grooves 18A to 18C formed on the end face 2B side decreases, the internal pressure of the thrust grooves 17A to 17C is reduced by the action of the control throttle valves 12C to 12E. Since it further rises and the pressure in the thrust direction grooves 18A to 18C further falls,
A force for urging the rotating shaft 3 to the left in FIG. 1 is generated.

When the rotary shaft 3 is displaced relative to the housing 2 in the direction opposite to the Z-axis direction in FIG. 1, the rotary shaft 3 is urged rightward in FIG. A force is generated. In other words, the thrust direction supporting stiffness of the rotating shaft 3 is obtained by the thrust direction grooves 17A to 17C and 18A to 18C. Next, a case where a relative displacement occurs between the housing 2 and the rotating shaft 3 in a direction in which the rotating shaft 3 is inclined with respect to the housing 2 will be described.

For example, in FIG. 1, assuming that a relative displacement occurs in which the rotating shaft 3 is inclined in the direction in which the thrust plate 6 moves downward, the first thrust gap 13A is Z
It contracts in a portion above the axis and enlarges in a portion below the Z axis. Conversely, the second thrust direction gap 13B
Expands in a portion above the Z axis and contracts in a portion below the Z axis.

Then, by the action of the control throttle valves 12C to 12E, the pressure on the thrust direction groove 17A side further increases between the thrust direction grooves 17A and 18A, and between the thrust direction grooves 17B and 18B, the thrust direction groove 18B side. Of the thrust direction grooves 17C and 18
Between C, the pressure on the thrust direction groove 18C side further increases.

At this time, the same thrust direction gaps 13A, 13A
3B, the thrust direction groove 17 in which the pressure is further increased
A, 18B, and 18C and thrust grooves 18A, 17B, and 17C in which the pressure is further reduced are mixed. In the configuration of the present embodiment, each of the thrust grooves 17A to 17C.
7C, 18A to 18C are independent of each other, and the paired ones are connected to one control throttle valve 12C to 12E, so that the groove where the pressure rises and the groove where the pressure descends interact. There is no.

As a result, in a portion above the Z axis, a force is generated in a direction to bring the thrust plate 6 closer to the end face 2B, and Z
In a portion below the axis, a force is generated in a direction in which the thrust plate 5 approaches the end face 2A. Similarly, the thrust direction grooves 17A to 17C, 1 are also provided for other relative displacements in the inclination direction.
8A to 18C generate a force in a direction against the inclination.

To summarize the above operation, as shown in FIG. 6, the rigidity in the X-axis direction and the Y-axis direction is ensured by the radial grooves 10A to 10D, and the θ _X direction and θ _Y
The moment rigidity in the direction is the thrust direction grooves 17A-17.
C, is ensured by 18A to 18C, with respect to the theta _Z direction moment, radial grooves 10A to 10D, the thrust grooves 17A-17C, the 18A to 18C, smooth rotation is ensured.

That is, according to the structure of this embodiment, the rigidity against the moments in the θ _X direction and the θ _Y direction can be obtained by the thrust grooves 17A to 17C and 18A to 18C. The diameter can be easily increased by increasing the diameter of the end surfaces 2A, 2B and the thrust plates 5, 6, so that the radial grooves 10A to 10D can be increased.
Then, it is not necessary to receive the moments in the θ _X direction and the θ _Y direction.

Therefore, the radial grooves 10A to 10D
Is sufficient if sufficient rigidity in the radial direction can be ensured. For example, in order to increase the rigidity of the radial grooves 10A to 10D with respect to the moments in the θ _X direction and the θ _Y direction, the radial bearing surface has a double-row structure. Since there is no need, the axial dimension can be reduced, which is very suitable for making the hydrostatic gas bearing 1 thin.

The hydrostatic gas bearing 1 of this embodiment has high rigidity particularly in the thrust direction, and is suitable for use with the rotating shaft 3 standing upright. Further, in this embodiment, the thrust direction grooves 17A to 17A to secure the rigidity in the thrust direction are provided.
C, 18A to 18C are formed in three pairs, because one plane is specified at three points and stable support can be performed.

That is, even when the thrust direction grooves are formed in two pairs or four pairs, if they are independent from each other as in this embodiment, it is certain that the thrust grooves have high rigidity against the moments in the θ _X direction and the θ _Y direction. Is obtained, but in this case, one plane cannot be determined by the thrust direction grooves on the same thrust direction gaps 13A and 13B side.

[0033]

[Effects of the Invention] As described above, according to the present invention,
Since the rigidity in the thrust direction is secured by three pairs of thrust grooves connected to the pressurized fluid supply source via the control throttle valve, a large thrust rigidity is obtained, and the thrust direction grooves provide the Since rigidity can be secured, the thickness of the static pressure gas bearing can be reduced.
As a result, the effect that stable support can be obtained is obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a plan view of a radial groove.

FIG. 4 is a side view of the housing.

FIG. 5 is a sectional view of a control throttle valve.

FIG. 6 is a diagram illustrating support rigidity in each direction.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Static pressure gas bearing 2 Housing 2A, 2B End surface 3 Rotation shaft 4 Shaft part 5, 6 Thrust plate 10A-10D Radial groove 12A-12E Control throttle valve 13A 1st thrust gap 13B 2nd thrust gap 17A- 17C Thrust direction groove 18A-18C Thrust direction groove

Claims (1)

(57) [Scope of request for utility model registration] 1. A static pressure gas bearing for supplying a pressurized gas to a gap between a housing and a rotating shaft to rotatably support the rotating shaft in the housing, wherein a static pressure gas bearing is provided between the housing and the rotating shaft. A surface on the housing side that forms a first thrust direction gap that expands and contracts in accordance with the relative displacement in the thrust direction, and a first thrust direction gap that expands and contracts in a direction opposite to the first thrust direction gap in accordance with the relative displacement in the thrust direction. The space where the pressurized gas is supplied to each of the surfaces on the housing side forming the thrust direction gap 2 is provided at three places in the circumferential direction such that the circumferential positions of the surfaces on the housing side coincide with each other. While forming, the three spaces formed on one housing-side surface and the three spaces formed on the other housing-side surface are paired with each other when their circumferential positions match, Then, the paired spaces are controlled via a control throttle valve that supplies a large amount of the pressurized gas to a space having a larger pressure according to a differential pressure between the spaces and the space.
A hydrostatic gas bearing connected to a pressurized gas supply source.